[PATCH net-next v3 1/4] net: sched: em_ipt: match only on ip/ipv6 traffic

[Nikolay Aleksandrov <nikolay@cumulusnetworks.com>]

Restrict matching only to ip/ipv6 traffic and make sure we can use the
headers, otherwise matches will be attempted on any protocol which can
be unexpected by the xt matches. Currently policy supports only ipv4/6.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
v3: no change
v2: no change

 net/sched/em_ipt.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/net/sched/em_ipt.c b/net/sched/em_ipt.c
index 243fd22f2248..64dbafe4e94c 100644
--- a/net/sched/em_ipt.c
+++ b/net/sched/em_ipt.c
@@ -185,6 +185,19 @@ static int em_ipt_match(struct sk_buff *skb, struct tcf_ematch *em,
 	struct nf_hook_state state;
 	int ret;
 
+	switch (tc_skb_protocol(skb)) {
+	case htons(ETH_P_IP):
+		if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
+			return 0;
+		break;
+	case htons(ETH_P_IPV6):
+		if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
+			return 0;
+		break;
+	default:
+		return 0;
+	}
+
 	rcu_read_lock();
 
 	if (skb->skb_iif)
-- 
2.21.0