WARNING in apparmor_secid_to_secctx

On 09/04/2018 11:38 AM, Dmitry Vyukov wrote:

On Tue, Sep 4, 2018 at 5:28 PM, Stephen Smalley [off-list ref] wrote:

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So why not ask for help from the SELinux community? I've cc'd the selinux
list and a couple of folks involved in Debian selinux.  I see a couple of
options but I don't know your constraints for syzbot:

1) Run an instance of syzbot on a distro that supports SELinux enabled
out
of the box like Fedora. Then you don't have to fight with SELinux and can
just focus on syzbot, while still testing SELinux enabled and enforcing.

2) Report the problems you are having with enabling SELinux on newer
Debian
to the selinux list and/or the Debian selinux package maintainers so that
someone can help you resolve them.

3) Back-port the cgroup2 policy definitions to your wheezy policy,
rebuild
it, and install that.  We could help provide guidance on that. I think
you'll need to rebuild the base policy on wheezy; in distributions with
modern SELinux userspace, one could do it just by adding a CIL module
locally.

Thanks, Stephen!

I would like to understand first if failing mount(2) for unknown fs is
selinux bug or not. Because if it is and it is fixed, then it would
resolve the problem without actually doing anything (well, at least on
our side :)).

Yes, I think that's a selinux kernel regression, previously reported here:
https://lkml.org/lkml/2017/10/6/658

Unfortunately I don't think it has been fixed upstream.  Generally people
using SELinux with a newer kernel are also using a newer policy. That said,
I agree it is a regression and ought to be fixed.

How hard is it to fix it? We are on upstream head, so once it's in we
are ready to go.
Using multiple images is somewhat problematic (besides the fact that I
don't know how to build a fedora image) because syzbot does not
capture what image was used, and in the docs we just provide the
single image, so people will start complaining that bugs don't
reproduce but they are just using a wrong image.

I'll take a look and see if I can provide a trivial fix.