Add AuthManager

This implements the AuthManager class and its needed interfaces and
subclasses, and integrates them into the backend portion of MediaWiki.
Integration with frontend portions of MediaWiki (e.g. ApiLogin,
Special:Login) is left for a followup.

Bug: T91699
Bug: T71589
Bug: T111299
Co-Authored-By: Gergő Tisza <gtisza@wikimedia.org>
Change-Id: If89d24838e326fe25fe867d02181eebcfbb0e196

1 files changed, 210 insertions, 0 deletions

diff --git a/includes/auth/Throttler.php b/includes/auth/Throttler.php
new file mode 100644
index 000000000000..5b14a3baffb7
--- /dev/null
+++ b/includes/auth/Throttler.php
@@ -0,0 +1,210 @@
+<?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 Config;
+use MediaWiki\Logger\LoggerFactory;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LogLevel;
+use Psr\Log\NullLogger;
+use User;
+
+/**
+ * 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 = \ConfigFactory::getDefaultInstance()->makeConfig( 'main' );
+			$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( [
+					'type' => $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 {type} 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 );
+	}
+
+}