[PATCH 0/7] Kernel Userspace Protection for radix

[Russell Currey]

On Thu, 2019-02-21 at 08:07 -0800, Kees Cook wrote:
> On Thu, Feb 21, 2019 at 1:36 AM Russell Currey <ruscur at russell.cc>
> wrote:
> > The first three patches of these series are from Christophe's work
> > and are
> > the bare minimum framework needed to implement the support for
> > radix.
> > 
> > In patch 3, I have removed from Christophe's patch my
> > implementation of
> > the 64-bit exception handling code, since we don't have an answer
> > for
> > making nested exceptions work yet.  This is mentioned in the final
> > KUAP
> > patch.  Regardless, this is still a significant security
> > improvement
> > and greatly narrows the attack surface.
> 
> Nice! Am I understanding correctly that with this series powerpc9 and
> later, using radix, will pass the lkdtm tests for KUAP and KUEP (i.e.
> EXEC_USERSPACE and ACCESS_USERSPACE)?

Yes!  We've had execution prevention for a while on radix (which is
default on POWER9) since 3b10d0095a1e, the only functional thing this
series does is allow disabling it with nosmep.  This series adds access
prevention.