Re: [PATCH, RFC 45/62] mm: Add the encrypt_mprotect() system call for MKTME

From: Kai Huang
Date: Mon Jun 17 2019 - 20:53:56 EST

> > And another silly argument: if we had /dev/mktme, then we could
> > possibly get away with avoiding all the keyring stuff entirely.
> > Instead, you open /dev/mktme and you get your own key under the hook.
> > If you want two keys, you open /dev/mktme twice. If you want some
> > other program to be able to see your memory, you pass it the fd.
> We still like the keyring because it's one-stop-shopping as the place
> that *owns* the hardware KeyID slots. Those are global resources and
> scream for a single global place to allocate and manage them. The
> hardware slots also need to be shared between any anonymous and
> file-based users, no matter what the APIs for the anonymous side.

MKTME driver (who creates /dev/mktme) can also be the one-stop-shopping. I think whether to choose
keyring to manage MKTME key should be based on whether we need/should take advantage of existing key
retention service functionalities. For example, with key retention service we can
revoke/invalidate/set expiry for a key (not sure whether MKTME needs those although), and we have
several keyrings -- thread specific keyring, process specific keyring, user specific keyring, etc,
thus we can control who can/cannot find the key, etc. I think managing MKTME key in MKTME driver
doesn't have those advantages.