From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: RAM security Date: Mon, 06 Dec 2010 08:26:34 -0800 Message-ID: References: <4CFD02D5.7080903@abpni.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4CFD02D5.7080903@abpni.co.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jonathan Tripathy , George Dunlap , Xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 06/12/2010 07:35, "Jonathan Tripathy" wrote: > Just a few questions: >=20 > 1) By saying "the guest's responsibility", does this mean that > CONFIG_XEN_SCRUB_PAGES=3Dy is set in the DomU kernel config? Yes. > 2) Also, if a DomU was shutdown by xm destroy, obviously the DomU > wouldn=B9t scrub the RAM. However would Xen still scrub the RAM? Xen always scrubs memory on behalf of a dead domain. > 3) If the physical server was shutdown (e.g. plug pulled), I'm guessing > this will presetn a problem? Xen scrubs all memory during boot, unless told not to via a boot parameter. > 4) Why doesn't Xen scrub the RAM before giving it to the DomU? It does in the above circumstances. Otherwise it is up to the domU, and why not. -- Keir > Thanks >=20 > On 06/12/10 14:49, George Dunlap wrote: >> I looked into this sometime this last year. I believe the answer is >> "no": the domain destruction routines will zero memory before handing >> it back to Xen. >>=20 >> One potential data leak, however (last time I looked at this), is that >> Xen does not scrub memory handed back by the balloon driver. So if >> the guest OS hasn't scrubbed it, and it contains sensitive >> information, it may end up being assigned to another domain as-is >> (either via ballooning or start-of-day domain creation). At the >> moment that's considered the guest's responsibility. >>=20 >> -George >>=20 >> On Mon, Dec 6, 2010 at 2:35 PM, Jonathan Tripathy w= rote: >>> Hi Everyone, >>>=20 >>> In Xen, is a DomU able to access data in RAM which a previous DomU has >>> stored in the past, but didn't "zero" it? >>>=20 >>> I understand that this is a problem with physical disks (using phy:/), = just >>> wondering if the same stands with RAM >>>=20 >>> Thanks >>>=20 >>> _______________________________________________ >>> Xen-devel mailing list >>> Xen-devel@lists.xensource.com >>> http://lists.xensource.com/xen-devel >>>=20 >>>=20 >=20 > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel