linux-kernel - Re: [PATCH] audit: always enable syscall auditing when supported and audit is enabled

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Date:   Mon, 28 Jan 2019 09:52:34 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@...ia.com>
Cc:     Paul Moore <pmoore@...hat.com>,
        "linux-audit@...hat.com" <linux-audit@...hat.com>,
        Richard Guy Briggs <rbriggs@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] audit: always enable syscall auditing when supported and
 audit is enabled

On Mon, Jan 28, 2019 at 9:36 AM Sverdlin, Alexander (Nokia - DE/Ulm)
<alexander.sverdlin@...ia.com> wrote:
> Hello Paul,
>
> On 28/01/2019 15:19, Paul Moore wrote:
> >>> time also enables syscall auditing; this patch simplifies the Kconfig
> >>> menus by removing the option to disable syscall auditing when audit
> >>> is selected and the target arch supports it.
> >>>
> >>> Signed-off-by: Paul Moore <pmoore@...hat.com>
> >> this patch is responsible for massive performance degradation for those
> >> who used only CONFIG_SECURITY_APPARMOR.
> >>
> >> And the numbers are, take the following test for instance:
> >>
> >> dd if=/dev/zero of=/dev/null count=2M
> >>
> >> ARM64:      500MB/s -> 350MB/s
> >> ARM:        400MB/s -> 300MB/s
> > Hi there.
> >
> > Out of curiosity, what kernel/distribution are you running, or is this
> > a custom kernel compile?  Can you also share the output of 'auditctl
>
> This test was carried out with Linux 4.9. Custom built.

I suspected that was the case, thanks.

> > -l' from your system?  The general approach taken by everyone to
> > turn-off the per-syscall audit overhead is to add the "-a never,task"
> > rule to their audit configuration:
> >
> >  # auditctl -a never,task
> >
> > If you are using Fedora/CentOS/RHEL, or a similarly configured system,
>
> This is an embedded distribution. We are not using auditctl or any other
> audit-related user-space packages.
>
> > you can find this configuration in the /etc/audit/audit.rules file (be
> > warned, that file is automatically generated based on
> > /etc/audit/rules.d).
>
> I suppose in this case rule list must be empty. Is there a way to check
> this without extra user-space packages?

Yes, unless you are loading rules through some other method I would
expect that your audit rule list is empty.

I'm not aware of any other tools besides auditctl to load audit rules
into the kernel, although I haven't ever had a need for another tool
so I haven't looked very hard.  If you didn't want to bring auditctl
into your distribution, I expect it would be a rather trivial task to
create a small tool to load a single "-a never,task" into the kernel.

-- 
paul moore
www.paul-moore.com