On 7/9/20 9:07 AM, Andy Lutomirski wrote: > On Thu, Jul 9, 2020 at 8:56 AM Dave Hansen <dave.hansen@xxxxxxxxx> 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-packet.html I'd pretty confident that the guys doing actual bad things have it in their toolbox too.
