libsanitizer/sanitizer_common/sanitizer_procmaps_mac.cpp

   1 //===-- sanitizer_procmaps_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 // Information about the process mappings (Mac-specific parts).
  10 //===----------------------------------------------------------------------===//
  11
  12 #include "sanitizer_platform.h"
  13 #if SANITIZER_APPLE
  14 #include "sanitizer_common.h"
  15 #include "sanitizer_placement_new.h"
  16 #include "sanitizer_procmaps.h"
  17
  18 #include <mach-o/dyld.h>
  19 #include <mach-o/loader.h>
  20 #include <mach/mach.h>
  21
  22 // These are not available in older macOS SDKs.
  23 #ifndef CPU_SUBTYPE_X86_64_H
  24 #define CPU_SUBTYPE_X86_64_H  ((cpu_subtype_t)8)   /* Haswell */
  25 #endif
  26 #ifndef CPU_SUBTYPE_ARM_V7S
  27 #define CPU_SUBTYPE_ARM_V7S   ((cpu_subtype_t)11)  /* Swift */
  28 #endif
  29 #ifndef CPU_SUBTYPE_ARM_V7K
  30 #define CPU_SUBTYPE_ARM_V7K   ((cpu_subtype_t)12)
  31 #endif
  32 #ifndef CPU_TYPE_ARM64
  33 #define CPU_TYPE_ARM64        (CPU_TYPE_ARM | CPU_ARCH_ABI64)
  34 #endif
  35
  36 namespace __sanitizer {
  37
  38 // Contains information used to iterate through sections.
  39 struct MemoryMappedSegmentData {
  40   char name[kMaxSegName];
  41   uptr nsects;
  42   const char *current_load_cmd_addr;
  43   u32 lc_type;
  44   uptr base_virt_addr;
  45   uptr addr_mask;
  46 };
  47
  48 template <typename Section>
  49 static void NextSectionLoad(LoadedModule *module, MemoryMappedSegmentData *data,
  50                             bool isWritable) {
  51   const Section *sc = (const Section *)data->current_load_cmd_addr;
  52   data->current_load_cmd_addr += sizeof(Section);
  53
  54   uptr sec_start = (sc->addr & data->addr_mask) + data->base_virt_addr;
  55   uptr sec_end = sec_start + sc->size;
  56   module->addAddressRange(sec_start, sec_end, /*executable=*/false, isWritable,
  57                           sc->sectname);
  58 }
  59
  60 void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
  61   // Don't iterate over sections when the caller hasn't set up the
  62   // data pointer, when there are no sections, or when the segment
  63   // is executable. Avoid iterating over executable sections because
  64   // it will confuse libignore, and because the extra granularity
  65   // of information is not needed by any sanitizers.
  66   if (!data_ || !data_->nsects || IsExecutable()) {
  67     module->addAddressRange(start, end, IsExecutable(), IsWritable(),
  68                             data_ ? data_->name : nullptr);
  69     return;
  70   }
  71
  72   do {
  73     if (data_->lc_type == LC_SEGMENT) {
  74       NextSectionLoad<struct section>(module, data_, IsWritable());
  75 #ifdef MH_MAGIC_64
  76     } else if (data_->lc_type == LC_SEGMENT_64) {
  77       NextSectionLoad<struct section_64>(module, data_, IsWritable());
  78 #endif
  79     }
  80   } while (--data_->nsects);
  81 }
  82
  83 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
  84   Reset();
  85 }
  86
  87 MemoryMappingLayout::~MemoryMappingLayout() {
  88 }
  89
  90 bool MemoryMappingLayout::Error() const {
  91   return false;
  92 }
  93
  94 // More information about Mach-O headers can be found in mach-o/loader.h
  95 // Each Mach-O image has a header (mach_header or mach_header_64) starting with
  96 // a magic number, and a list of linker load commands directly following the
  97 // header.
  98 // A load command is at least two 32-bit words: the command type and the
  99 // command size in bytes. We're interested only in segment load commands
 100 // (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
 101 // into the task's address space.
 102 // The |vmaddr|, |vmsize| and |fileoff| fields of segment_command or
 103 // segment_command_64 correspond to the memory address, memory size and the
 104 // file offset of the current memory segment.
 105 // Because these fields are taken from the images as is, one needs to add
 106 // _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.
 107
 108 void MemoryMappingLayout::Reset() {
 109   // Count down from the top.
 110   // TODO(glider): as per man 3 dyld, iterating over the headers with
 111   // _dyld_image_count is thread-unsafe. We need to register callbacks for
 112   // adding and removing images which will invalidate the MemoryMappingLayout
 113   // state.
 114   data_.current_image = _dyld_image_count();
 115   data_.current_load_cmd_count = -1;
 116   data_.current_load_cmd_addr = 0;
 117   data_.current_magic = 0;
 118   data_.current_filetype = 0;
 119   data_.current_arch = kModuleArchUnknown;
 120   internal_memset(data_.current_uuid, 0, kModuleUUIDSize);
 121 }
 122
 123 // The dyld load address should be unchanged throughout process execution,
 124 // and it is expensive to compute once many libraries have been loaded,
 125 // so cache it here and do not reset.
 126 static mach_header *dyld_hdr = 0;
 127 static const char kDyldPath[] = "/usr/lib/dyld";
 128 static const int kDyldImageIdx = -1;
 129
 130 // static
 131 void MemoryMappingLayout::CacheMemoryMappings() {
 132   // No-op on Mac for now.
 133 }
 134
 135 void MemoryMappingLayout::LoadFromCache() {
 136   // No-op on Mac for now.
 137 }
 138
 139 static bool IsDyldHdr(const mach_header *hdr) {
 140   return (hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) &&
 141          hdr->filetype == MH_DYLINKER;
 142 }
 143
 144 // _dyld_get_image_header() and related APIs don't report dyld itself.
 145 // We work around this by manually recursing through the memory map
 146 // until we hit a Mach header matching dyld instead. These recurse
 147 // calls are expensive, but the first memory map generation occurs
 148 // early in the process, when dyld is one of the only images loaded,
 149 // so it will be hit after only a few iterations.  These assumptions don't
 150 // hold on macOS 13+ anymore (dyld itself has moved into the shared cache).
 151
 152 // FIXME: Unfortunately, the upstream revised version to deal with macOS 13+
 153 // is incompatible with GCC and also uses APIs not available on earlier
 154 // systems which we support; backed out for now.
 155
 156 static mach_header *GetDyldImageHeaderViaVMRegion() {
 157   vm_address_t address = 0;
 158
 159   while (true) {
 160     vm_size_t size = 0;
 161     unsigned depth = 1;
 162     struct vm_region_submap_info_64 info;
 163     mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
 164     kern_return_t err =
 165         vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
 166                              (vm_region_info_t)&info, &count);
 167     if (err != KERN_SUCCESS) return nullptr;
 168
 169     if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
 170       mach_header *hdr = (mach_header *)address;
 171       if (IsDyldHdr(hdr)) {
 172         return hdr;
 173       }
 174     }
 175     address += size;
 176   }
 177 }
 178
 179 const mach_header *get_dyld_hdr() {
 180   if (!dyld_hdr) {
 181     // On macOS 13+, dyld itself has moved into the shared cache.  Looking it up
 182     // via vm_region_recurse_64() causes spins/hangs/crashes.
 183     // FIXME: find a way to do this compatible with GCC.
 184     if (GetMacosAlignedVersion() >= MacosVersion(13, 0)) {
 185         VReport(1,
 186                 "looking up the dyld image header in the shared cache on "
 187                 "macOS 13+ is not yet supported.  Falling back to "
 188                 "lookup via vm_region_recurse_64().\n");
 189         dyld_hdr = GetDyldImageHeaderViaVMRegion();
 190     } else {
 191       dyld_hdr = GetDyldImageHeaderViaVMRegion();
 192     }
 193     CHECK(dyld_hdr);
 194   }
 195
 196   return dyld_hdr;
 197 }
 198
 199 // Next and NextSegmentLoad were inspired by base/sysinfo.cc in
 200 // Google Perftools, https://github.com/gperftools/gperftools.
 201
 202 // NextSegmentLoad scans the current image for the next segment load command
 203 // and returns the start and end addresses and file offset of the corresponding
 204 // segment.
 205 // Note that the segment addresses are not necessarily sorted.
 206 template <u32 kLCSegment, typename SegmentCommand>
 207 static bool NextSegmentLoad(MemoryMappedSegment *segment,
 208                             MemoryMappedSegmentData *seg_data,
 209                             MemoryMappingLayoutData *layout_data) {
 210   const char *lc = layout_data->current_load_cmd_addr;
 211
 212   layout_data->current_load_cmd_addr += ((const load_command *)lc)->cmdsize;
 213   layout_data->current_load_cmd_count--;
 214   if (((const load_command *)lc)->cmd == kLCSegment) {
 215     const SegmentCommand* sc = (const SegmentCommand *)lc;
 216     uptr base_virt_addr, addr_mask;
 217     if (layout_data->current_image == kDyldImageIdx) {
 218       base_virt_addr = (uptr)get_dyld_hdr();
 219       // vmaddr is masked with 0xfffff because on macOS versions < 10.12,
 220       // it contains an absolute address rather than an offset for dyld.
 221       // To make matters even more complicated, this absolute address
 222       // isn't actually the absolute segment address, but the offset portion
 223       // of the address is accurate when combined with the dyld base address,
 224       // and the mask will give just this offset.
 225       addr_mask = 0xfffff;
 226     } else {
 227       base_virt_addr =
 228           (uptr)_dyld_get_image_vmaddr_slide(layout_data->current_image);
 229       addr_mask = ~0;
 230     }
 231
 232     segment->start = (sc->vmaddr & addr_mask) + base_virt_addr;
 233     segment->end = segment->start + sc->vmsize;
 234     // Most callers don't need section information, so only fill this struct
 235     // when required.
 236     if (seg_data) {
 237       seg_data->nsects = sc->nsects;
 238       seg_data->current_load_cmd_addr =
 239           (const char *)lc + sizeof(SegmentCommand);
 240       seg_data->lc_type = kLCSegment;
 241       seg_data->base_virt_addr = base_virt_addr;
 242       seg_data->addr_mask = addr_mask;
 243       internal_strncpy(seg_data->name, sc->segname,
 244                        ARRAY_SIZE(seg_data->name));
 245     }
 246
 247     // Return the initial protection.
 248     segment->protection = sc->initprot;
 249     segment->offset = (layout_data->current_filetype ==
 250                        /*MH_EXECUTE*/ 0x2)
 251                           ? sc->vmaddr
 252                           : sc->fileoff;
 253     if (segment->filename) {
 254       const char *src = (layout_data->current_image == kDyldImageIdx)
 255                             ? kDyldPath
 256                             : _dyld_get_image_name(layout_data->current_image);
 257       internal_strncpy(segment->filename, src, segment->filename_size);
 258     }
 259     segment->arch = layout_data->current_arch;
 260     internal_memcpy(segment->uuid, layout_data->current_uuid, kModuleUUIDSize);
 261     return true;
 262   }
 263   return false;
 264 }
 265
 266 ModuleArch ModuleArchFromCpuType(cpu_type_t cputype, cpu_subtype_t cpusubtype) {
 267   cpusubtype = cpusubtype & ~CPU_SUBTYPE_MASK;
 268   switch (cputype) {
 269     case CPU_TYPE_I386:
 270       return kModuleArchI386;
 271     case CPU_TYPE_X86_64:
 272       if (cpusubtype == CPU_SUBTYPE_X86_64_ALL) return kModuleArchX86_64;
 273       if (cpusubtype == CPU_SUBTYPE_X86_64_H) return kModuleArchX86_64H;
 274       CHECK(0 && "Invalid subtype of x86_64");
 275       return kModuleArchUnknown;
 276     case CPU_TYPE_ARM:
 277       if (cpusubtype == CPU_SUBTYPE_ARM_V6) return kModuleArchARMV6;
 278       if (cpusubtype == CPU_SUBTYPE_ARM_V7) return kModuleArchARMV7;
 279       if (cpusubtype == CPU_SUBTYPE_ARM_V7S) return kModuleArchARMV7S;
 280       if (cpusubtype == CPU_SUBTYPE_ARM_V7K) return kModuleArchARMV7K;
 281       CHECK(0 && "Invalid subtype of ARM");
 282       return kModuleArchUnknown;
 283     case CPU_TYPE_ARM64:
 284       return kModuleArchARM64;
 285     default:
 286       CHECK(0 && "Invalid CPU type");
 287       return kModuleArchUnknown;
 288   }
 289 }
 290
 291 static const load_command *NextCommand(const load_command *lc) {
 292   return (const load_command *)((const char *)lc + lc->cmdsize);
 293 }
 294
 295 static void FindUUID(const load_command *first_lc, u8 *uuid_output) {
 296   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
 297     if (lc->cmd != LC_UUID) continue;
 298
 299     const uuid_command *uuid_lc = (const uuid_command *)lc;
 300     const uint8_t *uuid = &uuid_lc->uuid[0];
 301     internal_memcpy(uuid_output, uuid, kModuleUUIDSize);
 302     return;
 303   }
 304 }
 305
 306 static bool IsModuleInstrumented(const load_command *first_lc) {
 307   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
 308     if (lc->cmd != LC_LOAD_DYLIB) continue;
 309
 310     const dylib_command *dylib_lc = (const dylib_command *)lc;
 311     uint32_t dylib_name_offset = dylib_lc->dylib.name.offset;
 312     const char *dylib_name = ((const char *)dylib_lc) + dylib_name_offset;
 313     dylib_name = StripModuleName(dylib_name);
 314     if (dylib_name != 0 && (internal_strstr(dylib_name, "libclang_rt."))) {
 315       return true;
 316     }
 317   }
 318   return false;
 319 }
 320
 321 const ImageHeader *MemoryMappingLayout::CurrentImageHeader() {
 322   const mach_header *hdr = (data_.current_image == kDyldImageIdx)
 323                                 ? get_dyld_hdr()
 324                                 : _dyld_get_image_header(data_.current_image);
 325   return (const ImageHeader *)hdr;
 326 }
 327
 328 bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
 329   for (; data_.current_image >= kDyldImageIdx; data_.current_image--) {
 330     const mach_header *hdr = (const mach_header *)CurrentImageHeader();
 331     if (!hdr) continue;
 332     if (data_.current_load_cmd_count < 0) {
 333       // Set up for this image;
 334       data_.current_load_cmd_count = hdr->ncmds;
 335       data_.current_magic = hdr->magic;
 336       data_.current_filetype = hdr->filetype;
 337       data_.current_arch = ModuleArchFromCpuType(hdr->cputype, hdr->cpusubtype);
 338       switch (data_.current_magic) {
 339 #ifdef MH_MAGIC_64
 340         case MH_MAGIC_64: {
 341           data_.current_load_cmd_addr =
 342               (const char *)hdr + sizeof(mach_header_64);
 343           break;
 344         }
 345 #endif
 346         case MH_MAGIC: {
 347           data_.current_load_cmd_addr = (const char *)hdr + sizeof(mach_header);
 348           break;
 349         }
 350         default: {
 351           continue;
 352         }
 353       }
 354       FindUUID((const load_command *)data_.current_load_cmd_addr,
 355                data_.current_uuid);
 356       data_.current_instrumented = IsModuleInstrumented(
 357           (const load_command *)data_.current_load_cmd_addr);
 358     }
 359
 360     while (data_.current_load_cmd_count > 0) {
 361       switch (data_.current_magic) {
 362         // data_.current_magic may be only one of MH_MAGIC, MH_MAGIC_64.
 363 #ifdef MH_MAGIC_64
 364         case MH_MAGIC_64: {
 365           if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
 366                   segment, segment->data_, &data_))
 367             return true;
 368           break;
 369         }
 370 #endif
 371         case MH_MAGIC: {
 372           if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
 373                   segment, segment->data_, &data_))
 374             return true;
 375           break;
 376         }
 377       }
 378     }
 379     // If we get here, no more load_cmd's in this image talk about
 380     // segments.  Go on to the next image.
 381     data_.current_load_cmd_count = -1; // This will trigger loading next image
 382   }
 383   return false;
 384 }
 385
 386 void MemoryMappingLayout::DumpListOfModules(
 387     InternalMmapVectorNoCtor<LoadedModule> *modules) {
 388   Reset();
 389   InternalMmapVector<char> module_name(kMaxPathLength);
 390   MemoryMappedSegment segment(module_name.data(), module_name.size());
 391   MemoryMappedSegmentData data;
 392   segment.data_ = &data;
 393   while (Next(&segment)) {
 394     if (segment.filename[0] == '\0') continue;
 395     LoadedModule *cur_module = nullptr;
 396     if (!modules->empty() &&
 397         0 == internal_strcmp(segment.filename, modules->back().full_name())) {
 398       cur_module = &modules->back();
 399     } else {
 400       modules->push_back(LoadedModule());
 401       cur_module = &modules->back();
 402       cur_module->set(segment.filename, segment.start, segment.arch,
 403                       segment.uuid, data_.current_instrumented);
 404     }
 405     segment.AddAddressRanges(cur_module);
 406   }
 407 }
 408
 409 }  // namespace __sanitizer
 410
 411 #endif  // SANITIZER_APPLE