interception.h revision 9213e07a7f95b3e634b97a7bba70849badcf2c8a
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. 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. 93struct 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)) \ 102const 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)) \ 112const 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 extern "C" ret_type func(__VA_ARGS__); 135# define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \ 136 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__); 137#else 138# define WRAP(x) __interceptor_ ## x 139# define WRAPPER_NAME(x) "__interceptor_" #x 140# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 141# define DECLARE_WRAPPER(ret_type, func, ...) \ 142 extern "C" ret_type func(__VA_ARGS__) \ 143 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 144#endif 145 146#if !defined(__APPLE__) 147# define PTR_TO_REAL(x) real_##x 148# define REAL(x) __interception::PTR_TO_REAL(x) 149# define FUNC_TYPE(x) x##_f 150 151# define DECLARE_REAL(ret_type, func, ...) \ 152 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 153 namespace __interception { \ 154 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 155 } 156#else // __APPLE__ 157# define REAL(x) x 158# define DECLARE_REAL(ret_type, func, ...) \ 159 extern "C" ret_type func(__VA_ARGS__); 160#endif // __APPLE__ 161 162#define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 163 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 164 extern "C" ret_type WRAP(func)(__VA_ARGS__); 165 166// Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 167// macros does its job. In exceptional cases you may need to call REAL(foo) 168// without defining INTERCEPTOR(..., foo, ...). For example, if you override 169// foo with an interceptor for other function. 170#if !defined(__APPLE__) 171# define DEFINE_REAL(ret_type, func, ...) \ 172 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 173 namespace __interception { \ 174 FUNC_TYPE(func) PTR_TO_REAL(func); \ 175 } 176#else 177# define DEFINE_REAL(ret_type, func, ...) 178#endif 179 180#if !defined(__APPLE__) 181#define INTERCEPTOR(ret_type, func, ...) \ 182 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 183 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 184 extern "C" \ 185 INTERCEPTOR_ATTRIBUTE \ 186 ret_type WRAP(func)(__VA_ARGS__) 187 188// We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now. 189#define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 190 INTERCEPTOR(ret_type, func, __VA_ARGS__) 191 192#else // __APPLE__ 193 194#define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \ 195 extern "C" ret_type func(__VA_ARGS__) suffix; \ 196 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 197 INTERPOSER(func); \ 198 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 199 200#define INTERCEPTOR(ret_type, func, ...) \ 201 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__) 202 203#define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 204 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__) 205 206// Override |overridee| with |overrider|. 207#define OVERRIDE_FUNCTION(overridee, overrider) \ 208 INTERPOSER_2(overridee, WRAP(overrider)) 209#endif 210 211#if defined(_WIN32) 212# define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 213 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 214 namespace __interception { \ 215 FUNC_TYPE(func) PTR_TO_REAL(func); \ 216 } \ 217 DECLARE_WRAPPER_WINAPI(ret_type, func, __VA_ARGS__) \ 218 extern "C" \ 219 INTERCEPTOR_ATTRIBUTE \ 220 ret_type __stdcall WRAP(func)(__VA_ARGS__) 221#endif 222 223// ISO C++ forbids casting between pointer-to-function and pointer-to-object, 224// so we use casting via an integral type __interception::uptr, 225// assuming that system is POSIX-compliant. Using other hacks seem 226// challenging, as we don't even pass function type to 227// INTERCEPT_FUNCTION macro, only its name. 228namespace __interception { 229#if defined(_WIN64) 230typedef unsigned long long uptr; // NOLINT 231#else 232typedef unsigned long uptr; // NOLINT 233#endif // _WIN64 234} // namespace __interception 235 236#define INCLUDED_FROM_INTERCEPTION_LIB 237 238#if defined(__linux__) 239# include "interception_linux.h" 240# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX(func) 241#elif defined(__APPLE__) 242# include "interception_mac.h" 243# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 244#else // defined(_WIN32) 245# include "interception_win.h" 246# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 247#endif 248 249#undef INCLUDED_FROM_INTERCEPTION_LIB 250 251#endif // INTERCEPTION_H 252