interception.h revision 360784
1//===-- interception.h ------------------------------------------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8// 9// This file is a part of AddressSanitizer, an address sanity checker. 10// 11// Machinery for providing replacements/wrappers for system functions. 12//===----------------------------------------------------------------------===// 13 14#ifndef INTERCEPTION_H 15#define INTERCEPTION_H 16 17#include "sanitizer_common/sanitizer_internal_defs.h" 18 19#if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \ 20 !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \ 21 !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS 22# error "Interception doesn't work on this operating system." 23#endif 24 25// These typedefs should be used only in the interceptor definitions to replace 26// the standard system types (e.g. SSIZE_T instead of ssize_t) 27typedef __sanitizer::uptr SIZE_T; 28typedef __sanitizer::sptr SSIZE_T; 29typedef __sanitizer::sptr PTRDIFF_T; 30typedef __sanitizer::s64 INTMAX_T; 31typedef __sanitizer::u64 UINTMAX_T; 32typedef __sanitizer::OFF_T OFF_T; 33typedef __sanitizer::OFF64_T OFF64_T; 34 35// How to add an interceptor: 36// Suppose you need to wrap/replace system function (generally, from libc): 37// int foo(const char *bar, double baz); 38// You'll need to: 39// 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in 40// your source file. See the notes below for cases when 41// INTERCEPTOR_WITH_SUFFIX(...) should be used instead. 42// 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo". 43// INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was 44// intercepted successfully. 45// You can access original function by calling REAL(foo)(bar, baz). 46// By default, REAL(foo) will be visible only inside your interceptor, and if 47// you want to use it in other parts of RTL, you'll need to: 48// 3a) add DECLARE_REAL(int, foo, const char*, double) to a 49// header file. 50// However, if the call "INTERCEPT_FUNCTION(foo)" and definition for 51// INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to: 52// 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double) 53// to a header file. 54 55// Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or 56// DECLARE_REAL(...) are located inside namespaces. 57// 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to 58// effectively redirect calls from "foo" to "zoo". In this case 59// you aren't required to implement 60// INTERCEPTOR(int, foo, const char *bar, double baz) {...} 61// but instead you'll have to add 62// DECLARE_REAL(int, foo, const char *bar, double baz) in your 63// source file (to define a pointer to overriden function). 64// 3. Some Mac functions have symbol variants discriminated by 65// additional suffixes, e.g. _$UNIX2003 (see 66// https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html 67// for more details). To intercept such functions you need to use the 68// INTERCEPTOR_WITH_SUFFIX(...) macro. 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 SANITIZER_MAC 92#include <sys/cdefs.h> // For __DARWIN_ALIAS_C(). 93 94// Just a pair of pointers. 95struct interpose_substitution { 96 const __sanitizer::uptr replacement; 97 const __sanitizer::uptr original; 98}; 99 100// For a function foo() create a global pair of pointers { wrap_foo, foo } in 101// the __DATA,__interpose section. 102// As a result all the calls to foo() will be routed to wrap_foo() at runtime. 103#define INTERPOSER(func_name) __attribute__((used)) \ 104const interpose_substitution substitution_##func_name[] \ 105 __attribute__((section("__DATA, __interpose"))) = { \ 106 { reinterpret_cast<const uptr>(WRAP(func_name)), \ 107 reinterpret_cast<const uptr>(func_name) } \ 108} 109 110// For a function foo() and a wrapper function bar() create a global pair 111// of pointers { bar, foo } in the __DATA,__interpose section. 112// As a result all the calls to foo() will be routed to bar() at runtime. 113#define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \ 114const interpose_substitution substitution_##func_name[] \ 115 __attribute__((section("__DATA, __interpose"))) = { \ 116 { reinterpret_cast<const uptr>(wrapper_name), \ 117 reinterpret_cast<const uptr>(func_name) } \ 118} 119 120# define WRAP(x) wrap_##x 121# define WRAPPER_NAME(x) "wrap_"#x 122# define INTERCEPTOR_ATTRIBUTE 123# define DECLARE_WRAPPER(ret_type, func, ...) 124 125#elif SANITIZER_WINDOWS 126# define WRAP(x) __asan_wrap_##x 127# define WRAPPER_NAME(x) "__asan_wrap_"#x 128# define INTERCEPTOR_ATTRIBUTE __declspec(dllexport) 129# define DECLARE_WRAPPER(ret_type, func, ...) \ 130 extern "C" ret_type func(__VA_ARGS__); 131# define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \ 132 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__); 133#elif SANITIZER_RTEMS 134# define WRAP(x) x 135# define WRAPPER_NAME(x) #x 136# define INTERCEPTOR_ATTRIBUTE 137# define DECLARE_WRAPPER(ret_type, func, ...) 138#elif SANITIZER_FREEBSD || SANITIZER_NETBSD 139# define WRAP(x) __interceptor_ ## x 140# define WRAPPER_NAME(x) "__interceptor_" #x 141# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 142// FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher 143// priority than weak ones so weak aliases won't work for indirect calls 144// in position-independent (-fPIC / -fPIE) mode. 145# define DECLARE_WRAPPER(ret_type, func, ...) \ 146 extern "C" ret_type func(__VA_ARGS__) \ 147 __attribute__((alias("__interceptor_" #func), visibility("default"))); 148#elif !SANITIZER_FUCHSIA 149# define WRAP(x) __interceptor_ ## x 150# define WRAPPER_NAME(x) "__interceptor_" #x 151# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 152# define DECLARE_WRAPPER(ret_type, func, ...) \ 153 extern "C" ret_type func(__VA_ARGS__) \ 154 __attribute__((weak, alias("__interceptor_" #func), visibility("default"))); 155#endif 156 157#if SANITIZER_FUCHSIA 158// There is no general interception at all on Fuchsia. 159// Sanitizer runtimes just define functions directly to preempt them, 160// and have bespoke ways to access the underlying libc functions. 161# include <zircon/sanitizer.h> 162# define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default"))) 163# define REAL(x) __unsanitized_##x 164# define DECLARE_REAL(ret_type, func, ...) 165#elif SANITIZER_RTEMS 166# define REAL(x) __real_ ## x 167# define DECLARE_REAL(ret_type, func, ...) \ 168 extern "C" ret_type REAL(func)(__VA_ARGS__); 169#elif !SANITIZER_MAC 170# define PTR_TO_REAL(x) real_##x 171# define REAL(x) __interception::PTR_TO_REAL(x) 172# define FUNC_TYPE(x) x##_type 173 174# define DECLARE_REAL(ret_type, func, ...) \ 175 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 176 namespace __interception { \ 177 extern FUNC_TYPE(func) PTR_TO_REAL(func); \ 178 } 179# define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src) 180#else // SANITIZER_MAC 181# define REAL(x) x 182# define DECLARE_REAL(ret_type, func, ...) \ 183 extern "C" ret_type func(__VA_ARGS__); 184# define ASSIGN_REAL(x, y) 185#endif // SANITIZER_MAC 186 187#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS 188# define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \ 189 DECLARE_REAL(ret_type, func, __VA_ARGS__) \ 190 extern "C" ret_type WRAP(func)(__VA_ARGS__); 191// Declare an interceptor and its wrapper defined in a different translation 192// unit (ex. asm). 193# define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...) \ 194 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 195 extern "C" ret_type func(__VA_ARGS__); 196#else 197# define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) 198# define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...) 199#endif 200 201// Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR 202// macros does its job. In exceptional cases you may need to call REAL(foo) 203// without defining INTERCEPTOR(..., foo, ...). For example, if you override 204// foo with an interceptor for other function. 205#if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS 206# define DEFINE_REAL(ret_type, func, ...) \ 207 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \ 208 namespace __interception { \ 209 FUNC_TYPE(func) PTR_TO_REAL(func); \ 210 } 211#else 212# define DEFINE_REAL(ret_type, func, ...) 213#endif 214 215#if SANITIZER_FUCHSIA 216 217// We need to define the __interceptor_func name just to get 218// sanitizer_common/scripts/gen_dynamic_list.py to export func. 219// But we don't need to export __interceptor_func to get that. 220#define INTERCEPTOR(ret_type, func, ...) \ 221 extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \ 222 __interceptor_##func(__VA_ARGS__); \ 223 extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__) 224 225#elif !SANITIZER_MAC 226 227#define INTERCEPTOR(ret_type, func, ...) \ 228 DEFINE_REAL(ret_type, func, __VA_ARGS__) \ 229 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \ 230 extern "C" \ 231 INTERCEPTOR_ATTRIBUTE \ 232 ret_type WRAP(func)(__VA_ARGS__) 233 234// We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now. 235#define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 236 INTERCEPTOR(ret_type, func, __VA_ARGS__) 237 238#else // SANITIZER_MAC 239 240#define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \ 241 extern "C" ret_type func(__VA_ARGS__) suffix; \ 242 extern "C" ret_type WRAP(func)(__VA_ARGS__); \ 243 INTERPOSER(func); \ 244 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__) 245 246#define INTERCEPTOR(ret_type, func, ...) \ 247 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__) 248 249#define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \ 250 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__) 251 252// Override |overridee| with |overrider|. 253#define OVERRIDE_FUNCTION(overridee, overrider) \ 254 INTERPOSER_2(overridee, WRAP(overrider)) 255#endif 256 257#if SANITIZER_WINDOWS 258# define INTERCEPTOR_WINAPI(ret_type, func, ...) \ 259 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \ 260 namespace __interception { \ 261 FUNC_TYPE(func) PTR_TO_REAL(func); \ 262 } \ 263 extern "C" \ 264 INTERCEPTOR_ATTRIBUTE \ 265 ret_type __stdcall WRAP(func)(__VA_ARGS__) 266#endif 267 268// ISO C++ forbids casting between pointer-to-function and pointer-to-object, 269// so we use casting via an integral type __interception::uptr, 270// assuming that system is POSIX-compliant. Using other hacks seem 271// challenging, as we don't even pass function type to 272// INTERCEPT_FUNCTION macro, only its name. 273namespace __interception { 274#if defined(_WIN64) 275typedef unsigned long long uptr; 276#else 277typedef unsigned long uptr; 278#endif // _WIN64 279} // namespace __interception 280 281#define INCLUDED_FROM_INTERCEPTION_LIB 282 283#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \ 284 SANITIZER_OPENBSD || SANITIZER_SOLARIS 285 286# include "interception_linux.h" 287# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) 288# define INTERCEPT_FUNCTION_VER(func, symver) \ 289 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) 290#elif SANITIZER_MAC 291# include "interception_mac.h" 292# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func) 293# define INTERCEPT_FUNCTION_VER(func, symver) \ 294 INTERCEPT_FUNCTION_VER_MAC(func, symver) 295#elif SANITIZER_WINDOWS 296# include "interception_win.h" 297# define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func) 298# define INTERCEPT_FUNCTION_VER(func, symver) \ 299 INTERCEPT_FUNCTION_VER_WIN(func, symver) 300#endif 301 302#undef INCLUDED_FROM_INTERCEPTION_LIB 303 304#endif // INTERCEPTION_H 305