cbc1bdba59
Currently, the vold detects the factory reset by checking the metadata encryption key. This logic is only valid when the device is not in DSU mode. Bug: 199222795 Test: run DSU installation on a Pixel device Change-Id: Ib40bd44d2ef7c872eba177c9ccfefac8934a49e6
360 lines
13 KiB
C++
360 lines
13 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "MetadataCrypt.h"
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#include "KeyBuffer.h"
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#include <string>
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#include <fcntl.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <android-base/strings.h>
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#include <android-base/unique_fd.h>
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#include <cutils/fs.h>
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#include <fs_mgr.h>
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#include <libdm/dm.h>
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#include <libgsi/libgsi.h>
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#include "Checkpoint.h"
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#include "CryptoType.h"
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#include "EncryptInplace.h"
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#include "KeyStorage.h"
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#include "KeyUtil.h"
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#include "Keystore.h"
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#include "Utils.h"
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#include "VoldUtil.h"
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#include "fs/Ext4.h"
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#include "fs/F2fs.h"
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namespace android {
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namespace vold {
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using android::fs_mgr::FstabEntry;
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using android::fs_mgr::GetEntryForMountPoint;
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using android::fscrypt::GetFirstApiLevel;
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using android::vold::KeyBuffer;
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using namespace android::dm;
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// Parsed from metadata options
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struct CryptoOptions {
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struct CryptoType cipher = invalid_crypto_type;
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bool use_legacy_options_format = false;
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bool set_dun = true; // Non-legacy driver always sets DUN
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bool use_hw_wrapped_key = false;
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};
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static const std::string kDmNameUserdata = "userdata";
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// The first entry in this table is the default crypto type.
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constexpr CryptoType supported_crypto_types[] = {aes_256_xts, adiantum};
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static_assert(validateSupportedCryptoTypes(64, supported_crypto_types,
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array_length(supported_crypto_types)),
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"We have a CryptoType which was incompletely constructed.");
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constexpr CryptoType legacy_aes_256_xts =
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CryptoType().set_config_name("aes-256-xts").set_kernel_name("AES-256-XTS").set_keysize(64);
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static_assert(isValidCryptoType(64, legacy_aes_256_xts),
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"We have a CryptoType which was incompletely constructed.");
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// Returns KeyGeneration suitable for key as described in CryptoOptions
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const KeyGeneration makeGen(const CryptoOptions& options) {
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return KeyGeneration{options.cipher.get_keysize(), true, options.use_hw_wrapped_key};
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}
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static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
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// fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
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// partitions in the fsck domain.
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if (setexeccon(android::vold::sFsckContext)) {
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PLOG(ERROR) << "Failed to setexeccon";
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return false;
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}
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auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
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const_cast<char*>(blk_device), nullptr,
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android::vold::cp_needsCheckpoint(), true);
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if (setexeccon(nullptr)) {
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PLOG(ERROR) << "Failed to clear setexeccon";
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return false;
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}
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if (mount_rc != 0) {
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LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;
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return false;
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}
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LOG(DEBUG) << "Mounted " << mount_point;
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return true;
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}
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static bool read_key(const std::string& metadata_key_dir, const KeyGeneration& gen,
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KeyBuffer* key) {
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if (metadata_key_dir.empty()) {
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LOG(ERROR) << "Failed to get metadata_key_dir";
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return false;
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}
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std::string sKey;
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auto dir = metadata_key_dir + "/key";
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LOG(DEBUG) << "metadata_key_dir/key: " << dir;
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if (!MkdirsSync(dir, 0700)) return false;
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auto in_dsu = android::base::GetBoolProperty("ro.gsid.image_running", false);
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// !pathExists(dir) does not imply there's a factory reset when in DSU mode.
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if (!pathExists(dir) && !in_dsu) {
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auto delete_all = android::base::GetBoolProperty(
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"ro.crypto.metadata_init_delete_all_keys.enabled", false);
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if (delete_all) {
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LOG(INFO) << "Metadata key does not exist, calling deleteAllKeys";
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Keystore::deleteAllKeys();
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} else {
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LOG(DEBUG) << "Metadata key does not exist but "
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"ro.crypto.metadata_init_delete_all_keys.enabled is false";
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}
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}
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auto temp = metadata_key_dir + "/tmp";
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return retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key);
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}
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static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
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if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
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PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
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return false;
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}
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return true;
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}
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static bool create_crypto_blk_dev(const std::string& dm_name, const std::string& blk_device,
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const KeyBuffer& key, const CryptoOptions& options,
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std::string* crypto_blkdev, uint64_t* nr_sec) {
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if (!get_number_of_sectors(blk_device, nr_sec)) return false;
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// TODO(paulcrowley): don't hardcode that DmTargetDefaultKey uses 4096-byte
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// sectors
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*nr_sec &= ~7;
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KeyBuffer module_key;
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if (options.use_hw_wrapped_key) {
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if (!exportWrappedStorageKey(key, &module_key)) {
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LOG(ERROR) << "Failed to get ephemeral wrapped key";
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return false;
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}
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} else {
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module_key = key;
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}
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KeyBuffer hex_key_buffer;
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if (android::vold::StrToHex(module_key, hex_key_buffer) != android::OK) {
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LOG(ERROR) << "Failed to turn key to hex";
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return false;
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}
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std::string hex_key(hex_key_buffer.data(), hex_key_buffer.size());
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auto target = std::make_unique<DmTargetDefaultKey>(0, *nr_sec, options.cipher.get_kernel_name(),
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hex_key, blk_device, 0);
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if (options.use_legacy_options_format) target->SetUseLegacyOptionsFormat();
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if (options.set_dun) target->SetSetDun();
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if (options.use_hw_wrapped_key) target->SetWrappedKeyV0();
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DmTable table;
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table.AddTarget(std::move(target));
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auto& dm = DeviceMapper::Instance();
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if (!dm.CreateDevice(dm_name, table, crypto_blkdev, std::chrono::seconds(5))) {
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PLOG(ERROR) << "Could not create default-key device " << dm_name;
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return false;
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}
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return true;
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}
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static const CryptoType& lookup_cipher(const std::string& cipher_name) {
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if (cipher_name.empty()) return supported_crypto_types[0];
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for (size_t i = 0; i < array_length(supported_crypto_types); i++) {
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if (cipher_name == supported_crypto_types[i].get_config_name()) {
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return supported_crypto_types[i];
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}
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}
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return invalid_crypto_type;
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}
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static bool parse_options(const std::string& options_string, CryptoOptions* options) {
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auto parts = android::base::Split(options_string, ":");
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if (parts.size() < 1 || parts.size() > 2) {
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LOG(ERROR) << "Invalid metadata encryption option: " << options_string;
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return false;
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}
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std::string cipher_name = parts[0];
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options->cipher = lookup_cipher(cipher_name);
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if (options->cipher.get_kernel_name() == nullptr) {
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LOG(ERROR) << "No metadata cipher named " << cipher_name << " found";
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return false;
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}
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if (parts.size() == 2) {
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if (parts[1] == "wrappedkey_v0") {
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options->use_hw_wrapped_key = true;
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} else {
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LOG(ERROR) << "Invalid metadata encryption flag: " << parts[1];
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return false;
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}
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}
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return true;
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}
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bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,
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bool needs_encrypt, bool should_format,
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const std::string& fs_type) {
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LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point
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<< " encrypt: " << needs_encrypt << " format: " << should_format << " with "
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<< fs_type;
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auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
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if (encrypted_state != "" && encrypted_state != "encrypted") {
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LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
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return false;
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}
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auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
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if (!data_rec) {
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LOG(ERROR) << "Failed to get data_rec for " << mount_point;
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return false;
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}
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unsigned int options_format_version = android::base::GetUintProperty<unsigned int>(
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"ro.crypto.dm_default_key.options_format.version",
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(GetFirstApiLevel() <= __ANDROID_API_Q__ ? 1 : 2));
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CryptoOptions options;
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if (options_format_version == 1) {
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if (!data_rec->metadata_encryption.empty()) {
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LOG(ERROR) << "metadata_encryption options cannot be set in legacy mode";
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return false;
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}
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options.cipher = legacy_aes_256_xts;
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options.use_legacy_options_format = true;
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options.set_dun = android::base::GetBoolProperty("ro.crypto.set_dun", false);
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if (!options.set_dun && data_rec->fs_mgr_flags.checkpoint_blk) {
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LOG(ERROR)
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<< "Block checkpoints and metadata encryption require ro.crypto.set_dun option";
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return false;
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}
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} else if (options_format_version == 2) {
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if (!parse_options(data_rec->metadata_encryption, &options)) return false;
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} else {
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LOG(ERROR) << "Unknown options_format_version: " << options_format_version;
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return false;
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}
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auto gen = needs_encrypt ? makeGen(options) : neverGen();
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KeyBuffer key;
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if (!read_key(data_rec->metadata_key_dir, gen, &key)) return false;
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std::string crypto_blkdev;
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uint64_t nr_sec;
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if (!create_crypto_blk_dev(kDmNameUserdata, blk_device, key, options, &crypto_blkdev, &nr_sec))
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return false;
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if (needs_encrypt) {
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if (should_format) {
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status_t error;
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if (fs_type == "ext4") {
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error = ext4::Format(crypto_blkdev, 0, mount_point);
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} else if (fs_type == "f2fs") {
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error = f2fs::Format(crypto_blkdev);
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} else {
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LOG(ERROR) << "Unknown filesystem type: " << fs_type;
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return false;
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}
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LOG(DEBUG) << "Format (err=" << error << ") " << crypto_blkdev << " on " << mount_point;
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if (error != 0) return false;
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} else {
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if (!encrypt_inplace(crypto_blkdev, blk_device, nr_sec, false)) return false;
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}
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}
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LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
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mount_via_fs_mgr(mount_point.c_str(), crypto_blkdev.c_str());
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// Record that there's at least one fstab entry with metadata encryption
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if (!android::base::SetProperty("ro.crypto.metadata.enabled", "true")) {
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LOG(WARNING) << "failed to set ro.crypto.metadata.enabled"; // This isn't fatal
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}
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return true;
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}
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static bool get_volume_options(CryptoOptions* options) {
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return parse_options(android::base::GetProperty("ro.crypto.volume.metadata.encryption", ""),
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options);
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}
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bool defaultkey_volume_keygen(KeyGeneration* gen) {
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CryptoOptions options;
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if (!get_volume_options(&options)) return false;
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*gen = makeGen(options);
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return true;
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}
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bool defaultkey_setup_ext_volume(const std::string& label, const std::string& blk_device,
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const KeyBuffer& key, std::string* out_crypto_blkdev) {
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LOG(DEBUG) << "defaultkey_setup_ext_volume: " << label << " " << blk_device;
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CryptoOptions options;
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if (!get_volume_options(&options)) return false;
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uint64_t nr_sec;
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return create_crypto_blk_dev(label, blk_device, key, options, out_crypto_blkdev, &nr_sec);
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}
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bool destroy_dsu_metadata_key(const std::string& dsu_slot) {
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LOG(DEBUG) << "destroy_dsu_metadata_key: " << dsu_slot;
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const auto dsu_metadata_key_dir = android::gsi::GetDsuMetadataKeyDir(dsu_slot);
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if (!pathExists(dsu_metadata_key_dir)) {
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LOG(DEBUG) << "DSU metadata_key_dir doesn't exist, nothing to remove: "
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<< dsu_metadata_key_dir;
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return true;
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}
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// Ensure that the DSU key directory is different from the host OS'.
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// Under normal circumstances, this should never happen, but handle it just in case.
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if (auto data_rec = GetEntryForMountPoint(&fstab_default, "/data")) {
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if (dsu_metadata_key_dir == data_rec->metadata_key_dir) {
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LOG(ERROR) << "DSU metadata_key_dir is same as host OS: " << dsu_metadata_key_dir;
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return false;
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}
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}
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bool ok = true;
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for (auto suffix : {"/key", "/tmp"}) {
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const auto key_path = dsu_metadata_key_dir + suffix;
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if (pathExists(key_path)) {
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LOG(DEBUG) << "Destroy key: " << key_path;
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if (!android::vold::destroyKey(key_path)) {
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LOG(ERROR) << "Failed to destroyKey(): " << key_path;
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ok = false;
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}
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}
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}
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if (!ok) {
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return false;
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}
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LOG(DEBUG) << "Remove DSU metadata_key_dir: " << dsu_metadata_key_dir;
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// DeleteDirContentsAndDir() already logged any error, so don't log repeatedly.
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return android::vold::DeleteDirContentsAndDir(dsu_metadata_key_dir) == android::OK;
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}
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} // namespace vold
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} // namespace android
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