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>

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index bf66a86..b99d806 100644 (file)
--- 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;
 }