Add sandbox support for Windows process mitigations

sandbox/win/src/broker_services.cc

Index: sandbox/win/src/broker_services.cc
===================================================================
--- sandbox/win/src/broker_services.cc	(revision 155197)
+++ sandbox/win/src/broker_services.cc	(working copy)
@@ -12,6 +12,7 @@
 #include "base/win/startup_information.h"
 #include "base/win/windows_version.h"
 #include "sandbox/win/src/app_container.h"
+#include "sandbox/win/src/process_mitigations.h"
 #include "sandbox/win/src/sandbox_policy_base.h"
 #include "sandbox/win/src/sandbox.h"
 #include "sandbox/win/src/target_process.h"
@@ -320,14 +321,51 @@
         const_cast<wchar_t*>(desktop.c_str());
   }
 
+  int attribute_count = 0;
   const AppContainerAttributes* app_container = policy_base->GetAppContainer();
+  if (app_container)
+    ++attribute_count;
+
+  DWORD64 mitigations = GetProcessMitigationPolicyFlags(
+                            policy->GetProcessMitigations());
+  if (mitigations)
+    ++attribute_count;
+
+  if (!startup_info.InitializeProcThreadAttributeList(attribute_count))
+    return SBOX_ERROR_GENERIC;
+
   if (app_container) {
-    startup_info.InitializeProcThreadAttributeList(1);
     result = app_container->ShareForStartup(&startup_info);
     if (SBOX_ALL_OK != result)
       return result;
   }
 
+  if (mitigations) {
+#ifndef _WIN64
+    // A 64-bit flags attribute is illegal on 32-bit Win 7 and below.
+    if (base::win::GetVersion() < base::win::VERSION_WIN8) {
+      DWORD mitigations32 = static_cast<DWORD>(mitigations);
+      if (!startup_info.UpdateProcThreadAttribute(
+               PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY, &mitigations32,
+               sizeof(mitigations32))) {
+        return SBOX_ERROR_GENERIC;
+      }
+    } else {
+      if (!startup_info.UpdateProcThreadAttribute(
+               PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY, &mitigations,
+               sizeof(mitigations))) {
+        return SBOX_ERROR_GENERIC;
+      }
+    }
+#else
+    if (!startup_info.UpdateProcThreadAttribute(
+              PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY, &mitigations,
+              sizeof(mitigations))) {
+      return SBOX_ERROR_GENERIC;
+    }
+#endif
+  }
+
   // Construct the thread pool here in case it is expensive.
   // The thread pool is shared by all the targets
   if (NULL == thread_pool_)