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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE440C4363A for ; Wed, 21 Oct 2020 10:43:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50F4C20795 for ; Wed, 21 Oct 2020 10:43:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410333AbgJUKn1 (ORCPT ); Wed, 21 Oct 2020 06:43:27 -0400 Received: from correo.us.es ([193.147.175.20]:35312 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2410312AbgJUKn0 (ORCPT ); Wed, 21 Oct 2020 06:43:26 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id DEF0CD2B841 for ; Wed, 21 Oct 2020 12:43:24 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id D036CFA52A for ; Wed, 21 Oct 2020 12:43:24 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id C599853893; Wed, 21 Oct 2020 12:43:24 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 739A4E150F; Wed, 21 Oct 2020 12:43:22 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Wed, 21 Oct 2020 12:43:22 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id 57A864301DE4; Wed, 21 Oct 2020 12:43:22 +0200 (CEST) Date: Wed, 21 Oct 2020 12:43:22 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Phil Sutter , Florian Westphal , netfilter-devel@vger.kernel.org Subject: Re: [net-next PATCH 0/2] netfilter: Improve inverted IP prefix matches Message-ID: <20201021104321.GA30742@salvia> References: <20201001165744.25466-1-phil@nwl.cc> <20201001222536.GB12773@breakpoint.cc> <20201002090033.GB1845@orbyte.nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201002090033.GB1845@orbyte.nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi Phil, On Fri, Oct 02, 2020 at 11:00:33AM +0200, Phil Sutter wrote: > Hi Florian, > > On Fri, Oct 02, 2020 at 12:25:36AM +0200, Florian Westphal wrote: > > Phil Sutter wrote: > > > The following two patches improve packet throughput in a test setup > > > sending UDP packets (using iperf3) between two netns. The ruleset used > > > on receiver side is like this: > > > > > > | *filter > > > | :test - [0:0] > > > | -A INPUT -j test > > > | -A INPUT -j ACCEPT > > > | -A test ! -s 10.0.0.0/10 -j DROP # this line repeats 10000 times > > > | COMMIT > > > > > > These are the generated VM instructions for each rule: > > > > > > | [ payload load 4b @ network header + 12 => reg 1 ] > > > | [ bitwise reg 1 = (reg=1 & 0x0000c0ff ) ^ 0x00000000 ] > > > > Not related to this patch, but we should avoid the bitop if the > > netmask is divisble by 8 (can adjust the cmp -- adjusting the > > payload expr is probably not worth it). > > See the patch I just sent to this list. I adjusted both - it simply > didn't appear to me that I could get by with reducing the cmp expression > size only. The upside though is that detecting the prefix match based on > payload expression length is quick and easy. > > Someone will have to adjust nft tool, though. ;) > > > > | [ cmp eq reg 1 0x0000000a ] > > > | [ counter pkts 0 bytes 0 ] > > > > Out of curiosity, does omitting 'counter' help? > > > > nft counter is rather expensive due to bh disable, > > iptables does it once at the evaluation loop only. > > I changed the test to create the base ruleset using iptables-nft-restore > just as before, but create the rules in 'test' chain like so: > > | nft add rule filter test ip saddr != 10.0.0.0/10 drop > > The VM code is as expected: > > | [ payload load 4b @ network header + 12 => reg 1 ] > | [ bitwise reg 1 = (reg=1 & 0x0000c0ff ) ^ 0x00000000 ] > | [ cmp eq reg 1 0x0000000a ] > | [ immediate reg 0 drop ] > > Performance is ~7000pkt/s. So while it's faster than iptables-nft, it's > still quite a bit slower than legacy iptables despite the skipped > counters. iptables is optimized for matching on input/output device name and IPv4 address + mask (see ip_packet_match()) for historical reasons, iptables does not use a match for this since the beginning. One possibility (in the short-term) is to add an internal kernel expression to achieve the same behaviour. The kernel needs to detects for: payload (nh, offset to ip saddr or ip daddr or ip protocol) + cmp payload (nh, offset to ip saddr or ip daddr) + bitwise + cmp meta (iifname or oifname) + bitwise + cmp meta (iifname or oifname) + cmp at the very beginning of the rule. and squash these expressions into the "built-in" iptables match expression which emulates ip_packet_match(). Not nice, but if microbenchmarks using thousand of rules really matter (this is worst case O(n) linear list evaluation...) then it might make sense to explore this.