netdev - Re: [PATCH net-next] netfilter: conntrack: avoid sending RST to reply out-of-window skb

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Message-ID: <20240308224657.GO4420@breakpoint.cc>
Date: Fri, 8 Mar 2024 23:46:57 +0100
From: Florian Westphal <fw@...len.de>
To: Jason Xing <kerneljasonxing@...il.com>
Cc: Florian Westphal <fw@...len.de>, edumazet@...gle.com,
	pablo@...filter.org, kadlec@...filter.org, kuba@...nel.org,
	pabeni@...hat.com, davem@...emloft.net,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next] netfilter: conntrack: avoid sending RST to
 reply out-of-window skb

Jason Xing <kerneljasonxing@...il.com> wrote:
> > connection.  Feel free to send patches that replace drop with -accept
> > where possible/where it makes sense, but I don't think the
> > TCP_CONNTRACK_SYN_SENT one can reasonably be avoided.
> 
> Oh, are you suggesting replacing NF_DROP with -NF_ACCEPT in
> nf_conntrack_dccp_packet()?

It would be more consistent with what tcp and sctp trackers are
doing, but this should not matter in practice (the packet is malformed).

> > +       case NFCT_TCP_INVALID: {
> > +               verdict = -NF_ACCEPT;
> > +               if (ct->status & IPS_NAT_MASK)
> > +                       res = NF_DROP; /* skb would miss nat transformation */
> 
> Above line, I guess, should be 'verdict = NF_DROP'?

Yes.

> Great! I think your draft patch makes sense really, which takes NAT
> into consideration.

You could submit this officially and we could give it a try and see if
anyone complains down the road.