netdev - [PATCH 2/4 net-next] ip6_gre: set DSCP for non-IP

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Date:   Mon, 11 Jul 2022 11:17:20 +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>, <linux-kernel@...r.kernel.org>,
        Matthias May <matthias.may@...termo.com>
Subject: [PATCH 2/4 net-next] ip6_gre: set DSCP for non-IP

The current code always forces a dscp of 0 for all non-IP frames.
However when setting a specific TOS with the command

ip link add name tep0 type ip6gretap local fdd1:ced0:5d88:3fce::1
remote fdd1:ced0:5d88:3fce::2 tos 0xa0

one would expect all GRE encapsulated frames to have a TOS of 0xA0.
and not only when the payload is IPv4/IPv6.

Signed-off-by: Matthias May <matthias.may@...termo.com>
---
 net/ipv6/ip6_gre.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index a9051df0625d..5fe0db88bea8 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -701,6 +701,33 @@ static int prepare_ip6gre_xmit_ipv6(struct sk_buff *skb,
 	return 0;
 }
 
+static int prepare_ip6gre_xmit_other(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct flowi6 *fl6, __u8 *dsfield,
+				     int *encap_limit)
+{
+	struct ip6_tnl *t = netdev_priv(dev);
+
+	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
+		*encap_limit = t->parms.encap_limit;
+
+	memcpy(fl6, &t->fl.u.ip6, sizeof(*fl6));
+
+	if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
+		*dsfield = 0;
+	else
+		*dsfield = ip6_tclass(t->parms.flowinfo);
+
+	if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
+		fl6->flowi6_mark = skb->mark;
+	else
+		fl6->flowi6_mark = t->parms.fwmark;
+
+	fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);
+
+	return 0;
+}
+
 static struct ip_tunnel_info *skb_tunnel_info_txcheck(struct sk_buff *skb)
 {
 	struct ip_tunnel_info *tun_info;
@@ -868,20 +895,18 @@ static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev)
 	struct ip6_tnl *t = netdev_priv(dev);
 	int encap_limit = -1;
 	struct flowi6 fl6;
+	__u8 dsfield = 0;
 	__u32 mtu;
 	int err;
 
-	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
-		encap_limit = t->parms.encap_limit;
-
-	if (!t->parms.collect_md)
-		memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
+	if (!t->parms.collect_md &&
+	    prepare_ip6gre_xmit_other(skb, dev, &fl6, &dsfield, &encap_limit))
+		return -1;
 
 	err = gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM));
 	if (err)
 		return err;
-
-	err = __gre6_xmit(skb, dev, 0, &fl6, encap_limit, &mtu, skb->protocol);
+	err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu, skb->protocol);
 
 	return err;
 }
-- 
2.35.1