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 41namespace __asan { 42 43void InitializePlatformInterceptors() {} 44 45bool 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 54extern "C" 55void __asan_init(); 56 57static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES"; 58LowLevelAllocator 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|. 64void 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 92static bool reexec_disabled = false; 93 94void DisableReexec() { 95 reexec_disabled = true; 96} 97 98void 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. 211void *AsanDoesNotSupportStaticLinkage() { 212 return 0; 213} 214 215// No-op. Mac does not support static linkage anyway. 216void AsanCheckDynamicRTPrereqs() {} 217 218// No-op. Mac does not support static linkage anyway. 219void AsanCheckIncompatibleRT() {} 220 221void AsanPlatformThreadInit() { 222} 223 224void 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 257typedef void* dispatch_group_t; 258typedef void* dispatch_queue_t; 259typedef void* dispatch_source_t; 260typedef u64 dispatch_time_t; 261typedef void (*dispatch_function_t)(void *block); 262typedef void* (*worker_t)(void *block); 263 264// A wrapper for the ObjC blocks used to support libdispatch. 265typedef struct { 266 void *block; 267 dispatch_function_t func; 268 u32 parent_tid; 269} asan_block_context_t; 270 271ALWAYS_INLINE 272void 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(). 285extern "C" 286void 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 301using namespace __asan; // NOLINT 302 303// Wrap |ctxt| and |func| into an asan_block_context_t. 304// The caller retains control of the allocated context. 305extern "C" 306asan_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 332INTERCEPT_DISPATCH_X_F_3(dispatch_async_f) 333INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f) 334INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f) 335 336INTERCEPTOR(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 349INTERCEPTOR(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) 364extern "C" { 365void dispatch_async(dispatch_queue_t dq, void(^work)(void)); 366void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq, 367 void(^work)(void)); 368void dispatch_after(dispatch_time_t when, dispatch_queue_t queue, 369 void(^work)(void)); 370void dispatch_source_set_cancel_handler(dispatch_source_t ds, 371 void(^work)(void)); 372void 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 384INTERCEPTOR(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 391INTERCEPTOR(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 398INTERCEPTOR(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 405INTERCEPTOR(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 416INTERCEPTOR(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