[PATCH v4 net] geneve: fix TOS inheriting for ipv4

Matthias May posted 1 patch 6 days, 4 hours ago
drivers/net/geneve.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
[PATCH v4 net] geneve: fix TOS inheriting for ipv4
Posted by Matthias May 6 days, 4 hours ago
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.

Fixes: e305ac6cf5a1 ("geneve: Add support to collect tunnel metadata.")
Signed-off-by: Matthias May <matthias.may@westermo.com>
---
v1 -> v2:
 - Fix typo in "Fixes" tag
v2 -> v3:
 - Add missing CCs
v3 -> v4:
 - Drop reference to IPv6 equivalent of this patch (Guillaume Nault)
 - Return of full_tos in geneve_get_v4_rt only when needed (David Ahern))
---
 drivers/net/geneve.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 018d365f9deb..fafe7dea2227 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);
@@ -823,6 +824,8 @@ static struct rtable *geneve_get_v4_rt(struct sk_buff *skb,
 		use_cache = false;
 	}
 	fl4->flowi4_tos = RT_TOS(tos);
+	if (full_tos)
+		*full_tos = tos;
 
 	dst_cache = (struct dst_cache *)&info->dst_cache;
 	if (use_cache) {
@@ -911,6 +914,7 @@ 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;
@@ -921,7 +925,7 @@ 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);
 
@@ -965,7 +969,7 @@ 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
@@ -1149,7 +1153,7 @@ 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, NULL);
 		if (IS_ERR(rt))
 			return PTR_ERR(rt);
 
-- 
2.35.1
Re: [PATCH v4 net] geneve: fix TOS inheriting for ipv4
Posted by patchwork-bot+netdevbpf@kernel.org 1 day, 18 hours ago
Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 5 Aug 2022 21:00:06 +0200 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [v4,net] geneve: fix TOS inheriting for ipv4
    https://git.kernel.org/netdev/net/c/b4ab94d6adaa

You are awesome, thank you!
-- 
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Re: [PATCH v4 net] geneve: fix TOS inheriting for ipv4
Posted by Guillaume Nault 3 days, 11 hours ago
On Fri, Aug 05, 2022 at 09:00:06PM +0200, Matthias May wrote:
> 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.

Acked-by: Guillaume Nault <gnault@redhat.com>