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
41 extern "C" {
42   extern char ***_NSGetArgv(void);
43   extern char ***_NSGetEnviron(void);
44 }
45 
46 namespace __asan {
47 
48 void InitializePlatformInterceptors() {}
49 void InitializePlatformExceptionHandlers() {}
50 bool IsSystemHeapAddress (uptr addr) { return false; }
51 
52 // No-op. Mac does not support static linkage anyway.
53 void *AsanDoesNotSupportStaticLinkage() {
54   return 0;
55 }
56 
57 uptr 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.
63 void AsanCheckDynamicRTPrereqs() {}
64 
65 // No-op. Mac does not support static linkage anyway.
66 void AsanCheckIncompatibleRT() {}
67 
68 void 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 
92 void 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 
127 typedef void* dispatch_group_t;
128 typedef void* dispatch_queue_t;
129 typedef void* dispatch_source_t;
130 typedef u64 dispatch_time_t;
131 typedef void (*dispatch_function_t)(void *block);
132 typedef void* (*worker_t)(void *block);
133 
134 // A wrapper for the ObjC blocks used to support libdispatch.
135 typedef struct {
136   void *block;
137   dispatch_function_t func;
138   u32 parent_tid;
139 } asan_block_context_t;
140 
141 ALWAYS_INLINE
142 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
143   AsanThread *t = GetCurrentThread();
144   if (!t) {
145     t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr,
146                            parent_tid, stack, /* detached */ true);
147     t->Init();
148     asanThreadRegistry().StartThread(t->tid(), GetTid(), ThreadType::Worker,
149                                      nullptr);
150     SetCurrentThread(t);
151   }
152 }
153 
154 // For use by only those functions that allocated the context via
155 // alloc_asan_context().
156 extern "C"
157 void asan_dispatch_call_block_and_release(void *block) {
158   GET_STACK_TRACE_THREAD;
159   asan_block_context_t *context = (asan_block_context_t*)block;
160   VReport(2,
161           "asan_dispatch_call_block_and_release(): "
162           "context: %p, pthread_self: %p\n",
163           block, pthread_self());
164   asan_register_worker_thread(context->parent_tid, &stack);
165   // Call the original dispatcher for the block.
166   context->func(context->block);
167   asan_free(context, &stack, FROM_MALLOC);
168 }
169 
170 }  // namespace __asan
171 
172 using namespace __asan;
173 
174 // Wrap |ctxt| and |func| into an asan_block_context_t.
175 // The caller retains control of the allocated context.
176 extern "C"
177 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
178                                          BufferedStackTrace *stack) {
179   asan_block_context_t *asan_ctxt =
180       (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
181   asan_ctxt->block = ctxt;
182   asan_ctxt->func = func;
183   asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
184   return asan_ctxt;
185 }
186 
187 // Define interceptor for dispatch_*_f function with the three most common
188 // parameters: dispatch_queue_t, context, dispatch_function_t.
189 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f)                                \
190   INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt,            \
191                                   dispatch_function_t func) {                 \
192     GET_STACK_TRACE_THREAD;                                                   \
193     asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
194     if (Verbosity() >= 2) {                                     \
195       Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n",             \
196              asan_ctxt, pthread_self());                                      \
197       PRINT_CURRENT_STACK();                                                  \
198     }                                                                         \
199     return REAL(dispatch_x_f)(dq, (void*)asan_ctxt,                           \
200                               asan_dispatch_call_block_and_release);          \
201   }
202 
203 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
204 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
205 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
206 
207 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
208                                     dispatch_queue_t dq, void *ctxt,
209                                     dispatch_function_t func) {
210   GET_STACK_TRACE_THREAD;
211   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
212   if (Verbosity() >= 2) {
213     Report("dispatch_after_f: %p\n", asan_ctxt);
214     PRINT_CURRENT_STACK();
215   }
216   return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
217                                 asan_dispatch_call_block_and_release);
218 }
219 
220 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
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_group_async_f(): context: %p, pthread_self: %p\n",
227            asan_ctxt, pthread_self());
228     PRINT_CURRENT_STACK();
229   }
230   REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
231                                asan_dispatch_call_block_and_release);
232 }
233 
234 #if !defined(MISSING_BLOCKS_SUPPORT)
235 extern "C" {
236 void dispatch_async(dispatch_queue_t dq, void(^work)(void));
237 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
238                           void(^work)(void));
239 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
240                     void(^work)(void));
241 void dispatch_source_set_cancel_handler(dispatch_source_t ds,
242                                         void(^work)(void));
243 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
244 }
245 
246 #define GET_ASAN_BLOCK(work) \
247   void (^asan_block)(void);  \
248   int parent_tid = GetCurrentTidOrInvalid(); \
249   asan_block = ^(void) { \
250     GET_STACK_TRACE_THREAD; \
251     asan_register_worker_thread(parent_tid, &stack); \
252     work(); \
253   }
254 
255 INTERCEPTOR(void, dispatch_async,
256             dispatch_queue_t dq, void(^work)(void)) {
257   ENABLE_FRAME_POINTER;
258   GET_ASAN_BLOCK(work);
259   REAL(dispatch_async)(dq, asan_block);
260 }
261 
262 INTERCEPTOR(void, dispatch_group_async,
263             dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
264   ENABLE_FRAME_POINTER;
265   GET_ASAN_BLOCK(work);
266   REAL(dispatch_group_async)(dg, dq, asan_block);
267 }
268 
269 INTERCEPTOR(void, dispatch_after,
270             dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
271   ENABLE_FRAME_POINTER;
272   GET_ASAN_BLOCK(work);
273   REAL(dispatch_after)(when, queue, asan_block);
274 }
275 
276 INTERCEPTOR(void, dispatch_source_set_cancel_handler,
277             dispatch_source_t ds, void(^work)(void)) {
278   if (!work) {
279     REAL(dispatch_source_set_cancel_handler)(ds, work);
280     return;
281   }
282   ENABLE_FRAME_POINTER;
283   GET_ASAN_BLOCK(work);
284   REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
285 }
286 
287 INTERCEPTOR(void, dispatch_source_set_event_handler,
288             dispatch_source_t ds, void(^work)(void)) {
289   ENABLE_FRAME_POINTER;
290   GET_ASAN_BLOCK(work);
291   REAL(dispatch_source_set_event_handler)(ds, asan_block);
292 }
293 #endif
294 
295 #endif  // SANITIZER_APPLE
296