From dfe42be15fde16232340b8b2a57c359f51cc10d9 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 13 Aug 2019 17:41:13 +0200 Subject: [PATCH] netfilter: nft_flow_offload: skip tcp rst and fin packets TCP rst and fin packets do not qualify to place a flow into the flowtable. Most likely there will be no more packets after connection closure. Without this patch, this flow entry expires and connection tracking picks up the entry in ESTABLISHED state using the fixup timeout, which makes this look inconsistent to the user for a connection that is actually already closed. Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_flow_offload.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c index aa5f571d4361..060a4ed46d5e 100644 --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -72,11 +72,11 @@ static void nft_flow_offload_eval(const struct nft_expr *expr, { struct nft_flow_offload *priv = nft_expr_priv(expr); struct nf_flowtable *flowtable = &priv->flowtable->data; + struct tcphdr _tcph, *tcph = NULL; enum ip_conntrack_info ctinfo; struct nf_flow_route route; struct flow_offload *flow; enum ip_conntrack_dir dir; - bool is_tcp = false; struct nf_conn *ct; int ret; @@ -89,7 +89,10 @@ static void nft_flow_offload_eval(const struct nft_expr *expr, switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) { case IPPROTO_TCP: - is_tcp = true; + tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, + sizeof(_tcph), &_tcph); + if (unlikely(!tcph || tcph->fin || tcph->rst)) + goto out; break; case IPPROTO_UDP: break; @@ -115,7 +118,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr, if (!flow) goto err_flow_alloc; - if (is_tcp) { + if (tcph) { ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL; ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL; }