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

[Mike Rapoport <rppt@linux.ibm.com>]

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.