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From: Felix Fietkau <nbd@nbd.name>
Date: Fri, 23 Mar 2018 17:15:22 +0100
Subject: [PATCH] netfilter: nf_flow_table: add missing condition for TCP state
check
Avoid looking at unrelated fields in UDP packets
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -15,11 +15,14 @@
#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)
+static int nf_flow_state_check(struct flow_offload *flow, int proto,
+ struct sk_buff *skb, unsigned int thoff)
{
struct tcphdr *tcph;
+ if (proto != IPPROTO_TCP)
+ return 0;
+
if (!pskb_may_pull(skb, thoff + sizeof(*tcph)))
return -1;
@@ -248,7 +251,7 @@ nf_flow_offload_ip_hook(void *priv, stru
return NF_DROP;
thoff = ip_hdr(skb)->ihl * 4;
- if (nf_flow_tcp_state_check(flow, skb, thoff))
+ if (nf_flow_state_check(flow, ip_hdr(skb)->protocol, skb, thoff))
return NF_ACCEPT;
if (flow->flags & (FLOW_OFFLOAD_SNAT | FLOW_OFFLOAD_DNAT) &&
@@ -460,7 +463,8 @@ 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)))
+ if (nf_flow_state_check(flow, ipv6_hdr(skb)->nexthdr, skb,
+ sizeof(*ip6h)))
return NF_ACCEPT;
if (skb_try_make_writable(skb, sizeof(*ip6h)))
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