1 //===-- interception.h ------------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of AddressSanitizer, an address sanity checker. 11 // 12 // Machinery for providing replacements/wrappers for system functions. 13 //===----------------------------------------------------------------------===// 14 15 #ifndef INTERCEPTION_H 16 #define INTERCEPTION_H 17 18 #if !defined(__linux__) && !defined(__APPLE__) && !defined(_WIN32) 19 # error "Interception doesn't work on this operating system." 20 #endif 21 22 #include "sanitizer_common/sanitizer_internal_defs.h" 23 24 // These typedefs should be used only in the interceptor definitions to replace 25 // the standard system types (e.g. SSIZE_T instead of ssize_t) 26 typedef __sanitizer::uptr SIZE_T; 27 typedef __sanitizer::sptr SSIZE_T; 28 typedef __sanitizer::sptr PTRDIFF_T; 29 typedef __sanitizer::s64 INTMAX_T; 30 typedef __sanitizer::OFF_T OFF_T; 31 typedef __sanitizer::OFF64_T OFF64_T; 32 33 // How to add an interceptor: 34 // Suppose you need to wrap/replace system function (generally, from libc): 35 // int foo(const char *bar, double baz); 36 // You'll need to: 37 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 38 // your source file. 39 // 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo". 40 // INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was 41 // intercepted successfully. 42 // You can access original function by calling REAL(foo)(bar, baz). 43 // By default, REAL(foo) will be visible only inside your interceptor, and if 44 // you want to use it in other parts of RTL, you'll need to: 45 // 3a) add DECLARE_REAL(int, foo, const char*, double) to a 46 // header file. 47 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for 48 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to: 49 // 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double) 50 // to a header file. 51 52 // Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or 53 // DECLARE_REAL(...) are located inside namespaces. 54 // 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to 55 // effectively redirect calls from "foo" to "zoo". In this case 56 // you aren't required to implement 57 // INTERCEPTOR(int, foo, const char *bar, double baz) {...} 58 // but instead you'll have to add 59 // DECLARE_REAL(int, foo, const char *bar, double baz) in your 60 // source file (to define a pointer to overriden function). 61 62 // How it works: 63 // To replace system functions on Linux we just need to declare functions 64 // with same names in our library and then obtain the real function pointers 65 // using dlsym(). 66 // There is one complication. A user may also intercept some of the functions 67 // we intercept. To resolve this we declare our interceptors with __interceptor_ 68 // prefix, and then make actual interceptors weak aliases to __interceptor_ 69 // functions. 70 // 71 // This is not so on Mac OS, where the two-level namespace makes 72 // our replacement functions invisible to other libraries. This may be overcomed 73 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared 74 // libraries in Chromium were noticed when doing so. 75 // Instead we create a dylib containing a __DATA,__interpose section that 76 // associates library functions with their wrappers. When this dylib is 77 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all 78 // the calls to interposed functions done through stubs to the wrapper 79 // functions. 80 // As it's decided at compile time which functions are to be intercepted on Mac, 81 // INTERCEPT_FUNCTION() is effectively a no-op on this system. 82 83 #if defined(__APPLE__) 84 85 // Just a pair of pointers. 86 struct interpose_substitution { 87 const uptr replacement; 88 const uptr original; 89 }; 90 91 // For a function foo() create a global pair of pointers { wrap_foo, foo } in 92 // the __DATA,__interpose section. 93 // As a result all the calls to foo() will be routed to wrap_foo() at runtime. 94 #define INTERPOSER(func_name) __attribute__((used)) \ 95 const interpose_substitution substitution_##func_name[] \ 96 __attribute__((section("__DATA, __interpose"))) = { \ 97 { reinterpret_cast<const uptr>(WRAP(func_name)), \ 98 reinterpret_cast<const uptr>(func_name) } \ 99 } 100 101 // For a function foo() and a wrapper function bar() create a global pair 102 // of pointers { bar, foo } in the __DATA,__interpose section. 103 // As a result all the calls to foo() will be routed to bar() at runtime. 104 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \ 105 const interpose_substitution substitution_##func_name[] \ 106 __attribute__((section("__DATA, __interpose"))) = { \ 107 { reinterpret_cast<const uptr>(wrapper_name), \ 108 reinterpret_cast<const uptr>(func_name) } \ 109 } 110 111 # define WRAP(x) wrap_##x 112 # define WRAPPER_NAME(x) "wrap_"#x 113 # define INTERCEPTOR_ATTRIBUTE 114 # define DECLARE_WRAPPER(ret_type, func, ...) 115 116 #elif defined(_WIN32) 117 # if defined(_DLL) // DLL CRT 118 # define WRAP(x) x 119 # define WRAPPER_NAME(x) #x 120 # define INTERCEPTOR_ATTRIBUTE 121 # else // Static CRT 122 # define WRAP(x) wrap_##x 123 # define WRAPPER_NAME(x) "wrap_"#x 124 # define INTERCEPTOR_ATTRIBUTE 125 # endif 126 # define DECLARE_WRAPPER(ret_type, func, ...) 127 #else 128 # define WRAP(x) __interceptor_ ## x 129 # define WRAPPER_NAME(x) "__interceptor_" #x 130 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 131 # define DECLARE_WRAPPER(ret_type, func, ...) \ 132 extern "C" ret_type func(__VA_ARGS__) \ 133 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 134 #endif 135 136 #if !defined(__APPLE__) 137 # define PTR_TO_REAL(x) real_##x 138 # define REAL(x) __interception::PTR_TO_REAL(x) 139 # define FUNC_TYPE(x) x##_f 140 141 # define DECLARE_REAL(ret_type, func, ...) \ 142 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 143 namespace __interception { \ 144 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 145 } 146 #else // __APPLE__ 147 # define REAL(x) x 148 # define DECLARE_REAL(ret_type, func, ...) \ 149 extern "C" ret_type func(__VA_ARGS__); 150 #endif // __APPLE__ 151 152 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 153 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 154 extern "C" ret_type WRAP(func)(__VA_ARGS__); 155 156 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 157 // macros does its job. In exceptional cases you may need to call REAL(foo) 158 // without defining INTERCEPTOR(..., foo, ...). For example, if you override 159 // foo with an interceptor for other function. 160 #if !defined(__APPLE__) 161 # define DEFINE_REAL(ret_type, func, ...) \ 162 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 163 namespace __interception { \ 164 FUNC_TYPE(func) PTR_TO_REAL(func); \ 165 } 166 #else 167 # define DEFINE_REAL(ret_type, func, ...) 168 #endif 169 170 #if !defined(__APPLE__) 171 #define INTERCEPTOR(ret_type, func, ...) \ 172 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 173 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 174 extern "C" \ 175 INTERCEPTOR_ATTRIBUTE \ 176 ret_type WRAP(func)(__VA_ARGS__) 177 #else // __APPLE__ 178 #define INTERCEPTOR(ret_type, func, ...) \ 179 extern "C" ret_type func(__VA_ARGS__); \ 180 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 181 INTERPOSER(func); \ 182 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 183 184 // Override |overridee| with |overrider|. 185 #define OVERRIDE_FUNCTION(overridee, overrider) \ 186 INTERPOSER_2(overridee, WRAP(overrider)) 187 #endif 188 189 #if defined(_WIN32) 190 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 191 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 192 namespace __interception { \ 193 FUNC_TYPE(func) PTR_TO_REAL(func); \ 194 } \ 195 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 196 extern "C" \ 197 INTERCEPTOR_ATTRIBUTE \ 198 ret_type __stdcall WRAP(func)(__VA_ARGS__) 199 #endif 200 201 // ISO C++ forbids casting between pointer-to-function and pointer-to-object, 202 // so we use casting via an integral type __interception::uptr, 203 // assuming that system is POSIX-compliant. Using other hacks seem 204 // challenging, as we don't even pass function type to 205 // INTERCEPT_FUNCTION macro, only its name. 206 namespace __interception { 207 #if defined(_WIN64) 208 typedef unsigned long long uptr; // NOLINT 209 #else 210 typedef unsigned long uptr; // NOLINT 211 #endif // _WIN64 212 } // namespace __interception 213 214 #define INCLUDED_FROM_INTERCEPTION_LIB 215 216 #if defined(__linux__) 217 # include "interception_linux.h" 218 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func) 219 #elif defined(__APPLE__) 220 # include "interception_mac.h" 221 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 222 #else // defined(_WIN32) 223 # include "interception_win.h" 224 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 225 #endif 226 227 #undef INCLUDED_FROM_INTERCEPTION_LIB 228 229 #endif // INTERCEPTION_H 230
