contrib/compiler-rt/lib/asan/asan_mac.cc

   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 #if !SANITIZER_IOS
  28 #include <crt_externs.h>  // for _NSGetArgv and _NSGetEnviron
  29 #else
  30 extern "C" {
  31   extern char ***_NSGetArgv(void);
  32 }
  33 #endif
  34
  35 #include <dlfcn.h>  // for dladdr()
  36 #include <mach-o/dyld.h>
  37 #include <mach-o/loader.h>
  38 #include <sys/mman.h>
  39 #include <sys/resource.h>
  40 #include <sys/sysctl.h>
  41 #include <sys/ucontext.h>
  42 #include <fcntl.h>
  43 #include <pthread.h>
  44 #include <stdlib.h>  // for free()
  45 #include <unistd.h>
  46 #include <libkern/OSAtomic.h>
  47
  48 namespace __asan {
  49
  50 void InitializePlatformInterceptors() {}
  51
  52 bool PlatformHasDifferentMemcpyAndMemmove() {
  53   // On OS X 10.7 memcpy() and memmove() are both resolved
  54   // into memmove$VARIANT$sse42.
  55   // See also http://code.google.com/p/address-sanitizer/issues/detail?id=34.
  56   // TODO(glider): need to check dynamically that memcpy() and memmove() are
  57   // actually the same function.
  58   return GetMacosVersion() == MACOS_VERSION_SNOW_LEOPARD;
  59 }
  60
  61 extern "C"
  62 void __asan_init();
  63
  64 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES";
  65 LowLevelAllocator allocator_for_env;
  66
  67 // Change the value of the env var |name|, leaking the original value.
  68 // If |name_value| is NULL, the variable is deleted from the environment,
  69 // otherwise the corresponding "NAME=value" string is replaced with
  70 // |name_value|.
  71 void LeakyResetEnv(const char *name, const char *name_value) {
  72   char **env = GetEnviron();
  73   uptr name_len = internal_strlen(name);
  74   while (*env != 0) {
  75     uptr len = internal_strlen(*env);
  76     if (len > name_len) {
  77       const char *p = *env;
  78       if (!internal_memcmp(p, name, name_len) && p[name_len] == '=') {
  79         // Match.
  80         if (name_value) {
  81           // Replace the old value with the new one.
  82           *env = const_cast<char*>(name_value);
  83         } else {
  84           // Shift the subsequent pointers back.
  85           char **del = env;
  86           do {
  87             del[0] = del[1];
  88           } while (*del++);
  89         }
  90       }
  91     }
  92     env++;
  93   }
  94 }
  95
  96 static bool reexec_disabled = false;
  97
  98 void DisableReexec() {
  99   reexec_disabled = true;
 100 }
 101
 102 bool DyldNeedsEnvVariable() {
 103 // If running on OS X 10.11+ or iOS 9.0+, dyld will interpose even if
 104 // DYLD_INSERT_LIBRARIES is not set.
 105
 106 #if SANITIZER_IOSSIM
 107   // GetMacosVersion will not work for the simulator, whose kernel version
 108   // is tied to the host. Use a weak linking hack for the simulator.
 109   // This API was introduced in the same version of the OS as the dyld
 110   // optimization.
 111
 112   // Check for presence of a symbol that is available on OS X 10.11+, iOS 9.0+.
 113   return (dlsym(RTLD_NEXT, "mach_memory_info") == nullptr);
 114 #else
 115   return (GetMacosVersion() <= MACOS_VERSION_YOSEMITE);
 116 #endif
 117 }
 118
 119 void MaybeReexec() {
 120   if (reexec_disabled) return;
 121
 122   // Make sure the dynamic ASan runtime library is preloaded so that the
 123   // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec
 124   // ourselves.
 125   Dl_info info;
 126   CHECK(dladdr((void*)((uptr)__asan_init), &info));
 127   char *dyld_insert_libraries =
 128       const_cast<char*>(GetEnv(kDyldInsertLibraries));
 129   uptr old_env_len = dyld_insert_libraries ?
 130       internal_strlen(dyld_insert_libraries) : 0;
 131   uptr fname_len = internal_strlen(info.dli_fname);
 132   const char *dylib_name = StripModuleName(info.dli_fname);
 133   uptr dylib_name_len = internal_strlen(dylib_name);
 134
 135   bool lib_is_in_env =
 136       dyld_insert_libraries && REAL(strstr)(dyld_insert_libraries, dylib_name);
 137   if (DyldNeedsEnvVariable() && !lib_is_in_env) {
 138     // DYLD_INSERT_LIBRARIES is not set or does not contain the runtime
 139     // library.
 140     char program_name[1024];
 141     uint32_t buf_size = sizeof(program_name);
 142     _NSGetExecutablePath(program_name, &buf_size);
 143     char *new_env = const_cast<char*>(info.dli_fname);
 144     if (dyld_insert_libraries) {
 145       // Append the runtime dylib name to the existing value of
 146       // DYLD_INSERT_LIBRARIES.
 147       new_env = (char*)allocator_for_env.Allocate(old_env_len + fname_len + 2);
 148       internal_strncpy(new_env, dyld_insert_libraries, old_env_len);
 149       new_env[old_env_len] = ':';
 150       // Copy fname_len and add a trailing zero.
 151       internal_strncpy(new_env + old_env_len + 1, info.dli_fname,
 152                        fname_len + 1);
 153       // Ok to use setenv() since the wrappers don't depend on the value of
 154       // asan_inited.
 155       setenv(kDyldInsertLibraries, new_env, /*overwrite*/1);
 156     } else {
 157       // Set DYLD_INSERT_LIBRARIES equal to the runtime dylib name.
 158       setenv(kDyldInsertLibraries, info.dli_fname, /*overwrite*/0);
 159     }
 160     VReport(1, "exec()-ing the program with\n");
 161     VReport(1, "%s=%s\n", kDyldInsertLibraries, new_env);
 162     VReport(1, "to enable ASan wrappers.\n");
 163     execv(program_name, *_NSGetArgv());
 164
 165     // We get here only if execv() failed.
 166     Report("ERROR: The process is launched without DYLD_INSERT_LIBRARIES, "
 167            "which is required for ASan to work. ASan tried to set the "
 168            "environment variable and re-execute itself, but execv() failed, "
 169            "possibly because of sandbox restrictions. Make sure to launch the "
 170            "executable with:\n%s=%s\n", kDyldInsertLibraries, new_env);
 171     CHECK("execv failed" && 0);
 172   }
 173
 174   if (!lib_is_in_env)
 175     return;
 176
 177   // DYLD_INSERT_LIBRARIES is set and contains the runtime library. Let's remove
 178   // the dylib from the environment variable, because interceptors are installed
 179   // and we don't want our children to inherit the variable.
 180
 181   uptr env_name_len = internal_strlen(kDyldInsertLibraries);
 182   // Allocate memory to hold the previous env var name, its value, the '='
 183   // sign and the '\0' char.
 184   char *new_env = (char*)allocator_for_env.Allocate(
 185       old_env_len + 2 + env_name_len);
 186   CHECK(new_env);
 187   internal_memset(new_env, '\0', old_env_len + 2 + env_name_len);
 188   internal_strncpy(new_env, kDyldInsertLibraries, env_name_len);
 189   new_env[env_name_len] = '=';
 190   char *new_env_pos = new_env + env_name_len + 1;
 191
 192   // Iterate over colon-separated pieces of |dyld_insert_libraries|.
 193   char *piece_start = dyld_insert_libraries;
 194   char *piece_end = NULL;
 195   char *old_env_end = dyld_insert_libraries + old_env_len;
 196   do {
 197     if (piece_start[0] == ':') piece_start++;
 198     piece_end = REAL(strchr)(piece_start, ':');
 199     if (!piece_end) piece_end = dyld_insert_libraries + old_env_len;
 200     if ((uptr)(piece_start - dyld_insert_libraries) > old_env_len) break;
 201     uptr piece_len = piece_end - piece_start;
 202
 203     char *filename_start =
 204         (char *)internal_memrchr(piece_start, '/', piece_len);
 205     uptr filename_len = piece_len;
 206     if (filename_start) {
 207       filename_start += 1;
 208       filename_len = piece_len - (filename_start - piece_start);
 209     } else {
 210       filename_start = piece_start;
 211     }
 212
 213     // If the current piece isn't the runtime library name,
 214     // append it to new_env.
 215     if ((dylib_name_len != filename_len) ||
 216         (internal_memcmp(filename_start, dylib_name, dylib_name_len) != 0)) {
 217       if (new_env_pos != new_env + env_name_len + 1) {
 218         new_env_pos[0] = ':';
 219         new_env_pos++;
 220       }
 221       internal_strncpy(new_env_pos, piece_start, piece_len);
 222       new_env_pos += piece_len;
 223     }
 224     // Move on to the next piece.
 225     piece_start = piece_end;
 226   } while (piece_start < old_env_end);
 227
 228   // Can't use setenv() here, because it requires the allocator to be
 229   // initialized.
 230   // FIXME: instead of filtering DYLD_INSERT_LIBRARIES here, do it in
 231   // a separate function called after InitializeAllocator().
 232   if (new_env_pos == new_env + env_name_len + 1) new_env = NULL;
 233   LeakyResetEnv(kDyldInsertLibraries, new_env);
 234 }
 235
 236 // No-op. Mac does not support static linkage anyway.
 237 void *AsanDoesNotSupportStaticLinkage() {
 238   return 0;
 239 }
 240
 241 // No-op. Mac does not support static linkage anyway.
 242 void AsanCheckDynamicRTPrereqs() {}
 243
 244 // No-op. Mac does not support static linkage anyway.
 245 void AsanCheckIncompatibleRT() {}
 246
 247 void AsanPlatformThreadInit() {
 248 }
 249
 250 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
 251   UNIMPLEMENTED();
 252 }
 253
 254 // Support for the following functions from libdispatch on Mac OS:
 255 //   dispatch_async_f()
 256 //   dispatch_async()
 257 //   dispatch_sync_f()
 258 //   dispatch_sync()
 259 //   dispatch_after_f()
 260 //   dispatch_after()
 261 //   dispatch_group_async_f()
 262 //   dispatch_group_async()
 263 // TODO(glider): libdispatch API contains other functions that we don't support
 264 // yet.
 265 //
 266 // dispatch_sync() and dispatch_sync_f() are synchronous, although chances are
 267 // they can cause jobs to run on a thread different from the current one.
 268 // TODO(glider): if so, we need a test for this (otherwise we should remove
 269 // them).
 270 //
 271 // The following functions use dispatch_barrier_async_f() (which isn't a library
 272 // function but is exported) and are thus supported:
 273 //   dispatch_source_set_cancel_handler_f()
 274 //   dispatch_source_set_cancel_handler()
 275 //   dispatch_source_set_event_handler_f()
 276 //   dispatch_source_set_event_handler()
 277 //
 278 // The reference manual for Grand Central Dispatch is available at
 279 //   http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html
 280 // The implementation details are at
 281 //   http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c
 282
 283 typedef void* dispatch_group_t;
 284 typedef void* dispatch_queue_t;
 285 typedef void* dispatch_source_t;
 286 typedef u64 dispatch_time_t;
 287 typedef void (*dispatch_function_t)(void *block);
 288 typedef void* (*worker_t)(void *block);
 289
 290 // A wrapper for the ObjC blocks used to support libdispatch.
 291 typedef struct {
 292   void *block;
 293   dispatch_function_t func;
 294   u32 parent_tid;
 295 } asan_block_context_t;
 296
 297 ALWAYS_INLINE
 298 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
 299   AsanThread *t = GetCurrentThread();
 300   if (!t) {
 301     t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr,
 302                            parent_tid, stack, /* detached */ true);
 303     t->Init();
 304     asanThreadRegistry().StartThread(t->tid(), 0, 0);
 305     SetCurrentThread(t);
 306   }
 307 }
 308
 309 // For use by only those functions that allocated the context via
 310 // alloc_asan_context().
 311 extern "C"
 312 void asan_dispatch_call_block_and_release(void *block) {
 313   GET_STACK_TRACE_THREAD;
 314   asan_block_context_t *context = (asan_block_context_t*)block;
 315   VReport(2,
 316           "asan_dispatch_call_block_and_release(): "
 317           "context: %p, pthread_self: %p\n",
 318           block, pthread_self());
 319   asan_register_worker_thread(context->parent_tid, &stack);
 320   // Call the original dispatcher for the block.
 321   context->func(context->block);
 322   asan_free(context, &stack, FROM_MALLOC);
 323 }
 324
 325 }  // namespace __asan
 326
 327 using namespace __asan;  // NOLINT
 328
 329 // Wrap |ctxt| and |func| into an asan_block_context_t.
 330 // The caller retains control of the allocated context.
 331 extern "C"
 332 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
 333                                          BufferedStackTrace *stack) {
 334   asan_block_context_t *asan_ctxt =
 335       (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
 336   asan_ctxt->block = ctxt;
 337   asan_ctxt->func = func;
 338   asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
 339   return asan_ctxt;
 340 }
 341
 342 // Define interceptor for dispatch_*_f function with the three most common
 343 // parameters: dispatch_queue_t, context, dispatch_function_t.
 344 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f)                                \
 345   INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt,            \
 346                                   dispatch_function_t func) {                 \
 347     GET_STACK_TRACE_THREAD;                                                   \
 348     asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
 349     if (Verbosity() >= 2) {                                     \
 350       Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n",             \
 351              asan_ctxt, pthread_self());                                      \
 352       PRINT_CURRENT_STACK();                                                  \
 353     }                                                                         \
 354     return REAL(dispatch_x_f)(dq, (void*)asan_ctxt,                           \
 355                               asan_dispatch_call_block_and_release);          \
 356   }
 357
 358 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
 359 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
 360 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
 361
 362 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
 363                                     dispatch_queue_t dq, void *ctxt,
 364                                     dispatch_function_t func) {
 365   GET_STACK_TRACE_THREAD;
 366   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 367   if (Verbosity() >= 2) {
 368     Report("dispatch_after_f: %p\n", asan_ctxt);
 369     PRINT_CURRENT_STACK();
 370   }
 371   return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
 372                                 asan_dispatch_call_block_and_release);
 373 }
 374
 375 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
 376                                           dispatch_queue_t dq, void *ctxt,
 377                                           dispatch_function_t func) {
 378   GET_STACK_TRACE_THREAD;
 379   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 380   if (Verbosity() >= 2) {
 381     Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n",
 382            asan_ctxt, pthread_self());
 383     PRINT_CURRENT_STACK();
 384   }
 385   REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
 386                                asan_dispatch_call_block_and_release);
 387 }
 388
 389 #if !defined(MISSING_BLOCKS_SUPPORT)
 390 extern "C" {
 391 void dispatch_async(dispatch_queue_t dq, void(^work)(void));
 392 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
 393                           void(^work)(void));
 394 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
 395                     void(^work)(void));
 396 void dispatch_source_set_cancel_handler(dispatch_source_t ds,
 397                                         void(^work)(void));
 398 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
 399 }
 400
 401 #define GET_ASAN_BLOCK(work) \
 402   void (^asan_block)(void);  \
 403   int parent_tid = GetCurrentTidOrInvalid(); \
 404   asan_block = ^(void) { \
 405     GET_STACK_TRACE_THREAD; \
 406     asan_register_worker_thread(parent_tid, &stack); \
 407     work(); \
 408   }
 409
 410 INTERCEPTOR(void, dispatch_async,
 411             dispatch_queue_t dq, void(^work)(void)) {
 412   ENABLE_FRAME_POINTER;
 413   GET_ASAN_BLOCK(work);
 414   REAL(dispatch_async)(dq, asan_block);
 415 }
 416
 417 INTERCEPTOR(void, dispatch_group_async,
 418             dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
 419   ENABLE_FRAME_POINTER;
 420   GET_ASAN_BLOCK(work);
 421   REAL(dispatch_group_async)(dg, dq, asan_block);
 422 }
 423
 424 INTERCEPTOR(void, dispatch_after,
 425             dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
 426   ENABLE_FRAME_POINTER;
 427   GET_ASAN_BLOCK(work);
 428   REAL(dispatch_after)(when, queue, asan_block);
 429 }
 430
 431 INTERCEPTOR(void, dispatch_source_set_cancel_handler,
 432             dispatch_source_t ds, void(^work)(void)) {
 433   if (!work) {
 434     REAL(dispatch_source_set_cancel_handler)(ds, work);
 435     return;
 436   }
 437   ENABLE_FRAME_POINTER;
 438   GET_ASAN_BLOCK(work);
 439   REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
 440 }
 441
 442 INTERCEPTOR(void, dispatch_source_set_event_handler,
 443             dispatch_source_t ds, void(^work)(void)) {
 444   ENABLE_FRAME_POINTER;
 445   GET_ASAN_BLOCK(work);
 446   REAL(dispatch_source_set_event_handler)(ds, asan_block);
 447 }
 448 #endif
 449
 450 #endif  // SANITIZER_MAC