Re: [Xen-devel] [PATCH v7 10/10] xen/common: do not implicitly permit access to mapped I/O memory

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Jan,

On 06/05/14 10:06, Jan Beulich wrote:
> > @@ -838,7 +842,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> > u_domctl)
> >               break;
> >
> >           ret = -EPERM;
> > -        if ( !iomem_access_permitted(current->domain, mfn, mfn_end) )
> > +        if ( !iomem_access_permitted(d, mfn, mfn_end) )
> I'm not sure if we shouldn't rather be conservative here and check
> both domains' permissions.
I think we only need to check the permission of the current domain. 
Checking the permission of the guest is not necessary here. Hence, the 
code to map a region will be more difficult. We will have first call 
iomem_permission then call memory_mapping.
I would prefer to keep the current permission check ie:

if ( !iomem_access_permitted(current->domain, ...) )

Regards,

--
Julien Grall

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