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(__FreeBSD__) && \ 19 !defined(__APPLE__) && !defined(_WIN32) 20 # error "Interception doesn't work on this operating system." 21 #endif 22 23 #include "sanitizer_common/sanitizer_internal_defs.h" 24 25 // These typedefs should be used only in the interceptor definitions to replace 26 // the standard system types (e.g. SSIZE_T instead of ssize_t) 27 typedef __sanitizer::uptr SIZE_T; 28 typedef __sanitizer::sptr SSIZE_T; 29 typedef __sanitizer::sptr PTRDIFF_T; 30 typedef __sanitizer::s64 INTMAX_T; 31 typedef __sanitizer::OFF_T OFF_T; 32 typedef __sanitizer::OFF64_T OFF64_T; 33 34 // How to add an interceptor: 35 // Suppose you need to wrap/replace system function (generally, from libc): 36 // int foo(const char *bar, double baz); 37 // You'll need to: 38 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 39 // your source file. See the notes below for cases when 40 // INTERCEPTOR_WITH_SUFFIX(...) should be used instead. 41 // 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo". 42 // INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was 43 // intercepted successfully. 44 // You can access original function by calling REAL(foo)(bar, baz). 45 // By default, REAL(foo) will be visible only inside your interceptor, and if 46 // you want to use it in other parts of RTL, you'll need to: 47 // 3a) add DECLARE_REAL(int, foo, const char*, double) to a 48 // header file. 49 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for 50 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to: 51 // 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double) 52 // to a header file. 53 54 // Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or 55 // DECLARE_REAL(...) are located inside namespaces. 56 // 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to 57 // effectively redirect calls from "foo" to "zoo". In this case 58 // you aren't required to implement 59 // INTERCEPTOR(int, foo, const char *bar, double baz) {...} 60 // but instead you'll have to add 61 // DECLARE_REAL(int, foo, const char *bar, double baz) in your 62 // source file (to define a pointer to overriden function). 63 // 3. Some Mac functions have symbol variants discriminated by 64 // additional suffixes, e.g. _$UNIX2003 (see 65 // https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html 66 // for more details). To intercept such functions you need to use the 67 // INTERCEPTOR_WITH_SUFFIX(...) macro. 68 69 // How it works: 70 // To replace system functions on Linux we just need to declare functions 71 // with same names in our library and then obtain the real function pointers 72 // using dlsym(). 73 // There is one complication. A user may also intercept some of the functions 74 // we intercept. To resolve this we declare our interceptors with __interceptor_ 75 // prefix, and then make actual interceptors weak aliases to __interceptor_ 76 // functions. 77 // 78 // This is not so on Mac OS, where the two-level namespace makes 79 // our replacement functions invisible to other libraries. This may be overcomed 80 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared 81 // libraries in Chromium were noticed when doing so. 82 // Instead we create a dylib containing a __DATA,__interpose section that 83 // associates library functions with their wrappers. When this dylib is 84 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all 85 // the calls to interposed functions done through stubs to the wrapper 86 // functions. 87 // As it's decided at compile time which functions are to be intercepted on Mac, 88 // INTERCEPT_FUNCTION() is effectively a no-op on this system. 89 90 #if defined(__APPLE__) 91 #include <sys/cdefs.h> // For __DARWIN_ALIAS_C(). 92 93 // Just a pair of pointers. 94 struct interpose_substitution { 95 const uptr replacement; 96 const uptr original; 97 }; 98 99 // For a function foo() create a global pair of pointers { wrap_foo, foo } in 100 // the __DATA,__interpose section. 101 // As a result all the calls to foo() will be routed to wrap_foo() at runtime. 102 #define INTERPOSER(func_name) __attribute__((used)) \ 103 const interpose_substitution substitution_##func_name[] \ 104 __attribute__((section("__DATA, __interpose"))) = { \ 105 { reinterpret_cast<const uptr>(WRAP(func_name)), \ 106 reinterpret_cast<const uptr>(func_name) } \ 107 } 108 109 // For a function foo() and a wrapper function bar() create a global pair 110 // of pointers { bar, foo } in the __DATA,__interpose section. 111 // As a result all the calls to foo() will be routed to bar() at runtime. 112 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \ 113 const interpose_substitution substitution_##func_name[] \ 114 __attribute__((section("__DATA, __interpose"))) = { \ 115 { reinterpret_cast<const uptr>(wrapper_name), \ 116 reinterpret_cast<const uptr>(func_name) } \ 117 } 118 119 # define WRAP(x) wrap_##x 120 # define WRAPPER_NAME(x) "wrap_"#x 121 # define INTERCEPTOR_ATTRIBUTE 122 # define DECLARE_WRAPPER(ret_type, func, ...) 123 124 #elif defined(_WIN32) 125 # if defined(_DLL) // DLL CRT 126 # define WRAP(x) x 127 # define WRAPPER_NAME(x) #x 128 # define INTERCEPTOR_ATTRIBUTE 129 # else // Static CRT 130 # define WRAP(x) __asan_wrap_##x 131 # define WRAPPER_NAME(x) "__asan_wrap_"#x 132 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport) 133 # endif 134 # define DECLARE_WRAPPER(ret_type, func, ...) \ 135 extern "C" ret_type func(__VA_ARGS__); 136 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \ 137 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__); 138 #elif defined(__FreeBSD__) 139 # define WRAP(x) __interceptor_ ## x 140 # define WRAPPER_NAME(x) "__interceptor_" #x 141 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 142 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher 143 // priority than weak ones so weak aliases won't work for indirect calls 144 // in position-independent (-fPIC / -fPIE) mode. 145 # define DECLARE_WRAPPER(ret_type, func, ...) \ 146 extern "C" ret_type func(__VA_ARGS__) \ 147 __attribute__((alias("__interceptor_" #func), visibility("default"))); 148 #else 149 # define WRAP(x) __interceptor_ ## x 150 # define WRAPPER_NAME(x) "__interceptor_" #x 151 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 152 # define DECLARE_WRAPPER(ret_type, func, ...) \ 153 extern "C" ret_type func(__VA_ARGS__) \ 154 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 155 #endif 156 157 #if !defined(__APPLE__) 158 # define PTR_TO_REAL(x) real_##x 159 # define REAL(x) __interception::PTR_TO_REAL(x) 160 # define FUNC_TYPE(x) x##_f 161 162 # define DECLARE_REAL(ret_type, func, ...) \ 163 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 164 namespace __interception { \ 165 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 166 } 167 #else // __APPLE__ 168 # define REAL(x) x 169 # define DECLARE_REAL(ret_type, func, ...) \ 170 extern "C" ret_type func(__VA_ARGS__); 171 #endif // __APPLE__ 172 173 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 174 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 175 extern "C" ret_type WRAP(func)(__VA_ARGS__); 176 177 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 178 // macros does its job. In exceptional cases you may need to call REAL(foo) 179 // without defining INTERCEPTOR(..., foo, ...). For example, if you override 180 // foo with an interceptor for other function. 181 #if !defined(__APPLE__) 182 # define DEFINE_REAL(ret_type, func, ...) \ 183 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 184 namespace __interception { \ 185 FUNC_TYPE(func) PTR_TO_REAL(func); \ 186 } 187 #else 188 # define DEFINE_REAL(ret_type, func, ...) 189 #endif 190 191 #if !defined(__APPLE__) 192 #define INTERCEPTOR(ret_type, func, ...) \ 193 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 194 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 195 extern "C" \ 196 INTERCEPTOR_ATTRIBUTE \ 197 ret_type WRAP(func)(__VA_ARGS__) 198 199 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now. 200 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 201 INTERCEPTOR(ret_type, func, __VA_ARGS__) 202 203 #else // __APPLE__ 204 205 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \ 206 extern "C" ret_type func(__VA_ARGS__) suffix; \ 207 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 208 INTERPOSER(func); \ 209 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 210 211 #define INTERCEPTOR(ret_type, func, ...) \ 212 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__) 213 214 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 215 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__) 216 217 // Override |overridee| with |overrider|. 218 #define OVERRIDE_FUNCTION(overridee, overrider) \ 219 INTERPOSER_2(overridee, WRAP(overrider)) 220 #endif 221 222 #if defined(_WIN32) 223 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 224 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 225 namespace __interception { \ 226 FUNC_TYPE(func) PTR_TO_REAL(func); \ 227 } \ 228 DECLARE_WRAPPER_WINAPI(ret_type, func, __VA_ARGS__) \ 229 extern "C" \ 230 INTERCEPTOR_ATTRIBUTE \ 231 ret_type __stdcall WRAP(func)(__VA_ARGS__) 232 #endif 233 234 // ISO C++ forbids casting between pointer-to-function and pointer-to-object, 235 // so we use casting via an integral type __interception::uptr, 236 // assuming that system is POSIX-compliant. Using other hacks seem 237 // challenging, as we don't even pass function type to 238 // INTERCEPT_FUNCTION macro, only its name. 239 namespace __interception { 240 #if defined(_WIN64) 241 typedef unsigned long long uptr; // NOLINT 242 #else 243 typedef unsigned long uptr; // NOLINT 244 #endif // _WIN64 245 } // namespace __interception 246 247 #define INCLUDED_FROM_INTERCEPTION_LIB 248 249 #if defined(__linux__) || defined(__FreeBSD__) 250 # include "interception_linux.h" 251 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) 252 # define INTERCEPT_FUNCTION_VER(func, symver) \ 253 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) 254 #elif defined(__APPLE__) 255 # include "interception_mac.h" 256 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 257 # define INTERCEPT_FUNCTION_VER(func, symver) \ 258 INTERCEPT_FUNCTION_VER_MAC(func, symver) 259 #else // defined(_WIN32) 260 # include "interception_win.h" 261 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 262 # define INTERCEPT_FUNCTION_VER(func, symver) \ 263 INTERCEPT_FUNCTION_VER_WIN(func, symver) 264 #endif 265 266 #undef INCLUDED_FROM_INTERCEPTION_LIB 267 268 #endif // INTERCEPTION_H 269