linux-kernel - Re: [PATCH v2] io_uring,audit: don't log IORING_OP

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Date:   Thu, 09 Feb 2023 17:54:24 -0500
From:   Steve Grubb <sgrubb@...hat.com>
To:     Richard Guy Briggs <rgb@...hat.com>,
        Paul Moore <paul@...l-moore.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, io-uring@...r.kernel.org,
        Eric Paris <eparis@...isplace.org>,
        Christian Brauner <brauner@...nel.org>,
        Stefan Roesch <shr@...com>
Subject: Re: [PATCH v2] io_uring,audit: don't log IORING_OP_MADVISE

On Thursday, February 9, 2023 5:37:22 PM EST Paul Moore wrote:
> On Thu, Feb 9, 2023 at 4:53 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > On 2023-02-01 16:18, Paul Moore wrote:
> > > On Wed, Feb 1, 2023 at 3:34 PM Richard Guy Briggs <rgb@...hat.com> 
wrote:
> > > > fadvise and madvise both provide hints for caching or access pattern
> > > > for file and memory respectively.  Skip them.
> > > 
> > > You forgot to update the first sentence in the commit description :/
> > 
> > I didn't forget.  I updated that sentence to reflect the fact that the
> > two should be treated similarly rather than differently.
> 
> Ooookay.  Can we at least agree that the commit description should be
> rephrased to make it clear that the patch only adjusts madvise?  Right
> now I read the commit description and it sounds like you are adjusting
> the behavior for both fadvise and madvise in this patch, which is not
> true.
> 
> > > I'm still looking for some type of statement that you've done some
> > > homework on the IORING_OP_MADVISE case to ensure that it doesn't end
> > > up calling into the LSM, see my previous emails on this.  I need more
> > > than "Steve told me to do this".
> > > 
> > > I basically just want to see that some care and thought has gone into
> > > this patch to verify it is correct and good.
> > 
> > Steve suggested I look into a number of iouring ops.  I looked at the
> > description code and agreed that it wasn't necessary to audit madvise.
> > The rationale for fadvise was detemined to have been conflated with
> > fallocate and subsequently dropped.  Steve also suggested a number of
> > others and after investigation I decided that their current state was
> > correct.  *getxattr you've advised against, so it was dropped.  It
> > appears fewer modifications were necessary than originally suspected.
> 
> My concern is that three of the four changes you initially proposed
> were rejected, which gives me pause about the fourth.  You mention
> that based on your reading of madvise's description you feel auditing
> isn't necessary - and you may be right - but based on our experience
> so far with this patchset I would like to hear that you have properly
> investigated all of the madvise code paths, and I would like that in
> the commit description.

I think you're being unnecessarily hard on this. Yes, the commit message 
might be touched up. But madvise is advisory in nature. It is not security 
relevant. And a grep through the security directory doesn't turn up any 
hooks.

-Steve