Ignore DEP and SEHOP flags on Win64

sandbox/win/src/process_mitigations.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sandbox/win/src/process_mitigations.h"
 
 #include "base/win/windows_version.h"
 #include "sandbox/win/src/nt_internals.h"
 #include "sandbox/win/src/sandbox_utils.h"
 #include "sandbox/win/src/win_utils.h"
@@ skipping 173 matching lines @@
   else
     *size = sizeof(*policy_flags);
 #else
 #error This platform is not supported.
 #endif
 
   // Nothing for Win XP or Vista.
   if (version <= base::win::VERSION_VISTA)
     return;
 
+  // DEP and SEHOP are not valid for 64-bit Windows
+#if !defined(_WIN64)

[cpu_(ooo_6.6-7.5), 2013/02/11 19:05:09]

I don't like the silent ignore. in sandbox_policy_base we return
SBOX_ERROR_BAD_PARAMS in PolicyBase::SetProcessMitigations so we should do that
here.

[jschuh, 2013/02/11 21:26:49]

But it's ignored because the OS is already enforcing the behavior. And I didn't
want the mitigation interface to force the caller to enumerate through the
complicated tree of what OS versions support what mitigations. I designed it to
just encapsulate the logic and do the right thing, failing only when the OS
doesn't support something that it should.

   if (flags & MITIGATION_DEP) {
     *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ENABLE;
     if (!(flags & MITIGATION_DEP_NO_ATL_THUNK))
       *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ATL_THUNK_ENABLE;
   }
 
   if (flags & MITIGATION_SEHOP)
     *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_SEHOP_ENABLE;
+#endif
 
   // Win 7
   if (version < base::win::VERSION_WIN8)
     return;
 
   if (flags & MITIGATION_RELOCATE_IMAGE) {
     *policy_flags |=
         PROCESS_CREATION_MITIGATION_POLICY_FORCE_RELOCATE_IMAGES_ALWAYS_ON;
     if (flags & MITIGATION_RELOCATE_IMAGE_REQUIRED) {
       *policy_flags |=
@@ skipping 108 matching lines @@
 
 bool CanSetProcessMitigationsPreStartup(MitigationFlags flags) {
   // These mitigations cannot be enabled prior to startup.
   return !(flags & (MITIGATION_STRICT_HANDLE_CHECKS |
                     MITIGATION_WIN32K_DISABLE |
                     MITIGATION_DLL_SEARCH_ORDER));
 }
 
 }  // namespace sandbox