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[3.8,070/121] net: ipv6: send pkttoobig immediately if orig frag size > mtu

Message ID 1403021899-16708-43-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa June 17, 2014, 4:17 p.m. UTC 
3.8.13.24 -stable review patch.  If anyone has any objections, please let me know.

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

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 418a31561d594a2b636c1e2fa94ecd9e1245abb1 ]

If conntrack defragments incoming ipv6 frags it stores largest original
frag size in ip6cb and sets ->local_df.

We must thus first test the largest original frag size vs. mtu, and not
vice versa.

Without this patch PKTTOOBIG is still generated in ip6_fragment() later
in the stack, but

1) IPSTATS_MIB_INTOOBIGERRORS won't increment
2) packet did (needlessly) traverse netfilter postrouting hook.

Fixes: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 net/ipv6/ip6_output.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 64809bd..41abcf7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -368,12 +368,16 @@  static inline int ip6_forward_finish(struct sk_buff *skb)
 
 static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
 {
-	if (skb->len <= mtu || skb->local_df)
+	if (skb->len <= mtu)
 		return false;
 
+	/* ipv6 conntrack defrag sets max_frag_size + local_df */
 	if (IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)
 		return true;
 
+	if (skb->local_df)
+		return false;
+
 	if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
 		return false;