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=-2.2 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 66D03C3A5A2 for ; Fri, 23 Aug 2019 14:24:59 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3BD282173E for ; Fri, 23 Aug 2019 14:24:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3BD282173E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56688 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1AUs-0000hH-6R for qemu-devel@archiver.kernel.org; Fri, 23 Aug 2019 10:24:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48173) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1AR7-0005H4-NS for qemu-devel@nongnu.org; Fri, 23 Aug 2019 10:21:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i1AR4-0000Wq-WD for qemu-devel@nongnu.org; Fri, 23 Aug 2019 10:21:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35140) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i1AR4-0000WP-O6 for qemu-devel@nongnu.org; Fri, 23 Aug 2019 10:21:02 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D79F37EB88; Fri, 23 Aug 2019 14:21:01 +0000 (UTC) Received: from redhat.com (ovpn-112-60.ams2.redhat.com [10.36.112.60]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 39D161001B12; Fri, 23 Aug 2019 14:20:57 +0000 (UTC) Date: Fri, 23 Aug 2019 15:20:54 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Message-ID: <20190823142054.GK9654@redhat.com> References: <20190808150325.21939-1-marcandre.lureau@redhat.com> <20190823112053.GE9654@redhat.com> <20190823114157.GG9654@redhat.com> <20190823130014.GG2784@work-vm> <20190823140948.GI2784@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190823140948.GI2784@work-vm> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.71]); Fri, 23 Aug 2019 14:21:01 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Laurent Vivier , Thomas Huth , Juan Quintela , qemu-devel , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Aug 23, 2019 at 03:09:48PM +0100, Dr. David Alan Gilbert wrote: > * Marc-Andr=C3=A9 Lureau (marcandre.lureau@gmail.com) wrote: > > Hi > >=20 > > On Fri, Aug 23, 2019 at 5:00 PM Dr. David Alan Gilbert > > wrote: > > > > > > * Daniel P. Berrang=C3=A9 (berrange@redhat.com) wrote: > > > > > > > > > > > > > This means QEMU still has to iterate over every single client > > > > on the bus to identify them. If you're doing that, there's > > > > no point in owning a well known service at all. Just iterate > > > > over the unique bus names and look for the exported object > > > > path /org/qemu/VMState > > > > > > > > > > Not knowing anything about DBus security, I want to ask how do > > > we handle security here? > >=20 > > First of all, we are talking about cooperative processes, and having = a > > specific bus for each qemu instance. So some amount of security/trust > > is already assumed. >=20 > Some but we need to keep it as limited as possible; for example two > reasons for having separate processes both come down to security: >=20 > a) vtpm - however screwy the qemu is, you can never get to the keys i= n > the vtpm Processes connected to dbus can only call the DBus APIs that vtpm actually exports. The vtpm should simply *not* export a DBus API that allows anything to fetch the keys. If it did want to export APIs for fetching keys, then we would have to ensure suitable dbus /selinux policy was created to prevent unwarranted access. > b) virtio-gpu, loads of complex GPU code that can't break the main > qemu process. That's no problem - virtio-gpu crashes, it disappears from the dbus bus, but everything else keeps running. > > But if necessary, dbus can enforce policies on who is allowed to own = a > > name, or to send/receive message from. As far as I know, this is > > mostly user/group policies. > >=20 > > But there is also SELinux checks to send_msg and acquire_svc (see > > dbus-daemon(1)) >=20 > But how does something like SELinux interact with a private dbus=20 > rather than the system dbus? There's already two dbus-daemon's on each host - the system one and the session one, and they get different selinux contexts, system_dbus_t and unconfined_dbus_t. Since libvirt would be responsible for launching these private dbus daemons it would be easy to make it run svirt_dbus_t for example. Actually it would be svirt_dbus_t:s0:cNNN,cMMM to get uniqueness per VM. Will of course require us to talk to the SELinux maintainers to get some sensible policy rules created. > > > I want to know that the external device that's giving me migration = data > > > is the device I think I'm speaking to, not one of the other devices= ; > >=20 > > DBus is not the problem nor the solution here. >=20 > Well, if the migration data was squirting down the existing vhost-user > channel then there would be no risk here; so the use of dbus is creatin= g > the problem. >=20 > > But what defines that device-service strong relationship? Can you > > generalize it? I don't think so. > >=20 > > What DBus can guarantee is that the unique-id you are talking to is > > always the same connection (thus the same process). > >=20 > > > I also dont want different devices chatting to each other over dbus > > > unless we're very careful. > >=20 > > That's a bus policy job. >=20 > OK, as long as you somehow set it up. >=20 > Dave >=20 > > > > > > Dave > > > > > > > Regards, > > > > Daniel > > > > -- > > > > |: https://berrange.com -o- https://www.flickr.com/photos= /dberrange :| > > > > |: https://libvirt.org -o- https://fstop138.be= rrange.com :| > > > > |: https://entangle-photo.org -o- https://www.instagram.com= /dberrange :| > > > -- > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > >=20 > >=20 > > --=20 > > Marc-Andr=C3=A9 Lureau > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|