platform_system_vold/KeyUtil.h
Eric Biggers 0e87a83cba vold: remove session keyring workaround for old kernels
The android-4.14-stable and later kernels support the
FS_IOC_ADD_ENCRYPTION_KEY and FS_IOC_REMOVE_ENCRYPTION_KEY ioctls.  This
has superseded the old way of adding fscrypt keys to the kernel, which
was to use the add_key() syscall to add keys to the "session" keyring.
On kernels that support the ioctls, Android doesn't use the obsolete
way.  Since upgrading even just to Android 14 requires at minimum a
android-4.14-stable kernel (according to
https://source.android.com/docs/core/architecture/kernel/android-common#compatibility-matrix),
there is no need to support the obsolete way anymore.

Therefore, this commit removes the code that added and removed keys
to/from the session keyring.  Now the ioctls are used unconditionally.

Flag: N/A for the following reasons:
      - Removing obsolete code, which is fairly safe
      - Very early code, so runtime flag cannot be used
      - This topic also removes code from init, which cannot use aconfig
        libraries because they do not support recovery_available

Bug: 311736104
Test: Build and boot Cuttlefish
Change-Id: I0d9abbda77b1ac838ea6f014dbe22ab032c0e5ae
2023-12-05 19:39:33 +00:00

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2.2 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_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();
// Install a file-based encryption key to the kernel, for use by encrypted files
// on the specified filesystem using the specified encryption policy version.
//
// 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.
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);
} // namespace vold
} // namespace android
#endif