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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 969A1C43331 for ; Mon, 30 Mar 2020 15:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F18E20732 for ; Mon, 30 Mar 2020 15:24:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bvJPEj2g" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729057AbgC3PYJ (ORCPT ); Mon, 30 Mar 2020 11:24:09 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:57977 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728955AbgC3PYI (ORCPT ); Mon, 30 Mar 2020 11:24:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585581847; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=D5uFspd3/cIWYU7H3JtoXL8Mlj5rBTwKwCCQJPO8iZg=; b=bvJPEj2g2dIkdhNV+J6wWwtyLCAbTcEXIkPz0gvswjjSPfQKAHIzrujVbcSGHWsdtFq5mu EQj0RabGUvpTIlaxux7Hxq6vMTzJpkdhdyORip5PcmrX0F5owpVZ9e4yIsGRDexL35LqjK mExqJ5pLR4rcX3G1+gncUkcU15NDI/I= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-92-43WTi89VPVK6XSkd5tw5ow-1; Mon, 30 Mar 2020 11:24:03 -0400 X-MC-Unique: 43WTi89VPVK6XSkd5tw5ow-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 32077DB6E; Mon, 30 Mar 2020 15:24:01 +0000 (UTC) Received: from madcap2.tricolour.ca (unknown [10.10.110.46]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 19F5399DEC; Mon, 30 Mar 2020 15:23:49 +0000 (UTC) Date: Mon, 30 Mar 2020 11:23:47 -0400 From: Richard Guy Briggs To: Paul Moore Cc: Steve Grubb , linux-audit@redhat.com, nhorman@tuxdriver.com, linux-api@vger.kernel.org, containers@lists.linux-foundation.org, LKML , dhowells@redhat.com, netfilter-devel@vger.kernel.org, ebiederm@xmission.com, simo@redhat.com, netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, Eric Paris , mpatel@redhat.com, Serge Hallyn Subject: Re: [PATCH ghak90 V8 07/16] audit: add contid support for signalling the audit daemon Message-ID: <20200330152347.zjrcd6uuolfnq3fy@madcap2.tricolour.ca> References: <20200312202733.7kli64zsnqc4mrd2@madcap2.tricolour.ca> <20200313192306.wxey3wn2h4htpccm@madcap2.tricolour.ca> <20200318214154.ycxy5dl4pxno6fvi@madcap2.tricolour.ca> <20200319214759.qgxt2sfkmd6srdol@madcap2.tricolour.ca> <20200325122903.obkpyog7fjabzrpf@madcap2.tricolour.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-03-28 23:17, Paul Moore wrote: > On Wed, Mar 25, 2020 at 8:29 AM Richard Guy Briggs wrote: > > On 2020-03-20 17:56, Paul Moore wrote: > > > On Thu, Mar 19, 2020 at 5:48 PM Richard Guy Briggs wrote: > > > > On 2020-03-18 17:47, Paul Moore wrote: > > > > > On Wed, Mar 18, 2020 at 5:42 PM Richard Guy Briggs wrote: > > > > > > On 2020-03-18 17:01, Paul Moore wrote: > > > > > > > On Fri, Mar 13, 2020 at 3:23 PM Richard Guy Briggs wrote: > > > > > > > > On 2020-03-13 12:42, Paul Moore wrote: > > > > > > > > > > > > > > ... > > > > > > > > > > > > > > > > The thread has had a lot of starts/stops, so I may be repeating a > > > > > > > > > previous suggestion, but one idea would be to still emit a "death > > > > > > > > > record" when the final task in the audit container ID does die, but > > > > > > > > > block the particular audit container ID from reuse until it the > > > > > > > > > SIGNAL2 info has been reported. This gives us the timely ACID death > > > > > > > > > notification while still preventing confusion and ambiguity caused by > > > > > > > > > potentially reusing the ACID before the SIGNAL2 record has been sent; > > > > > > > > > there is a small nit about the ACID being present in the SIGNAL2 > > > > > > > > > *after* its death, but I think that can be easily explained and > > > > > > > > > understood by admins. > > > > > > > > > > > > > > > > Thinking quickly about possible technical solutions to this, maybe it > > > > > > > > makes sense to have two counters on a contobj so that we know when the > > > > > > > > last process in that container exits and can issue the death > > > > > > > > certificate, but we still block reuse of it until all further references > > > > > > > > to it have been resolved. This will likely also make it possible to > > > > > > > > report the full contid chain in SIGNAL2 records. This will eliminate > > > > > > > > some of the issues we are discussing with regards to passing a contobj > > > > > > > > vs a contid to the audit_log_contid function, but won't eliminate them > > > > > > > > all because there are still some contids that won't have an object > > > > > > > > associated with them to make it impossible to look them up in the > > > > > > > > contobj lists. > > > > > > > > > > > > > > I'm not sure you need a full second counter, I imagine a simple flag > > > > > > > would be okay. I think you just something to indicate that this ACID > > > > > > > object is marked as "dead" but it still being held for sanity reasons > > > > > > > and should not be reused. > > > > > > > > > > > > Ok, I see your point. This refcount can be changed to a flag easily > > > > > > enough without change to the api if we can be sure that more than one > > > > > > signal can't be delivered to the audit daemon *and* collected by sig2. > > > > > > I'll have a more careful look at the audit daemon code to see if I can > > > > > > determine this. > > > > > > > > > > Maybe I'm not understanding your concern, but this isn't really > > > > > different than any of the other things we track for the auditd signal > > > > > sender, right? If we are worried about multiple signals being sent > > > > > then it applies to everything, not just the audit container ID. > > > > > > > > Yes, you are right. In all other cases the information is simply > > > > overwritten. In the case of the audit container identifier any > > > > previous value is put before a new one is referenced, so only the last > > > > signal is kept. So, we only need a flag. Does a flag implemented with > > > > a rcu-protected refcount sound reasonable to you? > > > > > > Well, if I recall correctly you still need to fix the locking in this > > > patchset so until we see what that looks like it is hard to say for > > > certain. Just make sure that the flag is somehow protected from > > > races; it is probably a lot like the "valid" flags you sometimes see > > > with RCU protected lists. > > > > This is like looking for a needle in a haystack. Can you point me to > > some code that does "valid" flags with RCU protected lists. > > Sigh. Come on Richard, you've been playing in the kernel for some > time now. I can't think of one off the top of my head as I write > this, but there are several resources that deal with RCU protected > lists in the kernel, Google is your friend and Documentation/RCU is > your friend. Ok, I thought you were talking about a specific piece of code... > Spending time to learn how RCU works and how to use it properly is not > time wasted. It's a tricky thing to get right (I have to refresh my > memory on some of the more subtle details each time I write/review RCU > code), but it's very cool when done correctly. I review Documentation/RCU almost every time I work on RCU... > paul moore - RGB -- Richard Guy Briggs Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635