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>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
index 692c75e..82451b7 100644 (file)
--- 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, struct sk_buff *skb,
                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, 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)))
+       if (nf_flow_state_check(flow, ipv6_hdr(skb)->nexthdr, skb,
+                               sizeof(*ip6h)))
                return NF_ACCEPT;
 
        if (skb_try_make_writable(skb, sizeof(*ip6h)))