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 #include "sanitizer_common/sanitizer_internal_defs.h" 17 18 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \ 19 !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \ 20 !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS 21 # error "Interception doesn't work on this operating system." 22 #endif 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::u64 UINTMAX_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 SANITIZER_MAC 91 #include <sys/cdefs.h> // For __DARWIN_ALIAS_C(). 92 93 // Just a pair of pointers. 94 struct interpose_substitution { 95 const __sanitizer::uptr replacement; 96 const __sanitizer::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 SANITIZER_WINDOWS 125 # define WRAP(x) __asan_wrap_##x 126 # define WRAPPER_NAME(x) "__asan_wrap_"#x 127 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport) 128 # define DECLARE_WRAPPER(ret_type, func, ...) \ 129 extern "C" ret_type func(__VA_ARGS__); 130 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \ 131 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__); 132 #elif SANITIZER_RTEMS 133 # define WRAP(x) x 134 # define WRAPPER_NAME(x) #x 135 # define INTERCEPTOR_ATTRIBUTE 136 # define DECLARE_WRAPPER(ret_type, func, ...) 137 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD 138 # define WRAP(x) __interceptor_ ## x 139 # define WRAPPER_NAME(x) "__interceptor_" #x 140 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 141 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher 142 // priority than weak ones so weak aliases won't work for indirect calls 143 // in position-independent (-fPIC / -fPIE) mode. 144 # define DECLARE_WRAPPER(ret_type, func, ...) \ 145 extern "C" ret_type func(__VA_ARGS__) \ 146 __attribute__((alias("__interceptor_" #func), visibility("default"))); 147 #elif !SANITIZER_FUCHSIA 148 # define WRAP(x) __interceptor_ ## x 149 # define WRAPPER_NAME(x) "__interceptor_" #x 150 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 151 # define DECLARE_WRAPPER(ret_type, func, ...) \ 152 extern "C" ret_type func(__VA_ARGS__) \ 153 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 154 #endif 155 156 #if SANITIZER_FUCHSIA 157 // There is no general interception at all on Fuchsia. 158 // Sanitizer runtimes just define functions directly to preempt them, 159 // and have bespoke ways to access the underlying libc functions. 160 # include <zircon/sanitizer.h> 161 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 162 # define REAL(x) __unsanitized_##x 163 # define DECLARE_REAL(ret_type, func, ...) 164 #elif SANITIZER_RTEMS 165 # define REAL(x) __real_ ## x 166 # define DECLARE_REAL(ret_type, func, ...) \ 167 extern "C" ret_type REAL(func)(__VA_ARGS__); 168 #elif !SANITIZER_MAC 169 # define PTR_TO_REAL(x) real_##x 170 # define REAL(x) __interception::PTR_TO_REAL(x) 171 # define FUNC_TYPE(x) x##_type 172 173 # define DECLARE_REAL(ret_type, func, ...) \ 174 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 175 namespace __interception { \ 176 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 177 } 178 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src) 179 #else // SANITIZER_MAC 180 # define REAL(x) x 181 # define DECLARE_REAL(ret_type, func, ...) \ 182 extern "C" ret_type func(__VA_ARGS__); 183 # define ASSIGN_REAL(x, y) 184 #endif // SANITIZER_MAC 185 186 #if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS 187 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 188 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 189 extern "C" ret_type WRAP(func)(__VA_ARGS__); 190 #else 191 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) 192 #endif 193 194 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 195 // macros does its job. In exceptional cases you may need to call REAL(foo) 196 // without defining INTERCEPTOR(..., foo, ...). For example, if you override 197 // foo with an interceptor for other function. 198 #if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS 199 # define DEFINE_REAL(ret_type, func, ...) \ 200 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 201 namespace __interception { \ 202 FUNC_TYPE(func) PTR_TO_REAL(func); \ 203 } 204 #else 205 # define DEFINE_REAL(ret_type, func, ...) 206 #endif 207 208 #if SANITIZER_FUCHSIA 209 210 // We need to define the __interceptor_func name just to get 211 // sanitizer_common/scripts/gen_dynamic_list.py to export func. 212 // But we don't need to export __interceptor_func to get that. 213 #define INTERCEPTOR(ret_type, func, ...) \ 214 extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \ 215 __interceptor_##func(__VA_ARGS__); \ 216 extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__) 217 218 #elif !SANITIZER_MAC 219 220 #define INTERCEPTOR(ret_type, func, ...) \ 221 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 222 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 223 extern "C" \ 224 INTERCEPTOR_ATTRIBUTE \ 225 ret_type WRAP(func)(__VA_ARGS__) 226 227 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now. 228 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 229 INTERCEPTOR(ret_type, func, __VA_ARGS__) 230 231 #else // SANITIZER_MAC 232 233 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \ 234 extern "C" ret_type func(__VA_ARGS__) suffix; \ 235 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 236 INTERPOSER(func); \ 237 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 238 239 #define INTERCEPTOR(ret_type, func, ...) \ 240 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__) 241 242 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 243 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__) 244 245 // Override |overridee| with |overrider|. 246 #define OVERRIDE_FUNCTION(overridee, overrider) \ 247 INTERPOSER_2(overridee, WRAP(overrider)) 248 #endif 249 250 #if SANITIZER_WINDOWS 251 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 252 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 253 namespace __interception { \ 254 FUNC_TYPE(func) PTR_TO_REAL(func); \ 255 } \ 256 extern "C" \ 257 INTERCEPTOR_ATTRIBUTE \ 258 ret_type __stdcall WRAP(func)(__VA_ARGS__) 259 #endif 260 261 // ISO C++ forbids casting between pointer-to-function and pointer-to-object, 262 // so we use casting via an integral type __interception::uptr, 263 // assuming that system is POSIX-compliant. Using other hacks seem 264 // challenging, as we don't even pass function type to 265 // INTERCEPT_FUNCTION macro, only its name. 266 namespace __interception { 267 #if defined(_WIN64) 268 typedef unsigned long long uptr; // NOLINT 269 #else 270 typedef unsigned long uptr; // NOLINT 271 #endif // _WIN64 272 } // namespace __interception 273 274 #define INCLUDED_FROM_INTERCEPTION_LIB 275 276 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \ 277 SANITIZER_OPENBSD || SANITIZER_SOLARIS 278 279 # include "interception_linux.h" 280 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) 281 # define INTERCEPT_FUNCTION_VER(func, symver) \ 282 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) 283 #elif SANITIZER_MAC 284 # include "interception_mac.h" 285 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 286 # define INTERCEPT_FUNCTION_VER(func, symver) \ 287 INTERCEPT_FUNCTION_VER_MAC(func, symver) 288 #elif SANITIZER_WINDOWS 289 # include "interception_win.h" 290 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 291 # define INTERCEPT_FUNCTION_VER(func, symver) \ 292 INTERCEPT_FUNCTION_VER_WIN(func, symver) 293 #endif 294 295 #undef INCLUDED_FROM_INTERCEPTION_LIB 296 297 #endif // INTERCEPTION_H 298