Commit ca6c5d4a authored May 04, 2014 by Florian Westphal Committed by David S. Miller May 07, 2014

net: ipv4: ip_forward: fix inverted local_df test



local_df means 'ignore DF bit if set', so if its set we're
allowed to perform ip fragmentation.

This wasn't noticed earlier because the output path also drops such skbs
(and emits needed icmp error) and because netfilter ip defrag did not
set local_df until couple of days ago.

Only difference is that DF-packets-larger-than MTU now discarded
earlier (f.e. we avoid pointless netfilter postrouting trip).

While at it, drop the repeated test ip_exceeds_mtu, checking it once
is enough...

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 4f4178f3

net/ipv4/ip_forward.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -42,12 +42,12 @@
		static bool ip_may_fragment(const struct sk_buff *skb)
		{
		return unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0) \|\|
		!skb->local_df;
		skb->local_df;
		}

		static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
		{
		if (skb->len <= mtu \|\| skb->local_df)
		if (skb->len <= mtu)
		return false;

		if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)

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