linux-kernel - Re: [PATCH 1/3] userfaultfd/sysctl: introduce unprivileged

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190312135316.GA22990@rapoport-lnx>
Date:   Tue, 12 Mar 2019 15:53:17 +0200
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Maxime Coquelin <maxime.coquelin@...hat.com>,
        kvm@...r.kernel.org, Jerome Glisse <jglisse@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Martin Cracauer <cracauer@...s.org>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>, linux-mm@...ck.org,
        Marty McFadden <mcfadden8@...l.gov>,
        Maya Gokhale <gokhale2@...l.gov>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        linux-fsdevel@...r.kernel.org,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/3] userfaultfd/sysctl: introduce
 unprivileged_userfaultfd

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.