Re: [PATCH v3 2/6] userfaultfd: add /dev/userfaultfd for fine grained access control

[Andrew Morton]

On Wed,  1 Jun 2022 14:09:47 -0700 Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote:

> To achieve this, add a /dev/userfaultfd misc device. This device
> provides an alternative to the userfaultfd(2) syscall for the creation
> of new userfaultfds. The idea is, any userfaultfds created this way will
> be able to handle kernel faults, without the caller having any special
> capabilities. Access to this mechanism is instead restricted using e.g.
> standard filesystem permissions.

The use of a /dev node isn't pretty.  Why can't this be done by
tweaking sys_userfaultfd() or by adding a sys_userfaultfd2()?

Peter, will you be completing review of this patchset?