Using the X509 authentication source with simpleSAMLphp

The authX509 module provide X509 authentication with certificate validation. For now there is only one authentication source:

authX509userCert Validate against LDAP userCertificate attribute

More validation schemes (OCSP, CRL, local list) might be added later.

1 Configuring Apache

This module assumes that the server requests a client certificate, and stores it in the environment variable SSL_CLIENT_CERT. This can be achieved with such a configuration:

SSLEngine on
SSLCertificateFile /etc/openssl/certs/server.crt
SSLCertificateKeyFile /etc/openssl/private/server.key
SSLCACertificateFile /etc/openssl/certs/ca.crt
SSLVerifyClient require
SSLVerifyDepth 2
SSLOptions +ExportCertData

Note that SSLVerifyClient can be set to optional if you want to support both certificate and plain login authentication at the same time (more on this later).

If your server or your client (or both!) have TLS renegociation disabled as a workaround for CVE-2009-3555, then the configuration directive above must not appear in a , , or in a name-based . You can only use them server-wide, or in with different IP address/port combinaisons.

2 Setting up the authX509 module

The first thing you need to do is to enable the cas module:

touch modules/authX509/enable

Then you must add it as an authentication source. Here is an example authsource.php

'x509' => array(
    'authX509:X509userCert',
    'hostname' => 'ldaps://ldap.example.net',
    'enable_tls' => FALSE,
    'attributes' => array("cn", "uid", "mail", "ou", "sn"),
    'search.enable' => TRUE,
    'search.attributes' => array('uid', 'mail'),
    'search.base' => 'dc=example,dc=net',
    'x509attributes' => array('UID' => 'uid'),
    'ldapusercert' => array('userCertificate;binary'),
),

The configuration is the same as for the LDAP module, except for two options:

x509attributes is used to map a certificate subject attribute to an LDAP attribute. It is used to find the certificate owner in LDAP from the certificate subject. If multiple mappings are provided, any mappping will match (this is a logical OR). Default is array('UID' => 'uid')
ldapusercert the LDAP attribute in which the user certificate will be found. Default is userCertificate;binary

3 Uploading certificate in LDAP

Certificate are usually stored in LDAP as DER, in binary. Here is how to convert from PEM to DER:

openssl x509 -in cert.pem -inform PEM -outform DER -out cert.der

Here is some LDIF to upload the certificate in the directory:

dn: uid=jdoe,dc=example,dc=net
changetype: modify
add: userCertificate;binary
userCertificate;binary:< file:///path/to/cert.der

Supporting both certificate and login authentications

In your Apache configuration, set SSLVerifyClient to optional. Then you can hack your metadata/saml20-idp-hosted.php file that way:

$auth_source = empty($_SERVER['SSL_CLIENT_CERT']) ? 'ldap' : 'x509';
$metadata = array(
    '__DYNAMIC:1__' => array(
        'host'          =>      '__DEFAULT__',
        'privatekey'    =>      'server.key',
        'certificate'   =>      'server.crt',
        'auth'          =>       $auth_source,
        'authority'     =>      'login',
        'userid.attribute' =>   'uid',
        'logouttype'    =>      'iframe',
        'AttributeNameFormat' =>
                        'urn:oasis:names:tc:SAML:2.0:attrname-format:uri',
)

Warning

Using the X509 authentication source with simpleSAMLphp

1 Configuring Apache

2 Setting up the authX509 module

3 Uploading certificate in LDAP

Supporting both certificate and login authentications