From 1f68835d92bbfe3a14d369d3dce123c94521b105 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 4 May 2014 23:24:31 +0200 Subject: [PATCH] net: ipv4: ip_forward: fix inverted local_df test [ Upstream commit ca6c5d4ad216d5942ae544bbf02503041bd802aa ] 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: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path") Signed-off-by: Florian Westphal Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ip_forward.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c index f3869c1..1c6bd43 100644 --- a/net/ipv4/ip_forward.c +++ b/net/ipv4/ip_forward.c @@ -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) -- 2.7.4