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Re: Fedora buildsys and SELinux



On Tue, 2008-04-22 at 12:38 -0400, Stephen Smalley wrote:
> 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 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.

Note for anyone trying to revive that patch:  please be sure to
introduce a new security class for that permission instead of adding it
to the security class as I did in that patch, so that we can be certain
that this new ability won't be allowed to unconfined domains by default.
We do not want unconfined_t user shells to be able to set arbitrary
label values w/o no warning that it wasn't valid; we want to limit this
to specific programs like rpm that will be aware of the implications and
(hopefully) do some validity checking of their own afterward.

-- 
Stephen Smalley
National Security Agency


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