Sandbox: Some cleanup after the previous changes.

No real code change.

BUG=27218
TEST=current tests.

Review URL: http://codereview.chromium.org/597050

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@38837 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 461 insertions, 553 deletions

diff --git a/sandbox/src/resolver.cc b/sandbox/src/resolver.cc
index c2a8136..7ed02e4 100644
--- a/sandbox/src/resolver.cc
+++ b/sandbox/src/resolver.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2010 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.
 
@@ -7,54 +7,6 @@
 #include "base/pe_image.h"
 #include "sandbox/src/sandbox_nt_util.h"
 
-namespace {
-
-#pragma pack(push, 1)
-struct InternalThunk {
-  // This struct contains roughly the following code:
-  // sub esp, 8                             // Create working space
-  // push edx                               // Save register
-  // mov edx, [esp + 0xc]                   // Get return adddress
-  // mov [esp + 8], edx                     // Store return address
-  // mov dword ptr [esp + 0xc], 0x7c401200  // Store extra argument
-  // mov dword ptr [esp + 4], 0x40010203    // Store address to jump to
-  // pop edx                                // Restore register
-  // ret                                    // Jump to interceptor
-  //
-  // This code only modifies esp and eip so it must work with to normal calling
-  // convention. It is assembled as:
-  //
-  // 00 83ec08           sub     esp,8
-  // 03 52               push    edx
-  // 04 8b54240c         mov     edx,dword ptr [esp + 0Ch]
-  // 08 89542408         mov     dword ptr [esp + 8], edx
-  // 0c c744240c0012407c mov     dword ptr [esp + 0Ch], 7C401200h
-  // 14 c744240403020140 mov     dword ptr [esp + 4], 40010203h
-  // 1c 5a               pop     edx
-  // 1d c3               ret
-  InternalThunk() {
-    opcodes_1 = 0x5208ec83;
-    opcodes_2 = 0x0c24548b;
-    opcodes_3 = 0x08245489;
-    opcodes_4 = 0x0c2444c7;
-    opcodes_5 = 0x042444c7;
-    opcodes_6 = 0xc35a;
-    extra_argument = 0;
-    interceptor_function = 0;
-  };
-  ULONG opcodes_1;         // = 0x5208ec83
-  ULONG opcodes_2;         // = 0x0c24548b
-  ULONG opcodes_3;         // = 0x08245489
-  ULONG opcodes_4;         // = 0x0c2444c7
-  ULONG extra_argument;
-  ULONG opcodes_5;         // = 0x042444c7
-  ULONG interceptor_function;
-  USHORT opcodes_6;         // = 0xc35a
-};
-#pragma pack(pop)
-
-};  // namespace
-
 namespace sandbox {
 
 NTSTATUS ResolverThunk::Init(const void* target_module,
@@ -88,28 +40,6 @@ NTSTATUS ResolverThunk::Init(const void* target_module,
   return ret;
 }
 
-size_t ResolverThunk::GetInternalThunkSize() const {
-  return sizeof(InternalThunk);
-}
-
-bool ResolverThunk::SetInternalThunk(void* storage, size_t storage_bytes,
-                                     const void* original_function,
-                                     const void* interceptor) {
-  if (storage_bytes < sizeof(InternalThunk))
-    return false;
-
-  InternalThunk* thunk = new(storage, NT_PLACE) InternalThunk;
-
-#pragma warning(push)
-#pragma warning(disable: 4311)
-  // These casts generate warnings because they are 32 bit specific.
-  thunk->interceptor_function = reinterpret_cast<ULONG>(interceptor);
-  thunk->extra_argument = reinterpret_cast<ULONG>(original_function);
-#pragma warning(pop)
-
-  return true;
-}
-
 NTSTATUS ResolverThunk::ResolveInterceptor(const void* interceptor_module,
                                            const char* interceptor_name,
                                            const void** address) {
@@ -129,11 +59,4 @@ NTSTATUS ResolverThunk::ResolveInterceptor(const void* interceptor_module,
   return STATUS_SUCCESS;
 }
 
-NTSTATUS ResolverThunk::ResolveTarget(const void* module,
-                                      const char* function_name,
-                                      void** address) {
-  const void** casted = const_cast<const void**>(address);
-  return ResolverThunk::ResolveInterceptor(module, function_name, casted);
-}
-
 }  // namespace sandbox
diff --git a/sandbox/src/resolver_32.cc b/sandbox/src/resolver_32.cc
new file mode 100644
index 0000000..ae5c168
--- /dev/null
+++ b/sandbox/src/resolver_32.cc
@@ -0,0 +1,88 @@
+// Copyright (c) 2006-2010 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/src/resolver.h"
+
+#include "sandbox/src/sandbox_nt_util.h"
+
+namespace {
+
+#pragma pack(push, 1)
+struct InternalThunk {
+  // This struct contains roughly the following code:
+  // sub esp, 8                             // Create working space
+  // push edx                               // Save register
+  // mov edx, [esp + 0xc]                   // Get return adddress
+  // mov [esp + 8], edx                     // Store return address
+  // mov dword ptr [esp + 0xc], 0x7c401200  // Store extra argument
+  // mov dword ptr [esp + 4], 0x40010203    // Store address to jump to
+  // pop edx                                // Restore register
+  // ret                                    // Jump to interceptor
+  //
+  // This code only modifies esp and eip so it must work with to normal calling
+  // convention. It is assembled as:
+  //
+  // 00 83ec08           sub     esp,8
+  // 03 52               push    edx
+  // 04 8b54240c         mov     edx,dword ptr [esp + 0Ch]
+  // 08 89542408         mov     dword ptr [esp + 8], edx
+  // 0c c744240c0012407c mov     dword ptr [esp + 0Ch], 7C401200h
+  // 14 c744240403020140 mov     dword ptr [esp + 4], 40010203h
+  // 1c 5a               pop     edx
+  // 1d c3               ret
+  InternalThunk() {
+    opcodes_1 = 0x5208ec83;
+    opcodes_2 = 0x0c24548b;
+    opcodes_3 = 0x08245489;
+    opcodes_4 = 0x0c2444c7;
+    opcodes_5 = 0x042444c7;
+    opcodes_6 = 0xc35a;
+    extra_argument = 0;
+    interceptor_function = 0;
+  };
+  ULONG opcodes_1;         // = 0x5208ec83
+  ULONG opcodes_2;         // = 0x0c24548b
+  ULONG opcodes_3;         // = 0x08245489
+  ULONG opcodes_4;         // = 0x0c2444c7
+  ULONG extra_argument;
+  ULONG opcodes_5;         // = 0x042444c7
+  ULONG interceptor_function;
+  USHORT opcodes_6;         // = 0xc35a
+};
+#pragma pack(pop)
+
+};  // namespace
+
+namespace sandbox {
+
+bool ResolverThunk::SetInternalThunk(void* storage, size_t storage_bytes,
+                                     const void* original_function,
+                                     const void* interceptor) {
+  if (storage_bytes < sizeof(InternalThunk))
+    return false;
+
+  InternalThunk* thunk = new(storage, NT_PLACE) InternalThunk;
+
+#pragma warning(push)
+#pragma warning(disable: 4311)
+  // These casts generate warnings because they are 32 bit specific.
+  thunk->interceptor_function = reinterpret_cast<ULONG>(interceptor);
+  thunk->extra_argument = reinterpret_cast<ULONG>(original_function);
+#pragma warning(pop)
+
+  return true;
+}
+
+size_t ResolverThunk::GetInternalThunkSize() const {
+  return sizeof(InternalThunk);
+}
+
+NTSTATUS ResolverThunk::ResolveTarget(const void* module,
+                                      const char* function_name,
+                                      void** address) {
+  const void** casted = const_cast<const void**>(address);
+  return ResolverThunk::ResolveInterceptor(module, function_name, casted);
+}
+
+}  // namespace sandbox
diff --git a/sandbox/src/resolver_64.cc b/sandbox/src/resolver_64.cc
index 4c736c2..96d039b 100644
--- a/sandbox/src/resolver_64.cc
+++ b/sandbox/src/resolver_64.cc
@@ -4,7 +4,6 @@
 
 #include "sandbox/src/resolver.h"
 
-#include "base/pe_image.h"
 #include "sandbox/src/sandbox_nt_util.h"
 
 namespace {
@@ -44,37 +43,6 @@ struct InternalThunk {
 
 namespace sandbox {
 
-NTSTATUS ResolverThunk::Init(const void* target_module,
-                             const void* interceptor_module,
-                             const char* target_name,
-                             const char* interceptor_name,
-                             const void* interceptor_entry_point,
-                             void* thunk_storage,
-                             size_t storage_bytes) {
-  if (NULL == thunk_storage || 0 == storage_bytes ||
-      NULL == target_module || NULL == target_name)
-    return STATUS_INVALID_PARAMETER;
-
-  if (storage_bytes < GetThunkSize())
-    return STATUS_BUFFER_TOO_SMALL;
-
-  NTSTATUS ret = STATUS_SUCCESS;
-  if (NULL == interceptor_entry_point) {
-    ret = ResolveInterceptor(interceptor_module, interceptor_name,
-                             &interceptor_entry_point);
-    if (!NT_SUCCESS(ret))
-      return ret;
-  }
-
-  ret = ResolveTarget(target_module, target_name, &target_);
-  if (!NT_SUCCESS(ret))
-    return ret;
-
-  interceptor_ = interceptor_entry_point;
-
-  return ret;
-}
-
 size_t ResolverThunk::GetInternalThunkSize() const {
   return sizeof(InternalThunk);
 }
@@ -91,25 +59,6 @@ bool ResolverThunk::SetInternalThunk(void* storage, size_t storage_bytes,
   return true;
 }
 
-NTSTATUS ResolverThunk::ResolveInterceptor(const void* interceptor_module,
-                                           const char* interceptor_name,
-                                           const void** address) {
-  DCHECK_NT(address);
-  if (!interceptor_module)
-    return STATUS_INVALID_PARAMETER;
-
-  PEImage pe(interceptor_module);
-  if (!pe.VerifyMagic())
-    return STATUS_INVALID_IMAGE_FORMAT;
-
-  *address = pe.GetProcAddress(interceptor_name);
-
-  if (!(*address))
-    return STATUS_PROCEDURE_NOT_FOUND;
-
-  return STATUS_SUCCESS;
-}
-
 NTSTATUS ResolverThunk::ResolveTarget(const void* module,
                                       const char* function_name,
                                       void** address) {
diff --git a/sandbox/src/service_resolver.cc b/sandbox/src/service_resolver.cc
index 069b37f..728555e 100644
--- a/sandbox/src/service_resolver.cc
+++ b/sandbox/src/service_resolver.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2010 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.
 
@@ -6,163 +6,9 @@
 
 #include "base/logging.h"
 #include "base/pe_image.h"
-#include "base/scoped_ptr.h"
-#include "sandbox/src/sandbox_types.h"
-#include "sandbox/src/sandbox_utils.h"
-
-
-namespace {
-#pragma pack(push, 1)
-
-const BYTE kMovEax = 0xB8;
-const BYTE kMovEdx = 0xBA;
-const USHORT kCallPtrEdx = 0x12FF;
-const USHORT kCallEdx = 0xD2FF;
-const BYTE kRet = 0xC2;
-const BYTE kNop = 0x90;
-const USHORT kJmpEdx = 0xE2FF;
-const USHORT kXorEcx = 0xC933;
-const ULONG kLeaEdx = 0x0424548D;
-const ULONG kCallFs1 = 0xC015FF64;
-const USHORT kCallFs2 = 0;
-const BYTE kCallFs3 = 0;
-const BYTE kAddEsp1 = 0x83;
-const USHORT kAddEsp2 = 0x4C4;
-const BYTE kJmp32 = 0xE9;
-
-const int kMaxService = 1000;
-
-// Service code for 32 bit systems.
-// NOTE: on win2003 "call dword ptr [edx]" is "call edx".
-struct ServiceEntry {
-  // this struct contains roughly the following code:
-  // 00 mov     eax,25h
-  // 05 mov     edx,offset SharedUserData!SystemCallStub (7ffe0300)
-  // 0a call    dword ptr [edx]
-  // 0c ret     2Ch
-  // 0f nop
-  BYTE mov_eax;         // = B8
-  ULONG service_id;
-  BYTE mov_edx;         // = BA
-  ULONG stub;
-  USHORT call_ptr_edx;  // = FF 12
-  BYTE ret;             // = C2
-  USHORT num_params;
-  BYTE nop;
-  ULONG pad1;           // Extend the structure to be the same size as the
-  ULONG pad2;           // 64 version (Wow64Entry)
-};
-
-// Service code for a 32 bit process running on a 64 bit os.
-struct Wow64Entry {
-  // This struct may contain one of two versions of code:
-  // 1. For XP, Vista and 2K3:
-  // 00 b852000000      mov     eax, 25h
-  // 05 33c9            xor     ecx, ecx
-  // 07 8d542404        lea     edx, [esp + 4]
-  // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
-  // 12 c22c00          ret     2Ch
-  //
-  // 2. For Windows 7:
-  // 00 b852000000      mov     eax, 25h
-  // 05 33c9            xor     ecx, ecx
-  // 07 8d542404        lea     edx, [esp + 4]
-  // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
-  // 12 83c404          add     esp, 4
-  // 15 c22c00          ret     2Ch
-  //
-  // So we base the structure on the bigger one:
-  BYTE mov_eax;         // = B8
-  ULONG service_id;
-  USHORT xor_ecx;       // = 33 C9
-  ULONG lea_edx;        // = 8D 54 24 04
-  ULONG call_fs1;       // = 64 FF 15 C0
-  USHORT call_fs2;      // = 00 00
-  BYTE call_fs3;        // = 00
-  BYTE add_esp1;        // = 83             or ret
-  USHORT add_esp2;      // = C4 04          or num_params
-  BYTE ret;             // = C2
-  USHORT num_params;
-};
-
-// Make sure that relaxed patching works as expected.
-COMPILE_ASSERT(sizeof(ServiceEntry) == sizeof(Wow64Entry), wrong_service_len);
-
-struct ServiceFullThunk {
-  union {
-    ServiceEntry original;
-    Wow64Entry wow_64;
-  };
-  int internal_thunk;  // Dummy member to the beginning of the internal thunk.
-};
-
-#pragma pack(pop)
-
-// Simple utility function to write to a buffer on the child, if the memery has
-// write protection attributes.
-// Arguments:
-// child_process (in): process to write to.
-// address (out): memory position on the child to write to.
-// buffer (in): local buffer with the data to write .
-// length (in): number of bytes to write.
-// Returns true on success.
-bool WriteProtectedChildMemory(HANDLE child_process,
-                               void* address,
-                               const void* buffer,
-                               size_t length) {
-  // first, remove the protections
-  DWORD old_protection;
-  if (!::VirtualProtectEx(child_process, address, length,
-                          PAGE_WRITECOPY, &old_protection))
-    return false;
-
-  SIZE_T written;
-  bool ok = ::WriteProcessMemory(child_process, address, buffer, length,
-                                 &written) && (length == written);
-
-  // always attempt to restore the original protection
-  if (!::VirtualProtectEx(child_process, address, length,
-                          old_protection, &old_protection))
-    return false;
-
-  return ok;
-}
-
-};  // namespace
 
 namespace sandbox {
 
-NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
-                                     const void* interceptor_module,
-                                     const char* target_name,
-                                     const char* interceptor_name,
-                                     const void* interceptor_entry_point,
-                                     void* thunk_storage,
-                                     size_t storage_bytes,
-                                     size_t* storage_used) {
-  NTSTATUS ret = Init(target_module, interceptor_module, target_name,
-                      interceptor_name, interceptor_entry_point,
-                      thunk_storage, storage_bytes);
-  if (!NT_SUCCESS(ret))
-    return ret;
-
-  size_t thunk_bytes = GetThunkSize();
-  scoped_array<char> thunk_buffer(new char[thunk_bytes]);
-  ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(
-                                thunk_buffer.get());
-
-  if (!IsFunctionAService(&thunk->original) &&
-      (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage)))
-    return STATUS_UNSUCCESSFUL;
-
-  ret = PerformPatch(thunk, thunk_storage);
-
-  if (NULL != storage_used)
-    *storage_used = thunk_bytes;
-
-  return ret;
-}
-
 NTSTATUS ServiceResolverThunk::ResolveInterceptor(
     const void* interceptor_module,
     const char* interceptor_name,
@@ -174,7 +20,7 @@ NTSTATUS ServiceResolverThunk::ResolveInterceptor(
 }
 
 // In this case all the work is done from the parent, so resolve is
-// just a simple GetProcAddress
+// just a simple GetProcAddress.
 NTSTATUS ServiceResolverThunk::ResolveTarget(const void* module,
                                              const char* function_name,
                                              void** address) {
@@ -185,217 +31,12 @@ NTSTATUS ServiceResolverThunk::ResolveTarget(const void* module,
   PEImage module_image(module);
   *address = module_image.GetProcAddress(function_name);
 
-  if (NULL == *address)
+  if (NULL == *address) {
+    NOTREACHED();
     return STATUS_UNSUCCESSFUL;
-
-  return STATUS_SUCCESS;
-}
-
-size_t ServiceResolverThunk::GetThunkSize() const {
-  return offsetof(ServiceFullThunk, internal_thunk) + GetInternalThunkSize();
-}
-
-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;
-
-  if (kMovEax != function_code.mov_eax ||
-      kMovEdx != function_code.mov_edx ||
-      (kCallPtrEdx != function_code.call_ptr_edx &&
-       kCallEdx != function_code.call_ptr_edx) ||
-      kRet != function_code.ret)
-    return false;
-
-  // Find the system call pointer if we don't already have it.
-  if (kCallEdx != function_code.call_ptr_edx) {
-    DWORD ki_system_call;
-    if (!::ReadProcessMemory(process_,
-                             bit_cast<const void*>(function_code.stub),
-                             &ki_system_call, sizeof(ki_system_call), &read))
-      return false;
-
-    if (sizeof(ki_system_call) != read)
-      return false;
-
-    HMODULE module_1, module_2;
-    // last check, call_stub should point to a KiXXSystemCall function on ntdll
-    if (!GetModuleHandleHelper(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
-                                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
-                               bit_cast<const wchar_t*>(ki_system_call),
-                               &module_1))
-      return false;
-
-    if (NULL != ntdll_base_) {
-      // This path is only taken when running the unit tests. We want to be
-      // able to patch a buffer in memory, so target_ is not inside ntdll.
-      module_2 = ntdll_base_;
-    } else {
-      if (!GetModuleHandleHelper(
-              GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
-                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
-              reinterpret_cast<const wchar_t*>(target_),
-              &module_2)) {
-        return false;
-      }
-    }
-
-    if (module_1 != module_2)
-      return false;
-  }
-
-  // Save the verified code
-  memcpy(local_thunk, &function_code, sizeof(function_code));
-
-  return true;
-}
-
-NTSTATUS ServiceResolverThunk::PerformPatch(void* local_thunk,
-                                            void* remote_thunk) {
-  ServiceEntry intercepted_code;
-  size_t bytes_to_write = sizeof(intercepted_code);
-  ServiceFullThunk *full_local_thunk = reinterpret_cast<ServiceFullThunk*>(
-      local_thunk);
-  ServiceFullThunk *full_remote_thunk = reinterpret_cast<ServiceFullThunk*>(
-      remote_thunk);
-
-  // patch the original code
-  memcpy(&intercepted_code, &full_local_thunk->original,
-         sizeof(intercepted_code));
-  intercepted_code.mov_eax = kMovEax;
-  intercepted_code.service_id = full_local_thunk->original.service_id;
-  intercepted_code.mov_edx = kMovEdx;
-  intercepted_code.stub = bit_cast<ULONG>(&full_remote_thunk->internal_thunk);
-  intercepted_code.call_ptr_edx = kJmpEdx;
-  if (!win2k_) {
-    intercepted_code.ret = kRet;
-    intercepted_code.num_params = full_local_thunk->original.num_params;
-    intercepted_code.nop = kNop;
-  } else {
-    bytes_to_write = offsetof(ServiceEntry, ret);
-  }
-
-  if (relative_jump_) {
-    intercepted_code.mov_eax = kJmp32;
-    intercepted_code.service_id = relative_jump_;
-    bytes_to_write = offsetof(ServiceEntry, mov_edx);
-  }
-
-  // setup the thunk
-  SetInternalThunk(&full_local_thunk->internal_thunk, GetInternalThunkSize(),
-                   remote_thunk, interceptor_);
-
-  size_t thunk_size = GetThunkSize();
-
-  // copy the local thunk buffer to the child
-  SIZE_T written;
-  if (!::WriteProcessMemory(process_, remote_thunk, local_thunk,
-                            thunk_size, &written))
-    return STATUS_UNSUCCESSFUL;
-
-  if (thunk_size != written)
-    return STATUS_UNSUCCESSFUL;
-
-  // and now change the function to intercept, on the child
-  if (NULL != ntdll_base_) {
-    // running a unit test
-    if (!::WriteProcessMemory(process_, target_, &intercepted_code,
-                              bytes_to_write, &written))
-      return STATUS_UNSUCCESSFUL;
-  } else {
-    if (!::WriteProtectedChildMemory(process_, target_, &intercepted_code,
-                                     bytes_to_write))
-      return STATUS_UNSUCCESSFUL;
   }
 
   return STATUS_SUCCESS;
 }
 
-bool ServiceResolverThunk::SaveOriginalFunction(void* local_thunk,
-                                                void* remote_thunk) {
-  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;
-
-  if (kJmp32 == function_code.mov_eax) {
-    // Plain old entry point patch. The relative jump address follows it.
-    ULONG relative = function_code.service_id;
-
-    // First, fix our copy of their patch.
-    relative += bit_cast<ULONG>(target_) - bit_cast<ULONG>(remote_thunk);
-
-    function_code.service_id = relative;
-
-    // And now, remember how to re-patch it.
-    ServiceFullThunk *full_thunk =
-        reinterpret_cast<ServiceFullThunk*>(remote_thunk);
-
-    const ULONG kJmp32Size = 5;
-
-    relative_jump_ = bit_cast<ULONG>(&full_thunk->internal_thunk) -
-                     bit_cast<ULONG>(target_) - kJmp32Size;
-  }
-
-  // Save the verified code
-  memcpy(local_thunk, &function_code, sizeof(function_code));
-
-  return true;
-}
-
-bool Wow64ResolverThunk::IsFunctionAService(void* local_thunk) const {
-  Wow64Entry function_code;
-  SIZE_T read;
-  if (!::ReadProcessMemory(process_, target_, &function_code,
-                           sizeof(function_code), &read))
-    return false;
-
-  if (sizeof(function_code) != read)
-    return false;
-
-  if (kMovEax != function_code.mov_eax || kXorEcx != function_code.xor_ecx ||
-      kLeaEdx != function_code.lea_edx || kCallFs1 != function_code.call_fs1 ||
-      kCallFs2 != function_code.call_fs2 || kCallFs3 != function_code.call_fs3)
-    return false;
-
-  if ((kAddEsp1 == function_code.add_esp1 &&
-       kAddEsp2 == function_code.add_esp2 &&
-       kRet == function_code.ret) || kRet == function_code.add_esp1) {
-    // Save the verified code
-    memcpy(local_thunk, &function_code, sizeof(function_code));
-    return true;
-  }
-
-  return false;
-}
-
-bool Win2kResolverThunk::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;
-
-  if (kMovEax != function_code.mov_eax ||
-      function_code.service_id > kMaxService)
-    return false;
-
-  // Save the verified code
-  memcpy(local_thunk, &function_code, sizeof(function_code));
-
-  return true;
-}
-
 }  // namespace sandbox
diff --git a/sandbox/src/service_resolver_32.cc b/sandbox/src/service_resolver_32.cc
new file mode 100644
index 0000000..aaa2c49
--- /dev/null
+++ b/sandbox/src/service_resolver_32.cc
@@ -0,0 +1,341 @@
+// Copyright (c) 2006-2010 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/src/service_resolver.h"
+
+#include "base/logging.h"
+#include "base/scoped_ptr.h"
+#include "sandbox/src/sandbox_utils.h"
+#include "sandbox/src/win_utils.h"
+
+namespace {
+#pragma pack(push, 1)
+
+const BYTE kMovEax = 0xB8;
+const BYTE kMovEdx = 0xBA;
+const USHORT kCallPtrEdx = 0x12FF;
+const USHORT kCallEdx = 0xD2FF;
+const BYTE kRet = 0xC2;
+const BYTE kNop = 0x90;
+const USHORT kJmpEdx = 0xE2FF;
+const USHORT kXorEcx = 0xC933;
+const ULONG kLeaEdx = 0x0424548D;
+const ULONG kCallFs1 = 0xC015FF64;
+const USHORT kCallFs2 = 0;
+const BYTE kCallFs3 = 0;
+const BYTE kAddEsp1 = 0x83;
+const USHORT kAddEsp2 = 0x4C4;
+const BYTE kJmp32 = 0xE9;
+
+const int kMaxService = 1000;
+
+// Service code for 32 bit systems.
+// NOTE: on win2003 "call dword ptr [edx]" is "call edx".
+struct ServiceEntry {
+  // this struct contains roughly the following code:
+  // 00 mov     eax,25h
+  // 05 mov     edx,offset SharedUserData!SystemCallStub (7ffe0300)
+  // 0a call    dword ptr [edx]
+  // 0c ret     2Ch
+  // 0f nop
+  BYTE mov_eax;         // = B8
+  ULONG service_id;
+  BYTE mov_edx;         // = BA
+  ULONG stub;
+  USHORT call_ptr_edx;  // = FF 12
+  BYTE ret;             // = C2
+  USHORT num_params;
+  BYTE nop;
+  ULONG pad1;           // Extend the structure to be the same size as the
+  ULONG pad2;           // 64 version (Wow64Entry)
+};
+
+// Service code for a 32 bit process running on a 64 bit os.
+struct Wow64Entry {
+  // This struct may contain one of two versions of code:
+  // 1. For XP, Vista and 2K3:
+  // 00 b852000000      mov     eax, 25h
+  // 05 33c9            xor     ecx, ecx
+  // 07 8d542404        lea     edx, [esp + 4]
+  // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
+  // 12 c22c00          ret     2Ch
+  //
+  // 2. For Windows 7:
+  // 00 b852000000      mov     eax, 25h
+  // 05 33c9            xor     ecx, ecx
+  // 07 8d542404        lea     edx, [esp + 4]
+  // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
+  // 12 83c404          add     esp, 4
+  // 15 c22c00          ret     2Ch
+  //
+  // So we base the structure on the bigger one:
+  BYTE mov_eax;         // = B8
+  ULONG service_id;
+  USHORT xor_ecx;       // = 33 C9
+  ULONG lea_edx;        // = 8D 54 24 04
+  ULONG call_fs1;       // = 64 FF 15 C0
+  USHORT call_fs2;      // = 00 00
+  BYTE call_fs3;        // = 00
+  BYTE add_esp1;        // = 83             or ret
+  USHORT add_esp2;      // = C4 04          or num_params
+  BYTE ret;             // = C2
+  USHORT num_params;
+};
+
+// Make sure that relaxed patching works as expected.
+COMPILE_ASSERT(sizeof(ServiceEntry) == sizeof(Wow64Entry), wrong_service_len);
+
+struct ServiceFullThunk {
+  union {
+    ServiceEntry original;
+    Wow64Entry wow_64;
+  };
+  int internal_thunk;  // Dummy member to the beginning of the internal thunk.
+};
+
+#pragma pack(pop)
+
+};  // namespace
+
+namespace sandbox {
+
+NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
+                                     const void* interceptor_module,
+                                     const char* target_name,
+                                     const char* interceptor_name,
+                                     const void* interceptor_entry_point,
+                                     void* thunk_storage,
+                                     size_t storage_bytes,
+                                     size_t* storage_used) {
+  NTSTATUS ret = Init(target_module, interceptor_module, target_name,
+                      interceptor_name, interceptor_entry_point,
+                      thunk_storage, storage_bytes);
+  if (!NT_SUCCESS(ret))
+    return ret;
+
+  size_t thunk_bytes = GetThunkSize();
+  scoped_array<char> thunk_buffer(new char[thunk_bytes]);
+  ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(
+                                thunk_buffer.get());
+
+  if (!IsFunctionAService(&thunk->original) &&
+      (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage)))
+    return STATUS_UNSUCCESSFUL;
+
+  ret = PerformPatch(thunk, thunk_storage);
+
+  if (NULL != storage_used)
+    *storage_used = thunk_bytes;
+
+  return ret;
+}
+
+size_t ServiceResolverThunk::GetThunkSize() const {
+  return offsetof(ServiceFullThunk, internal_thunk) + GetInternalThunkSize();
+}
+
+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;
+
+  if (kMovEax != function_code.mov_eax ||
+      kMovEdx != function_code.mov_edx ||
+      (kCallPtrEdx != function_code.call_ptr_edx &&
+       kCallEdx != function_code.call_ptr_edx) ||
+      kRet != function_code.ret)
+    return false;
+
+  // Find the system call pointer if we don't already have it.
+  if (kCallEdx != function_code.call_ptr_edx) {
+    DWORD ki_system_call;
+    if (!::ReadProcessMemory(process_,
+                             bit_cast<const void*>(function_code.stub),
+                             &ki_system_call, sizeof(ki_system_call), &read))
+      return false;
+
+    if (sizeof(ki_system_call) != read)
+      return false;
+
+    HMODULE module_1, module_2;
+    // last check, call_stub should point to a KiXXSystemCall function on ntdll
+    if (!GetModuleHandleHelper(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
+                                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
+                               bit_cast<const wchar_t*>(ki_system_call),
+                               &module_1))
+      return false;
+
+    if (NULL != ntdll_base_) {
+      // This path is only taken when running the unit tests. We want to be
+      // able to patch a buffer in memory, so target_ is not inside ntdll.
+      module_2 = ntdll_base_;
+    } else {
+      if (!GetModuleHandleHelper(
+              GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
+                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
+              reinterpret_cast<const wchar_t*>(target_),
+              &module_2)) {
+        return false;
+      }
+    }
+
+    if (module_1 != module_2)
+      return false;
+  }
+
+  // Save the verified code
+  memcpy(local_thunk, &function_code, sizeof(function_code));
+
+  return true;
+}
+
+NTSTATUS ServiceResolverThunk::PerformPatch(void* local_thunk,
+                                            void* remote_thunk) {
+  ServiceEntry intercepted_code;
+  size_t bytes_to_write = sizeof(intercepted_code);
+  ServiceFullThunk *full_local_thunk = reinterpret_cast<ServiceFullThunk*>(
+      local_thunk);
+  ServiceFullThunk *full_remote_thunk = reinterpret_cast<ServiceFullThunk*>(
+      remote_thunk);
+
+  // patch the original code
+  memcpy(&intercepted_code, &full_local_thunk->original,
+         sizeof(intercepted_code));
+  intercepted_code.mov_eax = kMovEax;
+  intercepted_code.service_id = full_local_thunk->original.service_id;
+  intercepted_code.mov_edx = kMovEdx;
+  intercepted_code.stub = bit_cast<ULONG>(&full_remote_thunk->internal_thunk);
+  intercepted_code.call_ptr_edx = kJmpEdx;
+  if (!win2k_) {
+    intercepted_code.ret = kRet;
+    intercepted_code.num_params = full_local_thunk->original.num_params;
+    intercepted_code.nop = kNop;
+  } else {
+    bytes_to_write = offsetof(ServiceEntry, ret);
+  }
+
+  if (relative_jump_) {
+    intercepted_code.mov_eax = kJmp32;
+    intercepted_code.service_id = relative_jump_;
+    bytes_to_write = offsetof(ServiceEntry, mov_edx);
+  }
+
+  // setup the thunk
+  SetInternalThunk(&full_local_thunk->internal_thunk, GetInternalThunkSize(),
+                   remote_thunk, interceptor_);
+
+  size_t thunk_size = GetThunkSize();
+
+  // copy the local thunk buffer to the child
+  SIZE_T written;
+  if (!::WriteProcessMemory(process_, remote_thunk, local_thunk,
+                            thunk_size, &written))
+    return STATUS_UNSUCCESSFUL;
+
+  if (thunk_size != written)
+    return STATUS_UNSUCCESSFUL;
+
+  // and now change the function to intercept, on the child
+  if (NULL != ntdll_base_) {
+    // running a unit test
+    if (!::WriteProcessMemory(process_, target_, &intercepted_code,
+                              bytes_to_write, &written))
+      return STATUS_UNSUCCESSFUL;
+  } else {
+    if (!WriteProtectedChildMemory(process_, target_, &intercepted_code,
+                                   bytes_to_write))
+      return STATUS_UNSUCCESSFUL;
+  }
+
+  return STATUS_SUCCESS;
+}
+
+bool ServiceResolverThunk::SaveOriginalFunction(void* local_thunk,
+                                                void* remote_thunk) {
+  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;
+
+  if (kJmp32 == function_code.mov_eax) {
+    // Plain old entry point patch. The relative jump address follows it.
+    ULONG relative = function_code.service_id;
+
+    // First, fix our copy of their patch.
+    relative += bit_cast<ULONG>(target_) - bit_cast<ULONG>(remote_thunk);
+
+    function_code.service_id = relative;
+
+    // And now, remember how to re-patch it.
+    ServiceFullThunk *full_thunk =
+        reinterpret_cast<ServiceFullThunk*>(remote_thunk);
+
+    const ULONG kJmp32Size = 5;
+
+    relative_jump_ = bit_cast<ULONG>(&full_thunk->internal_thunk) -
+                     bit_cast<ULONG>(target_) - kJmp32Size;
+  }
+
+  // Save the verified code
+  memcpy(local_thunk, &function_code, sizeof(function_code));
+
+  return true;
+}
+
+bool Wow64ResolverThunk::IsFunctionAService(void* local_thunk) const {
+  Wow64Entry function_code;
+  SIZE_T read;
+  if (!::ReadProcessMemory(process_, target_, &function_code,
+                           sizeof(function_code), &read))
+    return false;
+
+  if (sizeof(function_code) != read)
+    return false;
+
+  if (kMovEax != function_code.mov_eax || kXorEcx != function_code.xor_ecx ||
+      kLeaEdx != function_code.lea_edx || kCallFs1 != function_code.call_fs1 ||
+      kCallFs2 != function_code.call_fs2 || kCallFs3 != function_code.call_fs3)
+    return false;
+
+  if ((kAddEsp1 == function_code.add_esp1 &&
+       kAddEsp2 == function_code.add_esp2 &&
+       kRet == function_code.ret) || kRet == function_code.add_esp1) {
+    // Save the verified code
+    memcpy(local_thunk, &function_code, sizeof(function_code));
+    return true;
+  }
+
+  return false;
+}
+
+bool Win2kResolverThunk::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;
+
+  if (kMovEax != function_code.mov_eax ||
+      function_code.service_id > kMaxService)
+    return false;
+
+  // Save the verified code
+  memcpy(local_thunk, &function_code, sizeof(function_code));
+
+  return true;
+}
+
+}  // namespace sandbox
diff --git a/sandbox/src/service_resolver_64.cc b/sandbox/src/service_resolver_64.cc
index c6e5b41..7194ee4 100644
--- a/sandbox/src/service_resolver_64.cc
+++ b/sandbox/src/service_resolver_64.cc
@@ -5,8 +5,8 @@
 #include "sandbox/src/service_resolver.h"
 
 #include "base/logging.h"
-#include "base/pe_image.h"
 #include "base/scoped_ptr.h"
+#include "sandbox/src/win_utils.h"
 
 namespace {
 #pragma pack(push, 1)
@@ -41,36 +41,6 @@ struct ServiceFullThunk {
 
 #pragma pack(pop)
 
-// Simple utility function to write to a buffer on the child, if the memery has
-// write protection attributes.
-// Arguments:
-// child_process (in): process to write to.
-// address (out): memory position on the child to write to.
-// buffer (in): local buffer with the data to write .
-// length (in): number of bytes to write.
-// Returns true on success.
-bool WriteProtectedChildMemory(HANDLE child_process,
-                               void* address,
-                               const void* buffer,
-                               size_t length) {
-  // first, remove the protections
-  DWORD old_protection;
-  if (!::VirtualProtectEx(child_process, address, length,
-                          PAGE_WRITECOPY, &old_protection))
-    return false;
-
-  SIZE_T written;
-  bool ok = ::WriteProcessMemory(child_process, address, buffer, length,
-                                 &written) && (length == written);
-
-  // always attempt to restore the original protection
-  if (!::VirtualProtectEx(child_process, address, length,
-                          old_protection, &old_protection))
-    return false;
-
-  return ok;
-}
-
 };  // namespace
 
 namespace sandbox {
@@ -105,36 +75,6 @@ NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
   return ret;
 }
 
-NTSTATUS ServiceResolverThunk::ResolveInterceptor(
-    const void* interceptor_module,
-    const char* interceptor_name,
-    const void** address) {
-  // After all, we are using a locally mapped version of the exe, so the
-  // action is the same as for a target function.
-  return ResolveTarget(interceptor_module, interceptor_name,
-                       const_cast<void**>(address));
-}
-
-// In this case all the work is done from the parent, so resolve is
-// just a simple GetProcAddress.
-NTSTATUS ServiceResolverThunk::ResolveTarget(const void* module,
-                                             const char* function_name,
-                                             void** address) {
-  DCHECK(address);
-  if (NULL == module)
-    return STATUS_UNSUCCESSFUL;
-
-  PEImage module_image(module);
-  *address = module_image.GetProcAddress(function_name);
-
-  if (NULL == *address) {
-    NOTREACHED();
-    return STATUS_UNSUCCESSFUL;
-  }
-
-  return STATUS_SUCCESS;
-}
-
 size_t ServiceResolverThunk::GetThunkSize() const {
   return sizeof(ServiceFullThunk);
 }
diff --git a/sandbox/src/win_utils.cc b/sandbox/src/win_utils.cc
index bf4936b..8be9ce4 100644
--- a/sandbox/src/win_utils.cc
+++ b/sandbox/src/win_utils.cc
@@ -265,6 +265,26 @@ bool GetPathFromHandle(HANDLE handle, std::wstring* path) {
   return true;
 }
 
+bool WriteProtectedChildMemory(HANDLE child_process, void* address,
+                               const void* buffer, size_t length) {
+  // First, remove the protections.
+  DWORD old_protection;
+  if (!::VirtualProtectEx(child_process, address, length,
+                          PAGE_WRITECOPY, &old_protection))
+    return false;
+
+  SIZE_T written;
+  bool ok = ::WriteProcessMemory(child_process, address, buffer, length,
+                                 &written) && (length == written);
+
+  // Always attempt to restore the original protection.
+  if (!::VirtualProtectEx(child_process, address, length,
+                          old_protection, &old_protection))
+    return false;
+
+  return ok;
+}
+
 };  // namespace sandbox
 
 // TODO(cpu): This is not the final code we want here but we are yet
diff --git a/sandbox/src/win_utils.h b/sandbox/src/win_utils.h
index c52f3e3..8bc44b7 100644
--- a/sandbox/src/win_utils.h
+++ b/sandbox/src/win_utils.h
@@ -88,6 +88,12 @@ HKEY GetReservedKeyFromName(const std::wstring& name);
 // cannot be resolved.
 bool ResolveRegistryName(std::wstring name, std::wstring* resolved_name);
 
+// Writes |length| bytes from the provided |buffer| into the address space of
+// |child_process|, at the specified |address|, preserving the original write
+// protection attributes. Returns true on success.
+bool WriteProtectedChildMemory(HANDLE child_process, void* address,
+                               const void* buffer, size_t length);
+
 }  // namespace sandbox
 
 // Resolves a function name in NTDLL to a function pointer. The second parameter