linux-kernel - [PATCH net-next] ip_tunnels: allow VXLAN/GENEVE to inherit TOS/TTL from VLAN

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Message-ID: <20220721202718.10092-1-matthias.may@westermo.com>
Date:   Thu, 21 Jul 2022 22:27:19 +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>, <nicolas.dichtel@...nd.com>,
        <eyal.birger@...il.com>, <linux-kernel@...r.kernel.org>,
        Matthias May <matthias.may@...termo.com>
Subject: [PATCH net-next] ip_tunnels: allow VXLAN/GENEVE to inherit TOS/TTL from VLAN

The current code allows for VXLAN and GENEVE to inherit the TOS
respective the TTL when skb-protocol is ETH_P_IP or ETH_P_IPV6.
However when the payload is VLAN encapsulated, then this inheriting
does not work, because the visible skb-protocol is of type
ETH_P_8021Q or ETH_P_8021AD.

Instead of skb->protocol use skb_protocol().

Signed-off-by: Matthias May <matthias.may@...termo.com>
---
 include/net/ip_tunnels.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index c24fa934221d..d76c3f6a1f3f 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -387,9 +387,11 @@ static inline int ip_tunnel_encap(struct sk_buff *skb, struct ip_tunnel *t,
 static inline u8 ip_tunnel_get_dsfield(const struct iphdr *iph,
 				       const struct sk_buff *skb)
 {
-	if (skb->protocol == htons(ETH_P_IP))
+	__be16 payload_protocol = skb_protocol(skb, true);
+
+	if (payload_protocol == htons(ETH_P_IP))
 		return iph->tos;
-	else if (skb->protocol == htons(ETH_P_IPV6))
+	else if (payload_protocol == htons(ETH_P_IPV6))
 		return ipv6_get_dsfield((const struct ipv6hdr *)iph);
 	else
 		return 0;
@@ -398,9 +400,11 @@ static inline u8 ip_tunnel_get_dsfield(const struct iphdr *iph,
 static inline u8 ip_tunnel_get_ttl(const struct iphdr *iph,
 				       const struct sk_buff *skb)
 {
-	if (skb->protocol == htons(ETH_P_IP))
+	__be16 payload_protocol = skb_protocol(skb, true);
+
+	if (payload_protocol == htons(ETH_P_IP))
 		return iph->ttl;
-	else if (skb->protocol == htons(ETH_P_IPV6))
+	else if (payload_protocol == htons(ETH_P_IPV6))
 		return ((const struct ipv6hdr *)iph)->hop_limit;
 	else
 		return 0;
-- 
2.35.1