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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 9A317C31E44 for ; Sat, 15 Jun 2019 03:23:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 790C720850 for ; Sat, 15 Jun 2019 03:23:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726392AbfFODXj (ORCPT ); Fri, 14 Jun 2019 23:23:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45396 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726046AbfFODXj (ORCPT ); Fri, 14 Jun 2019 23:23:39 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D7CFA8553D; Sat, 15 Jun 2019 03:23:38 +0000 (UTC) Received: from localhost (ovpn-112-18.ams2.redhat.com [10.36.112.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4F52B5C239; Sat, 15 Jun 2019 03:23:36 +0000 (UTC) Date: Sat, 15 Jun 2019 05:23:32 +0200 From: Stefano Brivio To: David Ahern Cc: David Miller , Martin KaFai Lau , Jianlin Shi , Wei Wang , Eric Dumazet , Matti Vaittinen , netdev@vger.kernel.org Subject: Re: [PATCH net v4 2/8] ipv4: Honour NLM_F_MATCH, make semantics of NETLINK_GET_STRICT_CHK consistent Message-ID: <20190615052332.16628b2c@redhat.com> In-Reply-To: <9abeefb6-81a7-dc0a-30f4-f15ccf4edc86@gmail.com> References: <58865c4c143d0da40cd417b5b87b49d292d8129d.1560561432.git.sbrivio@redhat.com> <9abeefb6-81a7-dc0a-30f4-f15ccf4edc86@gmail.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Sat, 15 Jun 2019 03:23:38 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, 14 Jun 2019 21:13:38 -0600 David Ahern wrote: > On 6/14/19 7:32 PM, Stefano Brivio wrote: > > Socket option NETLINK_GET_STRICT_CHK, quoting from commit 89d35528d17d > > ("netlink: Add new socket option to enable strict checking on dumps"), > > is used to "request strict checking of headers and attributes on dump > > requests". > > > > If some attributes are set (including flags), setting this option causes > > dump functions to filter results according to these attributes, via the > > filter_set flag. However, if strict checking is requested, this should > > imply that we also filter results based on flags that are *not* set. > > I don't agree with that comment. If a request does not specify a bit or > specify an attribute on the request, it is a wildcard in the sense of > nothing to be considered when matching records to be returned. This is what I had in v1. Then: On Thu, 6 Jun 2019 16:47:00 -0600 David Ahern wrote: > That's the use case I was targeting: > 1. fib dumps - RTM_F_CLONED not set > 2. exception dump - RTM_F_CLONED set On Mon, 10 Jun 2019 15:38:06 -0600 David Ahern wrote: > By that I mean without the CLONED flag, no exceptions are returned > (default FIB dump). With the CLONED flag only exceptions are returned. and this looks to me like a sensible way (if strict checking is requested, or if NLM_F_MATCH is passed) to filter the results. > > This is currently not the case, at least for IPv4 FIB dumps: if the > > RTM_F_CLONED flag is not set, and strict checking is required, we should > > not return routes with the RTM_F_CLONED flag set. > > IPv4 currently ignores the CLONED flag and just returns - regardless of > whether strict checking is enabled. This is the original short cut added > many years ago. Sure, and I'm removing that, because there's no way to fetch cached routes otherwise. > > Set the filter_set flag whenever strict checking is requested, limiting > > the scope to IPv4 FIB dumps for the moment being, as other users of the > > flag might not present this inconsistency. > > > > Note that this partially duplicates the semantics of NLM_F_MATCH as > > described by RFC 3549, par. 3.1.1. Instead of setting a filter based on > > the size of the netlink message, properly support NLM_F_MATCH, by > > setting a filter via ip_filter_fib_dump_req() and setting the filter_set > > flag. > > > > your commit description is very confusing given the end goal. can you > explain again? 1. we need a way to filter on cached routes 2. RTM_F_CLONED, by itself, doesn't specify a filter 3. how do we turn that into a filter? NLM_F_MATCH, says RFC 3549 4. but if strict checking is requested, you also turn some attributes and flags into filters -- so let's make that apply to RTM_F_CLONED too, I don't see any reason why that should be special -- Stefano