By enhancing the LUKS driver, it is possible to enable
the detachable LUKS header and, as a result, achieve
general encryption for any disk format that QEMU has
supported.
Take the qcow2 as an example, the usage of the generic
LUKS encryption as follows:
1. add a protocol blockdev node of data disk
$ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> "arguments":{"node-name":"libvirt-1-storage", "driver":"file",
> "filename":"/path/to/test_disk.qcow2"}}'
2. add a protocol blockdev node of LUKS header as above.
$ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> "arguments":{"node-name":"libvirt-2-storage", "driver":"file",
> "filename": "/path/to/cipher.gluks" }}'
3. add the secret for decrypting the cipher stored in LUKS
header above
$ virsh qemu-monitor-command vm '{"execute":"object-add",
> "arguments":{"qom-type":"secret", "id":
> "libvirt-2-storage-secret0", "data":"abc123"}}'
4. add the qcow2-drived blockdev format node
$ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> "arguments":{"node-name":"libvirt-1-format", "driver":"qcow2",
> "file":"libvirt-1-storage"}}'
5. add the luks-drived blockdev to link the qcow2 disk with
LUKS header by specifying the field "header"
$ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> "arguments":{"node-name":"libvirt-2-format", "driver":"luks",
> "file":"libvirt-1-format", "header":"libvirt-2-storage",
> "key-secret":"libvirt-2-format-secret0"}}'
6. add the virtio-blk device finally
$ virsh qemu-monitor-command vm '{"execute":"device_add",
> "arguments": {"num-queues":"1", "driver":"virtio-blk-pci",
> "drive": "libvirt-2-format", "id":"virtio-disk2"}}'
The generic LUKS encryption method of starting a virtual
machine (VM) is somewhat similar to hot-plug in that both
maintaining the same json command while the starting VM
changes the "blockdev-add/device_add" parameters to
"blockdev/device".
Signed-off-by: Hyman Huang <yong.huang@smartx.com>
---
block/crypto.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/block/crypto.c b/block/crypto.c
index f82b13d32b..7d70349463 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -40,6 +40,7 @@ struct BlockCrypto {
QCryptoBlock *block;
bool updating_keys;
BdrvChild *header; /* Reference to the detached LUKS header */
+ bool detached_mode; /* If true, LUKS plays a detached header role */
};
@@ -64,12 +65,16 @@ static int block_crypto_read_func(QCryptoBlock *block,
Error **errp)
{
BlockDriverState *bs = opaque;
+ BlockCrypto *crypto = bs->opaque;
ssize_t ret;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
- ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
+ if (crypto->detached_mode)
+ ret = bdrv_pread(crypto->header, offset, buflen, buf, 0);
+ else
+ ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read encryption header");
return ret;
@@ -269,6 +274,8 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
QCryptoBlockOpenOptions *open_opts = NULL;
unsigned int cflags = 0;
QDict *cryptoopts = NULL;
+ const char *header_bdref =
+ qdict_get_try_str(options, "header");
GLOBAL_STATE_CODE();
@@ -277,6 +284,16 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
return ret;
}
+ if (header_bdref) {
+ crypto->detached_mode = true;
+ crypto->header = bdrv_open_child(NULL, options, "header", bs,
+ &child_of_bds, BDRV_CHILD_METADATA,
+ false, errp);
+ if (!crypto->header) {
+ return -EINVAL;
+ }
+ }
+
GRAPH_RDLOCK_GUARD_MAINLOOP();
bs->supported_write_flags = BDRV_REQ_FUA &
@@ -312,6 +329,14 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
goto cleanup;
}
+ if (crypto->detached_mode) {
+ /*
+ * Set payload offset to zero as the file bdref has no LUKS
+ * header under detached mode.
+ */
+ qcrypto_block_set_payload_offset(crypto->block, 0);
+ }
+
bs->encrypted = true;
ret = 0;
@@ -903,6 +928,17 @@ block_crypto_child_perms(BlockDriverState *bs, BdrvChild *c,
BlockCrypto *crypto = bs->opaque;
+ if (role == (role & BDRV_CHILD_METADATA)) {
+ /* Assign read permission only */
+ perm |= BLK_PERM_CONSISTENT_READ;
+ /* Share all permissions */
+ shared |= BLK_PERM_ALL;
+
+ *nperm = perm;
+ *nshared = shared;
+ return;
+ }
+
bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared);
/*
--
2.39.1On Thu, Dec 07, 2023 at 12:37:44AM +0800, Hyman Huang wrote:
> By enhancing the LUKS driver, it is possible to enable
> the detachable LUKS header and, as a result, achieve
> general encryption for any disk format that QEMU has
> supported.
>
> Take the qcow2 as an example, the usage of the generic
> LUKS encryption as follows:
>
> 1. add a protocol blockdev node of data disk
> $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > "arguments":{"node-name":"libvirt-1-storage", "driver":"file",
> > "filename":"/path/to/test_disk.qcow2"}}'
>
> 2. add a protocol blockdev node of LUKS header as above.
> $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > "arguments":{"node-name":"libvirt-2-storage", "driver":"file",
> > "filename": "/path/to/cipher.gluks" }}'
>
> 3. add the secret for decrypting the cipher stored in LUKS
> header above
> $ virsh qemu-monitor-command vm '{"execute":"object-add",
> > "arguments":{"qom-type":"secret", "id":
> > "libvirt-2-storage-secret0", "data":"abc123"}}'
>
> 4. add the qcow2-drived blockdev format node
> $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > "arguments":{"node-name":"libvirt-1-format", "driver":"qcow2",
> > "file":"libvirt-1-storage"}}'
>
> 5. add the luks-drived blockdev to link the qcow2 disk with
> LUKS header by specifying the field "header"
> $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > "arguments":{"node-name":"libvirt-2-format", "driver":"luks",
> > "file":"libvirt-1-format", "header":"libvirt-2-storage",
> > "key-secret":"libvirt-2-format-secret0"}}'
>
> 6. add the virtio-blk device finally
> $ virsh qemu-monitor-command vm '{"execute":"device_add",
> > "arguments": {"num-queues":"1", "driver":"virtio-blk-pci",
> > "drive": "libvirt-2-format", "id":"virtio-disk2"}}'
>
> The generic LUKS encryption method of starting a virtual
> machine (VM) is somewhat similar to hot-plug in that both
> maintaining the same json command while the starting VM
> changes the "blockdev-add/device_add" parameters to
> "blockdev/device".
>
> Signed-off-by: Hyman Huang <yong.huang@smartx.com>
> ---
> block/crypto.c | 38 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/block/crypto.c b/block/crypto.c
> index f82b13d32b..7d70349463 100644
> --- a/block/crypto.c
> +++ b/block/crypto.c
> @@ -40,6 +40,7 @@ struct BlockCrypto {
> QCryptoBlock *block;
> bool updating_keys;
> BdrvChild *header; /* Reference to the detached LUKS header */
> + bool detached_mode; /* If true, LUKS plays a detached header role */
> };
>
>
> @@ -64,12 +65,16 @@ static int block_crypto_read_func(QCryptoBlock *block,
> Error **errp)
> {
> BlockDriverState *bs = opaque;
> + BlockCrypto *crypto = bs->opaque;
> ssize_t ret;
>
> GLOBAL_STATE_CODE();
> GRAPH_RDLOCK_GUARD_MAINLOOP();
>
> - ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
> + if (crypto->detached_mode)
> + ret = bdrv_pread(crypto->header, offset, buflen, buf, 0);
> + else
> + ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
This can be simplified to:
ret = bdrv_pread(bs->header ? bs->header : file, offset, buflen, buf, 0);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "Could not read encryption header");
> return ret;
> @@ -269,6 +274,8 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
> QCryptoBlockOpenOptions *open_opts = NULL;
> unsigned int cflags = 0;
> QDict *cryptoopts = NULL;
> + const char *header_bdref =
> + qdict_get_try_str(options, "header");
>
> GLOBAL_STATE_CODE();
>
> @@ -277,6 +284,16 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
> return ret;
> }
>
> + if (header_bdref) {
> + crypto->detached_mode = true;
Drop this flag since it has no benefit.
> + crypto->header = bdrv_open_child(NULL, options, "header", bs,
> + &child_of_bds, BDRV_CHILD_METADATA,
> + false, errp);
> + if (!crypto->header) {
> + return -EINVAL;
> + }
> + }
> +
> GRAPH_RDLOCK_GUARD_MAINLOOP();
>
> bs->supported_write_flags = BDRV_REQ_FUA &
> @@ -312,6 +329,14 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
> goto cleanup;
> }
>
> + if (crypto->detached_mode) {
if (crypto->header != NULL)
> + /*
> + * Set payload offset to zero as the file bdref has no LUKS
> + * header under detached mode.
> + */
> + qcrypto_block_set_payload_offset(crypto->block, 0);
The LUKS header stores the payload offset. If someone creates the LUKS
volume with a detached header, they may still choose to put the payload
at a non-zero offset.
So AFAICT, we should always honour the payload offset from the header,
even when detached. When formatting the header, we should default to
a zero offset though
> + }
> +
> bs->encrypted = true;
>
> ret = 0;
> @@ -903,6 +928,17 @@ block_crypto_child_perms(BlockDriverState *bs, BdrvChild *c,
>
> BlockCrypto *crypto = bs->opaque;
>
> + if (role == (role & BDRV_CHILD_METADATA)) {
> + /* Assign read permission only */
> + perm |= BLK_PERM_CONSISTENT_READ;
> + /* Share all permissions */
> + shared |= BLK_PERM_ALL;
> +
> + *nperm = perm;
> + *nshared = shared;
> + return;
> + }
What is code doing ? You've set BDRV_CHILD_METADATA role on the
crypto->header object, but how does this block_crypto_child_perms
method get run against crypto->header ?
> +
> bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared);
>
> /*
> --
> 2.39.1
>
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On Mon, Dec 18, 2023 at 7:16 PM Daniel P. Berrangé <berrange@redhat.com>
wrote:
> On Thu, Dec 07, 2023 at 12:37:44AM +0800, Hyman Huang wrote:
> > By enhancing the LUKS driver, it is possible to enable
> > the detachable LUKS header and, as a result, achieve
> > general encryption for any disk format that QEMU has
> > supported.
> >
> > Take the qcow2 as an example, the usage of the generic
> > LUKS encryption as follows:
> >
> > 1. add a protocol blockdev node of data disk
> > $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > > "arguments":{"node-name":"libvirt-1-storage", "driver":"file",
> > > "filename":"/path/to/test_disk.qcow2"}}'
> >
> > 2. add a protocol blockdev node of LUKS header as above.
> > $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > > "arguments":{"node-name":"libvirt-2-storage", "driver":"file",
> > > "filename": "/path/to/cipher.gluks" }}'
> >
> > 3. add the secret for decrypting the cipher stored in LUKS
> > header above
> > $ virsh qemu-monitor-command vm '{"execute":"object-add",
> > > "arguments":{"qom-type":"secret", "id":
> > > "libvirt-2-storage-secret0", "data":"abc123"}}'
> >
> > 4. add the qcow2-drived blockdev format node
> > $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > > "arguments":{"node-name":"libvirt-1-format", "driver":"qcow2",
> > > "file":"libvirt-1-storage"}}'
> >
> > 5. add the luks-drived blockdev to link the qcow2 disk with
> > LUKS header by specifying the field "header"
> > $ virsh qemu-monitor-command vm '{"execute":"blockdev-add",
> > > "arguments":{"node-name":"libvirt-2-format", "driver":"luks",
> > > "file":"libvirt-1-format", "header":"libvirt-2-storage",
> > > "key-secret":"libvirt-2-format-secret0"}}'
> >
> > 6. add the virtio-blk device finally
> > $ virsh qemu-monitor-command vm '{"execute":"device_add",
> > > "arguments": {"num-queues":"1", "driver":"virtio-blk-pci",
> > > "drive": "libvirt-2-format", "id":"virtio-disk2"}}'
> >
> > The generic LUKS encryption method of starting a virtual
> > machine (VM) is somewhat similar to hot-plug in that both
> > maintaining the same json command while the starting VM
> > changes the "blockdev-add/device_add" parameters to
> > "blockdev/device".
> >
> > Signed-off-by: Hyman Huang <yong.huang@smartx.com>
> > ---
> > block/crypto.c | 38 +++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 37 insertions(+), 1 deletion(-)
> >
> > diff --git a/block/crypto.c b/block/crypto.c
> > index f82b13d32b..7d70349463 100644
> > --- a/block/crypto.c
> > +++ b/block/crypto.c
> > @@ -40,6 +40,7 @@ struct BlockCrypto {
> > QCryptoBlock *block;
> > bool updating_keys;
> > BdrvChild *header; /* Reference to the detached LUKS header */
> > + bool detached_mode; /* If true, LUKS plays a detached header role */
> > };
> >
> >
> > @@ -64,12 +65,16 @@ static int block_crypto_read_func(QCryptoBlock
> *block,
> > Error **errp)
> > {
> > BlockDriverState *bs = opaque;
> > + BlockCrypto *crypto = bs->opaque;
> > ssize_t ret;
> >
> > GLOBAL_STATE_CODE();
> > GRAPH_RDLOCK_GUARD_MAINLOOP();
> >
> > - ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
> > + if (crypto->detached_mode)
> > + ret = bdrv_pread(crypto->header, offset, buflen, buf, 0);
> > + else
> > + ret = bdrv_pread(bs->file, offset, buflen, buf, 0);
>
> This can be simplified to:
>
> ret = bdrv_pread(bs->header ? bs->header : file, offset, buflen, buf,
> 0);
>
Ok.
>
> > if (ret < 0) {
> > error_setg_errno(errp, -ret, "Could not read encryption
> header");
> > return ret;
> > @@ -269,6 +274,8 @@ static int
> block_crypto_open_generic(QCryptoBlockFormat format,
> > QCryptoBlockOpenOptions *open_opts = NULL;
> > unsigned int cflags = 0;
> > QDict *cryptoopts = NULL;
> > + const char *header_bdref =
> > + qdict_get_try_str(options, "header");
> >
> > GLOBAL_STATE_CODE();
> >
> > @@ -277,6 +284,16 @@ static int
> block_crypto_open_generic(QCryptoBlockFormat format,
> > return ret;
> > }
> >
> > + if (header_bdref) {
> > + crypto->detached_mode = true;
>
> Drop this flag since it has no benefit.
>
> > + crypto->header = bdrv_open_child(NULL, options, "header", bs,
> > + &child_of_bds,
> BDRV_CHILD_METADATA,
> > + false, errp);
> > + if (!crypto->header) {
> > + return -EINVAL;
> > + }
> > + }
> > +
> > GRAPH_RDLOCK_GUARD_MAINLOOP();
> >
> > bs->supported_write_flags = BDRV_REQ_FUA &
> > @@ -312,6 +329,14 @@ static int
> block_crypto_open_generic(QCryptoBlockFormat format,
> > goto cleanup;
> > }
> >
> > + if (crypto->detached_mode) {
>
> if (crypto->header != NULL)
>
> > + /*
> > + * Set payload offset to zero as the file bdref has no LUKS
> > + * header under detached mode.
> > + */
> > + qcrypto_block_set_payload_offset(crypto->block, 0);
>
> The LUKS header stores the payload offset. If someone creates the LUKS
> volume with a detached header, they may still choose to put the payload
> at a non-zero offset.
>
> So AFAICT, we should always honour the payload offset from the header,
> even when detached. When formatting the header, we should default to
> a zero offset though
>
Agree, I'll code in that way in the next version.
>
> > + }
> > +
> > bs->encrypted = true;
> >
> > ret = 0;
> > @@ -903,6 +928,17 @@ block_crypto_child_perms(BlockDriverState *bs,
> BdrvChild *c,
> >
> > BlockCrypto *crypto = bs->opaque;
> >
> > + if (role == (role & BDRV_CHILD_METADATA)) {
> > + /* Assign read permission only */
> > + perm |= BLK_PERM_CONSISTENT_READ;
> > + /* Share all permissions */
> > + shared |= BLK_PERM_ALL;
> > +
> > + *nperm = perm;
> > + *nshared = shared;
> > + return;
> > + }
>
> What is code doing ? You've set BDRV_CHILD_METADATA role on the
> crypto->header object, but how does this block_crypto_child_perms
> method get run against crypto->header ?
>
This paragraph originally aims to provide a function that multiple disks
could share
the same LUKS header (with read-only permission).
But I've found that it may not work when updating the detached header after
reviewing the patch recently :(.
Should it be a separate commit, Since it kind of has nothing to do with the
basic
function?
> > patchset.
>
> > +
> > bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm,
> nshared);
> >
> > /*
> > --
> > 2.39.1
> >
>
> With regards,
> Daniel
> --
> |: https://berrange.com -o-
> https://www.flickr.com/photos/dberrange :|
> |: https://libvirt.org -o-
> https://fstop138.berrange.com :|
> |: https://entangle-photo.org -o-
> https://www.instagram.com/dberrange :|
>
>
--
Best regards
On Mon, Dec 18, 2023 at 10:15:34PM +0800, Yong Huang wrote:
> On Mon, Dec 18, 2023 at 7:16 PM Daniel P. Berrangé <berrange@redhat.com>
> wrote:
> > > @@ -903,6 +928,17 @@ block_crypto_child_perms(BlockDriverState *bs,
> > BdrvChild *c,
> > >
> > > BlockCrypto *crypto = bs->opaque;
> > >
> > > + if (role == (role & BDRV_CHILD_METADATA)) {
> > > + /* Assign read permission only */
> > > + perm |= BLK_PERM_CONSISTENT_READ;
> > > + /* Share all permissions */
> > > + shared |= BLK_PERM_ALL;
> > > +
> > > + *nperm = perm;
> > > + *nshared = shared;
> > > + return;
> > > + }
> >
> > What is code doing ? You've set BDRV_CHILD_METADATA role on the
> > crypto->header object, but how does this block_crypto_child_perms
> > method get run against crypto->header ?
> >
> This paragraph originally aims to provide a function that multiple disks
> could share
> the same LUKS header (with read-only permission).
> But I've found that it may not work when updating the detached header after
> reviewing the patch recently :(.
>
> Should it be a separate commit, Since it kind of has nothing to do with the
> basic
> function?
Yes, that would be better as a separate commit.
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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