/*

* Copyright (C) 2016 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 "MetadataCrypt.h"

#include "KeyBuffer.h"

#include <fstream>

#include <string>

#include <fcntl.h>

#include <sys/param.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <android-base/logging.h>

#include <android-base/properties.h>

#include <android-base/strings.h>

#include <android-base/unique_fd.h>

#include <cutils/fs.h>

#include <fs_mgr.h>

#include <libdm/dm.h>

#include <libgsi/libgsi.h>

#include "Checkpoint.h"

#include "CryptoType.h"

#include "EncryptInplace.h"

#include "FsCrypt.h"

#include "KeyStorage.h"

#include "KeyUtil.h"

#include "Keystore.h"

#include "Utils.h"

#include "VoldUtil.h"

#include "fs/Ext4.h"

#include "fs/F2fs.h"

namespace android {

namespace vold {

using android::base::Basename;

using android::fs_mgr::FstabEntry;

using android::fs_mgr::GetEntryForMountPoint;

using android::fscrypt::GetFirstApiLevel;

using android::fscrypt::KeyType;

using android::vold::KeyBuffer;

using namespace android::dm;

using namespace std::chrono_literals;

// Parsed from metadata options

struct CryptoOptions {

struct CryptoType cipher = invalid_crypto_type;

bool use_legacy_options_format = false;

bool set_dun = true; // Non-legacy driver always sets DUN

KeyType key_type = KeyType::kRaw;

};

static const std::string kDmNameUserdata = "userdata";

// The first entry in this table is the default crypto type.

constexpr CryptoType supported_crypto_types[] = {aes_256_xts, adiantum};

static_assert(validateSupportedCryptoTypes(64, supported_crypto_types,

array_length(supported_crypto_types)),

"We have a CryptoType which was incompletely constructed.");

constexpr CryptoType legacy_aes_256_xts =

CryptoType().set_config_name("aes-256-xts").set_kernel_name("AES-256-XTS").set_keysize(64);

static_assert(isValidCryptoType(64, legacy_aes_256_xts),

"We have a CryptoType which was incompletely constructed.");

// Returns KeyGeneration suitable for key as described in CryptoOptions

const KeyGeneration makeGen(const CryptoOptions& options) {

return KeyGeneration{options.cipher.get_keysize(), true, options.key_type};

}

void defaultkey_precreate_dm_device() {

auto& dm = DeviceMapper::Instance();

if (dm.GetState(kDmNameUserdata) != DmDeviceState::INVALID) {

LOG(INFO) << "Not pre-creating userdata encryption device; device already exists";

return;

}

if (!dm.CreatePlaceholderDevice(kDmNameUserdata)) {

LOG(ERROR) << "Failed to pre-create userdata metadata encryption device";

}

}

static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device, bool needs_encrypt) {

// fs_mgr_do_mount runs fsck. Use setexeccon to run trusted

// partitions in the fsck domain.

if (setexeccon(android::vold::sFsckContext)) {

PLOG(ERROR) << "Failed to setexeccon";

return false;

}

auto mount_rc = fs_mgr_do_mount(&fstab_default, mount_point, blk_device,

android::vold::cp_needsCheckpoint(), needs_encrypt);

if (setexeccon(nullptr)) {

PLOG(ERROR) << "Failed to clear setexeccon";

return false;

}

if (mount_rc != 0) {

LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;

return false;

}

LOG(DEBUG) << "Mounted " << mount_point;

return true;

}

static bool read_key(const std::string& metadata_key_dir, const KeyGeneration& gen, bool first_key,

KeyBuffer* key) {

if (metadata_key_dir.empty()) {

LOG(ERROR) << "Failed to get metadata_key_dir";

return false;

}

std::string sKey;

auto dir = metadata_key_dir + "/key";

LOG(DEBUG) << "metadata_key_dir/key: " << dir;

if (!MkdirsSync(dir, 0700)) return false;

auto in_dsu = android::base::GetBoolProperty("ro.gsid.image_running", false);

// !pathExists(dir) does not imply there's a factory reset when in DSU mode.

if (!pathExists(dir) && !in_dsu && first_key) {

auto delete_all = android::base::GetBoolProperty(

"ro.crypto.metadata_init_delete_all_keys.enabled", false);

if (delete_all) {

LOG(INFO) << "Metadata key does not exist, calling deleteAllKeys";

Keystore::deleteAllKeys();

} else {

LOG(DEBUG) << "Metadata key does not exist but "

"ro.crypto.metadata_init_delete_all_keys.enabled is false";

}

}

auto temp = metadata_key_dir + "/tmp";

return retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key);

}

static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {

if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {

PLOG(ERROR) << "Unable to measure size of " << real_blkdev;

return false;

}

return true;

}

static bool create_crypto_blk_dev(const std::string& dm_name, const std::string& blk_device,

const KeyBuffer& key, const CryptoOptions& options,

std::string* crypto_blkdev, uint64_t* nr_sec, bool is_userdata) {

if (!get_number_of_sectors(blk_device, nr_sec)) return false;

// TODO(paulcrowley): don't hardcode that DmTargetDefaultKey uses 4096-byte

// sectors

*nr_sec &= ~7;

KeyBuffer module_key;

if (!prepareKeyForUse(key, options.key_type, &module_key)) return false;

KeyBuffer hex_key_buffer;

if (android::vold::StrToHex(module_key, hex_key_buffer) != android::OK) {

LOG(ERROR) << "Failed to turn key to hex";

return false;

}

std::string hex_key(hex_key_buffer.data(), hex_key_buffer.size());

auto target = std::make_unique<DmTargetDefaultKey>(0, *nr_sec, options.cipher.get_kernel_name(),

hex_key, blk_device, 0);

if (options.use_legacy_options_format) target->SetUseLegacyOptionsFormat();

if (options.set_dun) target->SetSetDun();

switch (options.key_type) {

case KeyType::kRaw:

break;

case KeyType::kHwWrappedV0:

case KeyType::kHwWrapped:

// The dm-default-key option "wrappedkey_v0" actually works for both wrapped key

// versions. Eventually a "wrappedkey" alias should be added and used, but for now just

// continue using "wrappedkey_v0".

target->SetWrappedKeyV0();

break;

}

DmTable table;

table.AddTarget(std::move(target));

auto& dm = DeviceMapper::Instance();

if (dm_name == kDmNameUserdata && dm.GetState(dm_name) == DmDeviceState::SUSPENDED) {

// The device was created in advance, populate it now.

if (!dm.LoadTableAndActivate(dm_name, table)) {

LOG(ERROR) << "Failed to populate default-key device " << dm_name;

return false;

}

if (!dm.WaitForDevice(dm_name, 20s, crypto_blkdev)) {

LOG(ERROR) << "Failed to wait for default-key device " << dm_name;

return false;

}

} else if (!dm.CreateDevice(dm_name, table, crypto_blkdev, 5s)) {

LOG(ERROR) << "Could not create default-key device " << dm_name;

return false;

}

// If there are multiple partitions used for a single mount, F2FS stores

// their partition paths in superblock. If the paths are dm targets, we

// cannot guarantee them across device boots. Let's use the logical paths.

if (is_userdata) {

*crypto_blkdev = "/dev/block/mapper/" + dm_name;

}

return true;

}

static const CryptoType& lookup_cipher(const std::string& cipher_name) {

if (cipher_name.empty()) return supported_crypto_types[0];

for (size_t i = 0; i < array_length(supported_crypto_types); i++) {

if (cipher_name == supported_crypto_types[i].get_config_name()) {

return supported_crypto_types[i];

}

}

return invalid_crypto_type;

}

static bool parse_options(const std::string& options_string, CryptoOptions* options) {

auto parts = android::base::Split(options_string, ":");

if (parts.size() < 1 || parts.size() > 2) {

LOG(ERROR) << "Invalid metadata encryption option: " << options_string;

return false;

}

std::string cipher_name = parts[0];

options->cipher = lookup_cipher(cipher_name);

if (options->cipher.get_kernel_name() == nullptr) {

LOG(ERROR) << "No metadata cipher named " << cipher_name << " found";

return false;

}

if (parts.size() == 2) {

if (parts[1] == "wrappedkey_v0") {

options->key_type = KeyType::kHwWrappedV0;

} else if (parts[1] == "wrappedkey") {

options->key_type = KeyType::kHwWrapped;

} else {

LOG(ERROR) << "Invalid metadata encryption flag: " << parts[1];

return false;

}

}

return true;

}

class EncryptionInProgress {

private:

std::string file_path_;

bool need_cleanup_ = false;

public:

EncryptionInProgress(const FstabEntry& entry) {

file_path_ = fs_mgr_metadata_encryption_in_progress_file_name(entry);

}

[[nodiscard]] bool Mark() {

{

std::ofstream touch(file_path_);

if (!touch.is_open()) {

PLOG(ERROR) << "Failed to mark metadata encryption in progress " << file_path_;

return false;

}

need_cleanup_ = true;

}

if (!android::vold::FsyncParentDirectory(file_path_)) return false;

LOG(INFO) << "Marked metadata encryption in progress (" << file_path_ << ")";

return true;

}

[[nodiscard]] bool Remove() {

need_cleanup_ = false;

if (unlink(file_path_.c_str()) != 0) {

PLOG(ERROR) << "Failed to clear metadata encryption in progress (" << file_path_ << ")";

return false;

}

if (!android::vold::FsyncParentDirectory(file_path_)) return false;

LOG(INFO) << "Cleared metadata encryption in progress (" << file_path_ << ")";

return true;

}

~EncryptionInProgress() {

if (need_cleanup_) (void)Remove();

}

};

bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,

bool needs_encrypt, bool should_format,

const std::string& fs_type, bool is_zoned,

const std::vector<std::string>& user_devices,

const std::vector<bool>& device_aliased, int64_t length) {

LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point

<< " encrypt: " << needs_encrypt << " format: " << should_format << " with "

<< fs_type << " block device: " << blk_device << " with zoned " << is_zoned

<< " length: " << length;

for (auto& device : user_devices) {

LOG(DEBUG) << " - user devices: " << device;

}

auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");

if (encrypted_state != "" && encrypted_state != "encrypted") {

LOG(ERROR) << "fscrypt_mount_metadata_encrypted got unexpected starting state: "

<< encrypted_state;

return false;

}

auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);

if (!data_rec) {

LOG(ERROR) << "Failed to get data_rec for " << mount_point;

return false;

}

unsigned int options_format_version = android::base::GetUintProperty<unsigned int>(

"ro.crypto.dm_default_key.options_format.version",

(GetFirstApiLevel() <= __ANDROID_API_Q__ ? 1 : 2));

CryptoOptions options;

if (options_format_version == 1) {

if (!data_rec->metadata_encryption_options.empty()) {

LOG(ERROR) << "metadata_encryption options cannot be set in legacy mode";

return false;

}

options.cipher = legacy_aes_256_xts;

options.use_legacy_options_format = true;

if (is_metadata_wrapped_key_supported())

options.key_type = KeyType::kHwWrappedV0;

options.set_dun = android::base::GetBoolProperty("ro.crypto.set_dun", false);

if (!options.set_dun && data_rec->fs_mgr_flags.checkpoint_blk) {

LOG(ERROR)

<< "Block checkpoints and metadata encryption require ro.crypto.set_dun option";

return false;

}

} else if (options_format_version == 2) {

if (!parse_options(data_rec->metadata_encryption_options, &options)) return false;

} else {

LOG(ERROR) << "Unknown options_format_version: " << options_format_version;

return false;

}

auto default_metadata_key_dir = data_rec->metadata_key_dir;

auto use_subdirs = false;

if (!user_devices.empty() &&

(should_format || pathExists(default_metadata_key_dir + "/default"))) {

default_metadata_key_dir = default_metadata_key_dir + "/default";

use_subdirs = true;

}

auto gen = needs_encrypt ? makeGen(options) : neverGen();

KeyBuffer key;

if (!read_key(default_metadata_key_dir, gen, true, &key)) {

LOG(ERROR) << "read_key failed in mountFstab";

return false;

}

std::string crypto_blkdev;

uint64_t nr_sec;

if (!create_crypto_blk_dev(kDmNameUserdata, blk_device, key, options, &crypto_blkdev, &nr_sec,

true)) {

LOG(ERROR) << "create_crypto_blk_dev failed in mountFstab";

return false;

}

// create dm-default-key for user devices

std::vector<std::string> crypto_user_blkdev;

for (auto& device : user_devices) {

std::string name = Basename(device);

auto metadata_key_dir = data_rec->metadata_key_dir + "/" + name;

if (!use_subdirs) {

break;

}

if (!read_key(metadata_key_dir, gen, false, &key)) {

LOG(ERROR) << "read_key failed with zoned device: " << device;

return false;

}

std::string crypto_blkdev_arg;

if (!create_crypto_blk_dev(name, device, key, options, &crypto_blkdev_arg, &nr_sec, true)) {

LOG(ERROR) << "fscrypt_mount_metadata_encrypted: failed with device: " << device;

return false;

}

crypto_user_blkdev.push_back(crypto_blkdev_arg.c_str());

}

if (needs_encrypt) {

EncryptionInProgress marker(*data_rec);

if (!marker.Mark()) return false;

if (should_format) {

status_t error;

if (fs_type == "ext4") {

error = ext4::Format(crypto_blkdev, 0, mount_point);

} else if (fs_type == "f2fs") {

error = f2fs::Format(crypto_blkdev, is_zoned, crypto_user_blkdev, device_aliased,

length);

} else {

LOG(ERROR) << "Unknown filesystem type: " << fs_type;

return false;

}

if (error != 0) {

LOG(ERROR) << "Format of " << crypto_blkdev << " for " << mount_point

<< " failed (err=" << error << ").";

return false;

}

LOG(DEBUG) << "Format of " << crypto_blkdev << " for " << mount_point << " succeeded.";

} else {

if (!user_devices.empty() && fs_mgr_is_f2fs(blk_device)) {

LOG(ERROR) << "encrypt_inplace cannot support zoned or userdata_exp device; should "

"format it.";

return false;

}

if (!encrypt_inplace(crypto_blkdev, blk_device, nr_sec)) {

LOG(ERROR) << "encrypt_inplace failed in mountFstab";

return false;

}

}

if (!marker.Remove()) return false;

}

LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;

mount_via_fs_mgr(mount_point.c_str(), crypto_blkdev.c_str(), needs_encrypt);

// Record that there's at least one fstab entry with metadata encryption

if (!android::base::SetProperty("ro.crypto.metadata.enabled", "true")) {

LOG(WARNING) << "failed to set ro.crypto.metadata.enabled"; // This isn't fatal

}

return true;

}

static bool get_volume_options(CryptoOptions* options) {

return parse_options(android::base::GetProperty("ro.crypto.volume.metadata.encryption", ""),

options);

}

bool defaultkey_volume_keygen(KeyGeneration* gen) {

CryptoOptions options;

if (!get_volume_options(&options)) return false;

*gen = makeGen(options);

return true;

}

bool defaultkey_setup_ext_volume(const std::string& label, const std::string& blk_device,

const KeyBuffer& key, std::string* out_crypto_blkdev) {

LOG(DEBUG) << "defaultkey_setup_ext_volume: " << label << " " << blk_device;

CryptoOptions options;

if (!get_volume_options(&options)) return false;

uint64_t nr_sec;

return create_crypto_blk_dev(label, blk_device, key, options, out_crypto_blkdev, &nr_sec,

false);

}

bool destroy_dsu_metadata_key(const std::string& dsu_slot) {

LOG(DEBUG) << "destroy_dsu_metadata_key: " << dsu_slot;

const auto dsu_metadata_key_dir = android::gsi::GetDsuMetadataKeyDir(dsu_slot);

if (!pathExists(dsu_metadata_key_dir)) {

LOG(DEBUG) << "DSU metadata_key_dir doesn't exist, nothing to remove: "

<< dsu_metadata_key_dir;

return true;

}

// Ensure that the DSU key directory is different from the host OS'.

// Under normal circumstances, this should never happen, but handle it just in case.

if (auto data_rec = GetEntryForMountPoint(&fstab_default, "/data")) {

if (dsu_metadata_key_dir == data_rec->metadata_key_dir) {

LOG(ERROR) << "DSU metadata_key_dir is same as host OS: " << dsu_metadata_key_dir;

return false;

}

}

bool ok = true;

for (auto suffix : {"/key", "/tmp"}) {

const auto key_path = dsu_metadata_key_dir + suffix;

if (pathExists(key_path)) {

LOG(DEBUG) << "Destroy key: " << key_path;

if (!android::vold::destroyKey(key_path)) {

LOG(ERROR) << "Failed to destroyKey(): " << key_path;

ok = false;

}

}

}

if (!ok) {

return false;

}

LOG(DEBUG) << "Remove DSU metadata_key_dir: " << dsu_metadata_key_dir;

// DeleteDirContentsAndDir() already logged any error, so don't log repeatedly.

return android::vold::DeleteDirContentsAndDir(dsu_metadata_key_dir) == android::OK;

}

} // namespace vold

} // namespace android