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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// This file declares a helpers to intercept functions from a DLL.
//
// This set of functions are designed to intercept functions for a
// specific DLL imported from another DLL. This is the case when,
// for example, we want to intercept CertDuplicateCertificateContext
// function (exported from crypt32.dll) called by wininet.dll.
#ifndef BASE_IAT_PATCH_H__
#define BASE_IAT_PATCH_H__
#include <windows.h>
#include "base/basictypes.h"
#include "base/pe_image.h"
namespace iat_patch {
// Helper to intercept a function in an import table of a specific
// module.
//
// Arguments:
// module_handle Module to be intercepted
// imported_from_module Module that exports the symbol
// function_name Name of the API to be intercepted
// new_function Interceptor function
// old_function Receives the original function pointer
// iat_thunk Receives pointer to IAT_THUNK_DATA
// for the API from the import table.
//
// Returns: Returns NO_ERROR on success or Windows error code
// as defined in winerror.h
//
DWORD InterceptImportedFunction(HMODULE module_handle,
const char* imported_from_module,
const char* function_name,
void* new_function,
void** old_function,
IMAGE_THUNK_DATA** iat_thunk);
// Restore intercepted IAT entry with the original function.
//
// Arguments:
// intercept_function Interceptor function
// original_function Receives the original function pointer
//
// Returns: Returns NO_ERROR on success or Windows error code
// as defined in winerror.h
//
DWORD RestoreImportedFunction(void* intercept_function,
void* original_function,
IMAGE_THUNK_DATA* iat_thunk);
// Change the page protection (of code pages) to writable and copy
// the data at the specified location
//
// Arguments:
// old_code Target location to copy
// new_code Source
// length Number of bytes to copy
//
// Returns: Windows error code (winerror.h). NO_ERROR if successful
//
DWORD ModifyCode(void* old_code,
void* new_code,
int length);
// A class that encapsulates IAT patching helpers and restores
// the original function in the destructor.
class IATPatchFunction {
public:
IATPatchFunction();
~IATPatchFunction();
// Intercept a function in an import table of a specific
// module. Save the original function and the import
// table address. These values will be used later
// during Unpatch
//
// Arguments:
// module_handle Module to be intercepted
// imported_from_module Module that exports the 'function_name'
// function_name Name of the API to be intercepted
//
// Returns: Windows error code (winerror.h). NO_ERROR if successful
//
DWORD Patch(HMODULE module_handle,
const char* imported_from_module,
const char* function_name,
void* new_function);
// Unpatch the IAT entry using internally saved original
// function.
//
// Returns: Windows error code (winerror.h). NO_ERROR if successful
//
DWORD Unpatch();
bool is_patched() const {
return (NULL != intercept_function_);
}
private:
void* intercept_function_;
void* original_function_;
IMAGE_THUNK_DATA* iat_thunk_;
DISALLOW_EVIL_CONSTRUCTORS(IATPatchFunction);
};
} // namespace iat_patch
#endif // BASE_IAT_PATCH_H__
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