From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2FFCC43381 for ; Tue, 12 Mar 2019 12:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C59120883 for ; Tue, 12 Mar 2019 12:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726661AbfCLM0s (ORCPT ); Tue, 12 Mar 2019 08:26:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33214 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726304AbfCLM0r (ORCPT ); Tue, 12 Mar 2019 08:26:47 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6628759445; Tue, 12 Mar 2019 12:26:46 +0000 (UTC) Received: from xz-x1 (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 10A3A6684E; Tue, 12 Mar 2019 12:26:35 +0000 (UTC) Date: Tue, 12 Mar 2019 20:26:33 +0800 From: Peter Xu To: Mike Rapoport Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , kvm@vger.kernel.org, Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , linux-mm@kvack.org, Marty McFadden , Maya Gokhale , Mike Kravetz , Andrea Arcangeli , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , linux-fsdevel@vger.kernel.org, "Dr . David Alan Gilbert" , Andrew Morton Subject: Re: [PATCH 1/3] userfaultfd/sysctl: introduce unprivileged_userfaultfd Message-ID: <20190312122633.GE14108@xz-x1> References: <20190311093701.15734-1-peterx@redhat.com> <20190311093701.15734-2-peterx@redhat.com> <20190312065830.GB9497@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190312065830.GB9497@rapoport-lnx> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 12 Mar 2019 12:26:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. :) Thanks! -- Peter Xu