mirror of
https://gitlab.com/libvirt/libvirt.git
synced 2024-12-22 17:34:18 +03:00
df99aa311a
The generation and deployment of x509 certificates for TLS is complex and verbose and thus deserves its own standalone page. Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
414 lines
13 KiB
XML
414 lines
13 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html>
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|
<body>
|
|
<h1>TLS x509 certificate setup</h1>
|
|
|
|
<ul id="toc"></ul>
|
|
|
|
<h2>
|
|
<a id="Remote_PKI">Public Key Infrastructure set up</a>
|
|
</h2>
|
|
<p>
|
|
If you are unsure how to create TLS certificates, skip to the
|
|
next section.
|
|
</p>
|
|
<table class="top_table">
|
|
<tr>
|
|
<th> Location </th>
|
|
<th> Machine </th>
|
|
<th> Description </th>
|
|
<th> Required fields </th>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>/etc/pki/CA/cacert.pem</code>
|
|
</td>
|
|
<td> Installed on the client and server </td>
|
|
<td> CA's certificate (<a href="#Remote_TLS_CA">more info</a>)</td>
|
|
<td> n/a </td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>$HOME/.pki/cacert.pem</code>
|
|
</td>
|
|
<td> Installed on the client </td>
|
|
<td> CA's certificate (<a href="#Remote_TLS_CA">more info</a>)</td>
|
|
<td> n/a </td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>/etc/pki/libvirt/private/serverkey.pem</code>
|
|
</td>
|
|
<td> Installed on the server </td>
|
|
<td> Server's private key (<a href="#Remote_TLS_server_certificates">more info</a>)</td>
|
|
<td> n/a </td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>/etc/pki/libvirt/servercert.pem</code>
|
|
</td>
|
|
<td> Installed on the server </td>
|
|
<td> Server's certificate signed by the CA.
|
|
(<a href="#Remote_TLS_server_certificates">more info</a>) </td>
|
|
<td> CommonName (CN) must be the hostname of the server as it
|
|
is seen by clients. All hostname and IP address variants that might
|
|
be used to reach the server should be listed in Subject Alt Name
|
|
fields.</td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>/etc/pki/libvirt/private/clientkey.pem</code>
|
|
</td>
|
|
<td> Installed on the client </td>
|
|
<td> Client's private key. (<a href="#Remote_TLS_client_certificates">more info</a>) </td>
|
|
<td> n/a </td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>/etc/pki/libvirt/clientcert.pem</code>
|
|
</td>
|
|
<td> Installed on the client </td>
|
|
<td> Client's certificate signed by the CA
|
|
(<a href="#Remote_TLS_client_certificates">more info</a>) </td>
|
|
<td> Distinguished Name (DN) can be checked against an access
|
|
control list (<code>tls_allowed_dn_list</code>).
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>$HOME/.pki/libvirt/clientkey.pem</code>
|
|
</td>
|
|
<td> Installed on the client </td>
|
|
<td> Client's private key. (<a href="#Remote_TLS_client_certificates">more info</a>) </td>
|
|
<td> n/a </td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<code>$HOME/.pki/libvirt/clientcert.pem</code>
|
|
</td>
|
|
<td> Installed on the client </td>
|
|
<td> Client's certificate signed by the CA
|
|
(<a href="#Remote_TLS_client_certificates">more info</a>) </td>
|
|
<td> Distinguished Name (DN) can be checked against an access
|
|
control list (<code>tls_allowed_dn_list</code>).
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<p>
|
|
If 'pkipath' is specified in URI, then all the client
|
|
certificates must be found in the path specified, otherwise the
|
|
connection will fail with a fatal error. If 'pkipath' is not
|
|
specified:
|
|
</p>
|
|
<ul>
|
|
<li> For a non-root user, libvirt tries to find the certificates
|
|
in $HOME/.pki/libvirt first. If the required CA certificate cannot
|
|
be found, then the global default location
|
|
(/etc/pki/CA/cacert.pem) will be used.
|
|
Likewise, if either the client certificate
|
|
or the client key cannot be found, then the global default
|
|
locations (/etc/pki/libvirt/clientcert.pem,
|
|
/etc/pki/libvirt/private/clientkey.pem) will be used.
|
|
</li>
|
|
<li> For the root user, the global default locations will always be used.</li>
|
|
</ul>
|
|
<h2>
|
|
<a id="Remote_TLS_background">Background to TLS certificates</a>
|
|
</h2>
|
|
<p>
|
|
Libvirt supports TLS certificates for verifying the identity
|
|
of the server and clients. There are two distinct checks involved:
|
|
</p>
|
|
<ul>
|
|
<li> The client should know that it is connecting to the right
|
|
server. Checking done by client by matching the certificate that
|
|
the server sends to the server's hostname. May be disabled by adding
|
|
<code>?no_verify=1</code> to the
|
|
<a href="#Remote_URI_parameters">remote URI</a>.
|
|
</li>
|
|
<li> The server should know that only permitted clients are
|
|
connecting. This can be done based on client's IP address, or on
|
|
client's IP address and client's certificate. Checking done by the
|
|
server. May be enabled and disabled in the <a href="#Remote_libvirtd_configuration">libvirtd.conf file</a>.
|
|
</li>
|
|
</ul>
|
|
<p>
|
|
For full certificate checking you will need to have certificates
|
|
issued by a recognised <a href="http://en.wikipedia.org/wiki/Certificate_authority">Certificate
|
|
Authority (CA)</a> for your server(s) and all clients. To avoid the
|
|
expense of getting certificates from a commercial CA, you can set up
|
|
your own CA and tell your server(s) and clients to trust certificates
|
|
issues by your own CA. Follow the instructions in the next section.
|
|
</p>
|
|
<p>
|
|
Be aware that the <a href="#Remote_libvirtd_configuration">default
|
|
configuration for libvirtd</a> allows any client to connect provided
|
|
they have a valid certificate issued by the CA for their own IP
|
|
address. You may want to change this to make it less (or more)
|
|
permissive, depending on your needs.
|
|
</p>
|
|
<h2>
|
|
<a id="Remote_TLS_CA">Setting up a Certificate Authority (CA)</a>
|
|
</h2>
|
|
<p>
|
|
You will need the <a href="http://www.gnu.org/software/gnutls/manual/html_node/Invoking-certtool.html">GnuTLS
|
|
certtool program documented here</a>. In Fedora, it is in the
|
|
<code>gnutls-utils</code> package.
|
|
</p>
|
|
<p>
|
|
Create a private key for your CA:
|
|
</p>
|
|
<pre>
|
|
certtool --generate-privkey > cakey.pem
|
|
</pre>
|
|
<p>
|
|
and self-sign it by creating a file with the
|
|
signature details called
|
|
<code>ca.info</code> containing:
|
|
</p>
|
|
<pre>
|
|
cn = <i>Name of your organization</i>
|
|
ca
|
|
cert_signing_key
|
|
</pre>
|
|
<pre>
|
|
certtool --generate-self-signed --load-privkey cakey.pem \
|
|
--template ca.info --outfile cacert.pem
|
|
</pre>
|
|
<p>
|
|
(You can delete <code>ca.info</code> file now if you
|
|
want).
|
|
</p>
|
|
<p>
|
|
Now you have two files which matter:
|
|
</p>
|
|
<ul>
|
|
<li><code>cakey.pem</code> - Your CA's private key (keep this very secret!)
|
|
</li>
|
|
<li><code>cacert.pem</code> - Your CA's certificate (this is public).
|
|
</li>
|
|
</ul>
|
|
<p><code>cacert.pem</code> has to be installed on clients and
|
|
server(s) to let them know that they can trust certificates issued by
|
|
your CA.
|
|
</p>
|
|
<p>
|
|
The normal installation directory for <code>cacert.pem</code>
|
|
is <code>/etc/pki/CA/cacert.pem</code> on all clients and servers.
|
|
</p>
|
|
<p>
|
|
To see the contents of this file, do:
|
|
</p>
|
|
<pre><b>certtool -i --infile cacert.pem</b>
|
|
|
|
X.509 certificate info:
|
|
|
|
Version: 3
|
|
Serial Number (hex): 00
|
|
Subject: CN=Libvirt Project
|
|
Issuer: CN=Libvirt Project
|
|
Signature Algorithm: RSA-SHA
|
|
Validity:
|
|
Not Before: Mon Jun 18 16:22:18 2007
|
|
Not After: Tue Jun 17 16:22:18 2008
|
|
<i>[etc]</i>
|
|
</pre>
|
|
<p>
|
|
This is all that is required to set up your CA. Keep the CA's private
|
|
key carefully as you will need it when you come to issue certificates
|
|
for your clients and servers.
|
|
</p>
|
|
<h2>
|
|
<a id="Remote_TLS_server_certificates">Issuing server certificates</a>
|
|
</h2>
|
|
<p>
|
|
For each server (libvirtd) you need to issue a certificate
|
|
containing one or more hostnames and/or IP addresses.
|
|
Historically the CommonName (CN) field would contain the
|
|
hostname of the server and would match the hostname used
|
|
in the URI that clients pass to libvirt. In most TLS implementations
|
|
the CN field is considered legacy data. The preferential mechanism
|
|
is to use Subject Alt Name (SAN) extension fields to validate
|
|
against. In the future use of the CN field for validation may be
|
|
discontinued entirely, so it is strongly recommended to
|
|
include the SAN fields.
|
|
</p>
|
|
<p>
|
|
In the example below, clients will be connecting to the
|
|
server using a <a href="#Remote_URI_reference">URI</a> of
|
|
<code>qemu://compute1.libvirt.org/system</code>, so the CN
|
|
must be "<code>compute1.libvirt.org</code>".
|
|
</p>
|
|
<p>
|
|
Make a private key for the server:
|
|
</p>
|
|
<pre>
|
|
certtool --generate-privkey > serverkey.pem
|
|
</pre>
|
|
<p>
|
|
and sign that key with the CA's private key by first
|
|
creating a template file called <code>server.info</code>.
|
|
The template file will contain a number of fields to define
|
|
the server as follows:
|
|
</p>
|
|
<pre>
|
|
organization = <i>Name of your organization</i>
|
|
cn = compute1.libvirt.org
|
|
dns_name = compute1
|
|
dns_name = compute1.libvirt.org
|
|
ip_address = 10.0.0.74
|
|
ip_address = 192.168.1.24
|
|
ip_address = 2001:cafe::74
|
|
ip_address = fe20::24
|
|
tls_www_server
|
|
encryption_key
|
|
signing_key
|
|
</pre>
|
|
<p>
|
|
The 'cn' field should refer to the fully qualified public
|
|
hostname of the server. For the SAN extension data, there
|
|
must also be one or more 'dns_name' fields that contain all
|
|
possible hostnames that can be reasonably used by clients
|
|
to reach the server, both with and without domain name
|
|
qualifiers. If clients are likely to connect to the server
|
|
by IP address, then one or more 'ip_address' fields should
|
|
also be added.
|
|
</p>
|
|
<p>
|
|
Use the template file as input to a <code>certtool</code>
|
|
command to sign the server certificate:
|
|
</p>
|
|
<pre>
|
|
certtool --generate-certificate --load-privkey serverkey.pem \
|
|
--load-ca-certificate cacert.pem --load-ca-privkey cakey.pem \
|
|
--template server.info --outfile servercert.pem
|
|
</pre>
|
|
<p>
|
|
This gives two files:
|
|
</p>
|
|
<ul>
|
|
<li><code>serverkey.pem</code> - The server's private key.
|
|
</li>
|
|
<li><code>servercert.pem</code> - The server's public key.
|
|
</li>
|
|
</ul>
|
|
<p>
|
|
We can examine this certificate and its signature:
|
|
</p>
|
|
<pre><b>certtool -i --infile servercert.pem</b>
|
|
X.509 certificate info:
|
|
|
|
Version: 3
|
|
Serial Number (hex): 00
|
|
Subject: O=Libvirt Project,CN=compute1.libvirt.org
|
|
Issuer: CN=Libvirt Project
|
|
Signature Algorithm: RSA-SHA
|
|
Validity:
|
|
Not Before: Wed Oct 04 09:09:44 UTC 2017
|
|
Not After: Thu Oct 04 09:09:44 UTC 2018
|
|
Extensions:
|
|
Basic Constraints (critical):
|
|
Certificate Authority (CA): FALSE
|
|
Subject Alternative Name (not critical):
|
|
DNSname: compute1
|
|
DNSname: compute1.libvirt.org
|
|
IPAddress: 10.0.0.74
|
|
IPAddress: 192.168.1.24
|
|
IPAddress: 2001:cafe::74
|
|
IPAddress: fe20::24
|
|
</pre>
|
|
<p>
|
|
Note the "Issuer" CN is "Libvirt Project" (the CA) and
|
|
the "Subject" CN is "compute1.libvirt.org" (the server).
|
|
Notice that the hostname listed in the CN must also
|
|
be duplicated as a DNSname entry
|
|
</p>
|
|
<p>
|
|
Finally we have two files to install:
|
|
</p>
|
|
<ul>
|
|
<li><code>serverkey.pem</code> is
|
|
the server's private key which should be copied to the
|
|
server <i>only</i> as
|
|
<code>/etc/pki/libvirt/private/serverkey.pem</code>.
|
|
</li>
|
|
<li><code>servercert.pem</code> is the server's certificate
|
|
which can be installed on the server as
|
|
<code>/etc/pki/libvirt/servercert.pem</code>.
|
|
</li>
|
|
</ul>
|
|
<h2>
|
|
<a id="Remote_TLS_client_certificates">Issuing client certificates</a>
|
|
</h2>
|
|
<p>
|
|
For each client (ie. any program linked with libvirt, such as
|
|
<a href="http://virt-manager.org/">virt-manager</a>)
|
|
you need to issue a certificate with the X.509 Distinguished Name (DN)
|
|
set to a suitable name. You can decide this on a company / organisation
|
|
policy. For example:
|
|
</p>
|
|
<pre>
|
|
C=GB,ST=London,L=London,O=Libvirt Project,CN=<i>name_of_client</i>
|
|
</pre>
|
|
<p>
|
|
The process is the same as for
|
|
<a href="#Remote_TLS_server_certificates">setting up the
|
|
server certificate</a> so here we just briefly cover the
|
|
steps.
|
|
</p>
|
|
<ol>
|
|
<li>
|
|
Make a private key:
|
|
<pre>
|
|
certtool --generate-privkey > clientkey.pem
|
|
</pre>
|
|
</li>
|
|
<li>
|
|
Act as CA and sign the certificate. Create client.info containing:
|
|
<pre>
|
|
country = GB
|
|
state = London
|
|
locality = London
|
|
organization = Libvirt Project
|
|
cn = client1
|
|
tls_www_client
|
|
encryption_key
|
|
signing_key
|
|
</pre>
|
|
and sign by doing:
|
|
<pre>
|
|
certtool --generate-certificate --load-privkey clientkey.pem \
|
|
--load-ca-certificate cacert.pem --load-ca-privkey cakey.pem \
|
|
--template client.info --outfile clientcert.pem
|
|
</pre>
|
|
</li>
|
|
<li>
|
|
Install the certificates on the client machine:
|
|
<pre>
|
|
cp clientkey.pem /etc/pki/libvirt/private/clientkey.pem
|
|
cp clientcert.pem /etc/pki/libvirt/clientcert.pem
|
|
</pre>
|
|
</li>
|
|
</ol>
|
|
<h2>
|
|
<a id="Remote_TLS_troubleshooting">Troubleshooting TLS certificate problems</a>
|
|
</h2>
|
|
<dl>
|
|
<dt> failed to verify client's certificate </dt>
|
|
<dd>
|
|
<p>
|
|
On the server side, run the libvirtd server with
|
|
the '--listen' and '--verbose' options while the
|
|
client is connecting. The verbose log messages should
|
|
tell you enough to diagnose the problem.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
<p> You can use the virt-pki-validate shell script
|
|
to analyze the setup on the client or server machines, preferably as root.
|
|
It will try to point out the possible problems and provide solutions to
|
|
fix the set up up to a point where you have secure remote access.</p>
|
|
</body>
|
|
</html>
|