interception.h revision 6fb47af2d2d305adbfc3d41bea589d1527a364a9
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) 26typedef __sanitizer::uptr SIZE_T; 27typedef __sanitizer::sptr SSIZE_T; 28typedef __sanitizer::sptr PTRDIFF_T; 29typedef __sanitizer::s64 INTMAX_T; 30typedef __sanitizer::OFF_T OFF_T; 31typedef __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. 86struct 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)) \ 95const 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)) \ 105const 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. 206namespace __interception { 207#if defined(_WIN64) 208typedef unsigned long long uptr; // NOLINT 209#else 210typedef 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