libsanitizer/asan/asan_mac.cpp

   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_MAC
  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   uptr granularity = GetMmapGranularity();
  59   uptr alignment = 8 * granularity;
  60   uptr left_padding = granularity;
  61   uptr space_size = kHighShadowEnd + left_padding;
  62
  63   uptr largest_gap_found = 0;
  64   uptr max_occupied_addr = 0;
  65   VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
  66   uptr shadow_start =
  67       FindAvailableMemoryRange(space_size, alignment, granularity,
  68                                &largest_gap_found, &max_occupied_addr);
  69   // If the shadow doesn't fit, restrict the address space to make it fit.
  70   if (shadow_start == 0) {
  71     VReport(
  72         2,
  73         "Shadow doesn't fit, largest_gap_found = %p, max_occupied_addr = %p\n",
  74         largest_gap_found, max_occupied_addr);
  75     uptr new_max_vm = RoundDownTo(largest_gap_found << SHADOW_SCALE, alignment);
  76     if (new_max_vm < max_occupied_addr) {
  77       Report("Unable to find a memory range for dynamic shadow.\n");
  78       Report(
  79           "space_size = %p, largest_gap_found = %p, max_occupied_addr = %p, "
  80           "new_max_vm = %p\n",
  81           space_size, largest_gap_found, max_occupied_addr, new_max_vm);
  82       CHECK(0 && "cannot place shadow");
  83     }
  84     RestrictMemoryToMaxAddress(new_max_vm);
  85     kHighMemEnd = new_max_vm - 1;
  86     space_size = kHighShadowEnd + left_padding;
  87     VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
  88     shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity,
  89                                             nullptr, nullptr);
  90     if (shadow_start == 0) {
  91       Report("Unable to find a memory range after restricting VM.\n");
  92       CHECK(0 && "cannot place shadow after restricting vm");
  93     }
  94   }
  95   CHECK_NE((uptr)0, shadow_start);
  96   CHECK(IsAligned(shadow_start, alignment));
  97   return shadow_start;
  98 }
  99
 100 // No-op. Mac does not support static linkage anyway.
 101 void AsanCheckDynamicRTPrereqs() {}
 102
 103 // No-op. Mac does not support static linkage anyway.
 104 void AsanCheckIncompatibleRT() {}
 105
 106 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
 107   // Find the Mach-O header for the image containing the needle
 108   Dl_info info;
 109   int err = dladdr(needle, &info);
 110   if (err == 0) return;
 111
 112 #if __LP64__
 113   const struct mach_header_64 *mh = (struct mach_header_64 *)info.dli_fbase;
 114 #else
 115   const struct mach_header *mh = (struct mach_header *)info.dli_fbase;
 116 #endif
 117
 118   // Look up the __asan_globals section in that image and register its globals
 119   unsigned long size = 0;
 120   __asan_global *globals = (__asan_global *)getsectiondata(
 121       mh,
 122       "__DATA", "__asan_globals",
 123       &size);
 124
 125   if (!globals) return;
 126   if (size % sizeof(__asan_global) != 0) return;
 127   op(globals, size / sizeof(__asan_global));
 128 }
 129
 130 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
 131   UNIMPLEMENTED();
 132 }
 133
 134 // Support for the following functions from libdispatch on Mac OS:
 135 //   dispatch_async_f()
 136 //   dispatch_async()
 137 //   dispatch_sync_f()
 138 //   dispatch_sync()
 139 //   dispatch_after_f()
 140 //   dispatch_after()
 141 //   dispatch_group_async_f()
 142 //   dispatch_group_async()
 143 // TODO(glider): libdispatch API contains other functions that we don't support
 144 // yet.
 145 //
 146 // dispatch_sync() and dispatch_sync_f() are synchronous, although chances are
 147 // they can cause jobs to run on a thread different from the current one.
 148 // TODO(glider): if so, we need a test for this (otherwise we should remove
 149 // them).
 150 //
 151 // The following functions use dispatch_barrier_async_f() (which isn't a library
 152 // function but is exported) and are thus supported:
 153 //   dispatch_source_set_cancel_handler_f()
 154 //   dispatch_source_set_cancel_handler()
 155 //   dispatch_source_set_event_handler_f()
 156 //   dispatch_source_set_event_handler()
 157 //
 158 // The reference manual for Grand Central Dispatch is available at
 159 //   http://developer.apple.com/library/mac/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html
 160 // The implementation details are at
 161 //   http://libdispatch.macosforge.org/trac/browser/trunk/src/queue.c
 162
 163 typedef void* dispatch_group_t;
 164 typedef void* dispatch_queue_t;
 165 typedef void* dispatch_source_t;
 166 typedef u64 dispatch_time_t;
 167 typedef void (*dispatch_function_t)(void *block);
 168 typedef void* (*worker_t)(void *block);
 169
 170 // A wrapper for the ObjC blocks used to support libdispatch.
 171 typedef struct {
 172   void *block;
 173   dispatch_function_t func;
 174   u32 parent_tid;
 175 } asan_block_context_t;
 176
 177 ALWAYS_INLINE
 178 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
 179   AsanThread *t = GetCurrentThread();
 180   if (!t) {
 181     t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr,
 182                            parent_tid, stack, /* detached */ true);
 183     t->Init();
 184     asanThreadRegistry().StartThread(t->tid(), GetTid(), ThreadType::Worker,
 185                                      nullptr);
 186     SetCurrentThread(t);
 187   }
 188 }
 189
 190 // For use by only those functions that allocated the context via
 191 // alloc_asan_context().
 192 extern "C"
 193 void asan_dispatch_call_block_and_release(void *block) {
 194   GET_STACK_TRACE_THREAD;
 195   asan_block_context_t *context = (asan_block_context_t*)block;
 196   VReport(2,
 197           "asan_dispatch_call_block_and_release(): "
 198           "context: %p, pthread_self: %p\n",
 199           block, pthread_self());
 200   asan_register_worker_thread(context->parent_tid, &stack);
 201   // Call the original dispatcher for the block.
 202   context->func(context->block);
 203   asan_free(context, &stack, FROM_MALLOC);
 204 }
 205
 206 }  // namespace __asan
 207
 208 using namespace __asan;
 209
 210 // Wrap |ctxt| and |func| into an asan_block_context_t.
 211 // The caller retains control of the allocated context.
 212 extern "C"
 213 asan_block_context_t *alloc_asan_context(void *ctxt, dispatch_function_t func,
 214                                          BufferedStackTrace *stack) {
 215   asan_block_context_t *asan_ctxt =
 216       (asan_block_context_t*) asan_malloc(sizeof(asan_block_context_t), stack);
 217   asan_ctxt->block = ctxt;
 218   asan_ctxt->func = func;
 219   asan_ctxt->parent_tid = GetCurrentTidOrInvalid();
 220   return asan_ctxt;
 221 }
 222
 223 // Define interceptor for dispatch_*_f function with the three most common
 224 // parameters: dispatch_queue_t, context, dispatch_function_t.
 225 #define INTERCEPT_DISPATCH_X_F_3(dispatch_x_f)                                \
 226   INTERCEPTOR(void, dispatch_x_f, dispatch_queue_t dq, void *ctxt,            \
 227                                   dispatch_function_t func) {                 \
 228     GET_STACK_TRACE_THREAD;                                                   \
 229     asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack); \
 230     if (Verbosity() >= 2) {                                     \
 231       Report(#dispatch_x_f "(): context: %p, pthread_self: %p\n",             \
 232              asan_ctxt, pthread_self());                                      \
 233       PRINT_CURRENT_STACK();                                                  \
 234     }                                                                         \
 235     return REAL(dispatch_x_f)(dq, (void*)asan_ctxt,                           \
 236                               asan_dispatch_call_block_and_release);          \
 237   }
 238
 239 INTERCEPT_DISPATCH_X_F_3(dispatch_async_f)
 240 INTERCEPT_DISPATCH_X_F_3(dispatch_sync_f)
 241 INTERCEPT_DISPATCH_X_F_3(dispatch_barrier_async_f)
 242
 243 INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
 244                                     dispatch_queue_t dq, void *ctxt,
 245                                     dispatch_function_t func) {
 246   GET_STACK_TRACE_THREAD;
 247   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 248   if (Verbosity() >= 2) {
 249     Report("dispatch_after_f: %p\n", asan_ctxt);
 250     PRINT_CURRENT_STACK();
 251   }
 252   return REAL(dispatch_after_f)(when, dq, (void*)asan_ctxt,
 253                                 asan_dispatch_call_block_and_release);
 254 }
 255
 256 INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
 257                                           dispatch_queue_t dq, void *ctxt,
 258                                           dispatch_function_t func) {
 259   GET_STACK_TRACE_THREAD;
 260   asan_block_context_t *asan_ctxt = alloc_asan_context(ctxt, func, &stack);
 261   if (Verbosity() >= 2) {
 262     Report("dispatch_group_async_f(): context: %p, pthread_self: %p\n",
 263            asan_ctxt, pthread_self());
 264     PRINT_CURRENT_STACK();
 265   }
 266   REAL(dispatch_group_async_f)(group, dq, (void*)asan_ctxt,
 267                                asan_dispatch_call_block_and_release);
 268 }
 269
 270 #if !defined(MISSING_BLOCKS_SUPPORT)
 271 extern "C" {
 272 void dispatch_async(dispatch_queue_t dq, void(^work)(void));
 273 void dispatch_group_async(dispatch_group_t dg, dispatch_queue_t dq,
 274                           void(^work)(void));
 275 void dispatch_after(dispatch_time_t when, dispatch_queue_t queue,
 276                     void(^work)(void));
 277 void dispatch_source_set_cancel_handler(dispatch_source_t ds,
 278                                         void(^work)(void));
 279 void dispatch_source_set_event_handler(dispatch_source_t ds, void(^work)(void));
 280 }
 281
 282 #define GET_ASAN_BLOCK(work) \
 283   void (^asan_block)(void);  \
 284   int parent_tid = GetCurrentTidOrInvalid(); \
 285   asan_block = ^(void) { \
 286     GET_STACK_TRACE_THREAD; \
 287     asan_register_worker_thread(parent_tid, &stack); \
 288     work(); \
 289   }
 290
 291 INTERCEPTOR(void, dispatch_async,
 292             dispatch_queue_t dq, void(^work)(void)) {
 293   ENABLE_FRAME_POINTER;
 294   GET_ASAN_BLOCK(work);
 295   REAL(dispatch_async)(dq, asan_block);
 296 }
 297
 298 INTERCEPTOR(void, dispatch_group_async,
 299             dispatch_group_t dg, dispatch_queue_t dq, void(^work)(void)) {
 300   ENABLE_FRAME_POINTER;
 301   GET_ASAN_BLOCK(work);
 302   REAL(dispatch_group_async)(dg, dq, asan_block);
 303 }
 304
 305 INTERCEPTOR(void, dispatch_after,
 306             dispatch_time_t when, dispatch_queue_t queue, void(^work)(void)) {
 307   ENABLE_FRAME_POINTER;
 308   GET_ASAN_BLOCK(work);
 309   REAL(dispatch_after)(when, queue, asan_block);
 310 }
 311
 312 INTERCEPTOR(void, dispatch_source_set_cancel_handler,
 313             dispatch_source_t ds, void(^work)(void)) {
 314   if (!work) {
 315     REAL(dispatch_source_set_cancel_handler)(ds, work);
 316     return;
 317   }
 318   ENABLE_FRAME_POINTER;
 319   GET_ASAN_BLOCK(work);
 320   REAL(dispatch_source_set_cancel_handler)(ds, asan_block);
 321 }
 322
 323 INTERCEPTOR(void, dispatch_source_set_event_handler,
 324             dispatch_source_t ds, void(^work)(void)) {
 325   ENABLE_FRAME_POINTER;
 326   GET_ASAN_BLOCK(work);
 327   REAL(dispatch_source_set_event_handler)(ds, asan_block);
 328 }
 329 #endif
 330
 331 #endif  // SANITIZER_MAC