inherit inner IPv4 TTL on ip4ip6 SHR encapsulation like as inherit 
inner hop_limit on ip6ip6 SHR encapsulation

Signed-off-by: Yonglong Li <liyonglong@chinatelecom.cn>
---
 net/ipv6/seg6_iptunnel.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 098632a..2f1f9cf 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -160,7 +160,10 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 		hdr->hop_limit = inner_hdr->hop_limit;
 	} else {
 		ip6_flow_hdr(hdr, 0, flowlabel);
-		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
+		if (skb->protocol == htons(ETH_P_IP))
+			hdr->hop_limit = ((struct iphdr *)inner_hdr)->ttl;
+		else
+			hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
 
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 
@@ -249,7 +252,10 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
 		hdr->hop_limit = inner_hdr->hop_limit;
 	} else {
 		ip6_flow_hdr(hdr, 0, flowlabel);
-		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
+		if (skb->protocol == htons(ETH_P_IP))
+			hdr->hop_limit = ((struct iphdr *)inner_hdr)->ttl;
+		else
+			hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
 
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 		IP6CB(skb)->iif = skb->skb_iif;
-- 
1.8.3.1

On Thu, 16 Jan 2025 10:40:36 +0800 Yonglong Li wrote:
> inherit inner IPv4 TTL on ip4ip6 SHR encapsulation like as inherit 
> inner hop_limit on ip6ip6 SHR encapsulation

Could you add some references to RFCs which recommend this behavior 
to the commit message?
-- 
pw-bot: cr