linux-kernel - [PATCH 4.4 049/149] Revert "vxlan: fix tos value before xmit"

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Date:   Thu, 20 Aug 2020 11:22:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hangbin Liu <liuhangbin@...il.com>,
        Guillaume Nault <gnault@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 049/149] Revert "vxlan: fix tos value before xmit"

From: Hangbin Liu <liuhangbin@...il.com>

[ Upstream commit a0dced17ad9dc08b1b25e0065b54c97a318e6e8b ]

This reverts commit 71130f29979c7c7956b040673e6b9d5643003176.

In commit 71130f29979c ("vxlan: fix tos value before xmit") we want to
make sure the tos value are filtered by RT_TOS() based on RFC1349.

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |   PRECEDENCE    |          TOS          | MBZ |
    +-----+-----+-----+-----+-----+-----+-----+-----+

But RFC1349 has been obsoleted by RFC2474. The new DSCP field defined like

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |          DS FIELD, DSCP           | ECN FIELD |
    +-----+-----+-----+-----+-----+-----+-----+-----+

So with

IPTOS_TOS_MASK          0x1E
RT_TOS(tos)		((tos)&IPTOS_TOS_MASK)

the first 3 bits DSCP info will get lost.

To take all the DSCP info in xmit, we should revert the patch and just push
all tos bits to ip_tunnel_ecn_encap(), which will handling ECN field later.

Fixes: 71130f29979c ("vxlan: fix tos value before xmit")
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
Acked-by: Guillaume Nault <gnault@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/vxlan.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2070,7 +2070,7 @@ static void vxlan_xmit_one(struct sk_buf
 			return;
 		}
 
-		tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb);
+		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
 		err = vxlan_xmit_skb(rt, sk, skb, fl4.saddr,
 				     dst->sin.sin_addr.s_addr, tos, ttl, df,