1 //===-- asan_mac.cc -------------------------------------------------------===//
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 // Mac-specific details.
13 //===----------------------------------------------------------------------===//
14
15 #include "sanitizer_common/sanitizer_platform.h"
16 #if SANITIZER_MAC
17
18 #include "asan_interceptors.h"
19 #include "asan_internal.h"
20 #include "asan_mapping.h"
21 #include "asan_stack.h"
22 #include "asan_thread.h"
23 #include "sanitizer_common/sanitizer_atomic.h"
24 #include "sanitizer_common/sanitizer_libc.h"
25 #include "sanitizer_common/sanitizer_mac.h"
26
27 #include <crt_externs.h> // for _NSGetArgv
28 #include <dlfcn.h> // for dladdr()
29 #include <mach-o/dyld.h>
30 #include <mach-o/loader.h>
31 #include <sys/mman.h>
32 #include <sys/resource.h>
33 #include <sys/sysctl.h>
34 #include <sys/ucontext.h>
35 #include <fcntl.h>
36 #include <pthread.h>
37 #include <stdlib.h> // for free()
38 #include <unistd.h>
39 #include <libkern/OSAtomic.h>
40
41 namespace __asan {
42
GetPcSpBp(void * context,uptr * pc,uptr * sp,uptr * bp)43 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
44 ucontext_t *ucontext = (ucontext_t*)context;
45 # if SANITIZER_WORDSIZE == 64
46 *pc = ucontext->uc_mcontext->__ss.__rip;
47 *bp = ucontext->uc_mcontext->__ss.__rbp;
48 *sp = ucontext->uc_mcontext->__ss.__rsp;
49 # else
50 *pc = ucontext->uc_mcontext->__ss.__eip;
51 *bp = ucontext->uc_mcontext->__ss.__ebp;
52 *sp = ucontext->uc_mcontext->__ss.__esp;
53 # endif // SANITIZER_WORDSIZE
54 }
55
56
PlatformHasDifferentMemcpyAndMemmove()57 bool PlatformHasDifferentMemcpyAndMemmove() {
58 // On OS X 10.7 memcpy() and memmove() are both resolved
59 // into memmove$VARIANT$sse42.
60 // See also http://code.google.com/p/address-sanitizer/issues/detail?id=34.
61 // TODO(glider): need to check dynamically that memcpy() and memmove() are
62 // actually the same function.
63 return GetMacosVersion() == MACOS_VERSION_SNOW_LEOPARD;
64 }
65
66 extern "C"
67 void __asan_init();
68
69 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES";
70 LowLevelAllocator allocator_for_env;
71
72 // Change the value of the env var |name|, leaking the original value.
73 // If |name_value| is NULL, the variable is deleted from the environment,
74 // otherwise the corresponding "NAME=value" string is replaced with
75 // |name_value|.
LeakyResetEnv(const char * name,const char * name_value)76 void LeakyResetEnv(const char *name, const char *name_value) {
77 char ***env_ptr = _NSGetEnviron();
78 CHECK(env_ptr);
79 char **environ = *env_ptr;
80 CHECK(environ);
81 uptr name_len = internal_strlen(name);
82 while (*environ != 0) {
83 uptr len = internal_strlen(*environ);
84 if (len > name_len) {
85 const char *p = *environ;
86 if (!internal_memcmp(p, name, name_len) && p[name_len] == '=') {
87 // Match.
88 if (name_value) {
89 // Replace the old value with the new one.
90 *environ = const_cast<char*>(name_value);
91 } else {
92 // Shift the subsequent pointers back.
93 char **del = environ;
94 do {
95 del[0] = del[1];
96 } while (*del++);
97 }
98 }
99 }
100 environ++;
101 }
102 }
103
MaybeReexec()104 void MaybeReexec() {
105 if (!flags()->allow_reexec) return;
106 // Make sure the dynamic ASan runtime library is preloaded so that the
107 // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec
108 // ourselves.
109 Dl_info info;
110 CHECK(dladdr((void*)((uptr)__asan_init), &info));
111 char *dyld_insert_libraries =
112 const_cast<char*>(GetEnv(kDyldInsertLibraries));
113 uptr old_env_len = dyld_insert_libraries ?
114 internal_strlen(dyld_insert_libraries) : 0;
115 uptr fname_len = internal_strlen(info.dli_fname);
116 if (!dyld_insert_libraries ||
117 !REAL(strstr)(dyld_insert_libraries, info.dli_fname)) {
118 // DYLD_INSERT_LIBRARIES is not set or does not contain the runtime
119 // library.
120 char program_name[1024];
121 uint32_t buf_size = sizeof(program_name);
122 _NSGetExecutablePath(program_name, &buf_size);
123 char *new_env = const_cast<char*>(info.dli_fname);
124 if (dyld_insert_libraries) {
125 // Append the runtime dylib name to the existing value of
126 // DYLD_INSERT_LIBRARIES.
127 new_env = (char*)allocator_for_env.Allocate(old_env_len + fname_len + 2);
128 internal_strncpy(new_env, dyld_insert_libraries, old_env_len);
129 new_env[old_env_len] = ':';
130 // Copy fname_len and add a trailing zero.
131 internal_strncpy(new_env + old_env_len + 1, info.dli_fname,
132 fname_len + 1);
133 // Ok to use setenv() since the wrappers don't depend on the value of
134 // asan_inited.
135 setenv(kDyldInsertLibraries, new_env, /*overwrite*/1);
136 } else {
137 // Set DYLD_INSERT_LIBRARIES equal to the runtime dylib name.
138 setenv(kDyldInsertLibraries, info.dli_fname, /*overwrite*/0);
139 }
140 VReport(1, "exec()-ing the program with\n");
141 VReport(1, "%s=%s\n", kDyldInsertLibraries, new_env);
142 VReport(1, "to enable ASan wrappers.\n");
143 VReport(1, "Set ASAN_OPTIONS=allow_reexec=0 to disable this.\n");
144 execv(program_name, *_NSGetArgv());
145 } else {
146 // DYLD_INSERT_LIBRARIES is set and contains the runtime library.
147 if (old_env_len == fname_len) {
148 // It's just the runtime library name - fine to unset the variable.
149 LeakyResetEnv(kDyldInsertLibraries, NULL);
150 } else {
151 uptr env_name_len = internal_strlen(kDyldInsertLibraries);
152 // Allocate memory to hold the previous env var name, its value, the '='
153 // sign and the '\0' char.
154 char *new_env = (char*)allocator_for_env.Allocate(
155 old_env_len + 2 + env_name_len);
156 CHECK(new_env);
157 internal_memset(new_env, '\0', old_env_len + 2 + env_name_len);
158 internal_strncpy(new_env, kDyldInsertLibraries, env_name_len);
159 new_env[env_name_len] = '=';
160 char *new_env_pos = new_env + env_name_len + 1;
161
162 // Iterate over colon-separated pieces of |dyld_insert_libraries|.
163 char *piece_start = dyld_insert_libraries;
164 char *piece_end = NULL;
165 char *old_env_end = dyld_insert_libraries + old_env_len;
166 do {
167 if (piece_start[0] == ':') piece_start++;
168 piece_end = REAL(strchr)(piece_start, ':');
169 if (!piece_end) piece_end = dyld_insert_libraries + old_env_len;
170 if ((uptr)(piece_start - dyld_insert_libraries) > old_env_len) break;
171 uptr piece_len = piece_end - piece_start;
172
173 // If the current piece isn't the runtime library name,
174 // append it to new_env.
175 if ((piece_len != fname_len) ||
176 (internal_strncmp(piece_start, info.dli_fname, fname_len) != 0)) {
177 if (new_env_pos != new_env + env_name_len + 1) {
178 new_env_pos[0] = ':';
179 new_env_pos++;
180 }
181 internal_strncpy(new_env_pos, piece_start, piece_len);
182 }
183 // Move on to the next piece.
184 new_env_pos += piece_len;
185 piece_start = piece_end;
186 } while (piece_start < old_env_end);
187
188 // Can't use setenv() here, because it requires the allocator to be
189 // initialized.
190 // FIXME: instead of filtering DYLD_INSERT_LIBRARIES here, do it in
191 // a separate function called after InitializeAllocator().
192 LeakyResetEnv(kDyldInsertLibraries, new_env);
193 }
194 }
195 }
196
197 // No-op. Mac does not support static linkage anyway.
AsanDoesNotSupportStaticLinkage()198 void *AsanDoesNotSupportStaticLinkage() {
199 return 0;
200 }
201
202 // No-op. Mac does not support static linkage anyway.
AsanCheckDynamicRTPrereqs()203 void AsanCheckDynamicRTPrereqs() {}
204
205 // No-op. Mac does not support static linkage anyway.
AsanCheckIncompatibleRT()206 void AsanCheckIncompatibleRT() {}
207
AsanInterceptsSignal(int signum)208 bool AsanInterceptsSignal(int signum) {
209 return (signum == SIGSEGV || signum == SIGBUS) &&
210 common_flags()->handle_segv;
211 }
212
AsanPlatformThreadInit()213 void AsanPlatformThreadInit() {
214 }
215
ReadContextStack(void * context,uptr * stack,uptr * ssize)216 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
217 UNIMPLEMENTED();
218 }
219
220 // Support for the following functions from libdispatch on Mac OS:
221 // dispatch_async_f()
222 // dispatch_async()
223 // dispatch_sync_f()
224 // dispatch_sync()
225 // dispatch_after_f()
226 // dispatch_after()
227 // dispatch_group_async_f()
228 // dispatch_group_async()
229 // TODO(glider): libdispatch API contains other functions that we don't support
230 // yet.
231 //
232 // dispatch_sync() and dispatch_sync_f() are synchronous, although chances are
233 // they can cause jobs to run on a thread different from the current one.
234 // TODO(glider): if so, we need a test for this (otherwise we should remove
235 // them).
236 //
237 // The following functions use dispatch_barrier_async_f() (which isn't a library
238 // function but is exported) and are thus supported:
239 // dispatch_source_set_cancel_handler_f()
240 // dispatch_source_set_cancel_handler()
241 // dispatch_source_set_event_handler_f()
242 // dispatch_source_set_event_handler()
243 //
244 // The reference manual for Grand Central Dispatch is available at
245 // http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html
246 // The implementation details are at
247 // http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c
248
249 typedef void* dispatch_group_t;
250 typedef void* dispatch_queue_t;
251 typedef void* dispatch_source_t;
252 typedef u64 dispatch_time_t;
253 typedef void (*dispatch_function_t)(void *block);
254 typedef void* (*worker_t)(void *block);
255
256 // A wrapper for the ObjC blocks used to support libdispatch.
257 typedef struct {
258 void *block;
259 dispatch_function_t func;
260 u32 parent_tid;
261 } asan_block_context_t;
262
263 ALWAYS_INLINE
asan_register_worker_thread(int parent_tid,StackTrace * stack)264 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
265 AsanThread *t = GetCurrentThread();
266 if (!t) {
267 t = AsanThread::Create(0, 0);
268 CreateThreadContextArgs args = { t, stack };
269 asanThreadRegistry().CreateThread(*(uptr*)t, true, parent_tid, &args);
270 t->Init();
271 asanThreadRegistry().StartThread(t->tid(), 0, 0);
272 SetCurrentThread(t);
273 }
274 }
275
276 // For use by only those functions that allocated the context via
277 // alloc_asan_context().
278 extern "C"
asan_dispatch_call_block_and_release(void * block)279 void asan_dispatch_call_block_and_release(void *block) {
280 GET_STACK_TRACE_THREAD;
281 asan_block_context_t *context = (asan_block_context_t*)block;
282 VReport(2,
283 "asan_dispatch_call_block_and_release(): "
284 "context: %p, pthread_self: %p\n",
285 block, pthread_self());
286 asan_register_worker_thread(context->parent_tid, &stack);
287 // Call the original dispatcher for the block.
288 context->func(context->block);
289 asan_free(context, &stack, FROM_MALLOC);
290 }
291
292 } // namespace __asan
293
294 using namespace __asan; // NOLINT
295
296 // Wrap |ctxt| and |func| into an asan_block_context_t.
297 // The caller retains control of the allocated context.
298 extern "C"
alloc_asan_context(void * ctxt,dispatch_function_t func,StackTrace * stack)299 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
300 StackTrace *stack) {
301 asan_block_context_t *asan_ctxt =
302 (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
303 asan_ctxt->block = ctxt;
304 asan_ctxt->func = func;
305 asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
306 return asan_ctxt;
307 }
308
309 // Define interceptor for dispatch_*_f function with the three most common
310 // parameters: dispatch_queue_t, context, dispatch_function_t.
311 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f) \
312 INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt, \
313 dispatch_function_t func) { \
314 GET_STACK_TRACE_THREAD; \
315 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
316 if (common_flags()->verbosity >= 2) { \
317 Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n", \
318 asan_ctxt, pthread_self()); \
319 PRINT_CURRENT_STACK(); \
320 } \
321 return REAL(dispatch_x_f)(dq, (void*)asan_ctxt, \
322 asan_dispatch_call_block_and_release); \
323 }
324
325 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)326 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
327 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
328
329 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
330 dispatch_queue_t dq, void *ctxt,
331 dispatch_function_t func) {
332 GET_STACK_TRACE_THREAD;
333 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
334 if (common_flags()->verbosity >= 2) {
335 Report("dispatch_after_f: %p\n", asan_ctxt);
336 PRINT_CURRENT_STACK();
337 }
338 return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
339 asan_dispatch_call_block_and_release);
340 }
341
INTERCEPTOR(void,dispatch_group_async_f,dispatch_group_t group,dispatch_queue_t dq,void * ctxt,dispatch_function_t func)342 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
343 dispatch_queue_t dq, void *ctxt,
344 dispatch_function_t func) {
345 GET_STACK_TRACE_THREAD;
346 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
347 if (common_flags()->verbosity >= 2) {
348 Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n",
349 asan_ctxt, pthread_self());
350 PRINT_CURRENT_STACK();
351 }
352 REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
353 asan_dispatch_call_block_and_release);
354 }
355
356 #if !defined(MISSING_BLOCKS_SUPPORT)
357 extern "C" {
358 void dispatch_async(dispatch_queue_t dq, void(^work)(void));
359 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
360 void(^work)(void));
361 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
362 void(^work)(void));
363 void dispatch_source_set_cancel_handler(dispatch_source_t ds,
364 void(^work)(void));
365 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
366 }
367
368 #define GET_ASAN_BLOCK(work) \
369 void (^asan_block)(void); \
370 int parent_tid = GetCurrentTidOrInvalid(); \
371 asan_block = ^(void) { \
372 GET_STACK_TRACE_THREAD; \
373 asan_register_worker_thread(parent_tid, &stack); \
374 work(); \
375 }
376
377 // Forces the compiler to generate a frame pointer in the function.
378 #define ENABLE_FRAME_POINTER \
379 do { \
380 volatile uptr enable_fp; \
381 enable_fp = GET_CURRENT_FRAME(); \
382 } while (0)
383
384 INTERCEPTOR(void, dispatch_async,
385 dispatch_queue_t dq, void(^work)(void)) {
386 ENABLE_FRAME_POINTER;
387 GET_ASAN_BLOCK(work);
388 REAL(dispatch_async)(dq, asan_block);
389 }
390
391 INTERCEPTOR(void, dispatch_group_async,
392 dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
393 ENABLE_FRAME_POINTER;
394 GET_ASAN_BLOCK(work);
395 REAL(dispatch_group_async)(dg, dq, asan_block);
396 }
397
398 INTERCEPTOR(void, dispatch_after,
399 dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
400 ENABLE_FRAME_POINTER;
401 GET_ASAN_BLOCK(work);
402 REAL(dispatch_after)(when, queue, asan_block);
403 }
404
405 INTERCEPTOR(void, dispatch_source_set_cancel_handler,
406 dispatch_source_t ds, void(^work)(void)) {
407 ENABLE_FRAME_POINTER;
408 GET_ASAN_BLOCK(work);
409 REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
410 }
411
412 INTERCEPTOR(void, dispatch_source_set_event_handler,
413 dispatch_source_t ds, void(^work)(void)) {
414 ENABLE_FRAME_POINTER;
415 GET_ASAN_BLOCK(work);
416 REAL(dispatch_source_set_event_handler)(ds, asan_block);
417 }
418 #endif
419
420 #endif // SANITIZER_MAC
421