linux-kernel - [PATCH 4.19 04/90] netfilter: nf_flow

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Date:   Mon,  8 Jul 2019 17:12:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 4.19 04/90] netfilter: nf_flow_table: ignore DF bit setting

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

commit e75b3e1c9bc5b997d09bdf8eb72ab3dd3c1a7072 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/nf_flow_table_ip.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -246,8 +246,7 @@ nf_flow_offload_ip_hook(void *priv, stru
 	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
 	rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache;
 
-	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)))