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<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>,
<code>tls</code>, and <code>vtpm</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><usage type='volume'></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>
<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>
</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
</pre>
<p>
See <a href="#settingSecrets">virsh secret-set-value</a> on how
to set the value of the secret.
</p>
<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
<secret ephemeral='no' private='yes'>
<description>LUKS Sample Secret</description>
<uuid>f52a81b2-424e-490c-823d-6bd4235bc57</uuid>
<usage type='volume'>
<volume>/var/lib/libvirt/images/luks-sample.img</volume>
</usage>
</secret>
# virsh secret-define luks-secret.xml
Secret f52a81b2-424e-490c-823d-6bd4235bc57 created
</pre>
<p>
See <a href="#settingSecrets">virsh secret-set-value</a> on how
to set the value of the secret.
</p>
<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>
<encryption format='luks'>
<secret type='passphrase' uuid='f52a81b2-424e-490c-823d-6bd4235bc57'/>
</encryption>
</pre>
<h3><a id="CephUsageType">Usage type "ceph"</a></h3>
<p>
This secret is associated with a Ceph RBD (rados block device).
The <code><usage type='ceph'></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><auth></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>
<secret ephemeral='no' private='yes'>
<description>CEPH passphrase example</description>
<usage type='ceph'>
<name>ceph_example</name>
</usage>
</secret>
</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
</pre>
<p>
See <a href="#settingSecrets">virsh secret-set-value</a> on how
to set the value of the secret.
</p>
<p>
The ceph secret can then be used by UUID or by the
usage name via the <code><auth></code> element in a domain's
<a href="formatdomain.html#elementsDisks"><code><disk></code></a>
element as follows:
</p>
<pre>
<auth username='myname'>
<secret type='ceph' usage='ceph_example'/>
</auth>
</pre>
<p>
As well as the <code><auth></code> element in a
<a href="formatstorage.html">storage pool (rbd)</a>
<code><source></code> element as follows:
</p>
<pre>
<auth type='ceph' username='myname'>
<secret usage='ceph_example'/>
</auth>
</pre>
<h3><a id="iSCSIUsageType">Usage type "iscsi"</a></h3>
<p>
This secret is associated with an iSCSI target for CHAP authentication.
The <code><usage type='iscsi'></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><auth></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>
<target iqn.2013-07.com.example:iscsi-pool>
backing-store /home/tgtd/iscsi-pool/disk1
backing-store /home/tgtd/iscsi-pool/disk2
incominguser myname mysecret
</target>
</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>
<secret ephemeral='no' private='yes'>
<description>Passphrase for the iSCSI example.com server</description>
<usage type='iscsi'>
<target>libvirtiscsi</target>
</usage>
</secret>
</pre>
<p>
Next, use <code>virsh secret-define iscsi-secret.xml</code> to define
the secret and
<code><a href="#settingSecrets">virsh secret-set-value</a></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
</pre>
<p>
See <a href="#settingSecrets">virsh secret-set-value</a> on how
to set the value of the secret.
</p>
<p>
The iSCSI secret can then be used by UUID or by the
usage name via the <code><auth></code> element in a domain's
<a href="formatdomain.html#elementsDisks"><code><disk></code></a>
element as follows:
</p>
<pre>
<auth username='myname'>
<secret type='iscsi' usage='libvirtiscsi'/>
</auth>
</pre>
<p>
As well as the <code><auth></code> element in a
<a href="formatstorage.html">storage pool (iscsi)</a>
<code><source></code> element as follows:
</p>
<pre>
<auth type='chap' username='myname'>
<secret usage='libvirtiscsi'/>
</auth>
</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><usage type='tls'></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
<secret ephemeral='no' private='yes'>
<description>sample tls secret</description>
<usage type='tls'>
<name>TLS_example</name>
</usage>
</secret>
# 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><a href="#settingSecrets">virsh secret-set-value</a></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>
<h3><a id="vTPMUsageType">Usage type "vtpm"</a></h3>
<p>
This secret is associated with a virtualized TPM (vTPM) and serves
as a passphrase for deriving a key from for encrypting the state
of the vTPM.
The <code><usage type='vtpm'></code> element must contain
a single <code>name</code> element that specifies a usage name
for the secret. The vTPM secret can then be used by UUID
via the <code><encryption></code> element of
a <a href="formatdomain.html#elementsTpm">tpm</a> when using an
emulator.
<span class="since">Since 5.6.0</span>. The following is an example
of the steps to be taken. First create a vtpm-secret.xml file: </p>
<pre>
# cat vtpm-secret.xml
<secret ephemeral='no' private='yes'>
<description>sample vTPM secret</description>
<usage type='vtpm'>
<name>VTPM_example</name>
</usage>
</secret>
# virsh secret-define vtpm-secret.xml
Secret 6dd3e4a5-1d76-44ce-961f-f119f5aad935 created
# virsh secret-list
UUID Usage
----------------------------------------------------------------------------------------
6dd3e4a5-1d76-44ce-961f-f119f5aad935 vtpm VTPM_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 decrypt the vTPM state.
The following is a simple example of using
<code><a href="#settingSecrets">virsh secret-set-value</a></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>
<h2><a id="settingSecrets">Setting secret values in virsh</a></h2>
<p>
To set the value of the secret you can use the following virsh commands.
If the secret is a password-like string (printable characters, no newline)
you can use:
</p>
<pre>
# virsh secret-set-value --interactive 6dd3e4a5-1d76-44ce-961f-f119f5aad935
Enter new value for secret:
Secret value set
</pre>
<p>
Another secure option is to read the secret from a file. This way the
secret can contain any bytes (even NUL and non-printable characters). The
length of the secret is the length of the input file. Alternatively the
<code>--plain</code> option can be omitted if the file contents are
base64-encoded.
</p>
<pre>
# virsh secret-set-value 6dd3e4a5-1d76-44ce-961f-f119f5aad935 --file --plain secretinfile
Secret value set
</pre>
<p>
<b>WARNING</b> The following approach is <b>insecure</b> and deprecated.
The secret can also be set via an argument. Note that other users may see
the actual secret in the process listing!
The secret must be base64 encoded.
</p>
<pre>
# MYSECRET=`printf %s "open sesame" | base64`
# virsh secret-set-value 6dd3e4a5-1d76-44ce-961f-f119f5aad935 $MYSECRET
Secret value set
</pre>
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