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<?php
/**
* @copyright Copyright (c) 2016 Lukas Reschke <lukas@statuscode.ch>
*
* @author Bjoern Schiessle <bjoern@schiessle.org>
* @author Lukas Reschke <lukas@statuscode.ch>
* @author Robin Appelman <robin@icewind.nl>
* @author Roeland Jago Douma <roeland@famdouma.nl>
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* 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
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
namespace OC\Security\Bruteforce;
use OC\Security\Normalizer\IpAddress;
use OCP\AppFramework\Utility\ITimeFactory;
use OCP\IConfig;
use OCP\IDBConnection;
use OCP\ILogger;
/**
* Class Throttler implements the bruteforce protection for security actions in
* Nextcloud.
*
* It is working by logging invalid login attempts to the database and slowing
* down all login attempts from the same subnet. The max delay is 30 seconds and
* the starting delay are 200 milliseconds. (after the first failed login)
*
* This is based on Paragonie's AirBrake for Airship CMS. You can find the original
* code at https://github.com/paragonie/airship/blob/7e5bad7e3c0fbbf324c11f963fd1f80e59762606/src/Engine/Security/AirBrake.php
*
* @package OC\Security\Bruteforce
*/
class Throttler {
const LOGIN_ACTION = 'login';
/** @var IDBConnection */
private $db;
/** @var ITimeFactory */
private $timeFactory;
/** @var ILogger */
private $logger;
/** @var IConfig */
private $config;
/**
* @param IDBConnection $db
* @param ITimeFactory $timeFactory
* @param ILogger $logger
* @param IConfig $config
*/
public function __construct(IDBConnection $db,
ITimeFactory $timeFactory,
ILogger $logger,
IConfig $config) {
$this->db = $db;
$this->timeFactory = $timeFactory;
$this->logger = $logger;
$this->config = $config;
}
/**
* Convert a number of seconds into the appropriate DateInterval
*
* @param int $expire
* @return \DateInterval
*/
private function getCutoff($expire) {
$d1 = new \DateTime();
$d2 = clone $d1;
$d2->sub(new \DateInterval('PT' . $expire . 'S'));
return $d2->diff($d1);
}
/**
* Register a failed attempt to bruteforce a security control
*
* @param string $action
* @param string $ip
* @param array $metadata Optional metadata logged to the database
* @suppress SqlInjectionChecker
*/
public function registerAttempt($action,
$ip,
array $metadata = []) {
// No need to log if the bruteforce protection is disabled
if($this->config->getSystemValue('auth.bruteforce.protection.enabled', true) === false) {
return;
}
$ipAddress = new IpAddress($ip);
$values = [
'action' => $action,
'occurred' => $this->timeFactory->getTime(),
'ip' => (string)$ipAddress,
'subnet' => $ipAddress->getSubnet(),
'metadata' => json_encode($metadata),
];
$this->logger->notice(
sprintf(
'Bruteforce attempt from "%s" detected for action "%s".',
$ip,
$action
),
[
'app' => 'core',
]
);
$qb = $this->db->getQueryBuilder();
$qb->insert('bruteforce_attempts');
foreach($values as $column => $value) {
$qb->setValue($column, $qb->createNamedParameter($value));
}
$qb->execute();
}
/**
* Check if the IP is whitelisted
*
* @param string $ip
* @return bool
*/
private function isIPWhitelisted($ip) {
if($this->config->getSystemValue('auth.bruteforce.protection.enabled', true) === false) {
return true;
}
$keys = $this->config->getAppKeys('bruteForce');
$keys = array_filter($keys, function($key) {
$regex = '/^whitelist_/S';
return preg_match($regex, $key) === 1;
});
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
$type = 4;
} else if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
$type = 6;
} else {
return false;
}
$ip = inet_pton($ip);
foreach ($keys as $key) {
$cidr = $this->config->getAppValue('bruteForce', $key, null);
$cx = explode('/', $cidr);
$addr = $cx[0];
$mask = (int)$cx[1];
// Do not compare ipv4 to ipv6
if (($type === 4 && !filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) ||
($type === 6 && !filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6))) {
continue;
}
$addr = inet_pton($addr);
$valid = true;
for($i = 0; $i < $mask; $i++) {
$part = ord($addr[(int)($i/8)]);
$orig = ord($ip[(int)($i/8)]);
$part = $part & (15 << (1 - ($i % 2)));
$orig = $orig & (15 << (1 - ($i % 2)));
if ($part !== $orig) {
$valid = false;
break;
}
}
if ($valid === true) {
return true;
}
}
return false;
}
/**
* Get the throttling delay (in milliseconds)
*
* @param string $ip
* @param string $action optionally filter by action
* @return int
*/
public function getDelay($ip, $action = '') {
$ipAddress = new IpAddress($ip);
if ($this->isIPWhitelisted((string)$ipAddress)) {
return 0;
}
$cutoffTime = (new \DateTime())
->sub($this->getCutoff(43200))
->getTimestamp();
$qb = $this->db->getQueryBuilder();
$qb->select('*')
->from('bruteforce_attempts')
->where($qb->expr()->gt('occurred', $qb->createNamedParameter($cutoffTime)))
->andWhere($qb->expr()->eq('subnet', $qb->createNamedParameter($ipAddress->getSubnet())));
if ($action !== '') {
$qb->andWhere($qb->expr()->eq('action', $qb->createNamedParameter($action)));
}
$attempts = count($qb->execute()->fetchAll());
if ($attempts === 0) {
return 0;
}
$maxDelay = 30;
$firstDelay = 0.1;
if ($attempts > (8 * PHP_INT_SIZE - 1)) {
// Don't ever overflow. Just assume the maxDelay time:s
$firstDelay = $maxDelay;
} else {
$firstDelay *= pow(2, $attempts);
if ($firstDelay > $maxDelay) {
$firstDelay = $maxDelay;
}
}
return (int) \ceil($firstDelay * 1000);
}
/**
* Reset the throttling delay for an IP address, action and metadata
*
* @param string $ip
* @param string $action
* @param string $metadata
*/
public function resetDelay($ip, $action, $metadata) {
$ipAddress = new IpAddress($ip);
if ($this->isIPWhitelisted((string)$ipAddress)) {
return;
}
$cutoffTime = (new \DateTime())
->sub($this->getCutoff(43200))
->getTimestamp();
$qb = $this->db->getQueryBuilder();
$qb->delete('bruteforce_attempts')
->where($qb->expr()->gt('occurred', $qb->createNamedParameter($cutoffTime)))
->andWhere($qb->expr()->eq('subnet', $qb->createNamedParameter($ipAddress->getSubnet())))
->andWhere($qb->expr()->eq('action', $qb->createNamedParameter($action)))
->andWhere($qb->expr()->eq('metadata', $qb->createNamedParameter(json_encode($metadata))));
$qb->execute();
}
/**
* Will sleep for the defined amount of time
*
* @param string $ip
* @param string $action optionally filter by action
* @return int the time spent sleeping
*/
public function sleepDelay($ip, $action = '') {
$delay = $this->getDelay($ip, $action);
usleep($delay * 1000);
return $delay;
}
}