From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0AEF5C77B6F for ; Tue, 11 Apr 2023 12:36:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229598AbjDKMgI (ORCPT ); Tue, 11 Apr 2023 08:36:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229581AbjDKMgH (ORCPT ); Tue, 11 Apr 2023 08:36:07 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A242A30FA for ; Tue, 11 Apr 2023 05:36:06 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1pmDEC-0001cw-Pz; Tue, 11 Apr 2023 14:36:04 +0200 Date: Tue, 11 Apr 2023 14:36:04 +0200 From: Florian Westphal To: Pablo Neira Ayuso Cc: Florian Westphal , Jeremy Sowden , Netfilter Devel Subject: Re: [PATCH nftables 8/8] test: py: add tests for shifted nat port-ranges Message-ID: <20230411123604.GF21051@breakpoint.cc> References: <20230305101418.2233910-1-jeremy@azazel.net> <20230305101418.2233910-9-jeremy@azazel.net> <20230324225904.GB17250@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Pablo Neira Ayuso wrote: Circling back to this. > On Fri, Mar 24, 2023 at 11:59:04PM +0100, Florian Westphal wrote: > > Jeremy Sowden wrote: > > > +ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to 192.168.127.1:5900-5910/55900;ok > > > +ip6 daddr 10::1 tcp dport 55900-55910 dnat ip6 to [::c0:a8:7f:1]:5900-5910/55900;ok > > > > This syntax is horrible (yes, I know, xtables fault). > > > > Do you think this series could be changed to grab the offset register from the > > left edge of the range rather than requiring the user to specify it a > > second time? Something like: > > > > ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to 192.168.127.1:5900-5910 > > > > I'm open to other suggestions of course. > > To allow to mix this with maps, I think the best approach is to add a > new flag (port-shift) and then allow the user to specify the > port-shift 'delta'. > > ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to ip saddr map { \ > 192.168.127.0-129.168.127.128 : 1.2.3.4 . -55000 } port-shift > > where -55000 means, subtract -55000 to the tcp dport in the packet, it > is an incremental update. > > This requires a kernel patch to add the new port-shift flag. Where is this new port-shift flag needed? NAT engine? I'm a bit confused, are you proposing new/different syntax for Jeremys kernel-patchset or something else? AFAICS, for what you want do to, Jeremys kernel patches should already work as-is? Just to be clear again, I have no objects to the kernel patches that Jeremy proposed. I just dislike the iptables-inspired userspace syntax with a need to explicitly state the left edge of the range. > It should be possible to add a new netlink attribute > > NFTA_NAT_REG_PROTO_SHIFT > > which allows for -2^16 .. +2^16 to express the (positive/negative) > delta offset. Isn't that essentially what Jeremys patchset is already doing, i.e. adding a new register to store the offset? You can't use an immediate, else maps with different deltas don't work. > Parser would need to be taught to deal with negative and positive > offset, we probably need a new special type for named maps too > (port-shift). You mean a pseudotype to work with 'typeof'? We alreay do this for verdicts so this should work.