Fedora buildsys and SELinux

[Stephen Smalley]

On Tue, 2008-04-22 at 11:55 -0400, Stephen Smalley wrote:
> On Thu, 2008-04-17 at 09:12 -0400, Stephen Smalley wrote:
> > On Wed, 2008-04-16 at 23:23 -0400, Bill Nottingham wrote:
> > > James Morris (jmorris at namei.org) said: 
> > > > > You cannot create files in a chroot of a context not known by the
> > > > > host policy. This means that if your host is running RHEL 5, you are
> > > > > unable to compose any trees/images/livecds with SELinux enabled for
> > > > > later releases.
> > > > 
> > > > Ok, that's what I suspected.
> > > > 
> > > > One of the possible plans for this is to allow a process to run in a 
> > > > separate policy namespace, and probably also utilize namespace support in 
> > > > general.
> > > > 
> > > > This is non-trivial and needs more analysis.
> > > 
> > > Incidentally, this is also one of the blockers for policy-in-packages,
> > > rather than a monolithic one.
> > 
> > I assume you mean setting down unknown file labels rather than
> > per-namespace or per-chroot policy support.  I think they are related
> > but different.  The former is required if you always plan to install the
> > files _before_ loading the policy.  The latter is required primarily for
> > getting any scriptlets to run in the right security contexts so that any
> > files they create are labeled appropriately within the chroot.
> 
> BTW, for reference, a patch to support setting down unknown file labels
> was posted here a couple of years ago:
> http://marc.info/?l=selinux&m=114771094617968&w=2

And the last version of that patch was:
http://marc.info/?l=selinux&m=114840466518263&w=2
Not that it applies cleanly anymore, of course.

> But unfortunately we weren't able to sort the remaining issues discussed
> in that thread.
> 
> > Also, I wanted to emphasize that chroot is different than unsharing the
> > filesystem namespace, and per-chroot policy is not the same thing as
> > per-namespace policy.  I'd expect though that it would actually be a
> > per-process policy mechanism, with most processes sharing the same
> > policy but programs like rpm being able to unshare policy from their
> > parent and then load a private policy to be applied only to their
> > descendants.
> >   
-- 
Stephen Smalley
National Security Agency