Fix crash flushing cache on unmount events (#895)

* Too bad we can't require explicit build deps...

* More deps

.allstar/binary_artifacts.yaml

@@ -0,0 +1,18 @@
+# Ignore reason: These crafted binaries are used in tests
+ignorePaths:
+- Source/common/testdata/bad_pagezero
+- Source/common/testdata/missing_pagezero
+- Source/common/testdata/missing_pagezero
+- Source/common/testdata/missing_pagezero
+- Source/common/testdata/32bitplist
+- Source/common/testdata/BundleExample.app/Contents/MacOS/BundleExample
+- Source/common/testdata/DirectoryBundle/Contents/MacOS/DirectoryBundle
+- Source/common/testdata/DirectoryBundle/Contents/Resources/BundleExample.app/Contents/MacOS/BundleExample
+- Source/santad/testdata/binaryrules/badbinary
+- Source/santad/testdata/binaryrules/goodbinary
+- Source/santad/testdata/binaryrules/badcert
+- Source/santad/testdata/binaryrules/banned_teamid_allowed_binary
+- Source/santad/testdata/binaryrules/banned_teamid
+- Source/santad/testdata/binaryrules/goodcert
+- Source/santad/testdata/binaryrules/noop
+- Source/santad/testdata/binaryrules/rules.db

.bazelrc

@@ -3,3 +3,14 @@ build --apple_generate_dsym --define=apple.propagate_embedded_extra_outputs=yes
 build --copt=-Werror
 build --copt=-Wall
 build --copt=-Wno-error=deprecated-declarations
+build --per_file_copt=.*\.mm\$@-std=c++17
+build --cxxopt=-std=c++17
+
+build:asan --strip=never
+build:asan --copt="-Wno-macro-redefined"
+build:asan --copt="-D_FORTIFY_SOURCE=0"
+build:asan --copt="-O1"
+build:asan --copt="-fno-omit-frame-pointer"
+build:asan --copt="-fsanitize=address"
+build:asan --copt="-DADDRESS_SANITIZER"
+build:asan --linkopt="-fsanitize=address"

.bazelversion

@@ -1 +1 @@
-5.0.0
+5.3.0

.github/workflows/check-markdown.yml

@@ -11,4 +11,4 @@ jobs:
     steps:
     - uses: actions/checkout@master
     - uses: gaurav-nelson/github-action-markdown-link-check@v1
-    - run: "! git grep -EIn $'[ \t]+$'"
+    - run: "! git grep -EIn $'[ \t]+$' -- ':(exclude)*.patch'"

.github/workflows/ci.yml

@@ -20,7 +20,6 @@ jobs:
       - name: Run linters
         run: ./Testing/lint.sh
 
-
   build_userspace:
     strategy:
       fail-fast: false
@@ -55,10 +54,3 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           path-to-lcov: ./bazel-out/_coverage/_coverage_report.dat
           flag-name: Unit
-
-  benchmark:
-    runs-on: macos-11
-    steps:
-      - uses: actions/checkout@v2
-      - name: Run All Tests
-        run: ./Testing/benchmark.sh

BUILD

@@ -198,10 +198,3 @@ test_suite(
         "//Source/santasyncservice:unit_tests",
     ],
 )
-
-test_suite(
-    name = "benchmarks",
-    tests = [
-        "//Source/santad:SNTApplicationBenchmark",
-    ],
-)

README.md

@@ -1,7 +1,7 @@
-# Santa [![CI](https://github.com/google/santa/actions/workflows/ci.yml/badge.svg)](https://github.com/google/santa/actions/workflows/ci.yml) [![Coverage Status](https://coveralls.io/repos/github/google/santa/badge.svg?branch=main)](https://coveralls.io/github/google/santa?branch=main)
+# Santa [![CI](https://github.com/google/santa/actions/workflows/ci.yml/badge.svg)](https://github.com/google/santa/actions/workflows/ci.yml)
 
 <p align="center">
-    <img src="https://raw.githubusercontent.com/google/santa/main/Source/santa/Resources/Images.xcassets/AppIcon.appiconset/santa-hat-icon-128.png" alt="Santa Icon" />
+    <img src="https://raw.githubusercontent.com/google/santa/main/Source/gui/Resources/Images.xcassets/AppIcon.appiconset/santa-hat-icon-128.png" alt="Santa Icon" />
 </p>
 
 Santa is a binary authorization system for macOS. It consists of a system

Source/common/BUILD

@@ -83,12 +83,6 @@ objc_library(
     ],
 )
 
-objc_library(
-    name = "SNTAllowlistInfo",
-    srcs = ["SNTAllowlistInfo.m"],
-    hdrs = ["SNTAllowlistInfo.h"],
-)
-
 objc_library(
     name = "SNTCommonEnums",
     hdrs = ["SNTCommonEnums.h"],
@@ -106,6 +100,23 @@ objc_library(
     ],
 )
 
+objc_library(
+    name = "SNTKVOManager",
+    srcs = ["SNTKVOManager.mm"],
+    hdrs = ["SNTKVOManager.h"],
+    deps = [
+        ":SNTLogging",
+    ],
+)
+
+santa_unit_test(
+    name = "SNTKVOManagerTest",
+    srcs = ["SNTKVOManagerTest.mm"],
+    deps = [
+        ":SNTKVOManager",
+    ],
+)
+
 objc_library(
     name = "SNTDropRootPrivs",
     srcs = ["SNTDropRootPrivs.m"],
@@ -117,6 +128,7 @@ objc_library(
     srcs = ["SNTFileInfo.m"],
     hdrs = ["SNTFileInfo.h"],
     deps = [
+        ":SNTLogging",
         "@FMDB",
         "@MOLCodesignChecker",
     ],
@@ -298,13 +310,40 @@ santa_unit_test(
     deps = [":SNTMetricSet"],
 )
 
+santa_unit_test(
+    name = "SNTCachedDecisionTest",
+    srcs = ["SNTCachedDecisionTest.mm"],
+    deps = [
+        "//Source/common:SNTCachedDecision",
+        "//Source/common:TestUtils",
+        "@OCMock",
+    ],
+)
+
 test_suite(
     name = "unit_tests",
     tests = [
+        ":SNTCachedDecisionTest",
         ":SNTFileInfoTest",
+        ":SNTKVOManagerTest",
         ":SNTMetricSetTest",
         ":SNTPrefixTreeTest",
+        ":SNTRuleTest",
         ":SantaCacheTest",
     ],
     visibility = ["//:santa_package_group"],
 )
+
+objc_library(
+    name = "TestUtils",
+    testonly = 1,
+    srcs = ["TestUtils.mm"],
+    hdrs = ["TestUtils.h"],
+    sdk_dylibs = [
+        "bsm",
+    ],
+    deps = [
+        "@OCMock",
+        "@com_google_googletest//:gtest",
+    ],
+)

Source/common/SNTAllowlistInfo.m

@@ -1,32 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import "Source/common/SNTAllowlistInfo.h"
-
-@implementation SNTAllowlistInfo
-
-- (instancetype)initWithPid:(pid_t)pid
-                 pidversion:(int)pidver
-                 targetPath:(NSString *)targetPath
-                     sha256:(NSString *)hash {
-  self = [super init];
-  if (self) {
-    _pid = pid;
-    _pidversion = pidver;
-    _targetPath = targetPath;
-    _sha256 = hash;
-  }
-  return self;
-}
-@end

Source/common/SNTCachedDecision.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,10 +12,11 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
+#import <EndpointSecurity/EndpointSecurity.h>
 #import <Foundation/Foundation.h>
 
-#import "Source/common/SNTCommonEnums.h"
 #import "Source/common/SNTCommon.h"
+#import "Source/common/SNTCommonEnums.h"
 
 @class MOLCertificate;
 
@@ -24,6 +25,8 @@
 ///
 @interface SNTCachedDecision : NSObject
 
+- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile;
+
 @property santa_vnode_id_t vnodeId;
 @property SNTEventState decision;
 @property NSString *decisionExtra;

Source/common/SNTCachedDecision.m

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -15,4 +15,14 @@
 #import "Source/common/SNTCachedDecision.h"
 
 @implementation SNTCachedDecision
+
+- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile {
+  self = [super init];
+  if (self) {
+    _vnodeId.fsid = (uint64_t)esFile->stat.st_dev;
+    _vnodeId.fileid = esFile->stat.st_ino;
+  }
+  return self;
+}
+
 @end

Source/common/SNTCachedDecisionTest.mm

@@ -0,0 +1,36 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <XCTest/XCTest.h>
+
+#import "Source/common/SNTCachedDecision.h"
+#include "Source/common/TestUtils.h"
+
+@interface SNTCachedDecisionTest : XCTestCase
+@end
+
+@implementation SNTCachedDecisionTest
+
+- (void)testSNTCachedDecisionInit {
+  // Ensure the vnodeId field is properly set from the es_file_t
+  struct stat sb = MakeStat(1234, 5678);
+  es_file_t file = MakeESFile("foo", sb);
+
+  SNTCachedDecision *cd = [[SNTCachedDecision alloc] initWithEndpointSecurityFile:&file];
+
+  XCTAssertEqual(sb.st_ino, cd.vnodeId.fileid);
+  XCTAssertEqual(sb.st_dev, cd.vnodeId.fsid);
+}
+
+@end

Source/common/SNTCommon.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -27,41 +27,22 @@
 #define unlikely(x) __builtin_expect(!!(x), 0)
 
 typedef enum {
-  ACTION_UNSET = 0,
+  ACTION_UNSET,
 
   // REQUESTS
-  ACTION_REQUEST_SHUTDOWN = 10,
-  ACTION_REQUEST_BINARY = 11,
+  // If an operation is awaiting a cache decision from a similar operation
+  // currently being processed, it will poll about every 5 ms for an answer.
+  ACTION_REQUEST_BINARY,
 
   // RESPONSES
-  ACTION_RESPOND_ALLOW = 20,
-  ACTION_RESPOND_DENY = 21,
-  ACTION_RESPOND_TOOLONG = 22,
-  ACTION_RESPOND_ACK = 23,
-  ACTION_RESPOND_ALLOW_COMPILER = 24,
-  // The following response is stored only in the kernel decision cache.
-  // It is removed by SNTCompilerController
-  ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE = 25,
-
-  // NOTIFY
-  ACTION_NOTIFY_EXEC = 30,
-  ACTION_NOTIFY_WRITE = 31,
-  ACTION_NOTIFY_RENAME = 32,
-  ACTION_NOTIFY_LINK = 33,
-  ACTION_NOTIFY_EXCHANGE = 34,
-  ACTION_NOTIFY_DELETE = 35,
-  ACTION_NOTIFY_WHITELIST = 36,
-  ACTION_NOTIFY_FORK = 37,
-  ACTION_NOTIFY_EXIT = 38,
-
-  // ERROR
-  ACTION_ERROR = 99,
+  ACTION_RESPOND_ALLOW,
+  ACTION_RESPOND_DENY,
+  ACTION_RESPOND_ALLOW_COMPILER,
 } santa_action_t;
 
 #define RESPONSE_VALID(x)                                   \
   (x == ACTION_RESPOND_ALLOW || x == ACTION_RESPOND_DENY || \
-   x == ACTION_RESPOND_ALLOW_COMPILER ||                    \
-   x == ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE)
+   x == ACTION_RESPOND_ALLOW_COMPILER)
 
 // Struct to manage vnode IDs
 typedef struct santa_vnode_id_t {
@@ -75,28 +56,4 @@ typedef struct santa_vnode_id_t {
 #endif
 } santa_vnode_id_t;
 
-typedef struct {
-  santa_action_t action;
-  santa_vnode_id_t vnode_id;
-  uid_t uid;
-  gid_t gid;
-  pid_t pid;
-  int pidversion;
-  pid_t ppid;
-  char path[MAXPATHLEN];
-  char newpath[MAXPATHLEN];
-  char ttypath[MAXPATHLEN];
-  // For file events, this is the process name.
-  // For exec requests, this is the parent process name.
-  // While process names can technically be 4*MAXPATHLEN, that never
-  // actually happens, so only take MAXPATHLEN and throw away any excess.
-  char pname[MAXPATHLEN];
-
-  // This points to a copy of the original ES message.
-  void *es_message;
-
-  // This points to an NSArray of the process arguments.
-  void *args_array;
-} santa_message_t;
-
 #endif  // SANTA__COMMON__COMMON_H

Source/common/SNTCommonEnums.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -57,6 +57,7 @@ typedef NS_ENUM(NSInteger, SNTEventState) {
   SNTEventStateBlockCertificate = 1 << 18,
   SNTEventStateBlockScope = 1 << 19,
   SNTEventStateBlockTeamID = 1 << 20,
+  SNTEventStateBlockLongPath = 1 << 21,
 
   // Bits 24-31 store allow decision types
   SNTEventStateAllowUnknown = 1 << 24,
@@ -120,5 +121,4 @@ typedef NS_ENUM(NSInteger, SNTMetricFormatType) {
 static const char *kSantaDPath =
   "/Applications/Santa.app/Contents/Library/SystemExtensions/"
   "com.google.santa.daemon.systemextension/Contents/MacOS/com.google.santa.daemon";
-static const char *kSantaCtlPath = "/Applications/Santa.app/Contents/MacOS/santactl";
 static const char *kSantaAppPath = "/Applications/Santa.app";

Source/common/SNTConfigurator.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -65,7 +65,8 @@
 ///      <key>rule_type</key>
 ///      <string>BINARY</string>  (one of BINARY, CERTIFICATE or TEAMID)
 ///      <key>policy</key>
-///      <string>BLOCKLIST</string>  (one of ALLOWLIST, ALLOWLIST_COMPILER, BLOCKLIST, SILENT_BLOCKLIST)
+///      <string>BLOCKLIST</string>  (one of ALLOWLIST, ALLOWLIST_COMPILER, BLOCKLIST,
+///                                   SILENT_BLOCKLIST)
 ///    </dict>
 ///  </array>
 ///
@@ -244,15 +245,6 @@
 ///
 @property(readonly, nonatomic) BOOL enableMachineIDDecoration;
 
-///
-///  Use an internal cache for decisions instead of relying on the caching
-///  mechanism built-in to the EndpointSecurity framework. This may increase
-///  performance, particularly when Santa is run alongside other system
-///  extensions.
-///  Has no effect if the system extension is not being used. Defaults to NO.
-///
-@property(readonly, nonatomic) BOOL enableSysxCache;
-
 #pragma mark - GUI Settings
 
 ///

Source/common/SNTConfigurator.m

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2014-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@
 
 /// Holds the last processed hash of the static rules list.
 @property(atomic) NSDictionary *cachedStaticRules;
+
 @end
 
 @implementation SNTConfigurator
@@ -94,8 +95,6 @@ static NSString *const kMailDirectoryEventMaxFlushTimeSec = @"MailDirectoryEvent
 
 static NSString *const kEnableMachineIDDecoration = @"EnableMachineIDDecoration";
 
-static NSString *const kEnableSysxCache = @"EnableSysxCache";
-
 static NSString *const kEnableForkAndExitLogging = @"EnableForkAndExitLogging";
 static NSString *const kIgnoreOtherEndpointSecurityClients = @"IgnoreOtherEndpointSecurityClients";
 static NSString *const kEnableDebugLogging = @"EnableDebugLogging";
@@ -206,7 +205,6 @@ static NSString *const kSyncCleanRequired = @"SyncCleanRequired";
       kMailDirectorySizeThresholdMB : number,
       kMailDirectoryEventMaxFlushTimeSec : number,
       kEnableMachineIDDecoration : number,
-      kEnableSysxCache : number,
       kEnableForkAndExitLogging : number,
       kIgnoreOtherEndpointSecurityClients : number,
       kEnableDebugLogging : number,
@@ -425,10 +423,6 @@ static NSString *const kSyncCleanRequired = @"SyncCleanRequired";
   return [self syncAndConfigStateSet];
 }
 
-+ (NSSet *)keyPathsForValuesAffectingEnableSysxCache {
-  return [self configStateSet];
-}
-
 + (NSSet *)keyPathsForValuesAffectingEnableForkAndExitLogging {
   return [self configStateSet];
 }
@@ -793,11 +787,6 @@ static NSString *const kSyncCleanRequired = @"SyncCleanRequired";
   return number ? [number boolValue] : NO;
 }
 
-- (BOOL)enableSysxCache {
-  NSNumber *number = self.configState[kEnableSysxCache];
-  return number ? [number boolValue] : YES;
-}
-
 - (BOOL)enableCleanSyncEventUpload {
   NSNumber *number = self.configState[kSyncEnableCleanSyncEventUpload];
   return number ? [number boolValue] : NO;

Source/common/SNTFileInfo.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,6 +12,7 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
+#import <EndpointSecurity/EndpointSecurity.h>
 #import <Foundation/Foundation.h>
 
 @class MOLCodesignChecker;
@@ -32,6 +33,14 @@
 ///
 - (instancetype)initWithPath:(NSString *)path error:(NSError **)error;
 
+///
+///  Convenience initializer.
+///
+///  @param esFile Pointer to an es_file_t provided by the EndpointSecurity framework.
+///      Assumes that the path is a resolved path.
+///
+- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile error:(NSError **)error;
+
 ///
 ///  Convenience initializer.
 ///

Source/common/SNTFileInfo.m

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -25,6 +25,8 @@
 #include <sys/stat.h>
 #include <sys/xattr.h>
 
+#import "Source/common/SNTLogging.h"
+
 // Simple class to hold the data of a mach_header and the offset within the file
 // in which that header was found.
 @interface MachHeaderWithOffset : NSObject
@@ -48,6 +50,7 @@
 @property NSFileHandle *fileHandle;
 @property NSUInteger fileSize;
 @property NSString *fileOwnerHomeDir;
+@property NSString *sha256Storage;
 
 // Cached properties
 @property NSBundle *bundleRef;
@@ -63,6 +66,26 @@
 extern NSString *const NSURLQuarantinePropertiesKey WEAK_IMPORT_ATTRIBUTE;
 
 - (instancetype)initWithResolvedPath:(NSString *)path error:(NSError **)error {
+  struct stat fileStat;
+  if (path.length) {
+    lstat(path.UTF8String, &fileStat);
+  }
+  return [self initWithResolvedPath:path stat:&fileStat error:error];
+}
+
+- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile error:(NSError **)error {
+  return [self initWithResolvedPath:@(esFile->path.data) stat:&esFile->stat error:error];
+}
+
+- (instancetype)initWithResolvedPath:(NSString *)path
+                                stat:(const struct stat *)fileStat
+                               error:(NSError **)error {
+  if (!fileStat) {
+    // This is a programming error. Bail.
+    LOGE(@"NULL stat buffer unsupported");
+    exit(EXIT_FAILURE);
+  }
+
   self = [super init];
   if (self) {
     _path = path;
@@ -76,9 +99,7 @@ extern NSString *const NSURLQuarantinePropertiesKey WEAK_IMPORT_ATTRIBUTE;
       return nil;
     }
 
-    struct stat fileStat;
-    lstat(_path.UTF8String, &fileStat);
-    if (!((S_IFMT & fileStat.st_mode) == S_IFREG)) {
+    if (!((S_IFMT & fileStat->st_mode) == S_IFREG)) {
       if (error) {
         NSString *errStr = [NSString stringWithFormat:@"Non regular file: %s", strerror(errno)];
         *error = [NSError errorWithDomain:@"com.google.santa.fileinfo"
@@ -88,12 +109,12 @@ extern NSString *const NSURLQuarantinePropertiesKey WEAK_IMPORT_ATTRIBUTE;
       return nil;
     }
 
-    _fileSize = fileStat.st_size;
+    _fileSize = fileStat->st_size;
 
     if (_fileSize == 0) return nil;
 
-    if (fileStat.st_uid != 0) {
-      struct passwd *pwd = getpwuid(fileStat.st_uid);
+    if (fileStat->st_uid != 0) {
+      struct passwd *pwd = getpwuid(fileStat->st_uid);
       if (pwd) {
         _fileOwnerHomeDir = @(pwd->pw_dir);
       }
@@ -214,9 +235,13 @@ extern NSString *const NSURLQuarantinePropertiesKey WEAK_IMPORT_ATTRIBUTE;
 }
 
 - (NSString *)SHA256 {
-  NSString *sha256;
-  [self hashSHA1:NULL SHA256:&sha256];
-  return sha256;
+  // Memoize the value
+  if (!self.sha256Storage) {
+    NSString *sha256;
+    [self hashSHA1:NULL SHA256:&sha256];
+    self.sha256Storage = sha256;
+  }
+  return self.sha256Storage;
 }
 
 #pragma mark File Type Info

Source/common/SNTKVOManager.h

@@ -0,0 +1,34 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+// The callback type when KVO notifications are received for observed key paths.
+// The first parameter is the previous value, the second paramter is the new value.
+typedef void (^KVOCallback)(id oldValue, id newValue);
+
+@interface SNTKVOManager : NSObject
+
+// Add an observer for the selector on the given object. When a KVO notification
+// is received, the callback is called. If the notification contains objects that
+// are not of the expectedType, nil is passed as the argument to the callback.
+// The observer is removed when the returned instance is deallocated.
+- (instancetype)initWithObject:(id)object
+                      selector:(SEL)selector
+                          type:(Class)expectedType
+                      callback:(KVOCallback)callback;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+@end

Source/common/SNTKVOManager.mm

@@ -0,0 +1,72 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#import "Source/common/SNTKVOManager.h"
+
+#import "Source/common/SNTLogging.h"
+
+@interface SNTKVOManager ()
+@property KVOCallback callback;
+@property Class expectedType;
+@property NSString *keyPath;
+@property id object;
+@end
+
+@implementation SNTKVOManager
+
+- (instancetype)initWithObject:(id)object
+                      selector:(SEL)selector
+                          type:(Class)expectedType
+                      callback:(KVOCallback)callback {
+  self = [super self];
+  if (self) {
+    NSString *selectorName = NSStringFromSelector(selector);
+    if (![object respondsToSelector:selector]) {
+      LOGE(@"Attempt to add observer for an unknown selector (%@) for object (%@)", selectorName,
+           [object class]);
+      return nil;
+    }
+
+    _object = object;
+    _keyPath = selectorName;
+    _expectedType = expectedType;
+    _callback = callback;
+
+    [object addObserver:self
+             forKeyPath:selectorName
+                options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld)
+                context:NULL];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [self.object removeObserver:self forKeyPath:self.keyPath context:NULL];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath
+                      ofObject:(id)object
+                        change:(NSDictionary<NSString *, id> *)change
+                       context:(void *)context {
+  id oldValue = [change[NSKeyValueChangeOldKey] isKindOfClass:self.expectedType]
+                  ? change[NSKeyValueChangeOldKey]
+                  : nil;
+  id newValue = [change[NSKeyValueChangeNewKey] isKindOfClass:self.expectedType]
+                  ? change[NSKeyValueChangeNewKey]
+                  : nil;
+
+  self.callback(oldValue, newValue);
+}
+
+@end

Source/common/SNTKVOManagerTest.mm

@@ -0,0 +1,129 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#import <XCTest/XCTest.h>
+
+#import "Source/common/SNTKVOManager.h"
+
+@interface Foo : NSObject
+@property NSNumber *propNumber;
+@property NSArray *propArray;
+@property id propId;
+@end
+
+@implementation Foo
+@end
+
+@interface SNTKVOManagerTest : XCTestCase
+@end
+
+@implementation SNTKVOManagerTest
+
+- (void)testInvalidSelector {
+  Foo *foo = [[Foo alloc] init];
+
+  SNTKVOManager *kvo = [[SNTKVOManager alloc] initWithObject:foo
+                                                    selector:NSSelectorFromString(@"doesNotExist")
+                                                        type:[NSNumber class]
+                                                    callback:^(id, id){
+                                                    }];
+
+  XCTAssertNil(kvo);
+}
+
+- (void)testNormalOperation {
+  Foo *foo = [[Foo alloc] init];
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+
+  int origVal = 123;
+  int update1 = 456;
+  int update2 = 789;
+
+  foo.propNumber = @(origVal);
+
+  // Store the values from the callback to test against expected values
+  __block int oldVal;
+  __block int newVal;
+
+  SNTKVOManager *kvo =
+    [[SNTKVOManager alloc] initWithObject:foo
+                                 selector:@selector(propNumber)
+                                     type:[NSNumber class]
+                                 callback:^(NSNumber *oldValue, NSNumber *newValue) {
+                                   oldVal = [oldValue intValue];
+                                   newVal = [newValue intValue];
+                                   dispatch_semaphore_signal(sema);
+                                 }];
+  XCTAssertNotNil(kvo);
+
+  // Ensure an update to the observed property triggers the callback
+  foo.propNumber = @(update1);
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+                 "Failed waiting for first observable update");
+  XCTAssertEqual(oldVal, origVal);
+  XCTAssertEqual(newVal, update1);
+
+  // One more time why not
+  foo.propNumber = @(update2);
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+                 "Failed waiting for second observable update");
+  XCTAssertEqual(oldVal, update1);
+  XCTAssertEqual(newVal, update2);
+}
+
+- (void)testUnexpectedTypes {
+  Foo *foo = [[Foo alloc] init];
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+
+  NSString *origVal = @"any_val";
+  NSString *update = @"new_val";
+  foo.propId = origVal;
+
+  __block id oldVal;
+  __block id newVal;
+
+  SNTKVOManager *kvo = [[SNTKVOManager alloc] initWithObject:foo
+                                                    selector:@selector(propId)
+                                                        type:[NSString class]
+                                                    callback:^(id oldValue, id newValue) {
+                                                      oldVal = oldValue;
+                                                      newVal = newValue;
+                                                      dispatch_semaphore_signal(sema);
+                                                    }];
+  XCTAssertNotNil(kvo);
+
+  // Update to an unexpected type (here, NSNumber instead of NSString)
+  foo.propId = @(123);
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+                 "Failed waiting for first observable update");
+  XCTAssertEqualObjects(oldVal, origVal);
+  XCTAssertNil(newVal);
+
+  // Update again with an expected type, ensure oldVal is now nil
+  foo.propId = update;
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+                 "Failed waiting for first observable update");
+  XCTAssertNil(oldVal);
+  XCTAssertEqualObjects(newVal, update);
+}
+
+@end

Source/common/SNTRule.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -51,18 +51,18 @@
 ///  Designated initializer.
 ///
 - (instancetype)initWithIdentifier:(NSString *)identifier
-                         state:(SNTRuleState)state
-                          type:(SNTRuleType)type
-                     customMsg:(NSString *)customMsg
-                     timestamp:(NSUInteger)timestamp;
+                             state:(SNTRuleState)state
+                              type:(SNTRuleType)type
+                         customMsg:(NSString *)customMsg
+                         timestamp:(NSUInteger)timestamp;
 
 ///
 ///  Initialize with a default timestamp: current time if rule state is transitive, 0 otherwise.
 ///
 - (instancetype)initWithIdentifier:(NSString *)identifier
-                         state:(SNTRuleState)state
-                          type:(SNTRuleType)type
-                     customMsg:(NSString *)customMsg;
+                             state:(SNTRuleState)state
+                              type:(SNTRuleType)type
+                         customMsg:(NSString *)customMsg;
 
 ///
 ///  Initialize with a dictionary received from a sync server.

Source/common/SNTStoredEvent.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -95,7 +95,6 @@
 ///
 @property NSArray *signingChain;
 
-
 ///
 /// If the executed file was signed, this is the Team ID if present in the signature information.
 ///

Source/common/SNTStrengthify.h

@@ -1,4 +1,4 @@
-/// Copyright 2016 Google Inc. All rights reserved.
+/// Copyright 2016-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,10 +12,14 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#define STRONGIFY(var)                                 \
-  _Pragma("clang diagnostic push")                     \
-      _Pragma("clang diagnostic ignored \"-Wshadow\"") \
-          __strong __typeof(var) var = (Weak_##var);   \
+// clang-format off
+
+#define STRONGIFY(var)                             \
+  _Pragma("clang diagnostic push")                 \
+  _Pragma("clang diagnostic ignored \"-Wshadow\"") \
+  __strong __typeof(var) var = (Weak_##var);   \
   _Pragma("clang diagnostic pop")
 
 #define WEAKIFY(var) __weak __typeof(var) Weak_##var = (var);
+
+// clang-format on

Source/common/SNTSystemInfo.m

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -18,8 +18,11 @@
 @implementation SNTSystemInfo
 
 + (NSString *)serialNumber {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   io_service_t platformExpert =
     IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
+#pragma clang diagnostic pop
   if (!platformExpert) return nil;
 
   NSString *serial = CFBridgingRelease(IORegistryEntryCreateCFProperty(
@@ -31,8 +34,11 @@
 }
 
 + (NSString *)hardwareUUID {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   io_service_t platformExpert =
     IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
+#pragma clang diagnostic pop
   if (!platformExpert) return nil;
 
   NSString *uuid = CFBridgingRelease(IORegistryEntryCreateCFProperty(

Source/common/SNTXPCUnprivilegedControlInterface.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -15,8 +15,8 @@
 #import <Foundation/Foundation.h>
 #import <MOLCertificate/MOLCertificate.h>
 
-#import "Source/common/SNTCommonEnums.h"
 #import "Source/common/SNTCommon.h"
+#import "Source/common/SNTCommonEnums.h"
 
 @class SNTRule;
 @class SNTStoredEvent;
@@ -31,7 +31,6 @@
 ///  Cache Ops
 ///
 - (void)cacheCounts:(void (^)(uint64_t rootCache, uint64_t nonRootCache))reply;
-- (void)cacheBucketCount:(void (^)(NSArray *))reply;
 - (void)checkCacheForVnodeID:(santa_vnode_id_t)vnodeID withReply:(void (^)(santa_action_t))reply;
 
 ///

Source/common/SantaCache.h

@@ -1,4 +1,4 @@
-/// Copyright 2016 Google Inc. All rights reserved.
+/// Copyright 2016-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 
 #include <libkern/OSAtomic.h>
 #include <libkern/OSTypes.h>
+#include <os/log.h>
 #include <stdint.h>
 #include <sys/cdefs.h>
 
@@ -26,11 +27,6 @@
 
 #include "Source/common/SNTCommon.h"
 
-#define panic(args...) \
-  printf(args);        \
-  printf("\n");        \
-  abort()
-
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 
@@ -334,7 +330,9 @@ class SantaCache {
   inline void unlock(struct bucket *bucket) const {
     if (unlikely(OSAtomicTestAndClear(7, (volatile uint8_t *)&bucket->head) ==
                  0)) {
-      panic("SantaCache::unlock(): Tried to unlock an unlocked lock");
+      os_log_error(OS_LOG_DEFAULT,
+                   "SantaCache::unlock(): Tried to unlock an unlocked lock");
+      abort();
     }
   }
 

Source/common/TestUtils.h

@@ -0,0 +1,60 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__COMMON__TESTUTILS_H
+#define SANTA__COMMON__TESTUTILS_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <XCTest/XCTest.h>
+#include <bsm/libbsm.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <sys/stat.h>
+
+#define NOBODY_UID ((unsigned int)-2)
+#define NOBODY_GID ((unsigned int)-2)
+
+// Bubble up googletest expectation failures to XCTest failures
+#define XCTBubbleMockVerifyAndClearExpectations(mock)              \
+  XCTAssertTrue(::testing::Mock::VerifyAndClearExpectations(mock), \
+                "Expected calls were not properly mocked")
+
+// Pretty print C string match errors
+#define XCTAssertCStringEqual(got, want)                                                      \
+  XCTAssertTrue(strcmp((got), (want)) == 0, @"\nMismatched strings.\n\t got: %s\n\twant: %s", \
+                (got), (want))
+
+// Pretty print C++ string match errors
+#define XCTAssertCppStringEqual(got, want) XCTAssertCStringEqual((got).c_str(), (want).c_str())
+
+// Helper to ensure at least `ms` milliseconds are slept, even if the sleep
+// function returns early due to interrupts.
+void SleepMS(long ms);
+
+enum class ActionType {
+  Auth,
+  Notify,
+};
+
+// Helpers to construct various ES structs
+audit_token_t MakeAuditToken(pid_t pid, pid_t pidver);
+struct stat MakeStat(ino_t ino, dev_t devno = 0);
+es_string_token_t MakeESStringToken(const char *s);
+es_file_t MakeESFile(const char *path, struct stat sb = {});
+es_process_t MakeESProcess(es_file_t *file, audit_token_t tok = {}, audit_token_t parent_tok = {});
+es_message_t MakeESMessage(es_event_type_t et, es_process_t *proc,
+                           ActionType action_type = ActionType::Notify,
+                           uint64_t future_deadline_ms = 100000);
+
+#endif

Source/common/TestUtils.mm

@@ -0,0 +1,107 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/common/TestUtils.h"
+
+#include <EndpointSecurity/ESTypes.h>
+#include <dispatch/dispatch.h>
+#include <mach/mach_time.h>
+#include <time.h>
+
+audit_token_t MakeAuditToken(pid_t pid, pid_t pidver) {
+  return audit_token_t{
+    .val =
+      {
+        0,
+        NOBODY_UID,
+        NOBODY_GID,
+        NOBODY_UID,
+        NOBODY_GID,
+        (unsigned int)pid,
+        0,
+        (unsigned int)pidver,
+      },
+  };
+}
+
+struct stat MakeStat(ino_t ino, dev_t devno) {
+  return (struct stat){
+    .st_dev = devno,
+    .st_ino = ino,
+  };
+}
+
+es_string_token_t MakeESStringToken(const char *s) {
+  return es_string_token_t{
+    .length = strlen(s),
+    .data = s,
+  };
+}
+
+es_file_t MakeESFile(const char *path, struct stat sb) {
+  return es_file_t{
+    .path = MakeESStringToken(path),
+    .path_truncated = false,
+    .stat = sb,
+  };
+}
+
+es_process_t MakeESProcess(es_file_t *file, audit_token_t tok, audit_token_t parent_tok) {
+  return es_process_t{
+    .audit_token = tok,
+    .ppid = audit_token_to_pid(parent_tok),
+    .original_ppid = audit_token_to_pid(parent_tok),
+    .executable = file,
+    .parent_audit_token = parent_tok,
+  };
+}
+
+static uint64_t AddMillisToMachTime(uint64_t ms, uint64_t machTime) {
+  static dispatch_once_t onceToken;
+  static mach_timebase_info_data_t timebase;
+
+  dispatch_once(&onceToken, ^{
+    mach_timebase_info(&timebase);
+  });
+
+  // Convert given machTime to nanoseconds
+  uint64_t nanoTime = machTime * timebase.numer / timebase.denom;
+
+  // Add the ms offset
+  nanoTime += (ms * NSEC_PER_MSEC);
+
+  // Convert back to machTime
+  return nanoTime * timebase.denom / timebase.numer;
+}
+
+es_message_t MakeESMessage(es_event_type_t et, es_process_t *proc, ActionType action_type,
+                           uint64_t future_deadline_ms) {
+  return es_message_t{
+    .deadline = AddMillisToMachTime(future_deadline_ms, mach_absolute_time()),
+    .process = proc,
+    .action_type =
+      (action_type == ActionType::Notify) ? ES_ACTION_TYPE_NOTIFY : ES_ACTION_TYPE_AUTH,
+    .event_type = et,
+  };
+}
+
+void SleepMS(long ms) {
+  struct timespec ts {
+    .tv_sec = ms / 1000, .tv_nsec = (long)((ms % 1000) * NSEC_PER_MSEC),
+  };
+
+  while (nanosleep(&ts, &ts) != 0) {
+    XCTAssertEqual(errno, EINTR);
+  }
+}

Source/common/santa.proto

@@ -1,6 +1,7 @@
 //
 // !!! WARNING !!!
-// This proto is in beta format and subject to change.
+// This proto is for demonstration purposes only and will be changing.
+// Do not rely on this format.
 //
 
 syntax = "proto3";

Source/santactl/BUILD

@@ -26,7 +26,6 @@ objc_library(
         "//:opt_build": [],
         "//conditions:default": [
             "Commands/SNTCommandBundleInfo.m",
-            "Commands/SNTCommandCacheHistogram.m",
             "Commands/SNTCommandCheckCache.m",
             "Commands/SNTCommandFlushCache.m",
         ],

Source/santactl/Commands/SNTCommandCacheHistogram.m

@@ -1,79 +0,0 @@
-/// Copyright 2018 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#ifdef DEBUG
-
-#import <Foundation/Foundation.h>
-#import <MOLXPCConnection/MOLXPCConnection.h>
-
-#import "Source/common/SNTLogging.h"
-#import "Source/common/SNTXPCControlInterface.h"
-#import "Source/santactl/SNTCommand.h"
-#import "Source/santactl/SNTCommandController.h"
-
-@interface SNTCommandCacheHistogram : SNTCommand <SNTCommandProtocol>
-@end
-
-@implementation SNTCommandCacheHistogram
-
-REGISTER_COMMAND_NAME(@"cachehistogram")
-
-+ (BOOL)requiresRoot {
-  return YES;
-}
-
-+ (BOOL)requiresDaemonConn {
-  return YES;
-}
-
-+ (NSString *)shortHelpText {
-  return @"Print a cache distribution histogram.";
-}
-
-+ (NSString *)longHelpText {
-  return (@"Prints a histogram of each bucket of the in-kernel cache\n"
-          @"  Use -g to get 'graphical' output\n"
-          @"Only available in DEBUG builds.");
-}
-
-- (void)runWithArguments:(NSArray *)arguments {
-  [[self.daemonConn remoteObjectProxy] cacheBucketCount:^(NSArray *counts) {
-    NSMutableDictionary<NSNumber *, NSNumber *> *d = [NSMutableDictionary dictionary];
-    [counts enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL *_Nonnull stop) {
-      d[obj] = @([d[obj] intValue] + 1);
-    }];
-    printf("There are %llu empty buckets\n", [d[@0] unsignedLongLongValue]);
-
-    for (NSNumber *key in [d.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
-      if ([key isEqual:@0]) continue;
-      uint64_t k = [key unsignedLongLongValue];
-      uint64_t v = [d[key] unsignedLongLongValue];
-
-      if ([[[NSProcessInfo processInfo] arguments] containsObject:@"-g"]) {
-        printf("%4llu: ", k);
-        for (uint64_t y = 0; y < v; ++y) {
-          printf("#");
-        }
-        printf("\n");
-      } else {
-        printf("%4llu bucket[s] have %llu %s\n", v, k, k > 1 ? "entries" : "entry");
-      }
-    }
-    exit(0);
-  }];
-}
-
-@end
-
-#endif

Source/santactl/Commands/SNTCommandCheckCache.m

@@ -1,4 +1,4 @@
-/// Copyright 2016 Google Inc. All rights reserved.
+/// Copyright 2016-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -62,9 +62,6 @@ REGISTER_COMMAND_NAME(@"checkcache")
                  } else if (action == ACTION_RESPOND_ALLOW_COMPILER) {
                    LOGI(@"File exists in [allowlist compiler] kernel cache");
                    exit(0);
-                 } else if (action == ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE) {
-                   LOGI(@"File exists in [allowlist pending_transitive] kernel cache");
-                   exit(0);
                  } else if (action == ACTION_UNSET) {
                    LOGE(@"File does not exist in cache");
                    exit(1);

Source/santactl/Commands/SNTCommandFileInfo.m

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -385,6 +385,7 @@ REGISTER_COMMAND_NAME(@"fileinfo")
         case SNTEventStateBlockScope: [output appendString:@" (Scope)"]; break;
         case SNTEventStateAllowCompiler: [output appendString:@" (Compiler)"]; break;
         case SNTEventStateAllowTransitive: [output appendString:@" (Transitive)"]; break;
+        case SNTEventStateBlockLongPath: [output appendString:@" (Long Path)"]; break;
 
         default: output = @"None".mutableCopy; break;
       }

Source/santactl/Commands/SNTCommandStatus.m

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2015-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -74,18 +74,14 @@ REGISTER_COMMAND_NAME(@"status")
 
   SNTConfigurator *configurator = [SNTConfigurator configurator];
 
-  BOOL cachingEnabled = [configurator enableSysxCache];
-
   // Cache status
   __block uint64_t rootCacheCount = -1, nonRootCacheCount = -1;
-  if (cachingEnabled) {
-    dispatch_group_enter(group);
-    [[self.daemonConn remoteObjectProxy] cacheCounts:^(uint64_t rootCache, uint64_t nonRootCache) {
-      rootCacheCount = rootCache;
-      nonRootCacheCount = nonRootCache;
-      dispatch_group_leave(group);
-    }];
-  }
+  dispatch_group_enter(group);
+  [[self.daemonConn remoteObjectProxy] cacheCounts:^(uint64_t rootCache, uint64_t nonRootCache) {
+    rootCacheCount = rootCache;
+    nonRootCacheCount = nonRootCache;
+    dispatch_group_leave(group);
+  }];
 
   // Database counts
   __block int64_t eventCount = -1, binaryRuleCount = -1, certRuleCount = -1, teamIDRuleCount = -1;
@@ -215,12 +211,12 @@ REGISTER_COMMAND_NAME(@"status")
         @"transitive_rules" : @(enableTransitiveRules),
       },
     } mutableCopy];
-    if (cachingEnabled) {
-      stats[@"cache"] = @{
-        @"root_cache_count" : @(rootCacheCount),
-        @"non_root_cache_count" : @(nonRootCacheCount),
-      };
-    }
+
+    stats[@"cache"] = @{
+      @"root_cache_count" : @(rootCacheCount),
+      @"non_root_cache_count" : @(nonRootCacheCount),
+    };
+
     NSData *statsData = [NSJSONSerialization dataWithJSONObject:stats
                                                         options:NSJSONWritingPrettyPrinted
                                                           error:nil];
@@ -238,11 +234,9 @@ REGISTER_COMMAND_NAME(@"status")
     printf("  %-25s | %lld  (Peak: %.2f%%)\n", "Watchdog CPU Events", cpuEvents, cpuPeak);
     printf("  %-25s | %lld  (Peak: %.2fMB)\n", "Watchdog RAM Events", ramEvents, ramPeak);
 
-    if (cachingEnabled) {
-      printf(">>> Cache Info\n");
-      printf("  %-25s | %lld\n", "Root cache count", rootCacheCount);
-      printf("  %-25s | %lld\n", "Non-root cache count", nonRootCacheCount);
-    }
+    printf(">>> Cache Info\n");
+    printf("  %-25s | %lld\n", "Root cache count", rootCacheCount);
+    printf("  %-25s | %lld\n", "Non-root cache count", nonRootCacheCount);
 
     printf(">>> Database Info\n");
     printf("  %-25s | %lld\n", "Binary Rules", binaryRuleCount);

Source/santad/DataLayer/SNTRuleTable.m

@@ -105,6 +105,7 @@ static void addPathsFromDefaultMuteSet(NSMutableSet *criticalPaths) API_AVAILABL
 
     // This is a Santa-curated list of paths to check on startup. This list will be merged
     // with the set of default muted paths from ES.
+
     NSSet *santaDefinedCriticalPaths = [NSSet setWithArray:@[
       @"/usr/libexec/trustd",
       @"/usr/lib/dyld",
@@ -136,6 +137,12 @@ static void addPathsFromDefaultMuteSet(NSMutableSet *criticalPaths) API_AVAILABL
   NSMutableDictionary *bins = [NSMutableDictionary dictionary];
   for (NSString *path in [SNTRuleTable criticalSystemBinaryPaths]) {
     SNTFileInfo *binInfo = [[SNTFileInfo alloc] initWithPath:path];
+    if (!binInfo.SHA256) {
+      // If there isn't a hash, no need to compute the other info here.
+      // Just continue on to the next binary.
+      LOGW(@"Unable to compute hash for critical system binary %@.", path);
+      continue;
+    }
     MOLCodesignChecker *csInfo = [binInfo codesignCheckerWithError:NULL];
 
     // Make sure the critical system binary is signed by the same chain as launchd/self
@@ -143,9 +150,9 @@ static void addPathsFromDefaultMuteSet(NSMutableSet *criticalPaths) API_AVAILABL
     if ([csInfo signingInformationMatches:self.launchdCSInfo]) {
       systemBin = YES;
     } else if (![csInfo signingInformationMatches:self.santadCSInfo]) {
-      LOGE(@"Unable to validate critical system binary. "
+      LOGW(@"Unable to validate critical system binary %@. "
            @"pid 1: %@, santad: %@ and %@: %@ do not match.",
-           self.launchdCSInfo.leafCertificate, self.santadCSInfo.leafCertificate, path,
+           path, self.launchdCSInfo.leafCertificate, self.santadCSInfo.leafCertificate, path,
            csInfo.leafCertificate);
       continue;
     }

Source/santad/EventProviders/AuthResultCache.h

@@ -0,0 +1,75 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_AUTHRESULTCACHE_H
+#define SANTA__SANTAD__EVENTPROVIDERS_AUTHRESULTCACHE_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <Foundation/Foundation.h>
+#include <dispatch/dispatch.h>
+#include <sys/stat.h>
+#include <memory>
+
+#import "Source/common/SNTCommon.h"
+#include "Source/common/SantaCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+
+namespace santa::santad::event_providers {
+
+enum class FlushCacheMode {
+  kNonRootOnly,
+  kAllCaches,
+};
+
+class AuthResultCache {
+ public:
+  // Santa currently only flushes caches when new DENY rules are added, not
+  // ALLOW rules. This means this value should be low enough so that if a
+  // previously denied binary is allowed, it can be re-executed by the user in a
+  // timely manner. But the value should be high enough to allow the cache to be
+  // effective in the event the binary is executed in rapid succession.
+  AuthResultCache(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi,
+    uint64_t cache_deny_time_ms = 1500);
+  virtual ~AuthResultCache();
+
+  AuthResultCache(AuthResultCache &&other) = delete;
+  AuthResultCache &operator=(AuthResultCache &&rhs) = delete;
+  AuthResultCache(const AuthResultCache &other) = delete;
+  AuthResultCache &operator=(const AuthResultCache &other) = delete;
+
+  virtual bool AddToCache(const es_file_t *es_file, santa_action_t decision);
+  virtual void RemoveFromCache(const es_file_t *es_file);
+  virtual santa_action_t CheckCache(const es_file_t *es_file);
+  virtual santa_action_t CheckCache(santa_vnode_id_t vnode_id);
+
+  virtual void FlushCache(FlushCacheMode mode);
+
+  virtual NSArray<NSNumber *> *CacheCounts();
+
+ private:
+  virtual SantaCache<santa_vnode_id_t, uint64_t> *CacheForVnodeID(santa_vnode_id_t vnode_id);
+
+  SantaCache<santa_vnode_id_t, uint64_t> *root_cache_;
+  SantaCache<santa_vnode_id_t, uint64_t> *nonroot_cache_;
+
+  std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi_;
+  uint64_t root_devno_;
+  uint64_t cache_deny_time_ns_;
+  dispatch_queue_t q_;
+};
+
+}  // namespace santa::santad::event_providers
+
+#endif

Source/santad/EventProviders/AuthResultCache.mm

@@ -0,0 +1,156 @@
+
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/EventProviders/AuthResultCache.h"
+
+#include <mach/clock_types.h>
+#include <time.h>
+
+#import "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+
+template <>
+uint64_t SantaCacheHasher<santa_vnode_id_t>(santa_vnode_id_t const &t) {
+  return (SantaCacheHasher<uint64_t>(t.fsid) << 1) ^ SantaCacheHasher<uint64_t>(t.fileid);
+}
+
+namespace santa::santad::event_providers {
+
+static inline santa_vnode_id_t VnodeForFile(const es_file_t *es_file) {
+  return santa_vnode_id_t{
+    .fsid = (uint64_t)es_file->stat.st_dev,
+    .fileid = es_file->stat.st_ino,
+  };
+}
+
+static inline uint64_t GetCurrentUptime() {
+  return clock_gettime_nsec_np(CLOCK_MONOTONIC);
+}
+
+// Decision is stored in upper 8 bits, timestamp in remaining 56.
+static inline uint64_t CacheableAction(santa_action_t action,
+                                       uint64_t timestamp = GetCurrentUptime()) {
+  return ((uint64_t)action << 56) | (timestamp & 0xFFFFFFFFFFFFFF);
+}
+
+static inline santa_action_t ActionFromCachedValue(uint64_t cachedValue) {
+  return (santa_action_t)(cachedValue >> 56);
+}
+
+static inline uint64_t TimestampFromCachedValue(uint64_t cachedValue) {
+  return (cachedValue & ~(0xFF00000000000000));
+}
+
+AuthResultCache::AuthResultCache(std::shared_ptr<EndpointSecurityAPI> esapi,
+                                 uint64_t cache_deny_time_ms)
+    : esapi_(esapi), cache_deny_time_ns_(cache_deny_time_ms * NSEC_PER_MSEC) {
+  root_cache_ = new SantaCache<santa_vnode_id_t, uint64_t>();
+  nonroot_cache_ = new SantaCache<santa_vnode_id_t, uint64_t>();
+
+  struct stat sb;
+  if (stat("/", &sb) == 0) {
+    root_devno_ = sb.st_dev;
+  }
+
+  q_ = dispatch_queue_create(
+    "com.google.santa.daemon.auth_result_cache.q",
+    dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL,
+                                            QOS_CLASS_USER_INTERACTIVE, 0));
+}
+
+AuthResultCache::~AuthResultCache() {
+  delete root_cache_;
+  delete nonroot_cache_;
+}
+
+bool AuthResultCache::AddToCache(const es_file_t *es_file, santa_action_t decision) {
+  santa_vnode_id_t vnode_id = VnodeForFile(es_file);
+  SantaCache<santa_vnode_id_t, uint64_t> *cache = CacheForVnodeID(vnode_id);
+  switch (decision) {
+    case ACTION_REQUEST_BINARY:
+      return cache->set(vnode_id, CacheableAction(ACTION_REQUEST_BINARY, 0), 0);
+    case ACTION_RESPOND_ALLOW: OS_FALLTHROUGH;
+    case ACTION_RESPOND_ALLOW_COMPILER: OS_FALLTHROUGH;
+    case ACTION_RESPOND_DENY:
+      return cache->set(vnode_id, CacheableAction(decision),
+                        CacheableAction(ACTION_REQUEST_BINARY, 0));
+    default:
+      // This is a programming error. Bail.
+      LOGE(@"Invalid cache value, exiting.");
+      exit(EXIT_FAILURE);
+  }
+}
+
+void AuthResultCache::RemoveFromCache(const es_file_t *es_file) {
+  santa_vnode_id_t vnode_id = VnodeForFile(es_file);
+  CacheForVnodeID(vnode_id)->remove(vnode_id);
+}
+
+santa_action_t AuthResultCache::CheckCache(const es_file_t *es_file) {
+  return CheckCache(VnodeForFile(es_file));
+}
+
+santa_action_t AuthResultCache::CheckCache(santa_vnode_id_t vnode_id) {
+  SantaCache<santa_vnode_id_t, uint64_t> *cache = CacheForVnodeID(vnode_id);
+
+  uint64_t cached_val = cache->get(vnode_id);
+  if (cached_val == 0) {
+    return ACTION_UNSET;
+  }
+
+  santa_action_t result = ActionFromCachedValue(cached_val);
+
+  if (result == ACTION_RESPOND_DENY) {
+    uint64_t expiry_time = TimestampFromCachedValue(cached_val) + cache_deny_time_ns_;
+    if (expiry_time < GetCurrentUptime()) {
+      cache->remove(vnode_id);
+      return ACTION_UNSET;
+    }
+  }
+
+  return result;
+}
+
+SantaCache<santa_vnode_id_t, uint64_t> *AuthResultCache::CacheForVnodeID(
+  santa_vnode_id_t vnode_id) {
+  return (vnode_id.fsid == root_devno_ || root_devno_ == 0) ? root_cache_ : nonroot_cache_;
+}
+
+void AuthResultCache::FlushCache(FlushCacheMode mode) {
+  nonroot_cache_->clear();
+  if (mode == FlushCacheMode::kAllCaches) {
+    root_cache_->clear();
+
+    // Clear the ES cache when all local caches are flushed. Assume the ES cache
+    // doesn't need to be cleared when only flushing the non-root cache.
+    //
+    // Calling into ES should be done asynchronously since it could otherwise
+    // potentially deadlock.
+    auto shared_esapi = esapi_->shared_from_this();
+    dispatch_async(q_, ^{
+      // ES does not need a connected client to clear cache
+      shared_esapi->ClearCache(Client());
+    });
+  }
+}
+
+NSArray<NSNumber *> *AuthResultCache::CacheCounts() {
+  return @[ @(root_cache_->count()), @(nonroot_cache_->count()) ];
+}
+
+}  // namespace santa::santad::event_providers

Source/santad/EventProviders/AuthResultCacheTest.mm

@@ -0,0 +1,225 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#include <Foundation/Foundation.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <time.h>
+
+#include <memory>
+
+#include "Source/common/SNTCommon.h"
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::FlushCacheMode;
+
+// Grab the st_dev number of the root volume to match the root cache
+static uint64_t RootDevno() {
+  static dispatch_once_t once_token;
+  static uint64_t devno;
+  dispatch_once(&once_token, ^{
+    struct stat sb;
+    stat("/", &sb);
+    devno = sb.st_dev;
+  });
+  return devno;
+}
+
+static inline es_file_t MakeCacheableFile(uint64_t devno, uint64_t ino) {
+  return es_file_t{
+    .path = {}, .path_truncated = false, .stat = {.st_dev = (dev_t)devno, .st_ino = ino}};
+}
+
+static inline santa_vnode_id_t VnodeForFile(const es_file_t *es_file) {
+  return santa_vnode_id_t{
+    .fsid = (uint64_t)es_file->stat.st_dev,
+    .fileid = es_file->stat.st_ino,
+  };
+}
+
+static inline void AssertCacheCounts(std::shared_ptr<AuthResultCache> cache, uint64_t root_count,
+                                     uint64_t nonroot_count) {
+  NSArray<NSNumber *> *counts = cache->CacheCounts();
+
+  XCTAssertNotNil(counts);
+  XCTAssertEqual([counts count], 2);
+  XCTAssertNotNil(counts[0]);
+  XCTAssertNotNil(counts[1]);
+  XCTAssertEqual([counts[0] unsignedLongLongValue], root_count);
+  XCTAssertEqual([counts[1] unsignedLongLongValue], nonroot_count);
+}
+
+@interface AuthResultCacheTest : XCTestCase
+@end
+
+@implementation AuthResultCacheTest
+
+- (void)testEmptyCacheExpectedNumberOfCacheCounts {
+  auto esapi = std::make_shared<MockEndpointSecurityAPI>();
+  auto cache = std::make_shared<AuthResultCache>(esapi);
+
+  AssertCacheCounts(cache, 0, 0);
+}
+
+- (void)testBasicOperation {
+  auto esapi = std::make_shared<MockEndpointSecurityAPI>();
+  auto cache = std::make_shared<AuthResultCache>(esapi);
+
+  es_file_t rootFile = MakeCacheableFile(RootDevno(), 111);
+  es_file_t nonrootFile = MakeCacheableFile(RootDevno() + 123, 222);
+
+  // Add the root file to the cache
+  cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY);
+
+  AssertCacheCounts(cache, 1, 0);
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_REQUEST_BINARY);
+  XCTAssertEqual(cache->CheckCache(&nonrootFile), ACTION_UNSET);
+
+  // Now add the non-root file
+  cache->AddToCache(&nonrootFile, ACTION_REQUEST_BINARY);
+
+  AssertCacheCounts(cache, 1, 1);
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_REQUEST_BINARY);
+  XCTAssertEqual(cache->CheckCache(&nonrootFile), ACTION_REQUEST_BINARY);
+
+  // Update the cached values
+  cache->AddToCache(&rootFile, ACTION_RESPOND_ALLOW);
+  cache->AddToCache(&nonrootFile, ACTION_RESPOND_DENY);
+
+  AssertCacheCounts(cache, 1, 1);
+  XCTAssertEqual(cache->CheckCache(VnodeForFile(&rootFile)), ACTION_RESPOND_ALLOW);
+  XCTAssertEqual(cache->CheckCache(VnodeForFile(&nonrootFile)), ACTION_RESPOND_DENY);
+
+  // Remove the root file
+  cache->RemoveFromCache(&rootFile);
+
+  AssertCacheCounts(cache, 0, 1);
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_UNSET);
+  XCTAssertEqual(cache->CheckCache(&nonrootFile), ACTION_RESPOND_DENY);
+}
+
+- (void)testFlushCache {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  auto cache = std::make_shared<AuthResultCache>(mockESApi);
+
+  es_file_t rootFile = MakeCacheableFile(RootDevno(), 111);
+  es_file_t nonrootFile = MakeCacheableFile(RootDevno() + 123, 111);
+
+  cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY);
+  cache->AddToCache(&nonrootFile, ACTION_REQUEST_BINARY);
+
+  AssertCacheCounts(cache, 1, 1);
+
+  // Flush non-root only
+  cache->FlushCache(FlushCacheMode::kNonRootOnly);
+
+  AssertCacheCounts(cache, 1, 0);
+
+  // Add back the non-root file
+  cache->AddToCache(&nonrootFile, ACTION_REQUEST_BINARY);
+
+  AssertCacheCounts(cache, 1, 1);
+
+  // Flush all caches
+  // The call to ClearCache is asynchronous. Use a semaphore to
+  // be notified when the mock is called.
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+  EXPECT_CALL(*mockESApi, ClearCache).WillOnce(testing::InvokeWithoutArgs(^() {
+    dispatch_semaphore_signal(sema);
+    return true;
+  }));
+  cache->FlushCache(FlushCacheMode::kAllCaches);
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 5 * NSEC_PER_SEC)),
+                 "ClearCache wasn't called within expected time window");
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+
+  AssertCacheCounts(cache, 0, 0);
+}
+
+- (void)testCacheStateMachine {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  auto cache = std::make_shared<AuthResultCache>(mockESApi);
+
+  es_file_t rootFile = MakeCacheableFile(RootDevno(), 111);
+
+  // Cached items must first be in the ACTION_REQUEST_BINARY state
+  XCTAssertFalse(cache->AddToCache(&rootFile, ACTION_RESPOND_ALLOW));
+  XCTAssertFalse(cache->AddToCache(&rootFile, ACTION_RESPOND_ALLOW_COMPILER));
+  XCTAssertFalse(cache->AddToCache(&rootFile, ACTION_RESPOND_DENY));
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_UNSET);
+
+  XCTAssertTrue(cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY));
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_REQUEST_BINARY);
+
+  // Items in the `ACTION_REQUEST_BINARY` state cannot reenter the same state
+  XCTAssertFalse(cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY));
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_REQUEST_BINARY);
+
+  santa_action_t allowed_transitions[] = {
+    ACTION_RESPOND_ALLOW,
+    ACTION_RESPOND_ALLOW_COMPILER,
+    ACTION_RESPOND_DENY,
+  };
+
+  for (size_t i = 0; i < sizeof(allowed_transitions) / sizeof(allowed_transitions[0]); i++) {
+    // First make sure the item doesn't exist
+    cache->RemoveFromCache(&rootFile);
+    XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_UNSET);
+
+    // Now add the item to be in the first allowed state
+    XCTAssertTrue(cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY));
+    XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_REQUEST_BINARY);
+
+    // Now assert the allowed transition
+    XCTAssertTrue(cache->AddToCache(&rootFile, allowed_transitions[i]));
+    XCTAssertEqual(cache->CheckCache(&rootFile), allowed_transitions[i]);
+  }
+}
+
+- (void)testCacheExpiry {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  // Create a cache with a lowered cache expiry value
+  uint64_t expiryMS = 250;
+  auto cache = std::make_shared<AuthResultCache>(mockESApi, expiryMS);
+
+  es_file_t rootFile = MakeCacheableFile(RootDevno(), 111);
+
+  // Add a file to the cache and put into the ACTION_RESPOND_DENY state
+  XCTAssertTrue(cache->AddToCache(&rootFile, ACTION_REQUEST_BINARY));
+  XCTAssertTrue(cache->AddToCache(&rootFile, ACTION_RESPOND_DENY));
+
+  // Ensure the file exists
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_RESPOND_DENY);
+
+  // Wait for the item to expire
+  SleepMS(expiryMS);
+
+  // Check cache counts to make sure the item still exists
+  AssertCacheCounts(cache, 1, 0);
+
+  // Now check the cache, which will remove the item
+  XCTAssertEqual(cache->CheckCache(&rootFile), ACTION_UNSET);
+  AssertCacheCounts(cache, 0, 0);
+}
+
+@end

Source/santad/EventProviders/DiskArbitrationTestUtil.h

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2021-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -50,7 +50,8 @@ typedef void (^MockDADiskAppearedCallback)(DADiskRef ref);
 @end
 
 //
-// All DiskArbitration functions used in SNTDeviceManager and shimmed out accordingly.
+// All DiskArbitration functions used in SNTEndpointSecurityDeviceManager
+// and shimmed out accordingly.
 //
 CF_EXTERN_C_BEGIN
 

Source/santad/EventProviders/EndpointSecurity/Client.h

@@ -0,0 +1,69 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_CLIENT_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_CLIENT_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+
+#include <cstddef>
+
+namespace santa::santad::event_providers::endpoint_security {
+
+class Client {
+ public:
+  explicit Client(es_client_t* client, es_new_client_result_t result)
+      : client_(client), result_(result) {}
+
+  Client() : client_(nullptr), result_(ES_NEW_CLIENT_RESULT_ERR_INTERNAL) {}
+
+  virtual ~Client() {
+    if (client_) {
+      // Special case: Not using EndpointSecurityAPI here due to circular refs.
+      es_delete_client(client_);
+    }
+  }
+
+  Client(Client&& other) {
+    client_ = other.client_;
+    result_ = other.result_;
+    other.client_ = nullptr;
+    other.result_ = ES_NEW_CLIENT_RESULT_ERR_INTERNAL;
+  }
+
+  Client& operator=(Client&& rhs) {
+    client_ = rhs.client_;
+    result_ = rhs.result_;
+    rhs.client_ = nullptr;
+    rhs.result_ = ES_NEW_CLIENT_RESULT_ERR_INTERNAL;
+    return *this;
+  }
+
+  Client(const Client& other) = delete;
+  void operator=(const Client& rhs) = delete;
+
+  inline bool IsConnected() { return result_ == ES_NEW_CLIENT_RESULT_SUCCESS; }
+
+  inline es_new_client_result_t NewClientResult() { return result_; }
+
+  inline es_client_t* Get() const { return client_; }
+
+ private:
+  es_client_t* client_;
+  es_new_client_result_t result_;
+};
+
+}  // namespace santa::santad::event_providers::endpoint_security
+
+#endif

Source/santad/EventProviders/EndpointSecurity/ClientTest.mm

@@ -0,0 +1,118 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <dispatch/dispatch.h>
+
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+
+// Global semaphore used for custom `es_delete_client` function
+dispatch_semaphore_t gSema;
+
+// Note: The Client class does not use the `EndpointSecurityAPI` wrappers due
+// to circular dependency issues. It is a special case that uses the underlying
+// ES API `es_delete_client` directly. This test override will signal the
+// `gSema` semaphore to indicate it has been called.
+es_return_t es_delete_client(es_client_t *_Nullable client) {
+  dispatch_semaphore_signal(gSema);
+  return ES_RETURN_SUCCESS;
+};
+
+@interface ClientTest : XCTestCase
+@end
+
+@implementation ClientTest
+
+- (void)setUp {
+  gSema = dispatch_semaphore_create(0);
+}
+
+- (void)testConstructorsAndDestructors {
+  // Ensure constructors set internal state properly
+  // Anonymous scopes used to ensure destructors called as expected
+
+  // Null `es_client_t*` *shouldn't* trigger `es_delete_client`
+  {
+    Client c;
+    XCTAssertEqual(c.Get(), nullptr);
+    XCTAssertEqual(c.NewClientResult(), ES_NEW_CLIENT_RESULT_ERR_INTERNAL);
+  }
+
+  XCTAssertNotEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                    "es_delete_client called unexpectedly");
+
+  // Nonnull `es_client_t*` *should* trigger `es_delete_client`
+  {
+    int fake;
+    es_client_t *fakeClient = (es_client_t *)&fake;
+    Client c(fakeClient, ES_NEW_CLIENT_RESULT_SUCCESS);
+    XCTAssertEqual(c.Get(), fakeClient);
+    XCTAssertEqual(c.NewClientResult(), ES_NEW_CLIENT_RESULT_SUCCESS);
+  }
+
+  XCTAssertEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                 "es_delete_client not called within expected time window");
+
+  // Test move constructor
+  {
+    int fake;
+    es_client_t *fakeClient = (es_client_t *)&fake;
+    Client c1(fakeClient, ES_NEW_CLIENT_RESULT_SUCCESS);
+
+    Client c2(std::move(c1));
+
+    XCTAssertEqual(c1.Get(), nullptr);
+    XCTAssertEqual(c2.Get(), fakeClient);
+    XCTAssertEqual(c2.NewClientResult(), ES_NEW_CLIENT_RESULT_SUCCESS);
+  }
+
+  // Ensure `es_delete_client` was only called once when both `c1` and `c2`
+  // are destructed.
+  XCTAssertEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                 "es_delete_client not called within expected time window");
+  XCTAssertNotEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                    "es_delete_client called unexpectedly");
+
+  // Test move assignment
+  {
+    int fake;
+    es_client_t *fakeClient = (es_client_t *)&fake;
+    Client c1(fakeClient, ES_NEW_CLIENT_RESULT_SUCCESS);
+    Client c2;
+
+    c2 = std::move(c1);
+
+    XCTAssertEqual(c1.Get(), nullptr);
+    XCTAssertEqual(c2.Get(), fakeClient);
+    XCTAssertEqual(c2.NewClientResult(), ES_NEW_CLIENT_RESULT_SUCCESS);
+  }
+
+  // Ensure `es_delete_client` was only called once when both `c1` and `c2`
+  // are destructed.
+  XCTAssertEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                 "es_delete_client not called within expected time window");
+  XCTAssertNotEqual(0, dispatch_semaphore_wait(gSema, DISPATCH_TIME_NOW),
+                    "es_delete_client called unexpectedly");
+}
+
+- (void)testIsConnected {
+  XCTAssertFalse(Client().IsConnected());
+  XCTAssertFalse(Client(nullptr, ES_NEW_CLIENT_RESULT_ERR_NOT_ENTITLED).IsConnected());
+  XCTAssertTrue(Client(nullptr, ES_NEW_CLIENT_RESULT_SUCCESS).IsConnected());
+}
+
+@end

Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h

@@ -0,0 +1,52 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENDPOINTSECURITYAPI_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENDPOINTSECURITYAPI_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <Foundation/Foundation.h>
+
+#include <set>
+
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+namespace santa::santad::event_providers::endpoint_security {
+
+class EndpointSecurityAPI : public std::enable_shared_from_this<EndpointSecurityAPI> {
+ public:
+  virtual ~EndpointSecurityAPI() = default;
+
+  virtual Client NewClient(void (^message_handler)(es_client_t *, Message));
+
+  virtual bool Subscribe(const Client &client, const std::set<es_event_type_t> &);
+
+  virtual es_message_t *RetainMessage(const es_message_t *msg);
+  virtual void ReleaseMessage(es_message_t *msg);
+
+  virtual bool RespondAuthResult(const Client &client, const Message &msg, es_auth_result_t result,
+                                 bool cache);
+
+  virtual bool MuteProcess(const Client &client, const audit_token_t *tok);
+
+  virtual bool ClearCache(const Client &client);
+
+  virtual uint32_t ExecArgCount(const es_event_exec_t *event);
+  virtual es_string_token_t ExecArg(const es_event_exec_t *event, uint32_t index);
+};
+
+}  // namespace santa::santad::event_providers::endpoint_security
+
+#endif

Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.mm

@@ -0,0 +1,87 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include <EndpointSecurity/ESTypes.h>
+
+#include <set>
+#include <vector>
+
+namespace santa::santad::event_providers::endpoint_security {
+
+Client EndpointSecurityAPI::NewClient(void (^message_handler)(es_client_t *, Message)) {
+  es_client_t *client = NULL;
+
+  auto shared_esapi = shared_from_this();
+  es_new_client_result_t res = es_new_client(&client, ^(es_client_t *c, const es_message_t *msg) {
+    @autoreleasepool {
+      message_handler(c, Message(shared_esapi, msg));
+    }
+  });
+
+  return Client(client, res);
+}
+
+es_message_t *EndpointSecurityAPI::RetainMessage(const es_message_t *msg) {
+  if (@available(macOS 11.0, *)) {
+    es_retain_message(msg);
+    es_message_t *nonconst = const_cast<es_message_t *>(msg);
+    return nonconst;
+  } else {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+    return es_copy_message(msg);
+#pragma clang diagnostic pop
+  }
+}
+
+void EndpointSecurityAPI::ReleaseMessage(es_message_t *msg) {
+  if (@available(macOS 11.0, *)) {
+    es_release_message(msg);
+  } else {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+    return es_free_message(msg);
+#pragma clang diagnostic pop
+  }
+}
+
+bool EndpointSecurityAPI::Subscribe(const Client &client,
+                                    const std::set<es_event_type_t> &event_types) {
+  std::vector<es_event_type_t> subs(event_types.begin(), event_types.end());
+  return es_subscribe(client.Get(), subs.data(), (uint32_t)subs.size()) == ES_RETURN_SUCCESS;
+}
+
+bool EndpointSecurityAPI::RespondAuthResult(const Client &client, const Message &msg,
+                                            es_auth_result_t result, bool cache) {
+  return es_respond_auth_result(client.Get(), &(*msg), result, cache) == ES_RESPOND_RESULT_SUCCESS;
+}
+
+bool EndpointSecurityAPI::MuteProcess(const Client &client, const audit_token_t *tok) {
+  return es_mute_process(client.Get(), tok) == ES_RETURN_SUCCESS;
+}
+
+bool EndpointSecurityAPI::ClearCache(const Client &client) {
+  return es_clear_cache(client.Get()) == ES_CLEAR_CACHE_RESULT_SUCCESS;
+}
+
+uint32_t EndpointSecurityAPI::ExecArgCount(const es_event_exec_t *event) {
+  return es_exec_arg_count(event);
+}
+
+es_string_token_t EndpointSecurityAPI::ExecArg(const es_event_exec_t *event, uint32_t index) {
+  return es_exec_arg(event, index);
+}
+
+}  // namespace santa::santad::event_providers::endpoint_security

Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h

@@ -0,0 +1,214 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+/// This file groups all of the enriched message types - that is the
+/// objects that are constructed to hold all enriched event data prior
+/// to being logged.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENRICHEDTYPES_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENRICHEDTYPES_H
+
+#include <time.h>
+#include <uuid/uuid.h>
+
+#include <optional>
+#include <string>
+#include <variant>
+
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+namespace santa::santad::event_providers::endpoint_security {
+
+class EnrichedFile {
+ public:
+  EnrichedFile(std::optional<std::shared_ptr<std::string>> &&user,
+               std::optional<std::shared_ptr<std::string>> &&group,
+               std::optional<std::shared_ptr<std::string>> &&hash)
+      : user_(std::move(user)),
+        group_(std::move(group)),
+        hash_(std::move(hash)) {}
+
+ private:
+  std::optional<std::shared_ptr<std::string>> user_;
+  std::optional<std::shared_ptr<std::string>> group_;
+  std::optional<std::shared_ptr<std::string>> hash_;
+};
+
+class EnrichedProcess {
+ public:
+  EnrichedProcess(std::optional<std::shared_ptr<std::string>> &&effective_user,
+                  std::optional<std::shared_ptr<std::string>> &&effective_group,
+                  std::optional<std::shared_ptr<std::string>> &&real_user,
+                  std::optional<std::shared_ptr<std::string>> &&real_group,
+                  EnrichedFile &&executable)
+      : effective_user_(std::move(effective_user)),
+        effective_group_(std::move(effective_group)),
+        real_user_(std::move(real_user)),
+        real_group_(std::move(real_group)),
+        executable_(std::move(executable)) {}
+
+  const std::optional<std::shared_ptr<std::string>> &real_user() const {
+    return real_user_;
+  }
+  const std::optional<std::shared_ptr<std::string>> &real_group() const {
+    return real_group_;
+  }
+
+ private:
+  std::optional<std::shared_ptr<std::string>> effective_user_;
+  std::optional<std::shared_ptr<std::string>> effective_group_;
+  std::optional<std::shared_ptr<std::string>> real_user_;
+  std::optional<std::shared_ptr<std::string>> real_group_;
+  EnrichedFile executable_;
+};
+
+class EnrichedEventType {
+ public:
+  EnrichedEventType(Message &&es_msg, EnrichedProcess &&instigator)
+      : es_msg_(std::move(es_msg)), instigator_(std::move(instigator)) {}
+
+  EnrichedEventType(EnrichedEventType &&other)
+      : es_msg_(std::move(other.es_msg_)),
+        instigator_(std::move(other.instigator_)) {}
+
+  virtual ~EnrichedEventType() = default;
+
+  const es_message_t &es_msg() const { return *es_msg_; }
+
+  const EnrichedProcess &instigator() const { return instigator_; }
+
+ private:
+  Message es_msg_;
+  EnrichedProcess instigator_;
+};
+
+class EnrichedClose : public EnrichedEventType {
+ public:
+  EnrichedClose(Message &&es_msg, EnrichedProcess &&instigator,
+                EnrichedFile &&target)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        target_(std::move(target)) {}
+
+ private:
+  EnrichedFile target_;
+};
+
+class EnrichedExchange : public EnrichedEventType {
+ public:
+  EnrichedExchange(Message &&es_msg, EnrichedProcess &&instigator,
+                   EnrichedFile &&file1, EnrichedFile &&file2)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        file1_(std::move(file1)),
+        file2_(std::move(file2)) {}
+
+ private:
+  EnrichedFile file1_;
+  EnrichedFile file2_;
+};
+
+class EnrichedExec : public EnrichedEventType {
+ public:
+  EnrichedExec(Message &&es_msg, EnrichedProcess &&instigator,
+               EnrichedProcess &&target, std::optional<EnrichedFile> &&script,
+               std::optional<EnrichedFile> working_dir)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        target_(std::move(target)),
+        script_(std::move(script)),
+        working_dir_(std::move(working_dir)) {}
+
+ private:
+  EnrichedProcess target_;
+  std::optional<EnrichedFile> script_;
+  std::optional<EnrichedFile> working_dir_;
+};
+
+class EnrichedExit : public EnrichedEventType {
+ public:
+  EnrichedExit(Message &&es_msg, EnrichedProcess &&instigator)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)) {}
+};
+
+class EnrichedFork : public EnrichedEventType {
+ public:
+  EnrichedFork(Message &&es_msg, EnrichedProcess &&instigator,
+               EnrichedProcess &&target)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        target_(std::move(target)) {}
+
+ private:
+  EnrichedProcess target_;
+};
+
+class EnrichedLink : public EnrichedEventType {
+ public:
+  EnrichedLink(Message &&es_msg, EnrichedProcess &&instigator,
+               EnrichedFile &&source, EnrichedFile &&target_dir)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        source_(std::move(source)),
+        target_dir_(std::move(target_dir)) {}
+
+ private:
+  EnrichedFile source_;
+  EnrichedFile target_dir_;
+};
+
+class EnrichedRename : public EnrichedEventType {
+ public:
+  EnrichedRename(Message &&es_msg, EnrichedProcess &&instigator,
+                 EnrichedFile &&source, std::optional<EnrichedFile> &&target,
+                 std::optional<EnrichedFile> &&target_dir)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        source_(std::move(source)),
+        target_(std::move(target)),
+        target_dir_(std::move(target_dir)) {}
+
+ private:
+  EnrichedFile source_;
+  std::optional<EnrichedFile> target_;
+  std::optional<EnrichedFile> target_dir_;
+};
+
+class EnrichedUnlink : public EnrichedEventType {
+ public:
+  EnrichedUnlink(Message &&es_msg, EnrichedProcess &&instigator,
+                 EnrichedFile &&target)
+      : EnrichedEventType(std::move(es_msg), std::move(instigator)),
+        target_(std::move(target)) {}
+
+ private:
+  EnrichedFile target_;
+};
+
+using EnrichedType =
+    std::variant<EnrichedClose, EnrichedExchange, EnrichedExec, EnrichedExit,
+                 EnrichedFork, EnrichedLink, EnrichedRename, EnrichedUnlink>;
+
+class EnrichedMessage {
+ public:
+  EnrichedMessage(EnrichedType &&msg) : msg_(std::move(msg)) {
+    uuid_generate(uuid_);
+    clock_gettime(CLOCK_REALTIME, &enrichment_time_);
+  }
+
+  const EnrichedType &GetEnrichedMessage() { return msg_; }
+
+ private:
+  uuid_t uuid_;
+  struct timespec enrichment_time_;
+  EnrichedType msg_;
+};
+
+}  // namespace santa::santad::event_providers::endpoint_security
+
+#endif

Source/santad/EventProviders/EndpointSecurity/Enricher.h

@@ -0,0 +1,44 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENRICHER_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_ENRICHER_H
+
+#include <memory>
+
+#include "Source/common/SantaCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+
+namespace santa::santad::event_providers::endpoint_security {
+
+class Enricher {
+ public:
+  Enricher();
+  virtual ~Enricher() = default;
+  virtual std::shared_ptr<EnrichedMessage> Enrich(Message &&msg);
+  virtual EnrichedProcess Enrich(const es_process_t &es_proc);
+  virtual EnrichedFile Enrich(const es_file_t &es_file);
+
+  virtual std::optional<std::shared_ptr<std::string>> UsernameForUID(uid_t uid);
+  virtual std::optional<std::shared_ptr<std::string>> UsernameForGID(gid_t gid);
+
+ private:
+  SantaCache<uid_t, std::optional<std::shared_ptr<std::string>>>
+      username_cache_;
+  SantaCache<gid_t, std::optional<std::shared_ptr<std::string>>>
+      groupname_cache_;
+};
+
+}  // namespace santa::santad::event_providers::endpoint_security
+
+#endif

Source/santad/EventProviders/EndpointSecurity/Enricher.mm

@@ -0,0 +1,137 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+
+#include <EndpointSecurity/ESTypes.h>
+#include <bsm/libbsm.h>
+#include <grp.h>
+#include <pwd.h>
+#include <sys/types.h>
+#include <uuid/uuid.h>
+
+#include <memory>
+#include <optional>
+
+#include "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+
+namespace santa::santad::event_providers::endpoint_security {
+
+Enricher::Enricher() : username_cache_(256), groupname_cache_(256) {}
+
+std::shared_ptr<EnrichedMessage> Enricher::Enrich(Message &&es_msg) {
+  // TODO(mlw): Consider potential design patterns that could help reduce memory usage under load
+  // (such as maybe the flyweight pattern)
+  switch (es_msg->event_type) {
+    case ES_EVENT_TYPE_NOTIFY_CLOSE:
+      return std::make_shared<EnrichedMessage>(EnrichedClose(
+        std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.close.target)));
+    case ES_EVENT_TYPE_NOTIFY_EXCHANGEDATA:
+      return std::make_shared<EnrichedMessage>(EnrichedExchange(
+        std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.exchangedata.file1),
+        Enrich(*es_msg->event.exchangedata.file2)));
+    case ES_EVENT_TYPE_NOTIFY_EXEC:
+      return std::make_shared<EnrichedMessage>(EnrichedExec(
+        std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.exec.target),
+        (es_msg->version >= 2 && es_msg->event.exec.script)
+          ? std::make_optional(Enrich(*es_msg->event.exec.script))
+          : std::nullopt,
+        (es_msg->version >= 3) ? std::make_optional(Enrich(*es_msg->event.exec.cwd))
+                               : std::nullopt));
+    case ES_EVENT_TYPE_NOTIFY_FORK:
+      return std::make_shared<EnrichedMessage>(EnrichedFork(
+        std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.fork.child)));
+    case ES_EVENT_TYPE_NOTIFY_EXIT:
+      return std::make_shared<EnrichedMessage>(
+        EnrichedExit(std::move(es_msg), Enrich(*es_msg->process)));
+    case ES_EVENT_TYPE_NOTIFY_LINK:
+      return std::make_shared<EnrichedMessage>(
+        EnrichedLink(std::move(es_msg), Enrich(*es_msg->process),
+                     Enrich(*es_msg->event.link.source), Enrich(*es_msg->event.link.target_dir)));
+    case ES_EVENT_TYPE_NOTIFY_RENAME: {
+      if (es_msg->event.rename.destination_type == ES_DESTINATION_TYPE_NEW_PATH) {
+        return std::make_shared<EnrichedMessage>(EnrichedRename(
+          std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.rename.source),
+          std::nullopt, Enrich(*es_msg->event.rename.destination.new_path.dir)));
+      } else {
+        return std::make_shared<EnrichedMessage>(EnrichedRename(
+          std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.rename.source),
+          Enrich(*es_msg->event.rename.destination.existing_file), std::nullopt));
+      }
+    }
+    case ES_EVENT_TYPE_NOTIFY_UNLINK:
+      return std::make_shared<EnrichedMessage>(EnrichedUnlink(
+        std::move(es_msg), Enrich(*es_msg->process), Enrich(*es_msg->event.unlink.target)));
+    default:
+      // This is a programming error
+      LOGE(@"Attempting to enrich an unhandled event type: %d", es_msg->event_type);
+      exit(EXIT_FAILURE);
+  }
+}
+
+EnrichedProcess Enricher::Enrich(const es_process_t &es_proc) {
+  return EnrichedProcess(UsernameForUID(audit_token_to_euid(es_proc.audit_token)),
+                         UsernameForGID(audit_token_to_egid(es_proc.audit_token)),
+                         UsernameForUID(audit_token_to_ruid(es_proc.audit_token)),
+                         UsernameForGID(audit_token_to_rgid(es_proc.audit_token)),
+                         Enrich(*es_proc.executable));
+}
+
+EnrichedFile Enricher::Enrich(const es_file_t &es_file) {
+  // TODO(mlw): Consider having the enricher perform file hashing. This will
+  // make more sense if we start including hashes in more event types.
+  return EnrichedFile(UsernameForUID(es_file.stat.st_uid), UsernameForGID(es_file.stat.st_gid),
+                      std::nullopt);
+}
+
+std::optional<std::shared_ptr<std::string>> Enricher::UsernameForUID(uid_t uid) {
+  std::optional<std::shared_ptr<std::string>> username = username_cache_.get(uid);
+
+  if (username.has_value()) {
+    return username;
+  } else {
+    struct passwd *pw = getpwuid(uid);
+    if (pw) {
+      username = std::make_shared<std::string>(pw->pw_name);
+    } else {
+      username = std::nullopt;
+    }
+
+    username_cache_.set(uid, username);
+
+    return username;
+  }
+}
+
+std::optional<std::shared_ptr<std::string>> Enricher::UsernameForGID(gid_t gid) {
+  std::optional<std::shared_ptr<std::string>> groupname = groupname_cache_.get(gid);
+
+  if (groupname.has_value()) {
+    return groupname;
+  } else {
+    struct group *gr = getgrgid(gid);
+    if (gr) {
+      groupname = std::make_shared<std::string>(gr->gr_name);
+    } else {
+      groupname = std::nullopt;
+    }
+
+    groupname_cache_.set(gid, groupname);
+
+    return groupname;
+  }
+}
+
+}  // namespace santa::santad::event_providers::endpoint_security

Source/santad/EventProviders/EndpointSecurity/EnricherTest.mm

@@ -0,0 +1,49 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+
+using santa::santad::event_providers::endpoint_security::Enricher;
+
+@interface EnricherTest : XCTestCase
+@end
+
+@implementation EnricherTest
+
+- (void)testUidGid {
+  Enricher enricher;
+
+  std::optional<std::shared_ptr<std::string>> user = enricher.UsernameForUID(NOBODY_UID);
+  XCTAssertTrue(user.has_value());
+  XCTAssertEqual(strcmp(user->get()->c_str(), "nobody"), 0);
+
+  std::optional<std::shared_ptr<std::string>> group = enricher.UsernameForGID(NOBODY_GID);
+  XCTAssertTrue(group.has_value());
+  XCTAssertEqual(strcmp(group->get()->c_str(), "nobody"), 0);
+
+  uid_t invalidUID = (uid_t)-123;
+  gid_t invalidGID = (gid_t)-123;
+
+  std::optional<std::shared_ptr<std::string>> invalidUser = enricher.UsernameForUID(invalidUID);
+  XCTAssertFalse(invalidUser.has_value());
+
+  std::optional<std::shared_ptr<std::string>> invalidGroup = enricher.UsernameForGID(invalidGID);
+  XCTAssertFalse(invalidGroup.has_value());
+}
+
+@end

Source/santad/EventProviders/EndpointSecurity/Message.h

@@ -0,0 +1,60 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_MESSAGE_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_MESSAGE_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+
+#include <memory>
+#include <string>
+
+namespace santa::santad::event_providers::endpoint_security {
+
+class EndpointSecurityAPI;
+
+class Message {
+ public:
+  Message(std::shared_ptr<EndpointSecurityAPI> esapi,
+          const es_message_t* es_msg);
+  ~Message();
+
+  Message(Message&& other);
+  // Note: Safe to implement this, just not currently needed so left deleted.
+  Message& operator=(Message&& rhs) = delete;
+
+  // In macOS 10.15, es_retain_message/es_release_message were unsupported
+  // and required a full copy, which impacts performance if done too much...
+  Message(const Message& other);
+  Message& operator=(const Message& other) = delete;
+
+  // Operators to access underlying es_message_t
+  const es_message_t* operator->() const { return es_msg_; }
+  const es_message_t& operator*() const { return *es_msg_; }
+
+  std::string ParentProcessName() const;
+
+ private:
+  std::shared_ptr<EndpointSecurityAPI> esapi_;
+  es_message_t* es_msg_;
+
+  mutable std::string pname_;
+  mutable std::string parent_pname_;
+
+  std::string GetProcessName(pid_t pid) const;
+};
+
+}  // namespace santa::santad::event_providers::endpoint_security
+
+#endif

Source/santad/EventProviders/EndpointSecurity/Message.mm

@@ -0,0 +1,65 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+#include <bsm/libbsm.h>
+#include <libproc.h>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+
+namespace santa::santad::event_providers::endpoint_security {
+
+Message::Message(std::shared_ptr<EndpointSecurityAPI> esapi, const es_message_t *es_msg)
+    : esapi_(esapi) {
+  es_msg_ = esapi_->RetainMessage(es_msg);
+}
+
+Message::~Message() {
+  if (es_msg_) {
+    esapi_->ReleaseMessage(es_msg_);
+  }
+}
+
+Message::Message(Message &&other) {
+  esapi_ = std::move(other.esapi_);
+  es_msg_ = other.es_msg_;
+  other.es_msg_ = nullptr;
+}
+
+Message::Message(const Message &other) {
+  esapi_ = other.esapi_;
+  es_msg_ = other.es_msg_;
+  esapi_->RetainMessage(es_msg_);
+}
+
+std::string Message::ParentProcessName() const {
+  if (parent_pname_.length() == 0) {
+    parent_pname_ = GetProcessName(es_msg_->process->ppid);
+  }
+  return parent_pname_;
+}
+
+std::string Message::GetProcessName(pid_t pid) const {
+  // Note: proc_name() accesses the `pbi_name` field of `struct proc_bsdinfo`. The size of `pname`
+  // here is meant to match the size of `pbi_name`, and one extra byte ensure zero-terminated.
+  char pname[MAXCOMLEN * 2 + 1] = {};
+  if (proc_name(pid, pname, sizeof(pname)) > 0) {
+    return std::string(pname);
+  } else {
+    return std::string("");
+  }
+}
+
+}  // namespace santa::santad::event_providers::endpoint_security

Source/santad/EventProviders/EndpointSecurity/MessageTest.mm

@@ -0,0 +1,135 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <libproc.h>
+#include <stdlib.h>
+
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+
+using santa::santad::event_providers::endpoint_security::Message;
+
+bool IsPidInUse(pid_t pid) {
+  char pname[MAXCOMLEN * 2 + 1] = {};
+  errno = 0;
+  if (proc_name(pid, pname, sizeof(pname)) <= 0 && errno == ESRCH) {
+    return false;
+  }
+
+  // The PID may or may not actually be in use, but assume it is
+  return true;
+}
+
+// Try to find an unused PID by looking for libproc returning ESRCH errno.
+// Start searching backwards from PID_MAX to increase likelyhood that the
+// returned PID will still be unused by the time it's being used.
+// TODO(mlw): Alternatively, we could inject the `proc_name` function into
+// the `Message` object to remove the guesswork here.
+pid_t AttemptToFindUnusedPID() {
+  for (pid_t pid = 99999 /* PID_MAX */; pid > 1; pid--) {
+    if (!IsPidInUse(pid)) {
+      return pid;
+    }
+  }
+
+  return 0;
+}
+
+@interface MessageTest : XCTestCase
+@end
+
+@implementation MessageTest
+
+- (void)setUp {
+}
+
+- (void)testConstructorsAndDestructors {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXIT, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  // Constructing a `Message` retains the underlying `es_message_t` and it is
+  // released when the `Message` object is destructed.
+  { Message m(mockESApi, &esMsg); }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testCopyConstructor {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXIT, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  EXPECT_CALL(*mockESApi, ReleaseMessage(testing::_))
+    .Times(2)
+    .After(EXPECT_CALL(*mockESApi, RetainMessage(testing::_))
+             .Times(2)
+             .WillRepeatedly(testing::Return(&esMsg)));
+
+  {
+    Message msg1(mockESApi, &esMsg);
+    Message msg2(msg1);
+
+    // Both messages should now point to the same `es_message_t`
+    XCTAssertEqual(msg1.operator->(), &esMsg);
+    XCTAssertEqual(msg2.operator->(), &esMsg);
+  }
+
+  // Ensure the retain/release mocks were called the expected number of times
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testGetParentProcessName {
+  // Construct a message where the parent pid is ourself
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(getpid(), 0));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXIT, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  // Search for an *existing* parent process.
+  {
+    Message msg(mockESApi, &esMsg);
+
+    std::string got = msg.ParentProcessName();
+    std::string want = getprogname();
+
+    XCTAssertCppStringEqual(got, want);
+  }
+
+  // Search for a *non-existent* parent process.
+  {
+    pid_t newPpid = AttemptToFindUnusedPID();
+    proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(newPpid, 34));
+
+    Message msg(mockESApi, &esMsg);
+
+    std::string got = msg.ParentProcessName();
+    std::string want = "";
+
+    XCTAssertCppStringEqual(got, want);
+  }
+}
+
+@end

Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h

@@ -0,0 +1,75 @@
+/// Copyright 2021 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_MOCKENDPOINTSECURITYAPI_H
+#define SANTA__SANTAD__EVENTPROVIDERS_ENDPOINTSECURITY_MOCKENDPOINTSECURITYAPI_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <Foundation/Foundation.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <set>
+
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+
+class MockEndpointSecurityAPI
+    : public santa::santad::event_providers::endpoint_security::EndpointSecurityAPI {
+ public:
+  MOCK_METHOD(santa::santad::event_providers::endpoint_security::Client, NewClient,
+              (void (^message_handler)(
+                es_client_t *, santa::santad::event_providers::endpoint_security::Message)));
+
+  MOCK_METHOD(bool, Subscribe,
+              (const santa::santad::event_providers::endpoint_security::Client &,
+               const std::set<es_event_type_t> &));
+
+  MOCK_METHOD(es_message_t *, RetainMessage, (const es_message_t *msg));
+  MOCK_METHOD(void, ReleaseMessage, (es_message_t * msg));
+
+  MOCK_METHOD(bool, RespondAuthResult,
+              (const santa::santad::event_providers::endpoint_security::Client &,
+               const santa::santad::event_providers::endpoint_security::Message &msg,
+               es_auth_result_t result, bool cache));
+
+  MOCK_METHOD(bool, MuteProcess,
+              (const santa::santad::event_providers::endpoint_security::Client &,
+               const audit_token_t *tok));
+
+  MOCK_METHOD(bool, ClearCache,
+              (const santa::santad::event_providers::endpoint_security::Client &));
+
+  MOCK_METHOD(uint32_t, ExecArgCount, (const es_event_exec_t *event));
+  MOCK_METHOD(es_string_token_t, ExecArg, (const es_event_exec_t *event, uint32_t index));
+
+  void SetExpectationsESNewClient() {
+    EXPECT_CALL(*this, NewClient)
+      .WillOnce(testing::Return(santa::santad::event_providers::endpoint_security::Client(
+        nullptr, ES_NEW_CLIENT_RESULT_SUCCESS)));
+    EXPECT_CALL(*this, MuteProcess).WillOnce(testing::Return(true));
+    EXPECT_CALL(*this, ClearCache).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(*this, Subscribe).WillRepeatedly(testing::Return(true));
+  }
+
+  void SetExpectationsRetainReleaseMessage(es_message_t *msg) {
+    EXPECT_CALL(*this, ReleaseMessage).Times(testing::AnyNumber());
+    EXPECT_CALL(*this, RetainMessage).WillRepeatedly(testing::Return(msg));
+  }
+};
+
+#endif

Source/santad/EventProviders/EndpointSecurityTestUtil.h

@@ -1,104 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#include <EndpointSecurity/EndpointSecurity.h>
-#include <Foundation/Foundation.h>
-#include <bsm/libbsm.h>
-
-CF_EXTERN_C_BEGIN
-es_string_token_t MakeStringToken(const NSString *_Nonnull s);
-
-es_file_t MakeESFile(const char *_Nonnull path);
-es_process_t MakeESProcess(es_file_t *_Nonnull esFile);
-es_message_t MakeESMessage(es_event_type_t eventType, es_process_t *_Nonnull instigator,
-                           struct timespec ts);
-CF_EXTERN_C_END
-
-@class ESMessage;
-typedef void (^ESMessageBuilderBlock)(ESMessage *_Nonnull builder);
-
-// An ObjC builder wrapper around es_message_t
-@interface ESMessage : NSObject
-@property(nonatomic, readwrite, strong) NSString *_Nullable binaryPath;
-@property(nonatomic, readwrite) es_file_t *_Nonnull executable;
-@property(nonatomic, readwrite) es_process_t *_Nonnull process;
-@property(nonatomic, readwrite) es_message_t *_Nonnull message;
-@property(nonatomic, readonly) pid_t pid;
-
-- (instancetype _Nonnull)initWithBlock:(ESMessageBuilderBlock _Nullable)block
-  NS_DESIGNATED_INITIALIZER;
-@end
-
-@interface ESResponse : NSObject
-@property(nonatomic) es_auth_result_t result;
-@property(nonatomic) bool shouldCache;
-@end
-
-typedef void (^ESCallback)(ESResponse *_Nonnull);
-
-// Singleton wrapper around all of the kernel-level EndpointSecurity framework functions.
-@interface MockEndpointSecurity : NSObject
-@property NSMutableArray *_Nonnull subscriptions;
-- (void)reset;
-- (void)registerResponseCallback:(es_event_type_t)t withCallback:(ESCallback _Nonnull)callback;
-- (void)triggerHandler:(es_message_t *_Nonnull)msg;
-
-///  Retrieve an initialized singleton MockEndpointSecurity object
-+ (instancetype _Nonnull)mockEndpointSecurity;
-@end
-
-API_UNAVAILABLE(ios, tvos, watchos)
-es_message_t *_Nullable es_copy_message(const es_message_t *_Nonnull msg);
-
-API_UNAVAILABLE(ios, tvos, watchos)
-void es_free_message(es_message_t *_Nonnull msg);
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_new_client_result_t es_new_client(es_client_t *_Nullable *_Nonnull client,
-                                     es_handler_block_t _Nonnull handler);
-
-API_AVAILABLE(macos(10.15)) API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_mute_process(es_client_t * _Nonnull client,
-                            const audit_token_t * _Nonnull audit_token);
-
-#if defined(MAC_OS_VERSION_12_0) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_12_0
-API_AVAILABLE(macos(12.0))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_muted_paths_events(es_client_t *_Nonnull client,
-                                  es_muted_paths_t *_Nonnull *_Nullable muted_paths);
-
-API_AVAILABLE(macos(12.0))
-API_UNAVAILABLE(ios, tvos, watchos)
-void es_release_muted_paths(es_muted_paths_t *_Nonnull muted_paths);
-#endif
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_respond_result_t es_respond_auth_result(es_client_t *_Nonnull client,
-                                           const es_message_t *_Nonnull message,
-                                           es_auth_result_t result, bool cache);
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_subscribe(es_client_t *_Nonnull client, const es_event_type_t *_Nonnull events,
-                         uint32_t event_count);
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos) es_return_t es_delete_client(es_client_t *_Nullable client);
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_unsubscribe(es_client_t *_Nonnull client, const es_event_type_t *_Nonnull events,
-                           uint32_t event_count);

Source/santad/EventProviders/EndpointSecurityTestUtil.mm

@@ -1,367 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-#import <Foundation/Foundation.h>
-
-#include <EndpointSecurity/EndpointSecurity.h>
-#include <bsm/libbsm.h>
-#include <stdlib.h>
-
-#import "Source/santad/EventProviders/EndpointSecurityTestUtil.h"
-
-CF_EXTERN_C_BEGIN
-es_string_token_t MakeStringToken(const NSString *_Nonnull s) {
-  return (es_string_token_t){
-    .length = [s length],
-    .data = [s UTF8String],
-  };
-}
-
-es_file_t MakeESFile(const char *path) {
-  es_file_t esFile = {};
-
-  esFile.path.data = path;
-  esFile.path.length = strlen(path);
-  esFile.path_truncated = false;
-
-  // Note: stat info is currently unused / not populated
-
-  return esFile;
-}
-
-es_process_t MakeESProcess(es_file_t *esFile) {
-  es_process_t esProc = {};
-  esProc.executable = esFile;
-  return esProc;
-}
-
-es_message_t MakeESMessage(es_event_type_t eventType, es_process_t *instigator,
-                           struct timespec ts) {
-  es_message_t esMsg = {};
-
-  esMsg.time = ts;
-  esMsg.event_type = eventType;
-  esMsg.process = instigator;
-
-  return esMsg;
-}
-
-CF_EXTERN_C_END
-
-@implementation ESMessage
-- (instancetype)init {
-  return [self initWithBlock:nil];
-}
-
-- (instancetype)initWithBlock:(ESMessageBuilderBlock)block {
-  NSParameterAssert(block);
-
-  self = [super init];
-  if (self) {
-    _pid = arc4random();
-    [self initBaseObjects];
-    block(self);
-    [self fillLinks];
-  }
-  return self;
-}
-
-- (void)initBaseObjects {
-  self.executable = static_cast<es_file_t *>(calloc(1, sizeof(es_file_t)));
-  self.process = static_cast<es_process_t *>(calloc(1, sizeof(es_process_t)));
-
-  self.process->ppid = self.pid;
-  self.process->original_ppid = self.pid;
-  self.process->group_id = static_cast<pid_t>(arc4random());
-  self.process->session_id = static_cast<pid_t>(arc4random());
-  self.process->codesigning_flags =
-    0x1 | 0x20000000;  // CS_VALID | CS_SIGNED -> See kern/cs_blobs.h
-  self.process->is_platform_binary = false;
-  self.process->is_es_client = false;
-
-  self.message = static_cast<es_message_t *>(calloc(1, sizeof(es_message_t)));
-  self.message->version = 4;
-  self.message->mach_time = DISPATCH_TIME_NOW;
-  self.message->deadline = DISPATCH_TIME_FOREVER;
-  self.message->seq_num = 1;
-}
-
-- (void)fillLinks {
-  if (self.binaryPath != nil) {
-    self.executable->path = MakeStringToken(self.binaryPath);
-  }
-
-  if (self.process->executable == NULL) {
-    self.process->executable = self.executable;
-  }
-  if (self.message->process == NULL) {
-    self.message->process = self.process;
-  }
-}
-
-- (void)dealloc {
-  free(self.process);
-  free(self.executable);
-  free(self.message);
-}
-@end
-
-@implementation ESResponse
-@end
-
-@interface MockESClient : NSObject
-@property NSMutableArray *_Nonnull subscriptions;
-@property es_handler_block_t handler;
-@end
-
-@implementation MockESClient
-
-- (instancetype)init {
-  self = [super init];
-  if (self) {
-    @synchronized(self) {
-      _subscriptions = [NSMutableArray arrayWithCapacity:ES_EVENT_TYPE_LAST];
-      for (size_t i = 0; i < ES_EVENT_TYPE_LAST; i++) {
-        [self.subscriptions addObject:@NO];
-      }
-    }
-  }
-  return self;
-};
-
-- (void)resetSubscriptions {
-  for (size_t i = 0; i < ES_EVENT_TYPE_LAST; i++) {
-    _subscriptions[i] = @NO;
-  }
-}
-
-- (void)triggerHandler:(es_message_t *_Nonnull)msg {
-  self.handler((__bridge es_client_t *_Nullable)self, msg);
-}
-
-- (void)dealloc {
-  @synchronized(self) {
-    [self.subscriptions removeAllObjects];
-  }
-}
-
-@end
-
-@interface MockEndpointSecurity ()
-@property NSMutableArray<MockESClient *> *clients;
-
-// Array of collections of ESCallback blocks
-// This should be of size ES_EVENT_TYPE_LAST, allowing for indexing by ES_EVENT_TYPE_xxx members.
-@property NSMutableArray<NSMutableArray<ESCallback> *> *responseCallbacks;
-@end
-
-@implementation MockEndpointSecurity
-- (instancetype)init {
-  self = [super init];
-  if (self) {
-    @synchronized(self) {
-      _clients = [NSMutableArray array];
-      _responseCallbacks = [NSMutableArray arrayWithCapacity:ES_EVENT_TYPE_LAST];
-      for (size_t i = 0; i < ES_EVENT_TYPE_LAST; i++) {
-        [self.responseCallbacks addObject:[NSMutableArray array]];
-      }
-      [self reset];
-    }
-  }
-  return self;
-};
-
-- (void)resetResponseCallbacks {
-  for (NSMutableArray *callback in self.responseCallbacks) {
-    if (callback != nil) {
-      [callback removeAllObjects];
-    }
-  }
-}
-
-- (void)reset {
-  @synchronized(self) {
-    [self.clients removeAllObjects];
-    [self resetResponseCallbacks];
-  }
-};
-
-- (void)newClient:(es_client_t *_Nullable *_Nonnull)client
-          handler:(es_handler_block_t __strong)handler {
-  // es_client_t is generally used as a pointer to an opaque struct (secretly a mach port).
-  // There is also a few nonnull initialization checks on it.
-  MockESClient *mockClient = [[MockESClient alloc] init];
-  *client = (__bridge es_client_t *)mockClient;
-  mockClient.handler = handler;
-  [self.clients addObject:mockClient];
-}
-
-- (BOOL)removeClient:(es_client_t *_Nonnull)client {
-  MockESClient *clientToRemove = [self findClient:client];
-
-  if (!clientToRemove) {
-    NSLog(@"Attempted to remove unknown mock es client.");
-    return NO;
-  }
-
-  [self.clients removeObject:clientToRemove];
-  return YES;
-}
-
-- (void)triggerHandler:(es_message_t *_Nonnull)msg {
-  for (MockESClient *client in self.clients) {
-    if (client.subscriptions[msg->event_type]) {
-      [client triggerHandler:msg];
-    }
-  }
-}
-
-- (void)registerResponseCallback:(es_event_type_t)t withCallback:(ESCallback _Nonnull)callback {
-  @synchronized(self) {
-    [self.responseCallbacks[t] addObject:callback];
-  }
-}
-
-- (es_respond_result_t)respond_auth_result:(const es_message_t *_Nonnull)msg
-                                    result:(es_auth_result_t)result
-                                     cache:(bool)cache {
-  @synchronized(self) {
-    ESResponse *response = [[ESResponse alloc] init];
-    response.result = result;
-    response.shouldCache = cache;
-    for (void (^callback)(ESResponse *) in self.responseCallbacks[msg->event_type]) {
-      callback(response);
-    }
-  }
-  return ES_RESPOND_RESULT_SUCCESS;
-};
-
-- (MockESClient *)findClient:(es_client_t *)client {
-  for (MockESClient *c in self.clients) {
-    // Since we're mocking out a C interface and using this exact pointer as our
-    // client identifier, only check for pointer equality.
-    if (client == (__bridge es_client_t *)c) {
-      return c;
-    }
-  }
-  return nil;
-}
-
-- (void)setSubscriptions:(const es_event_type_t *_Nonnull)events
-             event_count:(uint32_t)event_count
-                   value:(NSNumber *)value
-                  client:(es_client_t *)client {
-  @synchronized(self) {
-    MockESClient *toUpdate = [self findClient:client];
-
-    if (toUpdate == nil) {
-      NSLog(@"setting subscription for unknown client");
-      return;
-    }
-
-    for (size_t i = 0; i < event_count; i++) {
-      toUpdate.subscriptions[events[i]] = value;
-    }
-  }
-}
-
-+ (instancetype _Nonnull)mockEndpointSecurity {
-  static MockEndpointSecurity *sharedES;
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    sharedES = [[MockEndpointSecurity alloc] init];
-  });
-  return sharedES;
-};
-@end
-
-API_UNAVAILABLE(ios, tvos, watchos)
-es_message_t *_Nullable es_copy_message(const es_message_t *_Nonnull msg) {
-  return (es_message_t *)msg;
-};
-
-API_UNAVAILABLE(ios, tvos, watchos)
-void es_free_message(es_message_t *_Nonnull msg){};
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_new_client_result_t es_new_client(es_client_t *_Nullable *_Nonnull client,
-                                     es_handler_block_t _Nonnull handler) {
-  [[MockEndpointSecurity mockEndpointSecurity] newClient:client handler:handler];
-  return ES_NEW_CLIENT_RESULT_SUCCESS;
-};
-
-es_return_t es_mute_process(es_client_t * _Nonnull client,
-                            const audit_token_t * _Nonnull audit_token) {
-  return ES_RETURN_SUCCESS;
-}
-
-#if defined(MAC_OS_VERSION_12_0) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_12_0
-API_AVAILABLE(macos(12.0))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_muted_paths_events(es_client_t *_Nonnull client,
-                                  es_muted_paths_t *_Nonnull *_Nullable muted_paths) {
-  es_muted_paths_t *tmp = (es_muted_paths_t *)malloc(sizeof(es_muted_paths_t));
-
-  tmp->count = 0;
-  *muted_paths = (es_muted_paths_t *_Nullable)tmp;
-
-  return ES_RETURN_SUCCESS;
-};
-
-API_AVAILABLE(macos(12.0))
-API_UNAVAILABLE(ios, tvos, watchos)
-void es_release_muted_paths(es_muted_paths_t *_Nonnull muted_paths) {
-  free(muted_paths);
-}
-#endif
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos) es_return_t es_delete_client(es_client_t *_Nullable client) {
-  if (![[MockEndpointSecurity mockEndpointSecurity] removeClient:client]) {
-    return ES_RETURN_ERROR;
-  }
-  return ES_RETURN_SUCCESS;
-};
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_respond_result_t es_respond_auth_result(es_client_t *_Nonnull client,
-                                           const es_message_t *_Nonnull message,
-                                           es_auth_result_t result, bool cache) {
-  return [[MockEndpointSecurity mockEndpointSecurity] respond_auth_result:message
-                                                                   result:result
-                                                                    cache:cache];
-};
-
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_subscribe(es_client_t *_Nonnull client, const es_event_type_t *_Nonnull events,
-                         uint32_t event_count) {
-  [[MockEndpointSecurity mockEndpointSecurity] setSubscriptions:events
-                                                    event_count:event_count
-                                                          value:@YES
-                                                         client:client];
-  return ES_RETURN_SUCCESS;
-}
-API_AVAILABLE(macos(10.15))
-API_UNAVAILABLE(ios, tvos, watchos)
-es_return_t es_unsubscribe(es_client_t *_Nonnull client, const es_event_type_t *_Nonnull events,
-                           uint32_t event_count) {
-  [[MockEndpointSecurity mockEndpointSecurity] setSubscriptions:events
-                                                    event_count:event_count
-                                                          value:@NO
-                                                         client:client];
-
-  return ES_RETURN_SUCCESS;
-};

Source/santad/EventProviders/SNTCachingEndpointSecurityManager.mm

@@ -1,210 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import "Source/santad/EventProviders/SNTCachingEndpointSecurityManager.h"
-
-#import "Source/common/SNTLogging.h"
-#import "Source/common/SantaCache.h"
-
-#include <EndpointSecurity/EndpointSecurity.h>
-#include <bsm/libbsm.h>
-
-uint64_t GetCurrentUptime() {
-  return clock_gettime_nsec_np(CLOCK_MONOTONIC);
-}
-template <>
-uint64_t SantaCacheHasher<santa_vnode_id_t>(santa_vnode_id_t const &t) {
-  return (SantaCacheHasher<uint64_t>(t.fsid) << 1) ^ SantaCacheHasher<uint64_t>(t.fileid);
-}
-
-@implementation SNTCachingEndpointSecurityManager {
-  // Create 2 separate caches, mapping from the (filesysem + vnode ID) to a decision with a timestamp.
-  // The root cache is for decisions on the root volume, which can never be unmounted and the other
-  // is for executions from all other volumes. This cache will be emptied if any volume is unmounted.
-  SantaCache<santa_vnode_id_t, uint64_t> *_rootDecisionCache;
-  SantaCache<santa_vnode_id_t, uint64_t> *_nonRootDecisionCache;
-  uint64_t _rootVnodeID;
-}
-
-- (instancetype)init {
-  self = [super init];
-  if (self) {
-    _rootDecisionCache = new SantaCache<santa_vnode_id_t, uint64_t>();
-    _nonRootDecisionCache = new SantaCache<santa_vnode_id_t, uint64_t>();
-
-    // Store the filesystem ID of the root vnode for split-cache usage.
-    // If the stat fails for any reason _rootVnodeID will be 0 and all decisions will be in a single cache.
-    struct stat rootStat;
-    if (stat("/", &rootStat) == 0) {
-      _rootVnodeID = (uint64_t)rootStat.st_dev;
-    }
-  }
-
-  return self;
-}
-
-- (void)dealloc {
-  if (_rootDecisionCache) delete _rootDecisionCache;
-  if (_nonRootDecisionCache) delete _nonRootDecisionCache;
-}
-
-- (BOOL)respondFromCache:(es_message_t *)m API_AVAILABLE(macos(10.15)) {
-  auto vnode_id = [self vnodeIDForFile:m->event.exec.target->executable];
-  while (true) {
-    // Check to see if item is in cache
-    auto return_action = [self checkCache:vnode_id];
-
-    // If item was in cache with a valid response, return it.
-    // If item is in cache but hasn't received a response yet, sleep for a bit.
-    // If item is not in cache, break out of loop and forward request to callback.
-    if (RESPONSE_VALID(return_action)) {
-      switch (return_action) {
-        case ACTION_RESPOND_ALLOW:
-          es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, true);
-          break;
-        case ACTION_RESPOND_ALLOW_COMPILER: {
-          pid_t pid = audit_token_to_pid(m->process->audit_token);
-          [self setIsCompilerPID:pid];
-          // Don't let ES cache compilers
-          es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, false);
-          break;
-        }
-        default: es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, false); break;
-      }
-      return YES;
-    } else if (return_action == ACTION_REQUEST_BINARY || return_action == ACTION_RESPOND_ACK) {
-      // TODO(rah): Look at a replacement for msleep(), maybe NSCondition
-      usleep(5000);
-    } else {
-      break;
-    }
-  }
-
-  [self addToCache:vnode_id decision:ACTION_REQUEST_BINARY currentTicks:0];
-  return NO;
-}
-
-- (int)postAction:(santa_action_t)action
-       forMessage:(santa_message_t)sm API_AVAILABLE(macos(10.15)) {
-  es_respond_result_t ret;
-  switch (action) {
-    case ACTION_RESPOND_ALLOW_COMPILER:
-      [self setIsCompilerPID:sm.pid];
-
-      // Allow the exec and cache in our internal cache but don't let ES cache, because then
-      // we won't see future execs of the compiler in order to record the PID.
-      [self addToCache:sm.vnode_id
-              decision:ACTION_RESPOND_ALLOW_COMPILER
-          currentTicks:GetCurrentUptime()];
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_ALLOW,
-                                   false);
-      break;
-    case ACTION_RESPOND_ALLOW:
-    case ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE:
-      [self addToCache:sm.vnode_id decision:ACTION_RESPOND_ALLOW currentTicks:GetCurrentUptime()];
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_ALLOW,
-                                   true);
-      break;
-    case ACTION_RESPOND_DENY:
-      [self addToCache:sm.vnode_id decision:ACTION_RESPOND_DENY currentTicks:GetCurrentUptime()];
-      OS_FALLTHROUGH;
-    case ACTION_RESPOND_TOOLONG:
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_DENY,
-                                   false);
-      break;
-    case ACTION_RESPOND_ACK: return ES_RESPOND_RESULT_SUCCESS;
-    default: ret = ES_RESPOND_RESULT_ERR_INVALID_ARGUMENT;
-  }
-
-  return ret;
-}
-
-- (void)addToCache:(santa_vnode_id_t)identifier
-          decision:(santa_action_t)decision
-      currentTicks:(uint64_t)microsecs {
-  auto _decisionCache = [self cacheForVnodeID:identifier];
-  switch (decision) {
-    case ACTION_REQUEST_BINARY:
-      _decisionCache->set(identifier, (uint64_t)ACTION_REQUEST_BINARY << 56, 0);
-      break;
-    case ACTION_RESPOND_ACK:
-      _decisionCache->set(identifier, (uint64_t)ACTION_RESPOND_ACK << 56,
-                          ((uint64_t)ACTION_REQUEST_BINARY << 56));
-      break;
-    case ACTION_RESPOND_ALLOW:
-    case ACTION_RESPOND_ALLOW_COMPILER:
-    case ACTION_RESPOND_DENY: {
-      // Decision is stored in upper 8 bits, timestamp in remaining 56.
-      uint64_t val = ((uint64_t)decision << 56) | (microsecs & 0xFFFFFFFFFFFFFF);
-      if (!_decisionCache->set(identifier, val, ((uint64_t)ACTION_REQUEST_BINARY << 56))) {
-        _decisionCache->set(identifier, val, ((uint64_t)ACTION_RESPOND_ACK << 56));
-      }
-      break;
-    }
-    case ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE: {
-      // Decision is stored in upper 8 bits, timestamp in remaining 56.
-      uint64_t val = ((uint64_t)decision << 56) | (microsecs & 0xFFFFFFFFFFFFFF);
-      _decisionCache->set(identifier, val, 0);
-      break;
-    }
-    default: break;
-  }
-  // TODO(rah): Look at a replacement for wakeup(), maybe NSCondition
-}
-
-- (BOOL)flushCacheNonRootOnly:(BOOL)nonRootOnly API_AVAILABLE(macos(10.15)) {
-  _nonRootDecisionCache->clear();
-  if (!nonRootOnly) _rootDecisionCache->clear();
-  if (!self.connectionEstablished) return YES;  // if not connected, there's nothing to flush.
-  return es_clear_cache(self.client) == ES_CLEAR_CACHE_RESULT_SUCCESS;
-}
-
-- (NSArray<NSNumber *> *)cacheCounts {
-  return @[ @(_rootDecisionCache->count()), @(_nonRootDecisionCache->count()) ];
-}
-
-- (santa_action_t)checkCache:(santa_vnode_id_t)vnodeID {
-  auto result = ACTION_UNSET;
-  uint64_t decision_time = 0;
-
-  uint64_t cache_val = [self cacheForVnodeID:vnodeID]->get(vnodeID);
-  if (cache_val == 0) return result;
-
-  // Decision is stored in upper 8 bits, timestamp in remaining 56.
-  result = (santa_action_t)(cache_val >> 56);
-  decision_time = (cache_val & ~(0xFF00000000000000));
-
-  if (RESPONSE_VALID(result)) {
-    if (result == ACTION_RESPOND_DENY) {
-      auto expiry_time = decision_time + (500 * 100000);  // kMaxCacheDenyTimeMilliseconds
-      if (expiry_time < GetCurrentUptime()) {
-        [self cacheForVnodeID:vnodeID]->remove(vnodeID);
-        return ACTION_UNSET;
-      }
-    }
-  }
-  return result;
-}
-
-- (kern_return_t)removeCacheEntryForVnodeID:(santa_vnode_id_t)vnodeID {
-  [self cacheForVnodeID:vnodeID]->remove(vnodeID);
-  // TODO(rah): Look at a replacement for wakeup(), maybe NSCondition
-  return 0;
-}
-
-- (SantaCache<santa_vnode_id_t, uint64_t> *)cacheForVnodeID:(santa_vnode_id_t)vnodeID {
-  return (vnodeID.fsid == _rootVnodeID || _rootVnodeID == 0) ? _rootDecisionCache : _nonRootDecisionCache;
-}
-
-@end

Source/santad/EventProviders/SNTDeviceManagerTest.mm

@@ -1,291 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-#import <DiskArbitration/DiskArbitration.h>
-#import <OCMock/OCMock.h>
-#import <XCTest/XCTest.h>
-#import <bsm/libbsm.h>
-
-#include <sys/mount.h>
-
-#import "Source/common/SNTConfigurator.h"
-#import "Source/common/SNTDeviceEvent.h"
-#import "Source/santad/EventProviders/SNTDeviceManager.h"
-
-#import "Source/santad/EventProviders/DiskArbitrationTestUtil.h"
-#import "Source/santad/EventProviders/EndpointSecurityTestUtil.h"
-
-@interface SNTDeviceManagerTest : XCTestCase
-@property id mockConfigurator;
-@end
-
-@implementation SNTDeviceManagerTest
-
-- (void)setUp {
-  [super setUp];
-  self.mockConfigurator = OCMClassMock([SNTConfigurator class]);
-  OCMStub([self.mockConfigurator configurator]).andReturn(self.mockConfigurator);
-  OCMStub([self.mockConfigurator eventLogType]).andReturn(-1);
-
-  fclose(stdout);
-}
-
-- (ESResponse *)triggerTestMountEvent:(SNTDeviceManager *)deviceManager
-                               mockES:(MockEndpointSecurity *)mockES
-                               mockDA:(MockDiskArbitration *)mockDA
-                            eventType:(es_event_type_t)eventType
-                    diskInfoOverrides:(NSDictionary *)diskInfo {
-  if (!deviceManager.subscribed) {
-    // [deviceManager listen] is synchronous, but we want to asynchronously dispatch it
-    // with an enforced timeout to ensure that we never run into issues where the client
-    // never instantiates.
-    XCTestExpectation *initExpectation =
-      [self expectationWithDescription:@"Wait for SNTDeviceManager to instantiate"];
-
-    dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0), ^{
-      [deviceManager listen];
-    });
-
-    dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0), ^{
-      while (!deviceManager.subscribed)
-        ;
-      [initExpectation fulfill];
-    });
-    [self waitForExpectations:@[ initExpectation ] timeout:60.0];
-  }
-
-  struct statfs *fs = static_cast<struct statfs *>(calloc(1, sizeof(struct statfs)));
-  NSString *test_mntfromname = @"/dev/disk2s1";
-  NSString *test_mntonname = @"/Volumes/KATE'S 4G";
-  const char *c_mntfromname = [test_mntfromname UTF8String];
-  const char *c_mntonname = [test_mntonname UTF8String];
-
-  strncpy(fs->f_mntfromname, c_mntfromname, MAXPATHLEN);
-  strncpy(fs->f_mntonname, c_mntonname, MAXPATHLEN);
-
-  MockDADisk *disk = [[MockDADisk alloc] init];
-  disk.diskDescription = @{
-    (__bridge NSString *)kDADiskDescriptionDeviceProtocolKey : @"USB",
-    (__bridge NSString *)kDADiskDescriptionMediaRemovableKey : @YES,
-    @"DAVolumeMountable" : @YES,
-    @"DAVolumePath" : test_mntonname,
-    @"DADeviceModel" : @"Some device model",
-    @"DADevicePath" : test_mntonname,
-    @"DADeviceVendor" : @"Some vendor",
-    @"DAAppearanceTime" : @0,
-    @"DAMediaBSDName" : test_mntfromname,
-  };
-
-  if (diskInfo != nil) {
-    NSMutableDictionary *mergedDiskDescription = [disk.diskDescription mutableCopy];
-    for (NSString *key in diskInfo) {
-      mergedDiskDescription[key] = diskInfo[key];
-    }
-    disk.diskDescription = (NSDictionary *)mergedDiskDescription;
-  }
-
-  [mockDA insert:disk bsdName:test_mntfromname];
-
-  ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-    m.binaryPath = @"/System/Library/Filesystems/msdos.fs/Contents/Resources/mount_msdos";
-    m.message->action_type = ES_ACTION_TYPE_AUTH;
-    m.message->event_type = eventType;
-    if (eventType == ES_EVENT_TYPE_AUTH_MOUNT) {
-      m.message->event = (es_events_t){.mount = {.statfs = fs}};
-    } else {
-      m.message->event = (es_events_t){.remount = {.statfs = fs}};
-    }
-  }];
-
-  XCTestExpectation *mountExpectation =
-    [self expectationWithDescription:@"Wait for response from ES"];
-  __block ESResponse *got;
-  [mockES registerResponseCallback:eventType
-                      withCallback:^(ESResponse *r) {
-                        got = r;
-                        [mountExpectation fulfill];
-                      }];
-
-  [mockES triggerHandler:m.message];
-
-  [self waitForExpectations:@[ mountExpectation ] timeout:60.0];
-  free(fs);
-
-  return got;
-}
-
-- (void)testUSBBlockDisabled {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-
-  MockDiskArbitration *mockDA = [MockDiskArbitration mockDiskArbitration];
-  [mockDA reset];
-
-  SNTDeviceManager *deviceManager = [[SNTDeviceManager alloc] init];
-  deviceManager.blockUSBMount = NO;
-  ESResponse *got = [self triggerTestMountEvent:deviceManager
-                                         mockES:mockES
-                                         mockDA:mockDA
-                                      eventType:ES_EVENT_TYPE_AUTH_MOUNT
-                              diskInfoOverrides:nil];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_ALLOW);
-}
-
-- (void)testRemount {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-
-  MockDiskArbitration *mockDA = [MockDiskArbitration mockDiskArbitration];
-  [mockDA reset];
-
-  SNTDeviceManager *deviceManager = [[SNTDeviceManager alloc] init];
-  deviceManager.blockUSBMount = YES;
-  deviceManager.remountArgs = @[ @"noexec", @"rdonly" ];
-
-  XCTestExpectation *expectation =
-    [self expectationWithDescription:@"Wait for SNTDeviceManager's blockCallback to trigger"];
-
-  __block NSString *gotmntonname, *gotmntfromname;
-  __block NSArray<NSString *> *gotRemountedArgs;
-  deviceManager.deviceBlockCallback = ^(SNTDeviceEvent *event) {
-    gotRemountedArgs = event.remountArgs;
-    gotmntonname = event.mntonname;
-    gotmntfromname = event.mntfromname;
-    [expectation fulfill];
-  };
-
-  ESResponse *got = [self triggerTestMountEvent:deviceManager
-                                         mockES:mockES
-                                         mockDA:mockDA
-                                      eventType:ES_EVENT_TYPE_AUTH_MOUNT
-                              diskInfoOverrides:nil];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_DENY);
-  XCTAssertEqual(mockDA.wasRemounted, YES);
-
-  [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-  XCTAssertEqualObjects(gotRemountedArgs, deviceManager.remountArgs);
-  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
-  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
-}
-
-- (void)testBlockNoRemount {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-
-  MockDiskArbitration *mockDA = [MockDiskArbitration mockDiskArbitration];
-  [mockDA reset];
-
-  SNTDeviceManager *deviceManager = [[SNTDeviceManager alloc] init];
-  deviceManager.blockUSBMount = YES;
-
-  XCTestExpectation *expectation =
-    [self expectationWithDescription:@"Wait for SNTDeviceManager's blockCallback to trigger"];
-
-  __block NSString *gotmntonname, *gotmntfromname;
-  __block NSArray<NSString *> *gotRemountedArgs;
-  deviceManager.deviceBlockCallback = ^(SNTDeviceEvent *event) {
-    gotRemountedArgs = event.remountArgs;
-    gotmntonname = event.mntonname;
-    gotmntfromname = event.mntfromname;
-    [expectation fulfill];
-  };
-
-  ESResponse *got = [self triggerTestMountEvent:deviceManager
-                                         mockES:mockES
-                                         mockDA:mockDA
-                                      eventType:ES_EVENT_TYPE_AUTH_MOUNT
-                              diskInfoOverrides:nil];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_DENY);
-
-  [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-  XCTAssertNil(gotRemountedArgs);
-  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
-  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
-}
-
-- (void)testEnsureRemountsCannotChangePerms {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-
-  MockDiskArbitration *mockDA = [MockDiskArbitration mockDiskArbitration];
-  [mockDA reset];
-
-  SNTDeviceManager *deviceManager = [[SNTDeviceManager alloc] init];
-  deviceManager.blockUSBMount = YES;
-  deviceManager.remountArgs = @[ @"noexec", @"rdonly" ];
-
-  XCTestExpectation *expectation =
-    [self expectationWithDescription:@"Wait for SNTDeviceManager's blockCallback to trigger"];
-
-  __block NSString *gotmntonname, *gotmntfromname;
-  __block NSArray<NSString *> *gotRemountedArgs;
-  deviceManager.deviceBlockCallback = ^(SNTDeviceEvent *event) {
-    gotRemountedArgs = event.remountArgs;
-    gotmntonname = event.mntonname;
-    gotmntfromname = event.mntfromname;
-    [expectation fulfill];
-  };
-
-  ESResponse *got = [self triggerTestMountEvent:deviceManager
-                                         mockES:mockES
-                                         mockDA:mockDA
-                                      eventType:ES_EVENT_TYPE_AUTH_REMOUNT
-                              diskInfoOverrides:nil];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_DENY);
-  XCTAssertEqual(mockDA.wasRemounted, YES);
-
-  [self waitForExpectations:@[ expectation ] timeout:10.0];
-
-  XCTAssertEqualObjects(gotRemountedArgs, deviceManager.remountArgs);
-  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
-  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
-}
-
-- (void)testEnsureDMGsDoNotPrompt {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-
-  MockDiskArbitration *mockDA = [MockDiskArbitration mockDiskArbitration];
-  [mockDA reset];
-
-  SNTDeviceManager *deviceManager = [[SNTDeviceManager alloc] init];
-  deviceManager.blockUSBMount = YES;
-  deviceManager.remountArgs = @[ @"noexec", @"rdonly" ];
-
-  deviceManager.deviceBlockCallback = ^(SNTDeviceEvent *event) {
-    XCTFail(@"Should not be called");
-  };
-
-  NSDictionary *diskInfo = @{
-    (__bridge NSString *)kDADiskDescriptionDeviceProtocolKey: @"Virtual Interface",
-    (__bridge NSString *)kDADiskDescriptionDeviceModelKey: @"Disk Image",
-    (__bridge NSString *)kDADiskDescriptionMediaNameKey: @"disk image",
-  };
-
-
-  ESResponse *got = [self triggerTestMountEvent:deviceManager
-                                         mockES:mockES
-                                         mockDA:mockDA
-                                      eventType:ES_EVENT_TYPE_AUTH_MOUNT
-                              diskInfoOverrides:diskInfo];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_ALLOW);
-  XCTAssertEqual(mockDA.wasRemounted, NO);
-}
-@end

Source/santad/EventProviders/SNTEndpointSecurityAuthorizer.h

@@ -0,0 +1,38 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+
+#import "Source/santad/EventProviders/AuthResultCache.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityEventHandler.h"
+#import "Source/santad/SNTCompilerController.h"
+#import "Source/santad/SNTExecutionController.h"
+
+/// ES Client focused on subscribing to AUTH variants and authorizing the events
+/// based on configured policy.
+@interface SNTEndpointSecurityAuthorizer
+    : SNTEndpointSecurityClient <SNTEndpointSecurityEventHandler>
+
+- (instancetype)
+       initWithESAPI:
+         (std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI>)
+           esApi
+      execController:(SNTExecutionController *)execController
+  compilerController:(SNTCompilerController *)compilerController
+     authResultCache:
+       (std::shared_ptr<santa::santad::event_providers::AuthResultCache>)authResultCache;
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityAuthorizer.mm

@@ -0,0 +1,145 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/santad/EventProviders/SNTEndpointSecurityAuthorizer.h"
+
+#include <EndpointSecurity/ESTypes.h>
+#include <os/base.h>
+#include <stdlib.h>
+
+#import "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::Message;
+
+@interface SNTEndpointSecurityAuthorizer ()
+@property SNTCompilerController *compilerController;
+@property SNTExecutionController *execController;
+@end
+
+@implementation SNTEndpointSecurityAuthorizer {
+  std::shared_ptr<AuthResultCache> _authResultCache;
+}
+
+- (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi
+               execController:(SNTExecutionController *)execController
+           compilerController:(SNTCompilerController *)compilerController
+              authResultCache:(std::shared_ptr<AuthResultCache>)authResultCache {
+  self = [super initWithESAPI:std::move(esApi)];
+  if (self) {
+    _execController = execController;
+    _compilerController = compilerController;
+    _authResultCache = authResultCache;
+
+    [self establishClientOrDie];
+  }
+  return self;
+}
+
+- (void)processMessage:(const Message &)msg {
+  const es_file_t *targetFile = msg->event.exec.target->executable;
+
+  while (true) {
+    santa_action_t returnAction = self->_authResultCache->CheckCache(targetFile);
+    if (RESPONSE_VALID(returnAction)) {
+      es_auth_result_t authResult = ES_AUTH_RESULT_DENY;
+
+      switch (returnAction) {
+        case ACTION_RESPOND_ALLOW_COMPILER:
+          [self.compilerController setProcess:msg->event.exec.target->audit_token isCompiler:true];
+          OS_FALLTHROUGH;
+        case ACTION_RESPOND_ALLOW: authResult = ES_AUTH_RESULT_ALLOW; break;
+        default: break;
+      }
+
+      [self respondToMessage:msg
+              withAuthResult:authResult
+                   cacheable:(authResult == ES_AUTH_RESULT_ALLOW)];
+      return;
+    } else if (returnAction == ACTION_REQUEST_BINARY) {
+      // TODO(mlw): Add a metric here to observe how ofthen this happens in practice.
+      // TODO(mlw): Look into caching a `Deferred<value>` to better prevent
+      // raciness of multiple threads checking the cache simultaneously.
+      // Also mitigates need to poll.
+      usleep(5000);
+    } else {
+      break;
+    }
+  }
+
+  self->_authResultCache->AddToCache(targetFile, ACTION_REQUEST_BINARY);
+
+  [self.execController validateExecEvent:msg
+                              postAction:^bool(santa_action_t action) {
+                                return [self postAction:action forMessage:msg];
+                              }];
+}
+
+- (void)handleMessage:(Message &&)esMsg {
+  if (unlikely(esMsg->event_type != ES_EVENT_TYPE_AUTH_EXEC)) {
+    // This is a programming error
+    LOGE(@"Atteempting to authorize a non-exec event");
+    [NSException raise:@"Invalid event type"
+                format:@"Authorizing unexpected event type: %d", esMsg->event_type];
+  }
+
+  if (![self.execController synchronousShouldProcessExecEvent:esMsg]) {
+    [self postAction:ACTION_RESPOND_DENY forMessage:esMsg];
+    return;
+  }
+
+  [self processMessage:std::move(esMsg)
+               handler:^(const Message &msg) {
+                 [self processMessage:msg];
+               }];
+}
+
+- (bool)postAction:(santa_action_t)action forMessage:(const Message &)esMsg {
+  es_auth_result_t authResult;
+
+  switch (action) {
+    case ACTION_RESPOND_ALLOW_COMPILER:
+      [self.compilerController setProcess:esMsg->event.exec.target->audit_token isCompiler:true];
+      OS_FALLTHROUGH;
+    case ACTION_RESPOND_ALLOW: authResult = ES_AUTH_RESULT_ALLOW; break;
+    case ACTION_RESPOND_DENY: authResult = ES_AUTH_RESULT_DENY; break;
+    default:
+      // This is a programming error. Bail.
+      LOGE(@"Invalid action for postAction, exiting.");
+      [NSException raise:@"Invalid post action" format:@"Invalid post action: %d", action];
+  }
+
+  self->_authResultCache->AddToCache(esMsg->event.exec.target->executable, action);
+
+  // Don't let the ES framework cache DENY results. Santa only flushes ES cache
+  // when a new DENY rule is received. If DENY results were cached and a rule
+  // update made the executable allowable, ES would continue to apply the DENY
+  // cached result. Note however that the local AuthResultCache will cache
+  // DENY results.
+  return [self respondToMessage:esMsg
+                 withAuthResult:authResult
+                      cacheable:(authResult == ES_AUTH_RESULT_ALLOW)];
+}
+
+- (void)enable {
+  [super subscribeAndClearCache:{
+                                  ES_EVENT_TYPE_AUTH_EXEC,
+                                }];
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityAuthorizerTest.mm

@@ -0,0 +1,273 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/ESTypes.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <map>
+#include <memory>
+#include <set>
+
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityAuthorizer.h"
+#import "Source/santad/SNTCompilerController.h"
+#import "Source/santad/SNTExecutionController.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::endpoint_security::Message;
+
+class MockAuthResultCache : public AuthResultCache {
+ public:
+  using AuthResultCache::AuthResultCache;
+
+  MOCK_METHOD(bool, AddToCache, (const es_file_t *es_file, santa_action_t decision));
+  MOCK_METHOD(santa_action_t, CheckCache, (const es_file_t *es_file));
+};
+
+@interface SNTEndpointSecurityAuthorizer (Testing)
+- (void)processMessage:(const Message &)msg;
+- (bool)postAction:(santa_action_t)action forMessage:(const Message &)esMsg;
+@end
+
+@interface SNTEndpointSecurityAuthorizerTest : XCTestCase
+@property id mockExecController;
+@end
+
+@implementation SNTEndpointSecurityAuthorizerTest
+
+- (void)setUp {
+  self.mockExecController = OCMStrictClassMock([SNTExecutionController class]);
+}
+
+- (void)tearDown {
+  [self.mockExecController stopMocking];
+}
+
+- (void)testEnable {
+  // Ensure the client subscribes to expected event types
+  std::set<es_event_type_t> expectedEventSubs{ES_EVENT_TYPE_AUTH_EXEC};
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  id authClient = [[SNTEndpointSecurityAuthorizer alloc] initWithESAPI:mockESApi];
+
+  EXPECT_CALL(*mockESApi, ClearCache)
+    .After(EXPECT_CALL(*mockESApi, Subscribe(testing::_, expectedEventSubs))
+             .WillOnce(testing::Return(true)))
+    .WillOnce(testing::Return(true));
+
+  [authClient enable];
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testHandleMessage {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_EXEC, &proc, ActionType::Auth);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  SNTEndpointSecurityAuthorizer *authClient =
+    [[SNTEndpointSecurityAuthorizer alloc] initWithESAPI:mockESApi
+                                          execController:self.mockExecController
+                                      compilerController:nil
+                                         authResultCache:nullptr];
+
+  id mockAuthClient = OCMPartialMock(authClient);
+
+  // Test unhandled event type
+  {
+    // Temporarily change the event type
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_EXEC;
+    XCTAssertThrows([authClient handleMessage:Message(mockESApi, &esMsg)]);
+    esMsg.event_type = ES_EVENT_TYPE_AUTH_EXEC;
+  }
+
+  // Test SNTExecutionController determines the event shouldn't be processed
+  {
+    Message msg(mockESApi, &esMsg);
+
+    OCMExpect([self.mockExecController synchronousShouldProcessExecEvent:msg])
+      .ignoringNonObjectArgs()
+      .andReturn(NO);
+
+    OCMExpect([mockAuthClient postAction:ACTION_RESPOND_DENY forMessage:Message(mockESApi, &esMsg)])
+      .ignoringNonObjectArgs();
+    OCMStub([mockAuthClient postAction:ACTION_RESPOND_DENY forMessage:Message(mockESApi, &esMsg)])
+      .ignoringNonObjectArgs()
+      .andDo(nil);
+
+    [mockAuthClient handleMessage:std::move(msg)];
+    XCTAssertTrue(OCMVerifyAll(mockAuthClient));
+  }
+
+  // Test SNTExecutionController determines the event should be processed and
+  // processMessage:handler: is called.
+  {
+    Message msg(mockESApi, &esMsg);
+
+    OCMExpect([self.mockExecController synchronousShouldProcessExecEvent:msg])
+      .ignoringNonObjectArgs()
+      .andReturn(YES);
+
+    OCMExpect([mockAuthClient processMessage:Message(mockESApi, &esMsg) handler:[OCMArg any]])
+      .ignoringNonObjectArgs();
+    OCMStub([mockAuthClient processMessage:Message(mockESApi, &esMsg) handler:[OCMArg any]])
+      .ignoringNonObjectArgs()
+      .andDo(nil);
+
+    [mockAuthClient handleMessage:std::move(msg)];
+    XCTAssertTrue(OCMVerifyAll(mockAuthClient));
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+
+  [mockAuthClient stopMocking];
+}
+
+- (void)testProcessMessageWaitThenAllow {
+  // This test ensures that if there is an outstanding action for
+  // an item, it will check the cache again until a result exists.
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_file_t execFile = MakeESFile("bar");
+  es_process_t execProc = MakeESProcess(&execFile, MakeAuditToken(12, 23), MakeAuditToken(34, 45));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_EXEC, &proc, ActionType::Auth);
+  esMsg.event.exec.target = &execProc;
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  auto mockAuthCache = std::make_shared<MockAuthResultCache>(nullptr);
+  EXPECT_CALL(*mockAuthCache, CheckCache)
+    .WillOnce(testing::Return(ACTION_REQUEST_BINARY))
+    .WillOnce(testing::Return(ACTION_REQUEST_BINARY))
+    .WillOnce(testing::Return(ACTION_RESPOND_ALLOW_COMPILER))
+    .WillOnce(testing::Return(ACTION_UNSET));
+  EXPECT_CALL(*mockAuthCache, AddToCache(testing::_, ACTION_REQUEST_BINARY))
+    .WillOnce(testing::Return(true));
+
+  id mockCompilerController = OCMStrictClassMock([SNTCompilerController class]);
+  OCMExpect([mockCompilerController setProcess:execProc.audit_token isCompiler:true]);
+
+  SNTEndpointSecurityAuthorizer *authClient =
+    [[SNTEndpointSecurityAuthorizer alloc] initWithESAPI:mockESApi
+                                          execController:self.mockExecController
+                                      compilerController:mockCompilerController
+                                         authResultCache:mockAuthCache];
+  id mockAuthClient = OCMPartialMock(authClient);
+
+  // This block tests that processing is held up until an outstanding thread
+  // processing another event completes and returns a result. This test
+  // specifically will check the `ACTION_RESPOND_ALLOW_COMPILER` flow.
+  {
+    Message msg(mockESApi, &esMsg);
+    OCMExpect([mockAuthClient respondToMessage:msg
+                                withAuthResult:ES_AUTH_RESULT_ALLOW
+                                     cacheable:true]);
+
+    [mockAuthClient processMessage:msg];
+
+    XCTAssertTrue(OCMVerifyAll(mockAuthClient));
+    XCTAssertTrue(OCMVerifyAll(mockCompilerController));
+  }
+
+  // This block tests uncached events storing appropriate cache marker and then
+  // running the exec controller to validate the exec event.
+  {
+    Message msg(mockESApi, &esMsg);
+    OCMExpect([self.mockExecController validateExecEvent:msg postAction:OCMOCK_ANY])
+      .ignoringNonObjectArgs();
+
+    [mockAuthClient processMessage:msg];
+
+    XCTAssertTrue(OCMVerifyAll(mockAuthClient));
+    XCTAssertTrue(OCMVerifyAll(mockCompilerController));
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockAuthCache.get());
+
+  [mockCompilerController stopMocking];
+  [mockAuthClient stopMocking];
+}
+
+- (void)testPostAction {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_file_t execFile = MakeESFile("bar");
+  es_process_t execProc = MakeESProcess(&execFile, MakeAuditToken(12, 23), MakeAuditToken(34, 45));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_EXEC, &proc, ActionType::Auth);
+  esMsg.event.exec.target = &execProc;
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  auto mockAuthCache = std::make_shared<MockAuthResultCache>(nullptr);
+  EXPECT_CALL(*mockAuthCache, AddToCache(&execFile, ACTION_RESPOND_ALLOW_COMPILER))
+    .WillOnce(testing::Return(true));
+  EXPECT_CALL(*mockAuthCache, AddToCache(&execFile, ACTION_RESPOND_ALLOW))
+    .WillOnce(testing::Return(true));
+  EXPECT_CALL(*mockAuthCache, AddToCache(&execFile, ACTION_RESPOND_DENY))
+    .WillOnce(testing::Return(true));
+
+  id mockCompilerController = OCMStrictClassMock([SNTCompilerController class]);
+  OCMExpect([mockCompilerController setProcess:execProc.audit_token isCompiler:true]);
+
+  SNTEndpointSecurityAuthorizer *authClient =
+    [[SNTEndpointSecurityAuthorizer alloc] initWithESAPI:mockESApi
+                                          execController:self.mockExecController
+                                      compilerController:mockCompilerController
+                                         authResultCache:mockAuthCache];
+  id mockAuthClient = OCMPartialMock(authClient);
+
+  {
+    Message msg(mockESApi, &esMsg);
+
+    XCTAssertThrows([mockAuthClient postAction:(santa_action_t)123 forMessage:msg]);
+
+    std::map<santa_action_t, es_auth_result_t> actions = {
+      {ACTION_RESPOND_ALLOW_COMPILER, ES_AUTH_RESULT_ALLOW},
+      {ACTION_RESPOND_ALLOW, ES_AUTH_RESULT_ALLOW},
+      {ACTION_RESPOND_DENY, ES_AUTH_RESULT_DENY},
+    };
+
+    for (const auto &kv : actions) {
+      OCMExpect([mockAuthClient respondToMessage:msg
+                                  withAuthResult:kv.second
+                                       cacheable:kv.second == ES_AUTH_RESULT_ALLOW]);
+
+      [mockAuthClient postAction:kv.first forMessage:msg];
+    }
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockAuthCache.get());
+
+  [mockCompilerController stopMocking];
+  [mockAuthClient stopMocking];
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityClient.h

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,17 +12,9 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#import <Foundation/Foundation.h>
-
-#import "Source/common/Santa.pbobjc.h"
-
-NS_ASSUME_NONNULL_BEGIN
-
-@protocol SNTLogOutput<NSObject>
-
-- (void)logEvent:(SNTPBSantaMessage *)event;
-- (void)flush;
+#include "Source/santad/EventProviders/SNTEndpointSecurityClientBase.h"
 
+/// This should be treated as an Abstract Base Class and not directly instantiated
+@interface SNTEndpointSecurityClient : NSObject <SNTEndpointSecurityClientBase>
+- (instancetype)init NS_UNAVAILABLE;
 @end
-
-NS_ASSUME_NONNULL_END

Source/santad/EventProviders/SNTEndpointSecurityClient.mm

@@ -0,0 +1,243 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+#include <EndpointSecurity/ESTypes.h>
+
+#include <bsm/libbsm.h>
+#include <dispatch/dispatch.h>
+#include <mach/mach_time.h>
+#include <stdlib.h>
+#include <sys/qos.h>
+
+#import "Source/common/SNTCommon.h"
+#import "Source/common/SNTConfigurator.h"
+#import "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::Message;
+
+@interface SNTEndpointSecurityClient ()
+@property int64_t deadlineMarginMS;
+@end
+;
+
+@implementation SNTEndpointSecurityClient {
+  std::shared_ptr<EndpointSecurityAPI> _esApi;
+  Client _esClient;
+  mach_timebase_info_data_t _timebase;
+  dispatch_queue_t _authQueue;
+  dispatch_queue_t _notifyQueue;
+}
+
+- (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi {
+  self = [super init];
+  if (self) {
+    _esApi = std::move(esApi);
+    _deadlineMarginMS = 5000;
+
+    if (mach_timebase_info(&_timebase) != KERN_SUCCESS) {
+      LOGE(@"Failed to get mach timebase info");
+      // Assumed to be transitory failure. Let the daemon restart.
+      exit(EXIT_FAILURE);
+    }
+
+    _authQueue = dispatch_queue_create(
+      "com.google.santa.daemon.auth_queue",
+      dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_CONCURRENT_WITH_AUTORELEASE_POOL,
+                                              QOS_CLASS_USER_INTERACTIVE, 0));
+
+    _notifyQueue = dispatch_queue_create(
+      "com.google.santa.daemon.notify_queue",
+      dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_CONCURRENT_WITH_AUTORELEASE_POOL,
+                                              QOS_CLASS_BACKGROUND, 0));
+  }
+  return self;
+}
+
+- (NSString *)errorMessageForNewClientResult:(es_new_client_result_t)result {
+  switch (result) {
+    case ES_NEW_CLIENT_RESULT_SUCCESS: return nil;
+    case ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED: return @"Full-disk access not granted";
+    case ES_NEW_CLIENT_RESULT_ERR_NOT_ENTITLED: return @"Not entitled";
+    case ES_NEW_CLIENT_RESULT_ERR_NOT_PRIVILEGED: return @"Not running as root";
+    case ES_NEW_CLIENT_RESULT_ERR_INVALID_ARGUMENT: return @"Invalid argument";
+    case ES_NEW_CLIENT_RESULT_ERR_INTERNAL: return @"Internal error";
+    case ES_NEW_CLIENT_RESULT_ERR_TOO_MANY_CLIENTS: return @"Too many simultaneous clients";
+    default: return @"Unknown error";
+  }
+}
+
+- (void)handleMessage:(Message &&)esMsg {
+  // This method should only be used by classes derived
+  // from SNTEndpointSecurityClient.
+  [self doesNotRecognizeSelector:_cmd];
+}
+
+- (BOOL)shouldHandleMessage:(const Message &)esMsg
+     ignoringOtherESClients:(BOOL)ignoringOtherESClients {
+  if (esMsg->process->is_es_client && ignoringOtherESClients) {
+    if (esMsg->action_type == ES_ACTION_TYPE_AUTH) {
+      [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_ALLOW cacheable:true];
+    }
+    return NO;
+  }
+
+  return YES;
+}
+
+- (void)establishClientOrDie {
+  if (self->_esClient.IsConnected()) {
+    // This is a programming error
+    LOGE(@"Client already established. Aborting.");
+    [NSException raise:@"Client already established" format:@"IsConnected already true"];
+  }
+
+  self->_esClient = self->_esApi->NewClient(^(es_client_t *c, Message esMsg) {
+    if ([self shouldHandleMessage:esMsg
+           ignoringOtherESClients:[[SNTConfigurator configurator]
+                                    ignoreOtherEndpointSecurityClients]]) {
+      [self handleMessage:std::move(esMsg)];
+    }
+  });
+
+  if (!self->_esClient.IsConnected()) {
+    NSString *errMsg = [self errorMessageForNewClientResult:_esClient.NewClientResult()];
+    LOGE(@"Unable to create EndpointSecurity client: %@", errMsg);
+    [NSException raise:@"Failed to create ES client" format:@"%@", errMsg];
+  } else {
+    LOGI(@"Connected to EndpointSecurity");
+  }
+
+  if (![self muteSelf]) {
+    [NSException raise:@"ES Mute Failure" format:@"Failed to mute self"];
+  }
+}
+
++ (bool)populateAuditTokenSelf:(audit_token_t *)tok {
+  mach_msg_type_number_t count = TASK_AUDIT_TOKEN_COUNT;
+  if (task_info(mach_task_self(), TASK_AUDIT_TOKEN, (task_info_t)tok, &count) != KERN_SUCCESS) {
+    LOGE(@"Failed to fetch this client's audit token.");
+    return false;
+  }
+
+  return true;
+}
+
+- (bool)muteSelf {
+  audit_token_t myAuditToken;
+  if (![SNTEndpointSecurityClient populateAuditTokenSelf:&myAuditToken]) {
+    return false;
+  }
+
+  if (!self->_esApi->MuteProcess(self->_esClient, &myAuditToken)) {
+    LOGE(@"Failed to mute this client's process.");
+    return false;
+  }
+
+  return true;
+}
+
+- (bool)clearCache {
+  return _esApi->ClearCache(self->_esClient);
+}
+
+- (bool)subscribe:(const std::set<es_event_type_t> &)events {
+  return _esApi->Subscribe(_esClient, events);
+}
+
+- (bool)subscribeAndClearCache:(const std::set<es_event_type_t> &)events {
+  return [self subscribe:events] && [self clearCache];
+}
+
+- (bool)respondToMessage:(const Message &)msg
+          withAuthResult:(es_auth_result_t)result
+               cacheable:(bool)cacheable {
+  return _esApi->RespondAuthResult(_esClient, msg, result, cacheable);
+}
+
+- (void)processEnrichedMessage:(std::shared_ptr<EnrichedMessage>)msg
+                       handler:(void (^)(std::shared_ptr<EnrichedMessage>))messageHandler {
+  dispatch_async(_notifyQueue, ^{
+    messageHandler(std::move(msg));
+  });
+}
+
+- (void)processMessage:(Message &&)msg handler:(void (^)(const Message &))messageHandler {
+  if (unlikely(msg->action_type != ES_ACTION_TYPE_AUTH)) {
+    // This is a programming error
+    LOGE(@"Attempting to process non-AUTH message");
+    [NSException raise:@"Attempt to process non-auth message"
+                format:@"Unexpected event type received: %d", msg->event_type];
+  }
+
+  dispatch_semaphore_t processingSema = dispatch_semaphore_create(0);
+  // Add 1 to the processing semaphore. We're not creating it with a starting
+  // value of 1 because that requires that the semaphore is not deallocated
+  // until its value matches the starting value, which we don't need.
+  dispatch_semaphore_signal(processingSema);
+  dispatch_semaphore_t deadlineExpiredSema = dispatch_semaphore_create(0);
+
+  const uint64_t timeout = NSEC_PER_MSEC * (self.deadlineMarginMS);
+  uint64_t deadlineMachTime = msg->deadline - mach_absolute_time();
+  uint64_t deadlineNano = deadlineMachTime * _timebase.numer / _timebase.denom;
+
+  // TODO(mlw): How should we handle `deadlineNano <= timeout`. Will currently
+  // result in the deadline block being dispatched immediately (and therefore
+  // the event will be denied).
+
+  // Workaround for compiler bug that doesn't properly close over variables
+  // Note: On macOS 10.15 this will cause extra message copies.
+  __block Message processMsg = msg;
+  __block Message deadlineMsg = msg;
+
+  dispatch_after(
+    dispatch_time(DISPATCH_TIME_NOW, deadlineNano - timeout), self->_authQueue, ^(void) {
+      if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
+        // Handler has already responded, nothing to do.
+        return;
+      }
+
+      bool res = [self respondToMessage:deadlineMsg
+                         withAuthResult:ES_AUTH_RESULT_DENY
+                              cacheable:false];
+
+      LOGE(@"SNTEndpointSecurityClient: deadline reached: deny pid=%d, event type: %d ret=%d",
+           audit_token_to_pid(deadlineMsg->process->audit_token), deadlineMsg->event_type, res);
+      dispatch_semaphore_signal(deadlineExpiredSema);
+    });
+
+  dispatch_async(self->_authQueue, ^{
+    messageHandler(deadlineMsg);
+    if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
+      // Deadline expired, wait for deadline block to finish.
+      dispatch_semaphore_wait(deadlineExpiredSema, DISPATCH_TIME_FOREVER);
+    }
+  });
+}
+
++ (bool)isDatabasePath:(const std::string_view)path {
+  // TODO(mlw): These values should come from `SNTDatabaseController`. But right
+  // now they live as NSStrings. We should make them `std::string_view` types
+  // in order to use them here efficiently, but will need to make the
+  // `SNTDatabaseController` an ObjC++ file.
+  return (path == "/private/var/db/santa/rules.db" || path == "/private/var/db/santa/events.db");
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityClientBase.h

@@ -0,0 +1,73 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#include <bsm/libbsm.h>
+
+#include <memory>
+#include <string>
+
+#import <Foundation/Foundation.h>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+@protocol SNTEndpointSecurityClientBase
+
+- (instancetype)initWithESAPI:
+  (std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI>)esApi;
+
+/// @note If this fails to establish a new ES client via `es_new_client`, an exception is raised
+/// that should terminate the program.
+- (void)establishClientOrDie;
+
+- (bool)subscribe:(const std::set<es_event_type_t> &)events;
+
+/// Clears the ES cache after setting subscriptions.
+/// There's a gap between creating a client and subscribing to events. Creating
+/// the client triggers a cache flush automatically but any events that happen
+/// prior to subscribing could've been cached by another client. Clearing after
+/// subscribing mitigates this posibility.
+- (bool)subscribeAndClearCache:(const std::set<es_event_type_t> &)events;
+
+/// Responds to the Message with the given auth result
+///
+/// @param Message The wrapped es_message_t being responded to
+/// @param result Either ES_AUTH_RESULT_ALLOW or ES_AUTH_RESULT_DENY
+/// @param cacheable true if ES should attempt to cache the result, otherwise false
+/// @return true if the response was successful, otherwise false
+- (bool)respondToMessage:(const santa::santad::event_providers::endpoint_security::Message &)msg
+          withAuthResult:(es_auth_result_t)result
+               cacheable:(bool)cacheable;
+
+- (void)
+  processEnrichedMessage:
+    (std::shared_ptr<santa::santad::event_providers::endpoint_security::EnrichedMessage>)msg
+                 handler:
+                   (void (^)(std::shared_ptr<
+                             santa::santad::event_providers::endpoint_security::EnrichedMessage>))
+                     messageHandler;
+
+- (void)processMessage:(santa::santad::event_providers::endpoint_security::Message &&)msg
+               handler:
+                 (void (^)(const santa::santad::event_providers::endpoint_security::Message &))
+                   messageHandler;
+
+- (bool)clearCache;
+
++ (bool)isDatabasePath:(const std::string_view)path;
++ (bool)populateAuditTokenSelf:(audit_token_t *)tok;
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityClientTest.mm

@@ -0,0 +1,395 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <bsm/libbsm.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <mach/mach_time.h>
+
+#include <memory>
+
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+using santa::santad::event_providers::endpoint_security::EnrichedClose;
+using santa::santad::event_providers::endpoint_security::EnrichedFile;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::EnrichedProcess;
+using santa::santad::event_providers::endpoint_security::Message;
+
+@interface SNTEndpointSecurityClient (Testing)
+- (void)establishClientOrDie;
+- (bool)muteSelf;
+- (NSString *)errorMessageForNewClientResult:(es_new_client_result_t)result;
+- (void)handleMessage:(Message &&)esMsg;
+- (BOOL)shouldHandleMessage:(const Message &)esMsg
+     ignoringOtherESClients:(BOOL)ignoringOtherESClients;
+
+@property int64_t deadlineMarginMS;
+@end
+
+@interface SNTEndpointSecurityClientTest : XCTestCase
+@end
+
+@implementation SNTEndpointSecurityClientTest
+
+- (void)testEstablishClientOrDie {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  EXPECT_CALL(*mockESApi, MuteProcess).WillOnce(testing::Return(true));
+
+  EXPECT_CALL(*mockESApi, NewClient)
+    .WillOnce(testing::Return(Client()))
+    .WillOnce(testing::Return(Client(nullptr, ES_NEW_CLIENT_RESULT_SUCCESS)));
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  // First time throws because mock triggers failed connection
+  // Second time succeeds
+  XCTAssertThrows([client establishClientOrDie]);
+  XCTAssertNoThrow([client establishClientOrDie]);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testErrorMessageForNewClientResult {
+  std::map<es_new_client_result_t, std::string> resultMessagePairs{
+    {ES_NEW_CLIENT_RESULT_SUCCESS, ""},
+    {ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED, "Full-disk access not granted"},
+    {ES_NEW_CLIENT_RESULT_ERR_NOT_ENTITLED, "Not entitled"},
+    {ES_NEW_CLIENT_RESULT_ERR_NOT_PRIVILEGED, "Not running as root"},
+    {ES_NEW_CLIENT_RESULT_ERR_INVALID_ARGUMENT, "Invalid argument"},
+    {ES_NEW_CLIENT_RESULT_ERR_INTERNAL, "Internal error"},
+    {ES_NEW_CLIENT_RESULT_ERR_TOO_MANY_CLIENTS, "Too many simultaneous clients"},
+    {(es_new_client_result_t)123, "Unknown error"},
+  };
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:nullptr];
+
+  for (const auto &kv : resultMessagePairs) {
+    NSString *message = [client errorMessageForNewClientResult:kv.first];
+    XCTAssertEqual(0, strcmp([(message ?: @"") UTF8String], kv.second.c_str()));
+  }
+}
+
+- (void)testHandleMessage {
+  es_message_t esMsg;
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  { XCTAssertThrows([client handleMessage:Message(mockESApi, &esMsg)]); }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testHandleMessageWithClient {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_FORK, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  // Have subscribe fail the first time, meaning clear cache only called once.
+  EXPECT_CALL(*mockESApi, RespondAuthResult(testing::_, testing::_, ES_AUTH_RESULT_ALLOW, true))
+    .WillOnce(testing::Return(true));
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  {
+    Message msg(mockESApi, &esMsg);
+
+    // Is ES client, but don't ignore others == Should Handle
+    esMsg.process->is_es_client = true;
+    XCTAssertTrue([client shouldHandleMessage:msg ignoringOtherESClients:NO]);
+
+    // Not ES client, but ignore others == Should Handle
+    esMsg.process->is_es_client = false;
+    XCTAssertTrue([client shouldHandleMessage:msg ignoringOtherESClients:YES]);
+
+    // Is ES client, don't ignore others, and non-AUTH == Don't Handle
+    esMsg.process->is_es_client = true;
+    XCTAssertFalse([client shouldHandleMessage:msg ignoringOtherESClients:YES]);
+
+    // Is ES client, don't ignore others, and AUTH == Respond and Don't Handle
+    esMsg.process->is_es_client = true;
+    esMsg.action_type = ES_ACTION_TYPE_AUTH;
+    XCTAssertFalse([client shouldHandleMessage:msg ignoringOtherESClients:YES]);
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testPopulateAuditTokenSelf {
+  audit_token_t myAuditToken;
+
+  [SNTEndpointSecurityClient populateAuditTokenSelf:&myAuditToken];
+
+  XCTAssertEqual(audit_token_to_pid(myAuditToken), getpid());
+  XCTAssertNotEqual(audit_token_to_pidversion(myAuditToken), 0);
+}
+
+- (void)testMuteSelf {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  EXPECT_CALL(*mockESApi, MuteProcess)
+    .WillOnce(testing::Return(true))
+    .WillOnce(testing::Return(false));
+
+  XCTAssertTrue([client muteSelf]);
+  XCTAssertFalse([client muteSelf]);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testClearCache {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  // Test the underlying clear cache impl returning both true and false
+  EXPECT_CALL(*mockESApi, ClearCache)
+    .WillOnce(testing::Return(true))
+    .WillOnce(testing::Return(false));
+
+  XCTAssertTrue([client clearCache]);
+  XCTAssertFalse([client clearCache]);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testSubscribe {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  std::set<es_event_type_t> events = {
+    ES_EVENT_TYPE_NOTIFY_CLOSE,
+    ES_EVENT_TYPE_NOTIFY_EXIT,
+  };
+
+  // Test the underlying subscribe impl returning both true and false
+  EXPECT_CALL(*mockESApi, Subscribe(testing::_, events))
+    .WillOnce(testing::Return(true))
+    .WillOnce(testing::Return(false));
+
+  XCTAssertTrue([client subscribe:events]);
+  XCTAssertFalse([client subscribe:events]);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testSubscribeAndClearCache {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  // Have subscribe fail the first time, meaning clear cache only called once.
+  EXPECT_CALL(*mockESApi, ClearCache)
+    .After(EXPECT_CALL(*mockESApi, Subscribe)
+             .WillOnce(testing::Return(false))
+             .WillOnce(testing::Return(true)))
+    .WillOnce(testing::Return(true));
+
+  XCTAssertFalse([client subscribeAndClearCache:{}]);
+  XCTAssertTrue([client subscribeAndClearCache:{}]);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testRespondToMessageWithAuthResultCacheable {
+  es_message_t esMsg;
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  es_auth_result_t result = ES_AUTH_RESULT_DENY;
+  bool cacheable = true;
+
+  // Have subscribe fail the first time, meaning clear cache only called once.
+  EXPECT_CALL(*mockESApi, RespondAuthResult(testing::_, testing::_, result, cacheable))
+    .WillOnce(testing::Return(true));
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  {
+    Message msg(mockESApi, &esMsg);
+    XCTAssertTrue([client respondToMessage:msg withAuthResult:result cacheable:cacheable]);
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testProcessEnrichedMessageHandler {
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  // Note: In this test, `RetainMessage` isn't setup to return anything. This
+  // means that the underlying `es_msg_` in the `Message` object is NULL, and
+  // therefore no call to `ReleaseMessage` is ever made (hence no expectations).
+  // Because we don't need to operate on the es_msg_, this simplifies the test.
+  EXPECT_CALL(*mockESApi, RetainMessage);
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  es_message_t esMsg;
+  auto enrichedMsg = std::make_shared<EnrichedMessage>(
+    EnrichedClose(Message(mockESApi, &esMsg),
+                  EnrichedProcess(std::nullopt, std::nullopt, std::nullopt, std::nullopt,
+                                  EnrichedFile(std::nullopt, std::nullopt, std::nullopt)),
+                  EnrichedFile(std::nullopt, std::nullopt, std::nullopt)));
+
+  [client processEnrichedMessage:enrichedMsg
+                         handler:^(std::shared_ptr<EnrichedMessage> msg) {
+                           dispatch_semaphore_signal(sema);
+                         }];
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+                 "Handler block not called within expected time window");
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testIsDatabasePath {
+  XCTAssertTrue([SNTEndpointSecurityClient isDatabasePath:"/private/var/db/santa/rules.db"]);
+  XCTAssertTrue([SNTEndpointSecurityClient isDatabasePath:"/private/var/db/santa/events.db"]);
+
+  XCTAssertFalse([SNTEndpointSecurityClient isDatabasePath:"/not/a/db/path"]);
+}
+
+- (void)testProcessMessageHandlerBadEventType {
+  es_file_t proc_file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&proc_file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXIT, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  {
+    XCTAssertThrows([client processMessage:Message(mockESApi, &esMsg)
+                                   handler:^(const Message &msg){
+                                   }]);
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+// Note: This test triggers a leak warning on the mock object, however it is
+// benign. The dispatch block to handle deadline expiration in
+// `processMessage:handler:` will retain the mock object an extra time.
+// But since this test sets a long deadline in order to ensure the handler block
+// runs first, the deadline handler block will not have finished executing by
+// the time the test exits, making GMock think the object was leaked.
+- (void)testProcessMessageHandler {
+  es_file_t proc_file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&proc_file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_OPEN, &proc, ActionType::Auth,
+                                     45 * 1000);  // Long deadline to not hit
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+
+  {
+    XCTAssertNoThrow([client processMessage:Message(mockESApi, &esMsg)
+                                    handler:^(const Message &msg) {
+                                      dispatch_semaphore_signal(sema);
+                                    }]);
+  }
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 5 * NSEC_PER_SEC)),
+                 "Handler block not called within expected time window");
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testProcessMessageHandlerWithDeadlineTimeout {
+  // Set a es_message_t deadline of 750ms
+  // Set a deadline leeway in the `SNTEndpointSecurityClient` of 500ms
+  // Mock `RespondAuthResult` which is called from the deadline handler
+  // Signal the semaphore from the mock
+  // Wait a few seconds for the semaphore (should take ~250ms)
+  //
+  // Two semaphotes are used:
+  // 1. deadlineSema - used to wait in the handler block until the deadline
+  //    block has a chance to execute
+  // 2. controlSema - used to block control flow in the test until the
+  //    deadlineSema is signaled (or a timeout waiting on deadlineSema)
+  es_file_t proc_file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&proc_file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_OPEN, &proc, ActionType::Auth,
+                                     750);  // 750ms timeout
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  dispatch_semaphore_t deadlineSema = dispatch_semaphore_create(0);
+  dispatch_semaphore_t controlSema = dispatch_semaphore_create(0);
+
+  EXPECT_CALL(*mockESApi, RespondAuthResult(testing::_, testing::_, ES_AUTH_RESULT_DENY, false))
+    .WillOnce(testing::InvokeWithoutArgs(^() {
+      // Signal deadlineSema to let the handler block continue execution
+      dispatch_semaphore_signal(deadlineSema);
+      return true;
+    }));
+
+  SNTEndpointSecurityClient *client = [[SNTEndpointSecurityClient alloc] initWithESAPI:mockESApi];
+  client.deadlineMarginMS = 500;
+
+  {
+    __block long result;
+    XCTAssertNoThrow([client processMessage:Message(mockESApi, &esMsg)
+                                    handler:^(const Message &msg) {
+                                      result = dispatch_semaphore_wait(
+                                        deadlineSema,
+                                        dispatch_time(DISPATCH_TIME_NOW, 4 * NSEC_PER_SEC));
+
+                                      // Once done waiting on deadlineSema, trigger controlSema to
+                                      // continue test
+                                      dispatch_semaphore_signal(controlSema);
+                                    }]);
+
+    XCTAssertEqual(
+      0, dispatch_semaphore_wait(controlSema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+      "Control sema not signaled within expected time window");
+
+    XCTAssertEqual(result, 0);
+  }
+
+  // Allow some time for the threads in `processMessage:handler:` to finish.
+  // It isn't critical that they do, but if the dispatch blocks don't complete
+  // we may get warnings from GMock about calls to ReleaseMessage after
+  // verifying and clearing. Sleep a little bit here to reduce chances of
+  // seeing the warning (but still possible)
+  SleepMS(100);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityDeviceManager.h

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2021-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -11,12 +11,16 @@
 ///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
-#import <DiskArbitration/DiskArbitration.h>
+
+#include <DiskArbitration/DiskArbitration.h>
 #import <Foundation/Foundation.h>
 
-#include <EndpointSecurity/EndpointSecurity.h>
-
-#include "Source/common/SNTDeviceEvent.h"
+#import "Source/common/SNTDeviceEvent.h"
+#import "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityEventHandler.h"
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -26,16 +30,18 @@ typedef void (^SNTDeviceBlockCallback)(SNTDeviceEvent *event);
  * Manages DiskArbitration and EndpointSecurity to monitor/block/remount USB
  * storage devices.
  */
-@interface SNTDeviceManager : NSObject
+@interface SNTEndpointSecurityDeviceManager
+    : SNTEndpointSecurityClient <SNTEndpointSecurityEventHandler>
 
-@property(nonatomic, readwrite) BOOL subscribed;
 @property(nonatomic, readwrite) BOOL blockUSBMount;
 @property(nonatomic, readwrite, nullable) NSArray<NSString *> *remountArgs;
 @property(nonatomic, nullable) SNTDeviceBlockCallback deviceBlockCallback;
 
-- (instancetype)init;
-- (void)listen;
-- (BOOL)subscribed;
+- (instancetype)
+    initWithESAPI:
+      (std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI>)esApi
+           logger:(std::shared_ptr<santa::santad::logs::endpoint_security::Logger>)logger
+  authResultCache:(std::shared_ptr<santa::santad::event_providers::AuthResultCache>)authResultCache;
 
 @end
 

Source/santad/EventProviders/SNTEndpointSecurityDeviceManager.mm

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2021-2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -11,21 +11,39 @@
 ///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
-#import "Source/santad/EventProviders/SNTDeviceManager.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityDeviceManager.h"
 
 #import <DiskArbitration/DiskArbitration.h>
+#include <EndpointSecurity/EndpointSecurity.h>
 #import <Foundation/Foundation.h>
 
+#include <atomic>
+#include <memory>
+
 #include <bsm/libbsm.h>
 #include <errno.h>
 #include <libproc.h>
 #include <sys/mount.h>
-#include <atomic>
-#include <memory>
 
 #import "Source/common/SNTDeviceEvent.h"
 #import "Source/common/SNTLogging.h"
-#import "Source/santad/Logs/SNTEventLog.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::FlushCacheMode;
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::Logger;
+
+@interface SNTEndpointSecurityDeviceManager ()
+
+- (void)logDiskAppeared:(NSDictionary *)props;
+- (void)logDiskDisappeared:(NSDictionary *)props;
+
+@property DASessionRef diskArbSession;
+@property(nonatomic, readonly) dispatch_queue_t diskQueue;
+
+@end
 
 void diskMountedCallback(DADiskRef disk, DADissenterRef dissenter, void *context) {
   if (dissenter) {
@@ -36,17 +54,18 @@ void diskMountedCallback(DADiskRef disk, DADissenterRef dissenter, void *context
     IOReturn subSystemCode = err_get_sub(status);
     IOReturn errorCode = err_get_code(status);
 
-    LOGE(
-      @"SNTDeviceManager: dissenter status codes: system: %d, subsystem: %d, err: %d; status: %s",
-      systemCode, subSystemCode, errorCode, [statusString UTF8String]);
+    LOGE(@"SNTEndpointSecurityDeviceManager: dissenter status codes: system: %d, subsystem: %d, "
+         @"err: %d; status: %s",
+         systemCode, subSystemCode, errorCode, [statusString UTF8String]);
   }
 }
 
 void diskAppearedCallback(DADiskRef disk, void *context) {
   NSDictionary *props = CFBridgingRelease(DADiskCopyDescription(disk));
   if (![props[@"DAVolumeMountable"] boolValue]) return;
-  SNTEventLog *logger = [SNTEventLog logger];
-  if (logger) [logger logDiskAppeared:props];
+  SNTEndpointSecurityDeviceManager *dm = (__bridge SNTEndpointSecurityDeviceManager *)context;
+
+  [dm logDiskAppeared:props];
 }
 
 void diskDescriptionChangedCallback(DADiskRef disk, CFArrayRef keys, void *context) {
@@ -54,8 +73,9 @@ void diskDescriptionChangedCallback(DADiskRef disk, CFArrayRef keys, void *conte
   if (![props[@"DAVolumeMountable"] boolValue]) return;
 
   if (props[@"DAVolumePath"]) {
-    SNTEventLog *logger = [SNTEventLog logger];
-    if (logger) [logger logDiskAppeared:props];
+    SNTEndpointSecurityDeviceManager *dm = (__bridge SNTEndpointSecurityDeviceManager *)context;
+
+    [dm logDiskAppeared:props];
   }
 }
 
@@ -63,8 +83,9 @@ void diskDisappearedCallback(DADiskRef disk, void *context) {
   NSDictionary *props = CFBridgingRelease(DADiskCopyDescription(disk));
   if (![props[@"DAVolumeMountable"] boolValue]) return;
 
-  SNTEventLog *logger = [SNTEventLog logger];
-  if (logger) [logger logDiskDisappeared:props];
+  SNTEndpointSecurityDeviceManager *dm = (__bridge SNTEndpointSecurityDeviceManager *)context;
+
+  [dm logDiskDisappeared:props];
 }
 
 NSArray<NSString *> *maskToMountArgs(long remountOpts) {
@@ -101,126 +122,97 @@ long mountArgsToMask(NSArray<NSString *> *args) {
     else if ([arg isEqualToString:@"async"])
       flags |= MNT_ASYNC;
     else
-      LOGE(@"SNTDeviceManager: unexpected mount arg: %@", arg);
+      LOGE(@"SNTEndpointSecurityDeviceManager: unexpected mount arg: %@", arg);
   }
   return flags;
 }
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface SNTDeviceManager ()
+@implementation SNTEndpointSecurityDeviceManager {
+  std::shared_ptr<AuthResultCache> _authResultCache;
+  std::shared_ptr<Logger> _logger;
+}
 
-@property DASessionRef diskArbSession;
-@property(nonatomic, readonly) es_client_t *client;
-@property(nonatomic, readonly) dispatch_queue_t esAuthQueue;
-@property(nonatomic, readonly) dispatch_queue_t diskQueue;
-@end
-
-@implementation SNTDeviceManager
-
-- (instancetype)init API_AVAILABLE(macos(10.15)) {
-  self = [super init];
+- (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi
+                       logger:(std::shared_ptr<Logger>)logger
+              authResultCache:(std::shared_ptr<AuthResultCache>)authResultCache {
+  self = [super initWithESAPI:std::move(esApi)];
   if (self) {
+    _logger = logger;
+    _authResultCache = authResultCache;
     _blockUSBMount = false;
 
-    _diskQueue = dispatch_queue_create("com.google.santad.disk_queue", DISPATCH_QUEUE_SERIAL);
-
-    _esAuthQueue =
-      dispatch_queue_create("com.google.santa.daemon.es_device_auth", DISPATCH_QUEUE_CONCURRENT);
+    _diskQueue = dispatch_queue_create("com.google.santa.daemon.disk_queue", DISPATCH_QUEUE_SERIAL);
 
     _diskArbSession = DASessionCreate(NULL);
     DASessionSetDispatchQueue(_diskArbSession, _diskQueue);
 
-    if (@available(macos 10.15, *)) [self initES];
+    [self establishClientOrDie];
   }
   return self;
 }
 
-- (void)initES API_AVAILABLE(macos(10.15)) {
-  while (!self.client) {
-    es_client_t *client = NULL;
-    es_new_client_result_t ret = es_new_client(&client, ^(es_client_t *c, const es_message_t *m) {
-      // Set timeout to 5 seconds before the ES deadline.
-      [self handleESMessageWithTimeout:m
-                            withClient:c
-                               timeout:dispatch_time(m->deadline, NSEC_PER_SEC * -5)];
-    });
+- (void)logDiskAppeared:(NSDictionary *)props {
+  self->_logger->LogDiskAppeared(props);
+}
 
-    switch (ret) {
-      case ES_NEW_CLIENT_RESULT_SUCCESS:
-        LOGI(@"Connected to EndpointSecurity");
-        _client = client;
-        return;
-      case ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED:
-        LOGE(@"Unable to create EndpointSecurity client, not full-disk access permitted");
-        LOGE(@"Sleeping for 30s before restarting.");
-        sleep(30);
-        exit(ret);
-      default:
-        LOGE(@"Unable to create es client: %d. Sleeping for a minute.", ret);
-        sleep(60);
-        continue;
-    }
+- (void)logDiskDisappeared:(NSDictionary *)props {
+  self->_logger->LogDiskDisappeared(props);
+}
+
+- (void)handleMessage:(Message &&)esMsg {
+  if (!self.blockUSBMount) {
+    // TODO: We should also unsubscribe from events when this isn't set, but
+    // this is generally a low-volume event type.
+    [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_ALLOW cacheable:false];
+    return;
   }
+
+  if (esMsg->event_type == ES_EVENT_TYPE_NOTIFY_UNMOUNT) {
+    self->_authResultCache->FlushCache(FlushCacheMode::kNonRootOnly);
+    return;
+  }
+
+  [self processMessage:std::move(esMsg)
+               handler:^(const Message &msg) {
+                 es_auth_result_t result = [self handleAuthMount:msg];
+                 [self respondToMessage:msg withAuthResult:result cacheable:false];
+               }];
 }
 
-- (void)listenES API_AVAILABLE(macos(10.15)) {
-  while (!self.client)
-    usleep(100000);  // 100ms
-
-  es_event_type_t events[] = {
-    ES_EVENT_TYPE_AUTH_MOUNT,
-    ES_EVENT_TYPE_AUTH_REMOUNT,
-  };
-
-  es_return_t sret = es_subscribe(self.client, events, sizeof(events) / sizeof(es_event_type_t));
-  if (sret != ES_RETURN_SUCCESS)
-    LOGE(@"SNTDeviceManager: unable to subscribe to auth mount events: %d", sret);
-}
-
-- (void)listenDA {
+- (void)enable {
   DARegisterDiskAppearedCallback(_diskArbSession, NULL, diskAppearedCallback,
                                  (__bridge void *)self);
   DARegisterDiskDescriptionChangedCallback(_diskArbSession, NULL, NULL,
                                            diskDescriptionChangedCallback, (__bridge void *)self);
   DARegisterDiskDisappearedCallback(_diskArbSession, NULL, diskDisappearedCallback,
                                     (__bridge void *)self);
+
+  [super subscribeAndClearCache:{
+                                  ES_EVENT_TYPE_AUTH_MOUNT,
+                                  ES_EVENT_TYPE_AUTH_REMOUNT,
+                                  ES_EVENT_TYPE_NOTIFY_UNMOUNT,
+                                }];
 }
 
-- (void)listen {
-  [self listenDA];
-  if (@available(macos 10.15, *)) [self listenES];
-  self.subscribed = YES;
-}
-
-- (void)handleAuthMount:(const es_message_t *)m
-             withClient:(es_client_t *)c API_AVAILABLE(macos(10.15)) {
-  if (!self.blockUSBMount) {
-    es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, false);
-    return;
-  }
-
+- (es_auth_result_t)handleAuthMount:(const Message &)m {
   struct statfs *eventStatFS;
-  BOOL isRemount = NO;
 
   switch (m->event_type) {
     case ES_EVENT_TYPE_AUTH_MOUNT: eventStatFS = m->event.mount.statfs; break;
-    case ES_EVENT_TYPE_AUTH_REMOUNT:
-      eventStatFS = m->event.remount.statfs;
-      isRemount = YES;
-      break;
+    case ES_EVENT_TYPE_AUTH_REMOUNT: eventStatFS = m->event.remount.statfs; break;
     default:
+      // This is a programming error
       LOGE(@"Unexpected Event Type passed to DeviceManager handleAuthMount: %d", m->event_type);
-      // Fail closed.
-      es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, false);
-      assert(0 && "SNTDeviceManager: unexpected event type");
-      return;
+      exit(EXIT_FAILURE);
   }
 
   long mountMode = eventStatFS->f_flags;
   pid_t pid = audit_token_to_pid(m->process->audit_token);
-  LOGD(@"SNTDeviceManager: mount syscall arriving from path: %s, pid: %d, fflags: %lu",
-       m->process->executable->path.data, pid, mountMode);
+  LOGD(
+    @"SNTEndpointSecurityDeviceManager: mount syscall arriving from path: %s, pid: %d, fflags: %lu",
+    m->process->executable->path.data, pid, mountMode);
 
   DADiskRef disk = DADiskCreateFromBSDName(NULL, self.diskArbSession, eventStatFS->f_mntfromname);
   CFAutorelease(disk);
@@ -232,12 +224,13 @@ NS_ASSUME_NONNULL_BEGIN
   BOOL isEjectable = [diskInfo[(__bridge NSString *)kDADiskDescriptionMediaEjectableKey] boolValue];
   NSString *protocol = diskInfo[(__bridge NSString *)kDADiskDescriptionDeviceProtocolKey];
   BOOL isUSB = [protocol isEqualToString:@"USB"];
-  BOOL isVirtual = [protocol isEqualToString: @"Virtual Interface"];
+  BOOL isVirtual = [protocol isEqualToString:@"Virtual Interface"];
 
   NSString *kind = diskInfo[(__bridge NSString *)kDADiskDescriptionMediaKindKey];
 
   // TODO: check kind and protocol for banned things (e.g. MTP).
-  LOGD(@"SNTDeviceManager: DiskInfo Protocol: %@ Kind: %@ isInternal: %d isRemovable: %d "
+  LOGD(@"SNTEndpointSecurityDeviceManager: DiskInfo Protocol: %@ Kind: %@ isInternal: %d "
+       @"isRemovable: %d "
        @"isEjectable: %d",
        protocol, kind, isInternal, isRemovable, isEjectable);
 
@@ -245,8 +238,7 @@ NS_ASSUME_NONNULL_BEGIN
   // also are okay with operations for devices that are non-removal as long as
   // they are NOT a USB device.
   if (isInternal || isVirtual || (!isRemovable && !isEjectable && !isUSB)) {
-    es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, false);
-    return;
+    return ES_AUTH_RESULT_ALLOW;
   }
 
   SNTDeviceEvent *event = [[SNTDeviceEvent alloc]
@@ -259,17 +251,16 @@ NS_ASSUME_NONNULL_BEGIN
     event.remountArgs = self.remountArgs;
     long remountOpts = mountArgsToMask(self.remountArgs);
 
-    LOGD(@"SNTDeviceManager: mountMode: %@", maskToMountArgs(mountMode));
-    LOGD(@"SNTDeviceManager: remountOpts: %@", maskToMountArgs(remountOpts));
+    LOGD(@"SNTEndpointSecurityDeviceManager: mountMode: %@", maskToMountArgs(mountMode));
+    LOGD(@"SNTEndpointSecurityDeviceManager: remountOpts: %@", maskToMountArgs(remountOpts));
 
-    if ((mountMode & remountOpts) == remountOpts && !isRemount) {
-      LOGD(@"SNTDeviceManager: Allowing as mount as flags match remountOpts");
-      es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, false);
-      return;
+    if ((mountMode & remountOpts) == remountOpts && m->event_type != ES_EVENT_TYPE_AUTH_REMOUNT) {
+      LOGD(@"SNTEndpointSecurityDeviceManager: Allowing as mount as flags match remountOpts");
+      return ES_AUTH_RESULT_ALLOW;
     }
 
     long newMode = mountMode | remountOpts;
-    LOGI(@"SNTDeviceManager: remounting device '%s'->'%s', flags (%lu) -> (%lu)",
+    LOGI(@"SNTEndpointSecurityDeviceManager: remounting device '%s'->'%s', flags (%lu) -> (%lu)",
          eventStatFS->f_mntfromname, eventStatFS->f_mntonname, mountMode, newMode);
     [self remount:disk mountMode:newMode];
   }
@@ -278,7 +269,7 @@ NS_ASSUME_NONNULL_BEGIN
     self.deviceBlockCallback(event);
   }
 
-  es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, false);
+  return ES_AUTH_RESULT_DENY;
 }
 
 - (void)remount:(DADiskRef)disk mountMode:(long)remountMask {
@@ -293,66 +284,6 @@ NS_ASSUME_NONNULL_BEGIN
   free(argv);
 }
 
-// handleESMessage handles an ES message synchronously. This will block all incoming ES events
-// until either we serve a response or we hit the auth deadline. Prefer [SNTDeviceManager
-// handleESMessageWithTimeout]
-// TODO(tnek): generalize this timeout handling logic so that EndpointSecurityManager can use it
-// too.
-- (void)handleESMessageWithTimeout:(const es_message_t *)m
-                        withClient:(es_client_t *)c
-                           timeout:(dispatch_time_t)timeout API_AVAILABLE(macos(10.15)) {
-  // ES will kill our whole client if we don't meet the es_message auth deadline, so we try to
-  // gracefully handle it with a deny-by-default in the worst-case before it can do that.
-  // This isn't an issue for notify events, so we're in no rush for those.
-  es_message_t *mc = es_copy_message(m);
-
-  dispatch_semaphore_t processingSema = dispatch_semaphore_create(0);
-  // Add 1 to the processing semaphore. We're not creating it with a starting
-  // value of 1 because that requires that the semaphore is not deallocated
-  // until its value matches the starting value, which we don't need.
-  dispatch_semaphore_signal(processingSema);
-  dispatch_semaphore_t deadlineExpiredSema = dispatch_semaphore_create(0);
-
-  if (mc->action_type == ES_ACTION_TYPE_AUTH) {
-    dispatch_after(timeout, self.esAuthQueue, ^(void) {
-      if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
-        // Handler already responded, nothing to do.
-        return;
-      }
-      LOGE(@"SNTDeviceManager: deadline reached: deny pid=%d ret=%d",
-           audit_token_to_pid(mc->process->audit_token),
-           es_respond_auth_result(c, mc, ES_AUTH_RESULT_DENY, false));
-      dispatch_semaphore_signal(deadlineExpiredSema);
-    });
-  }
-
-  dispatch_async(self.esAuthQueue, ^{
-    [self handleESMessage:mc withClient:c];
-    if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
-      // Deadline expired, wait for deadline block to finish.
-      dispatch_semaphore_wait(deadlineExpiredSema, DISPATCH_TIME_FOREVER);
-    }
-    es_free_message(mc);
-  });
-}
-
-- (void)handleESMessage:(const es_message_t *)m
-             withClient:(es_client_t *)c API_AVAILABLE(macos(10.15)) {
-  switch (m->event_type) {
-    case ES_EVENT_TYPE_AUTH_REMOUNT: {
-      [[fallthrough]];
-    }
-    case ES_EVENT_TYPE_AUTH_MOUNT: {
-      [self handleAuthMount:m withClient:c];
-      break;
-    }
-
-    default:
-      LOGE(@"SNTDeviceManager: unexpected event type: %d", m->event_type);
-      break;
-  }
-}
-
 @end
 
 NS_ASSUME_NONNULL_END

Source/santad/EventProviders/SNTEndpointSecurityDeviceManagerTest.mm

@@ -0,0 +1,347 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <DiskArbitration/DiskArbitration.h>
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#import <bsm/libbsm.h>
+#import <dispatch/dispatch.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <sys/mount.h>
+
+#include <memory>
+#include <set>
+
+#import "Source/common/SNTConfigurator.h"
+#import "Source/common/SNTDeviceEvent.h"
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/AuthResultCache.h"
+#import "Source/santad/EventProviders/DiskArbitrationTestUtil.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityDeviceManager.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::FlushCacheMode;
+using santa::santad::event_providers::endpoint_security::Message;
+
+class MockAuthResultCache : public AuthResultCache {
+ public:
+  using AuthResultCache::AuthResultCache;
+
+  MOCK_METHOD(void, FlushCache, (FlushCacheMode mode));
+};
+
+@interface SNTEndpointSecurityDeviceManager (Testing)
+- (void)logDiskAppeared:(NSDictionary *)props;
+@end
+
+@interface SNTEndpointSecurityDeviceManagerTest : XCTestCase
+@property id mockConfigurator;
+@property MockDiskArbitration *mockDA;
+@end
+
+@implementation SNTEndpointSecurityDeviceManagerTest
+
+- (void)setUp {
+  [super setUp];
+
+  self.mockConfigurator = OCMClassMock([SNTConfigurator class]);
+  OCMStub([self.mockConfigurator configurator]).andReturn(self.mockConfigurator);
+  OCMStub([self.mockConfigurator eventLogType]).andReturn(-1);
+
+  self.mockDA = [MockDiskArbitration mockDiskArbitration];
+  [self.mockDA reset];
+
+  fclose(stdout);
+}
+
+- (void)triggerTestMountEvent:(es_event_type_t)eventType
+            diskInfoOverrides:(NSDictionary *)diskInfo
+           expectedAuthResult:(es_auth_result_t)expectedAuthResult
+           deviceManagerSetup:(void (^)(SNTEndpointSecurityDeviceManager *))setupDMCallback {
+  struct statfs fs = {0};
+  NSString *test_mntfromname = @"/dev/disk2s1";
+  NSString *test_mntonname = @"/Volumes/KATE'S 4G";
+
+  strncpy(fs.f_mntfromname, [test_mntfromname UTF8String], sizeof(fs.f_mntfromname));
+  strncpy(fs.f_mntonname, [test_mntonname UTF8String], sizeof(fs.f_mntonname));
+
+  MockDADisk *disk = [[MockDADisk alloc] init];
+  disk.diskDescription = @{
+    (__bridge NSString *)kDADiskDescriptionDeviceProtocolKey : @"USB",
+    (__bridge NSString *)kDADiskDescriptionMediaRemovableKey : @YES,
+    @"DAVolumeMountable" : @YES,
+    @"DAVolumePath" : test_mntonname,
+    @"DADeviceModel" : @"Some device model",
+    @"DADevicePath" : test_mntonname,
+    @"DADeviceVendor" : @"Some vendor",
+    @"DAAppearanceTime" : @0,
+    @"DAMediaBSDName" : test_mntfromname,
+  };
+
+  if (diskInfo != nil) {
+    NSMutableDictionary *mergedDiskDescription = [disk.diskDescription mutableCopy];
+    for (NSString *key in diskInfo) {
+      mergedDiskDescription[key] = diskInfo[key];
+    }
+    disk.diskDescription = (NSDictionary *)mergedDiskDescription;
+  }
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+
+  SNTEndpointSecurityDeviceManager *deviceManager =
+    [[SNTEndpointSecurityDeviceManager alloc] initWithESAPI:mockESApi
+                                                     logger:nullptr
+                                            authResultCache:nullptr];
+
+  setupDMCallback(deviceManager);
+
+  // Stub the log method since a mock `Logger` object isn't used.
+  id partialDeviceManager = OCMPartialMock(deviceManager);
+  OCMStub([partialDeviceManager logDiskAppeared:OCMOCK_ANY]);
+
+  [self.mockDA insert:disk bsdName:test_mntfromname];
+
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(eventType, &proc, ActionType::Auth, 6000);
+  // Need a pointer to esMsg to capture in blocks below.
+  es_message_t *heapESMsg = &esMsg;
+
+  __block int retainCount = 0;
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+  EXPECT_CALL(*mockESApi, ReleaseMessage).WillRepeatedly(^{
+    if (retainCount == 0) {
+      XCTFail(@"Under retain!");
+    }
+    retainCount--;
+    if (retainCount == 0) {
+      dispatch_semaphore_signal(sema);
+    }
+  });
+  EXPECT_CALL(*mockESApi, RetainMessage).WillRepeatedly(^{
+    retainCount++;
+    return heapESMsg;
+  });
+
+  if (eventType == ES_EVENT_TYPE_AUTH_MOUNT) {
+    esMsg.event.mount.statfs = &fs;
+  } else if (eventType == ES_EVENT_TYPE_AUTH_REMOUNT) {
+    esMsg.event.remount.statfs = &fs;
+  } else {
+    // Programming error. Fail the test.
+    XCTFail(@"Unhandled event type in test: %d", eventType);
+  }
+
+  XCTestExpectation *mountExpectation =
+    [self expectationWithDescription:@"Wait for response from ES"];
+
+  EXPECT_CALL(*mockESApi, RespondAuthResult(testing::_, testing::_, expectedAuthResult, false))
+    .WillOnce(testing::InvokeWithoutArgs(^bool {
+      [mountExpectation fulfill];
+      return true;
+    }));
+
+  [deviceManager handleMessage:Message(mockESApi, &esMsg)];
+
+  [self waitForExpectations:@[ mountExpectation ] timeout:60.0];
+
+  XCTAssertEqual(0,
+                 dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 5 * NSEC_PER_SEC)),
+                 "Failed waiting for message to be processed...");
+
+  [partialDeviceManager stopMocking];
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testUSBBlockDisabled {
+  [self triggerTestMountEvent:ES_EVENT_TYPE_AUTH_MOUNT
+            diskInfoOverrides:nil
+           expectedAuthResult:ES_AUTH_RESULT_ALLOW
+           deviceManagerSetup:^(SNTEndpointSecurityDeviceManager *dm) {
+             dm.blockUSBMount = NO;
+           }];
+}
+
+- (void)testRemount {
+  NSArray *wantRemountArgs = @[ @"noexec", @"rdonly" ];
+
+  XCTestExpectation *expectation =
+    [self expectationWithDescription:
+            @"Wait for SNTEndpointSecurityDeviceManager's blockCallback to trigger"];
+
+  __block NSString *gotmntonname, *gotmntfromname;
+  __block NSArray<NSString *> *gotRemountedArgs;
+
+  [self triggerTestMountEvent:ES_EVENT_TYPE_AUTH_MOUNT
+            diskInfoOverrides:nil
+           expectedAuthResult:ES_AUTH_RESULT_DENY
+           deviceManagerSetup:^(SNTEndpointSecurityDeviceManager *dm) {
+             dm.blockUSBMount = YES;
+             dm.remountArgs = wantRemountArgs;
+
+             dm.deviceBlockCallback = ^(SNTDeviceEvent *event) {
+               gotRemountedArgs = event.remountArgs;
+               gotmntonname = event.mntonname;
+               gotmntfromname = event.mntfromname;
+               [expectation fulfill];
+             };
+           }];
+
+  XCTAssertEqual(self.mockDA.wasRemounted, YES);
+
+  [self waitForExpectations:@[ expectation ] timeout:60.0];
+
+  XCTAssertEqualObjects(gotRemountedArgs, wantRemountArgs);
+  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
+  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
+}
+
+- (void)testBlockNoRemount {
+  XCTestExpectation *expectation =
+    [self expectationWithDescription:
+            @"Wait for SNTEndpointSecurityDeviceManager's blockCallback to trigger"];
+
+  __block NSString *gotmntonname, *gotmntfromname;
+  __block NSArray<NSString *> *gotRemountedArgs;
+
+  [self triggerTestMountEvent:ES_EVENT_TYPE_AUTH_MOUNT
+            diskInfoOverrides:nil
+           expectedAuthResult:ES_AUTH_RESULT_DENY
+           deviceManagerSetup:^(SNTEndpointSecurityDeviceManager *dm) {
+             dm.blockUSBMount = YES;
+
+             dm.deviceBlockCallback = ^(SNTDeviceEvent *event) {
+               gotRemountedArgs = event.remountArgs;
+               gotmntonname = event.mntonname;
+               gotmntfromname = event.mntfromname;
+               [expectation fulfill];
+             };
+           }];
+
+  [self waitForExpectations:@[ expectation ] timeout:60.0];
+
+  XCTAssertNil(gotRemountedArgs);
+  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
+  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
+}
+
+- (void)testEnsureRemountsCannotChangePerms {
+  NSArray *wantRemountArgs = @[ @"noexec", @"rdonly" ];
+
+  XCTestExpectation *expectation =
+    [self expectationWithDescription:
+            @"Wait for SNTEndpointSecurityDeviceManager's blockCallback to trigger"];
+
+  __block NSString *gotmntonname, *gotmntfromname;
+  __block NSArray<NSString *> *gotRemountedArgs;
+
+  [self triggerTestMountEvent:ES_EVENT_TYPE_AUTH_MOUNT
+            diskInfoOverrides:nil
+           expectedAuthResult:ES_AUTH_RESULT_DENY
+           deviceManagerSetup:^(SNTEndpointSecurityDeviceManager *dm) {
+             dm.blockUSBMount = YES;
+             dm.remountArgs = wantRemountArgs;
+
+             dm.deviceBlockCallback = ^(SNTDeviceEvent *event) {
+               gotRemountedArgs = event.remountArgs;
+               gotmntonname = event.mntonname;
+               gotmntfromname = event.mntfromname;
+               [expectation fulfill];
+             };
+           }];
+
+  XCTAssertEqual(self.mockDA.wasRemounted, YES);
+
+  [self waitForExpectations:@[ expectation ] timeout:10.0];
+
+  XCTAssertEqualObjects(gotRemountedArgs, wantRemountArgs);
+  XCTAssertEqualObjects(gotmntonname, @"/Volumes/KATE'S 4G");
+  XCTAssertEqualObjects(gotmntfromname, @"/dev/disk2s1");
+}
+
+- (void)testEnsureDMGsDoNotPrompt {
+  NSArray *wantRemountArgs = @[ @"noexec", @"rdonly" ];
+  NSDictionary *diskInfo = @{
+    (__bridge NSString *)kDADiskDescriptionDeviceProtocolKey : @"Virtual Interface",
+    (__bridge NSString *)kDADiskDescriptionDeviceModelKey : @"Disk Image",
+    (__bridge NSString *)kDADiskDescriptionMediaNameKey : @"disk image",
+  };
+
+  [self triggerTestMountEvent:ES_EVENT_TYPE_AUTH_MOUNT
+            diskInfoOverrides:diskInfo
+           expectedAuthResult:ES_AUTH_RESULT_ALLOW
+           deviceManagerSetup:^(SNTEndpointSecurityDeviceManager *dm) {
+             dm.blockUSBMount = YES;
+             dm.remountArgs = wantRemountArgs;
+
+             dm.deviceBlockCallback = ^(SNTDeviceEvent *event) {
+               XCTFail(@"Should not be called");
+             };
+           }];
+
+  XCTAssertEqual(self.mockDA.wasRemounted, NO);
+}
+
+- (void)testNotifyUnmountFlushesCache {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_UNMOUNT, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  auto mockAuthCache = std::make_shared<MockAuthResultCache>(nullptr);
+  EXPECT_CALL(*mockAuthCache, FlushCache);
+
+  SNTEndpointSecurityDeviceManager *deviceManager =
+    [[SNTEndpointSecurityDeviceManager alloc] initWithESAPI:mockESApi
+                                                     logger:nullptr
+                                            authResultCache:mockAuthCache];
+
+  deviceManager.blockUSBMount = YES;
+
+  [deviceManager handleMessage:Message(mockESApi, &esMsg)];
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockAuthCache.get());
+}
+
+- (void)testEnable {
+  // Ensure the client subscribes to expected event types
+  std::set<es_event_type_t> expectedEventSubs{
+    ES_EVENT_TYPE_AUTH_MOUNT,
+    ES_EVENT_TYPE_AUTH_REMOUNT,
+    ES_EVENT_TYPE_NOTIFY_UNMOUNT,
+  };
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  id deviceClient = [[SNTEndpointSecurityDeviceManager alloc] initWithESAPI:mockESApi];
+
+  EXPECT_CALL(*mockESApi, ClearCache(testing::_))
+    .After(EXPECT_CALL(*mockESApi, Subscribe(testing::_, expectedEventSubs))
+             .WillOnce(testing::Return(true)))
+    .WillOnce(testing::Return(true));
+
+  [deviceClient enable];
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityEventHandler.h

@@ -0,0 +1,32 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+#include "Source/common/SNTCommon.h"
+
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+// Protocol that all subclasses of `SNTEndpointSecurityClient` should adhere to.
+@protocol SNTEndpointSecurityEventHandler <NSObject>
+
+// Called Synchronously and serially for each message provided by the
+// EndpointSecurity framework.
+- (void)handleMessage:(santa::santad::event_providers::endpoint_security::Message &&)esMsg;
+
+// Called after Santa has finished initializing itself.
+// This is an optimal place to subscribe to ES events
+- (void)enable;
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityManager.h

@@ -1,37 +0,0 @@
-/// Copyright 2019 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import <Foundation/Foundation.h>
-
-#include "Source/common/SNTCommon.h"
-#include "Source/santad/EventProviders/SNTEventProvider.h"
-
-#include <EndpointSecurity/EndpointSecurity.h>
-
-@interface SNTEndpointSecurityManager : NSObject <SNTEventProvider>
-- (santa_vnode_id_t)vnodeIDForFile:(es_file_t *)file;
-
-- (BOOL)isCompilerPID:(pid_t)pid;
-- (void)setIsCompilerPID:(pid_t)pid;
-- (void)setNotCompilerPID:(pid_t)pid;
-
-// Returns YES if the path was truncated.
-// The populated buffer will be NUL terminated.
-+ (BOOL)populateBufferFromESFile:(es_file_t *)file buffer:(char *)buffer size:(size_t)size;
-
-@property(nonatomic, copy) void (^decisionCallback)(santa_message_t);
-@property(nonatomic, copy) void (^logCallback)(santa_message_t);
-@property(readonly, nonatomic) es_client_t *client;
-
-@end

Source/santad/EventProviders/SNTEndpointSecurityManager.mm

@@ -1,645 +0,0 @@
-/// Copyright 2019 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import "Source/santad/EventProviders/SNTEndpointSecurityManager.h"
-
-#include "Source/common/SNTPrefixTree.h"
-
-#import "Source/common/SNTConfigurator.h"
-#import "Source/common/SNTLogging.h"
-#import "Source/common/SantaCache.h"
-
-#include <bsm/libbsm.h>
-#include <libproc.h>
-#include <atomic>
-
-// Gleaned from https://opensource.apple.com/source/xnu/xnu-4903.241.1/bsd/sys/proc_internal.h
-static const pid_t PID_MAX = 99999;
-
-@interface SNTEndpointSecurityManager () {
-  std::atomic<bool> _compilerPIDs[PID_MAX];
-}
-
-@property(nonatomic) SNTPrefixTree *prefixTree;
-@property(nonatomic, readonly) dispatch_queue_t esAuthQueue;
-@property(nonatomic, readonly) dispatch_queue_t esNotifyQueue;
-
-@end
-
-@implementation SNTEndpointSecurityManager
-
-- (instancetype)init API_AVAILABLE(macos(10.15)) {
-  self = [super init];
-  if (self) {
-    // To avoid nil deref from es_events arriving before listenForDecisionRequests or
-    // listenForLogRequests in the  MockEndpointSecurity testing util.
-    _decisionCallback = ^(santa_message_t) {};
-    _logCallback = ^(santa_message_t) {};
-    [self establishClient];
-    [self muteSelf];
-    _prefixTree = new SNTPrefixTree();
-    _esAuthQueue =
-      dispatch_queue_create("com.google.santa.daemon.es_auth", DISPATCH_QUEUE_CONCURRENT);
-    dispatch_set_target_queue(_esAuthQueue,
-                              dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0));
-    _esNotifyQueue =
-      dispatch_queue_create("com.google.santa.daemon.es_notify", DISPATCH_QUEUE_CONCURRENT);
-    dispatch_set_target_queue(_esNotifyQueue, dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0));
-  }
-
-  return self;
-}
-
-- (void)dealloc API_AVAILABLE(macos(10.15)) {
-  if (_client) {
-    es_unsubscribe_all(_client);
-    es_delete_client(_client);
-  }
-  if (_prefixTree) delete _prefixTree;
-}
-
-- (void)muteSelf {
-  audit_token_t myAuditToken;
-  mach_msg_type_number_t count = TASK_AUDIT_TOKEN_COUNT;
-  if (task_info(mach_task_self(), TASK_AUDIT_TOKEN, (task_info_t)&myAuditToken, &count) ==
-        KERN_SUCCESS) {
-    if (es_mute_process(self.client, &myAuditToken) == ES_RETURN_SUCCESS) {
-      return;
-    } else {
-      LOGE(@"Failed to mute this client's process, its events will not be muted.");
-    }
-  } else {
-    LOGE(@"Failed to fetch this client's audit token. Its events will not be muted.");
-  }
-
-  // If we get here, Santa was unable to mute itself. Assume transitory and bail.
-  exit(EXIT_FAILURE);
-}
-
-- (void)establishClient API_AVAILABLE(macos(10.15)) {
-  while (!self.client) {
-    SNTConfigurator *config = [SNTConfigurator configurator];
-
-    es_client_t *client = NULL;
-    es_new_client_result_t ret = es_new_client(&client, ^(es_client_t *c, const es_message_t *m) {
-      pid_t pid = audit_token_to_pid(m->process->audit_token);
-      int pidversion = audit_token_to_pidversion(m->process->audit_token);
-
-      // If enabled, skip any action generated from another endpoint security client.
-      if (m->process->is_es_client && config.ignoreOtherEndpointSecurityClients) {
-        if (m->action_type == ES_ACTION_TYPE_AUTH) {
-          es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, false);
-        }
-
-        return;
-      }
-
-      // Perform the following checks on this serial queue.
-      // Some checks are simple filters that avoid copying m.
-      // However, the bulk of the work done here is to support transitive whitelisting.
-      switch (m->event_type) {
-        case ES_EVENT_TYPE_NOTIFY_EXEC: {
-          // Deny results are currently logged when ES_EVENT_TYPE_AUTH_EXEC posts a deny.
-          // TODO(bur/rah): For ES log denies from NOTIFY messages instead of AUTH.
-          if (m->action.notify.result.auth == ES_AUTH_RESULT_DENY) return;
-
-          // Continue log this event
-          break;
-        }
-        case ES_EVENT_TYPE_NOTIFY_CLOSE: {
-          // Ignore unmodified files
-          if (!m->event.close.modified) return;
-
-          // Remove from decision cache in case this is invalidating a cached binary.
-          [self removeCacheEntryForVnodeID:[self vnodeIDForFile:m->event.close.target]];
-
-          // Create a transitive rule if the file was modified by a running compiler
-          if ([self isCompilerPID:pid]) {
-            santa_message_t sm = {};
-            BOOL truncated =
-              [SNTEndpointSecurityManager populateBufferFromESFile:m->event.close.target
-                                                            buffer:sm.path
-                                                              size:sizeof(sm.path)];
-            if (truncated) {
-              LOGE(@"CLOSE: error creating transitive rule, the path is truncated: path=%s pid=%d",
-                   sm.path, pid);
-              break;
-            }
-            if ([@(sm.path) hasPrefix:@"/dev/"]) {
-              break;
-            }
-            sm.action = ACTION_NOTIFY_WHITELIST;
-            sm.pid = pid;
-            sm.pidversion = pidversion;
-            LOGI(@"CLOSE: creating a transitive rule: path=%s pid=%d", sm.path, sm.pid);
-            self.decisionCallback(sm);
-          }
-
-          // Continue log this event
-          break;
-        }
-        case ES_EVENT_TYPE_NOTIFY_RENAME: {
-          // Create a transitive rule if the file was renamed by a running compiler
-          if ([self isCompilerPID:pid]) {
-            santa_message_t sm = {};
-            BOOL truncated = [self populateRenamedNewPathFromESMessage:m->event.rename
-                                                                buffer:sm.path
-                                                                  size:sizeof(sm.path)];
-            if (truncated) {
-              LOGE(@"RENAME: error creating transitive rule, the path is truncated: path=%s pid=%d",
-                   sm.path, pid);
-              break;
-            }
-            if ([@(sm.path) hasPrefix:@"/dev/"]) {
-              break;
-            }
-            sm.action = ACTION_NOTIFY_WHITELIST;
-            sm.pid = pid;
-            sm.pidversion = pidversion;
-            LOGI(@"RENAME: creating a transitive rule: path=%s pid=%d", sm.path, sm.pid);
-            self.decisionCallback(sm);
-          }
-
-          // Continue log this event
-          break;
-        }
-        case ES_EVENT_TYPE_NOTIFY_EXIT: {
-          // Update the set of running compiler PIDs
-          [self setNotCompilerPID:pid];
-
-          // Skip the standard pipeline and just log.
-          if (![config enableForkAndExitLogging]) return;
-          santa_message_t sm = {};
-          sm.action = ACTION_NOTIFY_EXIT;
-          sm.pid = pid;
-          sm.pidversion = pidversion;
-          sm.ppid = m->process->original_ppid;
-          audit_token_t at = m->process->audit_token;
-          sm.uid = audit_token_to_ruid(at);
-          sm.gid = audit_token_to_rgid(at);
-          dispatch_async(self.esNotifyQueue, ^{
-            self.logCallback(sm);
-          });
-          return;
-        }
-        case ES_EVENT_TYPE_NOTIFY_UNMOUNT: {
-          // Flush the non-root cache - the root disk cannot be unmounted
-          // so it isn't necessary to flush its cache.
-          //
-          // Flushing the cache calls back into ES. We need to perform this off the handler thread
-          // otherwise we could potentially deadlock.
-          dispatch_async(self.esAuthQueue, ^() {
-            [self flushCacheNonRootOnly:YES];
-          });
-
-          // Skip all other processing
-          return;
-        }
-        case ES_EVENT_TYPE_NOTIFY_FORK: {
-          // Skip the standard pipeline and just log.
-          if (![config enableForkAndExitLogging]) return;
-          santa_message_t sm = {};
-          sm.action = ACTION_NOTIFY_FORK;
-          sm.ppid = m->event.fork.child->original_ppid;
-          audit_token_t at = m->event.fork.child->audit_token;
-          sm.pid = audit_token_to_pid(at);
-          sm.pidversion = audit_token_to_pidversion(at);
-          sm.uid = audit_token_to_ruid(at);
-          sm.gid = audit_token_to_rgid(at);
-          dispatch_async(self.esNotifyQueue, ^{
-            self.logCallback(sm);
-          });
-          return;
-        }
-        default: {
-          break;
-        }
-      }
-
-      switch (m->action_type) {
-        case ES_ACTION_TYPE_AUTH: {
-          // Copy the message
-          es_message_t *mc = es_copy_message(m);
-
-          dispatch_semaphore_t processingSema = dispatch_semaphore_create(0);
-          // Add 1 to the processing semaphore. We're not creating it with a starting
-          // value of 1 because that requires that the semaphore is not deallocated
-          // until its value matches the starting value, which we don't need.
-          dispatch_semaphore_signal(processingSema);
-          dispatch_semaphore_t deadlineExpiredSema = dispatch_semaphore_create(0);
-
-          // Create a timer to deny the execution 5 seconds before the deadline,
-          // if a response hasn't already been sent. This block will still be enqueued if
-          // the the deadline - 5 secs is < DISPATCH_TIME_NOW.
-          // As of 10.15.5, a typical deadline is 60 seconds.
-          dispatch_after(dispatch_time(m->deadline, NSEC_PER_SEC * -5), self.esAuthQueue, ^(void) {
-            if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
-              // Handler has already responded, nothing to do.
-              return;
-            }
-            LOGE(@"SNTEndpointSecurityManager: deadline reached: deny pid=%d ret=%d", pid,
-                 es_respond_auth_result(self.client, mc, ES_AUTH_RESULT_DENY, false));
-            dispatch_semaphore_signal(deadlineExpiredSema);
-          });
-
-          // Dispatch off to the handler and return control to ES.
-          dispatch_async(self.esAuthQueue, ^{
-            [self messageHandler:mc];
-            if (dispatch_semaphore_wait(processingSema, DISPATCH_TIME_NOW) != 0) {
-              // Deadline expired, wait for deadline block to finish.
-              dispatch_semaphore_wait(deadlineExpiredSema, DISPATCH_TIME_FOREVER);
-            }
-            es_free_message(mc);
-          });
-          break;
-        }
-        case ES_ACTION_TYPE_NOTIFY: {
-          // Copy the message and return control back to ES
-          es_message_t *mc = es_copy_message(m);
-          dispatch_async(self.esNotifyQueue, ^{
-            [self messageHandler:mc];
-            es_free_message(mc);
-          });
-          break;
-        }
-        default: {
-          break;
-        }
-      }
-    });
-
-    switch (ret) {
-      case ES_NEW_CLIENT_RESULT_SUCCESS:
-        LOGI(@"Connected to EndpointSecurity");
-        _client = client;
-        return;
-      case ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED:
-        LOGE(@"Unable to create EndpointSecurity client, not full-disk access permitted");
-        LOGE(@"Sleeping for 30s before restarting.");
-        sleep(30);
-        exit(ret);
-      default:
-        LOGE(@"Unable to create es client: %d. Sleeping for a minute.", ret);
-        sleep(60);
-        continue;
-    }
-  }
-}
-
-- (BOOL)respondFromCache:(es_message_t *)m API_AVAILABLE(macos(10.15)) {
-  return NO;
-}
-
-- (void)messageHandler:(es_message_t *)m API_AVAILABLE(macos(10.15)) {
-  santa_message_t sm = {};
-  sm.es_message = (void *)m;
-
-  es_process_t *targetProcess = NULL;
-  es_file_t *targetFile = NULL;
-  void (^callback)(santa_message_t);
-
-  switch (m->event_type) {
-    case ES_EVENT_TYPE_AUTH_EXEC: {
-      if ([self respondFromCache:m]) {
-        return;
-      }
-
-      sm.action = ACTION_REQUEST_BINARY;
-      targetFile = m->event.exec.target->executable;
-      targetProcess = m->event.exec.target;
-      callback = self.decisionCallback;
-
-      [SNTEndpointSecurityManager populateBufferFromESFile:m->process->tty
-                                                    buffer:sm.ttypath
-                                                      size:sizeof(sm.ttypath)];
-      break;
-    }
-    case ES_EVENT_TYPE_NOTIFY_EXEC: {
-      sm.action = ACTION_NOTIFY_EXEC;
-      targetFile = m->event.exec.target->executable;
-      targetProcess = m->event.exec.target;
-
-      // TODO(rah): Profile this, it might need to be improved.
-      uint32_t argCount = es_exec_arg_count(&(m->event.exec));
-      NSMutableArray *args = [NSMutableArray arrayWithCapacity:argCount];
-      for (int i = 0; i < argCount; ++i) {
-        es_string_token_t arg = es_exec_arg(&(m->event.exec), i);
-        NSString *argStr = [[NSString alloc] initWithBytes:arg.data
-                                                    length:arg.length
-                                                  encoding:NSUTF8StringEncoding];
-        if (argStr.length) [args addObject:argStr];
-      }
-      sm.args_array = (void *)CFBridgingRetain(args);
-      callback = self.logCallback;
-      break;
-    }
-    case ES_EVENT_TYPE_AUTH_UNLINK: {
-      es_string_token_t pathToken = m->event.unlink.target->path;
-      NSString *path = [[NSString alloc] initWithBytes:pathToken.data
-                                                length:pathToken.length
-                                              encoding:NSUTF8StringEncoding];
-      if ([self isDatabasePath:path]) {
-        LOGW(@"Preventing attempt to delete Santa databases!");
-        es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, true);
-        return;
-      }
-      es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, true);
-      return;
-    }
-    case ES_EVENT_TYPE_AUTH_RENAME: {
-      es_string_token_t pathToken = m->event.rename.source->path;
-      NSString *path = [[NSString alloc] initWithBytes:pathToken.data
-                                                length:pathToken.length
-                                              encoding:NSUTF8StringEncoding];
-
-      if ([self isDatabasePath:path]) {
-        LOGW(@"Preventing attempt to rename Santa databases!");
-        es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, true);
-        return;
-      }
-      if (m->event.rename.destination_type == ES_DESTINATION_TYPE_EXISTING_FILE) {
-        es_string_token_t destToken = m->event.rename.destination.existing_file->path;
-        NSString *destPath = [[NSString alloc] initWithBytes:destToken.data
-                                                      length:destToken.length
-                                                    encoding:NSUTF8StringEncoding];
-        if ([self isDatabasePath:destPath]) {
-          LOGW(@"Preventing attempt to overwrite Santa databases!");
-          es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, true);
-          return;
-        }
-      }
-      es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, true);
-      return;
-    }
-    case ES_EVENT_TYPE_AUTH_KEXTLOAD: {
-      es_string_token_t identifier = m->event.kextload.identifier;
-      NSString *ident = [[NSString alloc] initWithBytes:identifier.data
-                                                 length:identifier.length
-                                               encoding:NSUTF8StringEncoding];
-      if ([ident isEqualToString:@"com.google.santa-driver"]) {
-        LOGW(@"Preventing attempt to load Santa kext!");
-        es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, true);
-        return;
-      }
-      es_respond_auth_result(self.client, m, ES_AUTH_RESULT_ALLOW, true);
-      return;
-    }
-
-    case ES_EVENT_TYPE_NOTIFY_CLOSE: {
-      sm.action = ACTION_NOTIFY_WRITE;
-      targetFile = m->event.close.target;
-      targetProcess = m->process;
-      callback = self.logCallback;
-      break;
-    }
-    case ES_EVENT_TYPE_NOTIFY_UNLINK: {
-      sm.action = ACTION_NOTIFY_DELETE;
-      targetFile = m->event.unlink.target;
-      targetProcess = m->process;
-      callback = self.logCallback;
-      break;
-    }
-    case ES_EVENT_TYPE_NOTIFY_LINK: {
-      sm.action = ACTION_NOTIFY_LINK;
-      targetFile = m->event.link.source;
-      targetProcess = m->process;
-      NSString *p = @(m->event.link.target_dir->path.data);
-      p = [p stringByAppendingPathComponent:@(m->event.link.target_filename.data)];
-      [SNTEndpointSecurityManager populateBufferFromString:p.UTF8String
-                                                    buffer:sm.newpath
-                                                      size:sizeof(sm.newpath)];
-      callback = self.logCallback;
-      break;
-    }
-    case ES_EVENT_TYPE_NOTIFY_RENAME: {
-      sm.action = ACTION_NOTIFY_RENAME;
-      targetFile = m->event.rename.source;
-      targetProcess = m->process;
-      [self populateRenamedNewPathFromESMessage:m->event.rename
-                                         buffer:sm.newpath
-                                           size:sizeof(sm.newpath)];
-      callback = self.logCallback;
-      break;
-    }
-    default: LOGE(@"Unknown es message: %d", m->event_type); return;
-  }
-
-  // Deny auth exec events if the path doesn't fit in the santa message.
-  // TODO(bur/rah): Add support for larger paths.
-  if ([SNTEndpointSecurityManager populateBufferFromESFile:targetFile
-                                                    buffer:sm.path
-                                                      size:sizeof(sm.path)] &&
-      m->event_type == ES_EVENT_TYPE_AUTH_EXEC) {
-    LOGE(@"path is truncated, deny: %s", sm.path);
-    es_respond_auth_result(self.client, m, ES_AUTH_RESULT_DENY, false);
-    return;
-  }
-
-  // Filter file op events matching the prefix tree.
-  if (!(m->event_type == ES_EVENT_TYPE_AUTH_EXEC || m->event_type == ES_EVENT_TYPE_NOTIFY_EXEC) &&
-      self.prefixTree->HasPrefix(sm.path)) {
-    return;
-  }
-
-  sm.vnode_id.fsid = targetFile->stat.st_dev;
-  sm.vnode_id.fileid = targetFile->stat.st_ino;
-  sm.uid = audit_token_to_ruid(targetProcess->audit_token);
-  sm.gid = audit_token_to_rgid(targetProcess->audit_token);
-  sm.pid = audit_token_to_pid(targetProcess->audit_token);
-  sm.pidversion = audit_token_to_pidversion(targetProcess->audit_token);
-  sm.ppid = targetProcess->original_ppid;
-  proc_name((m->event_type == ES_EVENT_TYPE_AUTH_EXEC) ? sm.ppid : sm.pid, sm.pname, 1024);
-  callback(sm);
-  if (sm.args_array) {
-    CFBridgingRelease(sm.args_array);
-  }
-}
-
-- (void)listenForDecisionRequests:(void (^)(santa_message_t))callback API_AVAILABLE(macos(10.15)) {
-  while (!self.connectionEstablished)
-    usleep(100000);  // 100ms
-
-  self.decisionCallback = callback;
-  es_event_type_t events[] = {
-    ES_EVENT_TYPE_AUTH_EXEC,
-    ES_EVENT_TYPE_AUTH_UNLINK,
-    ES_EVENT_TYPE_AUTH_RENAME,
-    ES_EVENT_TYPE_AUTH_KEXTLOAD,
-
-    // This is in the decision callback because it's used for detecting
-    // the exit of a 'compiler' used by transitive whitelisting.
-    ES_EVENT_TYPE_NOTIFY_EXIT,
-
-    // This is in the decision callback because it's used for clearing the
-    // caches when a disk is unmounted.
-    ES_EVENT_TYPE_NOTIFY_UNMOUNT,
-  };
-  es_return_t sret = es_subscribe(self.client, events, sizeof(events) / sizeof(es_event_type_t));
-  if (sret != ES_RETURN_SUCCESS) LOGE(@"Unable to subscribe to auth events: %d", sret);
-
-  // There's a gap between creating a client and subscribing to events. Creating the client
-  // triggers a cache flush automatically but any events that happen in this gap could be allowed
-  // and cached, so we force the cache to flush again.
-  [self flushCacheNonRootOnly:NO];
-}
-
-- (void)listenForLogRequests:(void (^)(santa_message_t))callback API_AVAILABLE(macos(10.15)) {
-  while (!self.connectionEstablished)
-    usleep(100000);  // 100ms
-
-  self.logCallback = callback;
-  es_event_type_t events[] = {
-    ES_EVENT_TYPE_NOTIFY_EXEC,   ES_EVENT_TYPE_NOTIFY_CLOSE,  ES_EVENT_TYPE_NOTIFY_LINK,
-    ES_EVENT_TYPE_NOTIFY_RENAME, ES_EVENT_TYPE_NOTIFY_UNLINK, ES_EVENT_TYPE_NOTIFY_FORK,
-  };
-  es_return_t sret = es_subscribe(self.client, events, sizeof(events) / sizeof(es_event_type_t));
-  if (sret != ES_RETURN_SUCCESS) LOGE(@"Unable to subscribe to notify events: %d", sret);
-}
-
-- (int)postAction:(santa_action_t)action
-       forMessage:(santa_message_t)sm API_AVAILABLE(macos(10.15)) {
-  es_respond_result_t ret;
-  switch (action) {
-    case ACTION_RESPOND_ALLOW_COMPILER:
-      [self setIsCompilerPID:sm.pid];
-
-      // Allow the exec, but don't cache the decision so subsequent execs of the compiler get
-      // marked appropriately.
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_ALLOW,
-                                   false);
-      break;
-    case ACTION_RESPOND_ALLOW:
-    case ACTION_RESPOND_ALLOW_PENDING_TRANSITIVE:
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_ALLOW,
-                                   true);
-      break;
-    case ACTION_RESPOND_DENY:
-    case ACTION_RESPOND_TOOLONG:
-      ret = es_respond_auth_result(self.client, (es_message_t *)sm.es_message, ES_AUTH_RESULT_DENY,
-                                   false);
-      break;
-    case ACTION_RESPOND_ACK: return ES_RESPOND_RESULT_SUCCESS;
-    default: ret = ES_RESPOND_RESULT_ERR_INVALID_ARGUMENT;
-  }
-
-  return ret;
-}
-
-- (BOOL)flushCacheNonRootOnly:(BOOL)nonRootOnly API_AVAILABLE(macos(10.15)) {
-  if (!self.connectionEstablished) return YES;  // if not connected, there's nothing to flush.
-  return es_clear_cache(self.client) == ES_CLEAR_CACHE_RESULT_SUCCESS;
-}
-
-- (void)fileModificationPrefixFilterAdd:(NSArray *)filters {
-  for (NSString *filter in filters) {
-    self.prefixTree->AddPrefix(filter.fileSystemRepresentation);
-  }
-}
-
-- (void)fileModificationPrefixFilterReset {
-  self.prefixTree->Reset();
-}
-
-- (NSArray<NSNumber *> *)cacheCounts {
-  return nil;
-}
-
-- (NSArray<NSNumber *> *)cacheBucketCount {
-  return nil;
-}
-
-- (santa_action_t)checkCache:(santa_vnode_id_t)vnodeID {
-  return ACTION_UNSET;
-}
-
-- (kern_return_t)removeCacheEntryForVnodeID:(santa_vnode_id_t)vnodeId {
-  return KERN_FAILURE;
-}
-
-- (BOOL)connectionEstablished {
-  return self.client != nil;
-}
-
-#pragma mark helpers
-
-// Returns YES if the path was truncated.
-// The populated buffer will be NUL terminated.
-+ (BOOL)populateBufferFromESFile:(es_file_t *)file buffer:(char *)buffer size:(size_t)size {
-  if (file == NULL) return NO;
-  return [SNTEndpointSecurityManager populateBufferFromString:file->path.data
-                                                       buffer:buffer
-                                                         size:size];
-}
-
-// Returns YES if the path was truncated.
-// The populated buffer will be NUL terminated.
-+ (BOOL)populateBufferFromString:(const char *)string buffer:(char *)buffer size:(size_t)size {
-  return strlcpy(buffer, string, size) >= size;
-}
-
-- (BOOL)populateRenamedNewPathFromESMessage:(es_event_rename_t)mv
-                                     buffer:(char *)buffer
-                                       size:(size_t)size {
-  BOOL truncated = NO;
-  switch (mv.destination_type) {
-    case ES_DESTINATION_TYPE_NEW_PATH: {
-      NSString *p = @(mv.destination.new_path.dir->path.data);
-      p = [p stringByAppendingPathComponent:@(mv.destination.new_path.filename.data)];
-      truncated = [SNTEndpointSecurityManager populateBufferFromString:p.UTF8String
-                                                                buffer:buffer
-                                                                  size:size];
-      break;
-    }
-    case ES_DESTINATION_TYPE_EXISTING_FILE: {
-      truncated = [SNTEndpointSecurityManager populateBufferFromESFile:mv.destination.existing_file
-                                                                buffer:buffer
-                                                                  size:size];
-      break;
-    }
-  }
-  return truncated;
-}
-
-- (santa_vnode_id_t)vnodeIDForFile:(es_file_t *)file {
-  return {
-    .fsid = (uint64_t)file->stat.st_dev,
-    .fileid = file->stat.st_ino,
-  };
-}
-
-- (BOOL)isDatabasePath:(NSString *)path {
-  return [path isEqualToString:@"/private/var/db/santa/rules.db"] ||
-         [path isEqualToString:@"/private/var/db/santa/events.db"];
-}
-
-- (BOOL)isCompilerPID:(pid_t)pid {
-  return (pid && pid < PID_MAX && self->_compilerPIDs[pid].load());
-}
-
-- (void)setIsCompilerPID:(pid_t)pid {
-  if (pid < 1) {
-    LOGE(@"Unable to watch compiler pid=%d", pid);
-  } else if (pid >= PID_MAX) {
-    LOGE(@"Unable to watch compiler pid=%d >= PID_MAX(%d)", pid, PID_MAX);
-  } else {
-    self->_compilerPIDs[pid].store(true);
-    LOGD(@"Watching compiler pid=%d", pid);
-  }
-}
-
-- (void)setNotCompilerPID:(pid_t)pid {
-  if (pid && pid < PID_MAX) self->_compilerPIDs[pid].store(false);
-}
-
-@end

Source/santad/EventProviders/SNTEndpointSecurityManagerTest.mm

@@ -1,250 +0,0 @@
-/// Copyright 2021 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-#import <XCTest/XCTest.h>
-#import <bsm/libbsm.h>
-
-#import "Source/common/SNTConfigurator.h"
-#import "Source/santad/EventProviders/SNTEndpointSecurityManager.h"
-
-// Must be imported last to overload libEndpointSecurity functions.
-#import "Source/santad/EventProviders/EndpointSecurityTestUtil.h"
-
-const NSString *const kEventsDBPath = @"/private/var/db/santa/events.db";
-const NSString *const kRulesDBPath = @"/private/var/db/santa/rules.db";
-const NSString *const kBenignPath = @"/some/other/path";
-
-@interface SNTEndpointSecurityManagerTest : XCTestCase
-@end
-
-@implementation SNTEndpointSecurityManagerTest
-
-- (void)setUp {
-  [super setUp];
-  fclose(stdout);
-}
-
-- (void)testDenyOnTimeout {
-  // There should be two events: an early uncached DENY as the consequence for not
-  // meeting the decision deadline and an actual cached decision from our message
-  // handler.
-  __block int wantNumResp = 2;
-
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-  SNTEndpointSecurityManager *snt = [[SNTEndpointSecurityManager alloc] init];
-  (void)snt;  // Make it appear used for the sake of -Wunused-variable
-
-  XCTestExpectation *expectation =
-    [self expectationWithDescription:@"Wait for santa's Auth dispatch queue"];
-
-  __block NSMutableArray<ESResponse *> *events = [NSMutableArray array];
-  [mockES registerResponseCallback:ES_EVENT_TYPE_AUTH_UNLINK
-                      withCallback:^(ESResponse *r) {
-                        @synchronized(self) {
-                          [events addObject:r];
-                        }
-
-                        if (events.count >= wantNumResp) {
-                          [expectation fulfill];
-                        }
-                      }];
-
-  __block es_file_t dbFile = {.path = MakeStringToken(kEventsDBPath)};
-  ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-    m.binaryPath = @"somebinary";
-    m.message->action_type = ES_ACTION_TYPE_AUTH;
-    m.message->event_type = ES_EVENT_TYPE_AUTH_UNLINK;
-    m.message->event = (es_events_t){.unlink = {.target = &dbFile}};
-    m.message->mach_time = 1234;
-    m.message->deadline = 1234;
-  }];
-
-  [mockES triggerHandler:m.message];
-
-  [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-  for (ESResponse *resp in events) {
-    XCTAssertEqual(
-      resp.result, ES_AUTH_RESULT_DENY,
-      @"Failed to automatically deny on timeout and also the malicious event afterwards");
-  }
-}
-
-- (void)testDeleteRulesDB {
-  NSDictionary<const NSString *, NSNumber *> *testCases = @{
-    kEventsDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kRulesDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kBenignPath : [NSNumber numberWithInt:ES_AUTH_RESULT_ALLOW],
-  };
-  for (const NSString *testPath in testCases) {
-    MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-    [mockES reset];
-    SNTEndpointSecurityManager *snt = [[SNTEndpointSecurityManager alloc] init];
-    (void)snt;  // Make it appear used for the sake of -Wunused-variable
-
-    XCTestExpectation *expectation = [self expectationWithDescription:@"Wait for response from ES"];
-    __block ESResponse *got;
-    [mockES registerResponseCallback:ES_EVENT_TYPE_AUTH_UNLINK
-                        withCallback:^(ESResponse *r) {
-                          got = r;
-                          [expectation fulfill];
-                        }];
-
-    __block es_file_t dbFile = {.path = MakeStringToken(testPath)};
-    ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-      m.binaryPath = @"somebinary";
-      m.message->action_type = ES_ACTION_TYPE_AUTH;
-      m.message->event_type = ES_EVENT_TYPE_AUTH_UNLINK;
-      m.message->event = (es_events_t){.unlink = {.target = &dbFile}};
-    }];
-
-    [mockES triggerHandler:m.message];
-
-    [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-    XCTAssertEqual(got.result, [testCases objectForKey:testPath].intValue,
-                   @"Incorrect handling of delete of %@", testPath);
-    XCTAssertTrue(got.shouldCache, @"Failed to cache deletion decision of %@", testPath);
-  }
-}
-
-- (void)testSkipOtherESEvents {
-  MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-  [mockES reset];
-  SNTEndpointSecurityManager *snt = [[SNTEndpointSecurityManager alloc] init];
-  (void)snt;  // Make it appear used for the sake of -Wunused-variable
-
-  XCTestExpectation *expectation = [self expectationWithDescription:@"Wait for response from ES"];
-  __block ESResponse *got;
-  [mockES registerResponseCallback:ES_EVENT_TYPE_AUTH_UNLINK
-                      withCallback:^(ESResponse *r) {
-                        got = r;
-                        [expectation fulfill];
-                      }];
-
-  __block es_file_t dbFile = {.path = MakeStringToken(@"/some/other/path")};
-  ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-    m.process->is_es_client = true;
-    m.binaryPath = @"somebinary";
-    m.message->action_type = ES_ACTION_TYPE_AUTH;
-    m.message->event_type = ES_EVENT_TYPE_AUTH_UNLINK;
-    m.message->event = (es_events_t){.unlink = {.target = &dbFile}};
-  }];
-
-  [mockES triggerHandler:m.message];
-
-  [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-  XCTAssertEqual(got.result, ES_AUTH_RESULT_ALLOW);
-}
-
-- (void)testRenameOverwriteRulesDB {
-  NSDictionary<const NSString *, NSNumber *> *testCases = @{
-    kEventsDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kRulesDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kBenignPath : [NSNumber numberWithInt:ES_AUTH_RESULT_ALLOW],
-  };
-  for (const NSString *testPath in testCases) {
-    MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-    [mockES reset];
-    SNTEndpointSecurityManager *snt = [[SNTEndpointSecurityManager alloc] init];
-    (void)snt;  // Make it appear used for the sake of -Wunused-variable
-
-    XCTestExpectation *expectation = [self expectationWithDescription:@"Wait for response from ES"];
-    __block ESResponse *got;
-    [mockES registerResponseCallback:ES_EVENT_TYPE_AUTH_RENAME
-                        withCallback:^(ESResponse *r) {
-                          got = r;
-                          [expectation fulfill];
-                        }];
-
-    __block es_file_t otherFile = {.path = MakeStringToken(@"/some/other/path")};
-    __block es_file_t dbFile = {.path = MakeStringToken(testPath)};
-    ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-      m.binaryPath = @"somebinary";
-      m.message->action_type = ES_ACTION_TYPE_AUTH;
-      m.message->event_type = ES_EVENT_TYPE_AUTH_RENAME;
-      m.message->event = (es_events_t){
-        .rename =
-          {
-            .source = &otherFile,
-            .destination_type = ES_DESTINATION_TYPE_EXISTING_FILE,
-            .destination = {.existing_file = &dbFile},
-          },
-      };
-    }];
-
-    [mockES triggerHandler:m.message];
-
-    [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-    XCTAssertEqual(got.result, [testCases objectForKey:testPath].intValue,
-                   @"Incorrect handling of rename of %@", testPath);
-    XCTAssertTrue(got.shouldCache, @"Failed to cache rename auth decision of %@", testPath);
-  }
-}
-
-- (void)testRenameRulesDB {
-  NSDictionary<const NSString *, NSNumber *> *testCases = @{
-    kEventsDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kRulesDBPath : [NSNumber numberWithInt:ES_AUTH_RESULT_DENY],
-    kBenignPath : [NSNumber numberWithInt:ES_AUTH_RESULT_ALLOW],
-  };
-
-  for (const NSString *testPath in testCases) {
-    MockEndpointSecurity *mockES = [MockEndpointSecurity mockEndpointSecurity];
-    [mockES reset];
-    SNTEndpointSecurityManager *snt = [[SNTEndpointSecurityManager alloc] init];
-    (void)snt;  // Make it appear used for the sake of -Wunused-variable
-
-    XCTestExpectation *expectation = [self expectationWithDescription:@"Wait for response from ES"];
-    __block ESResponse *got;
-    [mockES registerResponseCallback:ES_EVENT_TYPE_AUTH_RENAME
-                        withCallback:^(ESResponse *r) {
-                          got = r;
-                          [expectation fulfill];
-                        }];
-
-    __block es_file_t otherFile = {.path = MakeStringToken(@"/some/other/path")};
-    __block es_file_t dbFile = {.path = MakeStringToken(testPath)};
-    ESMessage *m = [[ESMessage alloc] initWithBlock:^(ESMessage *m) {
-      m.binaryPath = @"somebinary";
-      m.message->action_type = ES_ACTION_TYPE_AUTH;
-      m.message->event_type = ES_EVENT_TYPE_AUTH_RENAME;
-      m.message->event = (es_events_t){
-        .rename =
-          {
-            .source = &dbFile,
-            .destination_type = ES_DESTINATION_TYPE_NEW_PATH,
-            .destination = {.new_path =
-                              {
-                                .dir = &otherFile,
-                                .filename = MakeStringToken(@"someotherfilename"),
-                              }},
-          },
-      };
-    }];
-
-    [mockES triggerHandler:m.message];
-
-    [self waitForExpectations:@[ expectation ] timeout:60.0];
-
-    XCTAssertEqual(got.result, [testCases objectForKey:testPath].intValue,
-                   @"Incorrect handling of rename of %@", testPath);
-
-    XCTAssertTrue(got.shouldCache, @"Failed to cache rename auth decision of %@", testPath);
-  }
-}
-
-@end

Source/santad/EventProviders/SNTEndpointSecurityRecorder.h

@@ -0,0 +1,40 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/common/SNTPrefixTree.h"
+#import "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityEventHandler.h"
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
+#import "Source/santad/SNTCompilerController.h"
+
+/// ES Client focused on subscribing to NOTIFY event variants with the intention of enriching
+/// received messages and logging the information.
+@interface SNTEndpointSecurityRecorder : SNTEndpointSecurityClient <SNTEndpointSecurityEventHandler>
+
+- (instancetype)
+       initWithESAPI:
+         (std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI>)
+           esApi
+              logger:(std::shared_ptr<santa::santad::logs::endpoint_security::Logger>)logger
+            enricher:
+              (std::shared_ptr<santa::santad::event_providers::endpoint_security::Enricher>)enricher
+  compilerController:(SNTCompilerController *)compilerController
+     authResultCache:
+       (std::shared_ptr<santa::santad::event_providers::AuthResultCache>)authResultCache
+          prefixTree:(std::shared_ptr<SNTPrefixTree>)prefixTree;
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityRecorder.mm

@@ -0,0 +1,119 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/santad/EventProviders/SNTEndpointSecurityRecorder.h"
+
+#include <EndpointSecurity/ESTypes.h>
+
+#import "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::Enricher;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::Logger;
+
+es_file_t *GetTargetFileForPrefixTree(const es_message_t *msg) {
+  switch (msg->event_type) {
+    case ES_EVENT_TYPE_NOTIFY_CLOSE: return msg->event.close.target;
+    case ES_EVENT_TYPE_NOTIFY_LINK: return msg->event.link.source;
+    case ES_EVENT_TYPE_NOTIFY_RENAME: return msg->event.rename.source;
+    case ES_EVENT_TYPE_NOTIFY_UNLINK: return msg->event.unlink.target;
+    default: return NULL;
+  }
+}
+
+@interface SNTEndpointSecurityRecorder ()
+@property SNTCompilerController *compilerController;
+@end
+
+@implementation SNTEndpointSecurityRecorder {
+  std::shared_ptr<AuthResultCache> _authResultCache;
+  std::shared_ptr<Enricher> _enricher;
+  std::shared_ptr<Logger> _logger;
+  std::shared_ptr<SNTPrefixTree> _prefixTree;
+}
+
+- (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi
+                       logger:(std::shared_ptr<Logger>)logger
+                     enricher:(std::shared_ptr<Enricher>)enricher
+           compilerController:(SNTCompilerController *)compilerController
+              authResultCache:(std::shared_ptr<AuthResultCache>)authResultCache
+                   prefixTree:(std::shared_ptr<SNTPrefixTree>)prefixTree {
+  self = [super initWithESAPI:std::move(esApi)];
+  if (self) {
+    _enricher = enricher;
+    _logger = logger;
+    _compilerController = compilerController;
+    _authResultCache = authResultCache;
+    _prefixTree = prefixTree;
+
+    [self establishClientOrDie];
+  }
+  return self;
+}
+
+- (void)handleMessage:(Message &&)esMsg {
+  // Pre-enrichment processing
+  switch (esMsg->event_type) {
+    case ES_EVENT_TYPE_NOTIFY_CLOSE:
+      // TODO(mlw): Once we move to building with the macOS 13 SDK, we should also check
+      // the `was_mapped_writable` field
+      if (esMsg->event.close.modified == false) {
+        // Ignore unmodified files
+        return;
+      }
+
+      self->_authResultCache->RemoveFromCache(esMsg->event.close.target);
+      break;
+    default: break;
+  }
+
+  [self.compilerController handleEvent:esMsg withLogger:self->_logger];
+
+  // Filter file op events matching the prefix tree.
+  es_file_t *targetFile = GetTargetFileForPrefixTree(&(*esMsg));
+  if (targetFile != NULL && self->_prefixTree->HasPrefix(targetFile->path.data)) {
+    return;
+  }
+
+  // Enrich the message inline with the ES handler block to capture enrichment
+  // data as close to the source event as possible.
+  std::shared_ptr<EnrichedMessage> sharedEnrichedMessage = _enricher->Enrich(std::move(esMsg));
+
+  // Asynchronously log the message
+  [self processEnrichedMessage:std::move(sharedEnrichedMessage)
+                       handler:^(std::shared_ptr<EnrichedMessage> msg) {
+                         self->_logger->Log(std::move(msg));
+                       }];
+}
+
+- (void)enable {
+  [super subscribe:{
+                     ES_EVENT_TYPE_NOTIFY_CLOSE,
+                     ES_EVENT_TYPE_NOTIFY_EXCHANGEDATA,
+                     ES_EVENT_TYPE_NOTIFY_EXEC,
+                     ES_EVENT_TYPE_NOTIFY_FORK,
+                     ES_EVENT_TYPE_NOTIFY_EXIT,
+                     ES_EVENT_TYPE_NOTIFY_LINK,
+                     ES_EVENT_TYPE_NOTIFY_RENAME,
+                     ES_EVENT_TYPE_NOTIFY_UNLINK,
+                   }];
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityRecorderTest.mm

@@ -0,0 +1,211 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/ESTypes.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <cstddef>
+
+#include <memory>
+#include <set>
+
+#include "Source/common/TestUtils.h"
+#import "Source/santad/EventProviders/AuthResultCache.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityRecorder.h"
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
+#import "Source/santad/SNTCompilerController.h"
+
+using santa::santad::event_providers::AuthResultCache;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::Enricher;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::Logger;
+
+class MockEnricher : public Enricher {
+ public:
+  MOCK_METHOD(std::shared_ptr<EnrichedMessage>, Enrich, (Message &&));
+};
+
+class MockAuthResultCache : public AuthResultCache {
+ public:
+  using AuthResultCache::AuthResultCache;
+
+  MOCK_METHOD(void, RemoveFromCache, (const es_file_t *));
+};
+
+class MockLogger : public Logger {
+ public:
+  using Logger::Logger;
+
+  MOCK_METHOD(void, Log, (std::shared_ptr<EnrichedMessage>));
+};
+
+@interface SNTEndpointSecurityRecorderTest : XCTestCase
+@end
+
+@implementation SNTEndpointSecurityRecorderTest
+
+- (void)testEnable {
+  // Ensure the client subscribes to expected event types
+  std::set<es_event_type_t> expectedEventSubs{
+    ES_EVENT_TYPE_NOTIFY_CLOSE,  ES_EVENT_TYPE_NOTIFY_EXCHANGEDATA, ES_EVENT_TYPE_NOTIFY_EXEC,
+    ES_EVENT_TYPE_NOTIFY_FORK,   ES_EVENT_TYPE_NOTIFY_EXIT,         ES_EVENT_TYPE_NOTIFY_LINK,
+    ES_EVENT_TYPE_NOTIFY_RENAME, ES_EVENT_TYPE_NOTIFY_UNLINK,
+  };
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  id recorderClient = [[SNTEndpointSecurityRecorder alloc] initWithESAPI:mockESApi];
+
+  EXPECT_CALL(*mockESApi, Subscribe(testing::_, expectedEventSubs)).WillOnce(testing::Return(true));
+
+  [recorderClient enable];
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+}
+
+- (void)testHandleMessage {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_CLOSE, &proc, ActionType::Auth);
+  es_file_t targetFile = MakeESFile("bar");
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  std::shared_ptr<EnrichedMessage> enrichedMsg = std::shared_ptr<EnrichedMessage>(nullptr);
+
+  auto mockEnricher = std::make_shared<MockEnricher>();
+  EXPECT_CALL(*mockEnricher, Enrich).WillOnce(testing::Return(enrichedMsg));
+
+  auto mockAuthCache = std::make_shared<MockAuthResultCache>(nullptr);
+  EXPECT_CALL(*mockAuthCache, RemoveFromCache(&targetFile)).Times(1);
+
+  // NOTE: Currently unable to create a partial mock of the
+  // `SNTEndpointSecurityRecorder` object. There is a bug in OCMock that doesn't
+  // properly handle the `processEnrichedMessage:handler:` block. Instead this
+  // test will mock the `Log` method that is called in the handler block.
+  dispatch_semaphore_t sema = dispatch_semaphore_create(0);
+  auto mockLogger = std::make_shared<MockLogger>(nullptr, nullptr);
+  EXPECT_CALL(*mockLogger, Log).WillOnce(testing::InvokeWithoutArgs(^() {
+    dispatch_semaphore_signal(sema);
+  }));
+
+  auto prefixTree = std::make_shared<SNTPrefixTree>();
+
+  id mockCC = OCMStrictClassMock([SNTCompilerController class]);
+
+  SNTEndpointSecurityRecorder *recorderClient =
+    [[SNTEndpointSecurityRecorder alloc] initWithESAPI:mockESApi
+                                                logger:mockLogger
+                                              enricher:mockEnricher
+                                    compilerController:mockCC
+                                       authResultCache:mockAuthCache
+                                            prefixTree:prefixTree];
+
+  // CLOSE not modified, bail early
+  {
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_CLOSE;
+    esMsg.event.close.modified = false;
+    esMsg.event.close.target = NULL;
+
+    XCTAssertNoThrow([recorderClient handleMessage:Message(mockESApi, &esMsg)]);
+  }
+
+  // CLOSE modified, remove from cache
+  {
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_CLOSE;
+    esMsg.event.close.modified = true;
+    esMsg.event.close.target = &targetFile;
+    Message msg(mockESApi, &esMsg);
+
+    OCMExpect([mockCC handleEvent:msg withLogger:nullptr]).ignoringNonObjectArgs();
+
+    [recorderClient handleMessage:std::move(msg)];
+
+    XCTAssertEqual(
+      0, dispatch_semaphore_wait(sema, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC)),
+      "Log wasn't called within expected time window");
+  }
+
+  // LINK, Prefix match, bail early
+  {
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_LINK;
+    esMsg.event.link.source = &targetFile;
+    prefixTree->AddPrefix(esMsg.event.link.source->path.data);
+    Message msg(mockESApi, &esMsg);
+
+    OCMExpect([mockCC handleEvent:msg withLogger:nullptr]).ignoringNonObjectArgs();
+
+    [recorderClient handleMessage:std::move(msg)];
+  }
+
+  XCTAssertTrue(OCMVerifyAll(mockCC));
+
+  XCTBubbleMockVerifyAndClearExpectations(mockAuthCache.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockEnricher.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockLogger.get());
+
+  [mockCC stopMocking];
+}
+
+- (void)testGetTargetFileForPrefixTree {
+  // Ensure `GetTargetFileForPrefixTree` returns expected field for each
+  // subscribed event type in the `SNTEndpointSecurityRecorder`.
+  extern es_file_t *GetTargetFileForPrefixTree(const es_message_t *msg);
+
+  es_file_t closeFile = MakeESFile("close");
+  es_file_t linkFile = MakeESFile("link");
+  es_file_t renameFile = MakeESFile("rename");
+  es_file_t unlinkFile = MakeESFile("unlink");
+  es_message_t esMsg;
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_CLOSE;
+  esMsg.event.close.target = &closeFile;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), &closeFile);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_LINK;
+  esMsg.event.link.source = &linkFile;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), &linkFile);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_RENAME;
+  esMsg.event.rename.source = &renameFile;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), &renameFile);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_UNLINK;
+  esMsg.event.unlink.target = &unlinkFile;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), &unlinkFile);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_EXCHANGEDATA;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), nullptr);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_EXEC;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), nullptr);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_FORK;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), nullptr);
+
+  esMsg.event_type = ES_EVENT_TYPE_NOTIFY_EXIT;
+  XCTAssertEqual(GetTargetFileForPrefixTree(&esMsg), nullptr);
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityTamperResistance.h

@@ -0,0 +1,33 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+#include <memory>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityClient.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityEventHandler.h"
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
+
+/// ES Client focused on mitigating accidental or malicious tampering of Santa and its components.
+@interface SNTEndpointSecurityTamperResistance
+    : SNTEndpointSecurityClient <SNTEndpointSecurityEventHandler>
+
+- (instancetype)
+  initWithESAPI:
+    (std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI>)esApi
+         logger:(std::shared_ptr<santa::santad::logs::endpoint_security::Logger>)logger;
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityTamperResistance.mm

@@ -0,0 +1,113 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/santad/EventProviders/SNTEndpointSecurityTamperResistance.h"
+
+#include <EndpointSecurity/ESTypes.h>
+#include <string.h>
+
+#import "Source/common/SNTLogging.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::Logger;
+
+static constexpr std::string_view kSantaKextIdentifier = "com.google.santa-driver";
+
+@implementation SNTEndpointSecurityTamperResistance {
+  std::shared_ptr<Logger> _logger;
+}
+
+- (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi
+                       logger:(std::shared_ptr<Logger>)logger {
+  self = [super initWithESAPI:std::move(esApi)];
+  if (self) {
+    _logger = logger;
+
+    [self establishClientOrDie];
+  }
+  return self;
+}
+
+- (void)handleMessage:(Message &&)esMsg {
+  switch (esMsg->event_type) {
+    case ES_EVENT_TYPE_AUTH_UNLINK: {
+      if ([SNTEndpointSecurityTamperResistance
+            isDatabasePath:esMsg->event.unlink.target->path.data]) {
+        // Do not cache so that each attempt to remove santa is logged
+        [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_DENY cacheable:false];
+        LOGW(@"Preventing attempt to delete Santa databases!");
+      } else {
+        [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_ALLOW cacheable:true];
+      }
+
+      return;
+    }
+
+    case ES_EVENT_TYPE_AUTH_RENAME: {
+      if ([SNTEndpointSecurityTamperResistance
+            isDatabasePath:esMsg->event.rename.source->path.data]) {
+        // Do not cache so that each attempt to remove santa is logged
+        [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_DENY cacheable:false];
+        LOGW(@"Preventing attempt to rename Santa databases!");
+        return;
+      }
+
+      if (esMsg->event.rename.destination_type == ES_DESTINATION_TYPE_EXISTING_FILE) {
+        if ([SNTEndpointSecurityTamperResistance
+              isDatabasePath:esMsg->event.rename.destination.existing_file->path.data]) {
+          [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_DENY cacheable:false];
+          LOGW(@"Preventing attempt to overwrite Santa databases!");
+          return;
+        }
+      }
+
+      // If we get to here, no more reasons to deny the event, so allow it
+      [self respondToMessage:esMsg withAuthResult:ES_AUTH_RESULT_ALLOW cacheable:true];
+      return;
+    }
+
+    case ES_EVENT_TYPE_AUTH_KEXTLOAD: {
+      // TODO(mlw): Since we don't package the kext anymore, we should consider removing this.
+      // TODO(mlw): Consider logging when kext loads are attempted.
+      es_auth_result_t res = ES_AUTH_RESULT_ALLOW;
+      if (strcmp(esMsg->event.kextload.identifier.data, kSantaKextIdentifier.data()) == 0) {
+        LOGW(@"Preventing attempt to load Santa kext!");
+        res = ES_AUTH_RESULT_DENY;
+      }
+      [self respondToMessage:esMsg withAuthResult:res cacheable:true];
+      return;
+    }
+
+    default:
+      // Unexpected event type, this is a programming error
+      [NSException raise:@"Invalid event type"
+                  format:@"Invalid tamper resistance event type: %d", esMsg->event_type];
+  }
+}
+
+- (void)enable {
+  // TODO(mlw): For macOS 13, use new mute and invert APIs to limit the
+  // messages sent for these events to the Santa-specific directories
+  // checked in the `handleMessage:` method.
+
+  [super subscribeAndClearCache:{
+                                  ES_EVENT_TYPE_AUTH_KEXTLOAD,
+                                  ES_EVENT_TYPE_AUTH_UNLINK,
+                                  ES_EVENT_TYPE_AUTH_RENAME,
+                                }];
+}
+
+@end

Source/santad/EventProviders/SNTEndpointSecurityTamperResistanceTest.mm

@@ -0,0 +1,190 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/ESTypes.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <map>
+#include <memory>
+#include <set>
+
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Client.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#import "Source/santad/EventProviders/SNTEndpointSecurityTamperResistance.h"
+
+using santa::santad::event_providers::endpoint_security::Client;
+using santa::santad::event_providers::endpoint_security::Message;
+
+static constexpr std::string_view kEventsDBPath = "/private/var/db/santa/events.db";
+static constexpr std::string_view kRulesDBPath = "/private/var/db/santa/rules.db";
+static constexpr std::string_view kBenignPath = "/some/other/path";
+static constexpr std::string_view kSantaKextIdentifier = "com.google.santa-driver";
+
+@interface SNTEndpointSecurityTamperResistanceTest : XCTestCase
+@end
+
+@implementation SNTEndpointSecurityTamperResistanceTest
+
+- (void)testEnable {
+  // Ensure the client subscribes to expected event types
+  std::set<es_event_type_t> expectedEventSubs{
+    ES_EVENT_TYPE_AUTH_KEXTLOAD,
+    ES_EVENT_TYPE_AUTH_UNLINK,
+    ES_EVENT_TYPE_AUTH_RENAME,
+  };
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  EXPECT_CALL(*mockESApi, NewClient(testing::_))
+    .WillOnce(testing::Return(Client(nullptr, ES_NEW_CLIENT_RESULT_SUCCESS)));
+  EXPECT_CALL(*mockESApi, MuteProcess(testing::_, testing::_)).WillOnce(testing::Return(true));
+  EXPECT_CALL(*mockESApi, ClearCache(testing::_))
+    .After(EXPECT_CALL(*mockESApi, Subscribe(testing::_, expectedEventSubs))
+             .WillOnce(testing::Return(true)))
+    .WillOnce(testing::Return(true));
+
+  SNTEndpointSecurityTamperResistance *tamperClient =
+    [[SNTEndpointSecurityTamperResistance alloc] initWithESAPI:mockESApi logger:nullptr];
+  id mockTamperClient = OCMPartialMock(tamperClient);
+
+  [mockTamperClient enable];
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  [mockTamperClient stopMocking];
+}
+
+- (void)testHandleMessage {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_AUTH_EXEC, &proc, ActionType::Auth);
+
+  es_file_t fileEventsDB = MakeESFile(kEventsDBPath.data());
+  es_file_t fileRulesDB = MakeESFile(kRulesDBPath.data());
+  es_file_t fileBenign = MakeESFile(kBenignPath.data());
+
+  es_string_token_t santaTok = MakeESStringToken(kSantaKextIdentifier.data());
+  es_string_token_t benignTok = MakeESStringToken(kBenignPath.data());
+
+  std::map<es_file_t *, es_auth_result_t> pathToResult{
+    {&fileEventsDB, ES_AUTH_RESULT_DENY},
+    {&fileRulesDB, ES_AUTH_RESULT_DENY},
+    {&fileBenign, ES_AUTH_RESULT_ALLOW},
+  };
+
+  std::map<es_string_token_t *, es_auth_result_t> kextIdToResult{
+    {&santaTok, ES_AUTH_RESULT_DENY},
+    {&benignTok, ES_AUTH_RESULT_ALLOW},
+  };
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsESNewClient();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  SNTEndpointSecurityTamperResistance *tamperClient =
+    [[SNTEndpointSecurityTamperResistance alloc] initWithESAPI:mockESApi logger:nullptr];
+
+  id mockTamperClient = OCMPartialMock(tamperClient);
+
+  // Unable to use `OCMExpect` here because we cannot match on the `Message`
+  // parameter. In order to verify the `AuthResult` and `Cacheable` parameters,
+  // instead use `OCMStub` and extract the arguments in order to assert their
+  // expected values.
+  __block es_auth_result_t gotAuthResult;
+  __block bool gotCachable;
+  OCMStub([mockTamperClient respondToMessage:Message(mockESApi, &esMsg)
+                              withAuthResult:(es_auth_result_t)0
+                                   cacheable:false])
+    .ignoringNonObjectArgs()
+    .andDo(^(NSInvocation *inv) {
+      [inv getArgument:&gotAuthResult atIndex:3];
+      [inv getArgument:&gotCachable atIndex:4];
+    });
+
+  // First check unhandled event types will crash
+  {
+    Message msg(mockESApi, &esMsg);
+    XCTAssertThrows([tamperClient handleMessage:Message(mockESApi, &esMsg)]);
+  }
+
+  // Check UNLINK tamper events
+  {
+    esMsg.event_type = ES_EVENT_TYPE_AUTH_UNLINK;
+    for (const auto &kv : pathToResult) {
+      Message msg(mockESApi, &esMsg);
+      esMsg.event.unlink.target = kv.first;
+
+      [mockTamperClient handleMessage:std::move(msg)];
+
+      XCTAssertEqual(gotAuthResult, kv.second);
+      XCTAssertEqual(gotCachable, kv.second == ES_AUTH_RESULT_ALLOW);
+    }
+  }
+
+  // Check RENAME `source` tamper events
+  {
+    esMsg.event_type = ES_EVENT_TYPE_AUTH_RENAME;
+    for (const auto &kv : pathToResult) {
+      Message msg(mockESApi, &esMsg);
+      esMsg.event.rename.source = kv.first;
+      esMsg.event.rename.destination_type = ES_DESTINATION_TYPE_NEW_PATH;
+
+      [mockTamperClient handleMessage:std::move(msg)];
+
+      XCTAssertEqual(gotAuthResult, kv.second);
+      XCTAssertEqual(gotCachable, kv.second == ES_AUTH_RESULT_ALLOW);
+    }
+  }
+
+  // Check RENAME `dest` tamper events
+  {
+    esMsg.event_type = ES_EVENT_TYPE_AUTH_RENAME;
+    esMsg.event.rename.source = &fileBenign;
+    for (const auto &kv : pathToResult) {
+      Message msg(mockESApi, &esMsg);
+      esMsg.event.rename.destination_type = ES_DESTINATION_TYPE_EXISTING_FILE;
+      esMsg.event.rename.destination.existing_file = kv.first;
+
+      [mockTamperClient handleMessage:std::move(msg)];
+
+      XCTAssertEqual(gotAuthResult, kv.second);
+      XCTAssertEqual(gotCachable, kv.second == ES_AUTH_RESULT_ALLOW);
+    }
+  }
+
+  // Check KEXTLOAD tamper events
+  {
+    esMsg.event_type = ES_EVENT_TYPE_AUTH_KEXTLOAD;
+
+    for (const auto &kv : kextIdToResult) {
+      Message msg(mockESApi, &esMsg);
+      esMsg.event.kextload.identifier = *kv.first;
+
+      [mockTamperClient handleMessage:std::move(msg)];
+
+      XCTAssertEqual(gotAuthResult, kv.second);
+      XCTAssertEqual(gotCachable, true);  // Note: Kext responses always cached
+    }
+  }
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTAssertTrue(OCMVerifyAll(mockTamperClient));
+
+  [mockTamperClient stopMocking];
+}
+
+@end

Source/santad/EventProviders/SNTEventProvider.h

@@ -1,33 +0,0 @@
-/// Copyright 2019 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import <Foundation/Foundation.h>
-
-#include "Source/common/SNTCommon.h"
-
-@protocol SNTEventProvider <NSObject>
-
-- (void)listenForDecisionRequests:(void (^)(santa_message_t message))callback;
-- (void)listenForLogRequests:(void (^)(santa_message_t message))callback;
-- (int)postAction:(santa_action_t)action forMessage:(santa_message_t)sm;
-- (BOOL)flushCacheNonRootOnly:(BOOL)nonRootOnly;
-- (void)fileModificationPrefixFilterAdd:(NSArray *)filters;
-- (void)fileModificationPrefixFilterReset;
-- (NSArray<NSNumber *> *)cacheCounts;
-- (NSArray<NSNumber *> *)cacheBucketCount;
-- (santa_action_t)checkCache:(santa_vnode_id_t)vnodeID;
-- (kern_return_t)removeCacheEntryForVnodeID:(santa_vnode_id_t)vnodeId;
-@property(readonly) BOOL connectionEstablished;
-
-@end

Source/santad/Logs/EndpointSecurity/Logger.h

@@ -0,0 +1,69 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_LOGGER_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_LOGGER_H
+
+#include <memory>
+#include <string_view>
+
+#import <Foundation/Foundation.h>
+
+#import "Source/common/SNTCommonEnums.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Writer.h"
+
+// Forward declarations
+@class SNTStoredEvent;
+namespace santa::santad::logs::endpoint_security {
+class LoggerPeer;
+}
+
+namespace santa::santad::logs::endpoint_security {
+
+class Logger {
+ public:
+  static std::unique_ptr<Logger> Create(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi,
+    SNTEventLogType log_type, NSString *event_log_path);
+
+  Logger(std::shared_ptr<serializers::Serializer> serializer,
+         std::shared_ptr<writers::Writer> writer);
+
+  virtual ~Logger() = default;
+
+  virtual void Log(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EnrichedMessage> msg);
+
+  void LogAllowlist(const santa::santad::event_providers::endpoint_security::Message &msg,
+                    const std::string_view hash);
+
+  void LogBundleHashingEvents(NSArray<SNTStoredEvent *> *events);
+
+  void LogDiskAppeared(NSDictionary *props);
+  void LogDiskDisappeared(NSDictionary *props);
+
+  friend class santa::santad::logs::endpoint_security::LoggerPeer;
+
+ private:
+  std::shared_ptr<serializers::Serializer> serializer_;
+  std::shared_ptr<writers::Writer> writer_;
+};
+
+}  // namespace santa::santad::logs::endpoint_security
+
+#endif

Source/santad/Logs/EndpointSecurity/Logger.mm

@@ -0,0 +1,89 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
+
+#include "Source/common/SNTCommonEnums.h"
+#include "Source/common/SNTLogging.h"
+#include "Source/common/SNTStoredEvent.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/BasicString.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Empty.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/File.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Null.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Syslog.h"
+
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::serializers::BasicString;
+using santa::santad::logs::endpoint_security::serializers::Empty;
+using santa::santad::logs::endpoint_security::writers::File;
+using santa::santad::logs::endpoint_security::writers::Null;
+using santa::santad::logs::endpoint_security::writers::Syslog;
+
+namespace santa::santad::logs::endpoint_security {
+
+// Flush the write buffer every 5 seconds
+static const uint64_t kFlushBufferTimeoutMS = 10000;
+// Batch writes up to 128kb
+static const size_t kBufferBatchSizeBytes = (1024 * 128);
+// Reserve an extra 4kb of buffer space to account for event overflow
+static const size_t kMaxExpectedWriteSizeBytes = 4096;
+
+// Translate configured log type to appropriate Serializer/Writer pairs
+std::unique_ptr<Logger> Logger::Create(std::shared_ptr<EndpointSecurityAPI> esapi,
+                                       SNTEventLogType log_type, NSString *event_log_path) {
+  switch (log_type) {
+    case SNTEventLogTypeFilelog:
+      return std::make_unique<Logger>(
+        BasicString::Create(esapi),
+        File::Create(event_log_path, kFlushBufferTimeoutMS, kBufferBatchSizeBytes,
+                     kMaxExpectedWriteSizeBytes));
+    case SNTEventLogTypeSyslog:
+      return std::make_unique<Logger>(BasicString::Create(esapi, false), Syslog::Create());
+    case SNTEventLogTypeNull: return std::make_unique<Logger>(Empty::Create(), Null::Create());
+    case SNTEventLogTypeProtobuf:
+      LOGE(@"The EventLogType value protobuf is not supported in this release");
+      return nullptr;
+    default: LOGE(@"Invalid log type: %ld", log_type); return nullptr;
+  }
+}
+
+Logger::Logger(std::shared_ptr<serializers::Serializer> serializer,
+               std::shared_ptr<writers::Writer> writer)
+    : serializer_(std::move(serializer)), writer_(std::move(writer)) {}
+
+void Logger::Log(std::shared_ptr<EnrichedMessage> msg) {
+  writer_->Write(serializer_->SerializeMessage(std::move(msg)));
+}
+
+void Logger::LogAllowlist(const Message &msg, const std::string_view hash) {
+  writer_->Write(serializer_->SerializeAllowlist(msg, hash));
+}
+
+void Logger::LogBundleHashingEvents(NSArray<SNTStoredEvent *> *events) {
+  for (SNTStoredEvent *se in events) {
+    writer_->Write(serializer_->SerializeBundleHashingEvent(se));
+  }
+}
+
+void Logger::LogDiskAppeared(NSDictionary *props) {
+  writer_->Write(serializer_->SerializeDiskAppeared(props));
+}
+
+void Logger::LogDiskDisappeared(NSDictionary *props) {
+  writer_->Write(serializer_->SerializeDiskDisappeared(props));
+}
+
+}  // namespace santa::santad::logs::endpoint_security

Source/santad/Logs/EndpointSecurity/LoggerTest.mm

@@ -0,0 +1,198 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <Foundation/Foundation.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <memory>
+#include <optional>
+#include <string_view>
+#include <vector>
+
+#include "Source/common/SNTCommonEnums.h"
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#include "Source/santad/Logs/EndpointSecurity/Logger.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/BasicString.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Empty.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/File.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Null.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Syslog.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Writer.h"
+
+using santa::santad::event_providers::endpoint_security::EnrichedClose;
+using santa::santad::event_providers::endpoint_security::EnrichedFile;
+using santa::santad::event_providers::endpoint_security::EnrichedMessage;
+using santa::santad::event_providers::endpoint_security::EnrichedProcess;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::Logger;
+using santa::santad::logs::endpoint_security::serializers::BasicString;
+using santa::santad::logs::endpoint_security::serializers::Empty;
+using santa::santad::logs::endpoint_security::writers::File;
+using santa::santad::logs::endpoint_security::writers::Null;
+using santa::santad::logs::endpoint_security::writers::Syslog;
+
+namespace santa::santad::logs::endpoint_security {
+
+class LoggerPeer : public Logger {
+ public:
+  // Make base class constructors visible
+  using Logger::Logger;
+
+  LoggerPeer(std::unique_ptr<Logger> l) : Logger(l->serializer_, l->writer_) {}
+
+  std::shared_ptr<serializers::Serializer> Serializer() { return serializer_; }
+
+  std::shared_ptr<writers::Writer> Writer() { return writer_; }
+};
+
+}  // namespace santa::santad::logs::endpoint_security
+
+using santa::santad::logs::endpoint_security::LoggerPeer;
+
+class MockSerializer : public Empty {
+ public:
+  MOCK_METHOD(std::vector<uint8_t>, SerializeMessage, (const EnrichedClose &msg));
+
+  MOCK_METHOD(std::vector<uint8_t>, SerializeAllowlist, (const Message &, const std::string_view));
+
+  MOCK_METHOD(std::vector<uint8_t>, SerializeBundleHashingEvent, (SNTStoredEvent *));
+  MOCK_METHOD(std::vector<uint8_t>, SerializeDiskAppeared, (NSDictionary *));
+  MOCK_METHOD(std::vector<uint8_t>, SerializeDiskDisappeared, (NSDictionary *));
+};
+
+class MockWriter : public Null {
+ public:
+  MOCK_METHOD(void, Write, (std::vector<uint8_t> && bytes));
+};
+
+@interface LoggerTest : XCTestCase
+@end
+
+@implementation LoggerTest
+
+- (void)testCreate {
+  // Ensure that the factory method creates expected serializers/writers pairs
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+
+  XCTAssertEqual(nullptr, Logger::Create(mockESApi, (SNTEventLogType)123, @"/tmp"));
+  XCTAssertEqual(nullptr, Logger::Create(mockESApi, SNTEventLogTypeProtobuf, @"/tmp"));
+
+  LoggerPeer logger(Logger::Create(mockESApi, SNTEventLogTypeFilelog, @"/tmp/temppy"));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<BasicString>(logger.Serializer()));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<File>(logger.Writer()));
+
+  logger = LoggerPeer(Logger::Create(mockESApi, SNTEventLogTypeSyslog, @"/tmp/temppy"));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<BasicString>(logger.Serializer()));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<Syslog>(logger.Writer()));
+
+  logger = LoggerPeer(Logger::Create(mockESApi, SNTEventLogTypeNull, @"/tmp/temppy"));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<Empty>(logger.Serializer()));
+  XCTAssertNotEqual(nullptr, std::dynamic_pointer_cast<Null>(logger.Writer()));
+}
+
+- (void)testLog {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  auto mockSerializer = std::make_shared<MockSerializer>();
+  auto mockWriter = std::make_shared<MockWriter>();
+
+  // Ensure all Logger::Log* methods call the serializer followed by the writer
+  es_message_t msg;
+
+  // Note: In this test, `RetainMessage` isn't setup to return anything. This
+  // means that the underlying `es_msg_` in the `Message` object is NULL, and
+  // therefore no call to `ReleaseMessage` is ever made (hence no expectations).
+  // Because we don't need to operate on the es_msg_, this simplifies the test.
+  EXPECT_CALL(*mockESApi, RetainMessage);
+  auto enrichedMsg = std::make_shared<EnrichedMessage>(
+    EnrichedClose(Message(mockESApi, &msg),
+                  EnrichedProcess(std::nullopt, std::nullopt, std::nullopt, std::nullopt,
+                                  EnrichedFile(std::nullopt, std::nullopt, std::nullopt)),
+                  EnrichedFile(std::nullopt, std::nullopt, std::nullopt)));
+
+  EXPECT_CALL(*mockSerializer, SerializeMessage(testing::A<const EnrichedClose &>())).Times(1);
+  EXPECT_CALL(*mockWriter, Write).Times(1);
+
+  Logger(mockSerializer, mockWriter).Log(enrichedMsg);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockSerializer.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockWriter.get());
+}
+
+- (void)testLogAllowList {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  auto mockSerializer = std::make_shared<MockSerializer>();
+  auto mockWriter = std::make_shared<MockWriter>();
+  es_message_t msg;
+  std::string_view hash = "this_is_my_test_hash";
+
+  EXPECT_CALL(*mockESApi, RetainMessage);
+  EXPECT_CALL(*mockSerializer, SerializeAllowlist(testing::_, hash));
+  EXPECT_CALL(*mockWriter, Write);
+
+  Logger(mockSerializer, mockWriter).LogAllowlist(Message(mockESApi, &msg), hash);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockSerializer.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockWriter.get());
+}
+
+- (void)testLogBundleHashingEvents {
+  auto mockSerializer = std::make_shared<MockSerializer>();
+  auto mockWriter = std::make_shared<MockWriter>();
+  NSArray<id> *events = @[ @"event1", @"event2", @"event3" ];
+
+  EXPECT_CALL(*mockSerializer, SerializeBundleHashingEvent).Times((int)[events count]);
+  EXPECT_CALL(*mockWriter, Write).Times((int)[events count]);
+
+  Logger(mockSerializer, mockWriter).LogBundleHashingEvents(events);
+
+  XCTBubbleMockVerifyAndClearExpectations(mockSerializer.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockWriter.get());
+}
+
+- (void)testLogDiskAppeared {
+  auto mockSerializer = std::make_shared<MockSerializer>();
+  auto mockWriter = std::make_shared<MockWriter>();
+
+  EXPECT_CALL(*mockSerializer, SerializeDiskAppeared);
+  EXPECT_CALL(*mockWriter, Write);
+
+  Logger(mockSerializer, mockWriter).LogDiskAppeared(@{@"key" : @"value"});
+
+  XCTBubbleMockVerifyAndClearExpectations(mockSerializer.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockWriter.get());
+}
+
+- (void)testLogDiskDisappeared {
+  auto mockSerializer = std::make_shared<MockSerializer>();
+  auto mockWriter = std::make_shared<MockWriter>();
+
+  EXPECT_CALL(*mockSerializer, SerializeDiskDisappeared);
+  EXPECT_CALL(*mockWriter, Write);
+
+  Logger(mockSerializer, mockWriter).LogDiskDisappeared(@{@"key" : @"value"});
+
+  XCTBubbleMockVerifyAndClearExpectations(mockSerializer.get());
+  XCTBubbleMockVerifyAndClearExpectations(mockWriter.get());
+}
+
+@end

Source/santad/Logs/EndpointSecurity/Serializers/BasicString.h

@@ -0,0 +1,74 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_BASICSTRING_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_BASICSTRING_H
+
+#import <Foundation/Foundation.h>
+
+#include <memory>
+#include <sstream>
+#include <vector>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+class BasicString : public Serializer {
+ public:
+  static std::shared_ptr<BasicString> Create(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi,
+    bool prefix_time_name = true);
+
+  BasicString(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi,
+    bool prefix_time_name);
+
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedClose &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExchange &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExec &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExit &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedFork &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedLink &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedRename &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedUnlink &) override;
+
+  std::vector<uint8_t> SerializeAllowlist(
+    const santa::santad::event_providers::endpoint_security::Message &,
+    const std::string_view) override;
+
+  std::vector<uint8_t> SerializeBundleHashingEvent(SNTStoredEvent *) override;
+
+  std::vector<uint8_t> SerializeDiskAppeared(NSDictionary *) override;
+  std::vector<uint8_t> SerializeDiskDisappeared(NSDictionary *) override;
+
+ private:
+  std::string CreateDefaultString(size_t reserved_size = 512);
+
+  std::shared_ptr<santa::santad::event_providers::endpoint_security::EndpointSecurityAPI> esapi_;
+  bool prefix_time_name_;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::serializers
+
+#endif

Source/santad/Logs/EndpointSecurity/Serializers/BasicString.mm

@@ -0,0 +1,608 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/BasicString.h"
+
+#import <Security/Security.h>
+#include <bsm/libbsm.h>
+#include <libgen.h>
+#include <mach/message.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/kauth.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <string>
+
+#import "Source/common/SNTCachedDecision.h"
+#import "Source/common/SNTConfigurator.h"
+#import "Source/common/SNTLogging.h"
+#import "Source/common/SNTStoredEvent.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/SanitizableString.h"
+#import "Source/santad/SNTDecisionCache.h"
+
+using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
+using santa::santad::event_providers::endpoint_security::EnrichedClose;
+using santa::santad::event_providers::endpoint_security::EnrichedExchange;
+using santa::santad::event_providers::endpoint_security::EnrichedExec;
+using santa::santad::event_providers::endpoint_security::EnrichedExit;
+using santa::santad::event_providers::endpoint_security::EnrichedFork;
+using santa::santad::event_providers::endpoint_security::EnrichedLink;
+using santa::santad::event_providers::endpoint_security::EnrichedRename;
+using santa::santad::event_providers::endpoint_security::EnrichedUnlink;
+using santa::santad::event_providers::endpoint_security::Message;
+
+// These functions are exported by the Security framework, but are not included in headers
+extern "C" Boolean SecTranslocateIsTranslocatedURL(CFURLRef path, bool *isTranslocated,
+                                                   CFErrorRef *__nullable error);
+extern "C" CFURLRef __nullable SecTranslocateCreateOriginalPathForURL(CFURLRef translocatedPath,
+                                                                      CFErrorRef *__nullable error);
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+static inline SanitizableString FilePath(const es_file_t *file) {
+  return SanitizableString(file);
+}
+
+static inline pid_t Pid(const audit_token_t &tok) {
+  return audit_token_to_pid(tok);
+}
+
+static inline pid_t Pidversion(const audit_token_t &tok) {
+  return audit_token_to_pidversion(tok);
+}
+
+static inline pid_t RealUser(const audit_token_t &tok) {
+  return audit_token_to_ruid(tok);
+}
+
+static inline pid_t RealGroup(const audit_token_t &tok) {
+  return audit_token_to_rgid(tok);
+}
+
+static inline void SetThreadIDs(uid_t uid, gid_t gid) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated"
+  pthread_setugid_np(uid, gid);
+#pragma clang diagnostic pop
+}
+
+static inline const mach_port_t GetDefaultIOKitCommsPort() {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return kIOMasterPortDefault;
+#pragma clang diagnostic pop
+}
+
+static NSString *SerialForDevice(NSString *devPath) {
+  if (!devPath.length) {
+    return nil;
+  }
+  NSString *serial;
+  io_registry_entry_t device =
+    IORegistryEntryFromPath(GetDefaultIOKitCommsPort(), devPath.UTF8String);
+  while (!serial && device) {
+    CFMutableDictionaryRef device_properties = NULL;
+    IORegistryEntryCreateCFProperties(device, &device_properties, kCFAllocatorDefault, kNilOptions);
+    NSDictionary *properties = CFBridgingRelease(device_properties);
+    if (properties[@"Serial Number"]) {
+      serial = properties[@"Serial Number"];
+    } else if (properties[@"kUSBSerialNumberString"]) {
+      serial = properties[@"kUSBSerialNumberString"];
+    }
+
+    if (serial) {
+      IOObjectRelease(device);
+      break;
+    }
+
+    io_registry_entry_t parent;
+    IORegistryEntryGetParentEntry(device, kIOServicePlane, &parent);
+    IOObjectRelease(device);
+    device = parent;
+  }
+
+  return [serial stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+}
+
+static NSString *DiskImageForDevice(NSString *devPath) {
+  devPath = [devPath stringByDeletingLastPathComponent];
+  if (!devPath.length) {
+    return nil;
+  }
+
+  io_registry_entry_t device =
+    IORegistryEntryFromPath(GetDefaultIOKitCommsPort(), devPath.UTF8String);
+  CFMutableDictionaryRef device_properties = NULL;
+  IORegistryEntryCreateCFProperties(device, &device_properties, kCFAllocatorDefault, kNilOptions);
+  NSDictionary *properties = CFBridgingRelease(device_properties);
+  IOObjectRelease(device);
+
+  if (properties[@"image-path"]) {
+    NSString *result = [[NSString alloc] initWithData:properties[@"image-path"]
+                                             encoding:NSUTF8StringEncoding];
+    return [result stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+  } else {
+    return nil;
+  }
+}
+
+static NSString *OriginalPathForTranslocation(const es_process_t *esProc) {
+  if (!esProc) {
+    return nil;
+  }
+
+  // Note: Benchmarks showed better performance using `URLWithString` with a `file://` prefix
+  // compared to using `fileURLWithPath`.
+  CFURLRef cfExecURL = (__bridge CFURLRef)
+    [NSURL URLWithString:[NSString stringWithFormat:@"file://%s", esProc->executable->path.data]];
+  NSURL *origURL = nil;
+  bool isTranslocated = false;
+
+  if (SecTranslocateIsTranslocatedURL(cfExecURL, &isTranslocated, NULL) && isTranslocated) {
+    bool dropPrivs = true;
+    if (@available(macOS 12.0, *)) {
+      dropPrivs = false;
+    }
+
+    if (dropPrivs) {
+      SetThreadIDs(RealUser(esProc->audit_token), RealGroup(esProc->audit_token));
+    }
+
+    origURL = CFBridgingRelease(SecTranslocateCreateOriginalPathForURL(cfExecURL, NULL));
+
+    if (dropPrivs) {
+      SetThreadIDs(KAUTH_UID_NONE, KAUTH_GID_NONE);
+    }
+  }
+
+  return [origURL path];
+}
+
+es_file_t *GetAllowListTargetFile(const Message &msg) {
+  switch (msg->event_type) {
+    case ES_EVENT_TYPE_NOTIFY_CLOSE: return msg->event.close.target;
+    case ES_EVENT_TYPE_NOTIFY_RENAME: return msg->event.rename.source;
+    default:
+      // This is a programming error
+      LOGE(@"Unexpected event type for AllowList");
+      [NSException raise:@"Unexpected type"
+                  format:@"Unexpected event type for AllowList: %d", msg->event_type];
+      return nil;
+  }
+}
+
+static NSDateFormatter *GetDateFormatter() {
+  static dispatch_once_t onceToken;
+  static NSDateFormatter *dateFormatter;
+
+  dispatch_once(&onceToken, ^{
+    dateFormatter = [[NSDateFormatter alloc] init];
+    dateFormatter.dateFormat = @"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
+    dateFormatter.calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierISO8601];
+    dateFormatter.timeZone = [NSTimeZone timeZoneWithName:@"UTC"];
+  });
+
+  return dateFormatter;
+}
+
+std::string GetDecisionString(SNTEventState event_state) {
+  if (event_state & SNTEventStateAllow) {
+    return "ALLOW";
+  } else if (event_state & SNTEventStateBlock) {
+    return "DENY";
+  } else {
+    return "UNKNOWN";
+  }
+}
+
+std::string GetReasonString(SNTEventState event_state) {
+  switch (event_state) {
+    case SNTEventStateAllowBinary: return "BINARY";
+    case SNTEventStateAllowCompiler: return "COMPILER";
+    case SNTEventStateAllowTransitive: return "TRANSITIVE";
+    case SNTEventStateAllowPendingTransitive: return "PENDING_TRANSITIVE";
+    case SNTEventStateAllowCertificate: return "CERT";
+    case SNTEventStateAllowScope: return "SCOPE";
+    case SNTEventStateAllowTeamID: return "TEAMID";
+    case SNTEventStateAllowUnknown: return "UNKNOWN";
+    case SNTEventStateBlockBinary: return "BINARY";
+    case SNTEventStateBlockCertificate: return "CERT";
+    case SNTEventStateBlockScope: return "SCOPE";
+    case SNTEventStateBlockTeamID: return "TEAMID";
+    case SNTEventStateBlockLongPath: return "LONG_PATH";
+    case SNTEventStateBlockUnknown: return "UNKNOWN";
+    default: return "NOTRUNNING";
+  }
+}
+
+std::string GetModeString(SNTClientMode mode) {
+  switch (mode) {
+    case SNTClientModeMonitor: return "M";
+    case SNTClientModeLockdown: return "L";
+    default: return "U";
+  }
+}
+
+static inline void AppendProcess(std::string &str, const es_process_t *es_proc) {
+  char bname[MAXPATHLEN];
+  str.append("|pid=");
+  str.append(std::to_string(Pid(es_proc->audit_token)));
+  str.append("|ppid=");
+  str.append(std::to_string(es_proc->original_ppid));
+  str.append("|process=");
+  str.append(basename_r(FilePath(es_proc->executable).Sanitized().data(), bname) ?: "");
+  str.append("|processpath=");
+  str.append(FilePath(es_proc->executable).Sanitized());
+}
+
+static inline void AppendUserGroup(std::string &str, const audit_token_t &tok,
+                                   const std::optional<std::shared_ptr<std::string>> &user,
+                                   const std::optional<std::shared_ptr<std::string>> &group) {
+  str.append("|uid=");
+  str.append(std::to_string(RealUser(tok)));
+  str.append("|user=");
+  str.append(user.has_value() ? user->get()->c_str() : "(null)");
+  str.append("|gid=");
+  str.append(std::to_string(RealGroup(tok)));
+  str.append("|group=");
+  str.append(group.has_value() ? group->get()->c_str() : "(null)");
+}
+
+static char *FormattedDateString(char *buf, size_t len) {
+  struct timeval tv;
+  struct tm tm;
+
+  gettimeofday(&tv, NULL);
+  gmtime_r(&tv.tv_sec, &tm);
+
+  strftime(buf, len, "%Y-%m-%dT%H:%M:%S", &tm);
+  snprintf(buf, len, "%s.%03dZ", buf, tv.tv_usec / 1000);
+
+  return buf;
+}
+
+static inline NSString *NonNull(NSString *str) {
+  return str ?: @"";
+}
+
+std::shared_ptr<BasicString> BasicString::Create(std::shared_ptr<EndpointSecurityAPI> esapi,
+                                                 bool prefix_time_name) {
+  return std::make_shared<BasicString>(esapi, prefix_time_name);
+}
+
+BasicString::BasicString(std::shared_ptr<EndpointSecurityAPI> esapi, bool prefix_time_name)
+    : esapi_(esapi), prefix_time_name_(prefix_time_name) {}
+
+std::string BasicString::CreateDefaultString(size_t reserved_size) {
+  std::string str;
+  str.reserve(1024);
+
+  if (prefix_time_name_) {
+    char buf[32];
+
+    str.append("[");
+    str.append(FormattedDateString(buf, sizeof(buf)));
+    str.append("] I santad: ");
+  }
+
+  return str;
+}
+
+inline std::vector<uint8_t> FinalizeString(std::string &str) {
+  str.append("\n");
+  std::vector<uint8_t> vec(str.length());
+  std::copy(str.begin(), str.end(), vec.begin());
+  return vec;
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedClose &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=WRITE|path=");
+  str.append(FilePath(esm.event.close.target).Sanitized());
+
+  AppendProcess(str, esm.process);
+  AppendUserGroup(str, esm.process->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedExchange &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=EXCHANGE|path=");
+  str.append(FilePath(esm.event.exchangedata.file1).Sanitized());
+  str.append("|newpath=");
+  str.append(FilePath(esm.event.exchangedata.file2).Sanitized());
+
+  AppendProcess(str, esm.process);
+  AppendUserGroup(str, esm.process->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedExec &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString(1024);  // EXECs tend to be bigger, reserve more space.
+
+  SNTCachedDecision *cd =
+    [[SNTDecisionCache sharedCache] cachedDecisionForFile:esm.event.exec.target->executable->stat];
+
+  str.append("action=EXEC|decision=");
+  str.append(GetDecisionString(cd.decision));
+  str.append("|reason=");
+  str.append(GetReasonString(cd.decision));
+
+  if (cd.decisionExtra) {
+    str.append("|explain=");
+    str.append([cd.decisionExtra UTF8String]);
+  }
+
+  if (cd.sha256) {
+    str.append("|sha256=");
+    str.append([cd.sha256 UTF8String]);
+  }
+
+  if (cd.certSHA256) {
+    str.append("|cert_sha256=");
+    str.append([cd.certSHA256 UTF8String]);
+    str.append("|cert_cn=");
+    str.append(SanitizableString(cd.certCommonName).Sanitized());
+  }
+
+  if (cd.teamID.length) {
+    str.append("|teamid=");
+    str.append([NonNull(cd.teamID) UTF8String]);
+  }
+
+  if (cd.quarantineURL) {
+    str.append("|quarantine_url=");
+    str.append(SanitizableString(cd.quarantineURL).Sanitized());
+  }
+
+  str.append("|pid=");
+  str.append(std::to_string(Pid(esm.event.exec.target->audit_token)));
+  str.append("|pidversion=");
+  str.append(std::to_string(Pidversion(esm.event.exec.target->audit_token)));
+  str.append("|ppid=");
+  str.append(std::to_string(esm.event.exec.target->original_ppid));
+
+  AppendUserGroup(str, esm.event.exec.target->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  str.append("|mode=");
+  str.append(GetModeString([[SNTConfigurator configurator] clientMode]));
+  str.append("|path=");
+  str.append(FilePath(esm.event.exec.target->executable).Sanitized());
+
+  NSString *origPath = OriginalPathForTranslocation(esm.event.exec.target);
+  if (origPath) {
+    str.append("|origpath=");
+    str.append(SanitizableString(origPath).Sanitized());
+  }
+
+  uint32_t argCount = esapi_->ExecArgCount(&esm.event.exec);
+  if (argCount > 0) {
+    str.append("|args=");
+    for (uint32_t i = 0; i < argCount; i++) {
+      if (i != 0) {
+        str.append(" ");
+      }
+
+      str.append(SanitizableString(esapi_->ExecArg(&esm.event.exec, i)).Sanitized());
+    }
+  }
+
+  if ([[SNTConfigurator configurator] enableMachineIDDecoration]) {
+    str.append("|machineid=");
+    str.append([NonNull([[SNTConfigurator configurator] machineID]) UTF8String]);
+  }
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedExit &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=EXIT|pid=");
+  str.append(std::to_string(Pid(esm.process->audit_token)));
+  str.append("|pidversion=");
+  str.append(std::to_string(Pidversion(esm.process->audit_token)));
+  str.append("|ppid=");
+  str.append(std::to_string(esm.process->original_ppid));
+  str.append("|uid=");
+  str.append(std::to_string(RealUser(esm.process->audit_token)));
+  str.append("|gid=");
+  str.append(std::to_string(RealGroup(esm.process->audit_token)));
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedFork &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=FORK|pid=");
+  str.append(std::to_string(Pid(esm.event.fork.child->audit_token)));
+  str.append("|pidversion=");
+  str.append(std::to_string(Pidversion(esm.event.fork.child->audit_token)));
+  str.append("|ppid=");
+  str.append(std::to_string(esm.event.fork.child->original_ppid));
+  str.append("|uid=");
+  str.append(std::to_string(RealUser(esm.event.fork.child->audit_token)));
+  str.append("|gid=");
+  str.append(std::to_string(RealGroup(esm.event.fork.child->audit_token)));
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedLink &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=LINK|path=");
+  str.append(FilePath(esm.event.link.source).Sanitized());
+  str.append("|newpath=");
+  str.append(FilePath(esm.event.link.target_dir).Sanitized());
+  str.append("/");
+  str.append(SanitizableString(esm.event.link.target_filename).Sanitized());
+
+  AppendProcess(str, esm.process);
+  AppendUserGroup(str, esm.process->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedRename &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=RENAME|path=");
+  str.append(FilePath(esm.event.rename.source).Sanitized());
+  str.append("|newpath=");
+
+  switch (esm.event.rename.destination_type) {
+    case ES_DESTINATION_TYPE_EXISTING_FILE:
+      str.append(FilePath(esm.event.rename.destination.existing_file).Sanitized());
+      break;
+    case ES_DESTINATION_TYPE_NEW_PATH:
+      str.append(FilePath(esm.event.rename.destination.new_path.dir).Sanitized());
+      str.append("/");
+      str.append(SanitizableString(esm.event.rename.destination.new_path.filename).Sanitized());
+      break;
+    default: str.append("(null)"); break;
+  }
+
+  AppendProcess(str, esm.process);
+  AppendUserGroup(str, esm.process->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeMessage(const EnrichedUnlink &msg) {
+  const es_message_t &esm = msg.es_msg();
+  std::string str = CreateDefaultString();
+
+  str.append("action=DELETE|path=");
+  str.append(FilePath(esm.event.unlink.target).Sanitized());
+
+  AppendProcess(str, esm.process);
+  AppendUserGroup(str, esm.process->audit_token, msg.instigator().real_user(),
+                  msg.instigator().real_group());
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeAllowlist(const Message &msg,
+                                                     const std::string_view hash) {
+  std::string str = CreateDefaultString();
+
+  str.append("action=ALLOWLIST|pid=");
+  str.append(std::to_string(Pid(msg->process->audit_token)));
+  str.append("|pidversion=");
+  str.append(std::to_string(Pidversion(msg->process->audit_token)));
+  str.append("|path=");
+  str.append(FilePath(GetAllowListTargetFile(msg)).Sanitized());
+  str.append("|sha256=");
+  str.append(hash);
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeBundleHashingEvent(SNTStoredEvent *event) {
+  std::string str = CreateDefaultString();
+
+  str.append("action=BUNDLE|sha256=");
+  str.append([NonNull(event.fileSHA256) UTF8String]);
+  str.append("|bundlehash=");
+  str.append([NonNull(event.fileBundleHash) UTF8String]);
+  str.append("|bundlename=");
+  str.append([NonNull(event.fileBundleName) UTF8String]);
+  str.append("|bundleid=");
+  str.append([NonNull(event.fileBundleID) UTF8String]);
+  str.append("|bundlepath=");
+  str.append([NonNull(event.fileBundlePath) UTF8String]);
+  str.append("|path=");
+  str.append([NonNull(event.filePath) UTF8String]);
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeDiskAppeared(NSDictionary *props) {
+  NSString *dmgPath = nil;
+  NSString *serial = nil;
+  if ([props[@"DADeviceModel"] isEqual:@"Disk Image"]) {
+    dmgPath = DiskImageForDevice(props[@"DADevicePath"]);
+  } else {
+    serial = SerialForDevice(props[@"DADevicePath"]);
+  }
+
+  NSString *model = [NSString
+    stringWithFormat:@"%@ %@", NonNull(props[@"DADeviceVendor"]), NonNull(props[@"DADeviceModel"])];
+  model = [model stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+
+  NSString *appearanceDateString = [GetDateFormatter()
+    stringFromDate:[NSDate dateWithTimeIntervalSinceReferenceDate:[props[@"DAAppearanceTime"]
+                                                                    doubleValue]]];
+
+  std::string str = CreateDefaultString();
+  str.append("action=DISKAPPEAR");
+  str.append("|mount=");
+  str.append([NonNull([props[@"DAVolumePath"] path]) UTF8String]);
+  str.append("|volume=");
+  str.append([NonNull(props[@"DAVolumeName"]) UTF8String]);
+  str.append("|bsdname=");
+  str.append([NonNull(props[@"DAMediaBSDName"]) UTF8String]);
+  str.append("|fs=");
+  str.append([NonNull(props[@"DAVolumeKind"]) UTF8String]);
+  str.append("|model=");
+  str.append([NonNull(model) UTF8String]);
+  str.append("|serial=");
+  str.append([NonNull(serial) UTF8String]);
+  str.append("|bus=");
+  str.append([NonNull(props[@"DADeviceProtocol"]) UTF8String]);
+  str.append("|dmgpath=");
+  str.append([NonNull(dmgPath) UTF8String]);
+  str.append("|appearance=");
+  str.append([NonNull(appearanceDateString) UTF8String]);
+
+  return FinalizeString(str);
+}
+
+std::vector<uint8_t> BasicString::SerializeDiskDisappeared(NSDictionary *props) {
+  std::string str = CreateDefaultString();
+
+  str.append("action=DISKDISAPPEAR");
+  str.append("|mount=");
+  str.append([NonNull([props[@"DAVolumePath"] path]) UTF8String]);
+  str.append("|volume=");
+  str.append([NonNull(props[@"DAVolumeName"]) UTF8String]);
+  str.append("|bsdname=");
+  str.append([NonNull(props[@"DAMediaBSDName"]) UTF8String]);
+
+  return FinalizeString(str);
+}
+
+}  // namespace santa::santad::logs::endpoint_security::serializers

Source/santad/Logs/EndpointSecurity/Serializers/BasicStringTest.mm

@@ -0,0 +1,418 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include <EndpointSecurity/ESTypes.h>
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <Foundation/Foundation.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <bsm/libbsm.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <map>
+#include <string>
+
+#import "Source/common/SNTCachedDecision.h"
+#import "Source/common/SNTCommonEnums.h"
+#import "Source/common/SNTConfigurator.h"
+#import "Source/common/SNTStoredEvent.h"
+#include "Source/common/TestUtils.h"
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
+#include "Source/santad/EventProviders/EndpointSecurity/Message.h"
+#include "Source/santad/EventProviders/EndpointSecurity/MockEndpointSecurityAPI.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/BasicString.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+#import "Source/santad/SNTDecisionCache.h"
+
+using santa::santad::event_providers::endpoint_security::Enricher;
+using santa::santad::event_providers::endpoint_security::Message;
+using santa::santad::logs::endpoint_security::serializers::BasicString;
+using santa::santad::logs::endpoint_security::serializers::Serializer;
+
+namespace santa::santad::logs::endpoint_security::serializers {
+extern es_file_t *GetAllowListTargetFile(const Message &msg);
+extern std::string GetDecisionString(SNTEventState event_state);
+extern std::string GetReasonString(SNTEventState event_state);
+extern std::string GetModeString(SNTClientMode mode);
+}  // namespace santa::santad::logs::endpoint_security::serializers
+
+using santa::santad::logs::endpoint_security::serializers::GetAllowListTargetFile;
+using santa::santad::logs::endpoint_security::serializers::GetDecisionString;
+using santa::santad::logs::endpoint_security::serializers::GetModeString;
+using santa::santad::logs::endpoint_security::serializers::GetReasonString;
+
+std::string BasicStringSerializeMessage(std::shared_ptr<MockEndpointSecurityAPI> mockESApi,
+                                        es_message_t *esMsg) {
+  mockESApi->SetExpectationsRetainReleaseMessage(esMsg);
+
+  std::shared_ptr<Serializer> bs = BasicString::Create(mockESApi, false);
+  std::vector<uint8_t> ret = bs->SerializeMessage(Enricher().Enrich(Message(mockESApi, esMsg)));
+
+  XCTBubbleMockVerifyAndClearExpectations(mockESApi.get());
+
+  return std::string(ret.begin(), ret.end());
+}
+
+std::string BasicStringSerializeMessage(es_message_t *esMsg) {
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  return BasicStringSerializeMessage(mockESApi, esMsg);
+}
+
+@interface BasicStringTest : XCTestCase
+@property id mockConfigurator;
+@property id mockDecisionCache;
+
+@property SNTCachedDecision *testCachedDecision;
+@end
+
+@implementation BasicStringTest
+
+- (void)setUp {
+  self.mockConfigurator = OCMClassMock([SNTConfigurator class]);
+  OCMStub([self.mockConfigurator configurator]).andReturn(self.mockConfigurator);
+  OCMStub([self.mockConfigurator clientMode]).andReturn(SNTClientModeLockdown);
+  OCMStub([self.mockConfigurator enableMachineIDDecoration]).andReturn(YES);
+  OCMStub([self.mockConfigurator machineID]).andReturn(@"my_id");
+
+  self.testCachedDecision = [[SNTCachedDecision alloc] init];
+  self.testCachedDecision.decision = SNTEventStateAllowBinary;
+  self.testCachedDecision.decisionExtra = @"extra!";
+  self.testCachedDecision.sha256 = @"1234_hash";
+  self.testCachedDecision.quarantineURL = @"google.com";
+  self.testCachedDecision.certSHA256 = @"5678_hash";
+
+  self.mockDecisionCache = OCMClassMock([SNTDecisionCache class]);
+  OCMStub([self.mockDecisionCache sharedCache]).andReturn(self.mockDecisionCache);
+  OCMStub([self.mockDecisionCache cachedDecisionForFile:{}])
+    .ignoringNonObjectArgs()
+    .andReturn(self.testCachedDecision);
+}
+
+- (void)tearDown {
+  [self.mockConfigurator stopMocking];
+  [self.mockDecisionCache stopMocking];
+}
+
+- (void)testSerializeMessageClose {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_file_t file = MakeESFile("close_file");
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_CLOSE, &proc);
+  esMsg.event.close.modified = true;
+  esMsg.event.close.target = &file;
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=WRITE|path=close_file"
+                     "|pid=12|ppid=56|process=foo|processpath=foo"
+                     "|uid=-2|user=nobody|gid=-2|group=nobody\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageExchange {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_file_t file1 = MakeESFile("exchange_1");
+  es_file_t file2 = MakeESFile("exchange_2");
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXCHANGEDATA, &proc);
+  esMsg.event.exchangedata.file1 = &file1;
+  esMsg.event.exchangedata.file2 = &file2;
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=EXCHANGE|path=exchange_1|newpath=exchange_2"
+                     "|pid=12|ppid=56|process=foo|processpath=foo"
+                     "|uid=-2|user=nobody|gid=-2|group=nobody\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageExec {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+
+  es_file_t execFile = MakeESFile("execpath|");
+  es_process_t procExec = MakeESProcess(&execFile, MakeAuditToken(12, 89), MakeAuditToken(56, 78));
+
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXEC, &proc);
+  esMsg.event.exec.target = &procExec;
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  EXPECT_CALL(*mockESApi, ExecArgCount).WillOnce(testing::Return(3));
+
+  EXPECT_CALL(*mockESApi, ExecArg)
+    .WillOnce(testing::Return(es_string_token_t{9, "exec|path"}))
+    .WillOnce(testing::Return(es_string_token_t{5, "-l\n-t"}))
+    .WillOnce(testing::Return(es_string_token_t{8, "-v\r--foo"}));
+
+  std::string got = BasicStringSerializeMessage(mockESApi, &esMsg);
+  std::string want = "action=EXEC|decision=ALLOW|reason=BINARY|explain=extra!|sha256=1234_hash|"
+                     "cert_sha256=5678_hash|cert_cn=|quarantine_url=google.com|pid=12|pidversion="
+                     "89|ppid=56|uid=-2|user=nobody|gid=-2|group=nobody|mode=L|path=execpath<pipe>|"
+                     "args=exec<pipe>path -l\\n-t -v\\r--foo|machineid=my_id\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageExit {
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_EXIT, &proc);
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=EXIT|pid=12|pidversion=34|ppid=56|uid=-2|gid=-2\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageFork {
+  es_file_t procFile = MakeESFile("foo");
+  es_file_t procChildFile = MakeESFile("foo_child");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_process_t procChild =
+    MakeESProcess(&procChildFile, MakeAuditToken(67, 89), MakeAuditToken(12, 34));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_FORK, &proc);
+  esMsg.event.fork.child = &procChild;
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=FORK|pid=67|pidversion=89|ppid=12|uid=-2|gid=-2\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageLink {
+  es_file_t procFile = MakeESFile("foo");
+  es_file_t srcFile = MakeESFile("link_src");
+  es_file_t dstDir = MakeESFile("link_dst");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_LINK, &proc);
+  esMsg.event.link.source = &srcFile;
+  esMsg.event.link.target_dir = &dstDir;
+  esMsg.event.link.target_filename = MakeESStringToken("link_name");
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=LINK|path=link_src|newpath=link_dst/link_name"
+                     "|pid=12|ppid=56|process=foo|processpath=foo"
+                     "|uid=-2|user=nobody|gid=-2|group=nobody\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageRename {
+  es_file_t procFile = MakeESFile("foo");
+  es_file_t srcFile = MakeESFile("rename_src");
+  es_file_t dstFile = MakeESFile("rename_dst");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_RENAME, &proc);
+  esMsg.event.rename.source = &srcFile;
+  esMsg.event.rename.destination_type = ES_DESTINATION_TYPE_EXISTING_FILE;
+  esMsg.event.rename.destination.existing_file = &dstFile;
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=RENAME|path=rename_src|newpath=rename_dst"
+                     "|pid=12|ppid=56|process=foo|processpath=foo"
+                     "|uid=-2|user=nobody|gid=-2|group=nobody\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeMessageUnlink {
+  es_file_t procFile = MakeESFile("foo");
+  es_file_t targetFile = MakeESFile("deleted_file");
+  es_process_t proc = MakeESProcess(&procFile, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_UNLINK, &proc);
+  esMsg.event.unlink.target = &targetFile;
+
+  std::string got = BasicStringSerializeMessage(&esMsg);
+  std::string want = "action=DELETE|path=deleted_file"
+                     "|pid=12|ppid=56|process=foo|processpath=foo"
+                     "|uid=-2|user=nobody|gid=-2|group=nobody\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeAllowlist {
+  es_file_t file = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&file, MakeAuditToken(12, 34), MakeAuditToken(56, 78));
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_CLOSE, &proc);
+  esMsg.event.close.target = &file;
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  std::vector<uint8_t> ret = BasicString::Create(mockESApi, false)
+                               ->SerializeAllowlist(Message(mockESApi, &esMsg), "test_hash");
+
+  XCTAssertTrue(testing::Mock::VerifyAndClearExpectations(mockESApi.get()),
+                "Expected calls were not properly mocked");
+
+  std::string got(ret.begin(), ret.end());
+  std::string want = "action=ALLOWLIST|pid=12|pidversion=34|path=foo"
+                     "|sha256=test_hash\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeBundleHashingEvent {
+  SNTStoredEvent *se = [[SNTStoredEvent alloc] init];
+
+  se.fileSHA256 = @"file_hash";
+  se.fileBundleHash = @"file_bundle_hash";
+  se.fileBundleName = @"file_bundle_Name";
+  se.fileBundleID = nil;
+  se.fileBundlePath = @"file_bundle_path";
+  se.filePath = @"file_path";
+
+  std::vector<uint8_t> ret = BasicString::Create(nullptr, false)->SerializeBundleHashingEvent(se);
+  std::string got(ret.begin(), ret.end());
+
+  std::string want = "action=BUNDLE|sha256=file_hash"
+                     "|bundlehash=file_bundle_hash|bundlename=file_bundle_Name|bundleid="
+                     "|bundlepath=file_bundle_path|path=file_path\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeDiskAppeared {
+  NSDictionary *props = @{
+    @"DADevicePath" : @"",
+    @"DADeviceVendor" : @"vendor",
+    @"DADeviceModel" : @"model",
+    @"DAAppearanceTime" : @(1252487349),  // 2009-09-09 09:09:09
+    @"DAVolumePath" : [NSURL URLWithString:@"path"],
+    @"DAMediaBSDName" : @"bsd",
+    @"DAVolumeKind" : @"apfs",
+    @"DADeviceProtocol" : @"usb",
+  };
+
+  std::vector<uint8_t> ret = BasicString::Create(nullptr, false)->SerializeDiskAppeared(props);
+  std::string got(ret.begin(), ret.end());
+
+  std::string want = "action=DISKAPPEAR|mount=path|volume=|bsdname=bsd|fs=apfs"
+                     "|model=vendor model|serial=|bus=usb|dmgpath="
+                     "|appearance=2040-09-09T09:09:09.000Z\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testSerializeDiskDisappeared {
+  NSDictionary *props = @{
+    @"DAVolumePath" : [NSURL URLWithString:@"path"],
+    @"DAMediaBSDName" : @"bsd",
+  };
+
+  std::vector<uint8_t> ret = BasicString::Create(nullptr, false)->SerializeDiskDisappeared(props);
+  std::string got(ret.begin(), ret.end());
+
+  std::string want = "action=DISKDISAPPEAR|mount=path|volume=|bsdname=bsd\n";
+
+  XCTAssertCppStringEqual(got, want);
+}
+
+- (void)testGetDecisionString {
+  std::map<SNTEventState, std::string> stateToDecision = {
+    {SNTEventStateUnknown, "UNKNOWN"},
+    {SNTEventStateBundleBinary, "UNKNOWN"},
+    {SNTEventStateBlockUnknown, "DENY"},
+    {SNTEventStateBlockBinary, "DENY"},
+    {SNTEventStateBlockCertificate, "DENY"},
+    {SNTEventStateBlockScope, "DENY"},
+    {SNTEventStateBlockTeamID, "DENY"},
+    {SNTEventStateBlockLongPath, "DENY"},
+    {SNTEventStateAllowUnknown, "ALLOW"},
+    {SNTEventStateAllowBinary, "ALLOW"},
+    {SNTEventStateAllowCertificate, "ALLOW"},
+    {SNTEventStateAllowScope, "ALLOW"},
+    {SNTEventStateAllowCompiler, "ALLOW"},
+    {SNTEventStateAllowTransitive, "ALLOW"},
+    {SNTEventStateAllowPendingTransitive, "ALLOW"},
+    {SNTEventStateAllowTeamID, "ALLOW"},
+  };
+
+  for (const auto &kv : stateToDecision) {
+    XCTAssertCppStringEqual(GetDecisionString(kv.first), kv.second);
+  }
+}
+
+- (void)testGetReasonString {
+  std::map<SNTEventState, std::string> stateToReason = {
+    {SNTEventStateUnknown, "NOTRUNNING"},
+    {SNTEventStateBundleBinary, "NOTRUNNING"},
+    {SNTEventStateBlockUnknown, "UNKNOWN"},
+    {SNTEventStateBlockBinary, "BINARY"},
+    {SNTEventStateBlockCertificate, "CERT"},
+    {SNTEventStateBlockScope, "SCOPE"},
+    {SNTEventStateBlockTeamID, "TEAMID"},
+    {SNTEventStateBlockLongPath, "LONG_PATH"},
+    {SNTEventStateAllowUnknown, "UNKNOWN"},
+    {SNTEventStateAllowBinary, "BINARY"},
+    {SNTEventStateAllowCertificate, "CERT"},
+    {SNTEventStateAllowScope, "SCOPE"},
+    {SNTEventStateAllowCompiler, "COMPILER"},
+    {SNTEventStateAllowTransitive, "TRANSITIVE"},
+    {SNTEventStateAllowPendingTransitive, "PENDING_TRANSITIVE"},
+    {SNTEventStateAllowTeamID, "TEAMID"},
+  };
+
+  for (const auto &kv : stateToReason) {
+    XCTAssertCppStringEqual(GetReasonString(kv.first), kv.second);
+  }
+}
+
+- (void)testGetModeString {
+  std::map<SNTClientMode, std::string> modeToString = {
+    {SNTClientModeMonitor, "M"},
+    {SNTClientModeLockdown, "L"},
+    {(SNTClientMode)123, "U"},
+  };
+
+  for (const auto &kv : modeToString) {
+    XCTAssertCppStringEqual(GetModeString(kv.first), kv.second);
+  }
+}
+
+- (void)testGetAllowListTargetFile {
+  es_file_t closeTargetFile = MakeESFile("close_target");
+  es_file_t renameSourceFile = MakeESFile("rename_source");
+  es_file_t procFile = MakeESFile("foo");
+  es_process_t proc = MakeESProcess(&procFile);
+  es_message_t esMsg = MakeESMessage(ES_EVENT_TYPE_NOTIFY_CLOSE, &proc);
+
+  auto mockESApi = std::make_shared<MockEndpointSecurityAPI>();
+  mockESApi->SetExpectationsRetainReleaseMessage(&esMsg);
+
+  {
+    esMsg.event.close.target = &closeTargetFile;
+    Message msg(mockESApi, &esMsg);
+    es_file_t *target = GetAllowListTargetFile(msg);
+    XCTAssertEqual(target, &closeTargetFile);
+  }
+
+  {
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_RENAME;
+    esMsg.event.rename.source = &renameSourceFile;
+    Message msg(mockESApi, &esMsg);
+    es_file_t *target = GetAllowListTargetFile(msg);
+    XCTAssertEqual(target, &renameSourceFile);
+  }
+
+  {
+    esMsg.event_type = ES_EVENT_TYPE_NOTIFY_EXIT;
+    Message msg(mockESApi, &esMsg);
+    XCTAssertThrows(GetAllowListTargetFile(msg));
+  }
+}
+
+@end

Source/santad/Logs/EndpointSecurity/Serializers/Empty.h

@@ -0,0 +1,60 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_EMPTY_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_EMPTY_H
+
+#import <Foundation/Foundation.h>
+
+#include <memory>
+#include <vector>
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+class Empty : public Serializer {
+ public:
+  static std::shared_ptr<Empty> Create();
+
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedClose &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExchange &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExec &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExit &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedFork &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedLink &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedRename &) override;
+  std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedUnlink &) override;
+
+  std::vector<uint8_t> SerializeAllowlist(
+    const santa::santad::event_providers::endpoint_security::Message &,
+    const std::string_view) override;
+
+  std::vector<uint8_t> SerializeBundleHashingEvent(SNTStoredEvent *) override;
+
+  std::vector<uint8_t> SerializeDiskAppeared(NSDictionary *) override;
+  std::vector<uint8_t> SerializeDiskDisappeared(NSDictionary *) override;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::serializers
+
+#endif

Source/santad/Logs/EndpointSecurity/Serializers/Empty.mm

@@ -0,0 +1,81 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Empty.h"
+
+using santa::santad::event_providers::endpoint_security::EnrichedClose;
+using santa::santad::event_providers::endpoint_security::EnrichedExchange;
+using santa::santad::event_providers::endpoint_security::EnrichedExec;
+using santa::santad::event_providers::endpoint_security::EnrichedExit;
+using santa::santad::event_providers::endpoint_security::EnrichedFork;
+using santa::santad::event_providers::endpoint_security::EnrichedLink;
+using santa::santad::event_providers::endpoint_security::EnrichedRename;
+using santa::santad::event_providers::endpoint_security::EnrichedUnlink;
+using santa::santad::event_providers::endpoint_security::Message;
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+std::shared_ptr<Empty> Empty::Create() {
+  return std::make_shared<Empty>();
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedClose &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedExchange &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedExec &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedExit &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedFork &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedLink &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedRename &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeMessage(const EnrichedUnlink &msg) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeAllowlist(const Message &msg, const std::string_view hash) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeBundleHashingEvent(SNTStoredEvent *event) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeDiskAppeared(NSDictionary *props) {
+  return {};
+}
+
+std::vector<uint8_t> Empty::SerializeDiskDisappeared(NSDictionary *props) {
+  return {};
+}
+
+}  // namespace santa::santad::logs::endpoint_security::serializers

Source/santad/Logs/EndpointSecurity/Serializers/EmptyTest.mm

@@ -0,0 +1,53 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <Foundation/Foundation.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Empty.h"
+
+using santa::santad::logs::endpoint_security::serializers::Empty;
+
+namespace es = santa::santad::event_providers::endpoint_security;
+
+@interface EmptyTest : XCTestCase
+@end
+
+@implementation EmptyTest
+
+- (void)testAllSerializersReturnEmptyVector {
+  std::shared_ptr<Empty> e = Empty::Create();
+
+  // We can get away with passing a fake argument to the `Serialize*` methods
+  // instead of constructing real ones since the Empty class never touches the
+  // input parameter.
+  int fake;
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedClose *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedExchange *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedExec *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedExit *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedFork *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedLink *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedRename *)&fake).size(), 0);
+  XCTAssertEqual(e->SerializeMessage(*(es::EnrichedUnlink *)&fake).size(), 0);
+
+  XCTAssertEqual(e->SerializeAllowlist(*(es::Message *)&fake, "").size(), 0);
+  XCTAssertEqual(e->SerializeBundleHashingEvent(nil).size(), 0);
+  XCTAssertEqual(e->SerializeDiskAppeared(nil).size(), 0);
+  XCTAssertEqual(e->SerializeDiskDisappeared(nil).size(), 0);
+}
+
+@end

Source/santad/Logs/EndpointSecurity/Serializers/SanitizableString.h

@@ -0,0 +1,62 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_SANITIZABLESTRING_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_SANITIZABLESTRING_H
+
+#include <EndpointSecurity/EndpointSecurity.h>
+#import <Foundation/Foundation.h>
+
+#include <optional>
+#include <sstream>
+#include <string>
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+// Small helper class that will sanitize a given string, but will only use new
+// memory if the string required sanitization. If the string is already
+// sanitized, this class only uses the given buffers.
+class SanitizableString {
+ public:
+  SanitizableString(const es_file_t *file);
+  SanitizableString(const es_string_token_t &tok);
+  SanitizableString(const char *str, size_t len);
+  SanitizableString(NSString *str);
+
+  SanitizableString(SanitizableString &&other) = delete;
+  SanitizableString(const SanitizableString &other) = delete;
+  SanitizableString &operator=(const SanitizableString &rhs) = delete;
+  SanitizableString &operator=(SanitizableString &&rhs) = delete;
+
+  // Return the original, unsanitized string
+  std::string_view String() const;
+
+  // Return the sanitized string
+  std::string_view Sanitized() const;
+
+  static std::optional<std::string> SanitizeString(const char *str);
+  static std::optional<std::string> SanitizeString(const char *str, size_t length);
+
+  friend std::ostream &operator<<(std::ostream &ss, const SanitizableString &sani_string);
+
+ private:
+  const char *data_;
+  size_t length_;
+  mutable bool sanitized_ = false;
+  mutable std::optional<std::string> sanitized_string_;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::serializers
+
+#endif

Source/santad/Logs/EndpointSecurity/Serializers/SanitizableString.mm

@@ -0,0 +1,113 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/SanitizableString.h"
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+SanitizableString::SanitizableString(const es_file_t *file)
+    : data_(file->path.data), length_(file->path.length) {}
+
+SanitizableString::SanitizableString(const es_string_token_t &tok)
+    : data_(tok.data), length_(tok.length) {}
+
+SanitizableString::SanitizableString(NSString *str)
+    : data_([str UTF8String]), length_([str length]) {}
+
+SanitizableString::SanitizableString(const char *str, size_t len) : data_(str), length_(len) {}
+
+std::string_view SanitizableString::String() const {
+  return std::string_view(data_, length_);
+}
+
+std::string_view SanitizableString::Sanitized() const {
+  if (!sanitized_) {
+    sanitized_ = true;
+    sanitized_string_ = SanitizeString(data_, length_);
+  }
+
+  if (sanitized_string_.has_value()) {
+    return sanitized_string_.value();
+  } else {
+    if (data_) {
+      return std::string_view(data_, length_);
+    } else {
+      return "";
+    }
+  }
+}
+
+std::ostream &operator<<(std::ostream &ss, const SanitizableString &sani_string) {
+  ss << sani_string.Sanitized();
+  return ss;
+}
+
+std::optional<std::string> SanitizableString::SanitizeString(const char *str) {
+  return SanitizeString(str, str ? strlen(str) : 0);
+}
+
+std::optional<std::string> SanitizableString::SanitizeString(const char *str, size_t length) {
+  size_t strOffset = 0;
+  char c = 0;
+  std::string buf;
+  bool reservedStringSpace = false;
+
+  if (!str) {
+    return std::nullopt;
+  }
+
+  if (length < 1) {
+    return std::nullopt;
+  }
+
+  // Loop through the string one character at a time, looking for the characters
+  // we want to remove.
+  for (const char *p = str; (c = *p) != 0; ++p) {
+    if (c == '|' || c == '\n' || c == '\r') {
+      if (!reservedStringSpace) {
+        // Assume the common case won't grow the string length by more than a
+        // factor of 2. String will grow more if it needs to.
+        buf.reserve(length * 2);
+        reservedStringSpace = true;
+      }
+
+      // Copy from the last offset up to the character we just found into the buffer
+      ptrdiff_t diff = p - str;
+      buf.append(str + strOffset, diff - strOffset);
+
+      // Update the buffer and string offsets
+      strOffset = diff + 1;
+
+      // Replace the found character and advance the buffer offset
+      switch (c) {
+        case '|': buf.append("<pipe>"); break;
+        case '\n': buf.append("\\n"); break;
+        case '\r': buf.append("\\r"); break;
+      }
+    }
+  }
+
+  if (strOffset > 0 && strOffset < length) {
+    // Copy any characters from the last match to the end of the string into the buffer.
+    buf.append(str + strOffset, length - strOffset);
+  }
+
+  if (reservedStringSpace) {
+    return buf;
+  }
+
+  return std::nullopt;
+}
+
+}  // namespace santa::santad::logs::endpoint_security::serializers

Source/santad/Logs/EndpointSecurity/Serializers/SanitizableStringTest.mm

@@ -0,0 +1,90 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/SanitizableString.h"
+
+#include <EndpointSecurity/ESTypes.h>
+#import <OCMock/OCMock.h>
+#import <XCTest/XCTest.h>
+#include <sstream>
+#include <string_view>
+
+#include "Source/common/TestUtils.h"
+
+using santa::santad::logs::endpoint_security::serializers::SanitizableString;
+
+@interface SanitizableStringTest : XCTestCase
+@end
+
+@implementation SanitizableStringTest
+
+- (void)testSanitizeString {
+  const char *empty = "";
+  size_t emptyLen = strlen(empty);
+  const char *noSanitize = "nothing_to_sanitize";
+  size_t noSanitizeLen = strlen(noSanitize);
+  const char *sanitizable = "sani|tizable";
+  size_t sanitizableLen = strlen(sanitizable);
+
+  // NULL pointers are handled
+  XCTAssertFalse(SanitizableString::SanitizeString(NULL).has_value());
+
+  // Non-sanitized strings return std::nullopt
+  XCTAssertEqual(std::nullopt, SanitizableString::SanitizeString(empty));
+  XCTAssertEqual(std::nullopt, SanitizableString::SanitizeString(noSanitize));
+
+  // Intentional pointer compare to ensure the data member of the returned
+  // string_view matches the original buffer when not sanitized, and not equal
+  // when the string needs sanitization
+  XCTAssertEqual(empty, SanitizableString(empty, emptyLen).Sanitized().data());
+  XCTAssertEqual(noSanitize, SanitizableString(noSanitize, noSanitizeLen).Sanitized().data());
+  XCTAssertNotEqual(sanitizable, SanitizableString(sanitizable, sanitizableLen).Sanitized().data());
+
+  // Ensure the `String` method always returns the unsanitized buffer
+  XCTAssertEqual(empty, SanitizableString(empty, emptyLen).String().data());
+  XCTAssertEqual(noSanitize, SanitizableString(noSanitize, noSanitizeLen).String().data());
+  XCTAssertEqual(sanitizable, SanitizableString(sanitizable, sanitizableLen).String().data());
+
+  XCTAssertCStringEqual(SanitizableString(@"|").Sanitized().data(), "<pipe>");
+  XCTAssertCStringEqual(SanitizableString(@"\n").Sanitized().data(), "\\n");
+  XCTAssertCStringEqual(SanitizableString(@"\r").Sanitized().data(), "\\r");
+
+  XCTAssertCStringEqual(SanitizableString(@"a\nb\rc|").Sanitized().data(), "a\\nb\\rc<pipe>");
+  XCTAssertCStringEqual(SanitizableString(@"a|trail").Sanitized().data(), "a<pipe>trail");
+
+  // Handle some long strings
+  NSString *base = [NSString stringWithFormat:@"%@|abc", [@"" stringByPaddingToLength:66 * 1024
+                                                                           withString:@"A"
+                                                                      startingAtIndex:0]];
+
+  NSString *want = [NSString stringWithFormat:@"%@<pipe>abc", [@"" stringByPaddingToLength:66 * 1024
+                                                                                withString:@"A"
+                                                                           startingAtIndex:0]];
+
+  XCTAssertCStringEqual(SanitizableString(base).Sanitized().data(), [want UTF8String]);
+}
+
+- (void)testStream {
+  // Test that using the `<<` operator will sanitize the string
+  std::ostringstream ss;
+  const char *sanitizable = "sani|tizable";
+  const char *sanitized = "sani<pipe>tizable";
+  es_string_token_t tok = {.length = strlen(sanitizable), .data = sanitizable};
+
+  ss << SanitizableString(tok);
+
+  XCTAssertCStringEqual(ss.str().c_str(), sanitized);
+}
+
+@end

Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h

@@ -0,0 +1,87 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_SERIALIZER_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_SERIALIZERS_SERIALIZER_H
+
+#include <memory>
+#include <vector>
+
+#import <Foundation/Foundation.h>
+
+#include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
+
+@class SNTStoredEvent;
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+class Serializer {
+ public:
+  virtual ~Serializer() = default;
+
+  std::vector<uint8_t> SerializeMessage(
+    std::shared_ptr<santa::santad::event_providers::endpoint_security::EnrichedMessage> msg) {
+    return std::visit([this](const auto &arg) { return this->SerializeMessageTemplate(arg); },
+                      msg->GetEnrichedMessage());
+  }
+
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedClose &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExchange &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExec &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedExit &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedFork &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedLink &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedRename &) = 0;
+  virtual std::vector<uint8_t> SerializeMessage(
+    const santa::santad::event_providers::endpoint_security::EnrichedUnlink &) = 0;
+
+  virtual std::vector<uint8_t> SerializeAllowlist(
+    const santa::santad::event_providers::endpoint_security::Message &, const std::string_view) = 0;
+
+  virtual std::vector<uint8_t> SerializeBundleHashingEvent(SNTStoredEvent *) = 0;
+
+  virtual std::vector<uint8_t> SerializeDiskAppeared(NSDictionary *) = 0;
+  virtual std::vector<uint8_t> SerializeDiskDisappeared(NSDictionary *) = 0;
+
+ private:
+  // Template methods used to ensure a place to implement any desired
+  // functionality that shouldn't be overridden by derived classes.
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedClose &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedExchange &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedExec &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedExit &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedFork &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedLink &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedRename &);
+  std::vector<uint8_t> SerializeMessageTemplate(
+    const santa::santad::event_providers::endpoint_security::EnrichedUnlink &);
+};
+
+}  // namespace santa::santad::logs::endpoint_security::serializers
+
+#endif

Source/santad/Logs/EndpointSecurity/Serializers/Serializer.mm

@@ -0,0 +1,58 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#include "Source/santad/Logs/EndpointSecurity/Serializers/Serializer.h"
+
+#include <EndpointSecurity/EndpointSecurity.h>
+
+#import "Source/santad/SNTDecisionCache.h"
+
+namespace es = santa::santad::event_providers::endpoint_security;
+
+namespace santa::santad::logs::endpoint_security::serializers {
+
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedClose &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedExchange &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedExec &msg) {
+  const es_message_t &es_msg = msg.es_msg();
+  if (es_msg.action_type == ES_ACTION_TYPE_NOTIFY &&
+      es_msg.action.notify.result.auth == ES_AUTH_RESULT_ALLOW) {
+    // For allowed execs, cached decision timestamps must be updated
+    [[SNTDecisionCache sharedCache]
+      resetTimestampForCachedDecision:msg.es_msg().event.exec.target->executable->stat];
+  }
+
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedExit &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedFork &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedLink &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedRename &msg) {
+  return SerializeMessage(msg);
+}
+std::vector<uint8_t> Serializer::SerializeMessageTemplate(const es::EnrichedUnlink &msg) {
+  return SerializeMessage(msg);
+}
+
+};  // namespace santa::santad::logs::endpoint_security::serializers

Source/santad/Logs/EndpointSecurity/Writers/File.h

@@ -0,0 +1,64 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_FILE_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_FILE_H
+
+#include "Source/santad/Logs/EndpointSecurity/Writers/Writer.h"
+
+#include <Foundation/Foundation.h>
+#include <dispatch/dispatch.h>
+
+#include <memory>
+#include <vector>
+
+// Forward declarations
+namespace santa::santad::logs::endpoint_security::writers {
+class FilePeer;
+}
+
+namespace santa::santad::logs::endpoint_security::writers {
+
+class File : public Writer, public std::enable_shared_from_this<File> {
+ public:
+  // Factory
+  static std::shared_ptr<File> Create(NSString *path, uint64_t flush_timeout_ms,
+                                      size_t batch_size_bytes,
+                                      size_t max_expected_write_size_bytes);
+
+  File(NSString *path, size_t batch_size_bytes, size_t max_expected_write_size_bytes,
+       dispatch_queue_t q, dispatch_source_t timer_source);
+  ~File();
+
+  void Write(std::vector<uint8_t> &&bytes) override;
+
+  friend class santa::santad::logs::endpoint_security::writers::FilePeer;
+
+ private:
+  void OpenFileHandle();
+  void WatchLogFile();
+  void FlushBuffer();
+
+  std::vector<uint8_t> buffer_;
+  size_t batch_size_bytes_;
+  dispatch_queue_t q_;
+  dispatch_source_t timer_source_;
+  dispatch_source_t watch_source_;
+  NSString *path_;
+  NSFileHandle *file_handle_;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::writers
+
+#endif

Source/santad/Logs/EndpointSecurity/Writers/File.mm

@@ -0,0 +1,115 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import "Source/santad/Logs/EndpointSecurity/Writers/File.h"
+
+#include <memory>
+
+namespace santa::santad::logs::endpoint_security::writers {
+
+std::shared_ptr<File> File::Create(NSString *path, uint64_t flush_timeout_ms,
+                                   size_t batch_size_bytes, size_t max_expected_write_size_bytes) {
+  dispatch_queue_t q = dispatch_queue_create("com.google.santa.daemon.file_event_log",
+                                             DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL);
+  dispatch_source_t timer_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, q);
+
+  dispatch_source_set_timer(timer_source, dispatch_time(DISPATCH_TIME_NOW, 0),
+                            NSEC_PER_MSEC * flush_timeout_ms, 0);
+
+  auto ret_writer =
+    std::make_shared<File>(path, batch_size_bytes, max_expected_write_size_bytes, q, timer_source);
+  ret_writer->WatchLogFile();
+
+  std::weak_ptr<File> weak_writer(ret_writer);
+  dispatch_source_set_event_handler(ret_writer->timer_source_, ^{
+    std::shared_ptr<File> shared_writer = weak_writer.lock();
+    if (!shared_writer) {
+      return;
+    }
+    shared_writer->FlushBuffer();
+  });
+
+  dispatch_resume(ret_writer->timer_source_);
+
+  return ret_writer;
+}
+
+File::File(NSString *path, size_t batch_size_bytes, size_t max_expected_write_size_bytes,
+           dispatch_queue_t q, dispatch_source_t timer_source)
+    : batch_size_bytes_(batch_size_bytes),
+      q_(q),
+      timer_source_(timer_source),
+      watch_source_(nullptr) {
+  path_ = path;
+  buffer_.reserve(batch_size_bytes + max_expected_write_size_bytes);
+  OpenFileHandle();
+}
+
+void File::WatchLogFile() {
+  if (watch_source_) {
+    dispatch_source_cancel(watch_source_);
+  }
+
+  watch_source_ = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, file_handle_.fileDescriptor,
+                                         DISPATCH_VNODE_DELETE | DISPATCH_VNODE_RENAME, q_);
+
+  auto shared_this = shared_from_this();
+  dispatch_source_set_event_handler(watch_source_, ^{
+    [shared_this->file_handle_ closeFile];
+    shared_this->OpenFileHandle();
+    shared_this->WatchLogFile();
+  });
+
+  dispatch_resume(watch_source_);
+}
+
+File::~File() {
+  if (timer_source_) {
+    dispatch_source_cancel(timer_source_);
+  }
+}
+
+// IMPORTANT: Not thread safe.
+void File::OpenFileHandle() {
+  NSFileManager *fm = [NSFileManager defaultManager];
+  if (![fm fileExistsAtPath:path_]) {
+    [fm createFileAtPath:path_ contents:nil attributes:nil];
+  }
+  file_handle_ = [NSFileHandle fileHandleForWritingAtPath:path_];
+  [file_handle_ seekToEndOfFile];
+}
+
+void File::Write(std::vector<uint8_t> &&bytes) {
+  auto shared_this = shared_from_this();
+
+  // Workaround to move `bytes` into the block without a copy
+  __block std::vector<uint8_t> temp_bytes = std::move(bytes);
+
+  dispatch_async(q_, ^{
+    std::vector<uint8_t> moved_bytes = std::move(temp_bytes);
+
+    shared_this->buffer_.insert(shared_this->buffer_.end(), moved_bytes.begin(), moved_bytes.end());
+    if (shared_this->buffer_.size() >= batch_size_bytes_) {
+      shared_this->FlushBuffer();
+    }
+  });
+}
+
+// IMPORTANT: Not thread safe.
+void File::FlushBuffer() {
+  write(file_handle_.fileDescriptor, buffer_.data(), buffer_.size());
+  buffer_.clear();
+}
+
+}  // namespace santa::santad::logs::endpoint_security::writers

Source/santad/Logs/EndpointSecurity/Writers/FileTest.mm

@@ -0,0 +1,179 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#import <Foundation/Foundation.h>
+#include <dispatch/dispatch.h>
+#include <gtest/gtest.h>
+#include <sys/stat.h>
+
+#include <vector>
+
+#include "Source/common/TestUtils.h"
+#import "Source/santad/Logs/EndpointSecurity/Writers/File.h"
+
+namespace santa::santad::logs::endpoint_security::writers {
+
+class FilePeer : public File {
+ public:
+  // Make constructors visible
+  using File::File;
+
+  NSFileHandle *FileHandle() { return file_handle_; }
+
+  void BeginWatchingLogFile() { WatchLogFile(); }
+
+  size_t InternalBufferSize() { return buffer_.size(); }
+};
+
+}  // namespace santa::santad::logs::endpoint_security::writers
+
+using santa::santad::logs::endpoint_security::writers::FilePeer;
+
+bool WaitFor(bool (^condition)(void)) {
+  int attempts = 0;
+  long sleepPerAttemptMS = 10;  // Wait 10ms between checks
+  long maxSleep = 2000;         // Wait up to 2 seconds for new log file to be created
+  long maxAttempts = maxSleep / sleepPerAttemptMS;
+
+  do {
+    SleepMS(sleepPerAttemptMS);
+
+    // Break out once the condition holds
+    if (condition()) {
+      break;
+    }
+  } while (++attempts < maxAttempts);
+
+  return attempts < maxAttempts;
+}
+
+bool WaitForNewLogFile(NSFileManager *fileManager, NSString *path) {
+  return WaitFor(^bool() {
+    return [fileManager fileExistsAtPath:path];
+  });
+}
+
+bool WaitForBufferSize(std::shared_ptr<FilePeer> file, size_t expectedSize) {
+  return WaitFor(^bool() {
+    return file->InternalBufferSize() == expectedSize;
+  });
+}
+
+@interface FileTest : XCTestCase
+@property NSString *path;
+@property NSString *logPath;
+@property NSString *logRenamePath;
+@property dispatch_queue_t q;
+@property dispatch_source_t timer;
+@property NSFileManager *fileManager;
+@end
+
+@implementation FileTest
+
+- (void)setUp {
+  self.path = [NSString stringWithFormat:@"%@santa-%d", NSTemporaryDirectory(), getpid()];
+
+  self.logPath = [NSString stringWithFormat:@"%@/log.out", self.path];
+  self.logRenamePath = [NSString stringWithFormat:@"%@/log.rename.out", self.path];
+
+  self.fileManager = [NSFileManager defaultManager];
+
+  XCTAssertTrue([self.fileManager createDirectoryAtPath:self.path
+                            withIntermediateDirectories:YES
+                                             attributes:nil
+                                                  error:nil]);
+
+  self.q = dispatch_queue_create(NULL, DISPATCH_QUEUE_SERIAL);
+  XCTAssertNotNil(self.q);
+  self.timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, self.q);
+  XCTAssertNotNil(self.timer);
+
+  // Resume the timer to ensure its not inadvertently cancelled first
+  dispatch_resume(self.timer);
+}
+
+- (void)tearDown {
+  [self.fileManager removeItemAtPath:self.path error:nil];
+}
+
+- (void)testWatchLogFile {
+  auto file = std::make_shared<FilePeer>(self.logPath, 100, 500, self.q, self.timer);
+  file->BeginWatchingLogFile();
+
+  // Constructing a File object will open the file at the given path
+  struct stat wantSBOrig;
+  struct stat gotSBOrig;
+  XCTAssertEqual(stat([self.logPath UTF8String], &wantSBOrig), 0);
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSBOrig), 0);
+  XCTAssertEqual(wantSBOrig.st_ino, gotSBOrig.st_ino);
+
+  // Deleting the current log file will cause a new file to be created
+  XCTAssertTrue([self.fileManager removeItemAtPath:self.logPath error:nil]);
+
+  XCTAssertTrue(WaitForNewLogFile(self.fileManager, self.logPath),
+                "New log file not created within expected time after deletion");
+
+  struct stat wantSBAfterDelete;
+  struct stat gotSBAfterDelete;
+  XCTAssertEqual(stat([self.logPath UTF8String], &wantSBAfterDelete), 0);
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSBAfterDelete), 0);
+
+  XCTAssertEqual(wantSBAfterDelete.st_ino, gotSBAfterDelete.st_ino);
+  XCTAssertNotEqual(wantSBOrig.st_ino, wantSBAfterDelete.st_ino);
+
+  // Renaming the current log file will cause a new file to be created
+  XCTAssertTrue([self.fileManager moveItemAtPath:self.logPath toPath:self.logRenamePath error:nil]);
+
+  XCTAssertTrue(WaitForNewLogFile(self.fileManager, self.logPath),
+                "New log file not created within expected time after rename");
+
+  struct stat wantSBAfterRename;
+  struct stat gotSBAfterRename;
+  XCTAssertEqual(stat([self.logPath UTF8String], &wantSBAfterRename), 0);
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSBAfterRename), 0);
+
+  XCTAssertEqual(wantSBAfterRename.st_ino, gotSBAfterRename.st_ino);
+  XCTAssertNotEqual(wantSBAfterDelete.st_ino, wantSBAfterRename.st_ino);
+}
+
+- (void)testWrite {
+  // Start with empty file. Perform two writes. The first will only go into the
+  // internal buffer. The second will meet/exceed capacity and flush to disk
+  size_t bufferSize = 100;
+  size_t writeSize = 50;
+  auto file =
+    std::make_shared<FilePeer>(self.logPath, bufferSize, bufferSize * 2, self.q, self.timer);
+
+  // Starting out, file size and internal buffer are 0
+  struct stat gotSB;
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSB), 0);
+  XCTAssertEqual(0, gotSB.st_size);
+  XCTAssertEqual(0, file->InternalBufferSize());
+
+  // After the first write, the buffer is 50 bytes, but the file is still 0
+  file->Write(std::vector<uint8_t>(writeSize, 'A'));
+  WaitForBufferSize(file, 50);
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSB), 0);
+  XCTAssertEqual(0, gotSB.st_size);
+  XCTAssertEqual(50, file->InternalBufferSize());
+
+  // After the second write, the buffer is flushed. File size 100, buffer is 0.
+  file->Write(std::vector<uint8_t>(writeSize, 'B'));
+  WaitForBufferSize(file, 0);
+  XCTAssertEqual(fstat(file->FileHandle().fileDescriptor, &gotSB), 0);
+  XCTAssertEqual(100, gotSB.st_size);
+  XCTAssertEqual(0, file->InternalBufferSize());
+}
+
+@end

Source/santad/Logs/EndpointSecurity/Writers/Null.h

@@ -0,0 +1,35 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_NULL_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_NULL_H
+
+#include <memory>
+#include <vector>
+
+#include "Source/santad/Logs/EndpointSecurity/Writers/Writer.h"
+
+namespace santa::santad::logs::endpoint_security::writers {
+
+class Null : public Writer {
+ public:
+  // Factory
+  static std::shared_ptr<Null> Create();
+
+  void Write(std::vector<uint8_t>&& bytes) override;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::writers
+
+#endif

Source/santad/Logs/EndpointSecurity/Writers/Null.mm

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,10 +12,16 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#import "Source/santad/Logs/SNTEventLog.h"
+#include "Source/santad/Logs/EndpointSecurity/Writers/Null.h"
 
-@interface SNTProtobufEventLog : SNTEventLog
+namespace santa::santad::logs::endpoint_security::writers {
 
-- (void)logFileModification:(santa_message_t)message;
+std::shared_ptr<Null> Null::Create() {
+  return std::make_shared<Null>();
+}
 
-@end
+void Null::Write(std::vector<uint8_t> &&bytes) {
+  // Intentionally do nothing
+}
+
+}  // namespace santa::santad::logs::endpoint_security::writers

Source/santad/Logs/EndpointSecurity/Writers/Syslog.h

@@ -0,0 +1,33 @@
+/// Copyright 2022 Google Inc. All rights reserved.
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///    http://www.apache.org/licenses/LICENSE-2.0
+///
+///    Unless required by applicable law or agreed to in writing, software
+///    distributed under the License is distributed on an "AS IS" BASIS,
+///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+///    See the License for the specific language governing permissions and
+///    limitations under the License.
+
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_SYSLOG_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_SYSLOG_H
+
+#include <vector>
+
+#include "Source/santad/Logs/EndpointSecurity/Writers/Writer.h"
+
+namespace santa::santad::logs::endpoint_security::writers {
+
+class Syslog : public Writer {
+ public:
+  static std::shared_ptr<Syslog> Create();
+
+  void Write(std::vector<uint8_t>&& bytes) override;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::writers
+
+#endif

Source/santad/Logs/EndpointSecurity/Writers/Syslog.mm

@@ -1,4 +1,4 @@
-/// Copyright 2021 Google Inc. All rights reserved.
+/// Copyright 2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,9 +12,18 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#import <Foundation/Foundation.h>
+#include "Source/santad/Logs/EndpointSecurity/Writers/Syslog.h"
 
-#include "Source/santad/EventProviders/SNTEndpointSecurityManager.h"
+#include <os/log.h>
 
-@interface SNTCachingEndpointSecurityManager : SNTEndpointSecurityManager
-@end
+namespace santa::santad::logs::endpoint_security::writers {
+
+std::shared_ptr<Syslog> Syslog::Create() {
+  return std::make_shared<Syslog>();
+}
+
+void Syslog::Write(std::vector<uint8_t> &&bytes) {
+  os_log(OS_LOG_DEFAULT, "%{public}s", bytes.data());
+}
+
+}  // namespace santa::santad::logs::endpoint_security::writers

Source/santad/Logs/EndpointSecurity/Writers/Writer.h

@@ -1,4 +1,4 @@
-/// Copyright 2015 Google Inc. All rights reserved.
+/// Copyright 2022 Google Inc. All rights reserved.
 ///
 /// Licensed under the Apache License, Version 2.0 (the "License");
 /// you may not use this file except in compliance with the License.
@@ -12,16 +12,20 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#import <Foundation/Foundation.h>
+#ifndef SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_WRITER_H
+#define SANTA__SANTAD__LOGS_ENDPOINTSECURITY_WRITERS_WRITER_H
 
-///
-///  The main controller class for santad
-///
-@interface SNTApplication : NSObject
+#include <vector>
 
-///
-///  Begins fielding requests from the driver
-///
-- (void)start;
+namespace santa::santad::logs::endpoint_security::writers {
 
-@end
+class Writer {
+ public:
+  virtual ~Writer() = default;
+
+  virtual void Write(std::vector<uint8_t>&& bytes) = 0;
+};
+
+}  // namespace santa::santad::logs::endpoint_security::writers
+
+#endif