interception.h revision 50a002ecad3f0a10c136496e5b6289bd3c71590e
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; 30// WARNING: OFF_T may be different from OS type off_t, depending on the value of 31// _FILE_OFFSET_BITS. This definition of OFF_T matches the ABI of system calls 32// like pread and mmap, as opposed to pread64 and mmap64. 33// Mac and Linux/x86-64 are special. 34#if defined(__APPLE__) || (defined(__linux__) && defined(__x86_64__)) 35typedef __sanitizer::u64 OFF_T; 36#else 37typedef __sanitizer::uptr OFF_T; 38#endif 39typedef __sanitizer::u64 OFF64_T; 40 41// How to add an interceptor: 42// Suppose you need to wrap/replace system function (generally, from libc): 43// int foo(const char *bar, double baz); 44// You'll need to: 45// 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 46// your source file. 47// 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo". 48// INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was 49// intercepted successfully. 50// You can access original function by calling REAL(foo)(bar, baz). 51// By default, REAL(foo) will be visible only inside your interceptor, and if 52// you want to use it in other parts of RTL, you'll need to: 53// 3a) add DECLARE_REAL(int, foo, const char*, double) to a 54// header file. 55// However, if the call "INTERCEPT_FUNCTION(foo)" and definition for 56// INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to: 57// 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double) 58// to a header file. 59 60// Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or 61// DECLARE_REAL(...) are located inside namespaces. 62// 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to 63// effectively redirect calls from "foo" to "zoo". In this case 64// you aren't required to implement 65// INTERCEPTOR(int, foo, const char *bar, double baz) {...} 66// but instead you'll have to add 67// DECLARE_REAL(int, foo, const char *bar, double baz) in your 68// source file (to define a pointer to overriden function). 69 70// How it works: 71// To replace system functions on Linux we just need to declare functions 72// with same names in our library and then obtain the real function pointers 73// using dlsym(). 74// There is one complication. A user may also intercept some of the functions 75// we intercept. To resolve this we declare our interceptors with __interceptor_ 76// prefix, and then make actual interceptors weak aliases to __interceptor_ 77// functions. 78// 79// This is not so on Mac OS, where the two-level namespace makes 80// our replacement functions invisible to other libraries. This may be overcomed 81// using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared 82// libraries in Chromium were noticed when doing so. 83// Instead we create a dylib containing a __DATA,__interpose section that 84// associates library functions with their wrappers. When this dylib is 85// preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all 86// the calls to interposed functions done through stubs to the wrapper 87// functions. 88// As it's decided at compile time which functions are to be intercepted on Mac, 89// INTERCEPT_FUNCTION() is effectively a no-op on this system. 90 91#if defined(__APPLE__) 92 93// Just a pair of pointers. 94struct 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)) \ 103const 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)) \ 113const 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) wrap_##x 131# define WRAPPER_NAME(x) "wrap_"#x 132# define INTERCEPTOR_ATTRIBUTE 133# endif 134# define DECLARE_WRAPPER(ret_type, func, ...) 135#else 136# define WRAP(x) __interceptor_ ## x 137# define WRAPPER_NAME(x) "__interceptor_" #x 138# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 139# define DECLARE_WRAPPER(ret_type, func, ...) \ 140 extern "C" ret_type func(__VA_ARGS__) \ 141 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 142#endif 143 144#if !defined(__APPLE__) 145# define PTR_TO_REAL(x) real_##x 146# define REAL(x) __interception::PTR_TO_REAL(x) 147# define FUNC_TYPE(x) x##_f 148 149# define DECLARE_REAL(ret_type, func, ...) \ 150 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 151 namespace __interception { \ 152 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 153 } 154#else // __APPLE__ 155# define REAL(x) x 156# define DECLARE_REAL(ret_type, func, ...) \ 157 extern "C" ret_type func(__VA_ARGS__); 158#endif // __APPLE__ 159 160#define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 161 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 162 extern "C" ret_type WRAP(func)(__VA_ARGS__); 163 164// Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 165// macros does its job. In exceptional cases you may need to call REAL(foo) 166// without defining INTERCEPTOR(..., foo, ...). For example, if you override 167// foo with an interceptor for other function. 168#if !defined(__APPLE__) 169# define DEFINE_REAL(ret_type, func, ...) \ 170 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 171 namespace __interception { \ 172 FUNC_TYPE(func) PTR_TO_REAL(func); \ 173 } 174#else 175# define DEFINE_REAL(ret_type, func, ...) 176#endif 177 178#if !defined(__APPLE__) 179#define INTERCEPTOR(ret_type, func, ...) \ 180 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 181 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 182 extern "C" \ 183 INTERCEPTOR_ATTRIBUTE \ 184 ret_type WRAP(func)(__VA_ARGS__) 185#else // __APPLE__ 186#define INTERCEPTOR(ret_type, func, ...) \ 187 extern "C" ret_type func(__VA_ARGS__); \ 188 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 189 INTERPOSER(func); \ 190 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 191 192// Override |overridee| with |overrider|. 193#define OVERRIDE_FUNCTION(overridee, overrider) \ 194 INTERPOSER_2(overridee, WRAP(overrider)) 195#endif 196 197#if defined(_WIN32) 198# define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 199 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 200 namespace __interception { \ 201 FUNC_TYPE(func) PTR_TO_REAL(func); \ 202 } \ 203 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 204 extern "C" \ 205 INTERCEPTOR_ATTRIBUTE \ 206 ret_type __stdcall WRAP(func)(__VA_ARGS__) 207#endif 208 209// ISO C++ forbids casting between pointer-to-function and pointer-to-object, 210// so we use casting via an integral type __interception::uptr, 211// assuming that system is POSIX-compliant. Using other hacks seem 212// challenging, as we don't even pass function type to 213// INTERCEPT_FUNCTION macro, only its name. 214namespace __interception { 215#if defined(_WIN64) 216typedef unsigned long long uptr; // NOLINT 217#else 218typedef unsigned long uptr; // NOLINT 219#endif // _WIN64 220} // namespace __interception 221 222#define INCLUDED_FROM_INTERCEPTION_LIB 223 224#if defined(__linux__) 225# include "interception_linux.h" 226# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func) 227#elif defined(__APPLE__) 228# include "interception_mac.h" 229# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 230#else // defined(_WIN32) 231# include "interception_win.h" 232# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 233#endif 234 235#undef INCLUDED_FROM_INTERCEPTION_LIB 236 237#endif // INTERCEPTION_H 238