libsecurity_utilities/lib/dyldcache.cpp

   1 /*
   2  * Copyright (c) 2009 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 //
  25 // dyldcache - access layer to the DYLD Shared Library Cache file
  26 //
  27 #include "dyldcache.h"
  28
  29
  30 //
  31 // Table of supported architectures.
  32 // The cache file header has no direct architecture information, so we need to deduce it like this.
  33 //
  34 static const uint16_t bigEndian = 0x1200;
  35 static const uint16_t littleEndian = 0x0012;
  36
  37 const DYLDCache::ArchType DYLDCache::architectures[] = {
  38         { CPU_TYPE_X86_64, CPU_SUBTYPE_MULTIPLE,        "dyld_v1  x86_64", "x86_64", littleEndian },
  39         { CPU_TYPE_X86, CPU_SUBTYPE_MULTIPLE,           "dyld_v1    i386", "i386", littleEndian },
  40         { CPU_TYPE_POWERPC, CPU_SUBTYPE_MULTIPLE,       "dyld_v1     ppc", "rosetta", bigEndian },
  41         { CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V6,                     "dyld_v1   armv6", "armv6", littleEndian },
  42         { CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V7,                     "dyld_v1   armv7", "armv7", littleEndian },
  43         { 0 }
  44 };
  45
  46
  47 //
  48 // Architecture matching and lookup
  49 //
  50 std::string DYLDCache::pathFor(const Architecture &arch)
  51 {
  52         for (const ArchType *it = architectures; it->cpu; it++)
  53                 if (arch.matches(it->architecture()))
  54                         return it->path();
  55         UnixError::throwMe(ENOEXEC);
  56 }
  57
  58 const DYLDCache::ArchType *DYLDCache::matchArchitecture(const dyld_cache_header &header)
  59 {
  60         for (const ArchType *arch = architectures; arch->cpu; arch++)
  61                 if (!strcmp(header.magic, arch->magic))
  62                         return arch;
  63         return NULL;
  64 }
  65
  66
  67 //
  68 // Construction and teardown
  69 //
  70 DYLDCache::DYLDCache(const std::string &path)
  71 {
  72         this->open(path);
  73         mLength = this->fileSize();
  74         mBase = this->mmap(PROT_READ, mLength);
  75         mHeader = at<dyld_cache_header>(0);
  76
  77         if ((mArch = matchArchitecture(*mHeader)) == NULL)
  78                 UnixError::throwMe(ENOEXEC);
  79         mFlip = *((const uint8_t *)&mArch->order) != 0x12;
  80
  81         mSigStart = flip(mHeader->codeSignatureOffset);
  82         mSigLength = flip(mHeader->codeSignatureSize);
  83 }
  84
  85
  86 DYLDCache::~DYLDCache()
  87 {
  88         ::munmap((void *)mBase, mLength);
  89 }
  90
  91
  92 //
  93 // Preflight a file for file type
  94 //
  95 bool DYLDCache::validate(UnixPlusPlus::FileDesc &fd)
  96 {
  97         dyld_cache_header header;
  98         return fd.read(&header, sizeof(header), 0) == sizeof(header)
  99                 && matchArchitecture(header) != NULL;
 100 }
 101
 102
 103 //
 104 // Locate a mapping in the cache
 105 //
 106 DYLDCache::Mapping DYLDCache::mapping(unsigned ix) const
 107 {
 108         assert(ix < this->mappingCount());
 109         return Mapping(*this, flip(mHeader->mappingOffset) + ix * sizeof(shared_file_mapping_np));
 110 }
 111
 112
 113 //
 114 // Locate an image in the cache
 115 //
 116 DYLDCache::Image DYLDCache::image(unsigned ix) const
 117 {
 118         assert(ix < this->imageCount());
 119         return Image(*this, flip(mHeader->imagesOffset) + ix * sizeof(dyld_cache_image_info));
 120 }
 121
 122
 123
 124 DYLDCache::Mapping DYLDCache::findMap(uint64_t address) const
 125 {
 126         for (unsigned ix = 0; ix < mappingCount(); ix++) {
 127                 Mapping map = this->mapping(ix);
 128                 if (map.contains(address))
 129                         return map;
 130         }
 131         UnixError::throwMe(EINVAL);
 132 }
 133
 134 uint64_t DYLDCache::mapAddress(uint64_t address) const
 135 {
 136         Mapping map = this->findMap(address);
 137         return (address - map.address()) + map.offset();
 138 }