Re: [RFC PATCH 00/11] Kernel FineIBT Support

Joao Moreira
2022-04-20T22:50:24Z

> I think it'd be good to get kCFI landed in Clang first (since it is
> effectively architecture agnostic), and then get FineIBT landed. But
> that doesn't mean we can't be working on the kernel side of things at
> the same time.

FWIIW, I'm effectively taking some time away from work for the next 3
months. I'll be around to answer this and that, help reviewing KCFI and
maybe send small fixes around, but I'm not planning to land FineIBT in
clang anytime before that (specially now that I have a direction to look
into the linker approach as per the other thread e-mails). This should
give KCFI the time it needs to squeeze in.

>
> And just thinking generally, for other architecture-specific stuff,
> I do wonder what an arm64 PAC-based CFI might look like. I prefer
> things
> be hard-coded as kCFI is doing, but it'd be nice to be able to directly
> measure performance and size overheads comparing the various methods.

There are other important bullets to this list, I think, like power
consumption, robustness and collateral gains (like IBT's side-channel
hardening). But yeah, this is probably a good list to keep in mind for
us to discuss during plumbers :)