linux-kernel - Re: ntp audit spew.

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Message-ID: <2130348.JY4ctgmguH@x2>
Date:   Tue, 24 Sep 2019 09:19:23 -0400
From:   Steve Grubb <sgrubb@...hat.com>
To:     linux-audit@...hat.com
Cc:     Paul Moore <paul@...l-moore.com>,
        Dave Jones <davej@...emonkey.org.uk>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: ntp audit spew.

On Monday, September 23, 2019 12:14:14 PM EDT Paul Moore wrote:
> On Mon, Sep 23, 2019 at 11:50 AM Dave Jones <davej@...emonkey.org.uk> 
wrote:
> > I have some hosts that are constantly spewing audit messages like so:
> > 
> > [46897.591182] audit: type=1333 audit(1569250288.663:220): op=offset
> > old=2543677901372 new=2980866217213 [46897.591184] audit: type=1333
> > audit(1569250288.663:221): op=freq old=-2443166611284 new=-2436281764244
> > [48850.604005] audit: type=1333 audit(1569252241.675:222): op=offset
> > old=1850302393317 new=3190241577926 [48850.604008] audit: type=1333
> > audit(1569252241.675:223): op=freq old=-2436281764244 new=-2413071187316
> > [49926.567270] audit: type=1333 audit(1569253317.638:224): op=offset
> > old=2453141035832 new=2372389610455 [49926.567273] audit: type=1333
> > audit(1569253317.638:225): op=freq old=-2413071187316 new=-2403561671476
> > 
> > This gets emitted every time ntp makes an adjustment, which is apparently
> > very frequent on some hosts.
> > 
> > 
> > Audit isn't even enabled on these machines.
> > 
> > # auditctl -l
> > No rules
> 
> [NOTE: added linux-audit to the CC line]
> 
> There is an audit mailing list, please CC it when you have audit
> concerns/questions/etc.
> 
> What happens when you run 'auditctl -a never,task'? 

Actually, "-e 0" should turn it off. There is a general problem where systemd 
turns on auditing just because it can. The above rule just makes audit 
processes inauditable, but does not affect the kernel originating events.

-Steve

> That *should*
> silence those messages as the audit_ntp_log() function has the
> requisite audit_dummy_context() check.  FWIW, this is the distro
> default for many (most? all?) distros; for example, check
> /etc/audit/audit.rules on a stock Fedora system.  A more selective
> configuration could simply exclude the TIME_ADJNTPVAL record (type
> 1333) from the records that the kernel emits.
> 
> We could also add a audit_enabled check at the top of
> audit_ntp_log()/__audit_ntp_log(), but I imagine some of that depends
> on the various security requirements (they can be bizzare and I can't
> say I'm up to date on all those - Steve Grubb should be able to
> comment on that).