From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: [PATCH] net: ipv6: send pkttoobig immediately if orig frag size > mtu Date: Mon, 5 May 2014 00:03:34 +0200 Message-ID: <1399241014-32471-1-git-send-email-fw@strlen.de> Cc: Florian Westphal To: netdev@vger.kernel.org Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:34891 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753811AbaEDWIy (ORCPT ); Sun, 4 May 2014 18:08:54 -0400 Sender: netdev-owner@vger.kernel.org List-ID: 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 --- 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 40e7581..31a38bd 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -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; -- 1.8.1.5