Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754499AbaDRJkC (ORCPT ); Fri, 18 Apr 2014 05:40:02 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:45951 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752254AbaDRJWs (ORCPT ); Fri, 18 Apr 2014 05:22:48 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?Linus=20L=C3=BCssing?= , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 40/72] bridge: multicast: add sanity check for general query destination Date: Fri, 18 Apr 2014 11:22:13 +0200 Message-Id: X-Mailer: git-send-email 1.9.2 In-Reply-To: <3389f243c528afc7c7300c83b8f296290cd3656d.1397812482.git.jslaby@suse.cz> References: <3389f243c528afc7c7300c83b8f296290cd3656d.1397812482.git.jslaby@suse.cz> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Lüssing 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ Upstream commit 9ed973cc40c588abeaa58aea0683ea665132d11d ] 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 Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- 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 b98627e902e7..4af88e2a33c4 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1183,6 +1183,14 @@ 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); @@ -1230,6 +1238,7 @@ 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; u16 vid = 0; @@ -1265,6 +1274,16 @@ 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); -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/