platform_system_vold/KeyUtil.h
Nikita Ioffe 1ee35cf002 fskeyring & userspace reboot: support CE keys
During userspace reboot /data might be unmounted & remounted, meaning
that CE keys stored in fs-level keyring will be lost. In order to be
able to restore them, when installing new key to fs-level keyring, it's
also added to session-level keyring with type "fscrypt-provisioning".

Then when init_user0 is called during userspace reboot, vold will try to
load CE keys from the session-level keyring back into fs-level keyring
for all the users that were unlocked before the reboot.

If for any user vold fails to install the key, init_user0 will fail and
fallback to hard reboot will be triggered.

Test: set a pin pattern
Test: adb shell setprop sys.init.userdata_remount.force_umount 1
Test: adb shell svc power reboot userspace
Test: atest CtsUserspaceRebootHostSideTestCases
Bug: 143970043
Change-Id: I37603dc136c7ededc7b0381e4d730cb0ffd912b4
2020-03-07 01:19:42 +00:00

88 lines
3.1 KiB
C++

/*
* 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 {
using namespace android::fscrypt;
// 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 EncryptionOptions& options,
const KeyBuffer& key, 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 EncryptionPolicy& policy);
bool retrieveOrGenerateKey(const std::string& key_path, const std::string& tmp_path,
const KeyAuthentication& key_authentication, const KeyGeneration& gen,
KeyBuffer* key, bool keepOld = true);
// 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 EncryptionPolicy& policy);
} // namespace vold
} // namespace android
#endif