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

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Message-ID: <CAL+tcoDv_tOAdjwpCCuBkgSCAn4rj4wnTWTB17DY0RpXnQ=p5w@mail.gmail.com>
Date: Sat, 9 Mar 2024 08:37:59 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Florian Westphal <fw@...len.de>
Cc: 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

On Sat, Mar 9, 2024 at 6:47 AM Florian Westphal <fw@...len.de> wrote:
>
> 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).

Okay, I will take some time to check the sctp part. BTW, just like one
of previous emails said, I noticed there are two points in DCCP part
which is not consistent with TCP part, so I submitted one simple patch
[1] to do it.

[1]: https://lore.kernel.org/all/20240308092915.9751-1-kerneljasonxing@gmail.com/

>
> > > +       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.

Great :)

Thanks,
Jason