From 5b18f1289808fee5d04a7e6ecf200189f41a4db6 Mon Sep 17 00:00:00 2001 From: Stephen Suryaputra Date: Wed, 26 Jun 2019 02:21:16 -0400 Subject: ipv4: reset rt_iif for recirculated mcast/bcast out pkts Multicast or broadcast egress packets have rt_iif set to the oif. These packets might be recirculated back as input and lookup to the raw sockets may fail because they are bound to the incoming interface (skb_iif). If rt_iif is not zero, during the lookup, inet_iif() function returns rt_iif instead of skb_iif. Hence, the lookup fails. v2: Make it non vrf specific (David Ahern). Reword the changelog to reflect it. Signed-off-by: Stephen Suryaputra Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/ip_output.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'net/ipv4/ip_output.c') diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 16f9159234a2..8c2ec35b6512 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -318,6 +318,7 @@ static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *sk static int ip_mc_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb) { + struct rtable *new_rt; int ret; ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb); @@ -326,6 +327,17 @@ static int ip_mc_finish_output(struct net *net, struct sock *sk, return ret; } + /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting + * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten, + * see ipv4_pktinfo_prepare(). + */ + new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb)); + if (new_rt) { + new_rt->rt_iif = 0; + skb_dst_drop(skb); + skb_dst_set(skb, &new_rt->dst); + } + return dev_loopback_xmit(net, sk, skb); } -- cgit v1.2.3