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IGMP snooping: set mrouters_only flag for IPv4 traffic properly 

Upon reception of a IGMP/IGMPv2 membership report the kernel sets the
mrouters_only flag in a skb that may be a clone of the original skb, which
means that sometimes the bridge loses track of membership report packets (cb
buffers are tied to a specific skb and not shared) and it ends up forwading
join requests to the bridge interface.

This can cause unexpected membership timeouts and intermitent/permanent loss
of connectivity as described in RFC 4541 [2.1.1. IGMP Forwarding Rules]:

    A snooping switch should forward IGMP Membership Reports only to
    those ports where multicast routers are attached.
    [...]
    Sending membership reports to other hosts can result, for IGMPv1
    and IGMPv2, in unintentionally preventing a host from joining a
    specific multicast group.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Tested-by: Hayato Kakuta <kakuta.hayato@oss.ntt.co.jp>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>
This commit is contained in:
Fernando Luis Vázquez Cao 2011-06-13 15:04:43 +00:00 committed by David S. Miller
parent d40261236e
commit 62b2bcb49c
1 changed files with 1 additions and 1 deletions
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2
net/bridge/br_multicast.c
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@ -1424,7 +1424,7 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br,
switch (ih->type) {
case IGMP_HOST_MEMBERSHIP_REPORT:
case IGMPV2_HOST_MEMBERSHIP_REPORT:
BR_INPUT_SKB_CB(skb2)->mrouters_only = 1;
BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
err = br_ip4_multicast_add_group(br, port, ih->group);
break;
case IGMPV3_HOST_MEMBERSHIP_REPORT: