Linux audit performance impact

[Richard Guy Briggs]

On 15/01/29, Viswanath, Logeswari P (MCOU OSTL) wrote:
> Please read my question as “Is there any option to configure kaudit
> not to log audit records to syslog? when auditd not running.”

Yeah, remove audit=1 from the kernel command line, or set audit=0 in its
place.  This will stop all but AVCs and if auditd has ever run since
boot.  If audit=0 is on the kernel boot line, it will be impossible to
run auditd.

There is a feature request that is likely coming soon that could be
useful:

https://bugzilla.redhat.com/show_bug.cgi?id=1160046
"If no audit daemon is running, but an audit multicast subscriber is
around, then the kernel shouldn't forward audit data to kmsg"

> From: Viswanath, Logeswari P (MCOU OSTL)
> Sent: Thursday, January 29, 2015 11:49 AM
> To: 'Satish Chandra Kilaru'; Steve Grubb
> Cc: linux-audit at redhat.com
> Subject: RE: Linux audit performance impact
> 
> Is there any option to configure kaudit not to log audit records to syslog when auditd is running?
> This way we can assess the impact of enabling audit without involving disk I/o overhead.
> 
> From: Satish Chandra Kilaru [mailto:iam.kilaru at gmail.com]
> Sent: Thursday, January 29, 2015 9:12 AM
> To: Steve Grubb
> Cc: linux-audit at redhat.com<mailto:linux-audit at redhat.com>; Viswanath, Logeswari P (MCOU OSTL)
> Subject: Re: Linux audit performance impact
> 
> I agree with you... but writing to disk can trigger further events leading spiralling of events...
> I brought down my server few times with stupid rules...
> 
> On Wed, Jan 28, 2015 at 10:39 PM, Steve Grubb <sgrubb at redhat.com<mailto:sgrubb at redhat.com>> wrote:
> On Wednesday, January 28, 2015 10:18:47 AM Satish Chandra Kilaru wrote:
> > Write your own program to receive audit events directly without using
> > auditd...
> > That should be faster ....
> > Auditd will log the events to disk causing more I/o than u need...
> 
> But even that is configurable in many ways. You can decide if you want logging
> to disk or not and what kind of assurance that it made it to disk and the
> priority of that audit daemon. Then you also have all the normal tuning knobs
> for disk throughput that you would use for any disk performance critical
> system.
> 
> -Steve
> 
> > On Wednesday, January 28, 2015, Viswanath, Logeswari P (MCOU OSTL) <
> >
> > logeswari.pv at hp.com<mailto:logeswari.pv at hp.com>> wrote:
> > >  Hi Steve,
> > >
> > > I am Logeswari working for HP.
> > >
> > >
> > >
> > > We want to know audit performance impact on RHEL and Suse linux to help us
> > > evaluate linux audit as data source for our host based IDS.
> > >
> > > When we ran our own performance test with a test audispd plugin, we found
> > > if a system can perform 200000 open/close system calls per second without
> > > auditing, system can perform only 3000 open/close system calls auditing is
> > > enabled for open/close system call which is a HUGE impact on the system
> > > performance. It would be great if anyone can help us answering the
> > > following questions.
> > >
> > >
> > >
> > > 1)      Is this performance impact expected? If yes, what is the reason
> > > behind it and can we fix it?
> > >
> > > 2)      Have anyone done any benchmarking for performance impact? If yes,
> > > can you please share the numbers and also the steps/programs used the run
> > > the same.
> > >
> > > 3)      Help us validating the performance test we have done in our test
> > > setup using the steps mentioned along with the results attached.
> > >
> > >
> > >
> > > Attached test program (loader.c) to invoke open and close system calls.
> > >
> > > Attached idskerndsp is the audispd plugin program.
> > >
> > > We used time command to determine how much time the system took to
> > > complete 50000 open/close system calls without (results attached
> > > Without-auditing) and with auditing enabled on the system
> > > (With-auditing-NOLOG-audispd-plugin and With-auditing-RAW)
> > >
> > >
> > >
> > > System details:
> > >
> > >
> > >
> > > 1 CPU machine
> > >
> > >
> > >
> > > *OS Version*
> > >
> > > RHEL 6.5
> > >
> > >
> > >
> > > *Kernel Version*
> > >
> > > uname –r
> > >
> > > 2.6.32-431.el6.x86_64
> > >
> > >
> > >
> > > Note: auditd was occupying 35% of CPU and was sleeping for most of the
> > > time whereas kauditd was occupying 20% of the CPU.
> > >
> > >
> > >
> > > Thanks & Regards,
> > >
> > > Logeswari.
> 
> 
> 
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- RGB

--
Richard Guy Briggs <rbriggs at redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
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