Re: [Qemu-devel] [PATCH v4 19/26] block: add generic full disk encryption driver

[Daniel P. Berrange]

On Tue, Mar 15, 2016 at 07:59:19AM -0600, Eric Blake wrote:
> On 02/29/2016 05:00 AM, Daniel P. Berrange wrote:
> > Add a block driver that is capable of supporting any full disk
> > encryption format. This utilizes the previously added block
> > encryption code, and at this time supports the LUKS format.
> > 
> > The driver code is capable of supporting any format supported
> > by the QCryptoBlock module, so it registers one block driver
> > for each format.
> > 
> > At this time, the "luks" driver is registered. New LUKS
> > compatible volume can be formatted using qemu-img with
> > defaults for all settings.
> 
> Sounds a bit redundant between the 1st and 3rd paragraph; but I'm not
> sure if I have any suggestions on shortening it for only a single
> mention that LUKS is the first (and so far only) supported driver.
> 
> > 
> > $ qemu-img create --object secret,data=123456,id=sec0 \
> >       -f luks -o key-secret=sec0 demo.luks 10G
> > 
> > Alternatively the cryptographic settings can explicitly
> > set
> > 
> > $ qemu-img create --object secret,data=123456,id=sec0 \
> >       -f luks -o key-secret=sec0,cipher-alg=aes-256,\
> >                  cipher-mode=cbc,ivgen-alg=plain64,hash-alg=sha256 \
> >       demo.luks 10G
> > 
> > And query its size
> > 
> > $ qemu-img info demo.img
> > image: demo.img
> > file format: luks
> > virtual size: 10G (10737418240 bytes)
> > disk size: 132K
> > encrypted: yes
> > 
> > Note that it was not neccessary to provide the password
> 
> s/neccessary/necessary/
> 
> > when querying info for the volume. The password is only
> > required when performing I/O on the volume
> > 
> > All volumes created by this new 'luks' driver should be
> > capable of being opened by the kernel dm-crypt driver.
> > 
> > The only algorithms listed in the LUKS spec that are
> > not currently supported by this impl are sha512 and
> > ripemd160 hashes and cast6 cipher.
> > 
> > A new I/O test is added which is used to validate the
> > interoperability of the QEMU implementation of LUKS,
> > with the dm-crypt/cryptsetup implementation. Due to
> > the need to run cryptsetup as root, this test requires
> > that the user have password-less sudo configured.
> 
> and therefore, the test better not be run by default, but by an explicit
> target.  Worth spelling out what that target is? [1]

Yes, for reference it is

  cd tests/qemu-iotests
  ./check -luks 146

...and then wait a long time :-)

In theory the other pre-existing I/O tests should also pass, but the
current I/O test infrastructure isn't clever enough to provide the
key secrets needed when creating the images. I'll be working on fixing
this test suite limitation later...

Regards,
Daniel
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