Merge pull request #18482 from owncloud/encrypt-session-data

Add a session wrapper to encrypt the data before storing it on disk

3 files changed, 283 insertions, 1 deletions

diff --git a/lib/private/server.php b/lib/private/server.php
index ff78536cec0..91ffe1b5e4c 100644
--- a/lib/private/server.php
+++ b/lib/private/server.php
@@ -40,6 +40,7 @@ use bantu\IniGetWrapper\IniGetWrapper;
 use OC\AppFramework\Http\Request;
 use OC\AppFramework\Db\Db;
 use OC\AppFramework\Utility\SimpleContainer;
+use OC\AppFramework\Utility\TimeFactory;
 use OC\Command\AsyncBus;
 use OC\Diagnostics\EventLogger;
 use OC\Diagnostics\NullEventLogger;
@@ -56,6 +57,7 @@ use OC\Security\Crypto;
 use OC\Security\Hasher;
 use OC\Security\SecureRandom;
 use OC\Security\TrustedDomainHelper;
+use OC\Session\CryptoWrapper;
 use OC\Tagging\TagMapper;
 use OCP\IServerContainer;
 use Symfony\Component\EventDispatcher\EventDispatcher;
@@ -159,7 +161,12 @@ class Server extends SimpleContainer implements IServerContainer {
 		});
 		$this->registerService('UserSession', function (Server $c) {
 			$manager = $c->getUserManager();
-			$userSession = new \OC\User\Session($manager, new \OC\Session\Memory(''));
+
+			$session = new \OC\Session\Memory('');
+			$cryptoWrapper = $c->getSessionCryptoWrapper();
+			$session = $cryptoWrapper->wrapSession($session);
+
+			$userSession = new \OC\User\Session($manager, $session);
 			$userSession->listen('\OC\User', 'preCreateUser', function ($uid, $password) {
 				\OC_Hook::emit('OC_User', 'pre_createUser', array('run' => true, 'uid' => $uid, 'password' => $password));
 			});
@@ -462,6 +469,31 @@ class Server extends SimpleContainer implements IServerContainer {
 		$this->registerService('EventDispatcher', function() {
 			return new EventDispatcher();
 		});
+		$this->registerService('CryptoWrapper', function (Server $c) {
+			// FIXME: Instantiiated here due to cyclic dependency
+			$request = new Request(
+				[
+					'get' => $_GET,
+					'post' => $_POST,
+					'files' => $_FILES,
+					'server' => $_SERVER,
+					'env' => $_ENV,
+					'cookies' => $_COOKIE,
+					'method' => (isset($_SERVER) && isset($_SERVER['REQUEST_METHOD']))
+						? $_SERVER['REQUEST_METHOD']
+						: null,
+				],
+				new SecureRandom(),
+				$c->getConfig()
+			);
+
+			return new CryptoWrapper(
+				$c->getConfig(),
+				$c->getCrypto(),
+				$c->getSecureRandom(),
+				$request
+			);
+		});
 	}
 
 	/**
@@ -977,4 +1009,11 @@ class Server extends SimpleContainer implements IServerContainer {
 	public function getEventDispatcher() {
 		return $this->query('EventDispatcher');
 	}
+
+	/**
+	 * @return \OC\Session\CryptoWrapper
+	 */
+	public function getSessionCryptoWrapper() {
+		return $this->query('CryptoWrapper');
+	}
 }
diff --git a/lib/private/session/cryptosessiondata.php b/lib/private/session/cryptosessiondata.php
new file mode 100644
index 00000000000..60d22b25e97
--- /dev/null
+++ b/lib/private/session/cryptosessiondata.php
@@ -0,0 +1,147 @@
+<?php
+/**
+ * @author Joas Schilling <nickvergessen@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Session;
+
+use OCP\ISession;
+use OCP\Security\ICrypto;
+
+/**
+ * Class CryptoSessionData
+ *
+ * @package OC\Session
+ */
+class CryptoSessionData implements \ArrayAccess, ISession {
+	/** @var ISession */
+	protected $session;
+
+	/** @var \OCP\Security\ICrypto */
+	protected $crypto;
+
+	/** @var string */
+	protected $passphrase;
+
+	/**
+	 * @param ISession $session
+	 * @param ICrypto $crypto
+	 * @param string $passphrase
+	 */
+	public function __construct(ISession $session, ICrypto $crypto, $passphrase) {
+		$this->crypto = $crypto;
+		$this->session = $session;
+		$this->passphrase = $passphrase;
+	}
+
+	/**
+	 * Set a value in the session
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 */
+	public function set($key, $value) {
+		$encryptedValue = $this->crypto->encrypt(json_encode($value), $this->passphrase);
+		$this->session->set($key, $encryptedValue);
+	}
+
+	/**
+	 * Get a value from the session
+	 *
+	 * @param string $key
+	 * @return string|null Either the value or null
+	 */
+	public function get($key) {
+		$encryptedValue = $this->session->get($key);
+		if ($encryptedValue === null) {
+			return null;
+		}
+
+		try {
+			$value = $this->crypto->decrypt($encryptedValue, $this->passphrase);
+			return json_decode($value);
+		} catch (\Exception $e) {
+			return null;
+		}
+	}
+
+	/**
+	 * Check if a named key exists in the session
+	 *
+	 * @param string $key
+	 * @return bool
+	 */
+	public function exists($key) {
+		return $this->session->exists($key);
+	}
+
+	/**
+	 * Remove a $key/$value pair from the session
+	 *
+	 * @param string $key
+	 */
+	public function remove($key) {
+		$this->session->remove($key);
+	}
+
+	/**
+	 * Reset and recreate the session
+	 */
+	public function clear() {
+		$this->session->clear();
+	}
+
+	/**
+	 * Close the session and release the lock
+	 */
+	public function close() {
+		$this->session->close();
+	}
+
+	/**
+	 * @param mixed $offset
+	 * @return bool
+	 */
+	public function offsetExists($offset) {
+		return $this->exists($offset);
+	}
+
+	/**
+	 * @param mixed $offset
+	 * @return mixed
+	 */
+	public function offsetGet($offset) {
+		return $this->get($offset);
+	}
+
+	/**
+	 * @param mixed $offset
+	 * @param mixed $value
+	 */
+	public function offsetSet($offset, $value) {
+		$this->set($offset, $value);
+	}
+
+	/**
+	 * @param mixed $offset
+	 */
+	public function offsetUnset($offset) {
+		$this->remove($offset);
+	}
+}
diff --git a/lib/private/session/cryptowrapper.php b/lib/private/session/cryptowrapper.php
new file mode 100644
index 00000000000..62bdcbfb719
--- /dev/null
+++ b/lib/private/session/cryptowrapper.php
@@ -0,0 +1,96 @@
+<?php
+/**
+ * @author Joas Schilling <nickvergessen@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @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\Session;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
+use OCP\IRequest;
+use OCP\ISession;
+use OCP\Security\ICrypto;
+use OCP\Security\ISecureRandom;
+
+/**
+ * Class CryptoWrapper provides some rough basic level of additional security by
+ * storing the session data in an encrypted form.
+ *
+ * The content of the session is encrypted using another cookie sent by the browser.
+ * One should note that an adversary with access to the source code or the system
+ * memory is still able to read the original session ID from the users' request.
+ * This thus can not be considered a strong security measure one should consider
+ * it as an additional small security obfuscation layer to comply with compliance
+ * guidelines.
+ *
+ * TODO: Remove this in a future relase with an approach such as
+ * https://github.com/owncloud/core/pull/17866
+ *
+ * @package OC\Session
+ */
+class CryptoWrapper {
+	const COOKIE_NAME = 'oc_sessionPassphrase';
+
+	/** @var ISession */
+	protected $session;
+
+	/** @var \OCP\Security\ICrypto */
+	protected $crypto;
+
+	/** @var ISecureRandom */
+	protected $random;
+
+	/**
+	 * @param IConfig $config
+	 * @param ICrypto $crypto
+	 * @param ISecureRandom $random
+	 * @param IRequest $request
+	 */
+	public function __construct(IConfig $config,
+								ICrypto $crypto,
+								ISecureRandom $random,
+								IRequest $request) {
+		$this->crypto = $crypto;
+		$this->config = $config;
+		$this->random = $random;
+
+		if (!is_null($request->getCookie(self::COOKIE_NAME))) {
+			$this->passphrase = $request->getCookie(self::COOKIE_NAME);
+		} else {
+			$this->passphrase = $this->random->getMediumStrengthGenerator()->generate(128);
+			$secureCookie = $request->getServerProtocol() === 'https';
+			// FIXME: Required for CI
+			if (!defined('PHPUNIT_RUN')) {
+				setcookie(self::COOKIE_NAME, $this->passphrase, 0, \OC::$WEBROOT, '', $secureCookie, true);
+			}
+		}
+	}
+
+	/**
+	 * @param ISession $session
+	 * @return ISession
+	 */
+	public function wrapSession(ISession $session) {
+		if (!($session instanceof CryptoSessionData)) {
+			return new CryptoSessionData($session, $this->crypto, $this->passphrase);
+		}
+
+		return $session;
+	}
+}