From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust filename, indentation]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
This is a dependency of commit 73f156a6e8c1 ("inetpeer: get rid of
ip_id_count") which was already backported into 3.2.63 and 3.4.103.
Applying that on its own introduced this bug:
<https://bugs.debian.org/766195>.
All other stable branches have both or neither of the commits.
After applying this, there is a remaining regression that also affects
upstream and should be fixed there shortly:
<http://patchwork.ozlabs.org/patch/403358/>,
<http://patchwork.ozlabs.org/patch/403359/>.
Ben.
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1362,7 +1362,7 @@ static struct sk_buff *udp6_ufo_fragment
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()
--
Ben Hutchings
Theory and practice are closer in theory than in practice.
- John Levine, moderator of comp.compilers
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