libsanitizer/interception/interception.h

   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_APPLE &&      \
  20     !SANITIZER_NETBSD && !SANITIZER_WINDOWS && !SANITIZER_FUCHSIA && \
  21     !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)
  27 typedef __sanitizer::uptr    SIZE_T;
  28 typedef __sanitizer::sptr    SSIZE_T;
  29 typedef __sanitizer::sptr    PTRDIFF_T;
  30 typedef __sanitizer::s64     INTMAX_T;
  31 typedef __sanitizer::u64     UINTMAX_T;
  32 typedef __sanitizer::OFF_T   OFF_T;
  33 typedef __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_APPLE
  92 #include <sys/cdefs.h>  // For __DARWIN_ALIAS_C().
  93
  94 // Just a pair of pointers.
  95 struct 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)) \
 104 const 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)) \
 114 const 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_FREEBSD || SANITIZER_NETBSD
 134 # define WRAP(x) __interceptor_ ## x
 135 # define WRAPPER_NAME(x) "__interceptor_" #x
 136 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 137 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
 138 // priority than weak ones so weak aliases won't work for indirect calls
 139 // in position-independent (-fPIC / -fPIE) mode.
 140 # define DECLARE_WRAPPER(ret_type, func, ...) \
 141      extern "C" ret_type func(__VA_ARGS__) \
 142      __attribute__((alias("__interceptor_" #func), visibility("default")));
 143 #elif !SANITIZER_FUCHSIA
 144 # define WRAP(x) __interceptor_ ## x
 145 # define WRAPPER_NAME(x) "__interceptor_" #x
 146 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 147 # define DECLARE_WRAPPER(ret_type, func, ...) \
 148     extern "C" ret_type func(__VA_ARGS__) \
 149     __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
 150 #endif
 151
 152 #if SANITIZER_FUCHSIA
 153 // There is no general interception at all on Fuchsia.
 154 // Sanitizer runtimes just define functions directly to preempt them,
 155 // and have bespoke ways to access the underlying libc functions.
 156 # include <zircon/sanitizer.h>
 157 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 158 # define REAL(x) __unsanitized_##x
 159 # define DECLARE_REAL(ret_type, func, ...)
 160 #elif !SANITIZER_APPLE
 161 # define PTR_TO_REAL(x) real_##x
 162 # define REAL(x) __interception::PTR_TO_REAL(x)
 163 # define FUNC_TYPE(x) x##_type
 164
 165 # define DECLARE_REAL(ret_type, func, ...) \
 166     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 167     namespace __interception { \
 168       extern FUNC_TYPE(func) PTR_TO_REAL(func); \
 169     }
 170 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
 171 #else  // SANITIZER_APPLE
 172 # define REAL(x) x
 173 # define DECLARE_REAL(ret_type, func, ...) \
 174     extern "C" ret_type func(__VA_ARGS__);
 175 # define ASSIGN_REAL(x, y)
 176 #endif  // SANITIZER_APPLE
 177
 178 #if !SANITIZER_FUCHSIA
 179 #  define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
 180     DECLARE_REAL(ret_type, func, __VA_ARGS__)               \
 181     extern "C" ret_type WRAP(func)(__VA_ARGS__);
 182 // Declare an interceptor and its wrapper defined in a different translation
 183 // unit (ex. asm).
 184 # define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...)    \
 185   extern "C" ret_type WRAP(func)(__VA_ARGS__); \
 186   extern "C" ret_type func(__VA_ARGS__);
 187 #else
 188 # define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...)
 189 # define DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(ret_type, func, ...)
 190 #endif
 191
 192 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
 193 // macros does its job. In exceptional cases you may need to call REAL(foo)
 194 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
 195 // foo with an interceptor for other function.
 196 #if !SANITIZER_APPLE && !SANITIZER_FUCHSIA
 197 #  define DEFINE_REAL(ret_type, func, ...)            \
 198     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 199     namespace __interception {                        \
 200     FUNC_TYPE(func) PTR_TO_REAL(func);                \
 201     }
 202 #else
 203 # define DEFINE_REAL(ret_type, func, ...)
 204 #endif
 205
 206 #if SANITIZER_FUCHSIA
 207
 208 // We need to define the __interceptor_func name just to get
 209 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
 210 // But we don't need to export __interceptor_func to get that.
 211 #define INTERCEPTOR(ret_type, func, ...)                                \
 212   extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \
 213       __interceptor_##func(__VA_ARGS__);                                \
 214   extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
 215
 216 #elif !SANITIZER_APPLE
 217
 218 #define INTERCEPTOR(ret_type, func, ...) \
 219   DEFINE_REAL(ret_type, func, __VA_ARGS__) \
 220   DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
 221   extern "C" \
 222   INTERCEPTOR_ATTRIBUTE \
 223   ret_type WRAP(func)(__VA_ARGS__)
 224
 225 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now.
 226 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 227   INTERCEPTOR(ret_type, func, __VA_ARGS__)
 228
 229 #else  // SANITIZER_APPLE
 230
 231 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
 232   extern "C" ret_type func(__VA_ARGS__) suffix; \
 233   extern "C" ret_type WRAP(func)(__VA_ARGS__); \
 234   INTERPOSER(func); \
 235   extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__)
 236
 237 #define INTERCEPTOR(ret_type, func, ...) \
 238   INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__)
 239
 240 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 241   INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__)
 242
 243 // Override |overridee| with |overrider|.
 244 #define OVERRIDE_FUNCTION(overridee, overrider) \
 245   INTERPOSER_2(overridee, WRAP(overrider))
 246 #endif
 247
 248 #if SANITIZER_WINDOWS
 249 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
 250     typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
 251     namespace __interception { \
 252       FUNC_TYPE(func) PTR_TO_REAL(func); \
 253     } \
 254     extern "C" \
 255     INTERCEPTOR_ATTRIBUTE \
 256     ret_type __stdcall WRAP(func)(__VA_ARGS__)
 257 #endif
 258
 259 // ISO C++ forbids casting between pointer-to-function and pointer-to-object,
 260 // so we use casting via an integral type __interception::uptr,
 261 // assuming that system is POSIX-compliant. Using other hacks seem
 262 // challenging, as we don't even pass function type to
 263 // INTERCEPT_FUNCTION macro, only its name.
 264 namespace __interception {
 265 #if defined(_WIN64)
 266 typedef unsigned long long uptr;
 267 #else
 268 typedef unsigned long uptr;
 269 #endif  // _WIN64
 270 }  // namespace __interception
 271
 272 #define INCLUDED_FROM_INTERCEPTION_LIB
 273
 274 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
 275     SANITIZER_SOLARIS
 276
 277 # include "interception_linux.h"
 278 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
 279 # define INTERCEPT_FUNCTION_VER(func, symver) \
 280     INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
 281 #elif SANITIZER_APPLE
 282 # include "interception_mac.h"
 283 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
 284 # define INTERCEPT_FUNCTION_VER(func, symver) \
 285     INTERCEPT_FUNCTION_VER_MAC(func, symver)
 286 #elif SANITIZER_WINDOWS
 287 # include "interception_win.h"
 288 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
 289 # define INTERCEPT_FUNCTION_VER(func, symver) \
 290     INTERCEPT_FUNCTION_VER_WIN(func, symver)
 291 #endif
 292
 293 #undef INCLUDED_FROM_INTERCEPTION_LIB
 294
 295 #endif  // INTERCEPTION_H