1 /* 2 ** 3 ** Copyright 2016, The Android Open Source Project 4 ** 5 ** Licensed under the Apache License, Version 2.0 (the "License"); 6 ** you may not use this file except in compliance with the License. 7 ** You may obtain a copy of the License at 8 ** 9 ** http://www.apache.org/licenses/LICENSE-2.0 10 ** 11 ** Unless required by applicable law or agreed to in writing, software 12 ** distributed under the License is distributed on an "AS IS" BASIS, 13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 ** See the License for the specific language governing permissions and 15 ** limitations under the License. 16 */ 17 18 #include "read_apk.h" 19 20 #include <errno.h> 21 #include <stdio.h> 22 #include <string.h> 23 #include <sys/stat.h> 24 #include <sys/types.h> 25 #include <unistd.h> 26 27 #include <memory> 28 29 #include <android-base/file.h> 30 #include <android-base/logging.h> 31 #include <ziparchive/zip_archive.h> 32 #include "read_elf.h" 33 #include "utils.h" 34 35 std::map<ApkInspector::ApkOffset, std::unique_ptr<EmbeddedElf>> ApkInspector::embedded_elf_cache_; 36 37 EmbeddedElf* ApkInspector::FindElfInApkByOffset(const std::string& apk_path, uint64_t file_offset) { 38 // Already in cache? 39 ApkOffset ami(apk_path, file_offset); 40 auto it = embedded_elf_cache_.find(ami); 41 if (it != embedded_elf_cache_.end()) { 42 return it->second.get(); 43 } 44 std::unique_ptr<EmbeddedElf> elf = FindElfInApkByOffsetWithoutCache(apk_path, file_offset); 45 EmbeddedElf* result = elf.get(); 46 embedded_elf_cache_[ami] = std::move(elf); 47 return result; 48 } 49 50 std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByOffsetWithoutCache(const std::string& apk_path, 51 uint64_t file_offset) { 52 // Crack open the apk(zip) file and take a look. 53 if (!IsValidApkPath(apk_path)) { 54 return nullptr; 55 } 56 57 FileHelper fhelper = FileHelper::OpenReadOnly(apk_path); 58 if (!fhelper) { 59 return nullptr; 60 } 61 62 ArchiveHelper ahelper(fhelper.fd(), apk_path); 63 if (!ahelper) { 64 return nullptr; 65 } 66 ZipArchiveHandle &handle = ahelper.archive_handle(); 67 68 // Iterate through the zip file. Look for a zip entry corresponding 69 // to an uncompressed blob whose range intersects with the mmap 70 // offset we're interested in. 71 void* iteration_cookie; 72 if (StartIteration(handle, &iteration_cookie, nullptr, nullptr) < 0) { 73 return nullptr; 74 } 75 ZipEntry zentry; 76 ZipString zname; 77 bool found = false; 78 int zrc; 79 while ((zrc = Next(iteration_cookie, &zentry, &zname)) == 0) { 80 if (zentry.method == kCompressStored && 81 file_offset >= static_cast<uint64_t>(zentry.offset) && 82 file_offset < static_cast<uint64_t>(zentry.offset + zentry.uncompressed_length)) { 83 // Found. 84 found = true; 85 break; 86 } 87 } 88 EndIteration(iteration_cookie); 89 if (!found) { 90 return nullptr; 91 } 92 93 // We found something in the zip file at the right spot. Is it an ELF? 94 if (lseek(fhelper.fd(), zentry.offset, SEEK_SET) != zentry.offset) { 95 PLOG(ERROR) << "lseek() failed in " << apk_path << " offset " << zentry.offset; 96 return nullptr; 97 } 98 std::string entry_name; 99 entry_name.resize(zname.name_length,'\0'); 100 memcpy(&entry_name[0], zname.name, zname.name_length); 101 ElfStatus result = IsValidElfFile(fhelper.fd()); 102 if (result != ElfStatus::NO_ERROR) { 103 LOG(ERROR) << "problems reading ELF from " << apk_path << " entry '" 104 << entry_name << "': " << result; 105 return nullptr; 106 } 107 108 // Elf found: add EmbeddedElf to vector, update cache. 109 return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, entry_name, zentry.offset, 110 zentry.uncompressed_length)); 111 } 112 113 std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByName(const std::string& apk_path, 114 const std::string& elf_filename) { 115 if (!IsValidApkPath(apk_path)) { 116 return nullptr; 117 } 118 FileHelper fhelper = FileHelper::OpenReadOnly(apk_path); 119 if (!fhelper) { 120 return nullptr; 121 } 122 ArchiveHelper ahelper(fhelper.fd(), apk_path); 123 if (!ahelper) { 124 return nullptr; 125 } 126 ZipArchiveHandle& handle = ahelper.archive_handle(); 127 ZipEntry zentry; 128 int32_t rc = FindEntry(handle, ZipString(elf_filename.c_str()), &zentry); 129 if (rc != 0) { 130 LOG(ERROR) << "failed to find " << elf_filename << " in " << apk_path 131 << ": " << ErrorCodeString(rc); 132 return nullptr; 133 } 134 if (zentry.method != kCompressStored || zentry.compressed_length != zentry.uncompressed_length) { 135 LOG(ERROR) << "shared library " << elf_filename << " in " << apk_path << " is compressed"; 136 return nullptr; 137 } 138 return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, elf_filename, zentry.offset, 139 zentry.uncompressed_length)); 140 } 141 142 bool IsValidApkPath(const std::string& apk_path) { 143 static const char zip_preamble[] = {0x50, 0x4b, 0x03, 0x04 }; 144 if (!IsRegularFile(apk_path)) { 145 return false; 146 } 147 std::string mode = std::string("rb") + CLOSE_ON_EXEC_MODE; 148 FILE* fp = fopen(apk_path.c_str(), mode.c_str()); 149 if (fp == nullptr) { 150 return false; 151 } 152 char buf[4]; 153 if (fread(buf, 4, 1, fp) != 1) { 154 fclose(fp); 155 return false; 156 } 157 fclose(fp); 158 return memcmp(buf, zip_preamble, 4) == 0; 159 } 160 161 // Refer file in apk in compliance with http://developer.android.com/reference/java/net/JarURLConnection.html. 162 std::string GetUrlInApk(const std::string& apk_path, const std::string& elf_filename) { 163 return apk_path + "!/" + elf_filename; 164 } 165 166 std::tuple<bool, std::string, std::string> SplitUrlInApk(const std::string& path) { 167 size_t pos = path.find("!/"); 168 if (pos == std::string::npos) { 169 return std::make_tuple(false, "", ""); 170 } 171 return std::make_tuple(true, path.substr(0, pos), path.substr(pos + 2)); 172 } 173 174 ElfStatus GetBuildIdFromApkFile(const std::string& apk_path, const std::string& elf_filename, 175 BuildId* build_id) { 176 std::unique_ptr<EmbeddedElf> ee = ApkInspector::FindElfInApkByName(apk_path, elf_filename); 177 if (ee == nullptr) { 178 return ElfStatus::FILE_NOT_FOUND; 179 } 180 return GetBuildIdFromEmbeddedElfFile(apk_path, ee->entry_offset(), ee->entry_size(), build_id); 181 } 182 183 ElfStatus ParseSymbolsFromApkFile(const std::string& apk_path, const std::string& elf_filename, 184 const BuildId& expected_build_id, 185 const std::function<void(const ElfFileSymbol&)>& callback) { 186 std::unique_ptr<EmbeddedElf> ee = ApkInspector::FindElfInApkByName(apk_path, elf_filename); 187 if (ee == nullptr) { 188 return ElfStatus::FILE_NOT_FOUND; 189 } 190 return ParseSymbolsFromEmbeddedElfFile(apk_path, ee->entry_offset(), ee->entry_size(), 191 expected_build_id, callback); 192 } 193
