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libvirt/docs/formatsecret.html.in
John Ferlan 8f83af6823 storage: Disallow create/resize of qcow2 encrypted images
https://bugzilla.redhat.com/show_bug.cgi?id=1526382

Since commit c4eedd793 disallowed qcow2 encrypted images to be
used for domains, it no longer makes sense to allow a qcow2
encrypted volume to be created or resized.

Add a test that will exhibit the failure of creation as well
as the xml2xml validation of the format still being correct.

Update the documentation to note the removal of the capability
to create and use qcow/default encrypted volumes.

Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>
2018-06-26 14:02:43 -04:00

331 lines
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XML

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<body>
<h1>Secret XML format</h1>
<ul id="toc"></ul>
<h2><a id="SecretAttributes">Secret XML</a></h2>
<p>
Secrets stored by libvirt may have attributes associated with them, using
the <code>secret</code> element. The <code>secret</code> element has two
optional attributes, each with values '<code>yes</code>' and
'<code>no</code>', and defaulting to '<code>no</code>':
</p>
<dl>
<dt><code>ephemeral</code></dt>
<dd>This secret must only be kept in memory, never stored persistently.
</dd>
<dt><code>private</code></dt>
<dd>The value of the secret must not be revealed to any caller of libvirt,
nor to any other node.
</dd>
</dl>
<p>
The top-level <code>secret</code> element may contain the following
elements:
</p>
<dl>
<dt><code>uuid</code></dt>
<dd>
An unique identifier for this secret (not necessarily in the UUID
format). If omitted when defining a new secret, a random UUID is
generated.
</dd>
<dt><code>description</code></dt>
<dd>A human-readable description of the purpose of the secret.
</dd>
<dt><code>usage</code></dt>
<dd>
Specifies what this secret is used for. A mandatory
<code>type</code> attribute specifies the usage category, currently
only <code>volume</code>, <code>ceph</code>, <code>iscsi</code>,
and <code>tls</code> are defined. Specific usage categories
are described below.
</dd>
</dl>
<h3><a id="VolumeUsageType">Usage type "volume"</a></h3>
<p>
This secret is associated with a volume, whether the format is either
for a "luks" encrypted volume. Each volume will have a
unique secret associated with it and it is safe to delete the
secret after the volume is deleted. The
<code>&lt;usage type='volume'&gt;</code> element must contain a
single <code>volume</code> element that specifies the path of the volume
this secret is associated with. For example, create a volume-secret.xml
file as follows:
</p>
<pre>
&lt;secret ephemeral='no' private='yes'&gt;
&lt;description&gt;Super secret name of my first puppy&lt;/description&gt;
&lt;uuid&gt;0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f&lt;/uuid&gt;
&lt;usage type='volume'&gt;
&lt;volume&gt;/var/lib/libvirt/images/puppyname.img&lt;/volume&gt;
&lt;/usage&gt;
&lt;/secret&gt;
</pre>
<p>
Define the secret and set the passphrase as follows:
</p>
<pre>
# virsh secret-define volume-secret.xml
Secret 0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f created
#
# MYSECRET=`printf %s "open sesame" | base64`
# virsh secret-set-value 0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f $MYSECRET
Secret value set
#
</pre>
<p>
The volume type secret can be supplied either in volume XML during
creation of a <a href="formatstorage.html#StorageVol">storage volume</a>
in order to provide the passphrase to encrypt the volume or in
domain XML <a href="formatdomain.html#elementsDisks">disk device</a>
in order to provide the passphrase to decrypt the volume,
<span class="since">since 2.1.0</span>. An example follows:
</p>
<pre>
# cat luks-secret.xml
&lt;secret ephemeral='no' private='yes'&gt;
&lt;description&gt;LUKS Sample Secret&lt;/description&gt;
&lt;uuid&gt;f52a81b2-424e-490c-823d-6bd4235bc57&lt;/uuid&gt;
&lt;usage type='volume'&gt;
&lt;volume&gt;/var/lib/libvirt/images/luks-sample.img&lt;/volume&gt;
&lt;/usage&gt;
&lt;/secret&gt;
# virsh secret-define luks-secret.xml
Secret f52a81b2-424e-490c-823d-6bd4235bc57 created
#
# MYSECRET=`printf %s "letmein" | base64`
# virsh secret-set-value f52a81b2-424e-490c-823d-6bd4235bc57 $MYSECRET
Secret value set
#
</pre>
<p>
The volume type secret can be supplied in domain XML for a luks storage
volume <a href="formatstorageencryption.html">encryption</a> as follows:
</p>
<pre>
&lt;encryption format='luks'&gt;
&lt;secret type='passphrase' uuid='f52a81b2-424e-490c-823d-6bd4235bc57'/&gt;
&lt;/encryption&gt;
</pre>
<h3><a id="CephUsageType">Usage type "ceph"</a></h3>
<p>
This secret is associated with a Ceph RBD (rados block device).
The <code>&lt;usage type='ceph'&gt;</code> element must contain
a single <code>name</code> element that specifies a usage name
for the secret. The Ceph secret can then be used by UUID or by
this usage name via the <code>&lt;auth&gt;</code> element of
a <a href="formatdomain.html#elementsDisks">disk device</a> or
a <a href="formatstorage.html">storage pool (rbd)</a>.
<span class="since">Since 0.9.7</span>. The following is an example
of the steps to be taken. First create a ceph-secret.xml file:
</p>
<pre>
&lt;secret ephemeral='no' private='yes'&gt;
&lt;description&gt;CEPH passphrase example&lt;/description&gt;
&lt;usage type='ceph'&gt;
&lt;name&gt;ceph_example&lt;/name&gt;
&lt;/usage&gt;
&lt;/secret&gt;
</pre>
<p>
Next, use <code>virsh secret-define ceph-secret.xml</code> to define
the secret and <code>virsh secret-set-value</code> using the generated
UUID value and a base64 generated secret value in order to define the
chosen secret pass phrase.
</p>
<pre>
# virsh secret-define ceph-secret.xml
Secret 1b40a534-8301-45d5-b1aa-11894ebb1735 created
#
# virsh secret-list
UUID Usage
-----------------------------------------------------------
1b40a534-8301-45d5-b1aa-11894ebb1735 cephx ceph_example
#
# CEPHPHRASE=`printf %s "pass phrase" | base64`
# virsh secret-set-value 1b40a534-8301-45d5-b1aa-11894ebb1735 $CEPHPHRASE
Secret value set
#
</pre>
<p>
The ceph secret can then be used by UUID or by the
usage name via the <code>&lt;auth&gt;</code> element in a domain's
<a href="formatdomain.html#elementsDisks"><code>&lt;disk&gt;</code></a>
element as follows:
</p>
<pre>
&lt;auth username='myname'&gt;
&lt;secret type='ceph' usage='ceph_example'/&gt;
&lt;/auth&gt;
</pre>
<p>
As well as the <code>&lt;auth&gt;</code> element in a
<a href="formatstorage.html">storage pool (rbd)</a>
<code>&lt;source&gt;</code> element as follows:
</p>
<pre>
&lt;auth type='ceph' username='myname'&gt;
&lt;secret usage='ceph_example'/&gt;
&lt;/auth&gt;
</pre>
<h3><a id="iSCSIUsageType">Usage type "iscsi"</a></h3>
<p>
This secret is associated with an iSCSI target for CHAP authentication.
The <code>&lt;usage type='iscsi'&gt;</code> element must contain
a single <code>target</code> element that specifies a usage name
for the secret. The iSCSI secret can then be used by UUID or by
this usage name via the <code>&lt;auth&gt;</code> element of
a <a href="formatdomain.html#elementsDisks">disk device</a> or
a <a href="formatstorage.html">storage pool (iscsi)</a>.
<span class="since">Since 1.0.4</span>. The following is an example
of the XML that may be used to generate a secret for iSCSI CHAP
authentication. Assume the following sample entry in an iSCSI
authentication file:
</p>
<pre>
&lt;target iqn.2013-07.com.example:iscsi-pool&gt;
backing-store /home/tgtd/iscsi-pool/disk1
backing-store /home/tgtd/iscsi-pool/disk2
incominguser myname mysecret
&lt;/target&gt;
</pre>
<p>
Define an iscsi-secret.xml file to describe the secret. Use the
<code>incominguser</code> username used in your iSCSI authentication
configuration file as the value for the <code>username</code> attribute.
The <code>description</code> attribute should contain configuration
specific data. The <code>target</code> name may be any name of your
choosing to be used as the <code>usage</code> when used in the pool
or disk XML description.
</p>
<pre>
&lt;secret ephemeral='no' private='yes'&gt;
&lt;description&gt;Passphrase for the iSCSI example.com server&lt;/description&gt;
&lt;usage type='iscsi'&gt;
&lt;target&gt;libvirtiscsi&lt;/target&gt;
&lt;/usage&gt;
&lt;/secret&gt;
</pre>
<p>
Next, use <code>virsh secret-define iscsi-secret.xml</code> to define
the secret and <code>virsh secret-set-value</code> using the generated
UUID value and a base64 generated secret value in order to define the
chosen secret pass phrase. The pass phrase must match the password
used in the iSCSI authentication configuration file.
</p>
<pre>
# virsh secret-define secret.xml
Secret c4dbe20b-b1a3-4ac1-b6e6-2ac97852ebb6 created
# virsh secret-list
UUID Usage
-----------------------------------------------------------
c4dbe20b-b1a3-4ac1-b6e6-2ac97852ebb6 iscsi libvirtiscsi
# MYSECRET=`printf %s "mysecret" | base64`
# virsh secret-set-value c4dbe20b-b1a3-4ac1-b6e6-2ac97852ebb6 $MYSECRET
Secret value set
#
</pre>
<p>
The iSCSI secret can then be used by UUID or by the
usage name via the <code>&lt;auth&gt;</code> element in a domain's
<a href="formatdomain.html#elementsDisks"><code>&lt;disk&gt;</code></a>
element as follows:
</p>
<pre>
&lt;auth username='myname'&gt;
&lt;secret type='iscsi' usage='libvirtiscsi'/&gt;
&lt;/auth&gt;
</pre>
<p>
As well as the <code>&lt;auth&gt;</code> element in a
<a href="formatstorage.html">storage pool (iscsi)</a>
<code>&lt;source&gt;</code> element as follows:
</p>
<pre>
&lt;auth type='chap' username='myname'&gt;
&lt;secret usage='libvirtiscsi'/&gt;
&lt;/auth&gt;
</pre>
<h3><a id="tlsUsageType">Usage type "tls"</a></h3>
<p>
This secret may be used in order to provide the passphrase for the
private key used to provide TLS credentials.
The <code>&lt;usage type='tls'&gt;</code> element must contain a
single <code>name</code> element that specifies a usage name
for the secret.
<span class="since">Since 2.3.0</span>.
The following is an example of the expected XML and processing to
define the secret:
</p>
<pre>
# cat tls-secret.xml
&lt;secret ephemeral='no' private='yes'&gt;
&lt;description&gt;sample tls secret&lt;/description&gt;
&lt;usage type='tls'&gt;
&lt;name&gt;TLS_example&lt;/name&gt;
&lt;/usage&gt;
&lt;/secret&gt;
# virsh secret-define tls-secret.xml
Secret 718c71bd-67b5-4a2b-87ec-a24e8ca200dc created
# virsh secret-list
UUID Usage
-----------------------------------------------------------
718c71bd-67b5-4a2b-87ec-a24e8ca200dc tls TLS_example
#
</pre>
<p>
A secret may also be defined via the
<a href="html/libvirt-libvirt-secret.html#virSecretDefineXML">
<code>virSecretDefineXML</code></a> API.
Once the secret is defined, a secret value will need to be set. The
secret would be the passphrase used to access the TLS credentials.
The following is a simple example of using
<code>virsh secret-set-value</code> to set the secret value. The
<a href="html/libvirt-libvirt-secret.html#virSecretSetValue">
<code>virSecretSetValue</code></a> API may also be used to set
a more secure secret without using printable/readable characters.
</p>
<pre>
# MYSECRET=`printf %s "letmein" | base64`
# virsh secret-set-value 718c71bd-67b5-4a2b-87ec-a24e8ca200dc $MYSECRET
Secret value set
</pre>
</body>
</html>