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=-1.0 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 138C5C4321D for ; Fri, 24 Aug 2018 14:56:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3045208B7 for ; Fri, 24 Aug 2018 14:56:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3045208B7 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 S1727479AbeHXSbX (ORCPT ); Fri, 24 Aug 2018 14:31:23 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:35988 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726387AbeHXSbX (ORCPT ); Fri, 24 Aug 2018 14:31:23 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2789F40216EC; Fri, 24 Aug 2018 14:56:23 +0000 (UTC) Received: from x2.localnet (ovpn-121-58.rdu2.redhat.com [10.10.121.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 386F91007278; Fri, 24 Aug 2018 14:56:19 +0000 (UTC) From: Steve Grubb To: Paul Moore Cc: mlichvar@redhat.com, omosnace@redhat.com, tglx@linutronix.de, linux-audit@redhat.com, rgb@redhat.com, john.stultz@linaro.org, sboyd@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH ghak10 v4 0/2] audit: Log modifying adjtimex(2) calls Date: Fri, 24 Aug 2018 10:56:19 -0400 Message-ID: <2148764.ODNUjEgRWb@x2> Organization: Red Hat In-Reply-To: References: <20180820123818.27547-1-omosnace@redhat.com> <20180821072114.GC23069@localhost> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 24 Aug 2018 14:56:23 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 24 Aug 2018 14:56:23 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'sgrubb@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -Steve