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net: ipv4: ip_forward: fix inverted local_df test

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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: fe6cc55f3a ("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>
This commit is contained in:
Florian Westphal 2014-05-04 23:24:31 +02:00 committed by David S. Miller
parent 4f4178f3bb
commit ca6c5d4ad2
1 changed files with 2 additions and 2 deletions
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4
net/ipv4/ip_forward.c
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@ -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)