ipv6: reuse ip6_frag_id from ip6_ufo_append_data

Currently we generate a new fragmentation id on UFO segmentation. It
is pretty hairy to identify the correct net namespace and dst there.
Especially tunnels use IFF_XMIT_DST_RELEASE and thus have no skb_dst
available at all.

This causes unreliable or very predictable ipv6 fragmentation id
generation while segmentation.

Luckily we already have pregenerated the ip6_frag_id in
ip6_ufo_append_data and can use it here.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index e7359f9..b261ee8 100644 (file)
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -113,7 +113,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
                fptr->nexthdr = nexthdr;
                fptr->reserved = 0;
-               ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
+               fptr->identification = skb_shinfo(skb)->ip6_frag_id;
 
                /* Fragment the skb. ipv6 header and the remaining fields of the
                 * fragment header are updated in ipv6_gso_segment()