netdev - [PATCH 07/11] netfilter: nf_flow_table: ignore DF bit setting

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Message-Id: <20190523213547.15523-8-pablo@netfilter.org>
Date:   Thu, 23 May 2019 23:35:43 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 07/11] netfilter: nf_flow_table: ignore DF bit setting

From: Florian Westphal <fw@...len.de>

Its irrelevant if the DF bit is set or not, we must pass packet to
stack in either case.

If the DF bit is set, we must pass it to stack so the appropriate
ICMP error can be generated.

If the DF is not set, we must pass it to stack for fragmentation.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_flow_table_ip.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
index 0d603e20b519..bfd44db9f214 100644
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -243,8 +243,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 	rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
 	outdev = rt->dst.dev;
 
-	if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)) &&
-	    (ip_hdr(skb)->frag_off & htons(IP_DF)) != 0)
+	if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))
 		return NF_ACCEPT;
 
 	if (skb_try_make_writable(skb, sizeof(*iph)))
-- 
2.11.0