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 #include "sanitizer_common/sanitizer_internal_defs.h"
  17
  18 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
  19     !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \
  20     !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS
  21 # error "Interception doesn't work on this operating system."
  22 #endif
  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::u64     UINTMAX_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 SANITIZER_MAC
  91 #include <sys/cdefs.h>  // For __DARWIN_ALIAS_C().
  92
  93 // Just a pair of pointers.
  94 struct interpose_substitution {
  95   const __sanitizer::uptr replacement;
  96   const __sanitizer::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 SANITIZER_WINDOWS
 125 # define WRAP(x) __asan_wrap_##x
 126 # define WRAPPER_NAME(x) "__asan_wrap_"#x
 127 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport)
 128 # define DECLARE_WRAPPER(ret_type, func, ...) \
 129     extern "C" ret_type func(__VA_ARGS__);
 130 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \
 131     extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__);
 132 #elif SANITIZER_RTEMS
 133 # define WRAP(x) x
 134 # define WRAPPER_NAME(x) #x
 135 # define INTERCEPTOR_ATTRIBUTE
 136 # define DECLARE_WRAPPER(ret_type, func, ...)
 137 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
 138 # define WRAP(x) __interceptor_ ## x
 139 # define WRAPPER_NAME(x) "__interceptor_" #x
 140 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 141 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
 142 // priority than weak ones so weak aliases won't work for indirect calls
 143 // in position-independent (-fPIC / -fPIE) mode.
 144 # define DECLARE_WRAPPER(ret_type, func, ...) \
 145      extern "C" ret_type func(__VA_ARGS__) \
 146      __attribute__((alias("__interceptor_" #func), visibility("default")));
 147 #elif !SANITIZER_FUCHSIA
 148 # define WRAP(x) __interceptor_ ## x
 149 # define WRAPPER_NAME(x) "__interceptor_" #x
 150 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 151 # define DECLARE_WRAPPER(ret_type, func, ...) \
 152     extern "C" ret_type func(__VA_ARGS__) \
 153     __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
 154 #endif
 155
 156 #if SANITIZER_FUCHSIA
 157 // There is no general interception at all on Fuchsia.
 158 // Sanitizer runtimes just define functions directly to preempt them,
 159 // and have bespoke ways to access the underlying libc functions.
 160 # include <zircon/sanitizer.h>
 161 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
 162 # define REAL(x) __unsanitized_##x
 163 # define DECLARE_REAL(ret_type, func, ...)
 164 #elif SANITIZER_RTEMS
 165 # define REAL(x) __real_ ## x
 166 # define DECLARE_REAL(ret_type, func, ...) \
 167     extern "C" ret_type REAL(func)(__VA_ARGS__);
 168 #elif !SANITIZER_MAC
 169 # define PTR_TO_REAL(x) real_##x
 170 # define REAL(x) __interception::PTR_TO_REAL(x)
 171 # define FUNC_TYPE(x) x##_type
 172
 173 # define DECLARE_REAL(ret_type, func, ...) \
 174     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 175     namespace __interception { \
 176       extern FUNC_TYPE(func) PTR_TO_REAL(func); \
 177     }
 178 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
 179 #else  // SANITIZER_MAC
 180 # define REAL(x) x
 181 # define DECLARE_REAL(ret_type, func, ...) \
 182     extern "C" ret_type func(__VA_ARGS__);
 183 # define ASSIGN_REAL(x, y)
 184 #endif  // SANITIZER_MAC
 185
 186 #if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 187 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
 188   DECLARE_REAL(ret_type, func, __VA_ARGS__) \
 189   extern "C" ret_type WRAP(func)(__VA_ARGS__);
 190 #else
 191 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...)
 192 #endif
 193
 194 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
 195 // macros does its job. In exceptional cases you may need to call REAL(foo)
 196 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
 197 // foo with an interceptor for other function.
 198 #if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 199 # define DEFINE_REAL(ret_type, func, ...) \
 200     typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
 201     namespace __interception { \
 202       FUNC_TYPE(func) PTR_TO_REAL(func); \
 203     }
 204 #else
 205 # define DEFINE_REAL(ret_type, func, ...)
 206 #endif
 207
 208 #if SANITIZER_FUCHSIA
 209
 210 // We need to define the __interceptor_func name just to get
 211 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
 212 // But we don't need to export __interceptor_func to get that.
 213 #define INTERCEPTOR(ret_type, func, ...)                                \
 214   extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \
 215       __interceptor_##func(__VA_ARGS__);                                \
 216   extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
 217
 218 #elif !SANITIZER_MAC
 219
 220 #define INTERCEPTOR(ret_type, func, ...) \
 221   DEFINE_REAL(ret_type, func, __VA_ARGS__) \
 222   DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
 223   extern "C" \
 224   INTERCEPTOR_ATTRIBUTE \
 225   ret_type WRAP(func)(__VA_ARGS__)
 226
 227 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now.
 228 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 229   INTERCEPTOR(ret_type, func, __VA_ARGS__)
 230
 231 #else  // SANITIZER_MAC
 232
 233 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
 234   extern "C" ret_type func(__VA_ARGS__) suffix; \
 235   extern "C" ret_type WRAP(func)(__VA_ARGS__); \
 236   INTERPOSER(func); \
 237   extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__)
 238
 239 #define INTERCEPTOR(ret_type, func, ...) \
 240   INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__)
 241
 242 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
 243   INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__)
 244
 245 // Override |overridee| with |overrider|.
 246 #define OVERRIDE_FUNCTION(overridee, overrider) \
 247   INTERPOSER_2(overridee, WRAP(overrider))
 248 #endif
 249
 250 #if SANITIZER_WINDOWS
 251 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
 252     typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
 253     namespace __interception { \
 254       FUNC_TYPE(func) PTR_TO_REAL(func); \
 255     } \
 256     extern "C" \
 257     INTERCEPTOR_ATTRIBUTE \
 258     ret_type __stdcall WRAP(func)(__VA_ARGS__)
 259 #endif
 260
 261 // ISO C++ forbids casting between pointer-to-function and pointer-to-object,
 262 // so we use casting via an integral type __interception::uptr,
 263 // assuming that system is POSIX-compliant. Using other hacks seem
 264 // challenging, as we don't even pass function type to
 265 // INTERCEPT_FUNCTION macro, only its name.
 266 namespace __interception {
 267 #if defined(_WIN64)
 268 typedef unsigned long long uptr;  // NOLINT
 269 #else
 270 typedef unsigned long uptr;  // NOLINT
 271 #endif  // _WIN64
 272 }  // namespace __interception
 273
 274 #define INCLUDED_FROM_INTERCEPTION_LIB
 275
 276 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
 277     SANITIZER_OPENBSD || SANITIZER_SOLARIS
 278
 279 # include "interception_linux.h"
 280 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
 281 # define INTERCEPT_FUNCTION_VER(func, symver) \
 282     INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
 283 #elif SANITIZER_MAC
 284 # include "interception_mac.h"
 285 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
 286 # define INTERCEPT_FUNCTION_VER(func, symver) \
 287     INTERCEPT_FUNCTION_VER_MAC(func, symver)
 288 #elif SANITIZER_WINDOWS
 289 # include "interception_win.h"
 290 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
 291 # define INTERCEPT_FUNCTION_VER(func, symver) \
 292     INTERCEPT_FUNCTION_VER_WIN(func, symver)
 293 #endif
 294
 295 #undef INCLUDED_FROM_INTERCEPTION_LIB
 296
 297 #endif  // INTERCEPTION_H