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