1 /*
2 * Copyright (C) 2015 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 /*
18 * This program verifies the integrity of the partitions after an A/B OTA
19 * update. It gets invoked by init, and will only perform the verification if
20 * it's the first boot post an A/B OTA update.
21 *
22 * It relies on dm-verity to capture any corruption on the partitions being
23 * verified. dm-verity must be in enforcing mode, so that it will reboot the
24 * device on dm-verity failures. When that happens, the bootloader should
25 * mark the slot as unbootable and stops trying. Other dm-verity modes (
26 * for example, veritymode=EIO) are not accepted and simply lead to a
27 * verification failure.
28 *
29 * The current slot will be marked as having booted successfully if the
30 * verifier reaches the end after the verification.
31 *
32 */
33
34 #include <errno.h>
35 #include <fcntl.h>
36 #include <stdio.h>
37 #include <string.h>
38
39 #include <string>
40 #include <vector>
41
42 #include <android-base/file.h>
43 #include <android-base/parseint.h>
44 #include <android-base/strings.h>
45 #include <android-base/unique_fd.h>
46 #include <cutils/properties.h>
47 #include <hardware/boot_control.h>
48 #define LOG_TAG "update_verifier"
49 #include <log/log.h>
50
51 constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
52 constexpr int BLOCKSIZE = 4096;
53
read_blocks(const std::string & blk_device_prefix,const std::string & range_str)54 static bool read_blocks(const std::string& blk_device_prefix, const std::string& range_str) {
55 char slot_suffix[PROPERTY_VALUE_MAX];
56 property_get("ro.boot.slot_suffix", slot_suffix, "");
57 std::string blk_device = blk_device_prefix + std::string(slot_suffix);
58 android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(blk_device.c_str(), O_RDONLY)));
59 if (fd.get() == -1) {
60 SLOGE("Error reading partition %s: %s\n", blk_device.c_str(), strerror(errno));
61 return false;
62 }
63
64 // For block range string, first integer 'count' equals 2 * total number of valid ranges,
65 // followed by 'count' number comma separated integers. Every two integers reprensent a
66 // block range with the first number included in range but second number not included.
67 // For example '4,64536,65343,74149,74150' represents: [64536,65343) and [74149,74150).
68 std::vector<std::string> ranges = android::base::Split(range_str, ",");
69 size_t range_count;
70 bool status = android::base::ParseUint(ranges[0].c_str(), &range_count);
71 if (!status || (range_count == 0) || (range_count % 2 != 0) ||
72 (range_count != ranges.size()-1)) {
73 SLOGE("Error in parsing range string.\n");
74 return false;
75 }
76
77 size_t blk_count = 0;
78 for (size_t i = 1; i < ranges.size(); i += 2) {
79 unsigned int range_start, range_end;
80 bool parse_status = android::base::ParseUint(ranges[i].c_str(), &range_start);
81 parse_status = parse_status && android::base::ParseUint(ranges[i+1].c_str(), &range_end);
82 if (!parse_status || range_start >= range_end) {
83 SLOGE("Invalid range pair %s, %s.\n", ranges[i].c_str(), ranges[i+1].c_str());
84 return false;
85 }
86
87 if (lseek64(fd.get(), static_cast<off64_t>(range_start) * BLOCKSIZE, SEEK_SET) == -1) {
88 SLOGE("lseek to %u failed: %s.\n", range_start, strerror(errno));
89 return false;
90 }
91
92 size_t size = (range_end - range_start) * BLOCKSIZE;
93 std::vector<uint8_t> buf(size);
94 if (!android::base::ReadFully(fd.get(), buf.data(), size)) {
95 SLOGE("Failed to read blocks %u to %u: %s.\n", range_start, range_end,
96 strerror(errno));
97 return false;
98 }
99 blk_count += (range_end - range_start);
100 }
101
102 SLOGI("Finished reading %zu blocks on %s.\n", blk_count, blk_device.c_str());
103 return true;
104 }
105
verify_image(const std::string & care_map_name)106 static bool verify_image(const std::string& care_map_name) {
107 android::base::unique_fd care_map_fd(TEMP_FAILURE_RETRY(open(care_map_name.c_str(), O_RDONLY)));
108 // If the device is flashed before the current boot, it may not have care_map.txt
109 // in /data/ota_package. To allow the device to continue booting in this situation,
110 // we should print a warning and skip the block verification.
111 if (care_map_fd.get() == -1) {
112 SLOGI("Warning: care map %s not found.\n", care_map_name.c_str());
113 return true;
114 }
115 // Care map file has four lines (two lines if vendor partition is not present):
116 // First line has the block device name, e.g./dev/block/.../by-name/system.
117 // Second line holds all ranges of blocks to verify.
118 // The next two lines have the same format but for vendor partition.
119 std::string file_content;
120 if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
121 SLOGE("Error reading care map contents to string.\n");
122 return false;
123 }
124
125 std::vector<std::string> lines;
126 lines = android::base::Split(android::base::Trim(file_content), "\n");
127 if (lines.size() != 2 && lines.size() != 4) {
128 SLOGE("Invalid lines in care_map: found %zu lines, expecting 2 or 4 lines.\n",
129 lines.size());
130 return false;
131 }
132
133 for (size_t i = 0; i < lines.size(); i += 2) {
134 if (!read_blocks(lines[i], lines[i+1])) {
135 return false;
136 }
137 }
138
139 return true;
140 }
141
main(int argc,char ** argv)142 int main(int argc, char** argv) {
143 for (int i = 1; i < argc; i++) {
144 SLOGI("Started with arg %d: %s\n", i, argv[i]);
145 }
146
147 const hw_module_t* hw_module;
148 if (hw_get_module("bootctrl", &hw_module) != 0) {
149 SLOGE("Error getting bootctrl module.\n");
150 return -1;
151 }
152
153 boot_control_module_t* module = reinterpret_cast<boot_control_module_t*>(
154 const_cast<hw_module_t*>(hw_module));
155 module->init(module);
156
157 unsigned current_slot = module->getCurrentSlot(module);
158 int is_successful= module->isSlotMarkedSuccessful(module, current_slot);
159 SLOGI("Booting slot %u: isSlotMarkedSuccessful=%d\n", current_slot, is_successful);
160 if (is_successful == 0) {
161 // The current slot has not booted successfully.
162 char verity_mode[PROPERTY_VALUE_MAX];
163 if (property_get("ro.boot.veritymode", verity_mode, "") == -1) {
164 SLOGE("Failed to get dm-verity mode");
165 return -1;
166 } else if (strcasecmp(verity_mode, "eio") == 0) {
167 // We shouldn't see verity in EIO mode if the current slot hasn't booted
168 // successfully before. Therefore, fail the verification when veritymode=eio.
169 SLOGE("Found dm-verity in EIO mode, skip verification.");
170 return -1;
171 } else if (strcmp(verity_mode, "enforcing") != 0) {
172 SLOGE("Unexpected dm-verity mode : %s, expecting enforcing.", verity_mode);
173 return -1;
174 } else if (!verify_image(CARE_MAP_FILE)) {
175 SLOGE("Failed to verify all blocks in care map file.\n");
176 return -1;
177 }
178
179 int ret = module->markBootSuccessful(module);
180 if (ret != 0) {
181 SLOGE("Error marking booted successfully: %s\n", strerror(-ret));
182 return -1;
183 }
184 SLOGI("Marked slot %u as booted successfully.\n", current_slot);
185 }
186
187 SLOGI("Leaving update_verifier.\n");
188 return 0;
189 }
190