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 13 namespace base { 14 namespace 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. 23 class 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 void* original_function() const; 61 62 63 private: 64 HMODULE module_handle_; 65 void* intercept_function_; 66 void* original_function_; 67 IMAGE_THUNK_DATA* iat_thunk_; 68 69 DISALLOW_COPY_AND_ASSIGN(IATPatchFunction); 70 }; 71 72 BASE_EXPORT DWORD ModifyCode(void* old_code, void* new_code, int length); 73 74 } // namespace win 75 } // namespace base 76 77 #endif // BASE_WIN_IAT_PATCH_FUNCTION_H_ 78
