payload_consumer/verity_writer_android.cc - android_system_update_engine - Gitiles

 //
 // Copyright (C) 2018 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/verity_writer_android.h"

 #include <fcntl.h>

 #include <algorithm>
 #include <memory>

 #include <base/logging.h>
 #include <base/posix/eintr_wrapper.h>
 #include <fec/ecc.h>
 extern "C" {
 #include <fec.h>
 }

 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/cached_file_descriptor.h"
 #include "update_engine/payload_consumer/file_descriptor.h"

 namespace chromeos_update_engine {

 namespace verity_writer {
 std::unique_ptr<VerityWriterInterface> CreateVerityWriter() {
   return std::make_unique<VerityWriterAndroid>();
 }
 }  // namespace verity_writer

 bool VerityWriterAndroid::Init(const InstallPlan::Partition& partition) {
   partition_ = &partition;

   if (partition_->hash_tree_size != 0) {
     auto hash_function =
         HashTreeBuilder::HashFunction(partition_->hash_tree_algorithm);
     if (hash_function == nullptr) {
       LOG(ERROR) << "Verity hash algorithm not supported: "
                  << partition_->hash_tree_algorithm;
       return false;
     }
     hash_tree_builder_ = std::make_unique<HashTreeBuilder>(
         partition_->block_size, hash_function);
     TEST_AND_RETURN_FALSE(hash_tree_builder_->Initialize(
         partition_->hash_tree_data_size, partition_->hash_tree_salt));
     if (hash_tree_builder_->CalculateSize(partition_->hash_tree_data_size) !=
         partition_->hash_tree_size) {
       LOG(ERROR) << "Verity hash tree size does not match, stored: "
                  << partition_->hash_tree_size << ", calculated: "
                  << hash_tree_builder_->CalculateSize(
                         partition_->hash_tree_data_size);
       return false;
     }
   }
   total_offset_ = 0;
   return true;
 }

 bool VerityWriterAndroid::Update(const uint64_t offset,
                                  const uint8_t* buffer,
                                  size_t size) {
   if (offset != total_offset_) {
     LOG(ERROR) << "Sequential read expected, expected to read at: "
                << total_offset_ << " actual read occurs at: " << offset;
     return false;
   }
   if (partition_->hash_tree_size != 0) {
     const uint64_t hash_tree_data_end =
         partition_->hash_tree_data_offset + partition_->hash_tree_data_size;
     const uint64_t start_offset =
         std::max(offset, partition_->hash_tree_data_offset);
     if (offset + size > hash_tree_data_end) {
       LOG(WARNING)
           << "Reading past hash_tree_data_end, something is probably "
              "wrong, might cause incorrect hash of partitions. offset: "
           << offset << " size: " << size
           << " hash_tree_data_end: " << hash_tree_data_end;
     }
     const uint64_t end_offset = std::min(offset + size, hash_tree_data_end);
     if (start_offset < end_offset) {
       TEST_AND_RETURN_FALSE(hash_tree_builder_->Update(
           buffer + start_offset - offset, end_offset - start_offset));

       if (end_offset == hash_tree_data_end) {
         LOG(INFO)
             << "Read everything before hash tree. Ready to write hash tree.";
       }
     }
   }
   total_offset_ += size;

   return true;
 }

 bool VerityWriterAndroid::Finalize(FileDescriptor* read_fd,
                                    FileDescriptor* write_fd) {
   const auto hash_tree_data_end =
       partition_->hash_tree_data_offset + partition_->hash_tree_data_size;
   if (total_offset_ < hash_tree_data_end) {
     LOG(ERROR) << "Read up to " << total_offset_
                << " when we are expecting to read everything "
                   "before "
                << hash_tree_data_end;
     return false;
   }
   // All hash tree data blocks has been hashed, write hash tree to disk.
   LOG(INFO) << "Writing verity hash tree to "
             << partition_->readonly_target_path;
   if (hash_tree_builder_) {
     TEST_AND_RETURN_FALSE(hash_tree_builder_->BuildHashTree());
     TEST_AND_RETURN_FALSE_ERRNO(
         write_fd->Seek(partition_->hash_tree_offset, SEEK_SET));
     auto success =
         hash_tree_builder_->WriteHashTree([write_fd](auto data, auto size) {
           return utils::WriteAll(write_fd, data, size);
         });
     // hashtree builder already prints error messages.
     TEST_AND_RETURN_FALSE(success);
     hash_tree_builder_.reset();
   }
   if (partition_->fec_size != 0) {
     LOG(INFO) << "Writing verity FEC to " << partition_->readonly_target_path;
     TEST_AND_RETURN_FALSE(EncodeFEC(read_fd,
                                     write_fd,
                                     partition_->fec_data_offset,
                                     partition_->fec_data_size,
                                     partition_->fec_offset,
                                     partition_->fec_size,
                                     partition_->fec_roots,
                                     partition_->block_size,
                                     false /* verify_mode */));
   }
   return true;
 }

 bool VerityWriterAndroid::EncodeFEC(FileDescriptor* read_fd,
                                     FileDescriptor* write_fd,
                                     uint64_t data_offset,
                                     uint64_t data_size,
                                     uint64_t fec_offset,
                                     uint64_t fec_size,
                                     uint32_t fec_roots,
                                     uint32_t block_size,
                                     bool verify_mode) {
   TEST_AND_RETURN_FALSE(data_size % block_size == 0);
   TEST_AND_RETURN_FALSE(fec_roots >= 0 && fec_roots < FEC_RSM);
   // This is the N in RS(M, N), which is the number of bytes for each rs block.
   size_t rs_n = FEC_RSM - fec_roots;
   uint64_t rounds = utils::DivRoundUp(data_size / block_size, rs_n);
   TEST_AND_RETURN_FALSE(rounds * fec_roots * block_size == fec_size);

   std::unique_ptr<void, decltype(&free_rs_char)> rs_char(
       init_rs_char(FEC_PARAMS(fec_roots)), &free_rs_char);
   TEST_AND_RETURN_FALSE(rs_char != nullptr);
   // Cache at most 1MB of fec data, in VABC, we need to re-open fd if we
   // perform a read() operation after write(). So reduce the number of writes
   // can save unnecessary re-opens.
   UnownedCachedFileDescriptor cache_fd(write_fd, 1 * (1 << 20));
   write_fd = &cache_fd;

   for (size_t i = 0; i < rounds; i++) {
     // Encodes |block_size| number of rs blocks each round so that we can read
     // one block each time instead of 1 byte to increase random read
     // performance. This uses about 1 MiB memory for 4K block size.
     brillo::Blob rs_blocks(block_size * rs_n);
     for (size_t j = 0; j < rs_n; j++) {
       brillo::Blob buffer(block_size, 0);
       uint64_t offset =
           fec_ecc_interleave(i * rs_n * block_size + j, rs_n, rounds);
       // Don't read past |data_size|, treat them as 0.
       if (offset < data_size) {
         ssize_t bytes_read = 0;
         TEST_AND_RETURN_FALSE(utils::PReadAll(read_fd,
                                               buffer.data(),
                                               buffer.size(),
                                               data_offset + offset,
                                               &bytes_read));
         TEST_AND_RETURN_FALSE(bytes_read >= 0);
         TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) == buffer.size());
       }
       for (size_t k = 0; k < buffer.size(); k++) {
         rs_blocks[k * rs_n + j] = buffer[k];
       }
     }
     brillo::Blob fec(block_size * fec_roots);
     for (size_t j = 0; j < block_size; j++) {
       // Encode [j * rs_n : (j + 1) * rs_n) in |rs_blocks| and write |fec_roots|
       // number of parity bytes to |j * fec_roots| in |fec|.
       encode_rs_char(rs_char.get(),
                      rs_blocks.data() + j * rs_n,
                      fec.data() + j * fec_roots);
     }

     if (verify_mode) {
       brillo::Blob fec_read(fec.size());
       ssize_t bytes_read = 0;
       TEST_AND_RETURN_FALSE(utils::PReadAll(
           read_fd, fec_read.data(), fec_read.size(), fec_offset, &bytes_read));
       TEST_AND_RETURN_FALSE(bytes_read >= 0);
       TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) == fec_read.size());
       TEST_AND_RETURN_FALSE(fec == fec_read);
     } else {
       CHECK(write_fd);
       write_fd->Seek(fec_offset, SEEK_SET);
       if (!utils::WriteAll(write_fd, fec.data(), fec.size())) {
         PLOG(ERROR) << "EncodeFEC write() failed";
         return false;
       }
     }
     fec_offset += fec.size();
   }
   write_fd->Flush();
   return true;
 }

 bool VerityWriterAndroid::EncodeFEC(const std::string& path,
                                     uint64_t data_offset,
                                     uint64_t data_size,
                                     uint64_t fec_offset,
                                     uint64_t fec_size,
                                     uint32_t fec_roots,
                                     uint32_t block_size,
                                     bool verify_mode) {
   EintrSafeFileDescriptor fd;
   TEST_AND_RETURN_FALSE(fd.Open(path.c_str(), verify_mode ? O_RDONLY : O_RDWR));
   return EncodeFEC(&fd,
                    &fd,
                    data_offset,
                    data_size,
                    fec_offset,
                    fec_size,
                    fec_roots,
                    block_size,
                    verify_mode);
 }
 }  // namespace chromeos_update_engine
	//
	// Copyright (C) 2018 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/verity_writer_android.h"

	#include <fcntl.h>

	#include <algorithm>
	#include <memory>

	#include <base/logging.h>
	#include <base/posix/eintr_wrapper.h>
	#include <fec/ecc.h>
	extern "C" {
	#include <fec.h>
	}

	#include "update_engine/common/utils.h"
	#include "update_engine/payload_consumer/cached_file_descriptor.h"
	#include "update_engine/payload_consumer/file_descriptor.h"

	namespace chromeos_update_engine {

	namespace verity_writer {
	std::unique_ptr<VerityWriterInterface> CreateVerityWriter() {
	return std::make_unique<VerityWriterAndroid>();
	}
	} // namespace verity_writer

	bool VerityWriterAndroid::Init(const InstallPlan::Partition& partition) {
	partition_ = &partition;

	if (partition_->hash_tree_size != 0) {
	auto hash_function =
	HashTreeBuilder::HashFunction(partition_->hash_tree_algorithm);
	if (hash_function == nullptr) {
	LOG(ERROR) << "Verity hash algorithm not supported: "
	<< partition_->hash_tree_algorithm;
	return false;
	}
	hash_tree_builder_ = std::make_unique<HashTreeBuilder>(
	partition_->block_size, hash_function);
	TEST_AND_RETURN_FALSE(hash_tree_builder_->Initialize(
	partition_->hash_tree_data_size, partition_->hash_tree_salt));
	if (hash_tree_builder_->CalculateSize(partition_->hash_tree_data_size) !=
	partition_->hash_tree_size) {
	LOG(ERROR) << "Verity hash tree size does not match, stored: "
	<< partition_->hash_tree_size << ", calculated: "
	<< hash_tree_builder_->CalculateSize(
	partition_->hash_tree_data_size);
	return false;
	}
	}
	total_offset_ = 0;
	return true;
	}

	bool VerityWriterAndroid::Update(const uint64_t offset,
	const uint8_t* buffer,
	size_t size) {
	if (offset != total_offset_) {
	LOG(ERROR) << "Sequential read expected, expected to read at: "
	<< total_offset_ << " actual read occurs at: " << offset;
	return false;
	}
	if (partition_->hash_tree_size != 0) {
	const uint64_t hash_tree_data_end =
	partition_->hash_tree_data_offset + partition_->hash_tree_data_size;
	const uint64_t start_offset =
	std::max(offset, partition_->hash_tree_data_offset);
	if (offset + size > hash_tree_data_end) {
	LOG(WARNING)
	<< "Reading past hash_tree_data_end, something is probably "
	"wrong, might cause incorrect hash of partitions. offset: "
	<< offset << " size: " << size
	<< " hash_tree_data_end: " << hash_tree_data_end;
	}
	const uint64_t end_offset = std::min(offset + size, hash_tree_data_end);
	if (start_offset < end_offset) {
	TEST_AND_RETURN_FALSE(hash_tree_builder_->Update(
	buffer + start_offset - offset, end_offset - start_offset));

	if (end_offset == hash_tree_data_end) {
	LOG(INFO)
	<< "Read everything before hash tree. Ready to write hash tree.";
	}
	}
	}
	total_offset_ += size;

	return true;
	}

	bool VerityWriterAndroid::Finalize(FileDescriptor* read_fd,
	FileDescriptor* write_fd) {
	const auto hash_tree_data_end =
	partition_->hash_tree_data_offset + partition_->hash_tree_data_size;
	if (total_offset_ < hash_tree_data_end) {
	LOG(ERROR) << "Read up to " << total_offset_
	<< " when we are expecting to read everything "
	"before "
	<< hash_tree_data_end;
	return false;
	}
	// All hash tree data blocks has been hashed, write hash tree to disk.
	LOG(INFO) << "Writing verity hash tree to "
	<< partition_->readonly_target_path;
	if (hash_tree_builder_) {
	TEST_AND_RETURN_FALSE(hash_tree_builder_->BuildHashTree());
	TEST_AND_RETURN_FALSE_ERRNO(
	write_fd->Seek(partition_->hash_tree_offset, SEEK_SET));
	auto success =
	hash_tree_builder_->WriteHashTree([write_fd](auto data, auto size) {
	return utils::WriteAll(write_fd, data, size);
	});
	// hashtree builder already prints error messages.
	TEST_AND_RETURN_FALSE(success);
	hash_tree_builder_.reset();
	}
	if (partition_->fec_size != 0) {
	LOG(INFO) << "Writing verity FEC to " << partition_->readonly_target_path;
	TEST_AND_RETURN_FALSE(EncodeFEC(read_fd,
	write_fd,
	partition_->fec_data_offset,
	partition_->fec_data_size,
	partition_->fec_offset,
	partition_->fec_size,
	partition_->fec_roots,
	partition_->block_size,
	false /* verify_mode */));
	}
	return true;
	}

	bool VerityWriterAndroid::EncodeFEC(FileDescriptor* read_fd,
	FileDescriptor* write_fd,
	uint64_t data_offset,
	uint64_t data_size,
	uint64_t fec_offset,
	uint64_t fec_size,
	uint32_t fec_roots,
	uint32_t block_size,
	bool verify_mode) {
	TEST_AND_RETURN_FALSE(data_size % block_size == 0);
	TEST_AND_RETURN_FALSE(fec_roots >= 0 && fec_roots < FEC_RSM);
	// This is the N in RS(M, N), which is the number of bytes for each rs block.
	size_t rs_n = FEC_RSM - fec_roots;
	uint64_t rounds = utils::DivRoundUp(data_size / block_size, rs_n);
	TEST_AND_RETURN_FALSE(rounds * fec_roots * block_size == fec_size);

	std::unique_ptr<void, decltype(&free_rs_char)> rs_char(
	init_rs_char(FEC_PARAMS(fec_roots)), &free_rs_char);
	TEST_AND_RETURN_FALSE(rs_char != nullptr);
	// Cache at most 1MB of fec data, in VABC, we need to re-open fd if we
	// perform a read() operation after write(). So reduce the number of writes
	// can save unnecessary re-opens.
	UnownedCachedFileDescriptor cache_fd(write_fd, 1 * (1 << 20));
	write_fd = &cache_fd;

	for (size_t i = 0; i < rounds; i++) {
	// Encodes \|block_size\| number of rs blocks each round so that we can read
	// one block each time instead of 1 byte to increase random read
	// performance. This uses about 1 MiB memory for 4K block size.
	brillo::Blob rs_blocks(block_size * rs_n);
	for (size_t j = 0; j < rs_n; j++) {
	brillo::Blob buffer(block_size, 0);
	uint64_t offset =
	fec_ecc_interleave(i * rs_n * block_size + j, rs_n, rounds);
	// Don't read past \|data_size\|, treat them as 0.
	if (offset < data_size) {
	ssize_t bytes_read = 0;
	TEST_AND_RETURN_FALSE(utils::PReadAll(read_fd,
	buffer.data(),
	buffer.size(),
	data_offset + offset,
	&bytes_read));
	TEST_AND_RETURN_FALSE(bytes_read >= 0);
	TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) == buffer.size());
	}
	for (size_t k = 0; k < buffer.size(); k++) {
	rs_blocks[k * rs_n + j] = buffer[k];
	}
	}
	brillo::Blob fec(block_size * fec_roots);
	for (size_t j = 0; j < block_size; j++) {
	// Encode [j * rs_n : (j + 1) * rs_n) in \|rs_blocks\| and write \|fec_roots\|
	// number of parity bytes to \|j * fec_roots\| in \|fec\|.
	encode_rs_char(rs_char.get(),
	rs_blocks.data() + j * rs_n,
	fec.data() + j * fec_roots);
	}

	if (verify_mode) {
	brillo::Blob fec_read(fec.size());
	ssize_t bytes_read = 0;
	TEST_AND_RETURN_FALSE(utils::PReadAll(
	read_fd, fec_read.data(), fec_read.size(), fec_offset, &bytes_read));
	TEST_AND_RETURN_FALSE(bytes_read >= 0);
	TEST_AND_RETURN_FALSE(static_cast<size_t>(bytes_read) == fec_read.size());
	TEST_AND_RETURN_FALSE(fec == fec_read);
	} else {
	CHECK(write_fd);
	write_fd->Seek(fec_offset, SEEK_SET);
	if (!utils::WriteAll(write_fd, fec.data(), fec.size())) {
	PLOG(ERROR) << "EncodeFEC write() failed";
	return false;
	}
	}
	fec_offset += fec.size();
	}
	write_fd->Flush();
	return true;
	}

	bool VerityWriterAndroid::EncodeFEC(const std::string& path,
	uint64_t data_offset,
	uint64_t data_size,
	uint64_t fec_offset,
	uint64_t fec_size,
	uint32_t fec_roots,
	uint32_t block_size,
	bool verify_mode) {
	EintrSafeFileDescriptor fd;
	TEST_AND_RETURN_FALSE(fd.Open(path.c_str(), verify_mode ? O_RDONLY : O_RDWR));
	return EncodeFEC(&fd,
	&fd,
	data_offset,
	data_size,
	fec_offset,
	fec_size,
	fec_roots,
	block_size,
	verify_mode);
	}
	} // namespace chromeos_update_engine