linux-kernel - Re: [PATCH ghak10 v5 1/2] audit: Add functions to log time adjustments

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Message-ID: <CAFqZXNsADjmP--Gy20nkF3NjADpAT+7JAWa2raEhQMGfhoaTvQ@mail.gmail.com>
Date:   Mon, 17 Sep 2018 14:32:46 +0200
From:   Ondrej Mosnacek <omosnace@...hat.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Steve Grubb <sgrubb@...hat.com>,
        Miroslav Lichvar <mlichvar@...hat.com>,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        Paul Moore <paul@...l-moore.com>,
        John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH ghak10 v5 1/2] audit: Add functions to log time adjustments

On Thu, Sep 13, 2018 at 5:19 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> On 2018-09-13 15:59, Ondrej Mosnacek wrote:
> > On Mon, Aug 27, 2018 at 6:38 PM Steve Grubb <sgrubb@...hat.com> wrote:
> > > On Monday, August 27, 2018 5:13:17 AM EDT Ondrej Mosnacek wrote:
> > > > On Mon, Aug 27, 2018 at 9:50 AM Miroslav Lichvar <mlichvar@...hat.com>
> > > wrote:
> > > > > On Fri, Aug 24, 2018 at 02:00:00PM +0200, Ondrej Mosnacek wrote:
> > > > > > This patch adds two auxiliary record types that will be used to
> > > > > > annotate
> > > > > > the adjtimex SYSCALL records with the NTP/timekeeping values that have
> > > > > > been changed.
> > > > >
> > > > > It seems the "adjust" function intentionally logs also calls/modes
> > > > > that don't actually change anything. Can you please explain it a bit
> > > > > in the message?
> > > > >
> > > > > NTP/PTP daemons typically don't read the adjtimex values in a normal
> > > > > operation and overwrite them on each update, even if they don't
> > > > > change. If the audit function checked that oldval != newval, the
> > > > > number of messages would be reduced and it might be easier to follow.
> > > >
> > > > We actually want to log any attempt to change a value, as even an
> > > > intention to set/change something could be a hint that the process is
> > > > trying to do something bad (see discussion at [1]).
> > >
> > > One of the problems is that these applications can flood the logs very
> > > quickly. An attempt to change is not needed unless it fails for permissions
> > > reasons. So, limiting to actual changes is probably a good thing.
> >
> > Well, Richard seemed to "violently" agree with the opposite, so now I
> > don't know which way to go... Paul, you are the official tie-breaker
> > here, which do you prefer?
>
> The circumstances have changed with new information being added.  I
> recall violently agreeing several iterations ago with your previous
> assessment, which has also changed with this new information.  I'd agree
> with Steve that a flood of information about something that did not
> change value could hide important information.

OK, understood.

> (BTW: The expression "to violoently agree with" is generally used in a
> situation where two parties appear to have been arguing two different
> sides of an issue and then realize they have much more in common than
> initially apparent.)

I see, thanks for the explanation!  I didn't know that expression
before, so I think I took it a bit too literally :)

>
> > > -Steve
> > >
> > > > There are valid
> > > > arguments both for and against this choice, but we have to pick one in
> > > > the end... Anyway, I should explain the reasoning in the commit
> > > > message better, right now it just states the fact without explanation
> > > > (in the second patch), thank you for pointing my attention to it.
> > > >
> > > > [1] https://www.redhat.com/archives/linux-audit/2018-July/msg00061.html
> > > >
> > > > --
> > > > Ondrej Mosnacek <omosnace at redhat dot com>
> >
> > Ondrej Mosnacek <omosnace at redhat dot com>
>
> - RGB
>
> --
> Richard Guy Briggs <rgb@...hat.com>
> 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

--
Ondrej Mosnacek <omosnace at redhat dot com>Associate Software
Engineer, Security Technologies
Red Hat, Inc.