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=unavailable 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 EBBE5C43381 for ; Wed, 13 Mar 2019 23:55:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1FA721019 for ; Wed, 13 Mar 2019 23:55:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727242AbfCMXzk (ORCPT ); Wed, 13 Mar 2019 19:55:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46442 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726784AbfCMXzk (ORCPT ); Wed, 13 Mar 2019 19:55:40 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 49E6730018EB; Wed, 13 Mar 2019 23:55:40 +0000 (UTC) Received: from sky.random (ovpn-121-1.rdu2.redhat.com [10.10.121.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8461F60F94; Wed, 13 Mar 2019 23:55:35 +0000 (UTC) Date: Wed, 13 Mar 2019 19:55:34 -0400 From: Andrea Arcangeli To: Mike Kravetz Cc: Paolo Bonzini , Peter Xu , linux-kernel@vger.kernel.org, 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 Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , linux-fsdevel@vger.kernel.org, "Dr . David Alan Gilbert" , Andrew Morton Subject: Re: [PATCH 0/3] userfaultfd: allow to forbid unprivileged users Message-ID: <20190313235534.GK25147@redhat.com> References: <20190311093701.15734-1-peterx@redhat.com> <58e63635-fc1b-cb53-a4d1-237e6b8b7236@oracle.com> <20190313060023.GD2433@xz-x1> <3714d120-64e3-702e-6eef-4ef253bdb66d@redhat.com> <20190313185230.GH25147@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 13 Mar 2019 23:55:40 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 13, 2019 at 01:01:40PM -0700, Mike Kravetz wrote: > On 3/13/19 11:52 AM, Andrea Arcangeli wrote: > > > > hugetlbfs is more complicated to detect, because even if you inherit > > it from fork(), the services that mounts the fs may be in a different > > container than the one that Oracle that uses userfaultfd later on down > > the road from a different context. And I don't think it would be ok to > > allow running userfaultfd just because you can open a file in an > > hugetlbfs file system. With /dev/kvm it's a bit different, that's > > chmod o-r by default.. no luser should be able to open it. > > > > Unless somebody suggests a consistent way to make hugetlbfs "just > > work" (like we could achieve clean with CRIU and KVM), I think Oracle > > will need a one liner change in the Oracle setup to echo into that > > file in addition of running the hugetlbfs mount. > > I think you are suggesting the DB setup process enable uffd for all users. > Correct? Yes. In addition of the hugetlbfs setup, various apps requires to also increase fs.inotify.max_user_watches or file-max and other tweaks, this would be one of those tweaks. > This may be too simple, and I don't really like group access, but how about > just defining a uffd group? If you are in the group you can make uffd > system calls. Everything is possible, I'm just afraid it gets too complex. So you suggest to echo a gid into the file?