From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37158) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XkDlF-0004Wh-NH for qemu-devel@nongnu.org; Fri, 31 Oct 2014 11:05:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XkAEn-00054t-94 for qemu-devel@nongnu.org; Fri, 31 Oct 2014 07:19:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39580) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XkAEn-00054L-0t for qemu-devel@nongnu.org; Fri, 31 Oct 2014 07:19:25 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s9VBJORf008355 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Fri, 31 Oct 2014 07:19:24 -0400 Date: Fri, 31 Oct 2014 11:19:22 +0000 From: Stefan Hajnoczi Message-ID: <20141031111922.GD10332@stefanha-thinkpad.redhat.com> References: <1414512220-19058-1-git-send-email-armbru@redhat.com> <1414512220-19058-3-git-send-email-armbru@redhat.com> <20141029101242.GA3719@noname.str.redhat.com> <877fzjc76v.fsf@blackfin.pond.sub.org> <20141030093040.GA9097@noname.str.redhat.com> <87oastzprh.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="4zI0WCX1RcnW9Hbu" Content-Disposition: inline In-Reply-To: <87oastzprh.fsf@blackfin.pond.sub.org> Subject: Re: [Qemu-devel] [PATCH RFC 2/2] block: Warn on insecure format probing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Kevin Wolf , jcody@redhat.com, qemu-devel@nongnu.org --4zI0WCX1RcnW9Hbu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Oct 30, 2014 at 01:49:22PM +0100, Markus Armbruster wrote: > Kevin Wolf writes: >=20 > > Am 29.10.2014 um 14:54 hat Markus Armbruster geschrieben: > >> Anthony tried something similar (commit 79368c8), but couldn't get it > >> right (commit 8b33d9e). > > > > The discussion back then: http://patchwork.ozlabs.org/patch/58980/ > > > > The problem with Anthony's code was that he didn't handle a qiov > > correctly that had unaligned members. With today's block layer, this is > > not a big deal to implement correctly. We're running coroutines instead > > of AIO callbacks and we don't have to do all the manual qiov fixing > > magic that Anthony had in his patch, util/iov.c provides all you need. > > > > I'll send out an RFC series that implements this. >=20 > I'm strongly opposed to this idea. Me too. Meddling with the guest is wrong and just adds a new problem! It is perfectly okay for backup appliances, nested virtualization, or disk management appliances to write image format headers to raw disks. I'm am 100% against trying to detect the guest writing image format headers to raw disks. Probing is not a guest problem. It is a QEMU problem. Fix QEMU, don't cripple the guest. Stefan --4zI0WCX1RcnW9Hbu Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUU3A6AAoJEJykq7OBq3PIrcEIAICgyfd6MT/4jB76IP5eiZME eJDy9bjzav+BbHacFgURuvqKuiybOl532sfImFOiz3RVgQRHhuwjN0JrQgaK83w+ XddFQC3K9hGQGe2APpVhksanM28w6iKwdMdt+jF/47k7Trn/IyNGnMViIx041HZx Ae03stOYG5C7foZuGnFtn2Bub+K7yl4zC0An77Koc4TQG10w8XUr7GEmEH8FDt5i 71CeUFSeBPpLxaYDKpU2b1HtsvplXNIECJmOqzl564PusGx9DhSICkS1a+QqsWUH X5LJKVKT9xrYY8/QJg/rIfW/ljXp7rW5jY0da3wWyXfBi5iuEOJQo/mb7capITc= =uNN1 -----END PGP SIGNATURE----- --4zI0WCX1RcnW9Hbu--