netdev - Re: [PATCH 1/1] netfilter: Add helper array register/unregister functions

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Date:	Wed, 20 Jul 2016 10:40:01 +0200
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Liping Zhang <zlpnobody@...il.com>
Cc:	fgao@...ai8.com, Patrick McHardy <kaber@...sh.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, gfree.wind@...il.com
Subject: Re: [PATCH 1/1] netfilter: Add helper array register/unregister
 functions

On Wed, Jul 20, 2016 at 08:51:17AM +0800, Liping Zhang wrote:
> 2016-07-18 11:39 GMT+08:00  <fgao@...ai8.com>:
> > From: Gao Feng <fgao@...ai8.com>
> >
> > Add nf_ct_helper_init, nf_conntrack_helpers_register/unregister
> > functions to enhance the conntrack helper codes.
> 
> I think this patch is breaking something ...
> 
> This irc:
> > -               if (ports[i] == IRC_PORT)
> > -                       sprintf(irc[i].name, "irc");
> > -               else
> > -                       sprintf(irc[i].name, "irc-%u", i);
> > -
> > -               ret = nf_conntrack_helper_register(&irc[i]);
> > +               nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc",
> > +                                 IRC_PORT, ports[i], &irc_exp_policy, 0, 0,
> > +                                 help, NULL, THIS_MODULE);
> > +       }
> 
> This sip:
> > -                       if (ports[i] == SIP_PORT)
> > -                               sprintf(sip[i][j].name, "sip");
> > -                       else
> > -                               sprintf(sip[i][j].name, "sip-%u", i);
> 
> And this tftp:
> > -                       if (ports[i] == TFTP_PORT)
> > -                               sprintf(tftp[i][j].name, "tftp");
> > -                       else
> > -                               sprintf(tftp[i][j].name, "tftp-%u", i);
> 
> For example, if the user install the nf_conntrack_tftp module an
> specify the ports to "69,10069",
> then the helper name is "tftp" and "tftp-1".
> 
> But apply this patch, the helper name will be changed to "tftp" and
> "tftp-10069", this may break the
> existing iptables rules which used the helper match or CT target.
>
> And this was already discussed  at
> https://patchwork.ozlabs.org/patch/622238/

Thanks for spotting this.

I'm going to collapse this patch that I'm attaching to Feng's work to
address this.

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