From e9f462f0a34e2a07edad2d9783ffb466ce70b927 Mon Sep 17 00:00:00 2001 From: Michael Date: Sat, 12 Sep 2020 12:12:55 +0000 Subject: [PATCH] AP: Improved checks for incoming posts --- src/Protocol/ActivityPub/Receiver.php | 108 +++++++++++++++++++------- 1 file changed, 80 insertions(+), 28 deletions(-) diff --git a/src/Protocol/ActivityPub/Receiver.php b/src/Protocol/ActivityPub/Receiver.php index c7d3ac6757..8a3f76c5ea 100644 --- a/src/Protocol/ActivityPub/Receiver.php +++ b/src/Protocol/ActivityPub/Receiver.php @@ -33,7 +33,6 @@ use Friendica\Model\Item; use Friendica\Model\User; use Friendica\Protocol\Activity; use Friendica\Protocol\ActivityPub; -use Friendica\Util\DateTimeFormat; use Friendica\Util\HTTPSignature; use Friendica\Util\JsonLD; use Friendica\Util\LDSignature; @@ -59,6 +58,12 @@ class Receiver const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio']; const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept']; + const TARGET_UNKNOWN = 0; + const TARGET_TO = 1; + const TARGET_CC = 2; + const TARGET_BCC = 3; + const TARGET_FOLLOWER = 4; + /** * Checks if the web request is done for the AP protocol * @@ -88,6 +93,7 @@ class Receiver Logger::info('Valid HTTP signature', ['signer' => $http_signer]); } + $signer = [$http_signer]; $activity = json_decode($body, true); if (empty($activity)) { @@ -105,6 +111,8 @@ class Receiver $ld_signer = LDSignature::getSigner($activity); if (empty($ld_signer)) { Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG); + } elseif ($ld_signer != $http_signer) { + $signer[] = $ld_signer; } if (!empty($ld_signer && ($actor == $http_signer))) { Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG); @@ -127,7 +135,7 @@ class Receiver $trust_source = false; } - self::processActivity($ldactivity, $body, $uid, $trust_source, true); + self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer); } /** @@ -186,9 +194,27 @@ class Receiver */ public static function prepareObjectData($activity, $uid, $push, &$trust_source) { + $id = JsonLD::fetchElement($activity, '@id'); + if (!empty($id) && !$trust_source) { + $fetched_activity = ActivityPub::fetchContent($id, $uid ?? 0); + if (!empty($fetched_activity)) { + $object = JsonLD::compact($fetched_activity); + $fetched_id = JsonLD::fetchElement($object, '@id'); + if ($fetched_id == $id) { + Logger::info('Activity had been fetched successfully', ['id' => $id]); + $trust_source = true; + $activity = $object; + } else { + Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]); + } + } else { + Logger::info('Activity could not been fetched', ['id' => $id]); + } + } + $actor = JsonLD::fetchElement($activity, 'as:actor', '@id'); if (empty($actor)) { - Logger::log('Empty actor', Logger::DEBUG); + Logger::info('Empty actor', ['activity' => $activity]); return []; } @@ -196,9 +222,11 @@ class Receiver // Fetch all receivers from to, cc, bto and bcc $receivers = self::getReceivers($activity, $actor); + $reception_type = []; // When it is a delivery to a personal inbox we add that user to the receivers if (!empty($uid)) { + $reception_type[$uid] = self::TARGET_BCC; $additional = ['uid:' . $uid => $uid]; $receivers = array_merge($receivers, $additional); } else { @@ -222,11 +250,8 @@ class Receiver // Fetch the content only on activities where this matters if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) { - if ($type == 'as:Announce') { - $trust_source = false; - } - - $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid); + // Always fetch on "Announce" + $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $uid); if (empty($object_data)) { Logger::log("Object data couldn't be processed", Logger::DEBUG); return []; @@ -246,9 +271,6 @@ class Receiver } else { $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage'); } - - // We had been able to retrieve the object data - so we can trust the source - $trust_source = true; } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) { // Create a mostly empty array out of the activity data (instead of the object). // This way we later don't have to check for the existence of ech individual array element. @@ -288,6 +310,19 @@ class Receiver $object_data['actor'] = $actor; $object_data['item_receiver'] = $receivers; $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers); + $object_data['reception_type'] = $reception_type; + + $author = $object_data['author'] ?? $actor; + if (!empty($author) && !empty($object_data['id'])) { + $author_host = parse_url($author, PHP_URL_HOST); + $id_host = parse_url($object_data['id'], PHP_URL_HOST); + if ($author_host == $id_host) { + Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]); + } else { + Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]); + $trust_source = false; + } + } Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG); @@ -320,43 +355,49 @@ class Receiver * @param boolean $push Message had been pushed to our system * @throws \Exception */ - public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false) + public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = []) { $type = JsonLD::fetchElement($activity, '@type'); if (!$type) { - Logger::log('Empty type', Logger::DEBUG); + Logger::info('Empty type', ['activity' => $activity]); return; } if (!JsonLD::fetchElement($activity, 'as:object', '@id')) { - Logger::log('Empty object', Logger::DEBUG); + Logger::info('Empty object', ['activity' => $activity]); return; } - if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) { - Logger::log('Empty actor', Logger::DEBUG); + $actor = JsonLD::fetchElement($activity, 'as:actor', '@id'); + if (empty($actor)) { + Logger::info('Empty actor', ['activity' => $activity]); return; } - // Don't trust the source if "actor" differs from "attributedTo". The content could be forged. - if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) { - $actor = JsonLD::fetchElement($activity, 'as:actor', '@id'); + if (is_array($activity['as:object'])) { $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id'); - $trust_source = ($actor == $attributed_to); - if (!$trust_source) { - Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG); + } else { + $attributed_to = ''; + } + + // Test the provided signatures against the actor and "attributedTo" + if ($trust_source) { + if (!empty($attributed_to) && !empty($actor)) { + $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer)); + } else { + $trust_source = in_array($actor, $signer); } } // $trust_source is called by reference and is set to true if the content was retrieved successfully $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source); if (empty($object_data)) { - Logger::log('No object data found', Logger::DEBUG); + Logger::info('No object data found', ['activity' => $activity]); return; } if (!$trust_source) { - Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG); + Logger::info('Activity trust could not be achieved.', ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]); return; } @@ -517,7 +558,7 @@ class Receiver Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG); } else { - Logger::log('Empty actor', Logger::DEBUG); + Logger::info('Empty actor', ['activity' => $activity]); $followers = ''; } @@ -775,18 +816,29 @@ class Receiver $data = ActivityPub\Transmitter::createNote($item); $object = JsonLD::compact($data); } + + $id = JsonLD::fetchElement($object, '@id'); + if (empty($id)) { + Logger::info('Empty id'); + return false; + } + + if ($id != $object_id) { + Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]); + return false; + } } else { Logger::log('Using original object for url ' . $object_id, Logger::DEBUG); } $type = JsonLD::fetchElement($object, '@type'); - if (empty($type)) { - Logger::log('Empty type', Logger::DEBUG); + Logger::info('Empty type'); return false; } - if (in_array($type, self::CONTENT_TYPES)) { + // We currently don't handle 'pt:CacheFile', but with this step we avoid logging + if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) { $object_data = self::processObject($object); if (!empty($data)) {