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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_KEYUTIL_H
#define ANDROID_VOLD_KEYUTIL_H
#include "KeyBuffer.h"
#include "KeyStorage.h"
#include <fscrypt/fscrypt.h>
#include <memory>
#include <string>
namespace android {
namespace vold {
// Description of how to generate a key when needed.
struct KeyGeneration {
size_t keysize;
bool allow_gen;
bool use_hw_wrapped_key;
};
// Generate a key as specified in KeyGeneration
bool generateStorageKey(const KeyGeneration& gen, KeyBuffer* key);
// Returns a key with allow_gen false so generateStorageKey returns false;
// this is used to indicate to retrieveOrGenerateKey that a key should not
// be generated.
const KeyGeneration neverGen();
bool isFsKeyringSupported(void);
// Install a file-based encryption key to the kernel, for use by encrypted files
// on the specified filesystem using the specified encryption policy version.
//
// For v1 policies, we use FS_IOC_ADD_ENCRYPTION_KEY if the kernel supports it.
// Otherwise we add the key to the global session keyring as a "logon" key.
//
// For v2 policies, we always use FS_IOC_ADD_ENCRYPTION_KEY; it's the only way
// the kernel supports.
//
// If kernel supports FS_IOC_ADD_ENCRYPTION_KEY, also installs key of
// fscrypt-provisioning type to the global session keyring. This makes it
// possible to unmount and then remount mountpoint without losing the file-based
// key.
//
// Returns %true on success, %false on failure. On success also sets *policy
// to the EncryptionPolicy used to refer to this key.
bool installKey(const std::string& mountpoint, const android::fscrypt::EncryptionOptions& options,
const KeyBuffer& key, android::fscrypt::EncryptionPolicy* policy);
// Evict a file-based encryption key from the kernel.
//
// This undoes the effect of installKey().
//
// If the kernel doesn't support the filesystem-level keyring, the caller is
// responsible for dropping caches.
bool evictKey(const std::string& mountpoint, const android::fscrypt::EncryptionPolicy& policy);
// Retrieves the key from the named directory, or generates it if it doesn't
// exist.
bool retrieveOrGenerateKey(const std::string& key_path, const std::string& tmp_path,
const KeyAuthentication& key_authentication, const KeyGeneration& gen,
KeyBuffer* key);
// Re-installs a file-based encryption key of fscrypt-provisioning type from the
// global session keyring back into fs keyring of the mountpoint.
bool reloadKeyFromSessionKeyring(const std::string& mountpoint,
const android::fscrypt::EncryptionPolicy& policy);
} // namespace vold
} // namespace android
#endif