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From:   Paul Moore <paul@paul-moore.com>
Date:   Wed, 18 Oct 2023 21:39:10 -0400
Message-ID: <CAHC9VhSx0UiHyQYR-=va4X0r3XpEFz9n9f96DkQ9bhbB97RnnQ@mail.gmail.com>
Subject: Re: [PATCH][RFC] selinuxfs: saner handling of policy reloads
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     selinux@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Christian Brauner <brauner@kernel.org>,
        selinux-refpolicy@vger.kernel.org
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On Wed, Oct 18, 2023 at 12:35=E2=80=AFAM Al Viro <viro@zeniv.linux.org.uk> =
wrote:
> On Tue, Oct 17, 2023 at 04:28:53PM -0400, Paul Moore wrote:
> > Thanks Al.
> >
> > Giving this a very quick look, I like the code simplifications that
> > come out of this change and I'll trust you on the idea that this
> > approach is better from a VFS perspective.
> >
> > While the reject_all() permission hammer is good, I do want to make
> > sure we are covered from a file labeling perspective; even though the
> > DAC/reject_all() check hits first and avoids the LSM inode permission
> > hook, we still want to make sure the files are labeled properly.  It
> > looks like given the current SELinux Reference Policy this shouldn't
> > be a problem, it will be labeled like most everything else in
> > selinuxfs via genfscon (SELinux policy construct).  I expect those
> > with custom SELinux policies will have something similar in place with
> > a sane default that would cover the /sys/fs/selinux/.swapover
> > directory but I did add the selinux-refpol list to the CC line just in
> > case I'm being dumb and forgetting something important with respect to
> > policy.
> >
> > The next step is to actually boot up a kernel with this patch and make
> > sure it doesn't break anything.  Simply booting up a SELinux system
> > and running 'load_policy' a handful of times should exercise the
> > policy (re)load path, and if you want a (relatively) simple SELinux
> > test suite you can find one here:
> >
> > * https://github.com/SELinuxProject/selinux-testsuite
> >
> > The README.md should have the instructions necessary to get it
> > running.  If you can't do that, and no one else on the mailing list is
> > able to test this out, I'll give it a go but expect it to take a while
> > as I'm currently swamped with reviews and other stuff.
>
> It does survive repeated load_policy (as well as semodule -d/semodule -e,
> with expected effect on /booleans, AFAICS).  As for the testsuite...
> No regressions compared to clean -rc5, but then there are (identical)
> failures on both - "Failed 8/76 test programs. 88/1046 subtests failed."
> Incomplete defconfig, at a guess...

Thanks for the smoke testing, the tests should run clean, but if you
didn't adjust the Kconfig you're likely correct that it is the source
of the failures.  I'll build a kernel with the patch and give it a
test.

From what I can see, it doesn't look like this is a candidate for
stable, correct?

--=20
paul-moore.com