Store credentials only in session if required

apps/files_external/lib/smb_oc.php

@@ -13,12 +13,16 @@
 class SMB_OC extends \OC\Files\Storage\SMB {
 	private $username_as_share;
 
+	/**
+	 * @param array $params
+	 * @throws \Exception
+	 */
 	public function __construct($params) {
 		if (isset($params['host']) && \OC::$session->exists('smb-credentials')) {
 			$host=$params['host'];
 			$this->username_as_share = ($params['username_as_share'] === 'true');
 
-			$params_auth = \OC::$session->get('smb-credentials');
+			$params_auth = json_decode(\OC::$server->getCrypto()->decrypt(\OC::$session->get('smb-credentials')), true);
 			$user = \OC::$session->get('loginname');
 			$password = $params_auth['password'];
 
@@ -44,14 +48,34 @@ public function __construct($params) {
 		}
 	}
 
-	public static function login( $params ) {
-		\OC::$session->set('smb-credentials', $params);
+	/**
+	 * Intercepts the user credentials on login and stores them
+	 * encrypted inside the session if SMB_OC storage is enabled.
+	 * @param array $params
+	 */
+	public static function login($params) {
+		$mountpoints = \OC_Mount_Config::getAbsoluteMountPoints($params['uid']);
+		$mountpointClasses = array();
+		foreach($mountpoints as $mountpoint) {
+			$mountpointClasses[$mountpoint['class']] = true;
+		}
+		if(isset($mountpointClasses['\OC\Files\Storage\SMB_OC'])) {
+			\OC::$session->set('smb-credentials', \OC::$server->getCrypto()->encrypt(json_encode($params)));
+		}
 	}
 
+	/**
+	 * @param string $path
+	 * @return boolean
+	 */
 	public function isSharable($path) {
 		return false;
 	}
 
+	/**
+	 * @param bool $isPersonal
+	 * @return bool
+	 */
 	public function test($isPersonal = true) {
 		if ($isPersonal) {
 			if ($this->stat('')) {

config/config.sample.php

@@ -831,4 +831,10 @@
 	"style-src 'self' 'unsafe-inline'; frame-src *; img-src *; ".
 	"font-src 'self' data:; media-src *",
 
+/**
+ * Secret used by ownCloud for various purposes, e.g. to encrypt data. If you
+ * lose this string there will be data corruption.
+ */
+'secret' => 'ICertainlyShouldHaveChangedTheDefaultSecret',
+
 );

lib/private/repair.php

@@ -10,6 +10,7 @@
 
 use OC\Hooks\BasicEmitter;
 use OC\Hooks\Emitter;
+use OC\Repair\RepairConfig;
 
 class Repair extends BasicEmitter {
 	/**
@@ -69,7 +70,8 @@ public function addStep($repairStep) {
 	 */
 	public static function getRepairSteps() {
 		return array(
-			new \OC\Repair\RepairMimeTypes()
+			new \OC\Repair\RepairMimeTypes(),
+			new RepairConfig(),
 		);
 	}
 

lib/private/security/crypto.php

@@ -0,0 +1,130 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <[email protected]>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+
+namespace OC\Security;
+
+use Crypt_AES;
+use Crypt_Hash;
+use OCP\Security\ICrypto;
+use OCP\Security\StringUtils;
+use OCP\IConfig;
+
+/**
+ * Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided
+ * it will use the secret defined in config.php as key. Additionally the message will be HMAC'd.
+ *
+ * Usage:
+ * $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText');
+ * $encryptWithCustompassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password');
+ *
+ * @package OC\Security
+ */
+class Crypto implements ICrypto {
+	/** @var Crypt_AES $cipher */
+	private $cipher;
+	/** @var int */
+	private $ivLength = 16;
+	/** @var IConfig */
+	private $config;
+
+	/**
+	 * @param IConfig $config
+	 */
+	function __construct(IConfig $config) {
+		$this->cipher = new Crypt_AES();
+		$this->config = $config;
+	}
+
+	/**
+	 * Custom implementation of hex2bin since the function is only available starting
+	 * with PHP 5.4
+	 *
+	 * @TODO Remove this once 5.3 support for ownCloud is dropped
+	 * @param $message
+	 * @return string
+	 */
+	protected static function hexToBin($message) {
+		if (function_exists('hex2bin')) {
+			return hex2bin($message);
+		}
+
+		return pack("H*", $message);
+	}
+
+	/**
+	 * @param string $message The message to authenticate
+	 * @param string $password Password to use (defaults to `secret` in config.php)
+	 * @return string Calculated HMAC
+	 */
+	public function calculateHMAC($message, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+
+		// Append an "a" behind the password and hash it to prevent reusing the same password as for encryption
+		$password = hash('sha512', $password . 'a');
+
+		$hash = new Crypt_Hash('sha512');
+		$hash->setKey($password);
+		return $hash->hash($message);
+	}
+
+	/**
+	 * Encrypts a value and adds an HMAC (Encrypt-Then-MAC)
+	 * @param string $plaintext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string Authenticated ciphertext
+	 */
+	public function encrypt($plaintext, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+		$this->cipher->setPassword($password);
+
+		$iv = \OC_Util::generateRandomBytes($this->ivLength);
+		$this->cipher->setIV($iv);
+
+		$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
+		$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, $password));
+
+		return $ciphertext.'|'.$iv.'|'.$hmac;
+	}
+
+	/**
+	 * Decrypts a value and verifies the HMAC (Encrypt-Then-Mac)
+	 * @param string $authenticatedCiphertext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string plaintext
+	 * @throws \Exception If the HMAC does not match
+	 */
+	public function decrypt($authenticatedCiphertext, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+		$this->cipher->setPassword($password);
+
+		$parts = explode('|', $authenticatedCiphertext);
+		if(sizeof($parts) !== 3) {
+			throw new \Exception('Authenticated ciphertext could not be decoded.');
+		}
+
+		$ciphertext = self::hexToBin($parts[0]);
+		$iv = $parts[1];
+		$hmac = self::hexToBin($parts[2]);
+
+		$this->cipher->setIV($iv);
+
+		if(!StringUtils::equals($this->calculateHMAC($parts[0].$parts[1], $password), $hmac)) {
+			throw new \Exception('HMAC does not match.');
+		}
+
+		return $this->cipher->decrypt($ciphertext);
+	}
+
+}

lib/private/security/stringutils.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <[email protected]>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OC\Security;
+
+class StringUtils {
+
+	/**
+	 * Compares whether two strings are equal. To prevent guessing of the string
+	 * length this is done by comparing two hashes against each other and afterwards
+	 * a comparison of the real string to prevent against the unlikely chance of
+	 * collisions.
+	 *
+	 * Be aware that this function may leak whether the string to compare have a different
+	 * length.
+	 *
+	 * @param string $expected The expected value
+	 * @param string $input The input to compare against
+	 * @return bool True if the two strings are equal, otherwise false.
+	 */
+	public static function equals($expected, $input) {
+
+		if(!is_string($expected) || !is_string($input)) {
+			return false;
+		}
+
+		if(function_exists('hash_equals')) {
+			return hash_equals($expected, $input);
+		}
+
+		$randomString = \OC_Util::generateRandomBytes(10);
+
+		if(hash('sha512', $expected.$randomString) === hash('sha512', $input.$randomString)) {
+			if($expected === $input) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+}

lib/private/server.php

@@ -10,6 +10,7 @@
 use OC\Files\Node\Root;
 use OC\Files\View;
 use OCP\IServerContainer;
+use OC\Security\Crypto;
 
 /**
  * Class Server
@@ -199,6 +200,9 @@ function __construct() {
 		$this->registerService('Search', function ($c) {
 			return new Search();
 		});
+		$this->registerService('Crypto', function ($c) {
+			return new Crypto(\OC::$server->getConfig());
+		});
 		$this->registerService('Db', function ($c) {
 			return new Db();
 		});
@@ -479,6 +483,15 @@ function getSearch() {
 		return $this->query('Search');
 	}
 
+	/**
+	 * Returns a Crypto instance
+	 *
+	 * @return \OCP\Security\ICrypto
+	 */
+	function getCrypto() {
+		return $this->query('Crypto');
+	}
+
 	/**
 	 * Returns an instance of the db facade
 	 *

lib/private/setup.php

@@ -179,6 +179,7 @@ public static function install($options) {
 		//generate a random salt that is used to salt the local user passwords
 		$salt = OC_Util::generateRandomBytes(30);
 		OC_Config::setValue('passwordsalt', $salt);
+		OC_Config::setValue('secret', OC_Util::generateRandomBytes(96));
 
 		//write the config file
 		OC_Config::setValue('trusted_domains', $trustedDomains);

lib/public/security/icrypto.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <[email protected]>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OCP\Security;
+
+/**
+ * Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided
+ * it will use the secret defined in config.php as key. Additionally the message will be HMAC'd.
+ *
+ * Usage:
+ * $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText');
+ * $encryptWithCustomPassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password');
+ *
+ * @package OCP\Security
+ */
+interface ICrypto {
+
+	/**
+	 * @param string $message The message to authenticate
+	 * @param string $password Password to use (defaults to `secret` in config.php)
+	 * @return string Calculated HMAC
+	 */
+	public function calculateHMAC($message, $password = '');
+
+	/**
+	 * Encrypts a value and adds an HMAC (Encrypt-Then-MAC)
+	 * @param string $plaintext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string Authenticated ciphertext
+	 */
+	public function encrypt($plaintext, $password = '');
+
+	/**
+	 * Decrypts a value and verifies the HMAC (Encrypt-Then-Mac)
+	 * @param string $authenticatedCiphertext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string plaintext
+	 * @throws \Exception If the HMAC does not match
+	 */
+	public function decrypt($authenticatedCiphertext, $password = '');
+}

lib/public/security/stringutils.php

@@ -0,0 +1,25 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <[email protected]>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+
+namespace OCP\Security;
+
+class StringUtils {
+	/**
+	 * Compares whether two strings are equal. To prevent guessing of the string
+	 * length this is done by comparing two hashes against each other and afterwards
+	 * a comparison of the real string to prevent against the unlikely chance of
+	 * collisions.
+	 * @param string $expected The expected value
+	 * @param string $input The input to compare against
+	 * @return bool True if the two strings are equal, otherwise false.
+	 */
+	public static function equals($expected, $input) {
+		return \OC\Security\StringUtils::equals($expected, $input);
+	}
+}