Re: [PATCH 1/3] userfaultfd/sysctl: introduce unprivileged_userfaultfd

Mike Rapoport
2019-03-12T13:53:17Z

On Tue, Mar 12, 2019 at 08:26:33PM +0800, Peter Xu wrote:
> On Tue, Mar 12, 2019 at 08:58:30AM +0200, Mike Rapoport wrote:
>
> [...]
>
> > > +config USERFAULTFD_UNPRIVILEGED_DEFAULT
> > > + string "Default behavior for unprivileged userfault syscalls"
> > > + depends on USERFAULTFD
> > > + default "disabled"
> > > + help
> > > + Set this to "enabled" to allow userfaultfd syscalls from
> > > + unprivileged users. Set this to "disabled" to forbid
> > > + userfaultfd syscalls from unprivileged users. Set this to
> > > + "kvm" to forbid unpriviledged users but still allow users
> > > + who had enough permission to open /dev/kvm.
> >
> > I'd phrase it a bit differently:
> >
> > This option controls privilege level required to execute userfaultfd
> ^
> +---- add " the default"?
>
> > system call.
> >
> > Set this to "enabled" to allow userfaultfd system call from unprivileged
> > users.
> > Set this to "disabled" to allow userfaultfd system call only for users who
> > have ptrace capability.
> > Set this to "kvm" to restrict userfaultfd system call usage to users with
> ^
> add " who have ptrace capability, or" -------+
>
> > permissions to open "/dev/kvm".
>
> I think your version is better than mine, but I'd like to confirm
> about above two extra changes before I squash them into the patch. :)

I like your changes.

> Thanks!
>
> --
> Peter Xu
>

--
Sincerely yours,
Mike.