This is a note to let you know that I've just added the patch titled
bridge: multicast: add sanity check for general query destination
to the 3.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bridge-multicast-add-sanity-check-for-general-query-destination.patch
and it can be found in the queue-3.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Apr 10 22:03:04 PDT 2014
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@xxxxxx>
Date: Mon, 10 Mar 2014 22:25:24 +0100
Subject: bridge: multicast: add sanity check for general query destination
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From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@xxxxxx>
[ 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 <jstancek@xxxxxxxxxx>
Signed-off-by: Linus Lüssing <linus.luessing@xxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/bridge/br_multicast.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1181,6 +1181,14 @@ static int br_ip4_multicast_query(struct
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
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
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);
Patches currently in stable-queue which might be from linus.luessing@xxxxxx are
queue-3.13/bridge-multicast-add-sanity-check-for-query-source.patch
queue-3.13/bridge-multicast-add-sanity-check-for-general-query-destination.patch
queue-3.13/bridge-multicast-enable-snooping-on-general-queries-only.patch
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