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//
// Copyright (C) 2012 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.
//
#include "update_engine/payload_consumer/filesystem_verifier_action.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <algorithm>
#include <cstdlib>
#include <memory>
#include <string>
#include <utility>
#include <base/bind.h>
#include <base/strings/string_util.h>
#include <brillo/data_encoding.h>
#include <brillo/message_loops/message_loop.h>
#include <brillo/secure_blob.h>
#include <brillo/streams/file_stream.h>
#include "common/error_code.h"
#include "payload_generator/delta_diff_generator.h"
#include "update_engine/common/utils.h"
#include "update_engine/payload_consumer/file_descriptor.h"
using brillo::data_encoding::Base64Encode;
using std::string;
// On a partition with verity enabled, we expect to see the following format:
// ===================================================
// Normal Filesystem Data
// (this should take most of the space, like over 90%)
// ===================================================
// Hash tree
// ~0.8% (e.g. 16M for 2GB image)
// ===================================================
// FEC data
// ~0.8%
// ===================================================
// Footer
// 4K
// ===================================================
// For OTA that doesn't do on device verity computation, hash tree and fec data
// are written during DownloadAction as a regular InstallOp, so no special
// handling needed, we can just read the entire partition in 1 go.
// Verity enabled case: Only Normal FS data is written during download action.
// When hasing the entire partition, we will need to build the hash tree, write
// it to disk, then build FEC, and write it to disk. Therefore, it is important
// that we finish writing hash tree before we attempt to read & hash it. The
// same principal applies to FEC data.
// |verity_writer_| handles building and
// writing of FEC/HashTree, we just need to be careful when reading.
// Specifically, we must stop at beginning of Hash tree, let |verity_writer_|
// write both hash tree and FEC, then continue reading the remaining part of
// partition.
namespace chromeos_update_engine {
namespace {
const off_t kReadFileBufferSize = 128 * 1024;
constexpr float kVerityProgressPercent = 0.6;
} // namespace
void FilesystemVerifierAction::PerformAction() {
// Will tell the ActionProcessor we've failed if we return.
ScopedActionCompleter abort_action_completer(processor_, this);
if (!HasInputObject()) {
LOG(ERROR) << "FilesystemVerifierAction missing input object.";
return;
}
install_plan_ = GetInputObject();
if (install_plan_.partitions.empty()) {
LOG(INFO) << "No partitions to verify.";
if (HasOutputPipe())
SetOutputObject(install_plan_);
abort_action_completer.set_code(ErrorCode::kSuccess);
return;
}
install_plan_.Dump();
StartPartitionHashing();
abort_action_completer.set_should_complete(false);
}
void FilesystemVerifierAction::TerminateProcessing() {
cancelled_ = true;
Cleanup(ErrorCode::kSuccess); // error code is ignored if canceled_ is true.
}
void FilesystemVerifierAction::Cleanup(ErrorCode code) {
partition_fd_.reset();
// This memory is not used anymore.
buffer_.clear();
// If we didn't write verity, partitions were maped. Releaase resource now.
if (!install_plan_.write_verity &&
dynamic_control_->UpdateUsesSnapshotCompression()) {
LOG(INFO) << "Not writing verity and VABC is enabled, unmapping all "
"partitions";
dynamic_control_->UnmapAllPartitions();
}
if (cancelled_)
return;
if (code == ErrorCode::kSuccess && HasOutputPipe())
SetOutputObject(install_plan_);
UpdateProgress(1.0);
processor_->ActionComplete(this, code);
}
void FilesystemVerifierAction::UpdateProgress(double progress) {
if (delegate_ != nullptr) {
delegate_->OnVerifyProgressUpdate(progress);
}
}
void FilesystemVerifierAction::UpdatePartitionProgress(double progress) {
// We don't consider sizes of each partition. Every partition
// has the same length on progress bar.
// TODO(b/186087589): Take sizes of each partition into account.
UpdateProgress((progress + partition_index_) /
install_plan_.partitions.size());
}
bool FilesystemVerifierAction::InitializeFdVABC(bool should_write_verity) {
const InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
if (!should_write_verity) {
// In VABC, we cannot map/unmap partitions w/o first closing ALL fds first.
// Since this function might be called inside a ScheduledTask, the closure
// might have a copy of partition_fd_ when executing this function. Which
// means even if we do |partition_fd_.reset()| here, there's a chance that
// underlying fd isn't closed until we return. This is unacceptable, we need
// to close |partition_fd| right away.
if (partition_fd_) {
partition_fd_->Close();
partition_fd_.reset();
}
// In VABC, if we are not writing verity, just map all partitions,
// and read using regular fd on |postinstall_mount_device| .
// All read will go through snapuserd, which provides a consistent
// view: device will use snapuserd to read partition during boot.
// b/186196758
// Call UnmapAllPartitions() first, because if we wrote verity before, these
// writes won't be visible to previously opened snapuserd daemon. To ensure
// that we will see the most up to date data from partitions, call Unmap()
// then Map() to re-spin daemon.
dynamic_control_->UnmapAllPartitions();
dynamic_control_->MapAllPartitions();
return InitializeFd(partition.readonly_target_path);
}
partition_fd_ =
dynamic_control_->OpenCowFd(partition.name, partition.source_path, true);
if (!partition_fd_) {
LOG(ERROR) << "OpenCowReader(" << partition.name << ", "
<< partition.source_path << ") failed.";
return false;
}
partition_size_ = partition.target_size;
return true;
}
bool FilesystemVerifierAction::InitializeFd(const std::string& part_path) {
partition_fd_ = FileDescriptorPtr(new EintrSafeFileDescriptor());
const bool write_verity = ShouldWriteVerity();
int flags = write_verity ? O_RDWR : O_RDONLY;
if (!utils::SetBlockDeviceReadOnly(part_path, !write_verity)) {
LOG(WARNING) << "Failed to set block device " << part_path << " as "
<< (write_verity ? "writable" : "readonly");
}
if (!partition_fd_->Open(part_path.c_str(), flags)) {
LOG(ERROR) << "Unable to open " << part_path << " for reading.";
return false;
}
return true;
}
void FilesystemVerifierAction::WriteVerityAndHashPartition(
FileDescriptorPtr fd,
const off64_t start_offset,
const off64_t end_offset,
void* buffer,
const size_t buffer_size) {
if (start_offset >= end_offset) {
LOG_IF(WARNING, start_offset > end_offset)
<< "start_offset is greater than end_offset : " << start_offset << " > "
<< end_offset;
if (!verity_writer_->Finalize(fd, fd)) {
LOG(ERROR) << "Failed to write verity data";
Cleanup(ErrorCode::kVerityCalculationError);
return;
}
if (dynamic_control_->UpdateUsesSnapshotCompression()) {
// Spin up snapuserd to read fs.
if (!InitializeFdVABC(false)) {
LOG(ERROR) << "Failed to map all partitions";
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
}
HashPartition(partition_fd_, 0, partition_size_, buffer, buffer_size);
return;
}
const auto cur_offset = fd->Seek(start_offset, SEEK_SET);
if (cur_offset != start_offset) {
PLOG(ERROR) << "Failed to seek to offset: " << start_offset;
Cleanup(ErrorCode::kVerityCalculationError);
return;
}
const auto read_size =
std::min<size_t>(buffer_size, end_offset - start_offset);
const auto bytes_read = fd->Read(buffer, read_size);
if (bytes_read < 0 || static_cast<size_t>(bytes_read) != read_size) {
PLOG(ERROR) << "Failed to read offset " << start_offset << " expected "
<< read_size << " bytes, actual: " << bytes_read;
Cleanup(ErrorCode::kVerityCalculationError);
return;
}
if (!verity_writer_->Update(
start_offset, static_cast<const uint8_t*>(buffer), read_size)) {
LOG(ERROR) << "VerityWriter::Update() failed";
Cleanup(ErrorCode::kVerityCalculationError);
return;
}
UpdatePartitionProgress((start_offset + bytes_read) * 1.0f / partition_size_ *
kVerityProgressPercent);
CHECK(pending_task_id_.PostTask(
FROM_HERE,
base::BindOnce(&FilesystemVerifierAction::WriteVerityAndHashPartition,
base::Unretained(this),
fd,
start_offset + bytes_read,
end_offset,
buffer,
buffer_size)));
}
void FilesystemVerifierAction::HashPartition(FileDescriptorPtr fd,
const off64_t start_offset,
const off64_t end_offset,
void* buffer,
const size_t buffer_size) {
if (start_offset >= end_offset) {
LOG_IF(WARNING, start_offset > end_offset)
<< "start_offset is greater than end_offset : " << start_offset << " > "
<< end_offset;
FinishPartitionHashing();
return;
}
const auto cur_offset = fd->Seek(start_offset, SEEK_SET);
if (cur_offset != start_offset) {
PLOG(ERROR) << "Failed to seek to offset: " << start_offset;
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
const auto read_size =
std::min<size_t>(buffer_size, end_offset - start_offset);
const auto bytes_read = fd->Read(buffer, read_size);
if (bytes_read < 0 || static_cast<size_t>(bytes_read) != read_size) {
PLOG(ERROR) << "Failed to read offset " << start_offset << " expected "
<< read_size << " bytes, actual: " << bytes_read;
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
if (!hasher_->Update(buffer, read_size)) {
LOG(ERROR) << "Hasher updated failed on offset" << start_offset;
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
const auto progress = (start_offset + bytes_read) * 1.0f / partition_size_;
UpdatePartitionProgress(progress * (1 - kVerityProgressPercent) +
kVerityProgressPercent);
CHECK(pending_task_id_.PostTask(
FROM_HERE,
base::BindOnce(&FilesystemVerifierAction::HashPartition,
base::Unretained(this),
fd,
start_offset + bytes_read,
end_offset,
buffer,
buffer_size)));
}
void FilesystemVerifierAction::StartPartitionHashing() {
if (partition_index_ == install_plan_.partitions.size()) {
if (!install_plan_.untouched_dynamic_partitions.empty()) {
LOG(INFO) << "Verifying extents of untouched dynamic partitions ["
<< base::JoinString(install_plan_.untouched_dynamic_partitions,
", ")
<< "]";
if (!dynamic_control_->VerifyExtentsForUntouchedPartitions(
install_plan_.source_slot,
install_plan_.target_slot,
install_plan_.untouched_dynamic_partitions)) {
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
}
Cleanup(ErrorCode::kSuccess);
return;
}
const InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
const auto& part_path = GetPartitionPath();
partition_size_ = GetPartitionSize();
LOG(INFO) << "Hashing partition " << partition_index_ << " ("
<< partition.name << ") on device " << part_path;
auto success = false;
if (IsVABC(partition)) {
success = InitializeFdVABC(ShouldWriteVerity());
} else {
if (part_path.empty()) {
if (partition_size_ == 0) {
LOG(INFO) << "Skip hashing partition " << partition_index_ << " ("
<< partition.name << ") because size is 0.";
partition_index_++;
StartPartitionHashing();
return;
}
LOG(ERROR) << "Cannot hash partition " << partition_index_ << " ("
<< partition.name
<< ") because its device path cannot be determined.";
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
success = InitializeFd(part_path);
}
if (!success) {
Cleanup(ErrorCode::kFilesystemVerifierError);
return;
}
buffer_.resize(kReadFileBufferSize);
hasher_ = std::make_unique<HashCalculator>();
offset_ = 0;
filesystem_data_end_ = partition_size_;
if (partition.fec_offset > 0) {
CHECK_LE(partition.hash_tree_offset, partition.fec_offset)
<< " Hash tree is expected to come before FEC data";
}
if (partition.hash_tree_offset != 0) {
filesystem_data_end_ = partition.hash_tree_offset;
} else if (partition.fec_offset != 0) {
filesystem_data_end_ = partition.fec_offset;
}
if (ShouldWriteVerity()) {
LOG(INFO) << "Verity writes enabled on partition " << partition.name;
if (!verity_writer_->Init(partition)) {
LOG(INFO) << "Verity writes enabled on partition " << partition.name;
Cleanup(ErrorCode::kVerityCalculationError);
return;
}
WriteVerityAndHashPartition(
partition_fd_, 0, filesystem_data_end_, buffer_.data(), buffer_.size());
} else {
LOG(INFO) << "Verity writes disabled on partition " << partition.name;
HashPartition(
partition_fd_, 0, partition_size_, buffer_.data(), buffer_.size());
}
}
bool FilesystemVerifierAction::IsVABC(
const InstallPlan::Partition& partition) const {
return dynamic_control_->UpdateUsesSnapshotCompression() &&
verifier_step_ == VerifierStep::kVerifyTargetHash &&
dynamic_control_->IsDynamicPartition(partition.name,
install_plan_.target_slot);
}
const std::string& FilesystemVerifierAction::GetPartitionPath() const {
const InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
switch (verifier_step_) {
case VerifierStep::kVerifySourceHash:
return partition.source_path;
case VerifierStep::kVerifyTargetHash:
if (IsVABC(partition)) {
return partition.readonly_target_path;
} else {
return partition.target_path;
}
}
}
size_t FilesystemVerifierAction::GetPartitionSize() const {
const InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
switch (verifier_step_) {
case VerifierStep::kVerifySourceHash:
return partition.source_size;
case VerifierStep::kVerifyTargetHash:
return partition.target_size;
}
}
bool FilesystemVerifierAction::ShouldWriteVerity() {
const InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
return verifier_step_ == VerifierStep::kVerifyTargetHash &&
install_plan_.write_verity &&
(partition.hash_tree_size > 0 || partition.fec_size > 0);
}
void FilesystemVerifierAction::FinishPartitionHashing() {
if (!hasher_->Finalize()) {
LOG(ERROR) << "Unable to finalize the hash.";
Cleanup(ErrorCode::kError);
return;
}
InstallPlan::Partition& partition =
install_plan_.partitions[partition_index_];
LOG(INFO) << "Hash of " << partition.name << ": "
<< Base64Encode(hasher_->raw_hash());
switch (verifier_step_) {
case VerifierStep::kVerifyTargetHash:
if (partition.target_hash != hasher_->raw_hash()) {
LOG(ERROR) << "New '" << partition.name
<< "' partition verification failed.";
if (partition.source_hash.empty()) {
// No need to verify source if it is a full payload.
Cleanup(ErrorCode::kNewRootfsVerificationError);
return;
}
// If we have not verified source partition yet, now that the target
// partition does not match, and it's not a full payload, we need to
// switch to kVerifySourceHash step to check if it's because the
// source partition does not match either.
verifier_step_ = VerifierStep::kVerifySourceHash;
} else {
partition_index_++;
}
break;
case VerifierStep::kVerifySourceHash:
if (partition.source_hash != hasher_->raw_hash()) {
LOG(ERROR) << "Old '" << partition.name
<< "' partition verification failed.";
LOG(ERROR) << "This is a server-side error due to mismatched delta"
<< " update image!";
LOG(ERROR) << "The delta I've been given contains a " << partition.name
<< " delta update that must be applied over a "
<< partition.name << " with a specific checksum, but the "
<< partition.name
<< " we're starting with doesn't have that checksum! This"
" means that the delta I've been given doesn't match my"
" existing system. The "
<< partition.name << " partition I have has hash: "
<< Base64Encode(hasher_->raw_hash())
<< " but the update expected me to have "
<< Base64Encode(partition.source_hash) << " .";
LOG(INFO) << "To get the checksum of the " << partition.name
<< " partition run this command: dd if="
<< partition.source_path
<< " bs=1M count=" << partition.source_size
<< " iflag=count_bytes 2>/dev/null | openssl dgst -sha256 "
"-binary | openssl base64";
LOG(INFO) << "To get the checksum of partitions in a bin file, "
<< "run: .../src/scripts/sha256_partitions.sh .../file.bin";
Cleanup(ErrorCode::kDownloadStateInitializationError);
return;
}
// The action will skip kVerifySourceHash step if target partition hash
// matches, if we are in this step, it means target hash does not match,
// and now that the source partition hash matches, we should set the
// error code to reflect the error in target partition. We only need to
// verify the source partition which the target hash does not match, the
// rest of the partitions don't matter.
Cleanup(ErrorCode::kNewRootfsVerificationError);
return;
}
// Start hashing the next partition, if any.
hasher_.reset();
buffer_.clear();
if (partition_fd_) {
partition_fd_->Close();
partition_fd_.reset();
}
StartPartitionHashing();
}
} // namespace chromeos_update_engine