1 //===-- interception.h ------------------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
12 // Machinery for providing replacements/wrappers for system functions.
13 //===----------------------------------------------------------------------===//
15 #ifndef INTERCEPTION_H
16 #define INTERCEPTION_H
18 #include "sanitizer_common/sanitizer_internal_defs.h"
20 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
21 !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \
22 !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS
23 # error "Interception doesn't work on this operating system."
26 // These typedefs should be used only in the interceptor definitions to replace
27 // the standard system types (e.g. SSIZE_T instead of ssize_t)
28 typedef __sanitizer::uptr SIZE_T;
29 typedef __sanitizer::sptr SSIZE_T;
30 typedef __sanitizer::sptr PTRDIFF_T;
31 typedef __sanitizer::s64 INTMAX_T;
32 typedef __sanitizer::u64 UINTMAX_T;
33 typedef __sanitizer::OFF_T OFF_T;
34 typedef __sanitizer::OFF64_T OFF64_T;
36 // How to add an interceptor:
37 // Suppose you need to wrap/replace system function (generally, from libc):
38 // int foo(const char *bar, double baz);
40 // 1) define INTERCEPTOR(int, foo, const char *bar, double baz) { ... } in
41 // your source file. See the notes below for cases when
42 // INTERCEPTOR_WITH_SUFFIX(...) should be used instead.
43 // 2) Call "INTERCEPT_FUNCTION(foo)" prior to the first call of "foo".
44 // INTERCEPT_FUNCTION(foo) evaluates to "true" iff the function was
45 // intercepted successfully.
46 // You can access original function by calling REAL(foo)(bar, baz).
47 // By default, REAL(foo) will be visible only inside your interceptor, and if
48 // you want to use it in other parts of RTL, you'll need to:
49 // 3a) add DECLARE_REAL(int, foo, const char*, double) to a
51 // However, if the call "INTERCEPT_FUNCTION(foo)" and definition for
52 // INTERCEPTOR(..., foo, ...) are in different files, you'll instead need to:
53 // 3b) add DECLARE_REAL_AND_INTERCEPTOR(int, foo, const char*, double)
56 // Notes: 1. Things may not work properly if macro INTERCEPTOR(...) {...} or
57 // DECLARE_REAL(...) are located inside namespaces.
58 // 2. On Mac you can also use: "OVERRIDE_FUNCTION(foo, zoo)" to
59 // effectively redirect calls from "foo" to "zoo". In this case
60 // you aren't required to implement
61 // INTERCEPTOR(int, foo, const char *bar, double baz) {...}
62 // but instead you'll have to add
63 // DECLARE_REAL(int, foo, const char *bar, double baz) in your
64 // source file (to define a pointer to overriden function).
65 // 3. Some Mac functions have symbol variants discriminated by
66 // additional suffixes, e.g. _$UNIX2003 (see
67 // https://developer.apple.com/library/mac/#releasenotes/Darwin/SymbolVariantsRelNotes/index.html
68 // for more details). To intercept such functions you need to use the
69 // INTERCEPTOR_WITH_SUFFIX(...) macro.
72 // To replace system functions on Linux we just need to declare functions
73 // with same names in our library and then obtain the real function pointers
75 // There is one complication. A user may also intercept some of the functions
76 // we intercept. To resolve this we declare our interceptors with __interceptor_
77 // prefix, and then make actual interceptors weak aliases to __interceptor_
80 // This is not so on Mac OS, where the two-level namespace makes
81 // our replacement functions invisible to other libraries. This may be overcomed
82 // using the DYLD_FORCE_FLAT_NAMESPACE, but some errors loading the shared
83 // libraries in Chromium were noticed when doing so.
84 // Instead we create a dylib containing a __DATA,__interpose section that
85 // associates library functions with their wrappers. When this dylib is
86 // preloaded before an executable using DYLD_INSERT_LIBRARIES, it routes all
87 // the calls to interposed functions done through stubs to the wrapper
89 // As it's decided at compile time which functions are to be intercepted on Mac,
90 // INTERCEPT_FUNCTION() is effectively a no-op on this system.
93 #include <sys/cdefs.h> // For __DARWIN_ALIAS_C().
95 // Just a pair of pointers.
96 struct interpose_substitution {
97 const __sanitizer::uptr replacement;
98 const __sanitizer::uptr original;
101 // For a function foo() create a global pair of pointers { wrap_foo, foo } in
102 // the __DATA,__interpose section.
103 // As a result all the calls to foo() will be routed to wrap_foo() at runtime.
104 #define INTERPOSER(func_name) __attribute__((used)) \
105 const interpose_substitution substitution_##func_name[] \
106 __attribute__((section("__DATA, __interpose"))) = { \
107 { reinterpret_cast<const uptr>(WRAP(func_name)), \
108 reinterpret_cast<const uptr>(func_name) } \
111 // For a function foo() and a wrapper function bar() create a global pair
112 // of pointers { bar, foo } in the __DATA,__interpose section.
113 // As a result all the calls to foo() will be routed to bar() at runtime.
114 #define INTERPOSER_2(func_name, wrapper_name) __attribute__((used)) \
115 const interpose_substitution substitution_##func_name[] \
116 __attribute__((section("__DATA, __interpose"))) = { \
117 { reinterpret_cast<const uptr>(wrapper_name), \
118 reinterpret_cast<const uptr>(func_name) } \
121 # define WRAP(x) wrap_##x
122 # define WRAPPER_NAME(x) "wrap_"#x
123 # define INTERCEPTOR_ATTRIBUTE
124 # define DECLARE_WRAPPER(ret_type, func, ...)
126 #elif SANITIZER_WINDOWS
127 # define WRAP(x) __asan_wrap_##x
128 # define WRAPPER_NAME(x) "__asan_wrap_"#x
129 # define INTERCEPTOR_ATTRIBUTE __declspec(dllexport)
130 # define DECLARE_WRAPPER(ret_type, func, ...) \
131 extern "C" ret_type func(__VA_ARGS__);
132 # define DECLARE_WRAPPER_WINAPI(ret_type, func, ...) \
133 extern "C" __declspec(dllimport) ret_type __stdcall func(__VA_ARGS__);
134 #elif SANITIZER_RTEMS
136 # define WRAPPER_NAME(x) #x
137 # define INTERCEPTOR_ATTRIBUTE
138 # define DECLARE_WRAPPER(ret_type, func, ...)
139 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
140 # define WRAP(x) __interceptor_ ## x
141 # define WRAPPER_NAME(x) "__interceptor_" #x
142 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
143 // FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
144 // priority than weak ones so weak aliases won't work for indirect calls
145 // in position-independent (-fPIC / -fPIE) mode.
146 # define DECLARE_WRAPPER(ret_type, func, ...) \
147 extern "C" ret_type func(__VA_ARGS__) \
148 __attribute__((alias("__interceptor_" #func), visibility("default")));
149 #elif !SANITIZER_FUCHSIA
150 # define WRAP(x) __interceptor_ ## x
151 # define WRAPPER_NAME(x) "__interceptor_" #x
152 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
153 # define DECLARE_WRAPPER(ret_type, func, ...) \
154 extern "C" ret_type func(__VA_ARGS__) \
155 __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
158 #if SANITIZER_FUCHSIA
159 // There is no general interception at all on Fuchsia.
160 // Sanitizer runtimes just define functions directly to preempt them,
161 // and have bespoke ways to access the underlying libc functions.
162 # include <zircon/sanitizer.h>
163 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
164 # define REAL(x) __unsanitized_##x
165 # define DECLARE_REAL(ret_type, func, ...)
166 #elif SANITIZER_RTEMS
167 # define REAL(x) __real_ ## x
168 # define DECLARE_REAL(ret_type, func, ...) \
169 extern "C" ret_type REAL(func)(__VA_ARGS__);
171 # define PTR_TO_REAL(x) real_##x
172 # define REAL(x) __interception::PTR_TO_REAL(x)
173 # define FUNC_TYPE(x) x##_type
175 # define DECLARE_REAL(ret_type, func, ...) \
176 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
177 namespace __interception { \
178 extern FUNC_TYPE(func) PTR_TO_REAL(func); \
180 # define ASSIGN_REAL(dst, src) REAL(dst) = REAL(src)
181 #else // SANITIZER_MAC
183 # define DECLARE_REAL(ret_type, func, ...) \
184 extern "C" ret_type func(__VA_ARGS__);
185 # define ASSIGN_REAL(x, y)
186 #endif // SANITIZER_MAC
188 #if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
189 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...) \
190 DECLARE_REAL(ret_type, func, __VA_ARGS__) \
191 extern "C" ret_type WRAP(func)(__VA_ARGS__);
193 #define DECLARE_REAL_AND_INTERCEPTOR(ret_type, func, ...)
196 // Generally, you don't need to use DEFINE_REAL by itself, as INTERCEPTOR
197 // macros does its job. In exceptional cases you may need to call REAL(foo)
198 // without defining INTERCEPTOR(..., foo, ...). For example, if you override
199 // foo with an interceptor for other function.
200 #if !SANITIZER_MAC && !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
201 # define DEFINE_REAL(ret_type, func, ...) \
202 typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
203 namespace __interception { \
204 FUNC_TYPE(func) PTR_TO_REAL(func); \
207 # define DEFINE_REAL(ret_type, func, ...)
210 #if SANITIZER_FUCHSIA
212 // We need to define the __interceptor_func name just to get
213 // sanitizer_common/scripts/gen_dynamic_list.py to export func.
214 // But we don't need to export __interceptor_func to get that.
215 #define INTERCEPTOR(ret_type, func, ...) \
216 extern "C"[[ gnu::alias(#func), gnu::visibility("hidden") ]] ret_type \
217 __interceptor_##func(__VA_ARGS__); \
218 extern "C" INTERCEPTOR_ATTRIBUTE ret_type func(__VA_ARGS__)
222 #define INTERCEPTOR(ret_type, func, ...) \
223 DEFINE_REAL(ret_type, func, __VA_ARGS__) \
224 DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
226 INTERCEPTOR_ATTRIBUTE \
227 ret_type WRAP(func)(__VA_ARGS__)
229 // We don't need INTERCEPTOR_WITH_SUFFIX on non-Darwin for now.
230 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
231 INTERCEPTOR(ret_type, func, __VA_ARGS__)
233 #else // SANITIZER_MAC
235 #define INTERCEPTOR_ZZZ(suffix, ret_type, func, ...) \
236 extern "C" ret_type func(__VA_ARGS__) suffix; \
237 extern "C" ret_type WRAP(func)(__VA_ARGS__); \
239 extern "C" INTERCEPTOR_ATTRIBUTE ret_type WRAP(func)(__VA_ARGS__)
241 #define INTERCEPTOR(ret_type, func, ...) \
242 INTERCEPTOR_ZZZ(/*no symbol variants*/, ret_type, func, __VA_ARGS__)
244 #define INTERCEPTOR_WITH_SUFFIX(ret_type, func, ...) \
245 INTERCEPTOR_ZZZ(__DARWIN_ALIAS_C(func), ret_type, func, __VA_ARGS__)
247 // Override |overridee| with |overrider|.
248 #define OVERRIDE_FUNCTION(overridee, overrider) \
249 INTERPOSER_2(overridee, WRAP(overrider))
252 #if SANITIZER_WINDOWS
253 # define INTERCEPTOR_WINAPI(ret_type, func, ...) \
254 typedef ret_type (__stdcall *FUNC_TYPE(func))(__VA_ARGS__); \
255 namespace __interception { \
256 FUNC_TYPE(func) PTR_TO_REAL(func); \
259 INTERCEPTOR_ATTRIBUTE \
260 ret_type __stdcall WRAP(func)(__VA_ARGS__)
263 // ISO C++ forbids casting between pointer-to-function and pointer-to-object,
264 // so we use casting via an integral type __interception::uptr,
265 // assuming that system is POSIX-compliant. Using other hacks seem
266 // challenging, as we don't even pass function type to
267 // INTERCEPT_FUNCTION macro, only its name.
268 namespace __interception {
270 typedef unsigned long long uptr; // NOLINT
272 typedef unsigned long uptr; // NOLINT
274 } // namespace __interception
276 #define INCLUDED_FROM_INTERCEPTION_LIB
278 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
279 SANITIZER_OPENBSD || SANITIZER_SOLARIS
281 # include "interception_linux.h"
282 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
283 # define INTERCEPT_FUNCTION_VER(func, symver) \
284 INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver)
286 # include "interception_mac.h"
287 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_MAC(func)
288 # define INTERCEPT_FUNCTION_VER(func, symver) \
289 INTERCEPT_FUNCTION_VER_MAC(func, symver)
290 #elif SANITIZER_WINDOWS
291 # include "interception_win.h"
292 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_WIN(func)
293 # define INTERCEPT_FUNCTION_VER(func, symver) \
294 INTERCEPT_FUNCTION_VER_WIN(func, symver)
297 #undef INCLUDED_FROM_INTERCEPTION_LIB
299 #endif // INTERCEPTION_H