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