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