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 3B8A5C31E5B for ; Mon, 17 Jun 2019 18:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 197CA2084D for ; Mon, 17 Jun 2019 18:28:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726443AbfFQS2s (ORCPT ); Mon, 17 Jun 2019 14:28:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43002 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725764AbfFQS2r (ORCPT ); Mon, 17 Jun 2019 14:28:47 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6F2EE307D90E; Mon, 17 Jun 2019 18:28:39 +0000 (UTC) Received: from localhost (ovpn-112-18.ams2.redhat.com [10.36.112.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C54E41001E86; Mon, 17 Jun 2019 18:28:34 +0000 (UTC) Date: Mon, 17 Jun 2019 20:28:30 +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 1/8] ipv4/fib_frontend: Rename ip_valid_fib_dump_req, provide non-strict version Message-ID: <20190617202830.3dd92d46@redhat.com> In-Reply-To: <43a9b0c7-27b4-733c-d3f2-60ad894e8aeb@gmail.com> References: <4dfbaf6a-5cff-13ea-341e-2b1f91c25d04@gmail.com> <20190615051342.7e32c2bb@redhat.com> <20190615052705.66f3fe62@redhat.com> <20190616220417.573be9a6@redhat.com> <20190617161333.29cab4d7@redhat.com> <43a9b0c7-27b4-733c-d3f2-60ad894e8aeb@gmail.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 17 Jun 2019 18:28:47 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 17 Jun 2019 11:06:51 -0600 David Ahern wrote: > On 6/17/19 8:13 AM, Stefano Brivio wrote: > >> > >> With strict checking (5.0 and forward): > >> - RTM_F_CLONED NOT set means dump only FIB entries > >> - RTM_F_CLONED set means dump only exceptions > > > > Okay. Should we really ignore the RFC and NLM_F_MATCH though? If we add > > field(s) to the filter, it comes almost for free, something like: > > > > if (nlh->nlmsg_flags & NLM_F_MATCH) > > filter->dump_exceptions = rtm->rtm_flags & RTM_F_CLONED; > > > > instead of: > > > > filter->dump_exceptions = rtm->rtm_flags & RTM_F_CLONED; > > This is where you keep losing me. iproute2 has always set NLM_F_MATCH on > dump requests, so that flag can not be used as a discriminator here. iproute2 yes, but some other users (I'm not aware of any so I have no examples) might *very* vaguely follow the RFC and expect consistent results. That was my only point here. Most likely just a theoretical one. > > > >> Without strict checking (old iproute2 on any kernel): > >> - dump all, userspace has to sort > >> > >> Kernel side this can be handled with new field, dump_exceptions, in the > >> filter that defaults to true and then is reset in the strict path if the > >> flag is not set. > > > > I guess we need to add two fields, we'll need a 'dump_routes' too. > > > > Otherwise, the dump functions can't distinguish between the three cases > > ('no strict checking', 'strict checking and RTM_F_CLONED', 'strict > > checking and no RTM_F_CLONED'). How would you do this with a single > > additional field? > > > > sure, separate fields are needed for the pre-strict mode use case. Well, they are needed, in general. They both start as true, non-strict mode doesn't clear them, strict mode clears one. That's how I would do it. > So, I take it we are converging on this: > > 1. non-strict mode, dump both (FIB entries and exceptions). Userspace > has to filter. This is the legacy behavior you are trying to restore. > > 2. strict mode: > a. dump only FIB entries if RTM_F_CLONED is not set > b. dump only exception entries if RTM_F_CLONED is set > > Agreed? Agreed in general, maybe let me know what you think about the NLM_F_MATCH point above though. -- Stefano