netdev - [PATCH v3 net 4/4] ipv6: do not use RT

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Message-ID: <20220805191906.9323-5-matthias.may@westermo.com>
Date:   Fri, 5 Aug 2022 21:19:06 +0200
From:   Matthias May <matthias.may@...termo.com>
To:     <netdev@...r.kernel.org>
CC:     <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <roopa@...dia.com>,
        <eng.alaamohamedsoliman.am@...il.com>, <bigeasy@...utronix.de>,
        <saeedm@...dia.com>, <leon@...nel.org>, <roid@...dia.com>,
        <maord@...dia.com>, <lariel@...dia.com>, <vladbu@...dia.com>,
        <cmi@...dia.com>, <gnault@...hat.com>, <yoshfuji@...ux-ipv6.org>,
        <dsahern@...nel.org>, <linux-kernel@...r.kernel.org>,
        <bpf@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
        <nicolas.dichtel@...nd.com>, <eyal.birger@...il.com>,
        <jesse@...ira.com>, <linville@...driver.com>,
        <daniel@...earbox.net>, <hadarh@...lanox.com>,
        <ogerlitz@...lanox.com>, <willemb@...gle.com>,
        <martin.varghese@...ia.com>,
        Matthias May <matthias.may@...termo.com>
Subject: [PATCH v3 net 4/4] ipv6: do not use RT_TOS for IPv6 flowlabel

According to Guillaume Nault RT_TOS should never be used for IPv6.

Quote:
RT_TOS() is an old macro used to interprete IPv4 TOS as described in
the obsolete RFC 1349. It's conceptually wrong to use it even in IPv4
code, although, given the current state of the code, most of the
existing calls have no consequence.

But using RT_TOS() in IPv6 code is always a bug: IPv6 never had a "TOS"
field to be interpreted the RFC 1349 way. There's no historical
compatibility to worry about.

Fixes: 571912c69f0e ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Acked-by: Guillaume Nault <gnault@...hat.com>
Signed-off-by: Matthias May <matthias.may@...termo.com>
---
v1 -> v2:
 - Fix spacing of "Fixes" tag.
 - Add missing CCs
v2 -> v3:
 - Add the info from the cover to the actual patch message (Guillaume Nault)
---
 net/ipv6/ip6_output.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 77e3f5970ce4..ec62f472aa1c 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1311,8 +1311,7 @@ struct dst_entry *ip6_dst_lookup_tunnel(struct sk_buff *skb,
 	fl6.daddr = info->key.u.ipv6.dst;
 	fl6.saddr = info->key.u.ipv6.src;
 	prio = info->key.tos;
-	fl6.flowlabel = ip6_make_flowinfo(RT_TOS(prio),
-					  info->key.label);
+	fl6.flowlabel = ip6_make_flowinfo(prio, info->key.label);
 
 	dst = ipv6_stub->ipv6_dst_lookup_flow(net, sock->sk, &fl6,
 					      NULL);
-- 
2.35.1