Messages in this thread | | | Date | Thu, 7 May 2020 13:15:03 -0600 | From | Jonathan Corbet <> | Subject | Re: [PATCH 2/2] Add a new sysctl knob: unprivileged_userfaultfd_user_mode_only |
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On Wed, 6 May 2020 15:38:16 -0400 Peter Xu <peterx@redhat.com> wrote:
> If this is going to be added... I am thinking whether it should be easier to > add another value for unprivileged_userfaultfd, rather than a new sysctl. E.g.: > > "0": unprivileged userfaultfd forbidden > "1": unprivileged userfaultfd allowed (both user/kernel faults) > "2": unprivileged userfaultfd allowed (only user faults) > > Because after all unprivileged_userfaultfd_user_mode_only will be meaningless > (iiuc) if unprivileged_userfaultfd=0. The default value will also be the same > as before ("1") then.
It occurs to me to wonder whether this interface should also let an admin block *privileged* user from handling kernel-space faults? In a secure-boot/lockdown setting, this could be a hardening measure that keeps a (somewhat) restricted root user from expanding their privilege...?
jon
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