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EmergencyWatcher.php
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EmergencyWatcher.php
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<?php
namespace MediaWiki\Extension\AbuseFilter\Watcher;
use InvalidArgumentException;
use MediaWiki\Config\ServiceOptions;
use MediaWiki\Deferred\AutoCommitUpdate;
use MediaWiki\Deferred\DeferredUpdates;
use MediaWiki\Extension\AbuseFilter\EchoNotifier;
use MediaWiki\Extension\AbuseFilter\EmergencyCache;
use MediaWiki\Extension\AbuseFilter\FilterLookup;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\LBFactory;
/**
* Service for monitoring filters with restricted actions and preventing them
* from executing destructive actions ("throttling")
*
* @todo We should log throttling somewhere
*/
class EmergencyWatcher implements Watcher {
public const SERVICE_NAME = 'AbuseFilterEmergencyWatcher';
public const CONSTRUCTOR_OPTIONS = [
'AbuseFilterEmergencyDisableAge',
'AbuseFilterEmergencyDisableCount',
'AbuseFilterEmergencyDisableThreshold',
];
/** @var EmergencyCache */
private $cache;
/** @var LBFactory */
private $lbFactory;
/** @var FilterLookup */
private $filterLookup;
/** @var EchoNotifier */
private $notifier;
/** @var ServiceOptions */
private $options;
/**
* @param EmergencyCache $cache
* @param LBFactory $lbFactory
* @param FilterLookup $filterLookup
* @param EchoNotifier $notifier
* @param ServiceOptions $options
*/
public function __construct(
EmergencyCache $cache,
LBFactory $lbFactory,
FilterLookup $filterLookup,
EchoNotifier $notifier,
ServiceOptions $options
) {
$options->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS );
$this->cache = $cache;
$this->lbFactory = $lbFactory;
$this->filterLookup = $filterLookup;
$this->notifier = $notifier;
$this->options = $options;
}
/**
* Determine which filters must be throttled, i.e. their potentially dangerous
* actions must be disabled.
*
* @param int[] $filters The filters to check
* @param string $group Group the filters belong to
* @return int[] Array of filters to be throttled
*/
public function getFiltersToThrottle( array $filters, string $group ): array {
$filters = array_intersect(
$filters,
$this->cache->getFiltersToCheckInGroup( $group )
);
if ( $filters === [] ) {
return [];
}
$threshold = $this->getEmergencyValue( 'threshold', $group );
$hitCountLimit = $this->getEmergencyValue( 'count', $group );
$maxAge = $this->getEmergencyValue( 'age', $group );
$time = (int)wfTimestamp( TS_UNIX );
$throttleFilters = [];
foreach ( $filters as $filter ) {
$filterObj = $this->filterLookup->getFilter( $filter, false );
// TODO: consider removing the filter from the group key
// after throttling
if ( $filterObj->isThrottled() ) {
continue;
}
$filterAge = (int)wfTimestamp( TS_UNIX, $filterObj->getTimestamp() );
$exemptTime = $filterAge + $maxAge;
// Optimize for the common case when filters are well-established
// This check somewhat duplicates the role of cache entry's TTL
// and could as well be removed
if ( $exemptTime <= $time ) {
continue;
}
// TODO: this value might be stale, there is no guarantee the match
// has actually been recorded now
$cacheValue = $this->cache->getForFilter( $filter );
if ( $cacheValue === false ) {
continue;
}
[ 'total' => $totalActions, 'matches' => $matchCount ] = $cacheValue;
if ( $matchCount > $hitCountLimit && ( $matchCount / $totalActions ) > $threshold ) {
// More than AbuseFilterEmergencyDisableCount matches, constituting more than
// AbuseFilterEmergencyDisableThreshold (a fraction) of last few edits.
// Disable it.
$throttleFilters[] = $filter;
}
}
return $throttleFilters;
}
/**
* Determine which a filters must be throttled and apply the throttling
*
* @inheritDoc
*/
public function run( array $localFilters, array $globalFilters, string $group ): void {
$throttleFilters = $this->getFiltersToThrottle( $localFilters, $group );
if ( !$throttleFilters ) {
return;
}
DeferredUpdates::addUpdate(
new AutoCommitUpdate(
$this->lbFactory->getPrimaryDatabase(),
__METHOD__,
static function ( IDatabase $dbw, $fname ) use ( $throttleFilters ) {
$dbw->newUpdateQueryBuilder()
->update( 'abuse_filter' )
->set( [ 'af_throttled' => 1 ] )
->where( [ 'af_id' => $throttleFilters ] )
->caller( $fname )
->execute();
}
)
);
DeferredUpdates::addCallableUpdate( function () use ( $throttleFilters ) {
foreach ( $throttleFilters as $filter ) {
$this->notifier->notifyForFilter( $filter );
}
} );
}
/**
* @param string $type The value to get, either "threshold", "count" or "age"
* @param string $group The filter's group (as defined in $wgAbuseFilterValidGroups)
* @return mixed
*/
private function getEmergencyValue( string $type, string $group ) {
switch ( $type ) {
case 'threshold':
$opt = 'AbuseFilterEmergencyDisableThreshold';
break;
case 'count':
$opt = 'AbuseFilterEmergencyDisableCount';
break;
case 'age':
$opt = 'AbuseFilterEmergencyDisableAge';
break;
default:
// @codeCoverageIgnoreStart
throw new InvalidArgumentException( '$type must be either "threshold", "count" or "age"' );
// @codeCoverageIgnoreEnd
}
$value = $this->options->get( $opt );
return $value[$group] ?? $value['default'];
}
}

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Sat, May 16, 11:47 (15 h, 16 m)
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EmergencyWatcher.php (5 KB)

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