lib/interception/interception.h

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