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