On 2017-06-21 16:46, Max Reitz wrote: > On 2017-06-21 16:42, Max Reitz wrote: >> On 2017-06-19 19:34, 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 <[email protected]> >>> Reviewed-by: Alberto Garcia <[email protected]> >>> Signed-off-by: Daniel P. Berrange <[email protected]> >>> --- >>> block/qcow2-cluster.c | 4 +- >>> block/qcow2-refcount.c | 10 ++ >>> block/qcow2.c | 268 >>> ++++++++++++++++++++++++++++++++++++++------ >>> block/qcow2.h | 9 ++ >>> qapi/block-core.json | 5 +- >>> tests/qemu-iotests/082.out | 270 >>> ++++++++++++++++++++++++++++++++++++--------- >>> 6 files changed, 478 insertions(+), 88 deletions(-) >> >> Reviewed-by: Max Reitz <[email protected]> > > (But due to the split of do_perform_cow(), this will need the same > changes that patch 10 and 11 will need (in this case only contextual, in > the cases of 10 and 11 there are also functional changes required).)
(Turns out it will need a functional change, too, because do_perform_cow_encrypt() doesn't take the host offset yet.) Max
signature.asc
Description: OpenPGP digital signature
