Make chrome_elf use thunks instead of function pointers.

sandbox/win/src/service_resolver_32.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/service_resolver.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "sandbox/win/src/win_utils.h"
 
 namespace {
@@ skipping 161 matching lines @@
   if (NULL != storage_used)
     *storage_used = thunk_bytes;
 
   return ret;
 }
 
 size_t ServiceResolverThunk::GetThunkSize() const {
   return offsetof(ServiceFullThunk, internal_thunk) + GetInternalThunkSize();
 }
 
+NTSTATUS ServiceResolverThunk::CopyThunk(const void* target_module,
+                                         const char* target_name,
+                                         BYTE* thunk_storage,
+                                         size_t storage_bytes,
+                                         size_t* storage_used) {
+  NTSTATUS ret = ResolveTarget(target_module, target_name, &target_);
+  if (!NT_SUCCESS(ret))
+    return ret;
+
+  size_t thunk_bytes = GetThunkSize();

[rvargas (doing something else), 2014/03/03 22:36:46]

Did you mean to compare this against storage_bytes? Shouldn't we update
storage_used?

[Cait (Slow), 2014/03/04 15:43:56]

Done.

+  ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(thunk_storage);
+
+  if (!IsFunctionAService(&thunk->original) &&
+      (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage))) {
+    return STATUS_UNSUCCESSFUL;
+  }
+
+  return ret;
+}
+
 bool ServiceResolverThunk::IsFunctionAService(void* local_thunk) const {
   ServiceEntry function_code;
   SIZE_T read;
   if (!::ReadProcessMemory(process_, target_, &function_code,
                            sizeof(function_code), &read))
     return false;
 
   if (sizeof(function_code) != read)
     return false;
 
@@ skipping 219 matching lines @@
     return false;
   }
 
   // Save the verified code
   memcpy(local_thunk, &function_code, sizeof(function_code));
 
   return true;
 }
 
 }  // namespace sandbox