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<?php
declare(strict_types=1);
/**
* @copyright Copyright (c) 2016 Lukas Reschke <lukas@statuscode.ch>
*
* @author Bjoern Schiessle <bjoern@schiessle.org>
* @author Christoph Wurst <christoph@winzerhof-wurst.at>
* @author Joas Schilling <coding@schilljs.com>
* @author Johannes Riedel <joeried@users.noreply.github.com>
* @author Lukas Reschke <lukas@statuscode.ch>
* @author Morris Jobke <hey@morrisjobke.de>
* @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;
use OCP\Security\Bruteforce\MaxDelayReached;
/**
* 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 {
public const LOGIN_ACTION = 'login';
public const MAX_DELAY = 25;
public const MAX_DELAY_MS = 25000; // in milliseconds
public const MAX_ATTEMPTS = 10;
/** @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(int $expire): \DateInterval {
$d1 = new \DateTime();
$d2 = clone $d1;
$d2->sub(new \DateInterval('PT' . $expire . 'S'));
return $d2->diff($d1);
}
/**
* Calculate the cut off timestamp
*
* @param float $maxAgeHours
* @return int
*/
private function getCutoffTimestamp(float $maxAgeHours = 12.0): int {
return (new \DateTime())
->sub($this->getCutoff((int) ($maxAgeHours * 3600)))
->getTimestamp();
}
/**
* Register a failed attempt to bruteforce a security control
*
* @param string $action
* @param string $ip
* @param array $metadata Optional metadata logged to the database
*/
public function registerAttempt(string $action,
string $ip,
array $metadata = []): void {
// No need to log if the bruteforce protection is disabled
if ($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(string $ip): bool {
if ($this->config->getSystemValue('auth.bruteforce.protection.enabled', true) === false) {
return true;
}
$keys = $this->config->getAppKeys('bruteForce');
$keys = array_filter($keys, function ($key) {
return 0 === strpos($key, 'whitelist_');
});
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
$type = 4;
} elseif (filter_var($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)]);
$bitmask = 1 << (7 - ($i % 8));
$part = $part & $bitmask;
$orig = $orig & $bitmask;
if ($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
* @param float $maxAgeHours
* @return int
*/
public function getAttempts(string $ip, string $action = '', float $maxAgeHours = 12): int {
if ($ip === '') {
return 0;
}
$ipAddress = new IpAddress($ip);
if ($this->isIPWhitelisted((string)$ipAddress)) {
return 0;
}
$cutoffTime = $this->getCutoffTimestamp($maxAgeHours);
$qb = $this->db->getQueryBuilder();
$qb->select($qb->func()->count('*', 'attempts'))
->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)));
}
$result = $qb->execute();
$row = $result->fetch();
$result->closeCursor();
return (int) $row['attempts'];
}
/**
* Get the throttling delay (in milliseconds)
*
* @param string $ip
* @param string $action optionally filter by action
* @return int
*/
public function getDelay(string $ip, string $action = ''): int {
$attempts = $this->getAttempts($ip, $action);
if ($attempts === 0) {
return 0;
}
$firstDelay = 0.1;
if ($attempts > self::MAX_ATTEMPTS) {
// Don't ever overflow. Just assume the maxDelay time:s
return self::MAX_DELAY_MS;
}
$delay = $firstDelay * 2 ** $attempts;
if ($delay > self::MAX_DELAY) {
return self::MAX_DELAY_MS;
}
return (int) \ceil($delay * 1000);
}
/**
* Reset the throttling delay for an IP address, action and metadata
*
* @param string $ip
* @param string $action
* @param array $metadata
*/
public function resetDelay(string $ip, string $action, array $metadata): void {
$ipAddress = new IpAddress($ip);
if ($this->isIPWhitelisted((string)$ipAddress)) {
return;
}
$cutoffTime = $this->getCutoffTimestamp();
$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();
}
/**
* Reset the throttling delay for an IP address
*
* @param string $ip
*/
public function resetDelayForIP($ip) {
$cutoffTime = $this->getCutoffTimestamp();
$qb = $this->db->getQueryBuilder();
$qb->delete('bruteforce_attempts')
->where($qb->expr()->gt('occurred', $qb->createNamedParameter($cutoffTime)))
->andWhere($qb->expr()->eq('ip', $qb->createNamedParameter($ip)));
$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(string $ip, string $action = ''): int {
$delay = $this->getDelay($ip, $action);
usleep($delay * 1000);
return $delay;
}
/**
* Will sleep for the defined amount of time unless maximum was reached in the last 30 minutes
* In this case a "429 Too Many Request" exception is thrown
*
* @param string $ip
* @param string $action optionally filter by action
* @return int the time spent sleeping
* @throws MaxDelayReached when reached the maximum
*/
public function sleepDelayOrThrowOnMax(string $ip, string $action = ''): int {
$delay = $this->getDelay($ip, $action);
if (($delay === self::MAX_DELAY_MS) && $this->getAttempts($ip, $action, 0.5) > self::MAX_ATTEMPTS) {
// If the ip made too many attempts within the last 30 mins we don't execute anymore
throw new MaxDelayReached('Reached maximum delay');
}
usleep($delay * 1000);
return $delay;
}
}
|