[net-next v2] seg6: using DSCP of inner IPv4 packets

[net-next v2] 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@gmail.com>
---
 net/ipv6/seg6_iptunnel.c | 37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index e0e9f48ab14f..79abbfc95739 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -87,8 +87,7 @@ static void set_tun_src(struct net *net, struct net_device *dev,
 }
 
 /* Compute flowlabel for outer IPv6 header */
-static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
-				  struct ipv6hdr *inner_hdr)
+static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb)
 {
 	int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
 	__be32 flowlabel = 0;
@@ -99,7 +98,7 @@ static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
 		hash = rol32(hash, 16);
 		flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
 	} else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
-		flowlabel = ip6_flowlabel(inner_hdr);
+		flowlabel = ip6_flowlabel(ipv6_hdr(skb));
 	}
 	return flowlabel;
 }
@@ -109,10 +108,10 @@ 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 ipv6_sr_hdr *isrh;
 	int hdrlen, tot_len, err;
-	__be32 flowlabel;
+	struct ipv6hdr *hdr;
+	__be32 flowlabel, tos = 0;
 
 	hdrlen = (osrh->hdrlen + 1) << 3;
 	tot_len = hdrlen + sizeof(*hdr);
@@ -121,31 +120,31 @@ 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);
-	flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
-
-	skb_push(skb, tot_len);
-	skb_reset_network_header(skb);
-	skb_mac_header_rebuild(skb);
-	hdr = ipv6_hdr(skb);
-
 	/* inherit tc, flowlabel and hlim
 	 * hlim will be decremented in ip6_forward() afterwards and
 	 * decapsulation will overwrite inner hlim with outer hlim
 	 */
 
+	flowlabel = seg6_make_flowlabel(net, skb);
+
 	if (skb->protocol == htons(ETH_P_IPV6)) {
-		ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
-			     flowlabel);
-		hdr->hop_limit = inner_hdr->hop_limit;
+		tos = ip6_tclass(ip6_flowinfo(ipv6_hdr(skb)));
+	} else if (skb->protocol == htons(ETH_P_IP)) {
+		tos = ip_hdr(skb)->tos;
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 	} else {
-		ip6_flow_hdr(hdr, 0, flowlabel);
-		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
-
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 	}
 
+	skb_push(skb, tot_len);
+	skb_reset_network_header(skb);
+	skb_mac_header_rebuild(skb);
+	hdr = ipv6_hdr(skb);
+
+	ip6_flow_hdr(hdr, tos, flowlabel);
+
 	hdr->nexthdr = NEXTHDR_ROUTING;
+	hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
 
 	isrh = (void *)hdr + sizeof(*hdr);
 	memcpy(isrh, osrh, hdrlen);
-- 
2.17.1

Re: [net-next v2] seg6: using DSCP of inner IPv4 packets

[Jakub Kicinski]

On Mon,  3 Aug 2020 18:14:17 +0000 Ahmed Abdelsalam wrote:
> 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@gmail.com>

Please make sure it builds cleanly with W=1 C=1:

net/ipv6/seg6_iptunnel.c:131:21: warning: incorrect type in assignment (different base types)
net/ipv6/seg6_iptunnel.c:131:21:    expected restricted __be32 [usertype] tos
net/ipv6/seg6_iptunnel.c:131:21:    got unsigned char
net/ipv6/seg6_iptunnel.c:133:21: warning: incorrect type in assignment (different base types)
net/ipv6/seg6_iptunnel.c:133:21:    expected restricted __be32 [usertype] tos
net/ipv6/seg6_iptunnel.c:133:21:    got unsigned char [usertype] tos
net/ipv6/seg6_iptunnel.c:144:27: warning: incorrect type in argument 2 (different base types)
net/ipv6/seg6_iptunnel.c:144:27:    expected unsigned int tclass
net/ipv6/seg6_iptunnel.c:144:27:    got restricted __be32 [usertype] tos

Re: [net-next v2] seg6: using DSCP of inner IPv4 packets

[Ahmed Abdelsalam]

The problem was the declaration of tos.
Fixed and new patch is sent.

On 03/08/2020 21:48, Jakub Kicinski wrote:
> On Mon,  3 Aug 2020 18:14:17 +0000 Ahmed Abdelsalam wrote:
>> 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@gmail.com>
> 
> Please make sure it builds cleanly with W=1 C=1:
> 
> net/ipv6/seg6_iptunnel.c:131:21: warning: incorrect type in assignment (different base types)
> net/ipv6/seg6_iptunnel.c:131:21:    expected restricted __be32 [usertype] tos
> net/ipv6/seg6_iptunnel.c:131:21:    got unsigned char
> net/ipv6/seg6_iptunnel.c:133:21: warning: incorrect type in assignment (different base types)
> net/ipv6/seg6_iptunnel.c:133:21:    expected restricted __be32 [usertype] tos
> net/ipv6/seg6_iptunnel.c:133:21:    got unsigned char [usertype] tos
> net/ipv6/seg6_iptunnel.c:144:27: warning: incorrect type in argument 2 (different base types)
> net/ipv6/seg6_iptunnel.c:144:27:    expected unsigned int tclass
> net/ipv6/seg6_iptunnel.c:144:27:    got restricted __be32 [usertype] tos
>