From 6a21165480a066a27c1f1dbd32aec581c612ba23 Mon Sep 17 00:00:00 2001 From: Andrew Lunn Date: Fri, 1 May 2015 16:39:54 +0200 Subject: [PATCH] net: ipv4: route: Fix sending IGMP messages with link address In setups with a global scope address on an interface, and a lesser scope address on an interface sending IGMP reports, the reports can be sent using the other interfaces global scope address rather than the local interface address. RFC 2236 suggests: Ignore the Report if you cannot identify the source address of the packet as belonging to a subnet assigned to the interface on which the packet was received. since such reports could be forged. Look at the protocol when deciding if a RT_SCOPE_LINK address should be used for the packet. Signed-off-by: Andrew Lunn Signed-off-by: David S. Miller --- net/ipv4/route.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 7cad0bf1c71c..9e15f5ca4495 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2091,7 +2091,8 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4) goto out; } if (ipv4_is_local_multicast(fl4->daddr) || - ipv4_is_lbcast(fl4->daddr)) { + ipv4_is_lbcast(fl4->daddr) || + fl4->flowi4_proto == IPPROTO_IGMP) { if (!fl4->saddr) fl4->saddr = inet_select_addr(dev_out, 0, RT_SCOPE_LINK);