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 43 void InitializePlatformInterceptors() {} 44 45 bool PlatformHasDifferentMemcpyAndMemmove() { 46 // On OS X 10.7 memcpy() and memmove() are both resolved 47 // into memmove$VARIANT$sse42. 48 // See also http://code.google.com/p/address-sanitizer/issues/detail?id=34. 49 // TODO(glider): need to check dynamically that memcpy() and memmove() are 50 // actually the same function. 51 return GetMacosVersion() == MACOS_VERSION_SNOW_LEOPARD; 52 } 53 54 extern "C" 55 void __asan_init(); 56 57 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES"; 58 LowLevelAllocator allocator_for_env; 59 60 // Change the value of the env var |name|, leaking the original value. 61 // If |name_value| is NULL, the variable is deleted from the environment, 62 // otherwise the corresponding "NAME=value" string is replaced with 63 // |name_value|. 64 void LeakyResetEnv(const char *name, const char *name_value) { 65 char ***env_ptr = _NSGetEnviron(); 66 CHECK(env_ptr); 67 char **environ = *env_ptr; 68 CHECK(environ); 69 uptr name_len = internal_strlen(name); 70 while (*environ != 0) { 71 uptr len = internal_strlen(*environ); 72 if (len > name_len) { 73 const char *p = *environ; 74 if (!internal_memcmp(p, name, name_len) && p[name_len] == '=') { 75 // Match. 76 if (name_value) { 77 // Replace the old value with the new one. 78 *environ = const_cast<char*>(name_value); 79 } else { 80 // Shift the subsequent pointers back. 81 char **del = environ; 82 do { 83 del[0] = del[1]; 84 } while (*del++); 85 } 86 } 87 } 88 environ++; 89 } 90 } 91 92 static bool reexec_disabled = false; 93 94 void DisableReexec() { 95 reexec_disabled = true; 96 } 97 98 void MaybeReexec() { 99 if (reexec_disabled) return; 100 101 // Make sure the dynamic ASan runtime library is preloaded so that the 102 // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec 103 // ourselves. 104 Dl_info info; 105 CHECK(dladdr((void*)((uptr)__asan_init), &info)); 106 char *dyld_insert_libraries = 107 const_cast<char*>(GetEnv(kDyldInsertLibraries)); 108 uptr old_env_len = dyld_insert_libraries ? 109 internal_strlen(dyld_insert_libraries) : 0; 110 uptr fname_len = internal_strlen(info.dli_fname); 111 const char *dylib_name = StripModuleName(info.dli_fname); 112 uptr dylib_name_len = internal_strlen(dylib_name); 113 if (!dyld_insert_libraries || 114 !REAL(strstr)(dyld_insert_libraries, dylib_name)) { 115 // DYLD_INSERT_LIBRARIES is not set or does not contain the runtime 116 // library. 117 char program_name[1024]; 118 uint32_t buf_size = sizeof(program_name); 119 _NSGetExecutablePath(program_name, &buf_size); 120 char *new_env = const_cast<char*>(info.dli_fname); 121 if (dyld_insert_libraries) { 122 // Append the runtime dylib name to the existing value of 123 // DYLD_INSERT_LIBRARIES. 124 new_env = (char*)allocator_for_env.Allocate(old_env_len + fname_len + 2); 125 internal_strncpy(new_env, dyld_insert_libraries, old_env_len); 126 new_env[old_env_len] = ':'; 127 // Copy fname_len and add a trailing zero. 128 internal_strncpy(new_env + old_env_len + 1, info.dli_fname, 129 fname_len + 1); 130 // Ok to use setenv() since the wrappers don't depend on the value of 131 // asan_inited. 132 setenv(kDyldInsertLibraries, new_env, /*overwrite*/1); 133 } else { 134 // Set DYLD_INSERT_LIBRARIES equal to the runtime dylib name. 135 setenv(kDyldInsertLibraries, info.dli_fname, /*overwrite*/0); 136 } 137 VReport(1, "exec()-ing the program with\n"); 138 VReport(1, "%s=%s\n", kDyldInsertLibraries, new_env); 139 VReport(1, "to enable ASan wrappers.\n"); 140 execv(program_name, *_NSGetArgv()); 141 142 // We get here only if execv() failed. 143 Report("ERROR: The process is launched without DYLD_INSERT_LIBRARIES, " 144 "which is required for ASan to work. ASan tried to set the " 145 "environment variable and re-execute itself, but execv() failed, " 146 "possibly because of sandbox restrictions. Make sure to launch the " 147 "executable with:\n%s=%s\n", kDyldInsertLibraries, new_env); 148 CHECK("execv failed" && 0); 149 } 150 151 // DYLD_INSERT_LIBRARIES is set and contains the runtime library. Let's remove 152 // the dylib from the environment variable, because interceptors are installed 153 // and we don't want our children to inherit the variable. 154 155 uptr env_name_len = internal_strlen(kDyldInsertLibraries); 156 // Allocate memory to hold the previous env var name, its value, the '=' 157 // sign and the '\0' char. 158 char *new_env = (char*)allocator_for_env.Allocate( 159 old_env_len + 2 + env_name_len); 160 CHECK(new_env); 161 internal_memset(new_env, '\0', old_env_len + 2 + env_name_len); 162 internal_strncpy(new_env, kDyldInsertLibraries, env_name_len); 163 new_env[env_name_len] = '='; 164 char *new_env_pos = new_env + env_name_len + 1; 165 166 // Iterate over colon-separated pieces of |dyld_insert_libraries|. 167 char *piece_start = dyld_insert_libraries; 168 char *piece_end = NULL; 169 char *old_env_end = dyld_insert_libraries + old_env_len; 170 do { 171 if (piece_start[0] == ':') piece_start++; 172 piece_end = REAL(strchr)(piece_start, ':'); 173 if (!piece_end) piece_end = dyld_insert_libraries + old_env_len; 174 if ((uptr)(piece_start - dyld_insert_libraries) > old_env_len) break; 175 uptr piece_len = piece_end - piece_start; 176 177 char *filename_start = 178 (char *)internal_memrchr(piece_start, '/', piece_len); 179 uptr filename_len = piece_len; 180 if (filename_start) { 181 filename_start += 1; 182 filename_len = piece_len - (filename_start - piece_start); 183 } else { 184 filename_start = piece_start; 185 } 186 187 // If the current piece isn't the runtime library name, 188 // append it to new_env. 189 if ((dylib_name_len != filename_len) || 190 (internal_memcmp(filename_start, dylib_name, dylib_name_len) != 0)) { 191 if (new_env_pos != new_env + env_name_len + 1) { 192 new_env_pos[0] = ':'; 193 new_env_pos++; 194 } 195 internal_strncpy(new_env_pos, piece_start, piece_len); 196 new_env_pos += piece_len; 197 } 198 // Move on to the next piece. 199 piece_start = piece_end; 200 } while (piece_start < old_env_end); 201 202 // Can't use setenv() here, because it requires the allocator to be 203 // initialized. 204 // FIXME: instead of filtering DYLD_INSERT_LIBRARIES here, do it in 205 // a separate function called after InitializeAllocator(). 206 if (new_env_pos == new_env + env_name_len + 1) new_env = NULL; 207 LeakyResetEnv(kDyldInsertLibraries, new_env); 208 } 209 210 // No-op. Mac does not support static linkage anyway. 211 void *AsanDoesNotSupportStaticLinkage() { 212 return 0; 213 } 214 215 // No-op. Mac does not support static linkage anyway. 216 void AsanCheckDynamicRTPrereqs() {} 217 218 // No-op. Mac does not support static linkage anyway. 219 void AsanCheckIncompatibleRT() {} 220 221 void AsanPlatformThreadInit() { 222 } 223 224 void ReadContextStack(void *context, uptr *stack, uptr *ssize) { 225 UNIMPLEMENTED(); 226 } 227 228 // Support for the following functions from libdispatch on Mac OS: 229 // dispatch_async_f() 230 // dispatch_async() 231 // dispatch_sync_f() 232 // dispatch_sync() 233 // dispatch_after_f() 234 // dispatch_after() 235 // dispatch_group_async_f() 236 // dispatch_group_async() 237 // TODO(glider): libdispatch API contains other functions that we don't support 238 // yet. 239 // 240 // dispatch_sync() and dispatch_sync_f() are synchronous, although chances are 241 // they can cause jobs to run on a thread different from the current one. 242 // TODO(glider): if so, we need a test for this (otherwise we should remove 243 // them). 244 // 245 // The following functions use dispatch_barrier_async_f() (which isn't a library 246 // function but is exported) and are thus supported: 247 // dispatch_source_set_cancel_handler_f() 248 // dispatch_source_set_cancel_handler() 249 // dispatch_source_set_event_handler_f() 250 // dispatch_source_set_event_handler() 251 // 252 // The reference manual for Grand Central Dispatch is available at 253 // http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html 254 // The implementation details are at 255 // http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c 256 257 typedef void* dispatch_group_t; 258 typedef void* dispatch_queue_t; 259 typedef void* dispatch_source_t; 260 typedef u64 dispatch_time_t; 261 typedef void (*dispatch_function_t)(void *block); 262 typedef void* (*worker_t)(void *block); 263 264 // A wrapper for the ObjC blocks used to support libdispatch. 265 typedef struct { 266 void *block; 267 dispatch_function_t func; 268 u32 parent_tid; 269 } asan_block_context_t; 270 271 ALWAYS_INLINE 272 void asan_register_worker_thread(int parent_tid, StackTrace *stack) { 273 AsanThread *t = GetCurrentThread(); 274 if (!t) { 275 t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr, 276 parent_tid, stack, /* detached */ true); 277 t->Init(); 278 asanThreadRegistry().StartThread(t->tid(), 0, 0); 279 SetCurrentThread(t); 280 } 281 } 282 283 // For use by only those functions that allocated the context via 284 // alloc_asan_context(). 285 extern "C" 286 void asan_dispatch_call_block_and_release(void *block) { 287 GET_STACK_TRACE_THREAD; 288 asan_block_context_t *context = (asan_block_context_t*)block; 289 VReport(2, 290 "asan_dispatch_call_block_and_release(): " 291 "context: %p, pthread_self: %p\n", 292 block, pthread_self()); 293 asan_register_worker_thread(context->parent_tid, &stack); 294 // Call the original dispatcher for the block. 295 context->func(context->block); 296 asan_free(context, &stack, FROM_MALLOC); 297 } 298 299 } // namespace __asan 300 301 using namespace __asan; // NOLINT 302 303 // Wrap |ctxt| and |func| into an asan_block_context_t. 304 // The caller retains control of the allocated context. 305 extern "C" 306 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func, 307 BufferedStackTrace *stack) { 308 asan_block_context_t *asan_ctxt = 309 (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack); 310 asan_ctxt->block = ctxt; 311 asan_ctxt->func = func; 312 asan_ctxt->parent_tid = GetCurrentTidOrInvalid(); 313 return asan_ctxt; 314 } 315 316 // Define interceptor for dispatch_*_f function with the three most common 317 // parameters: dispatch_queue_t, context, dispatch_function_t. 318 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f) \ 319 INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt, \ 320 dispatch_function_t func) { \ 321 GET_STACK_TRACE_THREAD; \ 322 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \ 323 if (Verbosity() >= 2) { \ 324 Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n", \ 325 asan_ctxt, pthread_self()); \ 326 PRINT_CURRENT_STACK(); \ 327 } \ 328 return REAL(dispatch_x_f)(dq, (void*)asan_ctxt, \ 329 asan_dispatch_call_block_and_release); \ 330 } 331 332 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f) 333 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f) 334 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f) 335 336 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when, 337 dispatch_queue_t dq, void *ctxt, 338 dispatch_function_t func) { 339 GET_STACK_TRACE_THREAD; 340 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); 341 if (Verbosity() >= 2) { 342 Report("dispatch_after_f: %p\n", asan_ctxt); 343 PRINT_CURRENT_STACK(); 344 } 345 return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt, 346 asan_dispatch_call_block_and_release); 347 } 348 349 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group, 350 dispatch_queue_t dq, void *ctxt, 351 dispatch_function_t func) { 352 GET_STACK_TRACE_THREAD; 353 asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); 354 if (Verbosity() >= 2) { 355 Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n", 356 asan_ctxt, pthread_self()); 357 PRINT_CURRENT_STACK(); 358 } 359 REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt, 360 asan_dispatch_call_block_and_release); 361 } 362 363 #if !defined(MISSING_BLOCKS_SUPPORT) 364 extern "C" { 365 void dispatch_async(dispatch_queue_t dq, void(^work)(void)); 366 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq, 367 void(^work)(void)); 368 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue, 369 void(^work)(void)); 370 void dispatch_source_set_cancel_handler(dispatch_source_t ds, 371 void(^work)(void)); 372 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void)); 373 } 374 375 #define GET_ASAN_BLOCK(work) \ 376 void (^asan_block)(void); \ 377 int parent_tid = GetCurrentTidOrInvalid(); \ 378 asan_block = ^(void) { \ 379 GET_STACK_TRACE_THREAD; \ 380 asan_register_worker_thread(parent_tid, &stack); \ 381 work(); \ 382 } 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 if (!work) { 408 REAL(dispatch_source_set_cancel_handler)(ds, work); 409 return; 410 } 411 ENABLE_FRAME_POINTER; 412 GET_ASAN_BLOCK(work); 413 REAL(dispatch_source_set_cancel_handler)(ds, asan_block); 414 } 415 416 INTERCEPTOR(void, dispatch_source_set_event_handler, 417 dispatch_source_t ds, void(^work)(void)) { 418 ENABLE_FRAME_POINTER; 419 GET_ASAN_BLOCK(work); 420 REAL(dispatch_source_set_event_handler)(ds, asan_block); 421 } 422 #endif 423 424 #endif // SANITIZER_MAC 425
