[net-next] seg6: using DSCP of inner IPv4 packets

[Ahmed Abdelsalam]

This patch allows copying the DSCP from inner IPv4 header to the
outer IPv6 header, when doing SRv6 Encapsulation.

This allows forwarding packet across the SRv6 fabric based on their
original traffic class.

Signed-off-by: Ahmed Abdelsalam <ahabdels@xxxxxxxxx>
---
 net/ipv6/seg6_iptunnel.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index e0e9f48ab14f..9753d10c4a51 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -110,6 +110,7 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 	struct dst_entry *dst = skb_dst(skb);
 	struct net *net = dev_net(dst->dev);
 	struct ipv6hdr *hdr, *inner_hdr;
+	struct iphdr *inner_ipv4_hdr;
 	struct ipv6_sr_hdr *isrh;
 	int hdrlen, tot_len, err;
 	__be32 flowlabel;
@@ -121,7 +122,11 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 	if (unlikely(err))
 		return err;
 
-	inner_hdr = ipv6_hdr(skb);
+	if (skb->protocol == htons(ETH_P_IPV6))
+		inner_hdr = ipv6_hdr(skb);
+	else
+		inner_ipv4_hdr = ip_hdr(skb);
+
 	flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
 
 	skb_push(skb, tot_len);
@@ -138,6 +143,10 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 		ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
 			     flowlabel);
 		hdr->hop_limit = inner_hdr->hop_limit;
+	} else if (skb->protocol == htons(ETH_P_IP)) {
+		ip6_flow_hdr(hdr, inner_ipv4_hdr->tos, flowlabel);
+		hdr->hop_limit = inner_ipv4_hdr->ttl;
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 	} else {
 		ip6_flow_hdr(hdr, 0, flowlabel);
 		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
-- 
2.17.1