From b6f27d322a0a7b588fe6369fa5fa87bd7c553bd3 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Mon, 26 Feb 2018 10:15:24 +0100 Subject: 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: Felix Fietkau Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_flow_table_ip.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) (limited to 'net/netfilter/nf_flow_table_ip.c') diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c index dc570fb7641d..692c75ef5cb7 100644 --- a/net/netfilter/nf_flow_table_ip.c +++ b/net/netfilter/nf_flow_table_ip.c @@ -15,6 +15,23 @@ #include #include +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; -- cgit v1.2.3-55-g7522