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_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 7649FC04ABB for ; Thu, 13 Sep 2018 14:08:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A94520854 for ; Thu, 13 Sep 2018 14:08:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A94520854 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730106AbeIMTRk (ORCPT ); Thu, 13 Sep 2018 15:17:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48580 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727566AbeIMTRk (ORCPT ); Thu, 13 Sep 2018 15:17:40 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7DD10317C40E; Thu, 13 Sep 2018 14:08:00 +0000 (UTC) Received: from x2.localnet (ovpn-122-199.rdu2.redhat.com [10.10.122.199]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F5735D6B5; Thu, 13 Sep 2018 14:07:55 +0000 (UTC) From: Steve Grubb To: Ondrej Mosnacek Cc: Paul Moore , Miroslav Lichvar , Thomas Gleixner , Linux-Audit Mailing List , Richard Guy Briggs , John Stultz , Stephen Boyd , Linux kernel mailing list Subject: Re: [RFC PATCH ghak10 v4 0/2] audit: Log modifying adjtimex(2) calls Date: Thu, 13 Sep 2018 10:07:54 -0400 Message-ID: <192111258.UpI01XQOzn@x2> Organization: Red Hat In-Reply-To: References: <20180820123818.27547-1-omosnace@redhat.com> <2148764.ODNUjEgRWb@x2> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 13 Sep 2018 14:08:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, September 13, 2018 9:58:32 AM EDT Ondrej Mosnacek wrote: > On Fri, Aug 24, 2018 at 4:56 PM Steve Grubb wrote: > > On Wednesday, August 22, 2018 5:27:17 PM EDT Paul Moore wrote: > > > On Tue, Aug 21, 2018 at 3:21 AM Miroslav Lichvar > > > > wrote: > > > > > On Mon, 20 Aug 2018, Ondrej Mosnacek wrote: > > > > > > @John or other timekeeping/NTP folks: We had a discussion on the > > > > > > audit > > > > > > ML on which of the internal timekeeping/NTP variables we should > > > > > > actually > > > > > > log changes for. We are only interested in variables that can > > > > > > (directly > > > > > > or indirectly) cause noticeable changes to the system clock, but > > > > > > since we > > > > > > have only limited understanding of the NTP code, we would like to > > > > > > ask > > > > > > you for advice on which variables are security relevant. > > > > > > > > I guess that mostly depends on whether you consider setting the clock > > > > to run faster or slower than real time to be an important event for > > > > the audit. > > > > > > > > > > - NTP value adjustments: > > > > > > - time_offset (probably important) > > > > > > > > This can adjust the clock by up to 0.5 seconds per call and also > > > > speed > > > > it up or slow down by up to about 0.05% (43 seconds per day). > > > > > > This seems worthwhile. > > > > > > > > > - time_freq (maybe not important?) > > > > > > > > This can speed up or slow down by up to about 0.05%. > > > > > > This too. > > > > > > > > > - time_status (likely important, can cause leap second injection) > > > > > > > > Yes, it can insert/delete leap seconds and it also enables/disables > > > > synchronization of the hardware real-time clock. > > > > > > This one as well. > > > > > > > > > - time_maxerror (maybe not important?) > > > > > > - time_esterror (maybe not important?) > > > > > > > > These two change the error estimates that are reported to > > > > applications > > > > using ntp_gettime()/adjtimex(). If an application was periodically > > > > checking that the clock is synchronized with some specified accuracy > > > > and setting the maxerror to a larger value would cause the > > > > application to abort, would it be an important event in the audit? > > > > > > Since these don't really affect the time, just the expected error, I'm > > > not sure this is important. > > > > I don't think so. > > Sorry, just to make sure I understand it right - do you (also) not > think it is important or do you not think it is not important? :) I do not think its important to record the errors since the exit code tells us there's a problem. IOW, I'm agreeing with Paul. -Steve