ipvs: fix ipv6 route unreach panic

Previously there was a trivial panic

unshare -n /bin/bash <<EOF
ip addr add dev lo face::1/128
ipvsadm -A -t [face::1]:15213
ipvsadm -a -t [face::1]:15213 -r b00c::1
echo boom | nc face::1 15213
EOF

This patch allows us to replicate the net logic above and simply capture
the skb_dst(skb)->dev and use that for the purpose of the invocation.

Signed-off-by: Alex Gartrell <agartrell@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index bf66a8657a5f..b99d80695b1f 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -505,6 +505,13 @@ err_put:
         return -1;
 
 err_unreach:
+        /* The ip6_link_failure function requires the dev field to be set
+         * in order to get the net (further for the sake of fwmark
+         * reflection).
+         */
+        if (!skb->dev)
+                skb->dev = skb_dst(skb)->dev;
+
         dst_link_failure(skb);
         return -1;
 }