netdev - [PATCH net-next v2 08/12] ipv4: Unmask upper DSCP bits in ip_send_unicast

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Message-ID: <20240829065459.2273106-9-idosch@nvidia.com>
Date: Thu, 29 Aug 2024 09:54:55 +0300
From: Ido Schimmel <idosch@...dia.com>
To: <netdev@...r.kernel.org>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<edumazet@...gle.com>, <gnault@...hat.com>, <dsahern@...nel.org>,
	<ast@...nel.org>, <daniel@...earbox.net>, <martin.lau@...ux.dev>,
	<john.fastabend@...il.com>, <steffen.klassert@...unet.com>,
	<herbert@...dor.apana.org.au>, <bpf@...r.kernel.org>, Ido Schimmel
	<idosch@...dia.com>
Subject: [PATCH net-next v2 08/12] ipv4: Unmask upper DSCP bits in ip_send_unicast_reply()

The function calls flowi4_init_output() to initialize an IPv4 flow key
with which it then performs a FIB lookup using ip_route_output_flow().

'arg->tos' with which the TOS value in the IPv4 flow key (flowi4_tos) is
initialized contains the full DS field. Unmask the upper DSCP bits so
that in the future the FIB lookup could be performed according to the
full DSCP value.

Signed-off-by: Ido Schimmel <idosch@...dia.com>
Reviewed-by: Guillaume Nault <gnault@...hat.com>
---
 net/ipv4/ip_output.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b90d0f78ac80..eea443b7f65e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -77,6 +77,7 @@
 #include <net/inetpeer.h>
 #include <net/inet_ecn.h>
 #include <net/lwtunnel.h>
+#include <net/inet_dscp.h>
 #include <linux/bpf-cgroup.h>
 #include <linux/igmp.h>
 #include <linux/netfilter_ipv4.h>
@@ -1621,7 +1622,7 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 
 	flowi4_init_output(&fl4, oif,
 			   IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
-			   RT_TOS(arg->tos),
+			   arg->tos & INET_DSCP_MASK,
 			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
 			   ip_reply_arg_flowi_flags(arg),
 			   daddr, saddr,
-- 
2.46.0