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. Max > + > + switch (fmt) { > + case QCOW_CRYPT_LUKS: > + cryptoopts = block_crypto_create_opts_init( > + Q_CRYPTO_BLOCK_FORMAT_LUKS, encryptopts, errp); > + break; > + case QCOW_CRYPT_AES: > + cryptoopts = block_crypto_create_opts_init( > + Q_CRYPTO_BLOCK_FORMAT_QCOW, encryptopts, errp); > + break; > + default: > + error_setg(errp, "Unknown encryption format '%s'", encryptfmt); > + break; > } > - cryptoopts = block_crypto_create_opts_init( > - Q_CRYPTO_BLOCK_FORMAT_QCOW, encryptopts, errp); > if (!cryptoopts) { > ret = -EINVAL; > goto out; > } > - s->crypt_method_header = QCOW_CRYPT_AES; > + s->crypt_method_header = fmt; > > crypto = qcrypto_block_create(cryptoopts, > - NULL, NULL, > + qcow2_crypto_hdr_init_func, > + qcow2_crypto_hdr_write_func, > bs, errp); > if (!crypto) { > ret = -EINVAL;
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