linux-kernel - Re: [PATCH] audit: set TIF_AUDIT_SYSCALL only if audit filter has been populated

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Date:   Wed, 7 Mar 2018 17:48:59 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Andy Lutomirski <luto@...nel.org>
cc:     Oleg Nesterov <oleg@...hat.com>, Paul Moore <paul@...l-moore.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] audit: set TIF_AUDIT_SYSCALL only if audit filter has
 been populated

On Wed, 7 Mar 2018, Andy Lutomirski wrote:

> Wow, this was a long time ago.  

Oh yeah; but it now resurfaced on our side, as we are of course receiving 
a lot of requests with respect to making syscall performance great again 
:)

> From memory and a bit of email diving, there are two reasons.
> 
> 1. The probably was partially solved (by Oleg, IIRC) by making auditctl 
>    -a task,never cause newly spawned tasks to not suck.  Yes, it's a 
>    very partial solution.  After considerable nagging, I got Fedora to 
>    default to -a task,never.

Hm, right; that's a bit inconvenient, because it takes each and every 
vendor having to realize this option, and put it in. Making kernel do the 
right thing automatically sounds like a better option to me.

> 2. This patch, as is, may be a bit problematic.  In particular, if one 
>    task changes the audit rules while another task is in the middle of 
>    the syscall, then it's too late to audit that syscall correctly.  
>    This could be seen as a bug or it could be seen as being just fine.

I don't think this should be a problem, given the fact that the whole 
timing/ordering is not predictable anyway due to scheduling.

Paul, what do you think?

Thanks,

-- 
Jiri Kosina
SUSE Labs