On Wed, 2024-02-14 at 19:32 +0100, Petr Tesařík wrote:

quoted

What use case needs to have the sandbox both protected from the
kernel
(trusted operations) and non-privileged (the kernel protected from
it
via CPL3)? It seems like opposite things.

I think I have mentioned one: parsing keys for the trusted keyring.
The
parser is complex enough to be potentially buggy, but the security
folks have already dismissed the idea to run it as a user mode
helper.

Ah, I didn't realize the kernel needed to be protected from the key
parsing part because you called it out as a trusted operation. So on
the protect-the-kernel-side it's similar to the microkernel security
reasoning.

Did I get the other part wrong - that you want to protect the sandbox
from the rest of kernel as well?