1// Copyright (c) 2011 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef BASE_WIN_IAT_PATCH_FUNCTION_H_ 6#define BASE_WIN_IAT_PATCH_FUNCTION_H_ 7 8#include <windows.h> 9 10#include "base/base_export.h" 11#include "base/basictypes.h" 12 13namespace base { 14namespace win { 15 16// A class that encapsulates Import Address Table patching helpers and restores 17// the original function in the destructor. 18// 19// It will intercept functions for a specific DLL imported from another DLL. 20// This is the case when, for example, we want to intercept 21// CertDuplicateCertificateContext function (exported from crypt32.dll) called 22// by wininet.dll. 23class BASE_EXPORT IATPatchFunction { 24 public: 25 IATPatchFunction(); 26 ~IATPatchFunction(); 27 28 // Intercept a function in an import table of a specific 29 // module. Save the original function and the import 30 // table address. These values will be used later 31 // during Unpatch 32 // 33 // Arguments: 34 // module Module to be intercepted 35 // imported_from_module Module that exports the 'function_name' 36 // function_name Name of the API to be intercepted 37 // 38 // Returns: Windows error code (winerror.h). NO_ERROR if successful 39 // 40 // Note: Patching a function will make the IAT patch take some "ownership" on 41 // |module|. It will LoadLibrary(module) to keep the DLL alive until a call 42 // to Unpatch(), which will call FreeLibrary() and allow the module to be 43 // unloaded. The idea is to help prevent the DLL from going away while a 44 // patch is still active. 45 DWORD Patch(const wchar_t* module, 46 const char* imported_from_module, 47 const char* function_name, 48 void* new_function); 49 50 // Unpatch the IAT entry using internally saved original 51 // function. 52 // 53 // Returns: Windows error code (winerror.h). NO_ERROR if successful 54 DWORD Unpatch(); 55 56 bool is_patched() const { 57 return (NULL != intercept_function_); 58 } 59 60 private: 61 HMODULE module_handle_; 62 void* intercept_function_; 63 void* original_function_; 64 IMAGE_THUNK_DATA* iat_thunk_; 65 66 DISALLOW_COPY_AND_ASSIGN(IATPatchFunction); 67}; 68 69} // namespace win 70} // namespace base 71 72#endif // BASE_WIN_IAT_PATCH_FUNCTION_H_ 73