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_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)
  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_MAC
  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_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.
 273 namespace __interception {
 274 #if defined(_WIN64)
 275 typedef unsigned long long uptr;
 276 #else
 277 typedef 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