Bug 1859708: Add rule to allow read access to the binary dir for GPU sandbox. r=cmartin

This also changes the way we populate the cached binary dir string, so that when
it is populated, it is done in SandboxBroker::Initialize.

Differential Revision: https://phabricator.services.mozilla.com/D205099

js/xpconnect/src/XPCShellImpl.cpp

@@ -1084,6 +1084,10 @@ int XRE_XPCShellMain(int argc, char** argv, char** envp,
   // stability, we should instantiate COM ASAP so that we can ensure that these
   // global settings are configured before anything can interfere.
   mscom::ProcessRuntime mscom;
+
+#  ifdef MOZ_SANDBOX
+  nsAutoString binDirPath;
+#  endif
 #endif
 
   // The provider needs to outlive the call to shutting down XPCOM.
@@ -1103,6 +1107,11 @@ int XRE_XPCShellMain(int argc, char** argv, char** envp,
       return 1;
     }
 
+#if defined(XP_WIN) && defined(MOZ_SANDBOX)
+    // We need the binary directory to initialize the windows sandbox.
+    MOZ_ALWAYS_SUCCEEDS(appDir->GetPath(binDirPath));
+#endif
+
     dirprovider.SetAppFile(appFile);
 
     nsCOMPtr<nsIFile> greDir;
@@ -1301,7 +1310,7 @@ int XRE_XPCShellMain(int argc, char** argv, char** envp,
 #  if defined(MOZ_SANDBOX)
     // Required for sandboxed child processes.
     if (aShellData->sandboxBrokerServices) {
-      SandboxBroker::Initialize(aShellData->sandboxBrokerServices);
+      SandboxBroker::Initialize(aShellData->sandboxBrokerServices, binDirPath);
       SandboxBroker::GeckoDependentInitialize();
     } else {
       NS_WARNING(

security/sandbox/win/src/sandboxbroker/sandboxBroker.cpp

@@ -30,7 +30,6 @@
 #include "mozilla/Telemetry.h"
 #include "mozilla/WinDllServices.h"
 #include "mozilla/WindowsVersion.h"
-#include "mozilla/WinHeaderOnlyUtils.h"
 #include "mozilla/ipc/LaunchError.h"
 #include "nsAppDirectoryServiceDefs.h"
 #include "nsCOMPtr.h"
@@ -116,11 +115,27 @@ static sandbox::ResultCode AddWin32kLockdownPolicy(
   return result;
 }
 
+static void CacheDirAndAutoClear(const nsAString& aDir,
+                                 StaticAutoPtr<nsString>* cacheVar) {
+  *cacheVar = new nsString(aDir);
+  ClearOnShutdown(cacheVar);
+
+  // Convert network share path to format for sandbox policy.
+  if (Substring(**cacheVar, 0, 2).Equals(u"\\\\"_ns)) {
+    (*cacheVar)->InsertLiteral(u"??\\UNC", 1);
+  }
+}
+
 /* static */
-void SandboxBroker::Initialize(sandbox::BrokerServices* aBrokerServices) {
+void SandboxBroker::Initialize(sandbox::BrokerServices* aBrokerServices,
+                               const nsAString& aBinDir) {
   sBrokerService = aBrokerServices;
 
   sRunningFromNetworkDrive = widget::WinUtils::RunningFromANetworkDrive();
+
+  if (!aBinDir.IsEmpty()) {
+    CacheDirAndAutoClear(aBinDir, &sBinDir);
+  }
 }
 
 static void CacheDirAndAutoClear(nsIProperties* aDirSvc, const char* aDirKey,
@@ -135,14 +150,9 @@ static void CacheDirAndAutoClear(nsIProperties* aDirSvc, const char* aDirKey,
     return;
   }
 
-  *cacheVar = new nsString();
-  ClearOnShutdown(cacheVar);
-  MOZ_ALWAYS_SUCCEEDS(dirToCache->GetPath(**cacheVar));
-
-  // Convert network share path to format for sandbox policy.
-  if (Substring(**cacheVar, 0, 2).Equals(u"\\\\"_ns)) {
-    (*cacheVar)->InsertLiteral(u"??\\UNC", 1);
-  }
+  nsAutoString dirPath;
+  MOZ_ALWAYS_SUCCEEDS(dirToCache->GetPath(dirPath));
+  CacheDirAndAutoClear(dirPath, cacheVar);
 }
 
 /* static */
@@ -166,7 +176,6 @@ void SandboxBroker::GeckoDependentInitialize() {
       return;
     }
 
-    CacheDirAndAutoClear(dirSvc, NS_GRE_DIR, &sBinDir);
     CacheDirAndAutoClear(dirSvc, NS_APP_USER_PROFILE_50_DIR, &sProfileDir);
     CacheDirAndAutoClear(dirSvc, NS_WIN_LOCAL_APPDATA_DIR, &sLocalAppDataDir);
 #ifdef ENABLE_SYSTEM_EXTENSION_DIRS
@@ -481,33 +490,11 @@ static sandbox::ResultCode AllowProxyLoadFromBinDir(
     sandbox::TargetPolicy* aPolicy) {
   // Allow modules in the directory containing the executable such as
   // mozglue.dll, nss3.dll, etc.
-  static UniquePtr<nsString> sInstallDir;
-  if (!sInstallDir) {
-    // Since this function can be called before sBinDir is initialized,
-    // we cache the install path by ourselves.
-    UniquePtr<wchar_t[]> appDirStr;
-    if (GetInstallDirectory(appDirStr)) {
-      sInstallDir = MakeUnique<nsString>(appDirStr.get());
-      sInstallDir->Append(u"\\*");
-
-      auto setClearOnShutdown = [ptr = &sInstallDir]() -> void {
-        ClearOnShutdown(ptr);
-      };
-      if (NS_IsMainThread()) {
-        setClearOnShutdown();
-      } else {
-        SchedulerGroup::Dispatch(NS_NewRunnableFunction(
-            "InitSignedPolicyRulesToBypassCig", std::move(setClearOnShutdown)));
-      }
-    }
-
-    if (!sInstallDir) {
-      return sandbox::SBOX_ERROR_GENERIC;
-    }
-  }
+  nsAutoString rulePath(*sBinDir);
+  rulePath.Append(u"\\*"_ns);
   return aPolicy->AddRule(sandbox::TargetPolicy::SUBSYS_SIGNED_BINARY,
                           sandbox::TargetPolicy::SIGNED_ALLOW_LOAD,
-                          sInstallDir->get());
+                          rulePath.get());
 }
 
 static sandbox::ResultCode AddCigToPolicy(
@@ -1084,6 +1071,10 @@ void SandboxBroker::SetSecurityLevelForGPUProcess(int32_t aSandboxLevel) {
                        sandbox::TargetPolicy::FILES_ALLOW_ANY,
                        L"\\??\\pipe\\gecko-crash-server-pipe.*"));
 
+  // Add rule to allow read access to installation directory.
+  AddCachedDirRule(mPolicy, sandbox::TargetPolicy::FILES_ALLOW_READONLY,
+                   sBinDir, u"\\*"_ns);
+
   // The GPU process needs to write to a shader cache for performance reasons
   if (sProfileDir) {
     AddCachedDirRule(mPolicy, sandbox::TargetPolicy::FILES_ALLOW_DIR_ANY,

security/sandbox/win/src/sandboxbroker/sandboxBroker.h

@@ -75,7 +75,8 @@ class SandboxBroker : public AbstractSandboxBroker {
  public:
   SandboxBroker();
 
-  static void Initialize(sandbox::BrokerServices* aBrokerServices);
+  static void Initialize(sandbox::BrokerServices* aBrokerServices,
+                         const nsAString& aBinDir);
 
   static void EnsureLpacPermsissionsOnDir(const nsString& aDir);
 

toolkit/xre/nsAppRunner.cpp

@@ -4224,7 +4224,9 @@ int XREMain::XRE_mainInit(bool* aExitFlag) {
 
 #if defined(MOZ_SANDBOX) && defined(XP_WIN)
   if (mAppData->sandboxBrokerServices) {
-    SandboxBroker::Initialize(mAppData->sandboxBrokerServices);
+    nsAutoString binDirPath;
+    MOZ_ALWAYS_SUCCEEDS(xreBinDirectory->GetPath(binDirPath));
+    SandboxBroker::Initialize(mAppData->sandboxBrokerServices, binDirPath);
   } else {
 #  if defined(MOZ_SANDBOX)
     // If we're sandboxing content and we fail to initialize, then crashing here

toolkit/xre/nsEmbedFunctions.cpp

@@ -525,7 +525,7 @@ nsresult XRE_InitChildProcess(int aArgc, char* aArgv[],
 #if defined(XP_WIN)
 #  if defined(MOZ_SANDBOX)
   if (aChildData->sandboxBrokerServices) {
-    SandboxBroker::Initialize(aChildData->sandboxBrokerServices);
+    SandboxBroker::Initialize(aChildData->sandboxBrokerServices, u""_ns);
     SandboxBroker::GeckoDependentInitialize();
   }
 #  endif  // defined(MOZ_SANDBOX)