From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH v6 -next 2/4] netfilter: nftables: add connlabel set support Date: Mon, 25 Apr 2016 18:05:41 +0100 Message-ID: <20160425170541.GC9987@macbook.localdomain> References: <1461249284-12114-1-git-send-email-fw@strlen.de> <1461249284-12114-3-git-send-email-fw@strlen.de> <20160425103522.GB29560@macbook.localdomain> <20160425105909.GC28797@breakpoint.cc> <20160425111638.GB30849@macbook.localdomain> <20160425115622.GD28797@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org To: Florian Westphal Return-path: Received: from stinky.trash.net ([213.144.137.162]:56660 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754456AbcDYRFp (ORCPT ); Mon, 25 Apr 2016 13:05:45 -0400 Content-Disposition: inline In-Reply-To: <20160425115622.GD28797@breakpoint.cc> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On 25.04, Florian Westphal wrote: > Patrick McHardy wrote: > > > The alternative to internally handling it would be to some propagating > > validation to immediates / sets which invoke the actual user of the data. > > So in the case of helpers, we could replace the name by references to > > the helper structures and reverse this during dumping. > > > > Regarding connlabels this doesn't really apply though. We expect userspace > > to create a reasonable ruleset and anything that does not cause critical > > errors is validated in userspace. > > Yes. So we have three choices here (pseudo-code) > > memcpy(ct->labels, regs->data[priv->sreg], sizeof(reg)); > vs. > set_bit(priv->imm, ct->labels); > > The latter is what the iptables module does, I do not mind if we > go for #1 (treat the label area just like an 128bit register and > replace it completely with whatever is in the source register). > > My only problem is that Pablo suggested #2 whereas you recommend #1. > > I don't want to resubmit until there is consensus as to what the > preferred solution is. > > We could go for a 3rd alternative, namely: > > u16 bit = regs->data[priv->sreg]; > set_bit(bit, ct->labels); > > i.e. have userspace place the _bit_ that we want to set in the > source register. > > If we go for sreg that would be my favored solution. > > The only drawback vs #1 is that get and set work differently > (get places all labels into dreg, set expects bit to set). That seems like a problem. I agree that #3 would generally be fine, but we should also really have "ct labels set ct labels" not change the labels, that would be highly counterintuitive.