1 //===-- interception.h ------------------------------------------*- C++ -*-===// 2 // 3 // This file is distributed under the University of Illinois Open Source 4 // License. See LICENSE.TXT for details. 5 // 6 //===----------------------------------------------------------------------===// 7 // 8 // This file is a part of AddressSanitizer, an address sanity checker. 9 // 10 // Machinery for providing replacements/wrappers for system functions. 11 //===----------------------------------------------------------------------===// 12 13 #ifndef INTERCEPTION_H 14 #define INTERCEPTION_H 15 16 #if !defined(__linux__) && !defined(__FreeBSD__) && !defined(__APPLE__) && \ 17 !defined(__NetBSD__) && !defined(_WIN32) && !defined(__Fuchsia__) 18 # error "Interception doesn't work on this operating system." 19 #endif 20 21 #include "sanitizer_common/sanitizer_internal_defs.h" 22 23 // These typedefs should be used only in the interceptor definitions to replace 24 // the standard system types (e.g. SSIZE_T instead of ssize_t) 25 typedef __sanitizer::uptr SIZE_T; 26 typedef __sanitizer::sptr SSIZE_T; 27 typedef __sanitizer::sptr PTRDIFF_T; 28 typedef __sanitizer::s64 INTMAX_T; 29 typedef __sanitizer::OFF_T OFF_T; 30 typedef __sanitizer::OFF64_T OFF64_T; 31 32 // How to add an interceptor: 33 // Suppose you need to wrap/replace system function (generally, from libc): 34 // int foo(const char *bar, double baz); 35 // You'll need to: 36 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 37 // your source file. See the notes below for cases when 38 // INTERCEPTOR_WITH_SUFFIX(...) should be used instead. 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 // 3. Some Mac functions have symbol variants discriminated by 62 // additional suffixes, e.g. _$UNIX2003 (see 63 // https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html 64 // for more details). To intercept such functions you need to use the 65 // INTERCEPTOR_WITH_SUFFIX(...) macro. 66 67 // How it works: 68 // To replace system functions on Linux we just need to declare functions 69 // with same names in our library and then obtain the real function pointers 70 // using dlsym(). 71 // There is one complication. A user may also intercept some of the functions 72 // we intercept. To resolve this we declare our interceptors with __interceptor_ 73 // prefix, and then make actual interceptors weak aliases to __interceptor_ 74 // functions. 75 // 76 // This is not so on Mac OS, where the two-level namespace makes 77 // our replacement functions invisible to other libraries. This may be overcomed 78 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared 79 // libraries in Chromium were noticed when doing so. 80 // Instead we create a dylib containing a __DATA,__interpose section that 81 // associates library functions with their wrappers. When this dylib is 82 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all 83 // the calls to interposed functions done through stubs to the wrapper 84 // functions. 85 // As it's decided at compile time which functions are to be intercepted on Mac, 86 // INTERCEPT_FUNCTION() is effectively a no-op on this system. 87 88 #if defined(__APPLE__) 89 #include <sys/cdefs.h> // For __DARWIN_ALIAS_C(). 90 91 // Just a pair of pointers. 92 struct interpose_substitution { 93 const __sanitizer::uptr replacement; 94 const __sanitizer::uptr original; 95 }; 96 97 // For a function foo() create a global pair of pointers { wrap_foo, foo } in 98 // the __DATA,__interpose section. 99 // As a result all the calls to foo() will be routed to wrap_foo() at runtime. 100 #define INTERPOSER(func_name) __attribute__((used)) \ 101 const interpose_substitution substitution_##func_name[] \ 102 __attribute__((section("__DATA, __interpose"))) = { \ 103 { reinterpret_cast<const uptr>(WRAP(func_name)), \ 104 reinterpret_cast<const uptr>(func_name) } \ 105 } 106 107 // For a function foo() and a wrapper function bar() create a global pair 108 // of pointers { bar, foo } in the __DATA,__interpose section. 109 // As a result all the calls to foo() will be routed to bar() at runtime. 110 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \ 111 const interpose_substitution substitution_##func_name[] \ 112 __attribute__((section("__DATA, __interpose"))) = { \ 113 { reinterpret_cast<const uptr>(wrapper_name), \ 114 reinterpret_cast<const uptr>(func_name) } \ 115 } 116 117 # define WRAP(x) wrap_##x 118 # define WRAPPER_NAME(x) "wrap_"#x 119 # define INTERCEPTOR_ATTRIBUTE 120 # define DECLARE_WRAPPER(ret_type, func, ...) 121 122 #elif defined(_WIN32) 123 # define WRAP(x) __asan_wrap_##x 124 # define WRAPPER_NAME(x) "__asan_wrap_"#x 125 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport) 126 # define DECLARE_WRAPPER(ret_type, func, ...) \ 127 extern "C" ret_type func(__VA_ARGS__); 128 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \ 129 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__); 130 #elif defined(__FreeBSD__) || defined(__NetBSD__) 131 # define WRAP(x) __interceptor_ ## x 132 # define WRAPPER_NAME(x) "__interceptor_" #x 133 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 134 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher 135 // priority than weak ones so weak aliases won't work for indirect calls 136 // in position-independent (-fPIC / -fPIE) mode. 137 # define DECLARE_WRAPPER(ret_type, func, ...) \ 138 extern "C" ret_type func(__VA_ARGS__) \ 139 __attribute__((alias("__interceptor_" #func), visibility("default"))); 140 #elif !defined(__Fuchsia__) 141 # define WRAP(x) __interceptor_ ## x 142 # define WRAPPER_NAME(x) "__interceptor_" #x 143 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 144 # define DECLARE_WRAPPER(ret_type, func, ...) \ 145 extern "C" ret_type func(__VA_ARGS__) \ 146 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 147 #endif 148 149 #if defined(__Fuchsia__) 150 // There is no general interception at all on Fuchsia. 151 // Sanitizer runtimes just define functions directly to preempt them, 152 // and have bespoke ways to access the underlying libc functions. 153 # include <zircon/sanitizer.h> 154 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 155 # define REAL(x) __unsanitized_##x 156 # define DECLARE_REAL(ret_type, func, ...) 157 #elif !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 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src) 168 #else // __APPLE__ 169 # define REAL(x) x 170 # define DECLARE_REAL(ret_type, func, ...) \ 171 extern "C" ret_type func(__VA_ARGS__); 172 # define ASSIGN_REAL(x, y) 173 #endif // __APPLE__ 174 175 #if !defined(__Fuchsia__) 176 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 177 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 178 extern "C" ret_type WRAP(func)(__VA_ARGS__); 179 #else 180 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) 181 #endif 182 183 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 184 // macros does its job. In exceptional cases you may need to call REAL(foo) 185 // without defining INTERCEPTOR(..., foo, ...). For example, if you override 186 // foo with an interceptor for other function. 187 #if !defined(__APPLE__) && !defined(__Fuchsia__) 188 # define DEFINE_REAL(ret_type, func, ...) \ 189 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 190 namespace __interception { \ 191 FUNC_TYPE(func) PTR_TO_REAL(func); \ 192 } 193 #else 194 # define DEFINE_REAL(ret_type, func, ...) 195 #endif 196 197 #if defined(__Fuchsia__) 198 199 // We need to define the __interceptor_func name just to get 200 // sanitizer_common/scripts/gen_dynamic_list.py to export func. 201 // But we don't need to export __interceptor_func to get that. 202 #define INTERCEPTOR(ret_type, func, ...) \ 203 extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \ 204 __interceptor_##func(__VA_ARGS__); \ 205 extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__) 206 207 #elif !defined(__APPLE__) 208 209 #define INTERCEPTOR(ret_type, func, ...) \ 210 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 211 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 212 extern "C" \ 213 INTERCEPTOR_ATTRIBUTE \ 214 ret_type WRAP(func)(__VA_ARGS__) 215 216 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now. 217 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 218 INTERCEPTOR(ret_type, func, __VA_ARGS__) 219 220 #else // __APPLE__ 221 222 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \ 223 extern "C" ret_type func(__VA_ARGS__) suffix; \ 224 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 225 INTERPOSER(func); \ 226 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 227 228 #define INTERCEPTOR(ret_type, func, ...) \ 229 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__) 230 231 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 232 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__) 233 234 // Override |overridee| with |overrider|. 235 #define OVERRIDE_FUNCTION(overridee, overrider) \ 236 INTERPOSER_2(overridee, WRAP(overrider)) 237 #endif 238 239 #if defined(_WIN32) 240 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 241 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 242 namespace __interception { \ 243 FUNC_TYPE(func) PTR_TO_REAL(func); \ 244 } \ 245 extern "C" \ 246 INTERCEPTOR_ATTRIBUTE \ 247 ret_type __stdcall WRAP(func)(__VA_ARGS__) 248 #endif 249 250 // ISO C++ forbids casting between pointer-to-function and pointer-to-object, 251 // so we use casting via an integral type __interception::uptr, 252 // assuming that system is POSIX-compliant. Using other hacks seem 253 // challenging, as we don't even pass function type to 254 // INTERCEPT_FUNCTION macro, only its name. 255 namespace __interception { 256 #if defined(_WIN64) 257 typedef unsigned long long uptr; // NOLINT 258 #else 259 typedef unsigned long uptr; // NOLINT 260 #endif // _WIN64 261 } // namespace __interception 262 263 #define INCLUDED_FROM_INTERCEPTION_LIB 264 265 #if defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__) 266 # include "interception_linux.h" 267 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) 268 # define INTERCEPT_FUNCTION_VER(func, symver) \ 269 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) 270 #elif defined(__APPLE__) 271 # include "interception_mac.h" 272 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 273 # define INTERCEPT_FUNCTION_VER(func, symver) \ 274 INTERCEPT_FUNCTION_VER_MAC(func, symver) 275 #elif defined(_WIN32) 276 # include "interception_win.h" 277 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 278 # define INTERCEPT_FUNCTION_VER(func, symver) \ 279 INTERCEPT_FUNCTION_VER_WIN(func, symver) 280 #endif 281 282 #undef INCLUDED_FROM_INTERCEPTION_LIB 283 284 #endif // INTERCEPTION_H 285