Date:   Fri, 10 Feb 2023 10:39:19 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Steve Grubb <sgrubb@...hat.com>,
        Richard Guy Briggs <rgb@...hat.com>,
        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 Thu, Feb 9, 2023 at 7:15 PM Jens Axboe <axboe@...nel.dk> wrote:
> On 2/9/23 3:54 PM, Steve Grubb wrote:
> > 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.
>
> Agree, it's getting a bit anal... FWIW, patch looks fine to me.

Call it whatever you want, but the details are often important at this
level of code, and when I see a patch author pushing back on verifying
that their patch is correct it makes me very skeptical.

I really would have preferred that you held off from merging this
until this was resolved and ACK'd ... oh well.

-- 
paul-moore.com

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