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Re: I am concerned about putting genhomedircon changes in libsemanage into Fedora 8.

From: Stephen Smalley <sds_at_tycho.nsa.gov>
Date: Wed, 26 Sep 2007 10:52:31 -0400


On Wed, 2007-09-26 at 10:47 -0400, Joshua Brindle wrote:
> Daniel J Walsh wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Daniel J Walsh wrote:
> >
> >> I may hold off on this so we can get a full Rawhide cycle on it.
> >> genhomedircon has many corner cases and do not want to risk blowing F-8
> >> now that we are at Feature Freeze.
> >> All the rest of the patches have been integrated.
> >
> >
> >
> > The genhomedircon replacement is broken in libsemanage. It is
> > generating invalid file context. The python version verified the
> > file context it was creating were valid before assiging them. This is
> > resulting in Fedora Core 8 not being able to autorelabel
> >
> >
>
> The python version did the wrong thing entirely. It validated the
> contexts against the running policy in the kernel, which breaks when you
> try to do an operation on another store. Also since we moved
> genhomedircon inside of libsemanage the new policy isn't even loaded yet
> so we can't validate against the kernel (or the new types added by the
> module being added would be 'invalid'). The only real way to validate
> the contexts now would be to load the newly generated policy into the
> libsepol security server and to the context validations on it.

i.e. sepol_set_policydb_from_file() on the policy, and then sepol_check_context() on the contexts, as is done by setfiles -c.

> This would work, it would just take extra time at module load time. It
> seems like the real problem is that the invalid contexts are being
> generated in the first place, relying on genhomedircon to sanity check
> your file contexts seems like you are punting the problem.

I think the problem is that the templating mechanism isn't sufficiently flexible; the per-role contexts aren't necessarily valid for all cases.

In any event, this is a regression between the old genhomedircon and the libsemanage reimplementation and should have been called out as a change in behavior in the patch set, even if the old behavior was flawed.

So I guess Dan needs to stay with the old genhomedircon and libsemanage for Fedora 8.

-- 
Stephen Smalley
National Security Agency


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Received on Wed 26 Sep 2007 - 11:01:10 EDT
 

Date Posted: Jan 15, 2009 | Last Modified: Jan 15, 2009 | Last Reviewed: Jan 15, 2009

 
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