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authorDaniel P. Berrange <berrange@redhat.com>2017-06-23 17:24:12 +0100
committerMax Reitz <mreitz@redhat.com>2017-07-11 17:44:56 +0200
commit4652b8f3e1ec91bb9d6f00e40df7f96d1f1aafee (patch)
treeda90a98ee85cbc57d4e9bf61e72bf8217059d8ec /block/qcow2-refcount.c
parent7674b5754e56c0639c231619764761d8bf0bebf2 (diff)
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qcow2: add support for LUKS encryption format
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. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170623162419.26068-14-berrange@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r--block/qcow2-refcount.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 7c06061..81c22e6 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1856,6 +1856,16 @@ static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
return ret;
}
+ /* encryption */
+ if (s->crypto_header.length) {
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ s->crypto_header.offset,
+ s->crypto_header.length);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
return check_refblocks(bs, res, fix, rebuild, refcount_table, nb_clusters);
}