Re: [libvirt] [PATCH 14/19] conf: Add new secret type "key"
On 06/21/2016 08:08 AM, Peter Krempa wrote:
On Mon, Jun 13, 2016 at 20:27:53 -0400, John Ferlan wrote:
> Add a new secret type known as "key" - it will handle adding the secret
> objects that need a key (or passphrase), such as will soon be the case
This may be misleading a "key" is not equal to a "passprhase" in
usual
encryption terminology. Key usually refers to the actual encryption key
used to encrypt the data whereas passprhase is usually a human readable
secret string (which may not be random at all) used to access the key
later.
The cryptsetup man page tends to treat them interchangably to some
extent (eg a key slot equals to passprhase, but the master key refers to
the actual encryption key used for the data).
To avoid confusion I'd rather stick with "passphrase".
> for a luks volume for both storage driver create and libvirt domain usage.
>
> Signed-off-by: John Ferlan <jferlan(a)redhat.com>
> ---
While replying to review comments from 6/19, I realized another reason I
went with "key" over "passphrase".
Consider the existing/old qcow encryption format
(http://libvirt.org/formatsecret.html)
The <secret> XML looks like:
<secret ephemeral='no' private='yes'>
<description>Super secret name of my first puppy</description>
<uuid>0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f</uuid>
<usage type='volume'>
<volume>/var/lib/libvirt/images/puppyname.img</volume>
</usage>
</secret>
while the <domain> XML has:
<encryption format='qcow'>
<secret type='passphrase'
uuid='0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f'/>
</encryption>
or once patch 11 hits:
<encryption format='qcow'>
<secret type='passphrase'
usage='/var/lib/libvirt/images/puppyname.img'/>
</encryption>
where 'usage' matches 'volume'
Using something other than passphrase allowed me to distinguish between
that 'old' format and this new style...
Using "passphrase" will then have <domain> format of:
<encryption format='luks'>
<secret type='passphrase' {uuid|usage}='...'>/
And a <secret> format of
<secret ephemeral='no' private='yes'>
<description>Sample</description>
<uuid>0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f</uuid>
<usage type='passphrase'>
<passphrase>somestring</passphrase>
</usage>
</secret>
where "somestring" is just a 'usage' string and not the actual
passphrase which would be set by the 'secret-set-value' command.
I could have the <secret> XML use something different than passphrase,
but key just seemed to be the most reasonable beyond passphrase. Unless
you have a different suggestion for a better name.
John
Hopefully this was clear...