includes/auth/Throttler.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  * @ingroup Auth
  20  */
  21
  22 namespace MediaWiki\Auth;
  23
  24 use BagOStuff;
  25 use MediaWiki\Logger\LoggerFactory;
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Psr\Log\LogLevel;
  29
  30 /**
  31  * A helper class for throttling authentication attempts.
  32  * @package MediaWiki\Auth
  33  * @ingroup Auth
  34  * @since 1.27
  35  */
  36 class Throttler implements LoggerAwareInterface {
  37         /** @var string */
  38         protected $type;
  39         /**
  40          * See documentation of $wgPasswordAttemptThrottle for format. Old (pre-1.27) format is not
  41          * allowed here.
  42          * @var array
  43          * @see https://www.mediawiki.org/wiki/Manual:$wgPasswordAttemptThrottle
  44          */
  45         protected $conditions;
  46         /** @var BagOStuff */
  47         protected $cache;
  48         /** @var LoggerInterface */
  49         protected $logger;
  50         /** @var int|float */
  51         protected $warningLimit;
  52
  53         /**
  54          * @param array $conditions An array of arrays describing throttling conditions.
  55          *     Defaults to $wgPasswordAttemptThrottle. See documentation of that variable for format.
  56          * @param array $params Parameters (all optional):
  57          *   - type: throttle type, used as a namespace for counters,
  58          *   - cache: a BagOStuff object where throttle counters are stored.
  59          *   - warningLimit: the log level will be raised to warning when rejecting an attempt after
  60          *     no less than this many failures.
  61          */
  62         public function __construct( array $conditions = null, array $params = [] ) {
  63                 $invalidParams = array_diff_key( $params,
  64                         array_fill_keys( [ 'type', 'cache', 'warningLimit' ], true ) );
  65                 if ( $invalidParams ) {
  66                         throw new \InvalidArgumentException( 'unrecognized parameters: '
  67                                 . implode( ', ', array_keys( $invalidParams ) ) );
  68                 }
  69
  70                 if ( $conditions === null ) {
  71                         $config = \ConfigFactory::getDefaultInstance()->makeConfig( 'main' );
  72                         $conditions = $config->get( 'PasswordAttemptThrottle' );
  73                         $params += [
  74                                 'type' => 'password',
  75                                 'cache' => \ObjectCache::getLocalClusterInstance(),
  76                                 'warningLimit' => 50,
  77                         ];
  78                 } else {
  79                         $params += [
  80                                 'type' => 'custom',
  81                                 'cache' => \ObjectCache::getLocalClusterInstance(),
  82                                 'warningLimit' => INF,
  83                         ];
  84                 }
  85
  86                 $this->type = $params['type'];
  87                 $this->conditions = static::normalizeThrottleConditions( $conditions );
  88                 $this->cache = $params['cache'];
  89                 $this->warningLimit = $params['warningLimit'];
  90
  91                 $this->setLogger( LoggerFactory::getInstance( 'throttler' ) );
  92         }
  93
  94         public function setLogger( LoggerInterface $logger ) {
  95                 $this->logger = $logger;
  96         }
  97
  98         /**
  99          * Increase the throttle counter and return whether the attempt should be throttled.
 100          *
 101          * Should be called before an authentication attempt.
 102          *
 103          * @param string|null $username
 104          * @param string|null $ip
 105          * @param string|null $caller The authentication method from which we were called.
 106          * @return array|false False if the attempt should not be throttled, an associative array
 107          *   with three keys otherwise:
 108          *   - throttleIndex: which throttle condition was met (a key of the conditions array)
 109          *   - count: throttle count (ie. number of failed attempts)
 110          *   - wait: time in seconds until authentication can be attempted
 111          */
 112         public function increase( $username = null, $ip = null, $caller = null ) {
 113                 if ( $username === null && $ip === null ) {
 114                         throw new \InvalidArgumentException( 'Either username or IP must be set for throttling' );
 115                 }
 116
 117                 $userKey = $username ? md5( $username ) : null;
 118                 foreach ( $this->conditions as $index => $throttleCondition ) {
 119                         $ipKey = isset( $throttleCondition['allIPs'] ) ? null : $ip;
 120                         $count = $throttleCondition['count'];
 121                         $expiry = $throttleCondition['seconds'];
 122
 123                         // a limit of 0 is used as a disable flag in some throttling configuration settings
 124                         // throttling the whole world is probably a bad idea
 125                         if ( !$count || $userKey === null && $ipKey === null ) {
 126                                 continue;
 127                         }
 128
 129                         $throttleKey = wfGlobalCacheKey( 'throttler', $this->type, $index, $ipKey, $userKey );
 130                         $throttleCount = $this->cache->get( $throttleKey );
 131
 132                         if ( !$throttleCount ) {  // counter not started yet
 133                                 $this->cache->add( $throttleKey, 1, $expiry );
 134                         } elseif ( $throttleCount < $count ) { // throttle limited not yet reached
 135                                 $this->cache->incr( $throttleKey );
 136                         } else { // throttled
 137                                 $this->logRejection( [
 138                                         'type' => $this->type,
 139                                         'index' => $index,
 140                                         'ip' => $ipKey,
 141                                         'username' => $username,
 142                                         'count' => $count,
 143                                         'expiry' => $expiry,
 144                                         // @codeCoverageIgnoreStart
 145                                         'method' => $caller ?: __METHOD__,
 146                                         // @codeCoverageIgnoreEnd
 147                                 ] );
 148
 149                                 return [
 150                                         'throttleIndex' => $index,
 151                                         'count' => $count,
 152                                         'wait' => $expiry,
 153                                 ];
 154                         }
 155                 }
 156                 return false;
 157         }
 158
 159         /**
 160          * Clear the throttle counter.
 161          *
 162          * Should be called after a successful authentication attempt.
 163          *
 164          * @param string|null $username
 165          * @param string|null $ip
 166          * @throws \MWException
 167          */
 168         public function clear( $username = null, $ip = null ) {
 169                 $userKey = $username ? md5( $username ) : null;
 170                 foreach ( $this->conditions as $index => $specificThrottle ) {
 171                         $ipKey = isset( $specificThrottle['allIPs'] ) ? null : $ip;
 172                         $throttleKey = wfGlobalCacheKey( 'throttler', $this->type, $index, $ipKey, $userKey );
 173                         $this->cache->delete( $throttleKey );
 174                 }
 175         }
 176
 177         /**
 178          * Handles B/C for $wgPasswordAttemptThrottle.
 179          * @param array $throttleConditions
 180          * @return array
 181          * @see $wgPasswordAttemptThrottle for structure
 182          */
 183         protected static function normalizeThrottleConditions( $throttleConditions ) {
 184                 if ( !is_array( $throttleConditions ) ) {
 185                         return [];
 186                 }
 187                 if ( isset( $throttleConditions['count'] ) ) { // old style
 188                         $throttleConditions = [ $throttleConditions ];
 189                 }
 190                 return $throttleConditions;
 191         }
 192
 193         protected function logRejection( array $context ) {
 194                 $logMsg = 'Throttle {type} hit, throttled for {expiry} seconds due to {count} attempts '
 195                         . 'from username {username} and IP {ip}';
 196
 197                 // If we are hitting a throttle for >= warningLimit attempts, it is much more likely to be
 198                 // an attack than someone simply forgetting their password, so log it at a higher level.
 199                 $level = $context['count'] >= $this->warningLimit ? LogLevel::WARNING : LogLevel::INFO;
 200
 201                 // It should be noted that once the throttle is hit, every attempt to login will
 202                 // generate the log message until the throttle expires, not just the attempt that
 203                 // puts the throttle over the top.
 204                 $this->logger->log( $level, $logMsg, $context );
 205         }
 206
 207 }