[PATCH 3.4 88/91] ipv6: reuse ip6_frag_id from ip6_ufo_append_data

[lizf]

From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>

3.4.105-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 916e4cf46d0204806c062c8c6c4d1f633852c5b6 upstream.

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>
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 net/ipv6/udp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 98fd738..ef9052f 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1366,7 +1366,7 @@ 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()
-- 
1.9.1

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