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Commit b6f27d32 authored by Felix Fietkau's avatar Felix Fietkau Committed by Pablo Neira Ayuso
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netfilter: nf_flow_table: tear down TCP flows if RST or FIN was seen 



Allow the slow path to handle the shutdown of the connection with proper
timeouts. The packet containing RST/FIN is also sent to the slow path
and the TCP conntrack module will update its state.

Signed-off-by: default avatarFelix Fietkau <nbd@nbd.name>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent da5984e5

net/netfilter/nf_flow_table_ip.c

+27 −3
Original line number Diff line number Diff line
@@ -15,6 +15,23 @@ 
#include <linux/tcp.h>

#include <linux/udp.h>



static int nf_flow_tcp_state_check(struct flow_offload *flow,

				   struct sk_buff *skb, unsigned int thoff)

{

	struct tcphdr *tcph;



	if (!pskb_may_pull(skb, thoff + sizeof(*tcph)))

		return -1;



	tcph = (void *)(skb_network_header(skb) + thoff);

	if (unlikely(tcph->fin || tcph->rst)) {

		flow_offload_teardown(flow);

		return -1;

	}



	return 0;

}



static int nf_flow_nat_ip_tcp(struct sk_buff *skb, unsigned int thoff,

			      __be32 addr, __be32 new_addr)

{
@@ -119,10 +136,9 @@ static int nf_flow_dnat_ip(const struct flow_offload *flow, struct sk_buff *skb, 
}



static int nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,

			  enum flow_offload_tuple_dir dir)

			  unsigned int thoff, enum flow_offload_tuple_dir dir)

{

	struct iphdr *iph = ip_hdr(skb);

	unsigned int thoff = iph->ihl * 4;



	if (flow->flags & FLOW_OFFLOAD_SNAT &&

	    (nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
@@ -202,6 +218,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, 
	struct flow_offload *flow;

	struct net_device *outdev;

	const struct rtable *rt;

	unsigned int thoff;

	struct iphdr *iph;

	__be32 nexthop;
@@ -230,8 +247,12 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, 
	if (skb_try_make_writable(skb, sizeof(*iph)))

		return NF_DROP;



	thoff = ip_hdr(skb)->ihl * 4;

	if (nf_flow_tcp_state_check(flow, skb, thoff))

		return NF_ACCEPT;



	if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&

	    nf_flow_nat_ip(flow, skb, dir) < 0)

	    nf_flow_nat_ip(flow, skb, thoff, dir) < 0)

		return NF_DROP;



	flow->timeout = (u32)jiffies + NF_FLOW_TIMEOUT;
@@ -439,6 +460,9 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb, 
	if (unlikely(nf_flow_exceeds_mtu(skb, flow->tuplehash[dir].tuple.mtu)))

		return NF_ACCEPT;



	if (nf_flow_tcp_state_check(flow, skb, sizeof(*ip6h)))

		return NF_ACCEPT;



	if (skb_try_make_writable(skb, sizeof(*ip6h)))

		return NF_DROP;