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 
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 
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 
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 (IsValidElfFile(ahelper->GetFd(), found_entry.offset) != ElfStatus::NO_ERROR) {
100     // Omit files that are not ELF files.
101     return nullptr;
102   }
103   return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, found_entry_name,
104                                                       found_entry.offset,
105                                                       found_entry.uncompressed_length));
106 }
107 
108 std::unique_ptr<EmbeddedElf> ApkInspector::FindElfInApkByNameWithoutCache(
109     const std::string& apk_path, const std::string& entry_name) {
110   std::unique_ptr<ArchiveHelper> ahelper = ArchiveHelper::CreateInstance(apk_path);
111   if (!ahelper) {
112     return nullptr;
113   }
114   ZipEntry zentry;
115   if (!ahelper->FindEntry(entry_name, &zentry)) {
116     return nullptr;
117   }
118   if (zentry.method != kCompressStored || zentry.compressed_length != zentry.uncompressed_length) {
119     return nullptr;
120   }
121   return std::unique_ptr<EmbeddedElf>(new EmbeddedElf(apk_path, entry_name, zentry.offset,
122                                                       zentry.uncompressed_length));
123 }
124 
125 // Refer file in apk in compliance with http://developer.android.com/reference/java/net/JarURLConnection.html.
126 std::string GetUrlInApk(const std::string& apk_path, const std::string& elf_filename) {
127   return apk_path + "!/" + elf_filename;
128 }
129 
130 std::tuple<bool, std::string, std::string> SplitUrlInApk(const std::string& path) {
131   size_t pos = path.find("!/");
132   if (pos == std::string::npos) {
133     return std::make_tuple(false, "", "");
134   }
135   return std::make_tuple(true, path.substr(0, pos), path.substr(pos + 2));
136 }
137 
138 // Parse path like "[anon:dalvik-classes.dex extracted in memory from /..base.apk] (deleted)",
139 // or "/dev/ashmem/dalvik-classes.dex extracted in memory from /..base.apk (deleted)" on Android P.
140 bool ParseExtractedInMemoryPath(const std::string& path, std::string* zip_path,
141                                 std::string* entry_name) {
142   const char* prefixes[2] = {"[anon:dalvik-", "/dev/ashmem/dalvik-"};
143   const char* key = " extracted in memory from ";
144   size_t pos = path.find(key);
145   if (pos != std::string::npos) {
146     for (const char* prefix : prefixes) {
147       if (android::base::StartsWith(path, prefix)) {
148         size_t entry_name_start = strlen(prefix);
149         size_t entry_name_end = pos;
150         size_t zip_path_start = pos + strlen(key);
151         size_t zip_path_end = path.find_first_of(" ]", zip_path_start);
152         if (zip_path_end == std::string::npos) {
153           zip_path_end = path.size();
154         }
155         if (entry_name_start < entry_name_end && zip_path_start < zip_path_end) {
156           *entry_name = path.substr(entry_name_start, entry_name_end - entry_name_start);
157           *zip_path = path.substr(zip_path_start, zip_path_end - zip_path_start);
158           size_t multidex_separator_pos = zip_path->find('!');
159           if (multidex_separator_pos != std::string::npos) {
160             zip_path->resize(multidex_separator_pos);
161           }
162           return true;
163         }
164       }
165     }
166   }
167   return false;
168 }
169