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9dbf6871e6
Discourage passing secrets as commandline arguments. Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
415 lines
14 KiB
XML
415 lines
14 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<body>
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<h1>Secret XML format</h1>
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<ul id="toc"></ul>
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<h2><a id="SecretAttributes">Secret XML</a></h2>
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<p>
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Secrets stored by libvirt may have attributes associated with them, using
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the <code>secret</code> element. The <code>secret</code> element has two
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optional attributes, each with values '<code>yes</code>' and
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'<code>no</code>', and defaulting to '<code>no</code>':
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</p>
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<dl>
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<dt><code>ephemeral</code></dt>
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<dd>This secret must only be kept in memory, never stored persistently.
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</dd>
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<dt><code>private</code></dt>
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<dd>The value of the secret must not be revealed to any caller of libvirt,
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nor to any other node.
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</dd>
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</dl>
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<p>
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The top-level <code>secret</code> element may contain the following
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elements:
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</p>
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<dl>
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<dt><code>uuid</code></dt>
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<dd>
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An unique identifier for this secret (not necessarily in the UUID
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format). If omitted when defining a new secret, a random UUID is
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generated.
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</dd>
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<dt><code>description</code></dt>
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<dd>A human-readable description of the purpose of the secret.
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</dd>
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<dt><code>usage</code></dt>
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<dd>
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Specifies what this secret is used for. A mandatory
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<code>type</code> attribute specifies the usage category, currently
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only <code>volume</code>, <code>ceph</code>, <code>iscsi</code>,
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<code>tls</code>, and <code>vtpm</code> are defined. Specific usage
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categories are described below.
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</dd>
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</dl>
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<h3><a id="VolumeUsageType">Usage type "volume"</a></h3>
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<p>
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This secret is associated with a volume, whether the format is either
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for a "luks" encrypted volume. Each volume will have a
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unique secret associated with it and it is safe to delete the
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secret after the volume is deleted. The
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<code><usage type='volume'></code> element must contain a
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single <code>volume</code> element that specifies the path of the volume
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this secret is associated with. For example, create a volume-secret.xml
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file as follows:
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</p>
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<pre>
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<secret ephemeral='no' private='yes'>
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<description>Super secret name of my first puppy</description>
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<uuid>0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f</uuid>
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<usage type='volume'>
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<volume>/var/lib/libvirt/images/puppyname.img</volume>
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</usage>
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</secret>
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</pre>
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<p>
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Define the secret and set the passphrase as follows:
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</p>
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<pre>
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# virsh secret-define volume-secret.xml
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Secret 0a81f5b2-8403-7b23-c8d6-21ccc2f80d6f created
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</pre>
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<p>
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See <a href="#settingSecrets">virsh secret-set-value</a> on how
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to set the value of the secret.
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</p>
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<p>
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The volume type secret can be supplied either in volume XML during
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creation of a <a href="formatstorage.html#StorageVol">storage volume</a>
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in order to provide the passphrase to encrypt the volume or in
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domain XML <a href="formatdomain.html#elementsDisks">disk device</a>
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in order to provide the passphrase to decrypt the volume,
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<span class="since">since 2.1.0</span>. An example follows:
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</p>
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<pre>
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# cat luks-secret.xml
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<secret ephemeral='no' private='yes'>
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<description>LUKS Sample Secret</description>
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<uuid>f52a81b2-424e-490c-823d-6bd4235bc57</uuid>
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<usage type='volume'>
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<volume>/var/lib/libvirt/images/luks-sample.img</volume>
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</usage>
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</secret>
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# virsh secret-define luks-secret.xml
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Secret f52a81b2-424e-490c-823d-6bd4235bc57 created
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</pre>
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<p>
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See <a href="#settingSecrets">virsh secret-set-value</a> on how
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to set the value of the secret.
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</p>
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<p>
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The volume type secret can be supplied in domain XML for a luks storage
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volume <a href="formatstorageencryption.html">encryption</a> as follows:
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</p>
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<pre>
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<encryption format='luks'>
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<secret type='passphrase' uuid='f52a81b2-424e-490c-823d-6bd4235bc57'/>
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</encryption>
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</pre>
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<h3><a id="CephUsageType">Usage type "ceph"</a></h3>
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<p>
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This secret is associated with a Ceph RBD (rados block device).
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The <code><usage type='ceph'></code> element must contain
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a single <code>name</code> element that specifies a usage name
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for the secret. The Ceph secret can then be used by UUID or by
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this usage name via the <code><auth></code> element of
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a <a href="formatdomain.html#elementsDisks">disk device</a> or
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a <a href="formatstorage.html">storage pool (rbd)</a>.
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<span class="since">Since 0.9.7</span>. The following is an example
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of the steps to be taken. First create a ceph-secret.xml file:
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</p>
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<pre>
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<secret ephemeral='no' private='yes'>
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<description>CEPH passphrase example</description>
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<usage type='ceph'>
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<name>ceph_example</name>
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</usage>
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</secret>
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</pre>
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<p>
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Next, use <code>virsh secret-define ceph-secret.xml</code> to define
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the secret and <code>virsh secret-set-value</code> using the generated
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UUID value and a base64 generated secret value in order to define the
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chosen secret pass phrase.
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</p>
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<pre>
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# virsh secret-define ceph-secret.xml
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Secret 1b40a534-8301-45d5-b1aa-11894ebb1735 created
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#
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# virsh secret-list
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UUID Usage
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-----------------------------------------------------------
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1b40a534-8301-45d5-b1aa-11894ebb1735 cephx ceph_example
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</pre>
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<p>
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See <a href="#settingSecrets">virsh secret-set-value</a> on how
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to set the value of the secret.
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</p>
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<p>
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The ceph secret can then be used by UUID or by the
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usage name via the <code><auth></code> element in a domain's
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<a href="formatdomain.html#elementsDisks"><code><disk></code></a>
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element as follows:
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</p>
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<pre>
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<auth username='myname'>
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<secret type='ceph' usage='ceph_example'/>
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</auth>
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</pre>
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<p>
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As well as the <code><auth></code> element in a
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<a href="formatstorage.html">storage pool (rbd)</a>
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<code><source></code> element as follows:
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</p>
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<pre>
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<auth type='ceph' username='myname'>
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<secret usage='ceph_example'/>
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</auth>
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</pre>
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<h3><a id="iSCSIUsageType">Usage type "iscsi"</a></h3>
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<p>
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This secret is associated with an iSCSI target for CHAP authentication.
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The <code><usage type='iscsi'></code> element must contain
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a single <code>target</code> element that specifies a usage name
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for the secret. The iSCSI secret can then be used by UUID or by
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this usage name via the <code><auth></code> element of
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a <a href="formatdomain.html#elementsDisks">disk device</a> or
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a <a href="formatstorage.html">storage pool (iscsi)</a>.
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<span class="since">Since 1.0.4</span>. The following is an example
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of the XML that may be used to generate a secret for iSCSI CHAP
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authentication. Assume the following sample entry in an iSCSI
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authentication file:
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</p>
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<pre>
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<target iqn.2013-07.com.example:iscsi-pool>
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backing-store /home/tgtd/iscsi-pool/disk1
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backing-store /home/tgtd/iscsi-pool/disk2
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incominguser myname mysecret
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</target>
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</pre>
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<p>
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Define an iscsi-secret.xml file to describe the secret. Use the
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<code>incominguser</code> username used in your iSCSI authentication
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configuration file as the value for the <code>username</code> attribute.
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The <code>description</code> attribute should contain configuration
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specific data. The <code>target</code> name may be any name of your
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choosing to be used as the <code>usage</code> when used in the pool
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or disk XML description.
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</p>
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<pre>
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<secret ephemeral='no' private='yes'>
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<description>Passphrase for the iSCSI example.com server</description>
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<usage type='iscsi'>
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<target>libvirtiscsi</target>
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</usage>
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</secret>
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</pre>
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<p>
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Next, use <code>virsh secret-define iscsi-secret.xml</code> to define
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the secret and
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<code><a href="#settingSecrets">virsh secret-set-value</a></code>
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using the generated
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UUID value and a base64 generated secret value in order to define the
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chosen secret pass phrase. The pass phrase must match the password
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used in the iSCSI authentication configuration file.
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</p>
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<pre>
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# virsh secret-define secret.xml
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Secret c4dbe20b-b1a3-4ac1-b6e6-2ac97852ebb6 created
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# virsh secret-list
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UUID Usage
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-----------------------------------------------------------
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c4dbe20b-b1a3-4ac1-b6e6-2ac97852ebb6 iscsi libvirtiscsi
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</pre>
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<p>
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See <a href="#settingSecrets">virsh secret-set-value</a> on how
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to set the value of the secret.
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</p>
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<p>
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The iSCSI secret can then be used by UUID or by the
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usage name via the <code><auth></code> element in a domain's
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<a href="formatdomain.html#elementsDisks"><code><disk></code></a>
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element as follows:
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</p>
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<pre>
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<auth username='myname'>
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<secret type='iscsi' usage='libvirtiscsi'/>
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</auth>
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</pre>
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<p>
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As well as the <code><auth></code> element in a
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<a href="formatstorage.html">storage pool (iscsi)</a>
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<code><source></code> element as follows:
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</p>
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<pre>
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<auth type='chap' username='myname'>
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<secret usage='libvirtiscsi'/>
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</auth>
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</pre>
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<h3><a id="tlsUsageType">Usage type "tls"</a></h3>
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<p>
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This secret may be used in order to provide the passphrase for the
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private key used to provide TLS credentials.
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The <code><usage type='tls'></code> element must contain a
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single <code>name</code> element that specifies a usage name
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for the secret.
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<span class="since">Since 2.3.0</span>.
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The following is an example of the expected XML and processing to
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define the secret:
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</p>
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<pre>
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# cat tls-secret.xml
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<secret ephemeral='no' private='yes'>
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<description>sample tls secret</description>
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<usage type='tls'>
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<name>TLS_example</name>
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</usage>
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</secret>
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# virsh secret-define tls-secret.xml
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Secret 718c71bd-67b5-4a2b-87ec-a24e8ca200dc created
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# virsh secret-list
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UUID Usage
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-----------------------------------------------------------
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718c71bd-67b5-4a2b-87ec-a24e8ca200dc tls TLS_example
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#
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</pre>
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<p>
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A secret may also be defined via the
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<a href="html/libvirt-libvirt-secret.html#virSecretDefineXML">
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<code>virSecretDefineXML</code></a> API.
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Once the secret is defined, a secret value will need to be set. The
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secret would be the passphrase used to access the TLS credentials.
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The following is a simple example of using
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<code><a href="#settingSecrets">virsh secret-set-value</a></code> to set
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the secret value. The
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<a href="html/libvirt-libvirt-secret.html#virSecretSetValue">
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<code>virSecretSetValue</code></a> API may also be used to set
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a more secure secret without using printable/readable characters.
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</p>
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<h3><a id="vTPMUsageType">Usage type "vtpm"</a></h3>
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<p>
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This secret is associated with a virtualized TPM (vTPM) and serves
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as a passphrase for deriving a key from for encrypting the state
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of the vTPM.
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The <code><usage type='vtpm'></code> element must contain
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a single <code>name</code> element that specifies a usage name
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for the secret. The vTPM secret can then be used by UUID
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via the <code><encryption></code> element of
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a <a href="formatdomain.html#elementsTpm">tpm</a> when using an
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emulator.
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<span class="since">Since 5.6.0</span>. The following is an example
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of the steps to be taken. First create a vtpm-secret.xml file: </p>
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<pre>
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# cat vtpm-secret.xml
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<secret ephemeral='no' private='yes'>
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<description>sample vTPM secret</description>
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<usage type='vtpm'>
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<name>VTPM_example</name>
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</usage>
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</secret>
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# virsh secret-define vtpm-secret.xml
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Secret 6dd3e4a5-1d76-44ce-961f-f119f5aad935 created
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# virsh secret-list
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UUID Usage
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----------------------------------------------------------------------------------------
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6dd3e4a5-1d76-44ce-961f-f119f5aad935 vtpm VTPM_example
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#
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</pre>
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<p>
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A secret may also be defined via the
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<a href="html/libvirt-libvirt-secret.html#virSecretDefineXML">
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<code>virSecretDefineXML</code></a> API.
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Once the secret is defined, a secret value will need to be set. The
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secret would be the passphrase used to decrypt the vTPM state.
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The following is a simple example of using
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<code><a href="#settingSecrets">virsh secret-set-value</a></code>
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to set the secret value. The
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<a href="html/libvirt-libvirt-secret.html#virSecretSetValue">
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<code>virSecretSetValue</code></a> API may also be used to set
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a more secure secret without using printable/readable characters.
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</p>
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<h2><a id="settingSecrets">Setting secret values in virsh</a></h2>
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<p>
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To set the value of the secret you can use the following virsh commands.
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If the secret is a password-like string (printable characters, no newline)
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you can use:
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</p>
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<pre>
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# virsh secret-set-value --interactive 6dd3e4a5-1d76-44ce-961f-f119f5aad935
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Enter new value for secret:
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Secret value set
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</pre>
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<p>
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Another secure option is to read the secret from a file. This way the
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secret can contain any bytes (even NUL and non-printable characters). The
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length of the secret is the length of the input file. Alternatively the
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<code>--plain</code> option can be omitted if the file contents are
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base64-encoded.
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</p>
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<pre>
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# virsh secret-set-value 6dd3e4a5-1d76-44ce-961f-f119f5aad935 --file --plain secretinfile
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Secret value set
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</pre>
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<p>
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<b>WARNING</b> The following approach is <b>insecure</b> and deprecated.
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The secret can also be set via an argument. Note that other users may see
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the actual secret in the process listing!
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The secret must be base64 encoded.
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</p>
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<pre>
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# MYSECRET=`printf %s "open sesame" | base64`
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# virsh secret-set-value 6dd3e4a5-1d76-44ce-961f-f119f5aad935 $MYSECRET
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Secret value set
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</pre>
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</body>
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</html>
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