On Wed, Jun 07, 2017 at 07:19:28PM +0200, Max Reitz wrote:
> On 2017-06-01 19:27, Daniel P. Berrange wrote:
> > This adds support for using LUKS as an encryption format
> > with the qcow2 file, using the new encrypt.format parameter
> > to request "luks" format. e.g.
> >
> > # qemu-img create --object secret,data=123456,id=sec0 \
> > -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \
> > test.qcow2 10G
> >
> > The legacy "encryption=on" parameter still results in
> > creation of the old qcow2 AES format (and is equivalent
> > to the new 'encryption-format=aes'). e.g. the following are
> > equivalent:
> >
> > # qemu-img create --object secret,data=123456,id=sec0 \
> > -f qcow2 -o encryption=on,encrypt.key-secret=sec0 \
> > test.qcow2 10G
> >
> > # qemu-img create --object secret,data=123456,id=sec0 \
> > -f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \
> > test.qcow2 10G
> >
> > With the LUKS format it is necessary to store the LUKS
> > partition header and key material in the QCow2 file. This
> > data can be many MB in size, so cannot go into the QCow2
> > header region directly. Thus the spec defines a FDE
> > (Full Disk Encryption) header extension that specifies
> > the offset of a set of clusters to hold the FDE headers,
> > as well as the length of that region. The LUKS header is
> > thus stored in these extra allocated clusters before the
> > main image payload.
> >
> > Aside from all the cryptographic differences implied by
> > use of the LUKS format, there is one further key difference
> > between the use of legacy AES and LUKS encryption in qcow2.
> > For LUKS, the initialiazation vectors are generated using
> > the host physical sector as the input, rather than the
> > guest virtual sector. This guarantees unique initialization
> > vectors for all sectors when qcow2 internal snapshots are
> > used, thus giving stronger protection against watermarking
> > attacks.
> >
> > Reviewed-by: Eric Blake <ebl...@redhat.com>
> > Reviewed-by: Alberto Garcia <be...@igalia.com>
> > Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
> > ---
> > block/qcow2-cluster.c | 4 +-
> > block/qcow2-refcount.c | 10 ++
> > block/qcow2.c | 267
> > ++++++++++++++++++++++++++++++++++++++------
> > block/qcow2.h | 9 ++
> > qapi/block-core.json | 5 +-
> > tests/qemu-iotests/082.out | 270
> > ++++++++++++++++++++++++++++++++++++---------
> > 6 files changed, 477 insertions(+), 88 deletions(-)
>
> [...]
>
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 38c0420..30d0343 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
>
> [...]
>
> > @@ -2072,22 +2253,30 @@ static int qcow2_set_up_encryption(BlockDriverState
> > *bs, const char *encryptfmt,
> > qdict_extract_subqdict(options, &encryptopts, "encrypt.");
> > QDECREF(options);
> >
> > - if (!g_str_equal(encryptfmt, "aes")) {
> > - error_setg(errp, "Unknown encryption format '%s', expected 'aes'",
> > - encryptfmt);
> > - ret = -EINVAL;
> > - goto out;
> > + int fmt = qcow2_crypt_method_from_format(encryptfmt);
>
> Because I love nit picking: Variable declarations should be at the start
> of the surrounding block.
Opps, dunno what I was thinking there.
Regards,
Daniel
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