Date: Sun, 8 Sep 2013 17:54:35 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Steve Grubb <sgrubb@redhat.com>
Cc: linux-audit@redhat.com, Richard Guy Briggs <rgb@redhat.com>,
        linux-kernel@vger.kernel.org
Subject: Re: audit looks unmaintained? [was: Re: [PATCH 11/12] pid: rewrite
	task helper functions avoiding task->pid and task->tgid]
Message-ID: <20130908155435.GC4663@redhat.com>
References: <cover.1377032086.git.rgb@redhat.com> <20130827171134.GB29147@redhat.com> <20130830190646.GA30331@madcap2.tricolour.ca> <3996102.evTQ9SbNnV@x2>
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Sorry for delay, vacation.

First of all, I do not pretend I understand this code. This was mostly
the question, and in fact I mostly asked about audit_bprm() in 0/1.

However,

On 08/30, Steve Grubb wrote:
> On Friday, August 30, 2013 03:06:46 PM Richard Guy Briggs wrote:
> > On Tue, Aug 27, 2013 at 07:11:34PM +0200, Oleg Nesterov wrote:
> > > Btw. audit looks unmaintained... if you are going to take care of
> > > this code, perhaps you can look at
> > >
> > > 	http://marc.info/?l=linux-kernel&m=137589907108485
> > > 	http://marc.info/?l=linux-kernel&m=137590271809664
>
> You don't want to clear the TIF audit flag when context == NULL. What that will
> do is make a bunch of inauditable processes. There are times when audit is
> disabled and then re-enabled later. If the flag gets cleared, then a task's
> syscall will never enter the auditing framework from kernel/entry_64.S.
>
> That flag is 0 when auditing has never ever been enabled. If auditing is
> enabled, it should always be a 1 unless the task filter has determined that
> this process should not be audited ever. In practice, this is almost never
> used. But ensuring the TIF_SYSCALL_AUDIT set to 1 on all processes is why we
> have the boot argument. Not setting audit=1 on the boot arguments means that
> any process running before the audit daemon enables auditing can never ever be
> audited because the only place its set is when processes are cloned.

Then why audit_alloc() doesn't set TIF_SYSCALL_AUDIT unconditionally?

And I do not understand "when context == NULL" above. Say, audit_syscall_entry()
does nothing if !audit_context, and nobody except copy_process() does
audit_alloc(). So why do we need to trigger the audit's paths if it is NULL?

> Hope this clears up the use. NAK to the patch, it'll break auditing.

Not really, but thanks for your reply anyway.

Oleg.

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