fs_mgr: Add a library for managing logical partitions.
This library has methods to build, read, and modify logical partition tables
based on device-mapper targets. Targets currently supported are
dm-linear and dm-zero.
Bug: 79173901
Test: N/A
Change-Id: I194c6832cb53f781c396016d961386d3ca833f87
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index 923442f..b0b4839 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -57,12 +57,15 @@
"libavb",
"libfstab",
"libdm",
+ "liblp",
],
export_static_lib_headers: [
"libfstab",
"libdm",
+ "liblp",
],
whole_static_libs: [
+ "liblp",
"liblogwrap",
"libdm",
"libfstab",
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
new file mode 100644
index 0000000..d7bc6b5
--- /dev/null
+++ b/fs_mgr/liblp/Android.bp
@@ -0,0 +1,38 @@
+//
+// 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.
+//
+
+cc_library_static {
+ name: "liblp",
+ host_supported: true,
+ recovery_available: true,
+ defaults: ["fs_mgr_defaults"],
+ srcs: [
+ "builder.cpp",
+ "reader.cpp",
+ "utility.cpp",
+ "writer.cpp",
+ ],
+ static_libs: [
+ "libbase",
+ "liblog",
+ "libcrypto",
+ "libcrypto_utils",
+ ],
+ whole_static_libs: [
+ "libext2_uuid",
+ ],
+ export_include_dirs: ["include"],
+}
diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
new file mode 100644
index 0000000..bfbf3e5
--- /dev/null
+++ b/fs_mgr/liblp/builder.cpp
@@ -0,0 +1,352 @@
+/*
+ * 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 "liblp/builder.h"
+
+#include <string.h>
+
+#include <algorithm>
+
+#include <android-base/endian.h>
+#include <uuid/uuid.h>
+
+#include "liblp/metadata_format.h"
+#include "utility.h"
+
+namespace android {
+namespace fs_mgr {
+
+// Align a byte count up to the nearest 512-byte sector.
+template <typename T>
+static inline T AlignToSector(T value) {
+ return (value + (LP_SECTOR_SIZE - 1)) & ~T(LP_SECTOR_SIZE - 1);
+}
+
+void LinearExtent::AddTo(LpMetadata* out) const {
+ out->extents.push_back(LpMetadataExtent{num_sectors_, LP_TARGET_TYPE_LINEAR, physical_sector_});
+}
+
+void ZeroExtent::AddTo(LpMetadata* out) const {
+ out->extents.push_back(LpMetadataExtent{num_sectors_, LP_TARGET_TYPE_ZERO, 0});
+}
+
+Partition::Partition(const std::string& name, const std::string& guid, uint32_t attributes)
+ : name_(name), guid_(guid), attributes_(attributes), size_(0) {}
+
+void Partition::AddExtent(std::unique_ptr<Extent>&& extent) {
+ size_ += extent->num_sectors() * LP_SECTOR_SIZE;
+ extents_.push_back(std::move(extent));
+}
+
+void Partition::RemoveExtents() {
+ size_ = 0;
+ extents_.clear();
+}
+
+void Partition::ShrinkTo(uint64_t requested_size) {
+ uint64_t aligned_size = AlignToSector(requested_size);
+ if (size_ <= aligned_size) {
+ return;
+ }
+ if (aligned_size == 0) {
+ RemoveExtents();
+ return;
+ }
+
+ // Remove or shrink extents of any kind until the total partition size is
+ // equal to the requested size.
+ uint64_t sectors_to_remove = (size_ - aligned_size) / LP_SECTOR_SIZE;
+ while (sectors_to_remove) {
+ Extent* extent = extents_.back().get();
+ if (extent->num_sectors() > sectors_to_remove) {
+ size_ -= sectors_to_remove * LP_SECTOR_SIZE;
+ extent->set_num_sectors(extent->num_sectors() - sectors_to_remove);
+ break;
+ }
+ size_ -= (extent->num_sectors() * LP_SECTOR_SIZE);
+ sectors_to_remove -= extent->num_sectors();
+ extents_.pop_back();
+ }
+ DCHECK(size_ == requested_size);
+}
+
+std::unique_ptr<MetadataBuilder> MetadataBuilder::New(uint64_t blockdevice_size,
+ uint32_t metadata_max_size,
+ uint32_t metadata_slot_count) {
+ std::unique_ptr<MetadataBuilder> builder(new MetadataBuilder());
+ if (!builder->Init(blockdevice_size, metadata_max_size, metadata_slot_count)) {
+ return nullptr;
+ }
+ return builder;
+}
+
+std::unique_ptr<MetadataBuilder> MetadataBuilder::New(const LpMetadata& metadata) {
+ std::unique_ptr<MetadataBuilder> builder(new MetadataBuilder());
+ if (!builder->Init(metadata)) {
+ return nullptr;
+ }
+ return builder;
+}
+
+MetadataBuilder::MetadataBuilder() {
+ memset(&geometry_, 0, sizeof(geometry_));
+ geometry_.magic = LP_METADATA_GEOMETRY_MAGIC;
+ geometry_.struct_size = sizeof(geometry_);
+
+ memset(&header_, 0, sizeof(header_));
+ header_.magic = LP_METADATA_HEADER_MAGIC;
+ header_.major_version = LP_METADATA_MAJOR_VERSION;
+ header_.minor_version = LP_METADATA_MINOR_VERSION;
+ header_.header_size = sizeof(header_);
+ header_.partitions.entry_size = sizeof(LpMetadataPartition);
+ header_.extents.entry_size = sizeof(LpMetadataExtent);
+}
+
+bool MetadataBuilder::Init(const LpMetadata& metadata) {
+ geometry_ = metadata.geometry;
+
+ for (const auto& partition : metadata.partitions) {
+ Partition* builder = AddPartition(GetPartitionName(partition), GetPartitionGuid(partition),
+ partition.attributes);
+ if (!builder) {
+ return false;
+ }
+
+ for (size_t i = 0; i < partition.num_extents; i++) {
+ const LpMetadataExtent& extent = metadata.extents[partition.first_extent_index + i];
+ if (extent.target_type == LP_TARGET_TYPE_LINEAR) {
+ auto copy = std::make_unique<LinearExtent>(extent.num_sectors, extent.target_data);
+ builder->AddExtent(std::move(copy));
+ } else if (extent.target_type == LP_TARGET_TYPE_ZERO) {
+ auto copy = std::make_unique<ZeroExtent>(extent.num_sectors);
+ builder->AddExtent(std::move(copy));
+ }
+ }
+ }
+ return true;
+}
+
+bool MetadataBuilder::Init(uint64_t blockdevice_size, uint32_t metadata_max_size,
+ uint32_t metadata_slot_count) {
+ if (metadata_max_size < sizeof(LpMetadataHeader)) {
+ LERROR << "Invalid metadata maximum size.";
+ return false;
+ }
+ if (metadata_slot_count == 0) {
+ LERROR << "Invalid metadata slot count.";
+ return false;
+ }
+
+ // Align the metadata size up to the nearest sector.
+ metadata_max_size = AlignToSector(metadata_max_size);
+
+ // We reserve a geometry block (4KB) plus space for each copy of the
+ // maximum size of a metadata blob. Then, we double that space since
+ // we store a backup copy of everything.
+ uint64_t reserved =
+ LP_METADATA_GEOMETRY_SIZE + (uint64_t(metadata_max_size) * metadata_slot_count);
+ uint64_t total_reserved = reserved * 2;
+
+ if (blockdevice_size < total_reserved || blockdevice_size - total_reserved < LP_SECTOR_SIZE) {
+ LERROR << "Attempting to create metadata on a block device that is too small.";
+ return false;
+ }
+
+ // The last sector is inclusive. We subtract one to make sure that logical
+ // partitions won't overlap with the same sector as the backup metadata,
+ // which could happen if the block device was not aligned to LP_SECTOR_SIZE.
+ geometry_.first_logical_sector = reserved / LP_SECTOR_SIZE;
+ geometry_.last_logical_sector = ((blockdevice_size - reserved) / LP_SECTOR_SIZE) - 1;
+ geometry_.metadata_max_size = metadata_max_size;
+ geometry_.metadata_slot_count = metadata_slot_count;
+ DCHECK(geometry_.last_logical_sector >= geometry_.first_logical_sector);
+ return true;
+}
+
+Partition* MetadataBuilder::AddPartition(const std::string& name, const std::string& guid,
+ uint32_t attributes) {
+ if (name.empty()) {
+ LERROR << "Partition must have a non-empty name.";
+ return nullptr;
+ }
+ if (FindPartition(name)) {
+ LERROR << "Attempting to create duplication partition with name: " << name;
+ return nullptr;
+ }
+ partitions_.push_back(std::make_unique<Partition>(name, guid, attributes));
+ return partitions_.back().get();
+}
+
+Partition* MetadataBuilder::FindPartition(const std::string& name) {
+ for (const auto& partition : partitions_) {
+ if (partition->name() == name) {
+ return partition.get();
+ }
+ }
+ return nullptr;
+}
+
+void MetadataBuilder::RemovePartition(const std::string& name) {
+ for (auto iter = partitions_.begin(); iter != partitions_.end(); iter++) {
+ if ((*iter)->name() == name) {
+ partitions_.erase(iter);
+ return;
+ }
+ }
+}
+
+bool MetadataBuilder::GrowPartition(Partition* partition, uint64_t requested_size) {
+ // Align the space needed up to the nearest sector.
+ uint64_t aligned_size = AlignToSector(requested_size);
+ if (partition->size() >= aligned_size) {
+ return true;
+ }
+
+ // Figure out how much we need to allocate.
+ uint64_t space_needed = aligned_size - partition->size();
+ uint64_t sectors_needed = space_needed / LP_SECTOR_SIZE;
+ DCHECK(sectors_needed * LP_SECTOR_SIZE == space_needed);
+
+ struct Interval {
+ uint64_t start;
+ uint64_t end;
+
+ Interval(uint64_t start, uint64_t end) : start(start), end(end) {}
+ bool operator<(const Interval& other) const { return start < other.start; }
+ };
+ std::vector<Interval> intervals;
+
+ // Collect all extents in the partition table.
+ for (const auto& partition : partitions_) {
+ for (const auto& extent : partition->extents()) {
+ LinearExtent* linear = extent->AsLinearExtent();
+ if (!linear) {
+ continue;
+ }
+ intervals.emplace_back(linear->physical_sector(),
+ linear->physical_sector() + extent->num_sectors());
+ }
+ }
+
+ // Sort extents by starting sector.
+ std::sort(intervals.begin(), intervals.end());
+
+ // Find gaps that we can use for new extents. Note we store new extents in a
+ // temporary vector, and only commit them if we are guaranteed enough free
+ // space.
+ std::vector<std::unique_ptr<LinearExtent>> new_extents;
+ for (size_t i = 1; i < intervals.size(); i++) {
+ const Interval& previous = intervals[i - 1];
+ const Interval& current = intervals[i];
+
+ if (previous.end >= current.start) {
+ // There is no gap between these two extents, try the next one. Note that
+ // extents may never overlap, but just for safety, we ignore them if they
+ // do.
+ DCHECK(previous.end == current.start);
+ continue;
+ }
+
+ // This gap is enough to hold the remainder of the space requested, so we
+ // can allocate what we need and return.
+ if (current.start - previous.end >= sectors_needed) {
+ auto extent = std::make_unique<LinearExtent>(sectors_needed, previous.end);
+ sectors_needed -= extent->num_sectors();
+ new_extents.push_back(std::move(extent));
+ break;
+ }
+
+ // This gap is not big enough to fit the remainder of the space requested,
+ // so consume the whole thing and keep looking for more.
+ auto extent = std::make_unique<LinearExtent>(current.start - previous.end, previous.end);
+ sectors_needed -= extent->num_sectors();
+ new_extents.push_back(std::move(extent));
+ }
+
+ // If we still have more to allocate, take it from the remaining free space
+ // in the allocatable region.
+ if (sectors_needed) {
+ uint64_t first_sector;
+ if (intervals.empty()) {
+ first_sector = geometry_.first_logical_sector;
+ } else {
+ first_sector = intervals.back().end;
+ }
+ DCHECK(first_sector <= geometry_.last_logical_sector);
+
+ // Note: the last usable sector is inclusive.
+ if (first_sector + sectors_needed > geometry_.last_logical_sector) {
+ LERROR << "Not enough free space to expand partition: " << partition->name();
+ return false;
+ }
+ auto extent = std::make_unique<LinearExtent>(sectors_needed, first_sector);
+ new_extents.push_back(std::move(extent));
+ }
+
+ for (auto& extent : new_extents) {
+ partition->AddExtent(std::move(extent));
+ }
+ return true;
+}
+
+void MetadataBuilder::ShrinkPartition(Partition* partition, uint64_t requested_size) {
+ partition->ShrinkTo(requested_size);
+}
+
+std::unique_ptr<LpMetadata> MetadataBuilder::Export() {
+ std::unique_ptr<LpMetadata> metadata = std::make_unique<LpMetadata>();
+ metadata->header = header_;
+ metadata->geometry = geometry_;
+
+ // Flatten the partition and extent structures into an LpMetadata, which
+ // makes it very easy to validate, serialize, or pass on to device-mapper.
+ for (const auto& partition : partitions_) {
+ LpMetadataPartition part;
+ memset(&part, 0, sizeof(part));
+
+ if (partition->name().size() > sizeof(part.name)) {
+ LERROR << "Partition name is too long: " << partition->name();
+ return nullptr;
+ }
+ if (partition->attributes() & ~(LP_PARTITION_ATTRIBUTE_MASK)) {
+ LERROR << "Partition " << partition->name() << " has unsupported attribute.";
+ return nullptr;
+ }
+
+ strncpy(part.name, partition->name().c_str(), sizeof(part.name));
+ if (uuid_parse(partition->guid().c_str(), part.guid) != 0) {
+ LERROR << "Could not parse guid " << partition->guid() << " for partition "
+ << partition->name();
+ return nullptr;
+ }
+
+ part.first_extent_index = static_cast<uint32_t>(metadata->extents.size());
+ part.num_extents = static_cast<uint32_t>(partition->extents().size());
+ part.attributes = partition->attributes();
+
+ for (const auto& extent : partition->extents()) {
+ extent->AddTo(metadata.get());
+ }
+ metadata->partitions.push_back(part);
+ }
+
+ metadata->header.partitions.num_entries = static_cast<uint32_t>(metadata->partitions.size());
+ metadata->header.extents.num_entries = static_cast<uint32_t>(metadata->extents.size());
+ return metadata;
+}
+
+} // namespace fs_mgr
+} // namespace android
diff --git a/fs_mgr/liblp/include/liblp/builder.h b/fs_mgr/liblp/include/liblp/builder.h
new file mode 100644
index 0000000..fb982e2
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/builder.h
@@ -0,0 +1,169 @@
+//
+// 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.
+//
+
+#ifndef LIBLP_METADATA_BUILDER_H
+#define LIBLP_METADATA_BUILDER_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <map>
+#include <memory>
+
+#include "metadata_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+class LinearExtent;
+
+// Abstraction around dm-targets that can be encoded into logical partition tables.
+class Extent {
+ public:
+ explicit Extent(uint64_t num_sectors) : num_sectors_(num_sectors) {}
+ virtual ~Extent() {}
+
+ virtual void AddTo(LpMetadata* out) const = 0;
+ virtual LinearExtent* AsLinearExtent() { return nullptr; }
+
+ uint64_t num_sectors() const { return num_sectors_; }
+ void set_num_sectors(uint64_t num_sectors) { num_sectors_ = num_sectors; }
+
+ protected:
+ uint64_t num_sectors_;
+};
+
+// This corresponds to a dm-linear target.
+class LinearExtent final : public Extent {
+ public:
+ LinearExtent(uint64_t num_sectors, uint64_t physical_sector)
+ : Extent(num_sectors), physical_sector_(physical_sector) {}
+
+ void AddTo(LpMetadata* metadata) const override;
+ LinearExtent* AsLinearExtent() override { return this; }
+
+ uint64_t physical_sector() const { return physical_sector_; }
+
+ private:
+ uint64_t physical_sector_;
+};
+
+// This corresponds to a dm-zero target.
+class ZeroExtent final : public Extent {
+ public:
+ explicit ZeroExtent(uint64_t num_sectors) : Extent(num_sectors) {}
+
+ void AddTo(LpMetadata* out) const override;
+};
+
+class Partition final {
+ public:
+ Partition(const std::string& name, const std::string& guid, uint32_t attributes);
+
+ // Add a raw extent.
+ void AddExtent(std::unique_ptr<Extent>&& extent);
+
+ // Remove all extents from this partition.
+ void RemoveExtents();
+
+ // Remove and/or shrink extents until the partition is the requested size.
+ // See MetadataBuilder::ShrinkPartition for more information.
+ void ShrinkTo(uint64_t requested_size);
+
+ const std::string& name() const { return name_; }
+ uint32_t attributes() const { return attributes_; }
+ const std::string& guid() const { return guid_; }
+ const std::vector<std::unique_ptr<Extent>>& extents() const { return extents_; }
+ uint64_t size() const { return size_; }
+
+ private:
+ std::string name_;
+ std::string guid_;
+ std::vector<std::unique_ptr<Extent>> extents_;
+ uint32_t attributes_;
+ uint64_t size_;
+};
+
+class MetadataBuilder {
+ public:
+ // Construct an empty logical partition table builder. The block device size
+ // and maximum metadata size must be specified, as this will determine which
+ // areas of the physical partition can be flashed for metadata vs for logical
+ // partitions.
+ //
+ // If the parameters would yield invalid metadata, nullptr is returned. This
+ // could happen if the block device size is too small to store the metadata
+ // and backup copies.
+ static std::unique_ptr<MetadataBuilder> New(uint64_t blockdevice_size,
+ uint32_t metadata_max_size,
+ uint32_t metadata_slot_count);
+
+ // Import an existing table for modification. If the table is not valid, for
+ // example it contains duplicate partition names, then nullptr is returned.
+ static std::unique_ptr<MetadataBuilder> New(const LpMetadata& metadata);
+
+ // Export metadata so it can be serialized to an image, to disk, or mounted
+ // via device-mapper.
+ std::unique_ptr<LpMetadata> Export();
+
+ // Add a partition, returning a handle so it can be sized as needed. If a
+ // partition with the given name already exists, nullptr is returned.
+ Partition* AddPartition(const std::string& name, const std::string& guid, uint32_t attributes);
+
+ // Delete a partition by name if it exists.
+ void RemovePartition(const std::string& name);
+
+ // Find a partition by name. If no partition is found, nullptr is returned.
+ Partition* FindPartition(const std::string& name);
+
+ // Grow a partition to the requested size. If the partition's size is already
+ // greater or equal to the requested size, this will return true and the
+ // partition table will not be changed. Otherwise, a greedy algorithm is
+ // used to find free gaps in the partition table and allocate them for this
+ // partition. If not enough space can be allocated, false is returned, and
+ // the parition table will not be modified.
+ //
+ // The size will be rounded UP to the nearest sector.
+ //
+ // Note, this is an in-memory operation, and it does not alter the
+ // underlying filesystem or contents of the partition on disk.
+ bool GrowPartition(Partition* partition, uint64_t requested_size);
+
+ // Shrink a partition to the requested size. If the partition is already
+ // smaller than the given size, this will return and the partition table
+ // will not be changed. Otherwise, extents will be removed and/or shrunk
+ // from the end of the partition until it is the requested size.
+ //
+ // The size will be rounded UP to the nearest sector.
+ //
+ // Note, this is an in-memory operation, and it does not alter the
+ // underlying filesystem or contents of the partition on disk.
+ void ShrinkPartition(Partition* partition, uint64_t requested_size);
+
+ private:
+ MetadataBuilder();
+ bool Init(uint64_t blockdevice_size, uint32_t metadata_max_size, uint32_t metadata_slot_count);
+ bool Init(const LpMetadata& metadata);
+
+ LpMetadataGeometry geometry_;
+ LpMetadataHeader header_;
+ std::vector<std::unique_ptr<Partition>> partitions_;
+};
+
+} // namespace fs_mgr
+} // namespace android
+
+#endif /* LIBLP_METADATA_BUILDER_H */
diff --git a/fs_mgr/liblp/include/liblp/metadata_format.h b/fs_mgr/liblp/include/liblp/metadata_format.h
new file mode 100644
index 0000000..f6262ff
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/metadata_format.h
@@ -0,0 +1,263 @@
+/*
+ * 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.
+ */
+
+#ifndef LOGICAL_PARTITION_METADATA_FORMAT_H_
+#define LOGICAL_PARTITION_METADATA_FORMAT_H_
+
+#ifdef __cplusplus
+#include <string>
+#include <vector>
+#endif
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Magic signature for LpMetadataGeometry. */
+#define LP_METADATA_GEOMETRY_MAGIC 0x616c4467
+
+/* Space reserved for geometry information. */
+#define LP_METADATA_GEOMETRY_SIZE 4096
+
+/* Magic signature for LpMetadataHeader. */
+#define LP_METADATA_HEADER_MAGIC 0x414C5030
+
+/* Current metadata version. */
+#define LP_METADATA_MAJOR_VERSION 1
+#define LP_METADATA_MINOR_VERSION 0
+
+/* Attributes for the LpMetadataPartition::attributes field.
+ *
+ * READONLY - The partition should not be considered writable. When used with
+ * device mapper, the block device will be created as read-only.
+ */
+#define LP_PARTITION_ATTR_READONLY 0x1
+
+/* Mask that defines all valid attributes. */
+#define LP_PARTITION_ATTRIBUTE_MASK (LP_PARTITION_ATTR_READONLY)
+
+/* Default name of the physical partition that holds logical partition entries.
+ * The layout of this partition will look like:
+ *
+ * +--------------------+
+ * | Disk Geometry |
+ * +--------------------+
+ * | Metadata |
+ * +--------------------+
+ * | Logical Partitions |
+ * +--------------------+
+ * | Backup Metadata |
+ * +--------------------+
+ * | Geometry Backup |
+ * +--------------------+
+ */
+#define LP_METADATA_PARTITION_NAME "android"
+
+/* Size of a sector is always 512 bytes for compatibility with the Linux kernel. */
+#define LP_SECTOR_SIZE 512
+
+/* This structure is stored at sector 0 in the first 4096 bytes of the
+ * partition, and again in the very last 4096 bytes. It is never modified and
+ * describes how logical partition information can be located.
+ */
+typedef struct LpMetadataGeometry {
+ /* 0: Magic signature (LP_METADATA_GEOMETRY_MAGIC). */
+ uint32_t magic;
+
+ /* 4: Size of the LpMetadataGeometry struct. */
+ uint32_t struct_size;
+
+ /* 8: SHA256 checksum of this struct, with this field set to 0. */
+ uint8_t checksum[32];
+
+ /* 40: Maximum amount of space a single copy of the metadata can use. */
+ uint32_t metadata_max_size;
+
+ /* 44: Number of copies of the metadata to keep. For A/B devices, this
+ * will be 2. For an A/B/C device, it would be 3, et cetera. For Non-A/B
+ * it will be 1. A backup copy of each slot is kept, so if this is "2",
+ * there will be four copies total.
+ */
+ uint32_t metadata_slot_count;
+
+ /* 48: First usable sector for allocating logical partitions. this will be
+ * the first sector after the initial 4096 geometry block, followed by the
+ * space consumed by metadata_max_size*metadata_slot_count.
+ */
+ uint64_t first_logical_sector;
+
+ /* 56: Last usable sector, inclusive, for allocating logical partitions.
+ * At the end of this sector will follow backup metadata slots and the
+ * backup geometry block at the very end.
+ */
+ uint64_t last_logical_sector;
+} __attribute__((packed)) LpMetadataGeometry;
+
+/* The logical partition metadata has a number of tables; they are described
+ * in the header via the following structure.
+ *
+ * The size of the table can be computed by multiplying entry_size by
+ * num_entries, and the result must not overflow a 32-bit signed integer.
+ */
+typedef struct LpMetadataTableDescriptor {
+ /* 0: Location of the table, relative to the metadata header. */
+ uint32_t offset;
+ /* 4: Number of entries in the table. */
+ uint32_t num_entries;
+ /* 8: Size of each entry in the table, in bytes. */
+ uint32_t entry_size;
+} __attribute__((packed)) LpMetadataTableDescriptor;
+
+/* Binary format for the header of the logical partition metadata format.
+ *
+ * The format has three sections. The header must occur first, and the
+ * proceeding tables may be placed in any order after.
+ *
+ * +-----------------------------------------+
+ * | Header data - fixed size |
+ * +-----------------------------------------+
+ * | Partition table - variable size |
+ * +-----------------------------------------+
+ * | Partition table extents - variable size |
+ * +-----------------------------------------+
+ *
+ * The "Header" portion is described by LpMetadataHeader. It will always
+ * precede the other three blocks.
+ *
+ * All fields are stored in little-endian byte order when serialized.
+ *
+ * This struct is versioned; see the |major_version| and |minor_version|
+ * fields.
+ */
+typedef struct LpMetadataHeader {
+ /* 0: Four bytes equal to LP_METADATA_HEADER_MAGIC. */
+ uint32_t magic;
+
+ /* 4: Version number required to read this metadata. If the version is not
+ * equal to the library version, the metadata should be considered
+ * incompatible.
+ */
+ uint16_t major_version;
+
+ /* 6: Minor version. A library supporting newer features should be able to
+ * read metadata with an older minor version. However, an older library
+ * should not support reading metadata if its minor version is higher.
+ */
+ uint16_t minor_version;
+
+ /* 8: The size of this header struct. */
+ uint32_t header_size;
+
+ /* 12: SHA256 checksum of the header, up to |header_size| bytes, computed as
+ * if this field were set to 0.
+ */
+ uint8_t header_checksum[32];
+
+ /* 44: The total size of all tables. This size is contiguous; tables may not
+ * have gaps in between, and they immediately follow the header.
+ */
+ uint32_t tables_size;
+
+ /* 48: SHA256 checksum of all table contents. */
+ uint8_t tables_checksum[32];
+
+ /* 80: Partition table descriptor. */
+ LpMetadataTableDescriptor partitions;
+ /* 92: Extent table descriptor. */
+ LpMetadataTableDescriptor extents;
+} __attribute__((packed)) LpMetadataHeader;
+
+/* This struct defines a logical partition entry, similar to what would be
+ * present in a GUID Partition Table.
+ */
+typedef struct LpMetadataPartition {
+ /* 0: Name of this partition in ASCII characters. Any unused characters in
+ * the buffer must be set to 0. Characters may only be alphanumeric or _.
+ * The name must include at least one ASCII character, and it must be unique
+ * across all partition names. The length (36) is the same as the maximum
+ * length of a GPT partition name.
+ */
+ char name[36];
+
+ /* 36: Globally unique identifier (GUID) of this partition. */
+ uint8_t guid[16];
+
+ /* 52: Attributes for the partition (see LP_PARTITION_ATTR_* flags above). */
+ uint32_t attributes;
+
+ /* 56: Index of the first extent owned by this partition. The extent will
+ * start at logical sector 0. Gaps between extents are not allowed.
+ */
+ uint32_t first_extent_index;
+
+ /* 60: Number of extents in the partition. Every partition must have at
+ * least one extent.
+ */
+ uint32_t num_extents;
+} __attribute__((packed)) LpMetadataPartition;
+
+/* This extent is a dm-linear target, and the index is an index into the
+ * LinearExtent table.
+ */
+#define LP_TARGET_TYPE_LINEAR 0
+
+/* This extent is a dm-zero target. The index is ignored and must be 0. */
+#define LP_TARGET_TYPE_ZERO 1
+
+/* This struct defines an extent entry in the extent table block. */
+typedef struct LpMetadataExtent {
+ /* 0: Length of this extent, in 512-byte sectors. */
+ uint64_t num_sectors;
+
+ /* 8: Target type for device-mapper (see LP_TARGET_TYPE_* values). */
+ uint32_t target_type;
+
+ /* 12: Contents depends on target_type.
+ *
+ * LINEAR: The sector on the physical partition that this extent maps onto.
+ * ZERO: This field must be 0.
+ */
+ uint64_t target_data;
+} __attribute__((packed)) LpMetadataExtent;
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#ifdef __cplusplus
+namespace android {
+namespace fs_mgr {
+
+// Helper structure for easily interpreting deserialized metadata, or
+// re-serializing metadata.
+struct LpMetadata {
+ LpMetadataGeometry geometry;
+ LpMetadataHeader header;
+ std::vector<LpMetadataPartition> partitions;
+ std::vector<LpMetadataExtent> extents;
+};
+
+// Helper to extract safe C++ strings from partition info.
+std::string GetPartitionName(const LpMetadataPartition& partition);
+std::string GetPartitionGuid(const LpMetadataPartition& partition);
+
+} // namespace fs_mgr
+} // namespace android
+#endif
+
+#endif /* LOGICAL_PARTITION_METADATA_FORMAT_H_ */
diff --git a/fs_mgr/liblp/include/liblp/reader.h b/fs_mgr/liblp/include/liblp/reader.h
new file mode 100644
index 0000000..e7fa46d
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/reader.h
@@ -0,0 +1,43 @@
+/*
+ * 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.
+ */
+
+#ifndef LIBLP_READER_H_
+#define LIBLP_READER_H_
+
+#include <stddef.h>
+
+#include <memory>
+
+#include "metadata_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+// Read logical partition metadata from its predetermined location on a block
+// device. If readback fails, we also attempt to load from a backup copy.
+std::unique_ptr<LpMetadata> ReadMetadata(const char* block_device, uint32_t slot_number);
+
+// Read and validate the logical partition geometry from a block device.
+bool ReadLogicalPartitionGeometry(const char* block_device, LpMetadataGeometry* geometry);
+
+// Read logical partition metadata from an image file that was created with
+// WriteToImageFile().
+std::unique_ptr<LpMetadata> ReadFromImageFile(const char* file);
+
+} // namespace fs_mgr
+} // namespace android
+
+#endif /* LIBLP_READER_H_ */
diff --git a/fs_mgr/liblp/include/liblp/writer.h b/fs_mgr/liblp/include/liblp/writer.h
new file mode 100644
index 0000000..02fb21f
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/writer.h
@@ -0,0 +1,53 @@
+/*
+ * 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.
+ */
+
+#ifndef LIBLP_WRITER_H
+#define LIBLP_WRITER_H
+
+#include "metadata_format.h"
+
+namespace android {
+namespace fs_mgr {
+
+// When flashing the initial logical partition layout, we also write geometry
+// information at the start and end of the big physical partition. This helps
+// locate metadata and backup metadata in the case of corruption or a failed
+// update. For normal changes to the metadata, we never modify the geometry.
+enum class SyncMode {
+ // Write geometry information.
+ Flash,
+ // Normal update of a single slot.
+ Update
+};
+
+// Write the given partition table to the given block device, writing only
+// copies according to the given sync mode.
+//
+// This will perform some verification, such that the device has enough space
+// to store the metadata as well as all of its extents.
+//
+// The slot number indicates which metadata slot to use.
+bool WritePartitionTable(const char* block_device, const LpMetadata& metadata, SyncMode sync_mode,
+ uint32_t slot_number);
+
+// Helper function to serialize geometry and metadata to a normal file, for
+// flashing or debugging.
+bool WriteToImageFile(const char* file, const LpMetadata& metadata);
+
+} // namespace fs_mgr
+} // namespace android
+
+#endif /* LIBLP_WRITER_H */
diff --git a/fs_mgr/liblp/reader.cpp b/fs_mgr/liblp/reader.cpp
new file mode 100644
index 0000000..1b70da9
--- /dev/null
+++ b/fs_mgr/liblp/reader.cpp
@@ -0,0 +1,307 @@
+/*
+ * 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 "liblp/reader.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <functional>
+
+#include <android-base/file.h>
+#include <android-base/unique_fd.h>
+
+#include "utility.h"
+
+namespace android {
+namespace fs_mgr {
+
+// Parse an LpMetadataGeometry from a buffer. The buffer must be at least
+// LP_METADATA_GEOMETRY_SIZE bytes in size.
+static bool ParseGeometry(const void* buffer, LpMetadataGeometry* geometry) {
+ static_assert(sizeof(*geometry) <= LP_METADATA_GEOMETRY_SIZE);
+ memcpy(geometry, buffer, sizeof(*geometry));
+
+ // Check the magic signature.
+ if (geometry->magic != LP_METADATA_GEOMETRY_MAGIC) {
+ LERROR << "Logical partition metadata has invalid geometry magic signature.";
+ return false;
+ }
+ // Recompute and check the CRC32.
+ {
+ LpMetadataGeometry temp = *geometry;
+ memset(&temp.checksum, 0, sizeof(temp.checksum));
+ SHA256(&temp, sizeof(temp), temp.checksum);
+ if (memcmp(temp.checksum, geometry->checksum, sizeof(temp.checksum)) != 0) {
+ LERROR << "Logical partition metadata has invalid geometry checksum.";
+ return false;
+ }
+ }
+ // Check that the struct size is equal (this will have to change if we ever
+ // change the struct size in a release).
+ if (geometry->struct_size != sizeof(LpMetadataGeometry)) {
+ LERROR << "Logical partition metadata has invalid struct size.";
+ return false;
+ }
+ if (geometry->metadata_slot_count == 0) {
+ LERROR << "Logical partition metadata has invalid slot count.";
+ return false;
+ }
+
+ // Check that the metadata area and logical partition areas don't overlap.
+ off64_t end_of_metadata =
+ GetPrimaryMetadataOffset(*geometry, geometry->metadata_slot_count - 1) +
+ geometry->metadata_max_size;
+ if (uint64_t(end_of_metadata) > geometry->first_logical_sector * LP_SECTOR_SIZE) {
+ LERROR << "Logical partition metadata overlaps with logical partition contents.";
+ return false;
+ }
+ return true;
+}
+
+// Read and validate geometry information from a block device that holds
+// logical partitions. If the information is corrupted, this will attempt
+// to read it from a secondary backup location.
+static bool ReadLogicalPartitionGeometry(int fd, LpMetadataGeometry* geometry) {
+ // Read the first 4096 bytes.
+ std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(LP_METADATA_GEOMETRY_SIZE);
+ if (lseek64(fd, 0, SEEK_SET) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed";
+ return false;
+ }
+ if (!android::base::ReadFully(fd, buffer.get(), LP_METADATA_GEOMETRY_SIZE)) {
+ PERROR << __PRETTY_FUNCTION__ << "read " << LP_METADATA_GEOMETRY_SIZE << " bytes failed";
+ return false;
+ }
+ if (ParseGeometry(buffer.get(), geometry)) {
+ return true;
+ }
+
+ // Try the backup copy in the last 4096 bytes.
+ if (lseek64(fd, -LP_METADATA_GEOMETRY_SIZE, SEEK_END) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed, offset " << -LP_METADATA_GEOMETRY_SIZE;
+ return false;
+ }
+ if (!android::base::ReadFully(fd, buffer.get(), LP_METADATA_GEOMETRY_SIZE)) {
+ PERROR << __PRETTY_FUNCTION__ << "backup read " << LP_METADATA_GEOMETRY_SIZE
+ << " bytes failed";
+ return false;
+ }
+ return ParseGeometry(buffer.get(), geometry);
+}
+
+// Helper function to read geometry from a device without an open descriptor.
+bool ReadLogicalPartitionGeometry(const char* block_device, LpMetadataGeometry* geometry) {
+ android::base::unique_fd fd(open(block_device, O_RDONLY));
+ if (fd < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "open failed: " << block_device;
+ return false;
+ }
+ return ReadLogicalPartitionGeometry(fd, geometry);
+}
+
+static bool ValidateTableBounds(const LpMetadataHeader& header,
+ const LpMetadataTableDescriptor& table) {
+ if (table.offset > header.tables_size) {
+ return false;
+ }
+ uint64_t table_size = uint64_t(table.num_entries) * table.entry_size;
+ if (header.tables_size - table.offset < table_size) {
+ return false;
+ }
+ return true;
+}
+
+static bool ValidateMetadataHeader(const LpMetadataHeader& header) {
+ // To compute the header's checksum, we have to temporarily set its checksum
+ // field to 0.
+ {
+ LpMetadataHeader temp = header;
+ memset(&temp.header_checksum, 0, sizeof(temp.header_checksum));
+ SHA256(&temp, sizeof(temp), temp.header_checksum);
+ if (memcmp(temp.header_checksum, header.header_checksum, sizeof(temp.header_checksum)) != 0) {
+ LERROR << "Logical partition metadata has invalid checksum.";
+ return false;
+ }
+ }
+
+ // Do basic validation of key metadata bits.
+ if (header.magic != LP_METADATA_HEADER_MAGIC) {
+ LERROR << "Logical partition metadata has invalid magic value.";
+ return false;
+ }
+ // Check that the version is compatible.
+ if (header.major_version != LP_METADATA_MAJOR_VERSION ||
+ header.minor_version > LP_METADATA_MINOR_VERSION) {
+ LERROR << "Logical partition metadata has incompatible version.";
+ return false;
+ }
+ if (!ValidateTableBounds(header, header.partitions) ||
+ !ValidateTableBounds(header, header.extents)) {
+ LERROR << "Logical partition metadata has invalid table bounds.";
+ return false;
+ }
+ // Check that table entry sizes can accomodate their respective structs. If
+ // table sizes change, these checks will have to be adjusted.
+ if (header.partitions.entry_size != sizeof(LpMetadataPartition)) {
+ LERROR << "Logical partition metadata has invalid partition table entry size.";
+ return false;
+ }
+ if (header.extents.entry_size != sizeof(LpMetadataExtent)) {
+ LERROR << "Logical partition metadata has invalid extent table entry size.";
+ return false;
+ }
+ return true;
+}
+
+using ReadMetadataFn = std::function<bool(void* buffer, size_t num_bytes)>;
+
+// Parse and validate all metadata at the current position in the given file
+// descriptor.
+static std::unique_ptr<LpMetadata> ParseMetadata(int fd) {
+ // First read and validate the header.
+ std::unique_ptr<LpMetadata> metadata = std::make_unique<LpMetadata>();
+ if (!android::base::ReadFully(fd, &metadata->header, sizeof(metadata->header))) {
+ PERROR << __PRETTY_FUNCTION__ << "read " << sizeof(metadata->header) << "bytes failed";
+ return nullptr;
+ }
+ if (!ValidateMetadataHeader(metadata->header)) {
+ return nullptr;
+ }
+
+ LpMetadataHeader& header = metadata->header;
+
+ // Read the metadata payload. Allocation is fallible in case the metadata is
+ // corrupt and has some huge value.
+ std::unique_ptr<uint8_t[]> buffer(new (std::nothrow) uint8_t[header.tables_size]);
+ if (!buffer) {
+ LERROR << "Out of memory reading logical partition tables.";
+ return nullptr;
+ }
+ if (!android::base::ReadFully(fd, buffer.get(), header.tables_size)) {
+ PERROR << __PRETTY_FUNCTION__ << "read " << header.tables_size << "bytes failed";
+ return nullptr;
+ }
+
+ uint8_t checksum[32];
+ SHA256(buffer.get(), header.tables_size, checksum);
+ if (memcmp(checksum, header.tables_checksum, sizeof(checksum)) != 0) {
+ LERROR << "Logical partition metadata has invalid table checksum.";
+ return nullptr;
+ }
+
+ // ValidateTableSize ensured that |cursor| is valid for the number of
+ // entries in the table.
+ uint8_t* cursor = buffer.get() + header.partitions.offset;
+ for (size_t i = 0; i < header.partitions.num_entries; i++) {
+ LpMetadataPartition partition;
+ memcpy(&partition, cursor, sizeof(partition));
+ cursor += header.partitions.entry_size;
+
+ if (partition.attributes & ~LP_PARTITION_ATTRIBUTE_MASK) {
+ LERROR << "Logical partition has invalid attribute set.";
+ return nullptr;
+ }
+ if (partition.first_extent_index + partition.num_extents > header.extents.num_entries) {
+ LERROR << "Logical partition has invalid extent list.";
+ return nullptr;
+ }
+
+ metadata->partitions.push_back(partition);
+ }
+
+ cursor = buffer.get() + header.extents.offset;
+ for (size_t i = 0; i < header.extents.num_entries; i++) {
+ LpMetadataExtent extent;
+ memcpy(&extent, cursor, sizeof(extent));
+ cursor += header.extents.entry_size;
+
+ metadata->extents.push_back(extent);
+ }
+
+ return metadata;
+}
+
+std::unique_ptr<LpMetadata> ReadMetadata(const char* block_device, uint32_t slot_number) {
+ android::base::unique_fd fd(open(block_device, O_RDONLY));
+ if (fd < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "open failed: " << block_device;
+ return nullptr;
+ }
+ LpMetadataGeometry geometry;
+ if (!ReadLogicalPartitionGeometry(fd, &geometry)) {
+ return nullptr;
+ }
+
+ // First try the primary copy.
+ off64_t offset = GetPrimaryMetadataOffset(geometry, slot_number);
+ if (lseek64(fd, offset, SEEK_SET) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << offset;
+ return nullptr;
+ }
+ if (std::unique_ptr<LpMetadata> metadata = ParseMetadata(fd)) {
+ return metadata;
+ }
+
+ // Next try the backup copy.
+ offset = GetBackupMetadataOffset(geometry, slot_number);
+ if (lseek64(fd, offset, SEEK_END) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << offset;
+ return nullptr;
+ }
+ return ParseMetadata(fd);
+}
+
+std::unique_ptr<LpMetadata> ReadFromImageFile(const char* file) {
+ android::base::unique_fd fd(open(file, O_RDONLY));
+ if (fd < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "open failed: " << file;
+ return nullptr;
+ }
+
+ LpMetadataGeometry geometry;
+ if (!ReadLogicalPartitionGeometry(fd, &geometry)) {
+ return nullptr;
+ }
+ if (lseek64(fd, LP_METADATA_GEOMETRY_SIZE, SEEK_SET) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << LP_METADATA_GEOMETRY_SIZE;
+ return nullptr;
+ }
+ std::unique_ptr<LpMetadata> metadata = ParseMetadata(fd);
+ if (!metadata) {
+ return nullptr;
+ }
+ metadata->geometry = geometry;
+ return metadata;
+}
+
+static std::string NameFromFixedArray(const char* name, size_t buffer_size) {
+ // If the end of the buffer has a null character, it's safe to assume the
+ // buffer is null terminated. Otherwise, we cap the string to the input
+ // buffer size.
+ if (name[buffer_size - 1] == '\0') {
+ return std::string(name);
+ }
+ return std::string(name, buffer_size);
+}
+
+std::string GetPartitionName(const LpMetadataPartition& partition) {
+ return NameFromFixedArray(partition.name, sizeof(partition.name));
+}
+
+} // namespace fs_mgr
+} // namespace android
diff --git a/fs_mgr/liblp/utility.cpp b/fs_mgr/liblp/utility.cpp
new file mode 100644
index 0000000..c4b7028
--- /dev/null
+++ b/fs_mgr/liblp/utility.cpp
@@ -0,0 +1,89 @@
+/*
+ * 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 <fcntl.h>
+#include <linux/fs.h>
+#include <stdint.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <android-base/file.h>
+#include <openssl/sha.h>
+#include <uuid/uuid.h>
+
+#include "utility.h"
+
+namespace android {
+namespace fs_mgr {
+
+bool GetDescriptorSize(int fd, uint64_t* size) {
+ struct stat s;
+ if (fstat(fd, &s) < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "fstat failed";
+ return false;
+ }
+
+ if (S_ISBLK(s.st_mode)) {
+ if (ioctl(fd, BLKGETSIZE64, size) != -1) {
+ return true;
+ }
+ }
+
+ off64_t result = lseek64(fd, 0, SEEK_END);
+ if (result == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed";
+ return false;
+ }
+
+ *size = result;
+ return true;
+}
+
+off64_t GetPrimaryMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number) {
+ CHECK(slot_number < geometry.metadata_slot_count);
+
+ off64_t offset = LP_METADATA_GEOMETRY_SIZE + geometry.metadata_max_size * slot_number;
+ CHECK(offset + geometry.metadata_max_size <=
+ off64_t(geometry.first_logical_sector * LP_SECTOR_SIZE));
+ return offset;
+}
+
+off64_t GetBackupMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number) {
+ CHECK(slot_number < geometry.metadata_slot_count);
+ off64_t start = off64_t(-LP_METADATA_GEOMETRY_SIZE) -
+ off64_t(geometry.metadata_max_size) * geometry.metadata_slot_count;
+ return start + off64_t(geometry.metadata_max_size * slot_number);
+}
+
+void SHA256(const void* data, size_t length, uint8_t out[32]) {
+ SHA256_CTX c;
+ SHA256_Init(&c);
+ SHA256_Update(&c, data, length);
+ SHA256_Final(out, &c);
+}
+
+std::string GetPartitionGuid(const LpMetadataPartition& partition) {
+ // 32 hex characters, four hyphens. Unfortunately libext2_uuid provides no
+ // macro to assist with buffer sizing.
+ static const size_t kGuidLen = 36;
+ char buffer[kGuidLen + 1];
+ uuid_unparse(partition.guid, buffer);
+ return buffer;
+}
+
+} // namespace fs_mgr
+} // namespace android
diff --git a/fs_mgr/liblp/utility.h b/fs_mgr/liblp/utility.h
new file mode 100644
index 0000000..dc559ed
--- /dev/null
+++ b/fs_mgr/liblp/utility.h
@@ -0,0 +1,53 @@
+/*
+ * 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.
+ */
+
+#ifndef LIBLP_UTILITY_H
+#define LIBLP_UTILITY_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <android-base/logging.h>
+
+#include "liblp/metadata_format.h"
+
+#define LP_TAG "[liblp]"
+#define LERROR LOG(ERROR) << LP_TAG
+#define PERROR PLOG(ERROR) << LP_TAG
+
+namespace android {
+namespace fs_mgr {
+
+// Determine the size of a block device (or file). Logs and returns false on
+// error. After calling this, the position of |fd| may have changed.
+bool GetDescriptorSize(int fd, uint64_t* size);
+
+// Return the offset of a primary metadata slot, relative to the start of the
+// device.
+off64_t GetPrimaryMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number);
+
+// Return the offset of a backup metadata slot, relative to the end of the
+// device.
+off64_t GetBackupMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number);
+
+// Compute a SHA256 hash.
+void SHA256(const void* data, size_t length, uint8_t out[32]);
+
+} // namespace fs_mgr
+} // namespace android
+
+#endif // LIBLP_UTILITY_H
diff --git a/fs_mgr/liblp/writer.cpp b/fs_mgr/liblp/writer.cpp
new file mode 100644
index 0000000..aab244a
--- /dev/null
+++ b/fs_mgr/liblp/writer.cpp
@@ -0,0 +1,244 @@
+/*
+ * 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 <inttypes.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/unique_fd.h>
+
+#include "liblp/reader.h"
+#include "liblp/writer.h"
+#include "utility.h"
+
+namespace android {
+namespace fs_mgr {
+
+static std::string SerializeGeometry(const LpMetadataGeometry& input) {
+ LpMetadataGeometry geometry = input;
+ memset(geometry.checksum, 0, sizeof(geometry.checksum));
+ SHA256(&geometry, sizeof(geometry), geometry.checksum);
+ return std::string(reinterpret_cast<const char*>(&geometry), sizeof(geometry));
+}
+
+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.first_logical_sector == g2.first_logical_sector &&
+ g1.last_logical_sector == g2.last_logical_sector;
+}
+
+static 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));
+
+ // Compute positions of tables.
+ header.partitions.offset = 0;
+ header.extents.offset = header.partitions.offset + partitions.size();
+ header.tables_size = header.extents.offset + extents.size();
+
+ // Compute payload checksum.
+ std::string tables = partitions + extents;
+ SHA256(tables.data(), tables.size(), header.tables_checksum);
+
+ // Compute header checksum.
+ memset(header.header_checksum, 0, sizeof(header.header_checksum));
+ SHA256(&header, sizeof(header), header.header_checksum);
+
+ std::string header_blob =
+ std::string(reinterpret_cast<const char*>(&metadata.header), sizeof(metadata.header));
+ return header_blob + tables;
+}
+
+// Perform sanity checks so we don't accidentally overwrite valid metadata
+// with potentially invalid metadata, or random partition data with metadata.
+static bool ValidateGeometryAndMetadata(const LpMetadata& metadata, uint64_t blockdevice_size,
+ uint64_t metadata_size) {
+ const LpMetadataHeader& header = metadata.header;
+ const LpMetadataGeometry& geometry = metadata.geometry;
+ // Validate the usable sector range.
+ if (geometry.first_logical_sector > geometry.last_logical_sector) {
+ LERROR << "Logical partition metadata has invalid sector range.";
+ return false;
+ }
+ // Make sure we're writing within the space reserved.
+ if (metadata_size > geometry.metadata_max_size) {
+ LERROR << "Logical partition metadata is too large.";
+ 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;
+ if (reserved_size > blockdevice_size ||
+ reserved_size > geometry.first_logical_sector * LP_SECTOR_SIZE) {
+ LERROR << "Not enough space to store all logical partition metadata slots.";
+ return false;
+ }
+ if (blockdevice_size - reserved_size < (geometry.last_logical_sector + 1) * LP_SECTOR_SIZE) {
+ LERROR << "Not enough space to backup all logical partition metadata slots.";
+ return false;
+ }
+
+ // 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.
+ for (const auto& extent : metadata.extents) {
+ if (extent.target_type == LP_TARGET_TYPE_LINEAR) {
+ uint64_t physical_sector = extent.target_data;
+ if (physical_sector < geometry.first_logical_sector ||
+ physical_sector + extent.num_sectors > geometry.last_logical_sector) {
+ LERROR << "Extent table entry is out of bounds.";
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
+bool WritePartitionTable(const char* block_device, const LpMetadata& metadata, SyncMode sync_mode,
+ uint32_t slot_number) {
+ android::base::unique_fd fd(open(block_device, O_RDWR | O_SYNC));
+ if (fd < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "open failed: " << block_device;
+ return false;
+ }
+
+ uint64_t size;
+ if (!GetDescriptorSize(fd, &size)) {
+ return false;
+ }
+
+ const LpMetadataGeometry& geometry = metadata.geometry;
+ if (sync_mode != SyncMode::Flash) {
+ // Verify that the old geometry is identical. If it's not, then we've
+ // based this new metadata on invalid assumptions.
+ LpMetadataGeometry old_geometry;
+ if (!ReadLogicalPartitionGeometry(block_device, &old_geometry)) {
+ return false;
+ }
+ if (!CompareGeometry(geometry, old_geometry)) {
+ LERROR << "Incompatible geometry in new logical partition metadata";
+ return false;
+ }
+ }
+
+ // Make sure we're writing to a valid metadata slot.
+ if (slot_number >= geometry.metadata_slot_count) {
+ LERROR << "Invalid logical partition metadata slot number.";
+ return false;
+ }
+
+ // 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 = SerializeMetadata(metadata);
+ if (!ValidateGeometryAndMetadata(metadata, size, blob.size())) {
+ return false;
+ }
+
+ // First write geometry if this is a flash operation. It gets written to
+ // the first and last 4096-byte regions of the device.
+ if (sync_mode == SyncMode::Flash) {
+ std::string blob = SerializeGeometry(metadata.geometry);
+ if (lseek64(fd, 0, SEEK_SET) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset 0";
+ return false;
+ }
+ if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
+ PERROR << __PRETTY_FUNCTION__ << "write " << blob.size()
+ << " bytes failed: " << block_device;
+ return false;
+ }
+ if (lseek64(fd, -LP_METADATA_GEOMETRY_SIZE, SEEK_END) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << -LP_METADATA_GEOMETRY_SIZE;
+ return false;
+ }
+ if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
+ PERROR << __PRETTY_FUNCTION__ << "backup write " << blob.size()
+ << " bytes failed: " << block_device;
+ return false;
+ }
+ }
+
+ // Write the primary copy of the metadata.
+ off64_t primary_offset = GetPrimaryMetadataOffset(geometry, slot_number);
+ if (lseek64(fd, primary_offset, SEEK_SET) == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << primary_offset;
+ return false;
+ }
+ if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
+ PERROR << __PRETTY_FUNCTION__ << "write " << blob.size()
+ << " bytes failed: " << block_device;
+ return false;
+ }
+
+ // Write the backup copy of the metadata.
+ off64_t backup_offset = GetBackupMetadataOffset(geometry, slot_number);
+ off64_t abs_offset = lseek64(fd, backup_offset, SEEK_END);
+ if (abs_offset == (off64_t)-1) {
+ PERROR << __PRETTY_FUNCTION__ << "lseek64 failed: offset " << backup_offset;
+ return false;
+ }
+ if (abs_offset < off64_t((geometry.last_logical_sector + 1) * LP_SECTOR_SIZE)) {
+ PERROR << __PRETTY_FUNCTION__ << "backup offset " << abs_offset
+ << " is within logical partition bounds, sector " << geometry.last_logical_sector;
+ return false;
+ }
+ if (!android::base::WriteFully(fd, blob.data(), blob.size())) {
+ PERROR << __PRETTY_FUNCTION__ << "backup write " << blob.size()
+ << " bytes failed: " << block_device;
+ return false;
+ }
+ return true;
+}
+
+bool WriteToImageFile(const char* file, const LpMetadata& input) {
+ std::string geometry = SerializeGeometry(input.geometry);
+ std::string padding(LP_METADATA_GEOMETRY_SIZE - geometry.size(), '\0');
+ std::string metadata = SerializeMetadata(input);
+
+ std::string everything = geometry + padding + metadata;
+
+ android::base::unique_fd fd(open(file, O_CREAT | O_RDWR | O_TRUNC, 0644));
+ if (fd < 0) {
+ PERROR << __PRETTY_FUNCTION__ << "open failed: " << file;
+ return false;
+ }
+ if (!android::base::WriteFully(fd, everything.data(), everything.size())) {
+ PERROR << __PRETTY_FUNCTION__ << "write " << everything.size() << " bytes failed: " << file;
+ return false;
+ }
+ return true;
+}
+
+} // namespace fs_mgr
+} // namespace android