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[mediawiki.git] / includes / auth / Throttler.php

<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Auth
 */

namespace MediaWiki\Auth;

use BagOStuff;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\LogLevel;

/**
 * A helper class for throttling authentication attempts.
 * @package MediaWiki\Auth
 * @ingroup Auth
 * @since 1.27
 */
class Throttler implements LoggerAwareInterface {
        /** @var string */
        protected $type;
        /**
         * See documentation of $wgPasswordAttemptThrottle for format. Old (pre-1.27) format is not
         * allowed here.
         * @var array
         * @see https://www.mediawiki.org/wiki/Manual:$wgPasswordAttemptThrottle
         */
        protected $conditions;
        /** @var BagOStuff */
        protected $cache;
        /** @var LoggerInterface */
        protected $logger;
        /** @var int|float */
        protected $warningLimit;

        /**
         * @param array $conditions An array of arrays describing throttling conditions.
         *     Defaults to $wgPasswordAttemptThrottle. See documentation of that variable for format.
         * @param array $params Parameters (all optional):
         *   - type: throttle type, used as a namespace for counters,
         *   - cache: a BagOStuff object where throttle counters are stored.
         *   - warningLimit: the log level will be raised to warning when rejecting an attempt after
         *     no less than this many failures.
         */
        public function __construct( array $conditions = null, array $params = [] ) {
                $invalidParams = array_diff_key( $params,
                        array_fill_keys( [ 'type', 'cache', 'warningLimit' ], true ) );
                if ( $invalidParams ) {
                        throw new \InvalidArgumentException( 'unrecognized parameters: '
                                . implode( ', ', array_keys( $invalidParams ) ) );
                }

                if ( $conditions === null ) {
                        $config = MediaWikiServices::getInstance()->getMainConfig();
                        $conditions = $config->get( 'PasswordAttemptThrottle' );
                        $params += [
                                'type' => 'password',
                                'cache' => \ObjectCache::getLocalClusterInstance(),
                                'warningLimit' => 50,
                        ];
                } else {
                        $params += [
                                'type' => 'custom',
                                'cache' => \ObjectCache::getLocalClusterInstance(),
                                'warningLimit' => INF,
                        ];
                }

                $this->type = $params['type'];
                $this->conditions = static::normalizeThrottleConditions( $conditions );
                $this->cache = $params['cache'];
                $this->warningLimit = $params['warningLimit'];

                $this->setLogger( LoggerFactory::getInstance( 'throttler' ) );
        }

        public function setLogger( LoggerInterface $logger ) {
                $this->logger = $logger;
        }

        /**
         * Increase the throttle counter and return whether the attempt should be throttled.
         *
         * Should be called before an authentication attempt.
         *
         * @param string|null $username
         * @param string|null $ip
         * @param string|null $caller The authentication method from which we were called.
         * @return array|false False if the attempt should not be throttled, an associative array
         *   with three keys otherwise:
         *   - throttleIndex: which throttle condition was met (a key of the conditions array)
         *   - count: throttle count (ie. number of failed attempts)
         *   - wait: time in seconds until authentication can be attempted
         */
        public function increase( $username = null, $ip = null, $caller = null ) {
                if ( $username === null && $ip === null ) {
                        throw new \InvalidArgumentException( 'Either username or IP must be set for throttling' );
                }

                $userKey = $username ? md5( $username ) : null;
                foreach ( $this->conditions as $index => $throttleCondition ) {
                        $ipKey = isset( $throttleCondition['allIPs'] ) ? null : $ip;
                        $count = $throttleCondition['count'];
                        $expiry = $throttleCondition['seconds'];

                        // a limit of 0 is used as a disable flag in some throttling configuration settings
                        // throttling the whole world is probably a bad idea
                        if ( !$count || $userKey === null && $ipKey === null ) {
                                continue;
                        }

                        $throttleKey = wfGlobalCacheKey( 'throttler', $this->type, $index, $ipKey, $userKey );
                        $throttleCount = $this->cache->get( $throttleKey );

                        if ( !$throttleCount ) {  // counter not started yet
                                $this->cache->add( $throttleKey, 1, $expiry );
                        } elseif ( $throttleCount < $count ) { // throttle limited not yet reached
                                $this->cache->incr( $throttleKey );
                        } else { // throttled
                                $this->logRejection( [
                                        'throttle' => $this->type,
                                        'index' => $index,
                                        'ip' => $ipKey,
                                        'username' => $username,
                                        'count' => $count,
                                        'expiry' => $expiry,
                                        // @codeCoverageIgnoreStart
                                        'method' => $caller ?: __METHOD__,
                                        // @codeCoverageIgnoreEnd
                                ] );

                                return [
                                        'throttleIndex' => $index,
                                        'count' => $count,
                                        'wait' => $expiry,
                                ];
                        }
                }
                return false;
        }

        /**
         * Clear the throttle counter.
         *
         * Should be called after a successful authentication attempt.
         *
         * @param string|null $username
         * @param string|null $ip
         * @throws \MWException
         */
        public function clear( $username = null, $ip = null ) {
                $userKey = $username ? md5( $username ) : null;
                foreach ( $this->conditions as $index => $specificThrottle ) {
                        $ipKey = isset( $specificThrottle['allIPs'] ) ? null : $ip;
                        $throttleKey = wfGlobalCacheKey( 'throttler', $this->type, $index, $ipKey, $userKey );
                        $this->cache->delete( $throttleKey );
                }
        }

        /**
         * Handles B/C for $wgPasswordAttemptThrottle.
         * @param array $throttleConditions
         * @return array
         * @see $wgPasswordAttemptThrottle for structure
         */
        protected static function normalizeThrottleConditions( $throttleConditions ) {
                if ( !is_array( $throttleConditions ) ) {
                        return [];
                }
                if ( isset( $throttleConditions['count'] ) ) { // old style
                        $throttleConditions = [ $throttleConditions ];
                }
                return $throttleConditions;
        }

        protected function logRejection( array $context ) {
                $logMsg = 'Throttle {throttle} hit, throttled for {expiry} seconds due to {count} attempts '
                        . 'from username {username} and IP {ip}';

                // If we are hitting a throttle for >= warningLimit attempts, it is much more likely to be
                // an attack than someone simply forgetting their password, so log it at a higher level.
                $level = $context['count'] >= $this->warningLimit ? LogLevel::WARNING : LogLevel::INFO;

                // It should be noted that once the throttle is hit, every attempt to login will
                // generate the log message until the throttle expires, not just the attempt that
                // puts the throttle over the top.
                $this->logger->log( $level, $logMsg, $context );
        }

}