nextcloud/lib/private/Encryption/Keys/Storage.php

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<?php
/**
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* @copyright Copyright (c) 2016, ownCloud, Inc.
*
* @author Bjoern Schiessle <bjoern@schiessle.org>
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* @author Björn Schießle <bjoern@schiessle.org>
* @author Christoph Wurst <christoph@winzerhof-wurst.at>
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* @author Joas Schilling <coding@schilljs.com>
* @author Roeland Jago Douma <roeland@famdouma.nl>
* @author Thomas Müller <thomas.mueller@tmit.eu>
* @author Vincent Petry <vincent@nextcloud.com>
*
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Encryption\Keys;
use OC\Encryption\Util;
use OC\Files\Filesystem;
use OC\Files\View;
use OC\ServerNotAvailableException;
use OC\User\NoUserException;
use OCP\Encryption\Keys\IStorage;
use OCP\IConfig;
use OCP\Security\ICrypto;
class Storage implements IStorage {
// hidden file which indicate that the folder is a valid key storage
public const KEY_STORAGE_MARKER = '.oc_key_storage';
/** @var View */
private $view;
/** @var Util */
private $util;
// base dir where all the file related keys are stored
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/** @var string */
private $keys_base_dir;
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// root of the key storage default is empty which means that we use the data folder
/** @var string */
private $root_dir;
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/** @var string */
private $encryption_base_dir;
/** @var string */
private $backup_base_dir;
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/** @var array */
private $keyCache = [];
/** @var ICrypto */
private $crypto;
/** @var IConfig */
private $config;
/**
* @param View $view
* @param Util $util
*/
public function __construct(View $view, Util $util, ICrypto $crypto, IConfig $config) {
$this->view = $view;
$this->util = $util;
$this->encryption_base_dir = '/files_encryption';
$this->keys_base_dir = $this->encryption_base_dir .'/keys';
$this->backup_base_dir = $this->encryption_base_dir .'/backup';
$this->root_dir = $this->util->getKeyStorageRoot();
$this->crypto = $crypto;
$this->config = $config;
}
/**
* @inheritdoc
*/
public function getUserKey($uid, $keyId, $encryptionModuleId) {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, $uid);
return base64_decode($this->getKeyWithUid($path, $uid));
}
/**
* @inheritdoc
*/
public function getFileKey($path, $keyId, $encryptionModuleId) {
$realFile = $this->util->stripPartialFileExtension($path);
$keyDir = $this->getFileKeyDir($encryptionModuleId, $realFile);
$key = $this->getKey($keyDir . $keyId)['key'];
if ($key === '' && $realFile !== $path) {
// Check if the part file has keys and use them, if no normal keys
// exist. This is required to fix copyBetweenStorage() when we
// rename a .part file over storage borders.
$keyDir = $this->getFileKeyDir($encryptionModuleId, $path);
$key = $this->getKey($keyDir . $keyId)['key'];
}
return base64_decode($key);
}
/**
* @inheritdoc
*/
public function getSystemUserKey($keyId, $encryptionModuleId) {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, null);
return base64_decode($this->getKeyWithUid($path, null));
}
/**
* @inheritdoc
*/
public function setUserKey($uid, $keyId, $key, $encryptionModuleId) {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, $uid);
return $this->setKey($path, [
'key' => base64_encode($key),
'uid' => $uid,
]);
}
/**
* @inheritdoc
*/
public function setFileKey($path, $keyId, $key, $encryptionModuleId) {
$keyDir = $this->getFileKeyDir($encryptionModuleId, $path);
return $this->setKey($keyDir . $keyId, [
'key' => base64_encode($key),
]);
}
/**
* @inheritdoc
*/
public function setSystemUserKey($keyId, $key, $encryptionModuleId) {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, null);
return $this->setKey($path, [
'key' => base64_encode($key),
'uid' => null,
]);
}
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/**
* @inheritdoc
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*/
public function deleteUserKey($uid, $keyId, $encryptionModuleId) {
try {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, $uid);
return !$this->view->file_exists($path) || $this->view->unlink($path);
} catch (NoUserException $e) {
// this exception can come from initMountPoints() from setupUserMounts()
// for a deleted user.
//
// It means, that:
// - we are not running in alternative storage mode because we don't call
// initMountPoints() in that mode
// - the keys were in the user's home but since the user was deleted, the
// user's home is gone and so are the keys
//
// So there is nothing to do, just ignore.
}
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}
/**
* @inheritdoc
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*/
public function deleteFileKey($path, $keyId, $encryptionModuleId) {
$keyDir = $this->getFileKeyDir($encryptionModuleId, $path);
return !$this->view->file_exists($keyDir . $keyId) || $this->view->unlink($keyDir . $keyId);
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}
/**
* @inheritdoc
*/
public function deleteAllFileKeys($path) {
$keyDir = $this->getFileKeyDir('', $path);
return !$this->view->file_exists($keyDir) || $this->view->deleteAll($keyDir);
}
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/**
* @inheritdoc
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*/
public function deleteSystemUserKey($keyId, $encryptionModuleId) {
$path = $this->constructUserKeyPath($encryptionModuleId, $keyId, null);
return !$this->view->file_exists($path) || $this->view->unlink($path);
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}
/**
* construct path to users key
*
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* @param string $encryptionModuleId
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* @param string $keyId
* @param string $uid
* @return string
*/
protected function constructUserKeyPath($encryptionModuleId, $keyId, $uid) {
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if ($uid === null) {
$path = $this->root_dir . '/' . $this->encryption_base_dir . '/' . $encryptionModuleId . '/' . $keyId;
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} else {
$path = $this->root_dir . '/' . $uid . $this->encryption_base_dir . '/'
. $encryptionModuleId . '/' . $uid . '.' . $keyId;
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}
return \OC\Files\Filesystem::normalizePath($path);
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}
/**
* @param string $path
* @param string|null $uid
* @return string
* @throws ServerNotAvailableException
*
* Small helper function to fetch the key and verify the value for user and system keys
*/
private function getKeyWithUid(string $path, ?string $uid): string {
$data = $this->getKey($path);
if (!isset($data['key'])) {
throw new ServerNotAvailableException('Key is invalid');
}
if ($data['key'] === '') {
return '';
}
if (!array_key_exists('uid', $data) || $data['uid'] !== $uid) {
// If the migration is done we error out
$versionFromBeforeUpdate = $this->config->getSystemValue('version', '0.0.0.0');
if (version_compare($versionFromBeforeUpdate, '20.0.0.1', '<=')) {
return $data['key'];
}
if ($this->config->getSystemValueBool('encryption.key_storage_migrated', true)) {
throw new ServerNotAvailableException('Key has been modified');
} else {
//Otherwise we migrate
$data['uid'] = $uid;
$this->setKey($path, $data);
}
}
return $data['key'];
}
/**
* read key from hard disk
*
* @param string $path to key
* @return array containing key as base64encoded key, and possible the uid
*/
private function getKey($path): array {
$key = [
'key' => '',
];
if ($this->view->file_exists($path)) {
if (isset($this->keyCache[$path])) {
$key = $this->keyCache[$path];
} else {
$data = $this->view->file_get_contents($path);
// Version <20.0.0.1 doesn't have this
$versionFromBeforeUpdate = $this->config->getSystemValue('version', '0.0.0.0');
if (version_compare($versionFromBeforeUpdate, '20.0.0.1', '<=')) {
$key = [
'key' => base64_encode($data),
];
} else {
if ($this->config->getSystemValueBool('encryption.key_storage_migrated', true)) {
try {
$clearData = $this->crypto->decrypt($data);
} catch (\Exception $e) {
throw new ServerNotAvailableException('Could not decrypt key', 0, $e);
}
$dataArray = json_decode($clearData, true);
if ($dataArray === null) {
throw new ServerNotAvailableException('Invalid encryption key');
}
$key = $dataArray;
} else {
/*
* Even if not all keys are migrated we should still try to decrypt it (in case some have moved).
* However it is only a failure now if it is an array and decryption fails
*/
$fallback = false;
try {
$clearData = $this->crypto->decrypt($data);
} catch (\Exception $e) {
$fallback = true;
}
if (!$fallback) {
$dataArray = json_decode($clearData, true);
if ($dataArray === null) {
throw new ServerNotAvailableException('Invalid encryption key');
}
$key = $dataArray;
} else {
$key = [
'key' => base64_encode($data),
];
}
}
}
$this->keyCache[$path] = $key;
}
}
return $key;
}
/**
* write key to disk
*
*
* @param string $path path to key directory
* @param array $key key
* @return bool
*/
private function setKey($path, $key) {
$this->keySetPreparation(dirname($path));
$versionFromBeforeUpdate = $this->config->getSystemValue('version', '0.0.0.0');
if (version_compare($versionFromBeforeUpdate, '20.0.0.1', '<=')) {
// Only store old format if this happens during the migration.
// TODO: Remove for 21
$data = base64_decode($key['key']);
} else {
// Wrap the data
$data = $this->crypto->encrypt(json_encode($key));
}
$result = $this->view->file_put_contents($path, $data);
if (is_int($result) && $result > 0) {
$this->keyCache[$path] = $key;
return true;
}
return false;
}
/**
* get path to key folder for a given file
*
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* @param string $encryptionModuleId
* @param string $path path to the file, relative to data/
* @return string
*/
private function getFileKeyDir($encryptionModuleId, $path) {
list($owner, $filename) = $this->util->getUidAndFilename($path);
// in case of system wide mount points the keys are stored directly in the data directory
if ($this->util->isSystemWideMountPoint($filename, $owner)) {
$keyPath = $this->root_dir . '/' . $this->keys_base_dir . $filename . '/';
} else {
$keyPath = $this->root_dir . '/' . $owner . $this->keys_base_dir . $filename . '/';
}
return Filesystem::normalizePath($keyPath . $encryptionModuleId . '/', false);
}
/**
* move keys if a file was renamed
*
* @param string $source
* @param string $target
* @return boolean
*/
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public function renameKeys($source, $target) {
$sourcePath = $this->getPathToKeys($source);
$targetPath = $this->getPathToKeys($target);
if ($this->view->file_exists($sourcePath)) {
$this->keySetPreparation(dirname($targetPath));
$this->view->rename($sourcePath, $targetPath);
return true;
}
return false;
}
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/**
* copy keys if a file was renamed
*
* @param string $source
* @param string $target
* @return boolean
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*/
public function copyKeys($source, $target) {
$sourcePath = $this->getPathToKeys($source);
$targetPath = $this->getPathToKeys($target);
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if ($this->view->file_exists($sourcePath)) {
$this->keySetPreparation(dirname($targetPath));
$this->view->copy($sourcePath, $targetPath);
return true;
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}
return false;
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}
/**
* backup keys of a given encryption module
*
* @param string $encryptionModuleId
* @param string $purpose
* @param string $uid
* @return bool
* @since 12.0.0
*/
public function backupUserKeys($encryptionModuleId, $purpose, $uid) {
$source = $uid . $this->encryption_base_dir . '/' . $encryptionModuleId;
$backupDir = $uid . $this->backup_base_dir;
if (!$this->view->file_exists($backupDir)) {
$this->view->mkdir($backupDir);
}
$backupDir = $backupDir . '/' . $purpose . '.' . $encryptionModuleId . '.' . $this->getTimestamp();
$this->view->mkdir($backupDir);
return $this->view->copy($source, $backupDir);
}
/**
* get the current timestamp
*
* @return int
*/
protected function getTimestamp() {
return time();
}
/**
* get system wide path and detect mount points
*
* @param string $path
* @return string
*/
protected function getPathToKeys($path) {
list($owner, $relativePath) = $this->util->getUidAndFilename($path);
$systemWideMountPoint = $this->util->isSystemWideMountPoint($relativePath, $owner);
if ($systemWideMountPoint) {
$systemPath = $this->root_dir . '/' . $this->keys_base_dir . $relativePath . '/';
} else {
$systemPath = $this->root_dir . '/' . $owner . $this->keys_base_dir . $relativePath . '/';
}
return Filesystem::normalizePath($systemPath, false);
}
/**
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* Make preparations to filesystem for saving a key file
*
* @param string $path relative to the views root
*/
protected function keySetPreparation($path) {
// If the file resides within a subdirectory, create it
if (!$this->view->file_exists($path)) {
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$sub_dirs = explode('/', ltrim($path, '/'));
$dir = '';
foreach ($sub_dirs as $sub_dir) {
$dir .= '/' . $sub_dir;
if (!$this->view->is_dir($dir)) {
$this->view->mkdir($dir);
}
}
}
}
}