From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37734) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xlxhm-0003Rc-CH for qemu-devel@nongnu.org; Wed, 05 Nov 2014 05:20:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xlxhb-0003zL-Ab for qemu-devel@nongnu.org; Wed, 05 Nov 2014 05:20:46 -0500 Received: from resqmta-po-10v.sys.comcast.net ([2001:558:fe16:19:96:114:154:169]:40182) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xlxhb-0003yh-4X for qemu-devel@nongnu.org; Wed, 05 Nov 2014 05:20:35 -0500 Message-ID: <5459F961.8030305@redhat.com> Date: Wed, 05 Nov 2014 11:18:09 +0100 From: Eric Blake MIME-Version: 1.0 References: <87lhnq3iul.fsf@blackfin.pond.sub.org> <5459E210.2020008@redhat.com> In-Reply-To: <5459E210.2020008@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Sm5085qRrxfElAj6eRKAug9N8eAiBvsF9" Subject: Re: [Qemu-devel] Image probing: how it can be insecure, and what we could do about it List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , Markus Armbruster , qemu-devel@nongnu.org Cc: Kevin Wolf , Jeff Cody , Stefan Hajnoczi This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Sm5085qRrxfElAj6eRKAug9N8eAiBvsF9 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 11/05/2014 09:38 AM, Max Reitz wrote: >> Note that specifying just the top image's format is not enough, you al= so >> have to specify any backing images' formats. QCOW2 can optionally sto= re >> the backing image format in the image. The other COW formats can't. >=20 > Well, they can, with "json:". *cough* >=20 >> Example of insecure usage: -hda bar.vmdk, where bar.vmdk is a VMDK ima= ge >> with a raw backing file. >=20 > Yesterday I found out that doesn't seem possible. You apparently can > only use VMDK with VMDK backing files. Other than that, we only have > qcow1 and qed as COW formats which should not be used anyway. Actually, qed requires the backing format to be recorded (it is non-optional) and is therefore immune to probing problems of backing files. That's one thing it got right. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --Sm5085qRrxfElAj6eRKAug9N8eAiBvsF9 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg iQEcBAEBCAAGBQJUWflhAAoJEKeha0olJ0NqmzIH/2MynQEYgnLWCL7D7ys7MF/r D4KCTfSoiibyKvAELzJy9cOsR8jAAqbkgj6I9bvdaeRxJQkXD9QAKXaoCBwzjfoH +KRsPi0/xHY6hBwNMOX0Mht15P66P70oWX78UpwMGrC2gvnjrH7DK2gFxkZ4pnE8 lrvbqBjTA774vJTqe4OMsMYcJJvFgOqTcyUtzSJGDwYa1ZYKVCHqRW09kxr/AWF7 rxS5XZvK4pXPp3b8KCULv5BEpQEJMjbTouYIh35YcLf7C2vamqVQdcPiEkAw5Mkm MEQl2beAR8rjonbMyqIv5VORxqtuNiJBwqT2i9H4trtPISOoapFgUJxiXt7KRVc= =eIgU -----END PGP SIGNATURE----- --Sm5085qRrxfElAj6eRKAug9N8eAiBvsF9--