From xen-devel-bounces@lists.xen.org Tue Sep 17 10:30:04 2013 Received: (at maildrop) by bugs.xenproject.org; 17 Sep 2013 09:30:04 +0000 Received: from lists.xen.org ([50.57.142.19]) by bugs.xenproject.org with esmtp (Exim 4.80) (envelope-from ) id 1VLrbg-00086I-T7 for xen-devel-maildrop-Eithu9ie@bugs.xenproject.org; Tue, 17 Sep 2013 10:30:04 +0100 Received: from localhost ([127.0.0.1] helo=lists.xen.org) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VLrYv-0002cu-2z; Tue, 17 Sep 2013 09:27:13 +0000 Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VLrYt-0002cp-SQ for xen-devel@lists.xen.org; Tue, 17 Sep 2013 09:27:12 +0000 Received: from [85.158.139.211:18353] by server-14.bemta-5.messagelabs.com id C2/39-12040-F6028325; Tue, 17 Sep 2013 09:27:11 +0000 X-Env-Sender: Ian.Jackson@eu.citrix.com X-Msg-Ref: server-9.tower-206.messagelabs.com!1379410028!2864101!1 X-Originating-IP: [66.165.176.89] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogNjYuMTY1LjE3Ni44OSA9PiAyMDMwMDc=\n X-StarScan-Received: X-StarScan-Version: 6.9.12; banners=-,-,- X-VirusChecked: Checked Received: (qmail 24778 invoked from network); 17 Sep 2013 09:27:10 -0000 Received: from smtp.citrix.com (HELO SMTP.CITRIX.COM) (66.165.176.89) by server-9.tower-206.messagelabs.com with RC4-SHA encrypted SMTP; 17 Sep 2013 09:27:10 -0000 X-IronPort-AV: E=Sophos;i="4.90,922,1371081600"; d="scan'208";a="54587190" Received: from accessns.citrite.net (HELO FTLPEX01CL01.citrite.net) ([10.9.154.239]) by FTLPIPO01.CITRIX.COM with ESMTP; 17 Sep 2013 09:26:41 +0000 Received: from norwich.cam.xci-test.com (10.80.248.129) by smtprelay.citrix.com (10.13.107.78) with Microsoft SMTP Server id 14.2.342.4; Tue, 17 Sep 2013 05:26:41 -0400 Received: from mariner.cam.xci-test.com ([10.80.2.22] helo=mariner.uk.xensource.com ident=Debian-exim) by norwich.cam.xci-test.com with esmtp (Exim 4.72) (envelope-from ) id 1VLrYO-0001fC-Te; Tue, 17 Sep 2013 09:26:40 +0000 Received: from iwj by mariner.uk.xensource.com with local (Exim 4.80) (envelope-from ) id 1VLrYO-0003VE-KR; Tue, 17 Sep 2013 10:26:40 +0100 From: Ian Jackson MIME-Version: 1.0 Message-ID: <21048.8272.465544.579024@mariner.uk.xensource.com> Date: Tue, 17 Sep 2013 10:26:40 +0100 To: George Dunlap In-Reply-To: <523811E8.6080304@eu.citrix.com> References: <523337AA.5080103@oracle.com> <5237291C.9090100@oracle.com> <21047.12251.625579.745154@mariner.uk.xensource.com> <523742B3.5040204@oracle.com> <523811E8.6080304@eu.citrix.com> X-Mailer: VM 8.1.0 under 23.4.1 (i486-pc-linux-gnu) X-DLP: MIA1 Cc: Zhigang Wang , xen-devel Subject: Re: [Xen-devel] Suggestion for merging xl save/restore/migrate/migrate-receive X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org George Dunlap writes ("Re: [Xen-devel] Suggestion for merging xl save/restore/migrate/migrate-receive"): > On 09/16/2013 06:41 PM, Zhigang Wang wrote: > > ... Also after this, all Servers in a pool can login to each > > other. I don't know whether it's a security issue for our product. > > > > This is something we try to avoid at this time. > > ...so instead of allowing anyone on one of the hosts log in, you're > going to allow anyone with access to the network to create a VM without > any kind of authentication? > > From a security perspective, that doesn't really sound like an > improvement... Note that if host B allows incoming migrations from host A, then host B is trusting host A completely. This is because the migration data contains not just the guest's state (which is of course encapsulated inside the Xen VM security boundary), but also the VM configuration. The VM configuration specifies the mapping between guest resources and host resources. So host B trusts host A to specify the correct set of host B's own resources to expose to the guest VM. If host A is malicious it can send a VM whose configuration specifies (for example) that the whole of host B's disk is to be exposed to the guest, along with a guest which will make whatever malicious changes host A desires. In summary: accepting incoming migration images is just as dangerous as allowing root login (from the same source host). So switching the transport from ssh to unauthenticated ssl makes the security against malicious migration source hosts strictly worse. The only way unauthenticated ssl is better than simply unauthenticated unencrypted TCP is protection against passive eavesdropping. This is important for much general traffic on the public Internet (see recent revelations about widespread eavesdropping), but probably not relevant for the control plane of a VM hosting setup. If your control plane network has bad people on it, you need authentication as well as encryption. So I don't think we should be adding new code to xl which might encourage the use of ssl. The proposed format-string based template would be OK, but I think really that we should have better (more convenient) support for unencrypted migration. Things that would be helpful: * An option to xl migrate which causes xl to make the TCP connection itself. This is a not-quite-trivial SMOP and the specification ought to be trivial. * A separate executable (or perhaps argv[0] mode) "xl-migrate-receive" so that the hosts.{allow,deny} etc. files used by tcpd can contain "xl-migrate-receive" and not just "xl". The specification for this would need to be discussed, but the implementation will be trivial. * A command line option for logging redirection so that /all/ the error messages from an inetd-launched xl migrate-receive go somewhere useful. The specification for this would need to be discussed, but the implementation should be very simple. * Better documentation, particularly including a recipe for setting this up, covering: inetd.conf, hosts.{allow,deny}, invocation at the sending end, security considerations. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel