48aa90cd6b
fs_mgr may put other dm devices on top of the raw disk, such as for checkpointing, and it hands metadata encryption the uppermost device in vdc. That's what should be encrypted, not the raw disk. Bug: 150354860 Test: Treehugger Change-Id: I279f087b1b7aded40c5a62281154851ce970ba70
365 lines
13 KiB
C++
365 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 <algorithm>
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#include <string>
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#include <thread>
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#include <vector>
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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/file.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 "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 "Keymaster.h"
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#include "Utils.h"
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#include "VoldUtil.h"
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#define TABLE_LOAD_RETRIES 10
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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::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 is_legacy = 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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static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
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static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
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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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// We're about to mount data not verified by verified boot. Tell Keymaster that early boot has
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// ended.
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//
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// TODO(paulcrowley): Make a Keymaster singleton or something, so we don't have to repeatedly
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// open and initialize the service.
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::android::vold::Keymaster keymaster;
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keymaster.earlyBootEnded();
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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());
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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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// Note: It is possible to orphan a key if it is removed before deleting
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// Update this once keymaster APIs change, and we have a proper commit.
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static void commit_key(const std::string& dir) {
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while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
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LOG(ERROR) << "Wait for boot timed out";
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}
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Keymaster keymaster;
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auto keyPath = dir + "/" + kFn_keymaster_key_blob;
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auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
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std::string key;
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if (!android::base::ReadFileToString(keyPath, &key)) {
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LOG(ERROR) << "Failed to read old key: " << dir;
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return;
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}
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if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
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PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
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return;
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}
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if (!keymaster.deleteKey(key)) {
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LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
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}
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LOG(INFO) << "Old Key deleted: " << dir;
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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 (fs_mkdirs(dir.c_str(), 0700)) {
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PLOG(ERROR) << "Creating directories: " << dir;
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return false;
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}
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auto temp = metadata_key_dir + "/tmp";
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auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
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/* If we have a leftover upgraded key, delete it.
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* We either failed an update and must return to the old key,
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* or we rebooted before commiting the keys in a freak accident.
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* Either way, we can re-upgrade the key if we need to.
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*/
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Keymaster keymaster;
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if (pathExists(newKeyPath)) {
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if (!android::base::ReadFileToString(newKeyPath, &sKey))
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LOG(ERROR) << "Failed to read incomplete key: " << dir;
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else if (!keymaster.deleteKey(sKey))
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LOG(ERROR) << "Incomplete key deletion failed, continuing anyway: " << dir;
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else
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unlink(newKeyPath.c_str());
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}
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bool needs_cp = cp_needsCheckpoint();
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if (!retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key, needs_cp)) return false;
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if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
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return true;
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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.is_legacy) target->SetIsLegacy();
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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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for (int i = 0;; i++) {
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if (dm.CreateDevice(dm_name, table)) {
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break;
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}
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if (i + 1 >= TABLE_LOAD_RETRIES) {
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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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PLOG(INFO) << "Could not create default-key device, retrying";
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usleep(500000);
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}
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if (!dm.GetDmDevicePathByName(dm_name, crypto_blkdev)) {
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LOG(ERROR) << "Cannot retrieve default-key device status " << 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) {
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LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
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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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bool is_legacy;
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if (!DmTargetDefaultKey::IsLegacy(&is_legacy)) return false;
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CryptoOptions options;
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if (is_legacy) {
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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.is_legacy = 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 {
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if (!parse_options(data_rec->metadata_encryption, &options)) 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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// FIXME handle the corrupt case
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if (needs_encrypt) {
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LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
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off64_t size_already_done = 0;
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auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), blk_device.data(), nr_sec,
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&size_already_done, nr_sec, 0, false);
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if (rc != 0) {
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LOG(ERROR) << "Inplace crypto failed with code: " << rc;
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return false;
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}
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if (static_cast<uint64_t>(size_already_done) != nr_sec) {
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LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
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return false;
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}
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LOG(INFO) << "Inplace encryption complete";
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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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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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} // namespace vold
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} // namespace android
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