Re: MLS dominance check behavior on el7

[Ted Toth <txtoth@gmail.com>]

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On Wed, Sep 12, 2018 at 9:36 AM Dominick Grift <dac.override@gmail.com>
wrote:

> On Wed, Sep 12, 2018 at 09:57:20AM -0400, Stephen Smalley wrote:
> > On 09/12/2018 09:26 AM, Ted Toth wrote:
> > >
> > >
> > > On Wed, Sep 12, 2018 at 8:04 AM Stephen Smalley <sds@tycho.nsa.gov
> > > <mailto:sds@tycho.nsa.gov>> wrote:
> > >
> > >     On 09/11/2018 04:59 PM, Ted Toth wrote:
> > >      > That's awesome and now it's got me thinking about other
> > >      > classes/permissions that we could implement. Can cil macros can
> be
> > >      > referenced in .te/.if files?
> > >
> > >     Not sure I understand your question.  You can't directly embed cil
> > >     statements in .te/.if files.  However, if you define a
> class/permission
> > >     in a .cil module, you can certainly specify a require on it and
> use it
> > >     from a conventional .te/.if module, ala:
> > >     $ cat > usemcstrans.te <<EOF
> > >     policy_module(usemcstrans, 1.0)
> > >
> > >     require {
> > >              class mcstrans { color_use };
> > >              attribute domain;
> > >     }
> > >
> > >     allow domain self:mcstrans color_use;
> > >     EOF
> > >
> > >     $ make -f /usr/share/selinux/devel/Makefile usemcstrans.pp
> > >     $ sudo semodule -i usemcstrans.pp
> > >
> > >
> > > If the cil contained:
> > >
> > > (macro use_color (type caller) (allow caller self mcstrans
> (color_use)))
> > >
> > > then in x.te can I use the macro:
> > >
> > > type x_t;
> > > use_color(x_t)
> >
> > Sorry, no.  The macros used in .te/.if files are just m4 definitions
> handled
> > at the preprocessing stage, not a feature of the module language.  The
> CIL
> > macros are directly supported by the CIL compiler, but they won't be
> visible
> > to the module compiler.  Also, you are missing several parentheses above
> > (I'm not fond of the lisp-like syntax myself).  In a CIL module, I think
> the
> > correct syntax would be:
> >
> > (macro use_color ((type caller)) (allow caller self (mcstrans
> (color_use))))
> >
> > (call use_color(x_t))
> >
> > Or you could define a m4 macro in an .if file and use that in a .te file.
> > Or both.
> >
>
> Ideally you would have all of your policy written in CIL or in a
> high-level language that was designed to leverage CIL.
>

Unfortunately I/we don't live in an ideal world :( but thanks for the
pointers.


>
> My DSSP2 policy is a CIL-only policy. In there I also leverage unordered
> classes, Meaning that for example if you remove or disable the mcstrans
> module then you automatically also remove or disable  the access vectors
> that mcstrans manages.
>
> minimal:
>
> https://github.com/DefenSec/dssp2-minimal
>
> standard (my personal policy based on top of minimal):
>
> https://github.com/DefenSec/dssp2-standard/commits/master
>
> DSSP2 does not support enforcement of confidentiality though
>
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> Dominick Grift
>

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