[PATCH nf] netfilter: Use flowlabel flow key when re-routing mangled packets

[PATCH nf] netfilter: Use flowlabel flow key when re-routing mangled packets

[Florian Westphal]

'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@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 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;
 
-- 
2.44.2

Re: [PATCH nf] netfilter: Use flowlabel flow key when re-routing mangled packets

[Pablo Neira Ayuso]

On Thu, Jun 06, 2024 at 12:23:31PM +0200, Florian Westphal wrote:
> '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.

Applied to nf.git, thanks Florian