crypto/fscrypt/MetadataCrypt.cpp - android_bootable_recovery - Gitiles

 /*
  * 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 <algorithm>
 #include <string>
 #include <thread>
 #include <vector>

 #include <fcntl.h>
 #include <sys/param.h>
 #include <sys/stat.h>
 #include <sys/types.h>

 #include <android-base/file.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 "Checkpoint.h"
 #include "CryptoType.h"
 #include "EncryptInplace.h"
 #include "FsCrypt.h"
 #include "KeyStorage.h"
 #include "KeyUtil.h"
 #include "Keymaster.h"
 #include "Utils.h"
 #include "VoldUtil.h"

 #define TABLE_LOAD_RETRIES 10


 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::GetEntryForMountPoint;
 using ::KeyBuffer;
 using namespace android::dm;

 // 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
     bool use_hw_wrapped_key = false;
 };

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

 static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
 static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";

 // 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.use_hw_wrapped_key};
 }

 static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
     // We're about to mount data not verified by verified boot.  Tell Keymaster instances that early
     // boot has ended.
     ::Keymaster::earlyBootEnded();

     // fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
     // partitions in the fsck domain.
     if (setexeccon(::sFsckContext)) {
         PLOG(ERROR) << "Failed to setexeccon";
         return false;
     }

     if (fstab_default.empty()) {
         if (!ReadDefaultFstab(&fstab_default)) {
             PLOG(ERROR) << "Failed to open default fstab";
             return -1;
         }
     }
     auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
                                     const_cast<char*>(blk_device), nullptr,
                                     ::cp_needsCheckpoint(), true);
     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(INFO) << "mount_via_fs_mgr::Mounted " << mount_point;
     return true;
 }

 // Note: It is possible to orphan a key if it is removed before deleting
 // Update this once keymaster APIs change, and we have a proper commit.
 static void commit_key(const std::string& dir) {
     while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
         LOG(ERROR) << "Wait for boot timed out";
     }
     Keymaster keymaster;
     auto keyPath = dir + "/" + kFn_keymaster_key_blob;
     auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
     std::string key;

     if (!android::base::ReadFileToString(keyPath, &key)) {
         LOG(ERROR) << "Failed to read old key: " << dir;
         return;
     }
     if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
         PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
         return;
     }
     if (!keymaster.deleteKey(key)) {
         LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
     }
     LOG(INFO) << "Old Key deleted: " << dir;
 }

 static bool read_key(const std::string& metadata_key_dir, const KeyGeneration& gen,
                      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(INFO) << "metadata_key_dir/key: " << dir;
     if (fs_mkdirs(dir.c_str(), 0700)) {
         PLOG(ERROR) << "Creating directories: " << dir;
         return false;
     }
     auto temp = metadata_key_dir + "/tmp";
     auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
     /* If we have a leftover upgraded key, delete it.
      * We either failed an update and must return to the old key,
      * or we rebooted before commiting the keys in a freak accident.
      * Either way, we can re-upgrade the key if we need to.
      */

     Keymaster keymaster;
     if (pathExists(newKeyPath)) {
         if (!android::base::ReadFileToString(newKeyPath, &sKey))
             LOG(ERROR) << "Failed to read incomplete key: " << dir;
         else if (!keymaster.deleteKey(sKey))
             LOG(ERROR) << "Incomplete key deletion failed, continuing anyway: " << dir;
         else
             unlink(newKeyPath.c_str());
     }
     bool needs_cp = cp_needsCheckpoint();
     if (!retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key, true)) return false;
     if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
     return true;
 }

 static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
     if (::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) {
     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 (options.use_hw_wrapped_key) {
         if (!exportWrappedStorageKey(key, &module_key)) {
             LOG(ERROR) << "Failed to get ephemeral wrapped key";
             return false;
         }
     } else {
         module_key = key;
     }

     KeyBuffer hex_key_buffer;
     if (::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();
     if (options.use_hw_wrapped_key) target->SetWrappedKeyV0();

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

     auto& dm = DeviceMapper::Instance();
     for (int i = 0;; i++) {
         if (dm.CreateDevice(dm_name, table)) {
             break;
         }
         if (i + 1 >= TABLE_LOAD_RETRIES) {
             PLOG(ERROR) << "Could not create default-key device " << dm_name;
             return false;
         }
         PLOG(INFO) << "Could not create default-key device, retrying";
         usleep(500000);
     }

     if (!dm.GetDmDevicePathByName(dm_name, crypto_blkdev)) {
         LOG(ERROR) << "Cannot retrieve default-key device status " << dm_name;
         return false;
     }
     std::stringstream ss;
     ss << *crypto_blkdev;
     LOG(INFO) << "Created device: " << ss.str();
     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->use_hw_wrapped_key = true;
         } else {
             LOG(ERROR) << "Invalid metadata encryption flag: " << parts[1];
             return false;
         }
     }
     return true;
 }

 bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,
                                       bool needs_encrypt) {
     LOG(INFO) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
     auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
     if (encrypted_state != "" && encrypted_state != "encrypted") {
         LOG(ERROR) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
         return false;
     }
     if (fstab_default.empty()) {
         if (!ReadDefaultFstab(&fstab_default)) {
             PLOG(ERROR) << "Failed to open default fstab";
             return -1;
         }
     }
     auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
     if (!data_rec) {
         LOG(ERROR) << "Failed to get data_rec for " << mount_point;
         return false;
     }

     constexpr unsigned int pre_gki_level = 29;
     unsigned int options_format_version = android::base::GetUintProperty<unsigned int>(
             "ro.crypto.dm_default_key.options_format.version",
             (GetFirstApiLevel() <= pre_gki_level ? 1 : 2));

     CryptoOptions options;
     if (options_format_version == 1) {
         if (!data_rec->metadata_encryption.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.use_hw_wrapped_key = true;
             LOG(INFO) << "metadata_wrapped_key_true";
         }
         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)) return false;
     } else {
         LOG(ERROR) << "Unknown options_format_version: " << options_format_version;
         return false;
     }
     auto gen = needs_encrypt ? makeGen(options) : neverGen();
     KeyBuffer key;
     if (!read_key(data_rec->metadata_key_dir, gen, &key)) return false;

     std::string crypto_blkdev;
     uint64_t nr_sec;
     if (!create_crypto_blk_dev(kDmNameUserdata, blk_device, key, options, &crypto_blkdev, &nr_sec))
         return false;

     // FIXME handle the corrupt case
     if (needs_encrypt) {
         LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
         off64_t size_already_done = 0;
         auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), blk_device.data(), nr_sec,
                                          &size_already_done, nr_sec, 0, false);
         if (rc != 0) {
             LOG(ERROR) << "Inplace crypto failed with code: " << rc;
             return false;
         }
         if (static_cast<uint64_t>(size_already_done) != nr_sec) {
             LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
             return false;
         }
         LOG(INFO) << "Inplace encryption complete";
     }

     LOG(INFO) << "Mounting metadata-encrypted filesystem:" << mount_point;
     mount_via_fs_mgr(mount_point.c_str(), crypto_blkdev.c_str());
     android::base::SetProperty("ro.crypto.fs_crypto_blkdev", crypto_blkdev);

     // 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(ERROR) << "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);
 }
	/*
	* 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 <algorithm>
	#include <string>
	#include <thread>
	#include <vector>

	#include <fcntl.h>
	#include <sys/param.h>
	#include <sys/stat.h>
	#include <sys/types.h>

	#include <android-base/file.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 "Checkpoint.h"
	#include "CryptoType.h"
	#include "EncryptInplace.h"
	#include "FsCrypt.h"
	#include "KeyStorage.h"
	#include "KeyUtil.h"
	#include "Keymaster.h"
	#include "Utils.h"
	#include "VoldUtil.h"

	#define TABLE_LOAD_RETRIES 10


	using android::fs_mgr::FstabEntry;
	using android::fs_mgr::GetEntryForMountPoint;
	using ::KeyBuffer;
	using namespace android::dm;

	// 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
	bool use_hw_wrapped_key = false;
	};

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

	static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
	static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";

	// 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.use_hw_wrapped_key};
	}

	static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
	// We're about to mount data not verified by verified boot. Tell Keymaster instances that early
	// boot has ended.
	::Keymaster::earlyBootEnded();

	// fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
	// partitions in the fsck domain.
	if (setexeccon(::sFsckContext)) {
	PLOG(ERROR) << "Failed to setexeccon";
	return false;
	}

	if (fstab_default.empty()) {
	if (!ReadDefaultFstab(&fstab_default)) {
	PLOG(ERROR) << "Failed to open default fstab";
	return -1;
	}
	}
	auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
	const_cast<char*>(blk_device), nullptr,
	::cp_needsCheckpoint(), true);
	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(INFO) << "mount_via_fs_mgr::Mounted " << mount_point;
	return true;
	}

	// Note: It is possible to orphan a key if it is removed before deleting
	// Update this once keymaster APIs change, and we have a proper commit.
	static void commit_key(const std::string& dir) {
	while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
	LOG(ERROR) << "Wait for boot timed out";
	}
	Keymaster keymaster;
	auto keyPath = dir + "/" + kFn_keymaster_key_blob;
	auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
	std::string key;

	if (!android::base::ReadFileToString(keyPath, &key)) {
	LOG(ERROR) << "Failed to read old key: " << dir;
	return;
	}
	if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
	PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
	return;
	}
	if (!keymaster.deleteKey(key)) {
	LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
	}
	LOG(INFO) << "Old Key deleted: " << dir;
	}

	static bool read_key(const std::string& metadata_key_dir, const KeyGeneration& gen,
	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(INFO) << "metadata_key_dir/key: " << dir;
	if (fs_mkdirs(dir.c_str(), 0700)) {
	PLOG(ERROR) << "Creating directories: " << dir;
	return false;
	}
	auto temp = metadata_key_dir + "/tmp";
	auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
	/* If we have a leftover upgraded key, delete it.
	* We either failed an update and must return to the old key,
	* or we rebooted before commiting the keys in a freak accident.
	* Either way, we can re-upgrade the key if we need to.
	*/

	Keymaster keymaster;
	if (pathExists(newKeyPath)) {
	if (!android::base::ReadFileToString(newKeyPath, &sKey))
	LOG(ERROR) << "Failed to read incomplete key: " << dir;
	else if (!keymaster.deleteKey(sKey))
	LOG(ERROR) << "Incomplete key deletion failed, continuing anyway: " << dir;
	else
	unlink(newKeyPath.c_str());
	}
	bool needs_cp = cp_needsCheckpoint();
	if (!retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key, true)) return false;
	if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
	return true;
	}

	static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
	if (::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) {
	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 (options.use_hw_wrapped_key) {
	if (!exportWrappedStorageKey(key, &module_key)) {
	LOG(ERROR) << "Failed to get ephemeral wrapped key";
	return false;
	}
	} else {
	module_key = key;
	}

	KeyBuffer hex_key_buffer;
	if (::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();
	if (options.use_hw_wrapped_key) target->SetWrappedKeyV0();

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

	auto& dm = DeviceMapper::Instance();
	for (int i = 0;; i++) {
	if (dm.CreateDevice(dm_name, table)) {
	break;
	}
	if (i + 1 >= TABLE_LOAD_RETRIES) {
	PLOG(ERROR) << "Could not create default-key device " << dm_name;
	return false;
	}
	PLOG(INFO) << "Could not create default-key device, retrying";
	usleep(500000);
	}

	if (!dm.GetDmDevicePathByName(dm_name, crypto_blkdev)) {
	LOG(ERROR) << "Cannot retrieve default-key device status " << dm_name;
	return false;
	}
	std::stringstream ss;
	ss << *crypto_blkdev;
	LOG(INFO) << "Created device: " << ss.str();
	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->use_hw_wrapped_key = true;
	} else {
	LOG(ERROR) << "Invalid metadata encryption flag: " << parts[1];
	return false;
	}
	}
	return true;
	}

	bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,
	bool needs_encrypt) {
	LOG(INFO) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
	auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
	if (encrypted_state != "" && encrypted_state != "encrypted") {
	LOG(ERROR) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
	return false;
	}
	if (fstab_default.empty()) {
	if (!ReadDefaultFstab(&fstab_default)) {
	PLOG(ERROR) << "Failed to open default fstab";
	return -1;
	}
	}
	auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
	if (!data_rec) {
	LOG(ERROR) << "Failed to get data_rec for " << mount_point;
	return false;
	}

	constexpr unsigned int pre_gki_level = 29;
	unsigned int options_format_version = android::base::GetUintProperty<unsigned int>(
	"ro.crypto.dm_default_key.options_format.version",
	(GetFirstApiLevel() <= pre_gki_level ? 1 : 2));

	CryptoOptions options;
	if (options_format_version == 1) {
	if (!data_rec->metadata_encryption.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.use_hw_wrapped_key = true;
	LOG(INFO) << "metadata_wrapped_key_true";
	}
	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)) return false;
	} else {
	LOG(ERROR) << "Unknown options_format_version: " << options_format_version;
	return false;
	}
	auto gen = needs_encrypt ? makeGen(options) : neverGen();
	KeyBuffer key;
	if (!read_key(data_rec->metadata_key_dir, gen, &key)) return false;

	std::string crypto_blkdev;
	uint64_t nr_sec;
	if (!create_crypto_blk_dev(kDmNameUserdata, blk_device, key, options, &crypto_blkdev, &nr_sec))
	return false;

	// FIXME handle the corrupt case
	if (needs_encrypt) {
	LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
	off64_t size_already_done = 0;
	auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), blk_device.data(), nr_sec,
	&size_already_done, nr_sec, 0, false);
	if (rc != 0) {
	LOG(ERROR) << "Inplace crypto failed with code: " << rc;
	return false;
	}
	if (static_cast<uint64_t>(size_already_done) != nr_sec) {
	LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
	return false;
	}
	LOG(INFO) << "Inplace encryption complete";
	}

	LOG(INFO) << "Mounting metadata-encrypted filesystem:" << mount_point;
	mount_via_fs_mgr(mount_point.c_str(), crypto_blkdev.c_str());
	android::base::SetProperty("ro.crypto.fs_crypto_blkdev", crypto_blkdev);

	// 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(ERROR) << "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);
	}