1//===-- asan_mac.cpp ------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10//
11// Mac-specific details.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common/sanitizer_platform.h"
15#if SANITIZER_APPLE
16
17#include "asan_interceptors.h"
18#include "asan_internal.h"
19#include "asan_mapping.h"
20#include "asan_stack.h"
21#include "asan_thread.h"
22#include "sanitizer_common/sanitizer_atomic.h"
23#include "sanitizer_common/sanitizer_libc.h"
24#include "sanitizer_common/sanitizer_mac.h"
25
26#include <dlfcn.h>
27#include <fcntl.h>
28#include <libkern/OSAtomic.h>
29#include <mach-o/dyld.h>
30#include <mach-o/getsect.h>
31#include <mach-o/loader.h>
32#include <pthread.h>
33#include <stdlib.h>  // for free()
34#include <sys/mman.h>
35#include <sys/resource.h>
36#include <sys/sysctl.h>
37#include <sys/ucontext.h>
38#include <unistd.h>
39
40// from <crt_externs.h>, but we don't have that file on iOS
41extern "C" {
42  extern char ***_NSGetArgv(void);
43  extern char ***_NSGetEnviron(void);
44}
45
46namespace __asan {
47
48void InitializePlatformInterceptors() {}
49void InitializePlatformExceptionHandlers() {}
50bool IsSystemHeapAddress (uptr addr) { return false; }
51
52// No-op. Mac does not support static linkage anyway.
53void *AsanDoesNotSupportStaticLinkage() {
54  return 0;
55}
56
57uptr FindDynamicShadowStart() {
58  return MapDynamicShadow(MemToShadowSize(kHighMemEnd), ASAN_SHADOW_SCALE,
59                          /*min_shadow_base_alignment*/ 0, kHighMemEnd);
60}
61
62// No-op. Mac does not support static linkage anyway.
63void AsanCheckDynamicRTPrereqs() {}
64
65// No-op. Mac does not support static linkage anyway.
66void AsanCheckIncompatibleRT() {}
67
68void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
69  // Find the Mach-O header for the image containing the needle
70  Dl_info info;
71  int err = dladdr(needle, &info);
72  if (err == 0) return;
73
74#if __LP64__
75  const struct mach_header_64 *mh = (struct mach_header_64 *)info.dli_fbase;
76#else
77  const struct mach_header *mh = (struct mach_header *)info.dli_fbase;
78#endif
79
80  // Look up the __asan_globals section in that image and register its globals
81  unsigned long size = 0;
82  __asan_global *globals = (__asan_global *)getsectiondata(
83      mh,
84      "__DATA", "__asan_globals",
85      &size);
86
87  if (!globals) return;
88  if (size % sizeof(__asan_global) != 0) return;
89  op(globals, size / sizeof(__asan_global));
90}
91
92void FlushUnneededASanShadowMemory(uptr p, uptr size) {
93  // Since asan's mapping is compacting, the shadow chunk may be
94  // not page-aligned, so we only flush the page-aligned portion.
95  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
96}
97
98// Support for the following functions from libdispatch on Mac OS:
99//   dispatch_async_f()
100//   dispatch_async()
101//   dispatch_sync_f()
102//   dispatch_sync()
103//   dispatch_after_f()
104//   dispatch_after()
105//   dispatch_group_async_f()
106//   dispatch_group_async()
107// TODO(glider): libdispatch API contains other functions that we don't support
108// yet.
109//
110// dispatch_sync() and dispatch_sync_f() are synchronous, although chances are
111// they can cause jobs to run on a thread different from the current one.
112// TODO(glider): if so, we need a test for this (otherwise we should remove
113// them).
114//
115// The following functions use dispatch_barrier_async_f() (which isn't a library
116// function but is exported) and are thus supported:
117//   dispatch_source_set_cancel_handler_f()
118//   dispatch_source_set_cancel_handler()
119//   dispatch_source_set_event_handler_f()
120//   dispatch_source_set_event_handler()
121//
122// The reference manual for Grand Central Dispatch is available at
123//   http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html
124// The implementation details are at
125//   http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c
126
127typedef void* dispatch_group_t;
128typedef void* dispatch_queue_t;
129typedef void* dispatch_source_t;
130typedef u64 dispatch_time_t;
131typedef void (*dispatch_function_t)(void *block);
132typedef void* (*worker_t)(void *block);
133typedef unsigned long dispatch_mach_reason;
134typedef void *dispatch_mach_msg_t;
135typedef int mach_error_t;
136typedef void *dispatch_mach_t;
137
138typedef void (*dispatch_mach_handler_function_t)(void *context,
139                                                 dispatch_mach_reason reason,
140                                                 dispatch_mach_msg_t message,
141                                                 mach_error_t error);
142#  if !defined(MISSING_BLOCKS_SUPPORT)
143typedef void (^dispatch_mach_handler_t)(dispatch_mach_reason reason,
144                                        dispatch_mach_msg_t message,
145                                        mach_error_t error);
146#  endif
147
148// A wrapper for the ObjC blocks used to support libdispatch.
149typedef struct {
150  void *block;
151  dispatch_function_t func;
152  u32 parent_tid;
153} asan_block_context_t;
154
155ALWAYS_INLINE
156void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
157  AsanThread *t = GetCurrentThread();
158  if (!t) {
159    t = AsanThread::Create(parent_tid, stack, /* detached */ true);
160    t->Init();
161    asanThreadRegistry().StartThread(t->tid(), GetTid(), ThreadType::Worker,
162                                     nullptr);
163    SetCurrentThread(t);
164  }
165}
166
167// For use by only those functions that allocated the context via
168// alloc_asan_context().
169extern "C"
170void asan_dispatch_call_block_and_release(void *block) {
171  GET_STACK_TRACE_THREAD;
172  asan_block_context_t *context = (asan_block_context_t*)block;
173  VReport(2,
174          "asan_dispatch_call_block_and_release(): "
175          "context: %p, pthread_self: %p\n",
176          block, (void*)pthread_self());
177  asan_register_worker_thread(context->parent_tid, &stack);
178  // Call the original dispatcher for the block.
179  context->func(context->block);
180  asan_free(context, &stack, FROM_MALLOC);
181}
182
183}  // namespace __asan
184
185using namespace __asan;
186
187// Wrap |ctxt| and |func| into an asan_block_context_t.
188// The caller retains control of the allocated context.
189extern "C"
190asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
191                                         BufferedStackTrace *stack) {
192  asan_block_context_t *asan_ctxt =
193      (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
194  asan_ctxt->block = ctxt;
195  asan_ctxt->func = func;
196  asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
197  return asan_ctxt;
198}
199
200// Define interceptor for dispatch_*_f function with the three most common
201// parameters: dispatch_queue_t, context, dispatch_function_t.
202#define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f)                                \
203  INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt,            \
204                                  dispatch_function_t func) {                 \
205    GET_STACK_TRACE_THREAD;                                                   \
206    asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
207    if (Verbosity() >= 2) {                                     \
208      Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n",             \
209             (void*)asan_ctxt, (void*)pthread_self());                        \
210      PRINT_CURRENT_STACK();                                                  \
211    }                                                                         \
212    return REAL(dispatch_x_f)(dq, (void*)asan_ctxt,                           \
213                              asan_dispatch_call_block_and_release);          \
214  }
215
216INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
217INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
218INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
219
220INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
221                                    dispatch_queue_t dq, void *ctxt,
222                                    dispatch_function_t func) {
223  GET_STACK_TRACE_THREAD;
224  asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
225  if (Verbosity() >= 2) {
226    Report("dispatch_after_f: %p\n", (void*)asan_ctxt);
227    PRINT_CURRENT_STACK();
228  }
229  return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
230                                asan_dispatch_call_block_and_release);
231}
232
233INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
234                                          dispatch_queue_t dq, void *ctxt,
235                                          dispatch_function_t func) {
236  GET_STACK_TRACE_THREAD;
237  asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
238  if (Verbosity() >= 2) {
239    Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n",
240           (void*)asan_ctxt, (void*)pthread_self());
241    PRINT_CURRENT_STACK();
242  }
243  REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
244                               asan_dispatch_call_block_and_release);
245}
246
247#if !defined(MISSING_BLOCKS_SUPPORT)
248extern "C" {
249void dispatch_async(dispatch_queue_t dq, void(^work)(void));
250void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
251                          void(^work)(void));
252void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
253                    void(^work)(void));
254void dispatch_source_set_cancel_handler(dispatch_source_t ds,
255                                        void(^work)(void));
256void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
257dispatch_mach_t dispatch_mach_create(const char *label, dispatch_queue_t queue,
258                                     dispatch_mach_handler_t handler);
259}
260
261#define GET_ASAN_BLOCK(work) \
262  void (^asan_block)(void);  \
263  int parent_tid = GetCurrentTidOrInvalid(); \
264  asan_block = ^(void) { \
265    GET_STACK_TRACE_THREAD; \
266    asan_register_worker_thread(parent_tid, &stack); \
267    work(); \
268  }
269
270INTERCEPTOR(void, dispatch_async,
271            dispatch_queue_t dq, void(^work)(void)) {
272  ENABLE_FRAME_POINTER;
273  GET_ASAN_BLOCK(work);
274  REAL(dispatch_async)(dq, asan_block);
275}
276
277INTERCEPTOR(void, dispatch_group_async,
278            dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
279  ENABLE_FRAME_POINTER;
280  GET_ASAN_BLOCK(work);
281  REAL(dispatch_group_async)(dg, dq, asan_block);
282}
283
284INTERCEPTOR(void, dispatch_after,
285            dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
286  ENABLE_FRAME_POINTER;
287  GET_ASAN_BLOCK(work);
288  REAL(dispatch_after)(when, queue, asan_block);
289}
290
291INTERCEPTOR(void, dispatch_source_set_cancel_handler,
292            dispatch_source_t ds, void(^work)(void)) {
293  if (!work) {
294    REAL(dispatch_source_set_cancel_handler)(ds, work);
295    return;
296  }
297  ENABLE_FRAME_POINTER;
298  GET_ASAN_BLOCK(work);
299  REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
300}
301
302INTERCEPTOR(void, dispatch_source_set_event_handler,
303            dispatch_source_t ds, void(^work)(void)) {
304  ENABLE_FRAME_POINTER;
305  GET_ASAN_BLOCK(work);
306  REAL(dispatch_source_set_event_handler)(ds, asan_block);
307}
308
309INTERCEPTOR(void *, dispatch_mach_create, const char *label,
310            dispatch_queue_t dq, dispatch_mach_handler_t handler) {
311  int parent_tid = GetCurrentTidOrInvalid();
312  return REAL(dispatch_mach_create)(
313      label, dq,
314      ^(dispatch_mach_reason reason, dispatch_mach_msg_t message,
315        mach_error_t error) {
316        GET_STACK_TRACE_THREAD;
317        asan_register_worker_thread(parent_tid, &stack);
318        handler(reason, message, error);
319      });
320}
321
322INTERCEPTOR(void *, dispatch_mach_create_f, const char *label,
323            dispatch_queue_t dq, void *ctxt,
324            dispatch_mach_handler_function_t handler) {
325  int parent_tid = GetCurrentTidOrInvalid();
326  return REAL(dispatch_mach_create)(
327      label, dq,
328      ^(dispatch_mach_reason reason, dispatch_mach_msg_t message,
329        mach_error_t error) {
330        GET_STACK_TRACE_THREAD;
331        asan_register_worker_thread(parent_tid, &stack);
332        handler(ctxt, reason, message, error);
333      });
334}
335
336#endif
337
338#endif  // SANITIZER_APPLE
339