Re: [Xen-devel] [PATCH] xsm/flask: Handle policy load failures properly

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 24/02/2015 09:39, Ian Campbell wrote:
> On Tue, 2015-02-24 at 09:31 +0000, Julien Grall wrote:
> > On 24/02/2015 08:47, Ian Campbell wrote:
> > > On Mon, 2015-02-23 at 12:53 -0500, Daniel De Graaf wrote:
> > > > When no policy is loaded, the FLASK policy is equivalent to an allow-all
> > > > policy; see xen/xsm/flask/ss/services.c:security_compute_av where it
> > > > bails out if !ss_initialized.  It could be considered as either enforcing
> > > > or being permissive with an allow-all policy, but the actual access is
> > > > the same.
> > > Do you think anyone would want an option to be provided which causes Xen
> > > to fail to boot if a proper policy isn't provided (and loaded)? Similar
> > > to how iommu=force works.
> > >
> > > I can see how osstest testcases for xsm might want this to avoid
> > > accidentally testing with no policy, but not sure if it would be
> > > considered generally useful enough to be added.
> > I think it would make sense to panic when flask_enforcing is enabled and
> > the policy is not loaded or valid.
> That would stop you running in enforcing mode with a late loaded policy.
> A separate flag to enforce boot time loading was what I was thinking of.
You can enforce the policy later via xl setenforce.

So if someone wants to load a policy later and enforced it, he would 
have to call :
        - xl loadpolicy
        - xl setenforce

IHMO, when you set flask_enforcing on the command line, you expect to 
pass a policy via the bootloader.
Regards,

--
Julien Grall

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