On 7/9/20 9:07 AM, Andy Lutomirski wrote:
On Thu, Jul 9, 2020 at 8:56 AM Dave Hansen dave.hansen@intel.com wrote:
On 7/9/20 8:44 AM, Andersen, John wrote:
Bits which are allowed to be pinned default to WP for CR0 and SMEP, SMAP, and UMIP for CR4.
I think it also makes sense to have FSGSBASE in this set.
I know it hasn't been tested, but I think we should do the legwork to test it. If not in this set, can we agree that it's a logical next step?
I have no objection to pinning FSGSBASE, but is there a clear description of the threat model that this whole series is meant to address? The idea is to provide a degree of protection against an attacker who is able to convince a guest kernel to write something inappropriate to CR4, right? How realistic is this?
If a quick search can find this:
https://googleprojectzero.blogspot.com/2017/05/exploiting-linux-kernel-via-p...
I'd pretty confident that the guys doing actual bad things have it in their toolbox too.