1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "otautil/SysUtil.h"
18
19 #include <errno.h> // TEMP_FAILURE_RETRY
20 #include <fcntl.h>
21 #include <stdint.h> // SIZE_MAX
22 #include <sys/mman.h>
23 #include <sys/stat.h>
24 #include <sys/types.h>
25
26 #include <string>
27 #include <vector>
28
29 #include <android-base/file.h>
30 #include <android-base/logging.h>
31 #include <android-base/strings.h>
32 #include <android-base/unique_fd.h>
33
MapFD(int fd)34 bool MemMapping::MapFD(int fd) {
35 struct stat sb;
36 if (fstat(fd, &sb) == -1) {
37 PLOG(ERROR) << "fstat(" << fd << ") failed";
38 return false;
39 }
40
41 void* memPtr = mmap(nullptr, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
42 if (memPtr == MAP_FAILED) {
43 PLOG(ERROR) << "mmap(" << sb.st_size << ", R, PRIVATE, " << fd << ", 0) failed";
44 return false;
45 }
46
47 addr = static_cast<unsigned char*>(memPtr);
48 length = sb.st_size;
49 ranges_.clear();
50 ranges_.emplace_back(MappedRange{ memPtr, static_cast<size_t>(sb.st_size) });
51
52 return true;
53 }
54
55 // A "block map" which looks like this (from uncrypt/uncrypt.cpp):
56 //
57 // /dev/block/platform/msm_sdcc.1/by-name/userdata # block device
58 // 49652 4096 # file size in bytes, block size
59 // 3 # count of block ranges
60 // 1000 1008 # block range 0
61 // 2100 2102 # ... block range 1
62 // 30 33 # ... block range 2
63 //
64 // Each block range represents a half-open interval; the line "30 33" reprents the blocks
65 // [30, 31, 32].
MapBlockFile(const std::string & filename)66 bool MemMapping::MapBlockFile(const std::string& filename) {
67 std::string content;
68 if (!android::base::ReadFileToString(filename, &content)) {
69 PLOG(ERROR) << "Failed to read " << filename;
70 return false;
71 }
72
73 std::vector<std::string> lines = android::base::Split(android::base::Trim(content), "\n");
74 if (lines.size() < 4) {
75 LOG(ERROR) << "Block map file is too short: " << lines.size();
76 return false;
77 }
78
79 size_t size;
80 size_t blksize;
81 if (sscanf(lines[1].c_str(), "%zu %zu", &size, &blksize) != 2) {
82 LOG(ERROR) << "Failed to parse file size and block size: " << lines[1];
83 return false;
84 }
85
86 size_t range_count;
87 if (sscanf(lines[2].c_str(), "%zu", &range_count) != 1) {
88 LOG(ERROR) << "Failed to parse block map header: " << lines[2];
89 return false;
90 }
91
92 size_t blocks;
93 if (blksize != 0) {
94 blocks = ((size - 1) / blksize) + 1;
95 }
96 if (size == 0 || blksize == 0 || blocks > SIZE_MAX / blksize || range_count == 0 ||
97 lines.size() != 3 + range_count) {
98 LOG(ERROR) << "Invalid data in block map file: size " << size << ", blksize " << blksize
99 << ", range_count " << range_count << ", lines " << lines.size();
100 return false;
101 }
102
103 // Reserve enough contiguous address space for the whole file.
104 void* reserve = mmap(nullptr, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
105 if (reserve == MAP_FAILED) {
106 PLOG(ERROR) << "failed to reserve address space";
107 return false;
108 }
109
110 const std::string& block_dev = lines[0];
111 android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(block_dev.c_str(), O_RDONLY)));
112 if (fd == -1) {
113 PLOG(ERROR) << "failed to open block device " << block_dev;
114 munmap(reserve, blocks * blksize);
115 return false;
116 }
117
118 ranges_.clear();
119
120 unsigned char* next = static_cast<unsigned char*>(reserve);
121 size_t remaining_size = blocks * blksize;
122 bool success = true;
123 for (size_t i = 0; i < range_count; ++i) {
124 const std::string& line = lines[i + 3];
125
126 size_t start, end;
127 if (sscanf(line.c_str(), "%zu %zu\n", &start, &end) != 2) {
128 LOG(ERROR) << "failed to parse range " << i << ": " << line;
129 success = false;
130 break;
131 }
132 size_t range_size = (end - start) * blksize;
133 if (end <= start || (end - start) > SIZE_MAX / blksize || range_size > remaining_size) {
134 LOG(ERROR) << "Invalid range: " << start << " " << end;
135 success = false;
136 break;
137 }
138
139 void* range_start = mmap(next, range_size, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd,
140 static_cast<off_t>(start) * blksize);
141 if (range_start == MAP_FAILED) {
142 PLOG(ERROR) << "failed to map range " << i << ": " << line;
143 success = false;
144 break;
145 }
146 ranges_.emplace_back(MappedRange{ range_start, range_size });
147
148 next += range_size;
149 remaining_size -= range_size;
150 }
151 if (success && remaining_size != 0) {
152 LOG(ERROR) << "Invalid ranges: remaining_size " << remaining_size;
153 success = false;
154 }
155 if (!success) {
156 munmap(reserve, blocks * blksize);
157 return false;
158 }
159
160 addr = static_cast<unsigned char*>(reserve);
161 length = size;
162
163 LOG(INFO) << "mmapped " << range_count << " ranges";
164
165 return true;
166 }
167
MapFile(const std::string & fn)168 bool MemMapping::MapFile(const std::string& fn) {
169 if (fn.empty()) {
170 LOG(ERROR) << "Empty filename";
171 return false;
172 }
173
174 if (fn[0] == '@') {
175 // Block map file "@/cache/recovery/block.map".
176 if (!MapBlockFile(fn.substr(1))) {
177 LOG(ERROR) << "Map of '" << fn << "' failed";
178 return false;
179 }
180 } else {
181 // This is a regular file.
182 android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(fn.c_str(), O_RDONLY)));
183 if (fd == -1) {
184 PLOG(ERROR) << "Unable to open '" << fn << "'";
185 return false;
186 }
187
188 if (!MapFD(fd)) {
189 LOG(ERROR) << "Map of '" << fn << "' failed";
190 return false;
191 }
192 }
193 return true;
194 }
195
~MemMapping()196 MemMapping::~MemMapping() {
197 for (const auto& range : ranges_) {
198 if (munmap(range.addr, range.length) == -1) {
199 PLOG(ERROR) << "Failed to munmap(" << range.addr << ", " << range.length << ")";
200 }
201 };
202 ranges_.clear();
203 }
204