On 2020-12-07 16:13, Max Englander wrote:
> On Fri, Dec 4, 2020 at 3:41 PM Paul Moore <paul@paul-moore.com> wrote:
>
> > On Thu, Dec 3, 2020 at 9:47 PM Steve Grubb <sgrubb@redhat.com> wrote:
> > > On Thursday, December 3, 2020 9:16:52 PM EST Paul Moore wrote:
> > > > > > > Author:     Richard Guy Briggs <rgb@redhat.com>
> > > > > > > AuthorDate: 2014-11-17 15:51:01 -0500
> > > > > > > Commit:     Paul Moore <pmoore@redhat.com>
> > > > > > > CommitDate: 2014-11-17 16:53:51 -0500
> > > > > > > ("audit: convert status version to a feature bitmap")
> > > > > > > It was introduced specifically to enable distributions to
> > selectively
> > > > > > > backport features.  It was converted away from AUDIT_VERSION.
> > > > > > >
> > > > > > > There are other ways to detect the presence of
> > > > > > > backlog_wait_time_actual
> > > > > > > as I mentioned above.
> > > > > >
> > > > > > Let me be blunt - I honestly don't care what Steve's audit
> > userspace
> > > > > > does to detect this.  I've got my own opinion, but Steve's audit
> > > > > > userspace is not my project to manage and I think we've established
> > > > > > over the years that Steve and I have very different views on what
> > > > > > constitutes good design.
> > > > >
> > > > > And guessing what might be in buffers of different sizes is good
> > design?
> > > > > The FEATURE_BITMAP was introduced to get rid of this ambiguity.
> > > >
> > > > There is just soo much to unpack in your comment Steve, but let me
> > > > keep it short ...
> > > >
> > > > - This is an enterprise distro problem, not an upstream problem.  The
> > > > problems you are talking about are not a problem for upstream.
> > >
> > > You may look at it that way. I do not. Audit -userspace is also an
> > upstream
> > > for a lot of distros and I need to make this painless for them. So,
> > while you
> > > may think of this being a backport problem for Red Hat to solve, I think
> > of
> > > this as a generic problem that I'd like to solve for Debian, Suse,
> > Ubuntu,
> > > Arch, Gentoo, anyone using audit. We both are upstream.
> >
> > I intentionally said "enterprise Linux distributions", I never singled
> > out RH/IBM.  Contrary to what RH/IBM marketing may have me believe, I
> > don't consider RHEL to be the only "enterprise Linux distribution" :)
> >
> > Beyond that, while I haven't looked at all of the distros you list
> > above, I know a few of them typically only backport fixes, not new
> > features.  Further, as I mentioned previously in this thread, there is
> > a way to backport this feature in a safe manner without using the
> > feature bits.  Eeeeeven further, if there wasn't a way to backport
> > this feature safely (and let me stress agai that you can backport this
> > safely), I would still consider that to be a distro problem and not an
> > upstream kernel problem.  The upstream kernel is not responsible for
> > enabling or supporting arbitrary combinations of patches.
> >
> > --
> > paul moore
> > www.paul-moore.com
> >
> > --
> > Linux-audit mailing list
> > Linux-audit@redhat.com
> > https://www.redhat.com/mailman/listinfo/linux-audit
> >
> >
> Hi Steve, Paul,
>
> I'm replying with the Gmail UI since I don't have my Mutt setup handy, so
> apologies for any formatting which doesn't align with the mailing list best
>  practices!
>
> First off, my apologies for being late to the thread, and for submitting
> code
> to the kernel and user space which aren't playing nicely with each other.
>
> It sounds like there's a decision to be made around whether or not to use
> the bitmap feature flags which I probably am probably not in a position to
> help decide. However, I'm more than happy to fix my userspace PR so
> that it does not rely on the feature flag space using the approach Paul
> outlined, in spite of the drawbacks, if that ends up being the decision.
>
> Steve, I understand your preference to rely on the feature bitmap since it
> is a more reliable way to determine the availability of a feature than
> key size, but if you're open to Paul's recommendations in spite of the
> drawbacks, I'll make the changes to my patch as soon as I can to unblock
> your work.
>
> Separately, since there is tension between these two approaches
> (structure size and bitmap), I wonder if Paul/Steve you would be open
> to a third way.

Max, Steve: have you looked at my reply in this thread from 2020-12-03 18:10?

There are two solutions in there that should work without relying on the
unreliable test for structure size that work without changing the
currently commited kernel code.  Or have I missed something?

> For example, I can imagine adding additional bitmap
> spaces (FEATURE_BITMAP_2, FEATURE_BITMAP_3, etc.).
> Alternately, I can imagine each feature being assigned a unique u64
> ID, and user space programs querying the kernel to see whether a
> a particular feature is enabled.
>
> I'm not familiar enough with the kernel to be able to judge how sound
> either idea is (or if these have been considered and rejected in the past)
> but if you all think a third way is viable, I'd be happy to start a separate
> mailing thread to try to thread the competing requirements of the kernel
> and userspace, and contribute code if we can find a solution.
>
> Max

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635