compiler-rt/lib/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_MAC
  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 // _dyld_get_image_header() and related APIs don't report dyld itself.
 140 // We work around this by manually recursing through the memory map
 141 // until we hit a Mach header matching dyld instead. These recurse
 142 // calls are expensive, but the first memory map generation occurs
 143 // early in the process, when dyld is one of the only images loaded,
 144 // so it will be hit after only a few iterations.
 145 static mach_header *get_dyld_image_header() {
 146   vm_address_t address = 0;
 147
 148   while (true) {
 149     vm_size_t size = 0;
 150     unsigned depth = 1;
 151     struct vm_region_submap_info_64 info;
 152     mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
 153     kern_return_t err =
 154         vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
 155                              (vm_region_info_t)&info, &count);
 156     if (err != KERN_SUCCESS) return nullptr;
 157
 158     if (size >= sizeof(mach_header) && info.protection & kProtectionRead) {
 159       mach_header *hdr = (mach_header *)address;
 160       if ((hdr->magic == MH_MAGIC || hdr->magic == MH_MAGIC_64) &&
 161           hdr->filetype == MH_DYLINKER) {
 162         return hdr;
 163       }
 164     }
 165     address += size;
 166   }
 167 }
 168
 169 const mach_header *get_dyld_hdr() {
 170   if (!dyld_hdr) dyld_hdr = get_dyld_image_header();
 171
 172   return dyld_hdr;
 173 }
 174
 175 // Next and NextSegmentLoad were inspired by base/sysinfo.cc in
 176 // Google Perftools, https://github.com/gperftools/gperftools.
 177
 178 // NextSegmentLoad scans the current image for the next segment load command
 179 // and returns the start and end addresses and file offset of the corresponding
 180 // segment.
 181 // Note that the segment addresses are not necessarily sorted.
 182 template <u32 kLCSegment, typename SegmentCommand>
 183 static bool NextSegmentLoad(MemoryMappedSegment *segment,
 184                             MemoryMappedSegmentData *seg_data,
 185                             MemoryMappingLayoutData *layout_data) {
 186   const char *lc = layout_data->current_load_cmd_addr;
 187   layout_data->current_load_cmd_addr += ((const load_command *)lc)->cmdsize;
 188   if (((const load_command *)lc)->cmd == kLCSegment) {
 189     const SegmentCommand* sc = (const SegmentCommand *)lc;
 190     uptr base_virt_addr, addr_mask;
 191     if (layout_data->current_image == kDyldImageIdx) {
 192       base_virt_addr = (uptr)get_dyld_hdr();
 193       // vmaddr is masked with 0xfffff because on macOS versions < 10.12,
 194       // it contains an absolute address rather than an offset for dyld.
 195       // To make matters even more complicated, this absolute address
 196       // isn't actually the absolute segment address, but the offset portion
 197       // of the address is accurate when combined with the dyld base address,
 198       // and the mask will give just this offset.
 199       addr_mask = 0xfffff;
 200     } else {
 201       base_virt_addr =
 202           (uptr)_dyld_get_image_vmaddr_slide(layout_data->current_image);
 203       addr_mask = ~0;
 204     }
 205
 206     segment->start = (sc->vmaddr & addr_mask) + base_virt_addr;
 207     segment->end = segment->start + sc->vmsize;
 208     // Most callers don't need section information, so only fill this struct
 209     // when required.
 210     if (seg_data) {
 211       seg_data->nsects = sc->nsects;
 212       seg_data->current_load_cmd_addr =
 213           (const char *)lc + sizeof(SegmentCommand);
 214       seg_data->lc_type = kLCSegment;
 215       seg_data->base_virt_addr = base_virt_addr;
 216       seg_data->addr_mask = addr_mask;
 217       internal_strncpy(seg_data->name, sc->segname,
 218                        ARRAY_SIZE(seg_data->name));
 219     }
 220
 221     // Return the initial protection.
 222     segment->protection = sc->initprot;
 223     segment->offset = (layout_data->current_filetype ==
 224                        /*MH_EXECUTE*/ 0x2)
 225                           ? sc->vmaddr
 226                           : sc->fileoff;
 227     if (segment->filename) {
 228       const char *src = (layout_data->current_image == kDyldImageIdx)
 229                             ? kDyldPath
 230                             : _dyld_get_image_name(layout_data->current_image);
 231       internal_strncpy(segment->filename, src, segment->filename_size);
 232     }
 233     segment->arch = layout_data->current_arch;
 234     internal_memcpy(segment->uuid, layout_data->current_uuid, kModuleUUIDSize);
 235     return true;
 236   }
 237   return false;
 238 }
 239
 240 ModuleArch ModuleArchFromCpuType(cpu_type_t cputype, cpu_subtype_t cpusubtype) {
 241   cpusubtype = cpusubtype & ~CPU_SUBTYPE_MASK;
 242   switch (cputype) {
 243     case CPU_TYPE_I386:
 244       return kModuleArchI386;
 245     case CPU_TYPE_X86_64:
 246       if (cpusubtype == CPU_SUBTYPE_X86_64_ALL) return kModuleArchX86_64;
 247       if (cpusubtype == CPU_SUBTYPE_X86_64_H) return kModuleArchX86_64H;
 248       CHECK(0 && "Invalid subtype of x86_64");
 249       return kModuleArchUnknown;
 250     case CPU_TYPE_ARM:
 251       if (cpusubtype == CPU_SUBTYPE_ARM_V6) return kModuleArchARMV6;
 252       if (cpusubtype == CPU_SUBTYPE_ARM_V7) return kModuleArchARMV7;
 253       if (cpusubtype == CPU_SUBTYPE_ARM_V7S) return kModuleArchARMV7S;
 254       if (cpusubtype == CPU_SUBTYPE_ARM_V7K) return kModuleArchARMV7K;
 255       CHECK(0 && "Invalid subtype of ARM");
 256       return kModuleArchUnknown;
 257     case CPU_TYPE_ARM64:
 258       return kModuleArchARM64;
 259     default:
 260       CHECK(0 && "Invalid CPU type");
 261       return kModuleArchUnknown;
 262   }
 263 }
 264
 265 static const load_command *NextCommand(const load_command *lc) {
 266   return (const load_command *)((const char *)lc + lc->cmdsize);
 267 }
 268
 269 static void FindUUID(const load_command *first_lc, u8 *uuid_output) {
 270   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
 271     if (lc->cmd != LC_UUID) continue;
 272
 273     const uuid_command *uuid_lc = (const uuid_command *)lc;
 274     const uint8_t *uuid = &uuid_lc->uuid[0];
 275     internal_memcpy(uuid_output, uuid, kModuleUUIDSize);
 276     return;
 277   }
 278 }
 279
 280 static bool IsModuleInstrumented(const load_command *first_lc) {
 281   for (const load_command *lc = first_lc; lc->cmd != 0; lc = NextCommand(lc)) {
 282     if (lc->cmd != LC_LOAD_DYLIB) continue;
 283
 284     const dylib_command *dylib_lc = (const dylib_command *)lc;
 285     uint32_t dylib_name_offset = dylib_lc->dylib.name.offset;
 286     const char *dylib_name = ((const char *)dylib_lc) + dylib_name_offset;
 287     dylib_name = StripModuleName(dylib_name);
 288     if (dylib_name != 0 && (internal_strstr(dylib_name, "libclang_rt."))) {
 289       return true;
 290     }
 291   }
 292   return false;
 293 }
 294
 295 bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
 296   for (; data_.current_image >= kDyldImageIdx; data_.current_image--) {
 297     const mach_header *hdr = (data_.current_image == kDyldImageIdx)
 298                                  ? get_dyld_hdr()
 299                                  : _dyld_get_image_header(data_.current_image);
 300     if (!hdr) continue;
 301     if (data_.current_load_cmd_count < 0) {
 302       // Set up for this image;
 303       data_.current_load_cmd_count = hdr->ncmds;
 304       data_.current_magic = hdr->magic;
 305       data_.current_filetype = hdr->filetype;
 306       data_.current_arch = ModuleArchFromCpuType(hdr->cputype, hdr->cpusubtype);
 307       switch (data_.current_magic) {
 308 #ifdef MH_MAGIC_64
 309         case MH_MAGIC_64: {
 310           data_.current_load_cmd_addr =
 311               (const char *)hdr + sizeof(mach_header_64);
 312           break;
 313         }
 314 #endif
 315         case MH_MAGIC: {
 316           data_.current_load_cmd_addr = (const char *)hdr + sizeof(mach_header);
 317           break;
 318         }
 319         default: {
 320           continue;
 321         }
 322       }
 323       FindUUID((const load_command *)data_.current_load_cmd_addr,
 324                data_.current_uuid);
 325       data_.current_instrumented = IsModuleInstrumented(
 326           (const load_command *)data_.current_load_cmd_addr);
 327     }
 328
 329     for (; data_.current_load_cmd_count >= 0; data_.current_load_cmd_count--) {
 330       switch (data_.current_magic) {
 331         // data_.current_magic may be only one of MH_MAGIC, MH_MAGIC_64.
 332 #ifdef MH_MAGIC_64
 333         case MH_MAGIC_64: {
 334           if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
 335                   segment, segment->data_, &data_))
 336             return true;
 337           break;
 338         }
 339 #endif
 340         case MH_MAGIC: {
 341           if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
 342                   segment, segment->data_, &data_))
 343             return true;
 344           break;
 345         }
 346       }
 347     }
 348     // If we get here, no more load_cmd's in this image talk about
 349     // segments.  Go on to the next image.
 350   }
 351   return false;
 352 }
 353
 354 void MemoryMappingLayout::DumpListOfModules(
 355     InternalMmapVectorNoCtor<LoadedModule> *modules) {
 356   Reset();
 357   InternalMmapVector<char> module_name(kMaxPathLength);
 358   MemoryMappedSegment segment(module_name.data(), module_name.size());
 359   MemoryMappedSegmentData data;
 360   segment.data_ = &data;
 361   while (Next(&segment)) {
 362     if (segment.filename[0] == '\0') continue;
 363     LoadedModule *cur_module = nullptr;
 364     if (!modules->empty() &&
 365         0 == internal_strcmp(segment.filename, modules->back().full_name())) {
 366       cur_module = &modules->back();
 367     } else {
 368       modules->push_back(LoadedModule());
 369       cur_module = &modules->back();
 370       cur_module->set(segment.filename, segment.start, segment.arch,
 371                       segment.uuid, data_.current_instrumented);
 372     }
 373     segment.AddAddressRanges(cur_module);
 374   }
 375 }
 376
 377 }  // namespace __sanitizer
 378
 379 #endif  // SANITIZER_MAC