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Subject[PATCH] bridge: prevent flooding IPv6 packets that do not have a listener
Date
Currently if there is no listener for a certain group then IPv6 packets
for that group are flooded on all ports, even though there might be no
host and router interested in it on a port.

With this commit they are only forwarded to ports with a multicast
router.

Just like commit bd4265fe36 ("bridge: Only flood unregistered groups
to routers") did for IPv4, let's do the same for IPv6 with the same
reasoning.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
net/bridge/br_multicast.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 81f2389..8bdfaf5 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1465,8 +1465,14 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
* - MLD has always Router Alert hop-by-hop option
* - But we do not support jumbrograms.
*/
- if (ip6h->version != 6 ||
- ip6h->nexthdr != IPPROTO_HOPOPTS ||
+ if (ip6h->version != 6)
+ return 0;
+
+ /* Prevent flooding this packet if there is no listener present */
+ if (ipv6_is_transient_multicast(&ip6h->daddr))
+ BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
+
+ if (ip6h->nexthdr != IPPROTO_HOPOPTS ||
ip6h->payload_len == 0)
return 0;

--
1.7.10.4
--
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