From patchwork Mon Mar 10 21:25:24 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Linus_L=C3=BCssing?= X-Patchwork-Id: 328850 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 1E8E42C00D3 for ; Tue, 11 Mar 2014 08:26:55 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754444AbaCJV0S (ORCPT ); Mon, 10 Mar 2014 17:26:18 -0400 Received: from mout.web.de ([212.227.15.14]:53159 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753951AbaCJV0Q (ORCPT ); Mon, 10 Mar 2014 17:26:16 -0400 Received: from localhost ([95.211.10.3]) by smtp.web.de (mrweb101) with ESMTPSA (Nemesis) id 0LbrQm-1X47QS0EYm-00jGDB; Mon, 10 Mar 2014 22:26:09 +0100 From: =?UTF-8?q?Linus=20L=C3=BCssing?= To: netdev@vger.kernel.org Cc: bridge@lists.linux-foundation.org, Stephen Hemminger , "David S. Miller" , linux-kernel@vger.kernel.org, Jan Stancek , Florian Westphal , =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCHv2 1/2] bridge: multicast: add sanity check for general query destination Date: Mon, 10 Mar 2014 22:25:24 +0100 Message-Id: <1394486725-4992-1-git-send-email-linus.luessing@web.de> X-Mailer: git-send-email 1.9.0 MIME-Version: 1.0 X-Provags-ID: V03:K0:mBt8yo0zDR/yERTqkgyYGJb2+KmS9p2eL3wkXQ2x0yi87RPUrrB RpZP5JG6WYzPf7eYTEIKXuNoZ5bgusLj/85KyjnNLuatW2JKPzoZAcTRePs6ImkZ/dj1sUp 138qW/5cAZxHL0rJ2UkqNcWEgyyx3fSMPCDpRJdJLJGFL251My+kGynw4oeO1OYY8zbKkE7 oZLCUbAQjYnkk/rapdEpQ== Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org General IGMP and MLD queries are supposed to have the multicast link-local all-nodes address as their destination according to RFC2236 section 9, RFC3376 section 4.1.12/9.1, RFC2710 section 8 and RFC3810 section 5.1.15. Without this check, such malformed IGMP/MLD queries can result in a denial of service: The queries are ignored by most IGMP/MLD listeners therefore they will not respond with an IGMP/MLD report. However, without this patch these malformed MLD queries would enable the snooping part in the bridge code, potentially shutting down the according ports towards these hosts for multicast traffic as the bridge did not learn about these listeners. Reported-by: Jan Stancek Signed-off-by: Linus Lüssing --- v2: simplified is_general_query variable assignment (thanks Cong!) net/bridge/br_multicast.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index fb0e36f..e56bae4 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1181,6 +1181,14 @@ static int br_ip4_multicast_query(struct net_bridge *br, IGMPV3_MRC(ih3->code) * (HZ / IGMP_TIMER_SCALE) : 1; } + /* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer + * all-systems destination addresses (224.0.0.1) for general queries + */ + if (!group && iph->daddr != htonl(INADDR_ALLHOSTS_GROUP)) { + err = -EINVAL; + goto out; + } + br_multicast_query_received(br, port, &br->ip4_querier, !!iph->saddr, max_delay); @@ -1228,6 +1236,7 @@ static int br_ip6_multicast_query(struct net_bridge *br, unsigned long max_delay; unsigned long now = jiffies; const struct in6_addr *group = NULL; + bool is_general_query; int err = 0; spin_lock(&br->multicast_lock); @@ -1262,6 +1271,16 @@ static int br_ip6_multicast_query(struct net_bridge *br, max_delay = max(msecs_to_jiffies(mldv2_mrc(mld2q)), 1UL); } + is_general_query = group && ipv6_addr_any(group); + + /* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer + * all-nodes destination address (ff02::1) for general queries + */ + if (is_general_query && !ipv6_addr_is_ll_all_nodes(&ip6h->daddr)) { + err = -EINVAL; + goto out; + } + br_multicast_query_received(br, port, &br->ip6_querier, !ipv6_addr_any(&ip6h->saddr), max_delay);