IGMP snooping: set mrouters_only flag for IPv4 traffic properly
authorFernando Luis Vázquez Cao <fernando@oss.ntt.co.jp>
Mon, 13 Jun 2011 15:04:43 +0000 (15:04 +0000)
committerDavid S. Miller <davem@conan.davemloft.net>
Fri, 17 Jun 2011 03:14:12 +0000 (23:14 -0400)
commit62b2bcb49cca72f6d3f39f831127a6ab315a475d
treeedb756747c2fcabb74d8422a7adb84e3a7bb3386
parentd40261236e8e278cb1936cb5e934262971692b10
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>
net/bridge/br_multicast.c