From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Raymond Zhao <raymondzhao@microsoft.com>
Date: Wed, 18 Aug 2021 08:24:10 -0700
Subject: extend ProcessSingleton

This patch applies Electron ProcessSingleton changes onto the Chromium
files.

This patch adds a few changes to the Chromium code:
1. It adds a parameter `program_name` to the Windows constructor, making
   the generated mutex name on the Windows-side program-dependent,
   rather than shared between all Electron applications.
2. It adds an `IsAppSandboxed` check for macOS so that
   sandboxed applications generate shorter temp paths.
3. It adds a `ChangeWindowMessageFilterEx` call to the Windows
   implementation, along with a parameter `is_app_sandboxed` in the
   constructor, to handle the case when the primary app is run with
   admin permissions.
4. It adds an `OnBrowserReady` function to allow
   `requestSingleInstanceLock` to start listening to the socket later
   in the posix implementation. This function is necessary, because
   otherwise, users calling `requestSingleInstanceLock` create a
   `ProcessSingleton` instance that tries to connect to the socket
   before the browser thread is ready.

diff --git a/chrome/browser/process_singleton.h b/chrome/browser/process_singleton.h
index 16bb3aa15a5378e8319f75f4b6b72b39177828f4..5a64220aaf1309832dc0ad543e353de67fe0a779 100644
--- a/chrome/browser/process_singleton.h
+++ b/chrome/browser/process_singleton.h
@@ -102,12 +102,19 @@ class ProcessSingleton {
       base::RepeatingCallback<bool(const base::CommandLine& command_line,
                                    const base::FilePath& current_directory)>;
 
+#if BUILDFLAG(IS_WIN)
+  ProcessSingleton(const std::string& program_name,
+                   const base::FilePath& user_data_dir,
+                   bool is_sandboxed,
+                   const NotificationCallback& notification_callback);
+#else
   ProcessSingleton(const base::FilePath& user_data_dir,
                    const NotificationCallback& notification_callback);
 
   ProcessSingleton(const ProcessSingleton&) = delete;
   ProcessSingleton& operator=(const ProcessSingleton&) = delete;
 
+#endif
   ~ProcessSingleton();
 
   // Notify another process, if available. Otherwise sets ourselves as the
@@ -118,6 +125,8 @@ class ProcessSingleton {
   // TODO(brettw): Make the implementation of this method non-platform-specific
   // by making Linux re-use the Windows implementation.
   NotifyResult NotifyOtherProcessOrCreate();
+  void StartListeningOnSocket();
+  void OnBrowserReady();
 
   // Sets ourself up as the singleton instance.  Returns true on success.  If
   // false is returned, we are not the singleton instance and the caller must
@@ -173,6 +182,8 @@ class ProcessSingleton {
 #if BUILDFLAG(IS_WIN)
   bool EscapeVirtualization(const base::FilePath& user_data_dir);
 
+  std::string program_name_; // Used for mutexName.
+  bool is_app_sandboxed_; // Whether the Electron app is sandboxed.
   HWND remote_window_;  // The HWND_MESSAGE of another browser.
   base::win::MessageWindow window_;  // The message-only window.
   bool is_virtualized_;  // Stuck inside Microsoft Softricity VM environment.
@@ -222,6 +233,8 @@ class ProcessSingleton {
   // because it posts messages between threads.
   class LinuxWatcher;
   scoped_refptr<LinuxWatcher> watcher_;
+  int sock_ = -1;
+  bool listen_on_ready_ = false;
 #endif
 
 #if BUILDFLAG(IS_MAC)
diff --git a/chrome/browser/process_singleton_posix.cc b/chrome/browser/process_singleton_posix.cc
index 22331cd6985b2aa2347fe9d4211f51634e94d0a6..be2c417c07a4206fac4a9a6c03e516fd0493c942 100644
--- a/chrome/browser/process_singleton_posix.cc
+++ b/chrome/browser/process_singleton_posix.cc
@@ -54,6 +54,7 @@
 #include <memory>
 #include <set>
 #include <string>
+#include <tuple>
 #include <type_traits>
 
 #include "base/base_paths.h"
@@ -80,6 +81,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/task/sequenced_task_runner_helpers.h"
 #include "base/task/single_thread_task_runner.h"
+#include "base/task/post_task.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
@@ -96,9 +98,11 @@
 #include "net/base/network_interfaces.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if 0
 #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
 #include "chrome/browser/ui/process_singleton_dialog_linux.h"
 #endif
+#endif
 
 #if defined(TOOLKIT_VIEWS) && \
     (BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS_LACROS))
@@ -347,6 +351,9 @@ bool SymlinkPath(const base::FilePath& target, const base::FilePath& path) {
 bool DisplayProfileInUseError(const base::FilePath& lock_path,
                               const std::string& hostname,
                               int pid) {
+  return true;
+
+#if 0
   std::u16string error = l10n_util::GetStringFUTF16(
       IDS_PROFILE_IN_USE_POSIX, base::NumberToString16(pid),
       base::ASCIIToUTF16(hostname));
@@ -366,6 +373,7 @@ bool DisplayProfileInUseError(const base::FilePath& lock_path,
 
   NOTREACHED();
   return false;
+#endif
 }
 
 bool IsChromeProcess(pid_t pid) {
@@ -406,6 +414,21 @@ bool CheckCookie(const base::FilePath& path, const base::FilePath& cookie) {
   return (cookie == ReadLink(path));
 }
 
+bool IsAppSandboxed() {
+#if BUILDFLAG(IS_MAC)
+  // NB: There is no sane API for this, we have to just guess by
+  // reading tea leaves
+  base::FilePath home_dir;
+  if (!base::PathService::Get(base::DIR_HOME, &home_dir)) {
+    return false;
+  }
+
+  return home_dir.value().find("Library/Containers") != std::string::npos;
+#else
+  return false;
+#endif  // BUILDFLAG(IS_MAC)
+}
+
 bool ConnectSocket(ScopedSocket* socket,
                    const base::FilePath& socket_path,
                    const base::FilePath& cookie_path) {
@@ -773,6 +796,10 @@ ProcessSingleton::ProcessSingleton(
 
 ProcessSingleton::~ProcessSingleton() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  // Manually free resources with IO explicitly allowed.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  watcher_ = nullptr;
+  std::ignore = socket_dir_.Delete();
 }
 
 ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcess() {
@@ -945,6 +972,20 @@ ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessOrCreate() {
       base::Seconds(kTimeoutInSeconds));
 }
 
+void ProcessSingleton::StartListeningOnSocket() {
+  watcher_ = base::MakeRefCounted<LinuxWatcher>(this);
+  base::PostTask(FROM_HERE, {BrowserThread::IO},
+                 base::BindOnce(&ProcessSingleton::LinuxWatcher::StartListening,
+                                watcher_, sock_));
+}
+
+void ProcessSingleton::OnBrowserReady() {
+  if (listen_on_ready_) {
+    StartListeningOnSocket();
+    listen_on_ready_ = false;
+  }
+}
+
 ProcessSingleton::NotifyResult
 ProcessSingleton::NotifyOtherProcessWithTimeoutOrCreate(
     const base::CommandLine& command_line,
@@ -1044,14 +1085,32 @@ bool ProcessSingleton::Create() {
 #endif
   }
 
-  // Create the socket file somewhere in /tmp which is usually mounted as a
-  // normal filesystem. Some network filesystems (notably AFS) are screwy and
-  // do not support Unix domain sockets.
-  if (!socket_dir_.CreateUniqueTempDir()) {
-    LOG(ERROR) << "Failed to create socket directory.";
+  base::FilePath tmp_dir;
+  if (!base::GetTempDir(&tmp_dir)) {
+    LOG(ERROR) << "Failed to get temporary directory.";
     return false;
   }
 
+  if (IsAppSandboxed()) {
+    // For sandboxed applications, the tmp dir could be too long to fit
+    // addr->sun_path, so we need to make it as short as possible.
+    if (!socket_dir_.Set(tmp_dir.Append("S"))) {
+      LOG(ERROR) << "Failed to set socket directory.";
+      return false;
+    }
+  } else {
+    // Create the socket file somewhere in /tmp which is usually mounted as a
+    // normal filesystem. Some network filesystems (notably AFS) are screwy and
+    // do not support Unix domain sockets.
+    // Prefer CreateUniqueTempDirUnderPath rather than CreateUniqueTempDir as
+    // the latter will calculate unique paths based on bundle ids which can
+    // increase the socket path length than what is allowed.
+    if (!socket_dir_.CreateUniqueTempDirUnderPath(tmp_dir)) {
+      LOG(ERROR) << "Failed to create socket directory.";
+      return false;
+    }
+  }
+
   // Check that the directory was created with the correct permissions.
   int dir_mode = 0;
   CHECK(base::GetPosixFilePermissions(socket_dir_.GetPath(), &dir_mode) &&
@@ -1094,10 +1153,13 @@ bool ProcessSingleton::Create() {
   if (listen(sock, 5) < 0)
     NOTREACHED() << "listen failed: " << base::safe_strerror(errno);
 
-  DCHECK(BrowserThread::IsThreadInitialized(BrowserThread::IO));
-  content::GetIOThreadTaskRunner({})->PostTask(
-      FROM_HERE, base::BindOnce(&ProcessSingleton::LinuxWatcher::StartListening,
-                                watcher_, sock));
+  sock_ = sock;
+
+  if (BrowserThread::IsThreadInitialized(BrowserThread::IO)) {
+    StartListeningOnSocket();
+  } else {
+    listen_on_ready_ = true;
+  }
 
   return true;
 }
diff --git a/chrome/browser/process_singleton_win.cc b/chrome/browser/process_singleton_win.cc
index e2312c65623a3f54ecbc18058720ccae53822e76..ec725b44296266bea1a51aea889463a0bba8449c 100644
--- a/chrome/browser/process_singleton_win.cc
+++ b/chrome/browser/process_singleton_win.cc
@@ -28,7 +28,9 @@
 #include "base/win/wmi.h"
 #include "chrome/browser/process_singleton_internal.h"
 #include "chrome/browser/shell_integration.h"
+#if 0
 #include "chrome/browser/ui/simple_message_box.h"
+#endif
 #include "chrome/browser/win/chrome_process_finder.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
@@ -163,11 +165,16 @@ bool ProcessLaunchNotification(
 }
 
 bool DisplayShouldKillMessageBox() {
+#if 0
   TRACE_EVENT0("startup", "ProcessSingleton:DisplayShouldKillMessageBox");
   return chrome::ShowQuestionMessageBoxSync(
              NULL, l10n_util::GetStringUTF16(IDS_PRODUCT_NAME),
              l10n_util::GetStringUTF16(IDS_BROWSER_HUNGBROWSER_MESSAGE)) !=
          chrome::MESSAGE_BOX_RESULT_NO;
+#endif
+  // This is called when the secondary process can't ping the primary
+  // process.
+  return false;
 }
 
 // Function was copied from Process::Terminate.
@@ -252,9 +259,13 @@ bool ProcessSingleton::EscapeVirtualization(
 }
 
 ProcessSingleton::ProcessSingleton(
+    const std::string& program_name,
     const base::FilePath& user_data_dir,
+    bool is_app_sandboxed,
     const NotificationCallback& notification_callback)
     : notification_callback_(notification_callback),
+      program_name_(program_name),
+      is_app_sandboxed_(is_app_sandboxed),
       is_virtualized_(false),
       lock_file_(INVALID_HANDLE_VALUE),
       user_data_dir_(user_data_dir),
@@ -368,13 +379,16 @@ ProcessSingleton::NotifyOtherProcessOrCreate() {
   return PROFILE_IN_USE;
 }
 
+void ProcessSingleton::StartListeningOnSocket() {}
+void ProcessSingleton::OnBrowserReady() {}
+
 // Look for a Chrome instance that uses the same profile directory. If there
 // isn't one, create a message window with its title set to the profile
 // directory path.
 bool ProcessSingleton::Create() {
   TRACE_EVENT0("startup", "ProcessSingleton::Create");
 
-  static const wchar_t kMutexName[] = L"Local\\ChromeProcessSingletonStartup!";
+  std::wstring mutexName = base::UTF8ToWide("Local\\" + program_name_ + "ProcessSingletonStartup");
 
   remote_window_ = chrome::FindRunningChromeWindow(user_data_dir_);
   if (!remote_window_ && !EscapeVirtualization(user_data_dir_)) {
@@ -383,7 +397,7 @@ bool ProcessSingleton::Create() {
     // access. As documented, it's clearer to NOT request ownership on creation
     // since it isn't guaranteed we will get it. It is better to create it
     // without ownership and explicitly get the ownership afterward.
-    base::win::ScopedHandle only_me(::CreateMutex(NULL, FALSE, kMutexName));
+    base::win::ScopedHandle only_me(::CreateMutex(NULL, FALSE, mutexName.c_str()));
     if (!only_me.IsValid()) {
       DPLOG(FATAL) << "CreateMutex failed";
       return false;
@@ -422,6 +436,17 @@ bool ProcessSingleton::Create() {
             window_.CreateNamed(base::BindRepeating(&ProcessLaunchNotification,
                                                     notification_callback_),
                                 user_data_dir_.value());
+
+        // When the app is sandboxed, firstly, the app should not be in
+        // admin mode, and even if it somehow is, messages from an unelevated
+        // instance should not be able to be sent to it.
+        if (!is_app_sandboxed_) {
+          // NB: Ensure that if the primary app gets started as elevated
+          // admin inadvertently, secondary windows running not as elevated
+          // will still be able to send messages.
+          ::ChangeWindowMessageFilterEx(window_.hwnd(), WM_COPYDATA, MSGFLT_ALLOW,
+                                        NULL);
+        }
         CHECK(result && window_.hwnd());
       }
     }
