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- From: Felix Fietkau <nbd@nbd.name>
- Date: Sun, 25 Feb 2018 15:42:58 +0100
- Subject: [PATCH] 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
- Signed-off-by: Felix Fietkau <nbd@nbd.name>
- ---
- --- a/net/netfilter/nf_flow_table_ip.c
- +++ b/net/netfilter/nf_flow_table_ip.c
- @@ -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)
- {
- @@ -118,10 +135,9 @@ static int nf_flow_dnat_ip(const struct
- }
-
- 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 ||
- @@ -201,6 +217,7 @@ nf_flow_offload_ip_hook(void *priv, stru
- struct flow_offload *flow;
- struct net_device *outdev;
- const struct rtable *rt;
- + unsigned int thoff;
- struct iphdr *iph;
- __be32 nexthop;
-
- @@ -229,8 +246,12 @@ nf_flow_offload_ip_hook(void *priv, stru
- 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;
- @@ -438,6 +459,9 @@ nf_flow_offload_ipv6_hook(void *priv, st
- 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;
-
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