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Date: Wed, 18 Sep 2024 10:42:02 +0200
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Antonio Ojea <antonio.ojea.garcia@gmail.com>,
	netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nf] netfilter: nfnetlink_queue: reroute reinjected
 packets from postrouting
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References: <20240912185832.11962-1-pablo@netfilter.org>
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User-Agent: Mutt/1.10.1 (2018-07-13)

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > Ok, I finally managed to get this tested, and it does not seem to
> > solve the problem, it keeps dnating twice after the packet is enqueued
> > by nfqueue
> 
> dnatting twice is required to deal with the conntrack confirmation race.

Antonio could also try this hack:

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -379,7 +379,7 @@ static void nfqnl_reinject(struct nf_queue_entry *entry, unsigned int verdict)
                unsigned int ct_verdict = verdict;
 
                rcu_read_lock();
-               ct_hook = rcu_dereference(nf_ct_hook);
+               ct_hook = NULL;
                if (ct_hook)
                        ct_verdict = ct_hook->update(entry->state.net, entry->skb);
                rcu_read_unlock();

which defers this to the clash resolution logic.
The ct_hook->update infra predates this, I'm not sure we need
it anymore.