Commit 6565b9ee authored by Linus Lüssing's avatar Linus Lüssing Committed by David S. Miller

bridge: multicast: add sanity check for query source addresses

MLD queries are supposed to have an IPv6 link-local source address
according to RFC2710, section 4 and RFC3810, section 5.1.14. This patch
adds a sanity check to ignore such broken MLD queries.

Without this check, such malformed MLD queries can result in a
denial of service: The queries are ignored by any MLD listener
therefore they will not respond with an 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: default avatarJan Stancek <jstancek@redhat.com>
Signed-off-by: default avatarLinus Lüssing <linus.luessing@web.de>
Reviewed-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 24b9bf43
...@@ -1235,6 +1235,12 @@ static int br_ip6_multicast_query(struct net_bridge *br, ...@@ -1235,6 +1235,12 @@ static int br_ip6_multicast_query(struct net_bridge *br,
(port && port->state == BR_STATE_DISABLED)) (port && port->state == BR_STATE_DISABLED))
goto out; goto out;
/* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
if (!(ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL)) {
err = -EINVAL;
goto out;
}
if (skb->len == sizeof(*mld)) { if (skb->len == sizeof(*mld)) {
if (!pskb_may_pull(skb, sizeof(*mld))) { if (!pskb_may_pull(skb, sizeof(*mld))) {
err = -EINVAL; err = -EINVAL;
......
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