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From:   Matthias May <matthias.may@westermo.com>
To:     <netdev@vger.kernel.org>
CC:     <davem@davemloft.net>, <yoshfuji@linux-ipv6.org>,
        <dsahern@kernel.org>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <nicolas.dichtel@6wind.com>,
        <eyal.birger@gmail.com>, <linux-kernel@vger.kernel.org>,
        Matthias May <matthias.may@westermo.com>
Subject: [PATCH net] geneve: fix TOS inheriting for ipv4
Date:   Tue, 2 Aug 2022 13:25:53 +0200
Message-ID: <20220802112553.1360668-1-matthias.may@westermo.com>
MIME-Version: 1.0
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Precedence: bulk

The current code retrieves the TOS field after the lookup
on the ipv4 routing table. The routing process currently
only allows routing based on the original 3 TOS bits, and
not on the full 6 DSCP bits.
As a result the retrieved TOS is cut to the 3 bits.
However for inheriting purposes the full 6 bits should be used.

Extract the full 6 bits before the route lookup and use
that instead of the cut off 3 TOS bits.

This patch is the functional equivalent for IPv4 to the patch
"geneve: do not use RT_TOS for IPv6 flowlabel"

Fixed: e305ac6cf5a1 ("geneve: Add support to collect tunnel metadata.")

Signed-off-by: Matthias May <matthias.may@westermo.com>
---
 drivers/net/geneve.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 2495a5719e1c..4c380c06f178 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -797,7 +797,8 @@ static struct rtable *geneve_get_v4_rt(struct sk_buff *skb,
 				       struct geneve_sock *gs4,
 				       struct flowi4 *fl4,
 				       const struct ip_tunnel_info *info,
-				       __be16 dport, __be16 sport)
+				       __be16 dport, __be16 sport,
+				       __u8 *full_tos)
 {
 	bool use_cache = ip_tunnel_dst_cache_usable(skb, info);
 	struct geneve_dev *geneve = netdev_priv(dev);
@@ -822,6 +823,7 @@ static struct rtable *geneve_get_v4_rt(struct sk_buff *skb,
 		use_cache = false;
 	}
 	fl4->flowi4_tos = RT_TOS(tos);
+	*full_tos = tos;
 
 	dst_cache = (struct dst_cache *)&info->dst_cache;
 	if (use_cache) {
@@ -910,6 +912,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	const struct ip_tunnel_key *key = &info->key;
 	struct rtable *rt;
 	struct flowi4 fl4;
+	__u8 full_tos;
 	__u8 tos, ttl;
 	__be16 df = 0;
 	__be16 sport;
@@ -920,7 +923,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 
 	sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
 	rt = geneve_get_v4_rt(skb, dev, gs4, &fl4, info,
-			      geneve->cfg.info.key.tp_dst, sport);
+			      geneve->cfg.info.key.tp_dst, sport, &full_tos);
 	if (IS_ERR(rt))
 		return PTR_ERR(rt);
 
@@ -964,7 +967,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 
 		df = key->tun_flags & TUNNEL_DONT_FRAGMENT ? htons(IP_DF) : 0;
 	} else {
-		tos = ip_tunnel_ecn_encap(fl4.flowi4_tos, ip_hdr(skb), skb);
+		tos = ip_tunnel_ecn_encap(full_tos, ip_hdr(skb), skb);
 		if (geneve->cfg.ttl_inherit)
 			ttl = ip_tunnel_get_ttl(ip_hdr(skb), skb);
 		else
@@ -1137,6 +1140,7 @@ static int geneve_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 {
 	struct ip_tunnel_info *info = skb_tunnel_info(skb);
 	struct geneve_dev *geneve = netdev_priv(dev);
+	__u8 full_tos;
 	__be16 sport;
 
 	if (ip_tunnel_info_af(info) == AF_INET) {
@@ -1148,7 +1152,8 @@ static int geneve_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 					  1, USHRT_MAX, true);
 
 		rt = geneve_get_v4_rt(skb, dev, gs4, &fl4, info,
-				      geneve->cfg.info.key.tp_dst, sport);
+				      geneve->cfg.info.key.tp_dst, sport,
+				      &full_tos);
 		if (IS_ERR(rt))
 			return PTR_ERR(rt);
 
-- 
2.35.1