/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This program verifies the integrity of the partitions after an A/B OTA
* update. It gets invoked by init, and will only perform the verification if
* it's the first boot post an A/B OTA update.
*
* It relies on dm-verity to capture any corruption on the partitions being
* verified. dm-verity must be in enforcing mode, so that it will reboot the
* device on dm-verity failures. When that happens, the bootloader should
* mark the slot as unbootable and stops trying. Other dm-verity modes (
* for example, veritymode=EIO) are not accepted and simply lead to a
* verification failure.
*
* The current slot will be marked as having booted successfully if the
* verifier reaches the end after the verification.
*
*/
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/parseint.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <cutils/properties.h>
#include <hardware/boot_control.h>
#define LOG_TAG "update_verifier"
#include <log/log.h>
constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
constexpr int BLOCKSIZE = 4096;
static bool read_blocks(const std::string& blk_device_prefix, const std::string& range_str) {
char slot_suffix[PROPERTY_VALUE_MAX];
property_get("ro.boot.slot_suffix", slot_suffix, "");
std::string blk_device = blk_device_prefix + std::string(slot_suffix);
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(blk_device.c_str(), O_RDONLY)));
if (fd.get() == -1) {
SLOGE("Error reading partition %s: %s\n", blk_device.c_str(), strerror(errno));
return false;
}
// For block range string, first integer 'count' equals 2 * total number of valid ranges,
// followed by 'count' number comma separated integers. Every two integers reprensent a
// block range with the first number included in range but second number not included.
// For example '4,64536,65343,74149,74150' represents: [64536,65343) and [74149,74150).
std::vector<std::string> ranges = android::base::Split(range_str, ",");
size_t range_count;
bool status = android::base::ParseUint(ranges[0].c_str(), &range_count);
if (!status || (range_count == 0) || (range_count % 2 != 0) ||
(range_count != ranges.size()-1)) {
SLOGE("Error in parsing range string.\n");
return false;
}
size_t blk_count = 0;
for (size_t i = 1; i < ranges.size(); i += 2) {
unsigned int range_start, range_end;
bool parse_status = android::base::ParseUint(ranges[i].c_str(), &range_start);
parse_status = parse_status && android::base::ParseUint(ranges[i+1].c_str(), &range_end);
if (!parse_status || range_start >= range_end) {
SLOGE("Invalid range pair %s, %s.\n", ranges[i].c_str(), ranges[i+1].c_str());
return false;
}
if (lseek64(fd.get(), static_cast<off64_t>(range_start) * BLOCKSIZE, SEEK_SET) == -1) {
SLOGE("lseek to %u failed: %s.\n", range_start, strerror(errno));
return false;
}
size_t size = (range_end - range_start) * BLOCKSIZE;
std::vector<uint8_t> buf(size);
if (!android::base::ReadFully(fd.get(), buf.data(), size)) {
SLOGE("Failed to read blocks %u to %u: %s.\n", range_start, range_end,
strerror(errno));
return false;
}
blk_count += (range_end - range_start);
}
SLOGI("Finished reading %zu blocks on %s.\n", blk_count, blk_device.c_str());
return true;
}
static bool verify_image(const std::string& care_map_name) {
android::base::unique_fd care_map_fd(TEMP_FAILURE_RETRY(open(care_map_name.c_str(), O_RDONLY)));
// If the device is flashed before the current boot, it may not have care_map.txt
// in /data/ota_package. To allow the device to continue booting in this situation,
// we should print a warning and skip the block verification.
if (care_map_fd.get() == -1) {
SLOGI("Warning: care map %s not found.\n", care_map_name.c_str());
return true;
}
// Care map file has four lines (two lines if vendor partition is not present):
// First line has the block device name, e.g./dev/block/.../by-name/system.
// Second line holds all ranges of blocks to verify.
// The next two lines have the same format but for vendor partition.
std::string file_content;
if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
SLOGE("Error reading care map contents to string.\n");
return false;
}
std::vector<std::string> lines;
lines = android::base::Split(android::base::Trim(file_content), "\n");
if (lines.size() != 2 && lines.size() != 4) {
SLOGE("Invalid lines in care_map: found %zu lines, expecting 2 or 4 lines.\n",
lines.size());
return false;
}
for (size_t i = 0; i < lines.size(); i += 2) {
if (!read_blocks(lines[i], lines[i+1])) {
return false;
}
}
return true;
}
int main(int argc, char** argv) {
for (int i = 1; i < argc; i++) {
SLOGI("Started with arg %d: %s\n", i, argv[i]);
}
const hw_module_t* hw_module;
if (hw_get_module("bootctrl", &hw_module) != 0) {
SLOGE("Error getting bootctrl module.\n");
return -1;
}
boot_control_module_t* module = reinterpret_cast<boot_control_module_t*>(
const_cast<hw_module_t*>(hw_module));
module->init(module);
unsigned current_slot = module->getCurrentSlot(module);
int is_successful= module->isSlotMarkedSuccessful(module, current_slot);
SLOGI("Booting slot %u: isSlotMarkedSuccessful=%d\n", current_slot, is_successful);
if (is_successful == 0) {
// The current slot has not booted successfully.
char verity_mode[PROPERTY_VALUE_MAX];
if (property_get("ro.boot.veritymode", verity_mode, "") == -1) {
SLOGE("Failed to get dm-verity mode");
return -1;
} else if (strcasecmp(verity_mode, "eio") == 0) {
// We shouldn't see verity in EIO mode if the current slot hasn't booted
// successfully before. Therefore, fail the verification when veritymode=eio.
SLOGE("Found dm-verity in EIO mode, skip verification.");
return -1;
} else if (strcmp(verity_mode, "enforcing") != 0) {
SLOGE("Unexpected dm-verity mode : %s, expecting enforcing.", verity_mode);
return -1;
} else if (!verify_image(CARE_MAP_FILE)) {
SLOGE("Failed to verify all blocks in care map file.\n");
return -1;
}
int ret = module->markBootSuccessful(module);
if (ret != 0) {
SLOGE("Error marking booted successfully: %s\n", strerror(-ret));
return -1;
}
SLOGI("Marked slot %u as booted successfully.\n", current_slot);
}
SLOGI("Leaving update_verifier.\n");
return 0;
}
