netdev - [PATCH 3/4 net-next] ip6_gre: use actual protocol to select xmit

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Date:   Mon, 11 Jul 2022 11:17:21 +0200
From:   Matthias May <matthias.may@...termo.com>
To:     <netdev@...r.kernel.org>
CC:     <davem@...emloft.net>, <yoshfuji@...ux-ipv6.org>,
        <dsahern@...nel.org>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <linux-kernel@...r.kernel.org>,
        Matthias May <matthias.may@...termo.com>
Subject: [PATCH 3/4 net-next] ip6_gre: use actual protocol to select xmit

When the payload is a VLAN encapsulated IPv6/IPv6 frame, we can
skip the 802.1q/802.1ad ethertypes and jump to the actual protocol.
This way we treat IPv4/IPv6 frames as IP instead of as "other".

Signed-off-by: Matthias May <matthias.may@...termo.com>
---
 net/ipv6/ip6_gre.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 5fe0db88bea8..cd0202016da0 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -916,6 +916,7 @@ static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb,
 {
 	struct ip6_tnl *t = netdev_priv(dev);
 	struct net_device_stats *stats = &t->dev->stats;
+	__be16 payload_protocol;
 	int ret;
 
 	if (!pskb_inet_may_pull(skb))
@@ -924,7 +925,8 @@ static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb,
 	if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
 		goto tx_err;
 
-	switch (skb->protocol) {
+	payload_protocol = skb_protocol(skb, true);
+	switch (payload_protocol) {
 	case htons(ETH_P_IP):
 		ret = ip6gre_xmit_ipv4(skb, dev);
 		break;
-- 
2.35.1