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