libsanitizer/asan/asan_mac.cc

   1 //===-- asan_mac.cc -------------------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // Mac-specific details.
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_common/sanitizer_platform.h"
  14 #if SANITIZER_MAC
  15
  16 #include "asan_interceptors.h"
  17 #include "asan_internal.h"
  18 #include "asan_mapping.h"
  19 #include "asan_stack.h"
  20 #include "asan_thread.h"
  21 #include "sanitizer_common/sanitizer_atomic.h"
  22 #include "sanitizer_common/sanitizer_libc.h"
  23 #include "sanitizer_common/sanitizer_mac.h"
  24
  25 #if !SANITIZER_IOS
  26 #include <crt_externs.h>  // for _NSGetArgv and _NSGetEnviron
  27 #else
  28 extern "C" {
  29   extern char ***_NSGetArgv(void);
  30 }
  31 #endif
  32
  33 #include <dlfcn.h>  // for dladdr()
  34 #include <fcntl.h>
  35 #include <libkern/OSAtomic.h>
  36 #include <mach-o/dyld.h>
  37 #include <mach-o/loader.h>
  38 #include <pthread.h>
  39 #include <stdlib.h>  // for free()
  40 #include <sys/mman.h>
  41 #include <sys/resource.h>
  42 #include <sys/sysctl.h>
  43 #include <sys/ucontext.h>
  44 #include <unistd.h>
  45
  46 namespace __asan {
  47
  48 void InitializePlatformInterceptors() {}
  49
  50 bool PlatformHasDifferentMemcpyAndMemmove() {
  51   // On OS X 10.7 memcpy() and memmove() are both resolved
  52   // into memmove$VARIANT$sse42.
  53   // See also http://code.google.com/p/address-sanitizer/issues/detail?id=34.
  54   // TODO(glider): need to check dynamically that memcpy() and memmove() are
  55   // actually the same function.
  56   return GetMacosVersion() == MACOS_VERSION_SNOW_LEOPARD;
  57 }
  58
  59 extern "C"
  60 void __asan_init();
  61
  62 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES";
  63 LowLevelAllocator allocator_for_env;
  64
  65 // Change the value of the env var |name|, leaking the original value.
  66 // If |name_value| is NULL, the variable is deleted from the environment,
  67 // otherwise the corresponding "NAME=value" string is replaced with
  68 // |name_value|.
  69 void LeakyResetEnv(const char *name, const char *name_value) {
  70   char **env = GetEnviron();
  71   uptr name_len = internal_strlen(name);
  72   while (*env != 0) {
  73     uptr len = internal_strlen(*env);
  74     if (len > name_len) {
  75       const char *p = *env;
  76       if (!internal_memcmp(p, name, name_len) && p[name_len] == '=') {
  77         // Match.
  78         if (name_value) {
  79           // Replace the old value with the new one.
  80           *env = const_cast<char*>(name_value);
  81         } else {
  82           // Shift the subsequent pointers back.
  83           char **del = env;
  84           do {
  85             del[0] = del[1];
  86           } while (*del++);
  87         }
  88       }
  89     }
  90     env++;
  91   }
  92 }
  93
  94 static bool reexec_disabled = false;
  95
  96 void DisableReexec() {
  97   reexec_disabled = true;
  98 }
  99
 100 extern "C" SANITIZER_WEAK_ATTRIBUTE double dyldVersionNumber;
 101 static const double kMinDyldVersionWithAutoInterposition = 360.0;
 102
 103 bool DyldNeedsEnvVariable() {
 104   // Although sanitizer support was added to LLVM on OS X 10.7+, GCC users
 105   // still may want use them on older systems. On older Darwin platforms, dyld
 106   // doesn't export dyldVersionNumber symbol and we simply return true.
 107   if (!&dyldVersionNumber) return true;
 108   // If running on OS X 10.11+ or iOS 9.0+, dyld will interpose even if
 109   // DYLD_INSERT_LIBRARIES is not set. However, checking OS version via
 110   // GetMacosVersion() doesn't work for the simulator. Let's instead check
 111   // `dyldVersionNumber`, which is exported by dyld, against a known version
 112   // number from the first OS release where this appeared.
 113   return dyldVersionNumber < kMinDyldVersionWithAutoInterposition;
 114 }
 115
 116 void MaybeReexec() {
 117   if (reexec_disabled) return;
 118
 119   // Make sure the dynamic ASan runtime library is preloaded so that the
 120   // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec
 121   // ourselves.
 122   Dl_info info;
 123   CHECK(dladdr((void*)((uptr)__asan_init), &info));
 124   char *dyld_insert_libraries =
 125       const_cast<char*>(GetEnv(kDyldInsertLibraries));
 126   uptr old_env_len = dyld_insert_libraries ?
 127       internal_strlen(dyld_insert_libraries) : 0;
 128   uptr fname_len = internal_strlen(info.dli_fname);
 129   const char *dylib_name = StripModuleName(info.dli_fname);
 130   uptr dylib_name_len = internal_strlen(dylib_name);
 131
 132   bool lib_is_in_env =
 133       dyld_insert_libraries && REAL(strstr)(dyld_insert_libraries, dylib_name);
 134   if (DyldNeedsEnvVariable() && !lib_is_in_env) {
 135     // DYLD_INSERT_LIBRARIES is not set or does not contain the runtime
 136     // library.
 137     char program_name[1024];
 138     uint32_t buf_size = sizeof(program_name);
 139     _NSGetExecutablePath(program_name, &buf_size);
 140     char *new_env = const_cast<char*>(info.dli_fname);
 141     if (dyld_insert_libraries) {
 142       // Append the runtime dylib name to the existing value of
 143       // DYLD_INSERT_LIBRARIES.
 144       new_env = (char*)allocator_for_env.Allocate(old_env_len + fname_len + 2);
 145       internal_strncpy(new_env, dyld_insert_libraries, old_env_len);
 146       new_env[old_env_len] = ':';
 147       // Copy fname_len and add a trailing zero.
 148       internal_strncpy(new_env + old_env_len + 1, info.dli_fname,
 149                        fname_len + 1);
 150       // Ok to use setenv() since the wrappers don't depend on the value of
 151       // asan_inited.
 152       setenv(kDyldInsertLibraries, new_env, /*overwrite*/1);
 153     } else {
 154       // Set DYLD_INSERT_LIBRARIES equal to the runtime dylib name.
 155       setenv(kDyldInsertLibraries, info.dli_fname, /*overwrite*/0);
 156     }
 157     VReport(1, "exec()-ing the program with\n");
 158     VReport(1, "%s=%s\n", kDyldInsertLibraries, new_env);
 159     VReport(1, "to enable ASan wrappers.\n");
 160     execv(program_name, *_NSGetArgv());
 161
 162     // We get here only if execv() failed.
 163     Report("ERROR: The process is launched without DYLD_INSERT_LIBRARIES, "
 164            "which is required for ASan to work. ASan tried to set the "
 165            "environment variable and re-execute itself, but execv() failed, "
 166            "possibly because of sandbox restrictions. Make sure to launch the "
 167            "executable with:\n%s=%s\n", kDyldInsertLibraries, new_env);
 168     CHECK("execv failed" && 0);
 169   }
 170
 171   if (!lib_is_in_env)
 172     return;
 173
 174   // DYLD_INSERT_LIBRARIES is set and contains the runtime library. Let's remove
 175   // the dylib from the environment variable, because interceptors are installed
 176   // and we don't want our children to inherit the variable.
 177
 178   uptr env_name_len = internal_strlen(kDyldInsertLibraries);
 179   // Allocate memory to hold the previous env var name, its value, the '='
 180   // sign and the '\0' char.
 181   char *new_env = (char*)allocator_for_env.Allocate(
 182       old_env_len + 2 + env_name_len);
 183   CHECK(new_env);
 184   internal_memset(new_env, '\0', old_env_len + 2 + env_name_len);
 185   internal_strncpy(new_env, kDyldInsertLibraries, env_name_len);
 186   new_env[env_name_len] = '=';
 187   char *new_env_pos = new_env + env_name_len + 1;
 188
 189   // Iterate over colon-separated pieces of |dyld_insert_libraries|.
 190   char *piece_start = dyld_insert_libraries;
 191   char *piece_end = NULL;
 192   char *old_env_end = dyld_insert_libraries + old_env_len;
 193   do {
 194     if (piece_start[0] == ':') piece_start++;
 195     piece_end = REAL(strchr)(piece_start, ':');
 196     if (!piece_end) piece_end = dyld_insert_libraries + old_env_len;
 197     if ((uptr)(piece_start - dyld_insert_libraries) > old_env_len) break;
 198     uptr piece_len = piece_end - piece_start;
 199
 200     char *filename_start =
 201         (char *)internal_memrchr(piece_start, '/', piece_len);
 202     uptr filename_len = piece_len;
 203     if (filename_start) {
 204       filename_start += 1;
 205       filename_len = piece_len - (filename_start - piece_start);
 206     } else {
 207       filename_start = piece_start;
 208     }
 209
 210     // If the current piece isn't the runtime library name,
 211     // append it to new_env.
 212     if ((dylib_name_len != filename_len) ||
 213         (internal_memcmp(filename_start, dylib_name, dylib_name_len) != 0)) {
 214       if (new_env_pos != new_env + env_name_len + 1) {
 215         new_env_pos[0] = ':';
 216         new_env_pos++;
 217       }
 218       internal_strncpy(new_env_pos, piece_start, piece_len);
 219       new_env_pos += piece_len;
 220     }
 221     // Move on to the next piece.
 222     piece_start = piece_end;
 223   } while (piece_start < old_env_end);
 224
 225   // Can't use setenv() here, because it requires the allocator to be
 226   // initialized.
 227   // FIXME: instead of filtering DYLD_INSERT_LIBRARIES here, do it in
 228   // a separate function called after InitializeAllocator().
 229   if (new_env_pos == new_env + env_name_len + 1) new_env = NULL;
 230   LeakyResetEnv(kDyldInsertLibraries, new_env);
 231 }
 232
 233 // No-op. Mac does not support static linkage anyway.
 234 void *AsanDoesNotSupportStaticLinkage() {
 235   return 0;
 236 }
 237
 238 // No-op. Mac does not support static linkage anyway.
 239 void AsanCheckDynamicRTPrereqs() {}
 240
 241 // No-op. Mac does not support static linkage anyway.
 242 void AsanCheckIncompatibleRT() {}
 243
 244 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
 245   UNIMPLEMENTED();
 246 }
 247
 248 // Support for the following functions from libdispatch on Mac OS:
 249 //   dispatch_async_f()
 250 //   dispatch_async()
 251 //   dispatch_sync_f()
 252 //   dispatch_sync()
 253 //   dispatch_after_f()
 254 //   dispatch_after()
 255 //   dispatch_group_async_f()
 256 //   dispatch_group_async()
 257 // TODO(glider): libdispatch API contains other functions that we don't support
 258 // yet.
 259 //
 260 // dispatch_sync() and dispatch_sync_f() are synchronous, although chances are
 261 // they can cause jobs to run on a thread different from the current one.
 262 // TODO(glider): if so, we need a test for this (otherwise we should remove
 263 // them).
 264 //
 265 // The following functions use dispatch_barrier_async_f() (which isn't a library
 266 // function but is exported) and are thus supported:
 267 //   dispatch_source_set_cancel_handler_f()
 268 //   dispatch_source_set_cancel_handler()
 269 //   dispatch_source_set_event_handler_f()
 270 //   dispatch_source_set_event_handler()
 271 //
 272 // The reference manual for Grand Central Dispatch is available at
 273 //   http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html
 274 // The implementation details are at
 275 //   http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c
 276
 277 typedef void* dispatch_group_t;
 278 typedef void* dispatch_queue_t;
 279 typedef void* dispatch_source_t;
 280 typedef u64 dispatch_time_t;
 281 typedef void (*dispatch_function_t)(void *block);
 282 typedef void* (*worker_t)(void *block);
 283
 284 // A wrapper for the ObjC blocks used to support libdispatch.
 285 typedef struct {
 286   void *block;
 287   dispatch_function_t func;
 288   u32 parent_tid;
 289 } asan_block_context_t;
 290
 291 ALWAYS_INLINE
 292 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
 293   AsanThread *t = GetCurrentThread();
 294   if (!t) {
 295     t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr,
 296                            parent_tid, stack, /* detached */ true);
 297     t->Init();
 298     asanThreadRegistry().StartThread(t->tid(), 0, 0);
 299     SetCurrentThread(t);
 300   }
 301 }
 302
 303 // For use by only those functions that allocated the context via
 304 // alloc_asan_context().
 305 extern "C"
 306 void asan_dispatch_call_block_and_release(void *block) {
 307   GET_STACK_TRACE_THREAD;
 308   asan_block_context_t *context = (asan_block_context_t*)block;
 309   VReport(2,
 310           "asan_dispatch_call_block_and_release(): "
 311           "context: %p, pthread_self: %p\n",
 312           block, pthread_self());
 313   asan_register_worker_thread(context->parent_tid, &stack);
 314   // Call the original dispatcher for the block.
 315   context->func(context->block);
 316   asan_free(context, &stack, FROM_MALLOC);
 317 }
 318
 319 }  // namespace __asan
 320
 321 using namespace __asan;  // NOLINT
 322
 323 // Wrap |ctxt| and |func| into an asan_block_context_t.
 324 // The caller retains control of the allocated context.
 325 extern "C"
 326 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
 327                                          BufferedStackTrace *stack) {
 328   asan_block_context_t *asan_ctxt =
 329       (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
 330   asan_ctxt->block = ctxt;
 331   asan_ctxt->func = func;
 332   asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
 333   return asan_ctxt;
 334 }
 335
 336 // Define interceptor for dispatch_*_f function with the three most common
 337 // parameters: dispatch_queue_t, context, dispatch_function_t.
 338 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f)                                \
 339   INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt,            \
 340                                   dispatch_function_t func) {                 \
 341     GET_STACK_TRACE_THREAD;                                                   \
 342     asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
 343     if (Verbosity() >= 2) {                                     \
 344       Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n",             \
 345              asan_ctxt, pthread_self());                                      \
 346       PRINT_CURRENT_STACK();                                                  \
 347     }                                                                         \
 348     return REAL(dispatch_x_f)(dq, (void*)asan_ctxt,                           \
 349                               asan_dispatch_call_block_and_release);          \
 350   }
 351
 352 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
 353 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
 354 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
 355
 356 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
 357                                     dispatch_queue_t dq, void *ctxt,
 358                                     dispatch_function_t func) {
 359   GET_STACK_TRACE_THREAD;
 360   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 361   if (Verbosity() >= 2) {
 362     Report("dispatch_after_f: %p\n", asan_ctxt);
 363     PRINT_CURRENT_STACK();
 364   }
 365   return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
 366                                 asan_dispatch_call_block_and_release);
 367 }
 368
 369 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
 370                                           dispatch_queue_t dq, void *ctxt,
 371                                           dispatch_function_t func) {
 372   GET_STACK_TRACE_THREAD;
 373   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 374   if (Verbosity() >= 2) {
 375     Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n",
 376            asan_ctxt, pthread_self());
 377     PRINT_CURRENT_STACK();
 378   }
 379   REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
 380                                asan_dispatch_call_block_and_release);
 381 }
 382
 383 #if !defined(MISSING_BLOCKS_SUPPORT)
 384 extern "C" {
 385 void dispatch_async(dispatch_queue_t dq, void(^work)(void));
 386 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
 387                           void(^work)(void));
 388 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
 389                     void(^work)(void));
 390 void dispatch_source_set_cancel_handler(dispatch_source_t ds,
 391                                         void(^work)(void));
 392 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
 393 }
 394
 395 #define GET_ASAN_BLOCK(work) \
 396   void (^asan_block)(void);  \
 397   int parent_tid = GetCurrentTidOrInvalid(); \
 398   asan_block = ^(void) { \
 399     GET_STACK_TRACE_THREAD; \
 400     asan_register_worker_thread(parent_tid, &stack); \
 401     work(); \
 402   }
 403
 404 INTERCEPTOR(void, dispatch_async,
 405             dispatch_queue_t dq, void(^work)(void)) {
 406   ENABLE_FRAME_POINTER;
 407   GET_ASAN_BLOCK(work);
 408   REAL(dispatch_async)(dq, asan_block);
 409 }
 410
 411 INTERCEPTOR(void, dispatch_group_async,
 412             dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
 413   ENABLE_FRAME_POINTER;
 414   GET_ASAN_BLOCK(work);
 415   REAL(dispatch_group_async)(dg, dq, asan_block);
 416 }
 417
 418 INTERCEPTOR(void, dispatch_after,
 419             dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
 420   ENABLE_FRAME_POINTER;
 421   GET_ASAN_BLOCK(work);
 422   REAL(dispatch_after)(when, queue, asan_block);
 423 }
 424
 425 INTERCEPTOR(void, dispatch_source_set_cancel_handler,
 426             dispatch_source_t ds, void(^work)(void)) {
 427   if (!work) {
 428     REAL(dispatch_source_set_cancel_handler)(ds, work);
 429     return;
 430   }
 431   ENABLE_FRAME_POINTER;
 432   GET_ASAN_BLOCK(work);
 433   REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
 434 }
 435
 436 INTERCEPTOR(void, dispatch_source_set_event_handler,
 437             dispatch_source_t ds, void(^work)(void)) {
 438   ENABLE_FRAME_POINTER;
 439   GET_ASAN_BLOCK(work);
 440   REAL(dispatch_source_set_event_handler)(ds, asan_block);
 441 }
 442 #endif
 443
 444 #endif  // SANITIZER_MAC