owncloud/core

<?php
/**
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Ilja Neumann <ineumann@owncloud.com>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @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\Files\Cache\Wrapper;

use OCP\Constants;

/**
 * Works together with ReadOnlyJail class
 * to allow file creation outside of users files dir.
 *
 * @package OC\Files\Cache\Wrapper
 */
class ReadOnlyCachePermissionsMask extends CacheWrapper {
    /**
     * @var int
     */
    protected $mask;

    /**
     * System internal paths which should not be protected
     * @var array
     */
    private $whitelist = [
        'uploads',
        'cache',
        'files_zsync'
    ];

    /**
     * @param \OCP\Files\Cache\ICache $cache
     * @param int $mask
     */
    public function __construct($cache, $mask) {
        parent::__construct($cache);
        $this->mask = $mask;
    }

    /**
     * @param \OCP\Files\Cache\ICacheEntry $entry
     * @return \OCP\Files\Cache\ICacheEntry
     */
    protected function formatCacheEntry($entry) {
        $storageId = $entry->getStorageId();

        // Give all permissions to whitelisted "internal" paths and their
        // subdirectories
        if ($this->isHomeStorage($storageId)) {
            foreach ($this->whitelist as $path) {
                if ($this->startsWith($entry->getPath(), $path)) {
                    $entry['permissions'] = Constants::PERMISSION_ALL;
                    return $entry;
                }
            }
        }

        // Allow creation of skeleton files
        if ($this->isHomeStorage($storageId) && $entry->getPath() === '') {
            $entry['permissions'] = Constants::PERMISSION_CREATE;
            $this->mask = Constants::PERMISSION_CREATE;
        }

        $entry['permissions'] &= $this->mask;
        return $entry;
    }

    private function isHomeStorage($storageId) {
        return $this->startsWith($storageId, 'home::') ||
            $this->startsWith($storageId, 'object::');
    }

    private function startsWith($haystack, $needle) {
        return (\strpos($haystack, $needle) === 0);
    }
}