From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fernando Luis Vazquez Cao Subject: IGMP snooping: set mrouters_only flag for IPv4 traffic properly Date: Mon, 13 Jun 2011 12:02:43 +0900 Message-ID: <1307934163.3550.2.camel@nausicaa> References: <1307933995.2704.11.camel@nausicaa> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , netdev@vger.kernel.org, Hayato Kakuta To: Herbert Xu Return-path: Received: from serv2.oss.ntt.co.jp ([222.151.198.100]:41996 "EHLO serv2.oss.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380Ab1FMDCo (ORCPT ); Sun, 12 Jun 2011 23:02:44 -0400 In-Reply-To: <1307933995.2704.11.camel@nausicaa> Sender: netdev-owner@vger.kernel.org List-ID: 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 specifici 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 Tested-by: Hayato Kakuta --- diff -urNp linux-3.0-rc2-orig/net/bridge/br_multicast.c linux-3.0-rc2/net/bridge/br_multicast.c --- linux-3.0-rc2-orig/net/bridge/br_multicast.c 2011-06-09 13:34:04.164261031 +0900 +++ linux-3.0-rc2/net/bridge/br_multicast.c 2011-06-09 20:04:23.473930447 +0900 @@ -1424,7 +1424,7 @@ static int br_multicast_ipv4_rcv(struct 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: