update_verifier/update_verifier.cpp - android_bootable_recovery - Gitiles

 /*
  * 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.
  */

 /*
  * update_verifier 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
  * (https://source.android.com/devices/tech/ota/ab/#after_reboot).
  *
  * update_verifier relies on device-mapper-verity (dm-verity) to capture any corruption on the
  * partitions being verified (https://source.android.com/security/verifiedboot). The verification
  * will be skipped, if dm-verity is not enabled on the device.
  *
  * Upon detecting verification failures, the device will be rebooted, although the trigger of the
  * reboot depends on the dm-verity mode.
  *   enforcing mode: dm-verity reboots the device
  *   eio mode: dm-verity fails the read and update_verifier reboots the device
  *   other mode: not supported and update_verifier reboots the device
  *
  * All these reboots prevent the device from booting into a known corrupt state. If the device
  * continuously fails to boot into the new slot, the bootloader should mark the slot as unbootable
  * and trigger a fallback to the old slot.
  *
  * The current slot will be marked as having booted successfully if the verifier reaches the end
  * after the verification.
  */

 #include "update_verifier/update_verifier.h"

 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>

 #include <algorithm>
 #include <future>
 #include <string>
 #include <vector>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
 #include <android/hardware/boot/1.0/IBootControl.h>
 #include <cutils/android_reboot.h>

 #include "care_map.pb.h"
 #include "otautil/rangeset.h"

 using android::sp;
 using android::hardware::boot::V1_0::IBootControl;
 using android::hardware::boot::V1_0::BoolResult;
 using android::hardware::boot::V1_0::CommandResult;

 // Find directories in format of "/sys/block/dm-X".
 static int dm_name_filter(const dirent* de) {
   if (android::base::StartsWith(de->d_name, "dm-")) {
     return 1;
   }
   return 0;
 }

 static bool read_blocks(const std::string& partition, const std::string& range_str) {
   if (partition != "system" && partition != "vendor" && partition != "product") {
     LOG(ERROR) << "Invalid partition name \"" << partition << "\"";
     return false;
   }
   // Iterate the content of "/sys/block/dm-X/dm/name". If it matches one of "system", "vendor" or
   // "product", then dm-X is a dm-wrapped device for that target. We will later read all the
   // ("cared") blocks from "/dev/block/dm-X" to ensure the target partition's integrity.
   static constexpr auto DM_PATH_PREFIX = "/sys/block/";
   dirent** namelist;
   int n = scandir(DM_PATH_PREFIX, &namelist, dm_name_filter, alphasort);
   if (n == -1) {
     PLOG(ERROR) << "Failed to scan dir " << DM_PATH_PREFIX;
     return false;
   }
   if (n == 0) {
     LOG(ERROR) << "dm block device not found for " << partition;
     return false;
   }

   static constexpr auto DM_PATH_SUFFIX = "/dm/name";
   static constexpr auto DEV_PATH = "/dev/block/";
   std::string dm_block_device;
   while (n--) {
     std::string path = DM_PATH_PREFIX + std::string(namelist[n]->d_name) + DM_PATH_SUFFIX;
     std::string content;
     if (!android::base::ReadFileToString(path, &content)) {
       PLOG(WARNING) << "Failed to read " << path;
     } else {
       std::string dm_block_name = android::base::Trim(content);
       // AVB is using 'vroot' for the root block device but we're expecting 'system'.
       if (dm_block_name == "vroot") {
         dm_block_name = "system";
       }
       if (dm_block_name == partition) {
         dm_block_device = DEV_PATH + std::string(namelist[n]->d_name);
         while (n--) {
           free(namelist[n]);
         }
         break;
       }
     }
     free(namelist[n]);
   }
   free(namelist);

   if (dm_block_device.empty()) {
     LOG(ERROR) << "Failed to find dm block device for " << partition;
     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).
   RangeSet ranges = RangeSet::Parse(range_str);
   if (!ranges) {
     LOG(ERROR) << "Error parsing RangeSet string " << range_str;
     return false;
   }

   // RangeSet::Split() splits the ranges into multiple groups with same number of blocks (except for
   // the last group).
   size_t thread_num = std::thread::hardware_concurrency() ?: 4;
   std::vector<RangeSet> groups = ranges.Split(thread_num);

   std::vector<std::future<bool>> threads;
   for (const auto& group : groups) {
     auto thread_func = [&group, &dm_block_device, &partition]() {
       android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(dm_block_device.c_str(), O_RDONLY)));
       if (fd.get() == -1) {
         PLOG(ERROR) << "Error reading " << dm_block_device << " for partition " << partition;
         return false;
       }

       static constexpr size_t kBlockSize = 4096;
       std::vector<uint8_t> buf(1024 * kBlockSize);

       size_t block_count = 0;
       for (const auto& range : group) {
         size_t range_start = range.first;
         size_t range_end = range.second;
         if (lseek64(fd.get(), static_cast<off64_t>(range_start) * kBlockSize, SEEK_SET) == -1) {
           PLOG(ERROR) << "lseek to " << range_start << " failed";
           return false;
         }

         size_t remain = (range_end - range_start) * kBlockSize;
         while (remain > 0) {
           size_t to_read = std::min(remain, 1024 * kBlockSize);
           if (!android::base::ReadFully(fd.get(), buf.data(), to_read)) {
             PLOG(ERROR) << "Failed to read blocks " << range_start << " to " << range_end;
             return false;
           }
           remain -= to_read;
         }
         block_count += (range_end - range_start);
       }
       LOG(INFO) << "Finished reading " << block_count << " blocks on " << dm_block_device;
       return true;
     };

     threads.emplace_back(std::async(std::launch::async, thread_func));
   }

   bool ret = true;
   for (auto& t : threads) {
     ret = t.get() && ret;
   }
   LOG(INFO) << "Finished reading blocks on " << dm_block_device << " with " << thread_num
             << " threads.";
   return ret;
 }

 static bool process_care_map_plain_text(const std::string& care_map_contents) {
   // care_map file has up to six lines, where every two lines make a pair. Within each pair, the
   // first line has the partition name (e.g. "system"), while the second line holds the ranges of
   // all the blocks to verify.
   std::vector<std::string> lines =
       android::base::Split(android::base::Trim(care_map_contents), "\n");
   if (lines.size() != 2 && lines.size() != 4 && lines.size() != 6) {
     LOG(ERROR) << "Invalid lines in care_map: found " << lines.size()
                << " lines, expecting 2 or 4 or 6 lines.";
     return false;
   }

   for (size_t i = 0; i < lines.size(); i += 2) {
     // We're seeing an N care_map.txt. Skip the verification since it's not compatible with O
     // update_verifier (the last few metadata blocks can't be read via device mapper).
     if (android::base::StartsWith(lines[i], "/dev/block/")) {
       LOG(WARNING) << "Found legacy care_map.txt; skipped.";
       return true;
     }
     if (!read_blocks(lines[i], lines[i+1])) {
       return false;
     }
   }

   return true;
 }

 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) {
     PLOG(WARNING) << "Failed to open " << care_map_name;
     return true;
   }

   std::string file_content;
   if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
     PLOG(ERROR) << "Failed to read " << care_map_name;
     return false;
   }

   if (file_content.empty()) {
     LOG(ERROR) << "Unexpected empty care map";
     return false;
   }

   UpdateVerifier::CareMap care_map;
   // Falls back to use the plain text version if we cannot parse the file as protobuf message.
   if (!care_map.ParseFromString(file_content)) {
     return process_care_map_plain_text(file_content);
   }

   for (const auto& partition : care_map.partitions()) {
     if (partition.name().empty()) {
       LOG(ERROR) << "Unexpected empty partition name.";
       return false;
     }
     if (partition.ranges().empty()) {
       LOG(ERROR) << "Unexpected block ranges for partition " << partition.name();
       return false;
     }
     if (!read_blocks(partition.name(), partition.ranges())) {
       return false;
     }
   }

   return true;
 }

 static int reboot_device() {
   if (android_reboot(ANDROID_RB_RESTART2, 0, nullptr) == -1) {
     LOG(ERROR) << "Failed to reboot.";
     return -1;
   }
   while (true) pause();
 }

 int update_verifier(int argc, char** argv) {
   for (int i = 1; i < argc; i++) {
     LOG(INFO) << "Started with arg " << i << ": " << argv[i];
   }

   sp<IBootControl> module = IBootControl::getService();
   if (module == nullptr) {
     LOG(ERROR) << "Error getting bootctrl module.";
     return reboot_device();
   }

   uint32_t current_slot = module->getCurrentSlot();
   BoolResult is_successful = module->isSlotMarkedSuccessful(current_slot);
   LOG(INFO) << "Booting slot " << current_slot << ": isSlotMarkedSuccessful="
             << static_cast<int32_t>(is_successful);

   if (is_successful == BoolResult::FALSE) {
     // The current slot has not booted successfully.

     bool skip_verification = false;
     std::string verity_mode = android::base::GetProperty("ro.boot.veritymode", "");
     if (verity_mode.empty()) {
       // Skip the verification if ro.boot.veritymode property is not set. This could be a result
       // that device doesn't support dm-verity, or has disabled that.
       LOG(WARNING) << "dm-verity not enabled; marking without verification.";
       skip_verification = true;
     } else if (android::base::EqualsIgnoreCase(verity_mode, "eio")) {
       // We shouldn't see verity in EIO mode if the current slot hasn't booted successfully before.
       // Continue the verification until we fail to read some blocks.
       LOG(WARNING) << "Found dm-verity in EIO mode.";
     } else if (android::base::EqualsIgnoreCase(verity_mode, "disabled")) {
       LOG(WARNING) << "dm-verity in disabled mode; marking without verification.";
       skip_verification = true;
     } else if (verity_mode != "enforcing") {
       LOG(ERROR) << "Unexpected dm-verity mode: " << verity_mode << ", expecting enforcing.";
       return reboot_device();
     }

     if (!skip_verification) {
       static constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
       if (!verify_image(CARE_MAP_FILE)) {
         LOG(ERROR) << "Failed to verify all blocks in care map file.";
         return reboot_device();
       }
     }

     CommandResult cr;
     module->markBootSuccessful([&cr](CommandResult result) { cr = result; });
     if (!cr.success) {
       LOG(ERROR) << "Error marking booted successfully: " << cr.errMsg;
       return reboot_device();
     }
     LOG(INFO) << "Marked slot " << current_slot << " as booted successfully.";
   }

   LOG(INFO) << "Leaving update_verifier.";
   return 0;
 }
	/*
	* 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.
	*/

	/*
	* update_verifier 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
	* (https://source.android.com/devices/tech/ota/ab/#after_reboot).
	*
	* update_verifier relies on device-mapper-verity (dm-verity) to capture any corruption on the
	* partitions being verified (https://source.android.com/security/verifiedboot). The verification
	* will be skipped, if dm-verity is not enabled on the device.
	*
	* Upon detecting verification failures, the device will be rebooted, although the trigger of the
	* reboot depends on the dm-verity mode.
	* enforcing mode: dm-verity reboots the device
	* eio mode: dm-verity fails the read and update_verifier reboots the device
	* other mode: not supported and update_verifier reboots the device
	*
	* All these reboots prevent the device from booting into a known corrupt state. If the device
	* continuously fails to boot into the new slot, the bootloader should mark the slot as unbootable
	* and trigger a fallback to the old slot.
	*
	* The current slot will be marked as having booted successfully if the verifier reaches the end
	* after the verification.
	*/

	#include "update_verifier/update_verifier.h"

	#include <dirent.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>

	#include <algorithm>
	#include <future>
	#include <string>
	#include <vector>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/parseint.h>
	#include <android-base/properties.h>
	#include <android-base/strings.h>
	#include <android-base/unique_fd.h>
	#include <android/hardware/boot/1.0/IBootControl.h>
	#include <cutils/android_reboot.h>

	#include "care_map.pb.h"
	#include "otautil/rangeset.h"

	using android::sp;
	using android::hardware::boot::V1_0::IBootControl;
	using android::hardware::boot::V1_0::BoolResult;
	using android::hardware::boot::V1_0::CommandResult;

	// Find directories in format of "/sys/block/dm-X".
	static int dm_name_filter(const dirent* de) {
	if (android::base::StartsWith(de->d_name, "dm-")) {
	return 1;
	}
	return 0;
	}

	static bool read_blocks(const std::string& partition, const std::string& range_str) {
	if (partition != "system" && partition != "vendor" && partition != "product") {
	LOG(ERROR) << "Invalid partition name \"" << partition << "\"";
	return false;
	}
	// Iterate the content of "/sys/block/dm-X/dm/name". If it matches one of "system", "vendor" or
	// "product", then dm-X is a dm-wrapped device for that target. We will later read all the
	// ("cared") blocks from "/dev/block/dm-X" to ensure the target partition's integrity.
	static constexpr auto DM_PATH_PREFIX = "/sys/block/";
	dirent** namelist;
	int n = scandir(DM_PATH_PREFIX, &namelist, dm_name_filter, alphasort);
	if (n == -1) {
	PLOG(ERROR) << "Failed to scan dir " << DM_PATH_PREFIX;
	return false;
	}
	if (n == 0) {
	LOG(ERROR) << "dm block device not found for " << partition;
	return false;
	}

	static constexpr auto DM_PATH_SUFFIX = "/dm/name";
	static constexpr auto DEV_PATH = "/dev/block/";
	std::string dm_block_device;
	while (n--) {
	std::string path = DM_PATH_PREFIX + std::string(namelist[n]->d_name) + DM_PATH_SUFFIX;
	std::string content;
	if (!android::base::ReadFileToString(path, &content)) {
	PLOG(WARNING) << "Failed to read " << path;
	} else {
	std::string dm_block_name = android::base::Trim(content);
	// AVB is using 'vroot' for the root block device but we're expecting 'system'.
	if (dm_block_name == "vroot") {
	dm_block_name = "system";
	}
	if (dm_block_name == partition) {
	dm_block_device = DEV_PATH + std::string(namelist[n]->d_name);
	while (n--) {
	free(namelist[n]);
	}
	break;
	}
	}
	free(namelist[n]);
	}
	free(namelist);

	if (dm_block_device.empty()) {
	LOG(ERROR) << "Failed to find dm block device for " << partition;
	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).
	RangeSet ranges = RangeSet::Parse(range_str);
	if (!ranges) {
	LOG(ERROR) << "Error parsing RangeSet string " << range_str;
	return false;
	}

	// RangeSet::Split() splits the ranges into multiple groups with same number of blocks (except for
	// the last group).
	size_t thread_num = std::thread::hardware_concurrency() ?: 4;
	std::vector<RangeSet> groups = ranges.Split(thread_num);

	std::vector<std::future<bool>> threads;
	for (const auto& group : groups) {
	auto thread_func = [&group, &dm_block_device, &partition]() {
	android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(dm_block_device.c_str(), O_RDONLY)));
	if (fd.get() == -1) {
	PLOG(ERROR) << "Error reading " << dm_block_device << " for partition " << partition;
	return false;
	}

	static constexpr size_t kBlockSize = 4096;
	std::vector<uint8_t> buf(1024 * kBlockSize);

	size_t block_count = 0;
	for (const auto& range : group) {
	size_t range_start = range.first;
	size_t range_end = range.second;
	if (lseek64(fd.get(), static_cast<off64_t>(range_start) * kBlockSize, SEEK_SET) == -1) {
	PLOG(ERROR) << "lseek to " << range_start << " failed";
	return false;
	}

	size_t remain = (range_end - range_start) * kBlockSize;
	while (remain > 0) {
	size_t to_read = std::min(remain, 1024 * kBlockSize);
	if (!android::base::ReadFully(fd.get(), buf.data(), to_read)) {
	PLOG(ERROR) << "Failed to read blocks " << range_start << " to " << range_end;
	return false;
	}
	remain -= to_read;
	}
	block_count += (range_end - range_start);
	}
	LOG(INFO) << "Finished reading " << block_count << " blocks on " << dm_block_device;
	return true;
	};

	threads.emplace_back(std::async(std::launch::async, thread_func));
	}

	bool ret = true;
	for (auto& t : threads) {
	ret = t.get() && ret;
	}
	LOG(INFO) << "Finished reading blocks on " << dm_block_device << " with " << thread_num
	<< " threads.";
	return ret;
	}

	static bool process_care_map_plain_text(const std::string& care_map_contents) {
	// care_map file has up to six lines, where every two lines make a pair. Within each pair, the
	// first line has the partition name (e.g. "system"), while the second line holds the ranges of
	// all the blocks to verify.
	std::vector<std::string> lines =
	android::base::Split(android::base::Trim(care_map_contents), "\n");
	if (lines.size() != 2 && lines.size() != 4 && lines.size() != 6) {
	LOG(ERROR) << "Invalid lines in care_map: found " << lines.size()
	<< " lines, expecting 2 or 4 or 6 lines.";
	return false;
	}

	for (size_t i = 0; i < lines.size(); i += 2) {
	// We're seeing an N care_map.txt. Skip the verification since it's not compatible with O
	// update_verifier (the last few metadata blocks can't be read via device mapper).
	if (android::base::StartsWith(lines[i], "/dev/block/")) {
	LOG(WARNING) << "Found legacy care_map.txt; skipped.";
	return true;
	}
	if (!read_blocks(lines[i], lines[i+1])) {
	return false;
	}
	}

	return true;
	}

	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) {
	PLOG(WARNING) << "Failed to open " << care_map_name;
	return true;
	}

	std::string file_content;
	if (!android::base::ReadFdToString(care_map_fd.get(), &file_content)) {
	PLOG(ERROR) << "Failed to read " << care_map_name;
	return false;
	}

	if (file_content.empty()) {
	LOG(ERROR) << "Unexpected empty care map";
	return false;
	}

	UpdateVerifier::CareMap care_map;
	// Falls back to use the plain text version if we cannot parse the file as protobuf message.
	if (!care_map.ParseFromString(file_content)) {
	return process_care_map_plain_text(file_content);
	}

	for (const auto& partition : care_map.partitions()) {
	if (partition.name().empty()) {
	LOG(ERROR) << "Unexpected empty partition name.";
	return false;
	}
	if (partition.ranges().empty()) {
	LOG(ERROR) << "Unexpected block ranges for partition " << partition.name();
	return false;
	}
	if (!read_blocks(partition.name(), partition.ranges())) {
	return false;
	}
	}

	return true;
	}

	static int reboot_device() {
	if (android_reboot(ANDROID_RB_RESTART2, 0, nullptr) == -1) {
	LOG(ERROR) << "Failed to reboot.";
	return -1;
	}
	while (true) pause();
	}

	int update_verifier(int argc, char** argv) {
	for (int i = 1; i < argc; i++) {
	LOG(INFO) << "Started with arg " << i << ": " << argv[i];
	}

	sp<IBootControl> module = IBootControl::getService();
	if (module == nullptr) {
	LOG(ERROR) << "Error getting bootctrl module.";
	return reboot_device();
	}

	uint32_t current_slot = module->getCurrentSlot();
	BoolResult is_successful = module->isSlotMarkedSuccessful(current_slot);
	LOG(INFO) << "Booting slot " << current_slot << ": isSlotMarkedSuccessful="
	<< static_cast<int32_t>(is_successful);

	if (is_successful == BoolResult::FALSE) {
	// The current slot has not booted successfully.

	bool skip_verification = false;
	std::string verity_mode = android::base::GetProperty("ro.boot.veritymode", "");
	if (verity_mode.empty()) {
	// Skip the verification if ro.boot.veritymode property is not set. This could be a result
	// that device doesn't support dm-verity, or has disabled that.
	LOG(WARNING) << "dm-verity not enabled; marking without verification.";
	skip_verification = true;
	} else if (android::base::EqualsIgnoreCase(verity_mode, "eio")) {
	// We shouldn't see verity in EIO mode if the current slot hasn't booted successfully before.
	// Continue the verification until we fail to read some blocks.
	LOG(WARNING) << "Found dm-verity in EIO mode.";
	} else if (android::base::EqualsIgnoreCase(verity_mode, "disabled")) {
	LOG(WARNING) << "dm-verity in disabled mode; marking without verification.";
	skip_verification = true;
	} else if (verity_mode != "enforcing") {
	LOG(ERROR) << "Unexpected dm-verity mode: " << verity_mode << ", expecting enforcing.";
	return reboot_device();
	}

	if (!skip_verification) {
	static constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
	if (!verify_image(CARE_MAP_FILE)) {
	LOG(ERROR) << "Failed to verify all blocks in care map file.";
	return reboot_device();
	}
	}

	CommandResult cr;
	module->markBootSuccessful([&cr](CommandResult result) { cr = result; });
	if (!cr.success) {
	LOG(ERROR) << "Error marking booted successfully: " << cr.errMsg;
	return reboot_device();
	}
	LOG(INFO) << "Marked slot " << current_slot << " as booted successfully.";
	}

	LOG(INFO) << "Leaving update_verifier.";
	return 0;
	}