From: Florian Westphal <fw@xxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
[ 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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
net/ipv6/ip6_output.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 516e136f15ca..45010f0d1167 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -323,12 +323,16 @@ 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;
--
1.9.3
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