From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756402Ab2CUQHb (ORCPT ); Wed, 21 Mar 2012 12:07:31 -0400 Received: from mga02.intel.com ([134.134.136.20]:44786 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755373Ab2CUQH3 (ORCPT ); Wed, 21 Mar 2012 12:07:29 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="asc'?scan'208";a="120052547" Message-ID: <1332346218.14983.20.camel@sauron.fi.intel.com> Subject: Re: [patch] Add design document for UBIFS secure deletion From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Joel Reardon Cc: linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 21 Mar 2012 18:10:18 +0200 In-Reply-To: References: <1329152067.22240.214.camel@sauron.fi.intel.com> <1331277476.22872.2.camel@sauron.fi.intel.com> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-m3outrbS+1ACkzWMD0gC" X-Mailer: Evolution 3.2.3 (3.2.3-1.fc16) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-m3outrbS+1ACkzWMD0gC Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2012-03-19 at 17:54 +0100, Joel Reardon wrote: > Design document should be self explanatory. >=20 > Signed-off-by: Joel Reardon >=20 > --- > Documentation/filesystems/ubifsec.txt | 358 +++++++++++++++++++++++++++= ++++++ > 1 files changed, 358 insertions(+), 0 deletions(-) > create mode 100644 Documentation/filesystems/ubifsec.txt >=20 > diff --git a/Documentation/filesystems/ubifsec.txt b/Documentation/filesy= stems/ubifsec.txt > new file mode 100644 > index 0000000..4eb41fb > --- /dev/null > +++ b/Documentation/filesystems/ubifsec.txt > @@ -0,0 +1,357 @@ > +UBIFS Secure Deletion Enhancement > + > +Written by Joel Reardon > +Last revised: 19.3.2012 > + > +Introduction > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > +UBIFSec provides efficient secure deletion for the flash file system UBI= FS. > +Trivial secure deletion by overwriting the deleted data does not work fo= r > +flash memory, as there is a large difference between the size of the I/O= unit > +(page) and the erasure unit (erase block). I think for correctness you should use term "LEB" everywhere, not "eraseblock". > UBIFSec encrypts each data node > +with a distinct key and stores the keys colocated in a key storage area = (KSA). > +Secure deletion is achieved by atomically updating the (small) set of er= ase > +blocks that constitute the KSA to remove keys corresponding to deleted d= ata, > +thereby deleting the data nodes they encrypted. > + > +Key Storage Area (KSA) > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > +UBIFSec uses a small migrating set of erase blocks to store all the data "Migrating" set? To me it sounds like the KSA area changes the position withing the UBI volume. I'd suggest to remove word "migrating". > +node's keys---this set is called the Key Storage Area (KSA). The KSA is > +managed separately from the rest of the file system. In particular, it d= oes > +not behave like a log-structured file system: when a KSA erase block is > +updated, its contents are written to a new erase block s/to a new erase block/to a new KSA LEB/ ? > , the logical reference > +to the KSA block is updated, and the previous version of the KSA erase b= lock s/KSA block/KSA LEB/ ? Also, it is not clear what is the "logical reference" - would be nice to probably introduce this notion before using it. --=20 Best Regards, Artem Bityutskiy --=-m3outrbS+1ACkzWMD0gC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAABAgAGBQJPaf1qAAoJECmIfjd9wqK0V7QP+gMBaQVhy5vWNKJWLQU5OeJC LzwQisDFvcXq2SRj9TG/Ml4ZdVtR/Byk83DjKC3pnZtVeQFYMb60N8N9DcH3FFeH pK8S2g/cEAe2PWAzASmaF8CxGeaQTS/tV0mfKDMfTotpVkGyaauEbxxFWD8ZNKW0 YIq0xcNbTf6HfO6H2YdxjFrEPG4DBm1EUwnmROlyZQhIyvzDal/vAFKqW7Jk7xgY 7buaf4y6YS+ZBsHF57O+j3W048KTxUlnxWcfxylo8Yx/qC7vYtmKpehMaUrPfIQR GJjx4Y541X+AyGf4HN4MnnAcHAV3PL6/Zh3+VjoqLOFDdDq3d9oS7rYZYI3MiR5n DuRTNTd1A0XtEiZiFuwebpaMM6ywadO5ZmXGPjrLUGSOpsa4q8ocaFudQgdMMJ8M vxRS9l4QB069E7qs2b0lkDuKJic89FWU/CgeP1FrEtc4ZYSdrz7Nvri1H3dXBsHr nZ114EnkqkFhgyZtkBn9xVURAqfz7U5sPAlx5lJG/bYU9dBMRIwLuy8NwLqfu8Ci bLEsD12zKxqFW+XHte+Axqm73VQtIP6YjZUPk1PXubojIDzKMKgN/m1o4QraX4vK WaYyjbdqGQNCap6tjVrgci/O9p9hV0WgTMF0TksxYhvcEDJqBYHlA4CGxqS3uX7g a9K0Th9hWUNqWTum5shg =RXua -----END PGP SIGNATURE----- --=-m3outrbS+1ACkzWMD0gC--