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/*
* 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 (!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 (!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);
}