Re: [RFC v2 00/27] Kernel Address Space Isolation

[Peter Zijlstra]

On Fri, Jul 12, 2019 at 06:37:47PM +0200, Alexandre Chartre wrote:
> On 7/12/19 5:16 PM, Thomas Gleixner wrote:

> > Right. If we decide to expose more parts of the kernel mappings then that's
> > just adding more stuff to the existing user (PTI) map mechanics.
> 
> If we expose more parts of the kernel mapping by adding them to the existing
> user (PTI) map, then we only control the mapping of kernel sensitive data but
> we don't control user mapping (with ASI, we exclude all user mappings).
> 
> How would you control the mapping of userland sensitive data and exclude them
> from the user map? Would you have the application explicitly identify sensitive
> data (like Andy suggested with a /dev/xpfo device)?

To what purpose do you want to exclude userspace from the kernel
mapping; that is, what are you mitigating against with that?