platform_system_vold/KeyStorage.h
Satya Tangirala 0f890a93e1 Always use RenameKeyDir() when moving/renaming key directories
Make fixate_user_ce_key() use RenameKeyDir() to rename key directories
so that any deferred commits for these directories are also updated
appropriately.

This fixes a potential lost Keymaster key upgrade if a key were to be
re-wrapped while a user data checkpoint is pending.  This isn't a huge
issue as the key will just get upgraded again, but this should be fixed.

[ebiggers@ - cleaned up slightly from satyat@'s original change]

Bug: 190398249
Change-Id: Ic6c5b4468d07ab335368e3d373916145d096af01
2021-06-08 15:57:31 -07:00

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3 KiB
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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.
*/
#ifndef ANDROID_VOLD_KEYSTORAGE_H
#define ANDROID_VOLD_KEYSTORAGE_H
#include "KeyBuffer.h"
#include <cstdint>
#include <string>
#include <vector>
namespace android {
namespace vold {
// Represents the information needed to decrypt a disk encryption key.
class KeyAuthentication {
public:
KeyAuthentication(const std::string& s) : secret{s} {};
bool usesKeymaster() const { return secret.empty(); };
const std::string secret;
};
extern const KeyAuthentication kEmptyAuthentication;
bool createSecdiscardable(const std::string& path, std::string* hash);
bool readSecdiscardable(const std::string& path, std::string* hash);
// Renames a key directory while also managing deferred commits appropriately.
// This method should be used whenever a key directory needs to be moved/renamed.
bool RenameKeyDir(const std::string& old_name, const std::string& new_name);
// Create a directory at the named path, and store "key" in it,
// in such a way that it can only be retrieved via Keymaster and
// can be securely deleted.
// It's safe to move/rename the directory after creation.
bool storeKey(const std::string& dir, const KeyAuthentication& auth, const KeyBuffer& key);
// Create a directory at the named path, and store "key" in it as storeKey
// This version creates the key in "tmp_path" then atomically renames "tmp_path"
// to "key_path" thereby ensuring that the key is either stored entirely or
// not at all. All the needed files and directories are also fsync'ed to ensure
// that the key is actually persisted to disk.
bool storeKeyAtomically(const std::string& key_path, const std::string& tmp_path,
const KeyAuthentication& auth, const KeyBuffer& key);
// Retrieve the key from the named directory.
bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key);
// Securely destroy the key stored in the named directory and delete the directory.
bool destroyKey(const std::string& dir);
bool runSecdiscardSingle(const std::string& file);
// Generate wrapped storage key using keymaster. Uses STORAGE_KEY tag in keymaster.
bool generateWrappedStorageKey(KeyBuffer* key);
// Export the per-boot boot wrapped storage key using keymaster.
bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key);
// Set a seed to be mixed into all key storage encryption keys.
bool setKeyStorageBindingSeed(const std::vector<uint8_t>& seed);
} // namespace vold
} // namespace android
#endif