netdev - [PATCH net 3/3] netfilter: Use flowlabel flow key when re-routing mangled packets

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Date: Wed, 12 Jun 2024 00:03:23 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net,
	netdev@...r.kernel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	fw@...len.de
Subject: [PATCH net 3/3] netfilter: Use flowlabel flow key when re-routing mangled packets

From: Florian Westphal <fw@...len.de>

'ip6 dscp set $v' in an nftables outpute route chain has no effect.
While nftables does detect the dscp change and calls the reroute hook.
But ip6_route_me_harder never sets the dscp/flowlabel:
flowlabel/dsfield routing rules are ignored and no reroute takes place.

Thanks to Yi Chen for an excellent reproducer script that I used
to validate this change.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Yi Chen <yiche@...hat.com>
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/ipv6/netfilter.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 53d255838e6a..5d989d803009 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -36,6 +36,7 @@ int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff
 		.flowi6_uid = sock_net_uid(net, sk),
 		.daddr = iph->daddr,
 		.saddr = iph->saddr,
+		.flowlabel = ip6_flowinfo(iph),
 	};
 	int err;
 
-- 
2.30.2