| Message ID | 1394486725-4992-1-git-send-email-linus.luessing@web.de |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Linus Lüssing <linus.luessing@web.de> Date: Mon, 10 Mar 2014 22:25:24 +0100 > 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 <jstancek@redhat.com> > Signed-off-by: Linus Lüssing <linus.luessing@web.de> Applied. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2014-03-10 at 22:25 +0100, Linus Lüssing wrote: > 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. [...] That reminds me, shouldn't we also check this in igmp_rcv()? Ben.
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);
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 <jstancek@redhat.com> Signed-off-by: Linus Lüssing <linus.luessing@web.de> --- v2: simplified is_general_query variable assignment (thanks Cong!) net/bridge/br_multicast.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)