Commit 418a3156 authored May 05, 2014 by Florian Westphal Committed by David S. Miller May 07, 2014

net: ipv6: send pkttoobig immediately if orig frag size > mtu



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: fe6cc55f ("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>

parent ca6c5d4a

net/ipv6/ip6_output.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -344,12 +344,16 @@ static unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)

		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;