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/*
* Copyright (C) 2007 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 "writer.h"
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
#include <string>
#include <android-base/file.h>
#include <android-base/unique_fd.h>
#include "reader.h"
#include "utility.h"
namespace android {
namespace fs_mgr {
std::string SerializeGeometry(const LpMetadataGeometry& input) {
LpMetadataGeometry geometry = input;
memset(geometry.checksum, 0, sizeof(geometry.checksum));
SHA256(&geometry, sizeof(geometry), geometry.checksum);
std::string blob(reinterpret_cast<const char*>(&geometry), sizeof(geometry));
blob.resize(LP_METADATA_GEOMETRY_SIZE);
return blob;
}
static bool CompareGeometry(const LpMetadataGeometry& g1, const LpMetadataGeometry& g2) {
return g1.metadata_max_size == g2.metadata_max_size &&
g1.metadata_slot_count == g2.metadata_slot_count &&
g1.logical_block_size == g2.logical_block_size;
}
std::string SerializeMetadata(const LpMetadata& input) {
LpMetadata metadata = input;
LpMetadataHeader& header = metadata.header;
// Serialize individual tables.
std::string partitions(reinterpret_cast<const char*>(metadata.partitions.data()),
metadata.partitions.size() * sizeof(LpMetadataPartition));
std::string extents(reinterpret_cast<const char*>(metadata.extents.data()),
metadata.extents.size() * sizeof(LpMetadataExtent));
std::string groups(reinterpret_cast<const char*>(metadata.groups.data()),
metadata.groups.size() * sizeof(LpMetadataPartitionGroup));
std::string block_devices(reinterpret_cast<const char*>(metadata.block_devices.data()),
metadata.block_devices.size() * sizeof(LpMetadataBlockDevice));
// Compute positions of tables.
header.partitions.offset = 0;
header.extents.offset = header.partitions.offset + partitions.size();
header.groups.offset = header.extents.offset + extents.size();
header.block_devices.offset = header.groups.offset + groups.size();
header.tables_size = header.block_devices.offset + block_devices.size();
// Compute payload checksum.
std::string tables = partitions + extents + groups + block_devices;
SHA256(tables.data(), tables.size(), header.tables_checksum);
// Compute header checksum.
memset(header.header_checksum, 0, sizeof(header.header_checksum));
SHA256(&header, header.header_size, header.header_checksum);
std::string header_blob =
std::string(reinterpret_cast<const char*>(&header), header.header_size);
return header_blob + tables;
}
// Perform checks so we don't accidentally overwrite valid metadata with
// potentially invalid metadata, or random partition data with metadata.
static bool ValidateAndSerializeMetadata([[maybe_unused]] const IPartitionOpener& opener,
const LpMetadata& metadata, const std::string& slot_suffix,
std::string* blob) {
const LpMetadataGeometry& geometry = metadata.geometry;
*blob = SerializeMetadata(metadata);
// Make sure we're writing within the space reserved.
if (blob->size() > geometry.metadata_max_size) {
LERROR << "Logical partition metadata is too large. " << blob->size() << " > "
<< geometry.metadata_max_size;
return false;
}
// Make sure the device has enough space to store two backup copies of the
// metadata.
uint64_t reserved_size = LP_METADATA_GEOMETRY_SIZE +
uint64_t(geometry.metadata_max_size) * geometry.metadata_slot_count;
uint64_t total_reserved = LP_PARTITION_RESERVED_BYTES + reserved_size * 2;
const LpMetadataBlockDevice* super_device = GetMetadataSuperBlockDevice(metadata);
if (!super_device) {
LERROR << "Logical partition metadata does not have a super block device.";
return false;
}
if (total_reserved > super_device->first_logical_sector * LP_SECTOR_SIZE) {
LERROR << "Not enough space to store all logical partition metadata slots.";
return false;
}
for (const auto& block_device : metadata.block_devices) {
std::string partition_name = GetBlockDevicePartitionName(block_device);
if (block_device.flags & LP_BLOCK_DEVICE_SLOT_SUFFIXED) {
if (slot_suffix.empty()) {
LERROR << "Block device " << partition_name << " requires a slot suffix,"
<< " which could not be derived from the super partition name.";
return false;
}
partition_name += slot_suffix;
}
if ((block_device.first_logical_sector + 1) * LP_SECTOR_SIZE > block_device.size) {
LERROR << "Block device " << partition_name << " has invalid first sector "
<< block_device.first_logical_sector << " for size " << block_device.size;
return false;
}
// When flashing on the device, check partition sizes. Don't do this on
// the host since there is no way to verify.
#if defined(__ANDROID__)
BlockDeviceInfo info;
if (!opener.GetInfo(partition_name, &info)) {
PERROR << partition_name << ": ioctl";
return false;
}
if (info.size != block_device.size) {
LERROR << "Block device " << partition_name << " size mismatch (expected"
<< block_device.size << ", got " << info.size << ")";
return false;
}
#endif
}
// Make sure all partition entries reference valid extents.
for (const auto& partition : metadata.partitions) {
if (partition.first_extent_index + partition.num_extents > metadata.extents.size()) {
LERROR << "Partition references invalid extent.";
return false;
}
}
// Make sure all linear extents have a valid range.
uint64_t last_sector = super_device->size / LP_SECTOR_SIZE;
for (const auto& extent : metadata.extents) {
if (extent.target_type == LP_TARGET_TYPE_LINEAR) {
uint64_t physical_sector = extent.target_data;
if (physical_sector < super_device->first_logical_sector ||
physical_sector + extent.num_sectors > last_sector) {
LERROR << "Extent table entry is out of bounds.";
return false;
}
}
}
return true;
}
// Check that the given region is within metadata bounds.
static bool ValidateMetadataRegion(const LpMetadata& metadata, uint64_t start, size_t size) {
const LpMetadataBlockDevice* super_device = GetMetadataSuperBlockDevice(metadata);
if (!super_device) {
LERROR << __PRETTY_FUNCTION__ << " could not locate super block device in metadata";
return false;
}
if (start + size >= super_device->first_logical_sector * LP_SECTOR_SIZE) {
LERROR << __PRETTY_FUNCTION__ << " write of " << size << " bytes at " << start
<< " overlaps with logical partition contents";
return false;
}
return true;
}
static bool WritePrimaryMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
const std::string& blob,
const std::function<bool(int, const std::string&)>& writer) {
int64_t primary_offset = GetPrimaryMetadataOffset(metadata.geometry, slot_number);
if (!ValidateMetadataRegion(metadata, primary_offset, blob.size())) {
return false;
}
if (SeekFile64(fd, primary_offset, SEEK_SET) < 0) {
PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset " << primary_offset;
return false;
}
if (!writer(fd, blob)) {
PERROR << __PRETTY_FUNCTION__ << " write " << blob.size() << " bytes failed";
return false;
}
return true;
}
static bool WriteBackupMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
const std::string& blob,
const std::function<bool(int, const std::string&)>& writer) {
int64_t backup_offset = GetBackupMetadataOffset(metadata.geometry, slot_number);
if (!ValidateMetadataRegion(metadata, backup_offset, blob.size())) {
return false;
}
if (SeekFile64(fd, backup_offset, SEEK_SET) < 0) {
PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset " << backup_offset;
return false;
}
if (!writer(fd, blob)) {
PERROR << __PRETTY_FUNCTION__ << " backup write " << blob.size() << " bytes failed";
return false;
}
return true;
}
static bool WriteMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
const std::string& blob,
const std::function<bool(int, const std::string&)>& writer) {
// Make sure we're writing to a valid metadata slot.
if (slot_number >= metadata.geometry.metadata_slot_count) {
LERROR << "Invalid logical partition metadata slot number.";
return false;
}
if (!WritePrimaryMetadata(fd, metadata, slot_number, blob, writer)) {
return false;
}
if (!WriteBackupMetadata(fd, metadata, slot_number, blob, writer)) {
return false;
}
return true;
}
static bool DefaultWriter(int fd, const std::string& blob) {
return android::base::WriteFully(fd, blob.data(), blob.size());
}
#if defined(_WIN32)
static const int O_SYNC = 0;
#endif
bool FlashPartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
const LpMetadata& metadata) {
android::base::unique_fd fd = opener.Open(super_partition, O_RDWR | O_SYNC);
if (fd < 0) {
PERROR << __PRETTY_FUNCTION__ << " open failed: " << super_partition;
return false;
}
// This is only used in update_engine and fastbootd, where the super
// partition should be specified as a name (or by-name link), and
// therefore, we should be able to extract a slot suffix.
std::string slot_suffix = GetPartitionSlotSuffix(super_partition);
// Before writing geometry and/or logical partition tables, perform some
// basic checks that the geometry and tables are coherent, and will fit
// on the given block device.
std::string metadata_blob;
if (!ValidateAndSerializeMetadata(opener, metadata, slot_suffix, &metadata_blob)) {
return false;
}
// On retrofit devices, super_partition is system_other and might be set to readonly by
// fs_mgr_set_blk_ro(). Unset readonly so that fd can be written to.
if (!SetBlockReadonly(fd.get(), false)) {
PWARNING << __PRETTY_FUNCTION__ << " BLKROSET 0 failed: " << super_partition;
}
// Write zeroes to the first block.
std::string zeroes(LP_PARTITION_RESERVED_BYTES, 0);
if (SeekFile64(fd, 0, SEEK_SET) < 0) {
PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset 0";
return false;
}
if (!android::base::WriteFully(fd, zeroes.data(), zeroes.size())) {
PERROR << __PRETTY_FUNCTION__ << " write " << zeroes.size() << " bytes failed";
return false;
}
LWARN << "Flashing new logical partition geometry to " << super_partition;
// Write geometry to the primary and backup locations.
std::string blob = SerializeGeometry(metadata.geometry);
if (SeekFile64(fd, GetPrimaryGeometryOffset(), SEEK_SET) < 0) {
PERROR << __PRETTY_FUNCTION__ << " lseek failed: primary geometry";
return false;
}
if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
PERROR << __PRETTY_FUNCTION__ << " write " << blob.size() << " bytes failed";
return false;
}
if (SeekFile64(fd, GetBackupGeometryOffset(), SEEK_SET) < 0) {
PERROR << __PRETTY_FUNCTION__ << " lseek failed: backup geometry";
return false;
}
if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
PERROR << __PRETTY_FUNCTION__ << " backup write " << blob.size() << " bytes failed";
return false;
}
bool ok = true;
for (size_t i = 0; i < metadata.geometry.metadata_slot_count; i++) {
ok &= WriteMetadata(fd, metadata, i, metadata_blob, DefaultWriter);
}
return ok;
}
bool FlashPartitionTable(const std::string& super_partition, const LpMetadata& metadata) {
return FlashPartitionTable(PartitionOpener(), super_partition, metadata);
}
static bool CompareMetadata(const LpMetadata& a, const LpMetadata& b) {
return !memcmp(a.header.header_checksum, b.header.header_checksum,
sizeof(a.header.header_checksum));
}
bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
const LpMetadata& metadata, uint32_t slot_number,
const std::function<bool(int, const std::string&)>& writer) {
android::base::unique_fd fd = opener.Open(super_partition, O_RDWR | O_SYNC);
if (fd < 0) {
PERROR << __PRETTY_FUNCTION__ << " open failed: " << super_partition;
return false;
}
std::string slot_suffix = SlotSuffixForSlotNumber(slot_number);
// Before writing geometry and/or logical partition tables, perform some
// basic checks that the geometry and tables are coherent, and will fit
// on the given block device.
std::string blob;
if (!ValidateAndSerializeMetadata(opener, metadata, slot_suffix, &blob)) {
return false;
}
// Verify that the old geometry is identical. If it's not, then we might be
// writing a table that was built for a different device, so we must reject
// it.
const LpMetadataGeometry& geometry = metadata.geometry;
LpMetadataGeometry old_geometry;
if (!ReadLogicalPartitionGeometry(fd, &old_geometry)) {
return false;
}
if (!CompareGeometry(geometry, old_geometry)) {
LERROR << "Incompatible geometry in new logical partition metadata";
return false;
}
// Validate the slot number now, before we call Read*Metadata.
if (slot_number >= geometry.metadata_slot_count) {
LERROR << "Invalid logical partition metadata slot number.";
return false;
}
// Try to read both existing copies of the metadata, if any.
std::unique_ptr<LpMetadata> primary = ReadPrimaryMetadata(fd, geometry, slot_number);
std::unique_ptr<LpMetadata> backup = ReadBackupMetadata(fd, geometry, slot_number);
if (primary && (!backup || !CompareMetadata(*primary.get(), *backup.get()))) {
// If the backup copy does not match the primary copy, we first
// synchronize the backup copy. This guarantees that a partial write
// still leaves one copy intact.
std::string old_blob;
if (!ValidateAndSerializeMetadata(opener, *primary.get(), slot_suffix, &old_blob)) {
LERROR << "Error serializing primary metadata to repair corrupted backup";
return false;
}
if (!WriteBackupMetadata(fd, metadata, slot_number, old_blob, writer)) {
LERROR << "Error writing primary metadata to repair corrupted backup";
return false;
}
} else if (backup && !primary) {
// The backup copy is coherent, and the primary is not. Sync it for
// safety.
std::string old_blob;
if (!ValidateAndSerializeMetadata(opener, *backup.get(), slot_suffix, &old_blob)) {
LERROR << "Error serializing backup metadata to repair corrupted primary";
return false;
}
if (!WritePrimaryMetadata(fd, metadata, slot_number, old_blob, writer)) {
LERROR << "Error writing backup metadata to repair corrupted primary";
return false;
}
}
// Both copies should now be in sync, so we can continue the update.
if (!WriteMetadata(fd, metadata, slot_number, blob, writer)) {
return false;
}
LINFO << "Updated logical partition table at slot " << slot_number << " on device "
<< super_partition;
return true;
}
bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
const LpMetadata& metadata, uint32_t slot_number) {
return UpdatePartitionTable(opener, super_partition, metadata, slot_number, DefaultWriter);
}
bool UpdatePartitionTable(const std::string& super_partition, const LpMetadata& metadata,
uint32_t slot_number) {
PartitionOpener opener;
return UpdatePartitionTable(opener, super_partition, metadata, slot_number, DefaultWriter);
}
} // namespace fs_mgr
} // namespace android