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// Copyright 2013 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 "chrome_elf/ntdll_cache.h"
#include <stdint.h>
#include <windows.h>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/win/pe_image.h"
#include "chrome_elf/thunk_getter.h"
#include "sandbox/win/src/interception_internal.h"
#include "sandbox/win/src/internal_types.h"
#include "sandbox/win/src/service_resolver.h"
FunctionLookupTable g_ntdll_lookup;
// Allocate storage for thunks in a page of this module to save on doing
// an extra allocation at run time.
#pragma section(".crthunk",read,execute)
__declspec(allocate(".crthunk")) sandbox::ThunkData g_nt_thunk_storage;
namespace {
bool EnumExportsCallback(const base::win::PEImage& image,
DWORD ordinal,
DWORD hint,
LPCSTR name,
PVOID function_addr,
LPCSTR forward,
PVOID cookie) {
// Our lookup only cares about named functions that are in ntdll, so skip
// unnamed or forwarded exports.
if (name && function_addr)
g_ntdll_lookup[std::string(name)] = function_addr;
return true;
}
} // namespace
void InitCache() {
HMODULE ntdll_handle = ::GetModuleHandle(L"ntdll.dll");
base::win::PEImage ntdll_image(ntdll_handle);
ntdll_image.EnumExports(EnumExportsCallback, NULL);
// If ntdll has already been patched, don't copy it.
const bool kRelaxed = false;
// Create a thunk via the appropriate ServiceResolver instance.
scoped_ptr<sandbox::ServiceResolverThunk> thunk(GetThunk(kRelaxed));
if (thunk.get()) {
BYTE* thunk_storage = reinterpret_cast<BYTE*>(&g_nt_thunk_storage);
// Mark the thunk storage as readable and writeable, since we
// are ready to write to it.
DWORD old_protect = 0;
if (!::VirtualProtect(&g_nt_thunk_storage,
sizeof(g_nt_thunk_storage),
PAGE_EXECUTE_READWRITE,
&old_protect)) {
return;
}
size_t storage_used = 0;
NTSTATUS ret = thunk->CopyThunk(::GetModuleHandle(sandbox::kNtdllName),
"NtCreateFile",
thunk_storage,
sizeof(sandbox::ThunkData),
&storage_used);
if (!NT_SUCCESS(ret)) {
memset(&g_nt_thunk_storage, 0, sizeof(g_nt_thunk_storage));
}
// Ensure that the pointer to the old function can't be changed.
::VirtualProtect(&g_nt_thunk_storage,
sizeof(g_nt_thunk_storage),
PAGE_EXECUTE_READ,
&old_protect);
}
}
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