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@westermo.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

Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 21 Jul 2022 22:27:19 +0200 you wrote:
> 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().
> 
> [...]

Here is the summary with links:
  - [net-next] ip_tunnels: allow VXLAN/GENEVE to inherit TOS/TTL from VLAN
    https://git.kernel.org/netdev/net-next/c/7074732c8fae

You are awesome, thank you!
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