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    Subject[PATCH net-next 1/2] 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 bbcb435..662ba7b 100644
    --- a/net/bridge/br_multicast.c
    +++ b/net/bridge/br_multicast.c
    @@ -1547,8 +1547,14 @@ 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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