libsanitizer/interception/interception.h

   1 //===-- interception.h ------------------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // Machinery for providing replacements/wrappers for system functions.
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef INTERCEPTION_H
  14 #define INTERCEPTION_H
  15
  16 #if !defined(__linux__) && !defined(__FreeBSD__) && !defined(__APPLE__) && \
  17     !defined(__NetBSD__) && !defined(_WIN32) && !defined(__Fuchsia__)
  18 # error "Interception doesn't work on this operating system."
  19 #endif
  20
  21 #include "sanitizer_common/sanitizer_internal_defs.h"
  22
  23 // These typedefs should be used only in the interceptor definitions to replace
  24 // the standard system types (e.g. SSIZE_T instead of ssize_t)
  25 typedef __sanitizer::uptr    SIZE_T;
  26 typedef __sanitizer::sptr    SSIZE_T;
  27 typedef __sanitizer::sptr    PTRDIFF_T;
  28 typedef __sanitizer::s64     INTMAX_T;
  29 typedef __sanitizer::OFF_T   OFF_T;
  30 typedef __sanitizer::OFF64_T OFF64_T;
  31
  32 // How to add an interceptor:
  33 // Suppose you need to wrap/replace system function (generally, from libc):
  34 //      int foo(const char *bar, double baz);
  35 // You'll need to:
  36 //      1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in
  37 //         your source file. See the notes below for cases when
  38 //         INTERCEPTOR_WITH_SUFFIX(...) should be used instead.
  39 //      2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo".
  40 //         INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was
  41 //         intercepted successfully.
  42 // You can access original function by calling REAL(foo)(bar, baz).
  43 // By default, REAL(foo) will be visible only inside your interceptor, and if
  44 // you want to use it in other parts of RTL, you'll need to:
  45 //      3a) add DECLARE_REAL(int, foo, const char*, double) to a
  46 //          header file.
  47 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for
  48 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to:
  49 //      3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double)
  50 //          to a header file.
  51
  52 // Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or
  53 //           DECLARE_REAL(...) are located inside namespaces.
  54 //        2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to
  55 //           effectively redirect calls from "foo" to "zoo". In this case
  56 //           you aren't required to implement
  57 //           INTERCEPTOR(int, foo, const char *bar, double baz) {...}
  58 //           but instead you'll have to add
  59 //           DECLARE_REAL(int, foo, const char *bar, double baz) in your
  60 //           source file (to define a pointer to overriden function).
  61 //        3. Some Mac functions have symbol variants discriminated by
  62 //           additional suffixes, e.g. _$UNIX2003 (see
  63 //           https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html
  64 //           for more details). To intercept such functions you need to use the
  65 //           INTERCEPTOR_WITH_SUFFIX(...) macro.
  66
  67 // How it works:
  68 // To replace system functions on Linux we just need to declare functions
  69 // with same names in our library and then obtain the real function pointers
  70 // using dlsym().
  71 // There is one complication. A user may also intercept some of the functions
  72 // we intercept. To resolve this we declare our interceptors with __interceptor_
  73 // prefix, and then make actual interceptors weak aliases to __interceptor_
  74 // functions.
  75 //
  76 // This is not so on Mac OS, where the two-level namespace makes
  77 // our replacement functions invisible to other libraries. This may be overcomed
  78 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
  79 // libraries in Chromium were noticed when doing so.
  80 // Instead we create a dylib containing a __DATA,__interpose section that
  81 // associates library functions with their wrappers. When this dylib is
  82 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all
  83 // the calls to interposed functions done through stubs to the wrapper
  84 // functions.
  85 // As it's decided at compile time which functions are to be intercepted on Mac,
  86 // INTERCEPT_FUNCTION() is effectively a no-op on this system.
  87
  88 #if defined(__APPLE__)
  89 #include <sys/cdefs.h>  // For __DARWIN_ALIAS_C().
  90
  91 // Just a pair of pointers.
  92 struct interpose_substitution {
  93   const __sanitizer::uptr replacement;
  94   const __sanitizer::uptr original;
  95 };
  96
  97 // For a function foo() create a global pair of pointers { wrap_foo, foo } in
  98 // the __DATA,__interpose section.
  99 // As a result all the calls to foo() will be routed to wrap_foo() at runtime.
 100 #define INTERPOSER(func_name) __attribute__((used)) \
 101 const interpose_substitution substitution_##func_name[] \
 102     __attribute__((section("__DATA, __interpose"))) = { \
 103     { reinterpret_cast<const uptr>(WRAP(func_name)), \
 104       reinterpret_cast<const uptr>(func_name) } \
 105 }
 106
 107 // For a function foo() and a wrapper function bar() create a global pair
 108 // of pointers { bar, foo } in the __DATA,__interpose section.
 109 // As a result all the calls to foo() will be routed to bar() at runtime.
 110 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \
 111 const interpose_substitution substitution_##func_name[] \
 112     __attribute__((section("__DATA, __interpose"))) = { \
 113     { reinterpret_cast<const uptr>(wrapper_name), \
 114       reinterpret_cast<const uptr>(func_name) } \
 115 }
 116
 117 # define WRAP(x) wrap_##x
 118 # define WRAPPER_NAME(x) "wrap_"#x
 119 # define INTERCEPTOR_ATTRIBUTE
 120 # define DECLARE_WRAPPER(ret_type, func, ...)
 121
 122 #elif defined(_WIN32)
 123 # define WRAP(x) __asan_wrap_##x
 124 # define WRAPPER_NAME(x) "__asan_wrap_"#x
 125 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport)
 126 # define DECLARE_WRAPPER(ret_type, func, ...) \
 127     extern "C" ret_type func(__VA_ARGS__);
 128 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \
 129     extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__);
 130 #elif defined(__FreeBSD__) || defined(__NetBSD__)
 131 # define WRAP(x) __interceptor_ ## x
 132 # define WRAPPER_NAME(x) "__interceptor_" #x
 133 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 134 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
 135 // priority than weak ones so weak aliases won't work for indirect calls
 136 // in position-independent (-fPIC / -fPIE) mode.
 137 # define DECLARE_WRAPPER(ret_type, func, ...) \
 138      extern "C" ret_type func(__VA_ARGS__) \
 139      __attribute__((alias("__interceptor_" #func), visibility("default")));
 140 #elif !defined(__Fuchsia__)
 141 # define WRAP(x) __interceptor_ ## x
 142 # define WRAPPER_NAME(x) "__interceptor_" #x
 143 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 144 # define DECLARE_WRAPPER(ret_type, func, ...) \
 145     extern "C" ret_type func(__VA_ARGS__) \
 146     __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
 147 #endif
 148
 149 #if defined(__Fuchsia__)
 150 // There is no general interception at all on Fuchsia.
 151 // Sanitizer runtimes just define functions directly to preempt them,
 152 // and have bespoke ways to access the underlying libc functions.
 153 # include <zircon/sanitizer.h>
 154 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 155 # define REAL(x) __unsanitized_##x
 156 # define DECLARE_REAL(ret_type, func, ...)
 157 #elif !defined(__APPLE__)
 158 # define PTR_TO_REAL(x) real_##x
 159 # define REAL(x) __interception::PTR_TO_REAL(x)
 160 # define FUNC_TYPE(x) x##_f
 161
 162 # define DECLARE_REAL(ret_type, func, ...) \
 163     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 164     namespace __interception { \
 165       extern FUNC_TYPE(func) PTR_TO_REAL(func); \
 166     }
 167 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
 168 #else  // __APPLE__
 169 # define REAL(x) x
 170 # define DECLARE_REAL(ret_type, func, ...) \
 171     extern "C" ret_type func(__VA_ARGS__);
 172 # define ASSIGN_REAL(x, y)
 173 #endif  // __APPLE__
 174
 175 #if !defined(__Fuchsia__)
 176 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
 177   DECLARE_REAL(ret_type, func, __VA_ARGS__) \
 178   extern "C" ret_type WRAP(func)(__VA_ARGS__);
 179 #else
 180 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...)
 181 #endif
 182
 183 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
 184 // macros does its job. In exceptional cases you may need to call REAL(foo)
 185 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
 186 // foo with an interceptor for other function.
 187 #if !defined(__APPLE__) && !defined(__Fuchsia__)
 188 # define DEFINE_REAL(ret_type, func, ...) \
 189     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 190     namespace __interception { \
 191       FUNC_TYPE(func) PTR_TO_REAL(func); \
 192     }
 193 #else
 194 # define DEFINE_REAL(ret_type, func, ...)
 195 #endif
 196
 197 #if defined(__Fuchsia__)
 198
 199 // We need to define the __interceptor_func name just to get
 200 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
 201 // But we don't need to export __interceptor_func to get that.
 202 #define INTERCEPTOR(ret_type, func, ...)                                \
 203   extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \
 204       __interceptor_##func(__VA_ARGS__);                                \
 205   extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
 206
 207 #elif !defined(__APPLE__)
 208
 209 #define INTERCEPTOR(ret_type, func, ...) \
 210   DEFINE_REAL(ret_type, func, __VA_ARGS__) \
 211   DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
 212   extern "C" \
 213   INTERCEPTOR_ATTRIBUTE \
 214   ret_type WRAP(func)(__VA_ARGS__)
 215
 216 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now.
 217 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 218   INTERCEPTOR(ret_type, func, __VA_ARGS__)
 219
 220 #else  // __APPLE__
 221
 222 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
 223   extern "C" ret_type func(__VA_ARGS__) suffix; \
 224   extern "C" ret_type WRAP(func)(__VA_ARGS__); \
 225   INTERPOSER(func); \
 226   extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__)
 227
 228 #define INTERCEPTOR(ret_type, func, ...) \
 229   INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__)
 230
 231 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 232   INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__)
 233
 234 // Override |overridee| with |overrider|.
 235 #define OVERRIDE_FUNCTION(overridee, overrider) \
 236   INTERPOSER_2(overridee, WRAP(overrider))
 237 #endif
 238
 239 #if defined(_WIN32)
 240 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
 241     typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
 242     namespace __interception { \
 243       FUNC_TYPE(func) PTR_TO_REAL(func); \
 244     } \
 245     extern "C" \
 246     INTERCEPTOR_ATTRIBUTE \
 247     ret_type __stdcall WRAP(func)(__VA_ARGS__)
 248 #endif
 249
 250 // ISO C++ forbids casting between pointer-to-function and pointer-to-object,
 251 // so we use casting via an integral type __interception::uptr,
 252 // assuming that system is POSIX-compliant. Using other hacks seem
 253 // challenging, as we don't even pass function type to
 254 // INTERCEPT_FUNCTION macro, only its name.
 255 namespace __interception {
 256 #if defined(_WIN64)
 257 typedef unsigned long long uptr;  // NOLINT
 258 #else
 259 typedef unsigned long uptr;  // NOLINT
 260 #endif  // _WIN64
 261 }  // namespace __interception
 262
 263 #define INCLUDED_FROM_INTERCEPTION_LIB
 264
 265 #if defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__)
 266 # include "interception_linux.h"
 267 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
 268 # define INTERCEPT_FUNCTION_VER(func, symver) \
 269     INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
 270 #elif defined(__APPLE__)
 271 # include "interception_mac.h"
 272 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
 273 # define INTERCEPT_FUNCTION_VER(func, symver) \
 274     INTERCEPT_FUNCTION_VER_MAC(func, symver)
 275 #elif defined(_WIN32)
 276 # include "interception_win.h"
 277 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
 278 # define INTERCEPT_FUNCTION_VER(func, symver) \
 279     INTERCEPT_FUNCTION_VER_WIN(func, symver)
 280 #endif
 281
 282 #undef INCLUDED_FROM_INTERCEPTION_LIB
 283
 284 #endif  // INTERCEPTION_H