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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 <android-base/strings.h>
32 #include <ziparchive/zip_archive.h>
33 #include "read_elf.h"
34 #include "utils.h"
35 
36 std::unordered_map<std::string, ApkInspector::ApkNode> ApkInspector::embedded_elf_cache_;
37 
FindElfInApkByOffset(const std::string & apk_path,uint64_t file_offset)38 EmbeddedElf* ApkInspector::FindElfInApkByOffset(const std::string& apk_path, uint64_t file_offset) {
39   // Already in cache?
40   ApkNode& node = embedded_elf_cache_[apk_path];
41   auto it = node.offset_map.find(file_offset);
42   if (it != node.offset_map.end()) {
43     return it->second.get();
44   }
45   std::unique_ptr<EmbeddedElf> elf = FindElfInApkByOffsetWithoutCache(apk_path, file_offset);
46   EmbeddedElf* result = elf.get();
47   node.offset_map[file_offset] = std::move(elf);
48   if (result != nullptr) {
49     node.name_map[result->entry_name()] = result;
50   }
51   return result;
52 }
53 
FindElfInApkByName(const std::string & apk_path,const std::string & entry_name)54 EmbeddedElf* ApkInspector::FindElfInApkByName(const std::string& apk_path,
55                                               const std::string& entry_name) {
56   ApkNode& node = embedded_elf_cache_[apk_path];
57   auto it = node.name_map.find(entry_name);
58   if (it != node.name_map.end()) {
59     return it->second;
60   }
61   std::unique_ptr<EmbeddedElf> elf = FindElfInApkByNameWithoutCache(apk_path, entry_name);
62   EmbeddedElf* result = elf.get();
63   node.name_map[entry_name] = result;
64   if (result != nullptr) {
65     node.offset_map[result->entry_offset()] = std::move(elf);
66   }
67   return result;
68 }
69 
FindElfInApkByOffsetWithoutCache(const std::string & apk_path,uint64_t file_offset)70 std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByOffsetWithoutCache(
71     const std::string& apk_path, uint64_t file_offset) {
72   std::unique_ptr<ArchiveHelper> ahelper = ArchiveHelper::CreateInstance(apk_path);
73   if (!ahelper) {
74     return nullptr;
75   }
76 
77   // Iterate through the zip file. Look for a zip entry corresponding
78   // to an uncompressed blob whose range intersects with the mmap
79   // offset we're interested in.
80   bool found = false;
81   ZipEntry found_entry;
82   std::string found_entry_name;
83   bool result = ahelper->IterateEntries([&](ZipEntry& entry, const std::string& name) {
84     if (entry.method == kCompressStored &&
85         file_offset >= static_cast<uint64_t>(entry.offset) &&
86         file_offset < static_cast<uint64_t>(entry.offset) + entry.uncompressed_length) {
87       found = true;
88       found_entry = entry;
89       found_entry_name = name;
90       return false;
91     }
92     return true;
93   });
94   if (!result || !found) {
95     return nullptr;
96   }
97 
98   // We found something in the zip file at the right spot. Is it an ELF?
99   if (lseek(ahelper->GetFd(), found_entry.offset, SEEK_SET) != found_entry.offset) {
100     PLOG(ERROR) << "lseek() failed in " << apk_path << " offset " << found_entry.offset;
101     return nullptr;
102   }
103   if (IsValidElfFile(ahelper->GetFd()) != ElfStatus::NO_ERROR) {
104     // Omit files that are not ELF files.
105     return nullptr;
106   }
107   return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, found_entry_name,
108                                                       found_entry.offset,
109                                                       found_entry.uncompressed_length));
110 }
111 
FindElfInApkByNameWithoutCache(const std::string & apk_path,const std::string & entry_name)112 std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByNameWithoutCache(
113     const std::string& apk_path, const std::string& entry_name) {
114   std::unique_ptr<ArchiveHelper> ahelper = ArchiveHelper::CreateInstance(apk_path);
115   if (!ahelper) {
116     return nullptr;
117   }
118   ZipEntry zentry;
119   if (!ahelper->FindEntry(entry_name, &zentry)) {
120     return nullptr;
121   }
122   if (zentry.method != kCompressStored || zentry.compressed_length != zentry.uncompressed_length) {
123     return nullptr;
124   }
125   return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, entry_name, zentry.offset,
126                                                       zentry.uncompressed_length));
127 }
128 
129 // Refer file in apk in compliance with http://developer.android.com/reference/java/net/JarURLConnection.html.
GetUrlInApk(const std::string & apk_path,const std::string & elf_filename)130 std::string GetUrlInApk(const std::string& apk_path, const std::string& elf_filename) {
131   return apk_path + "!/" + elf_filename;
132 }
133 
SplitUrlInApk(const std::string & path)134 std::tuple<bool, std::string, std::string> SplitUrlInApk(const std::string& path) {
135   size_t pos = path.find("!/");
136   if (pos == std::string::npos) {
137     return std::make_tuple(false, "", "");
138   }
139   return std::make_tuple(true, path.substr(0, pos), path.substr(pos + 2));
140 }
141 
142 // Parse path like "[anon:dalvik-classes.dex extracted in memory from /..base.apk] (deleted)",
143 // or "/dev/ashmem/dalvik-classes.dex extracted in memory from /..base.apk (deleted)" on Android P.
ParseExtractedInMemoryPath(const std::string & path,std::string * zip_path,std::string * entry_name)144 bool ParseExtractedInMemoryPath(const std::string& path, std::string* zip_path,
145                                 std::string* entry_name) {
146   const char* prefixes[2] = {"[anon:dalvik-", "/dev/ashmem/dalvik-"};
147   const char* key = " extracted in memory from ";
148   size_t pos = path.find(key);
149   if (pos != std::string::npos) {
150     for (const char* prefix : prefixes) {
151       if (android::base::StartsWith(path, prefix)) {
152         size_t entry_name_start = strlen(prefix);
153         size_t entry_name_end = pos;
154         size_t zip_path_start = pos + strlen(key);
155         size_t zip_path_end = path.find_first_of(" ]", zip_path_start);
156         if (zip_path_end == std::string::npos) {
157           zip_path_end = path.size();
158         }
159         if (entry_name_start < entry_name_end && zip_path_start < zip_path_end) {
160           *entry_name = path.substr(entry_name_start, entry_name_end - entry_name_start);
161           *zip_path = path.substr(zip_path_start, zip_path_end - zip_path_start);
162           size_t multidex_separator_pos = zip_path->find('!');
163           if (multidex_separator_pos != std::string::npos) {
164             zip_path->resize(multidex_separator_pos);
165           }
166           return true;
167         }
168       }
169     }
170   }
171   return false;
172 }
173