authX509: Make ldapusercert validation optional.

This patch makes it possible to skip validating the certificate
against an attribute in the LDAP directory, and instead trust that
Apache has checked it.

In addtition it contains some bugfixes and documentation fixes.

Thanks to Thijs Kinkhorst for this patch!

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@3234 44740490-163a-0410-bde0-09ae8108e29a

modules/authX509/docs/authX509.txt

 Using the X509 authentication source with simpleSAMLphp
 =======================================================
 
-The authX509 module provide X509 authentication with certificate
+The authX509 module provides X509 authentication with certificate
 validation. For now there is only one authentication source:
 
 * authX509userCert Validate against LDAP userCertificate attribute
@@ -27,22 +27,22 @@ 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
+If your server or your client (or both!) have TLS renegotiation disabled
 as a workaround for CVE-2009-3555, then the configuration directive above
 must not appear in a <Directory>, <Location>, or in a name-based
-<VirtualHost>. You can only use them server-wide, or in <VirtualHost>
-with different IP address/port combinaisons.
+<VirtualHost>. You can only use them server-wide, or in <VirtualHost>s
+with different IP address/port combinations.
 
 
 Setting up the authX509 module
 ------------------------------
 
-The first thing you need to do is to enable the cas module:
+The first thing you need to do is to enable the module:
 
     touch modules/authX509/enable
 
 Then you must add it as an authentication source. Here is an
-example authsource.php
+example authsources.php entry:
 
     'x509' => array(
         'authX509:X509userCert',
@@ -52,8 +52,8 @@ example authsource.php
         'search.enable' => TRUE,
         'search.attributes' => array('uid', 'mail'),
         'search.base' => 'dc=example,dc=net',
-        'x509attributes' => array('UID' => 'uid'),
-        'ldapusercert' => array('userCertificate;binary'),
+        'authX509:x509attributes' => array('UID' => 'uid'),
+        'authX509:ldapusercert' => array('userCertificate;binary'),
     ),
 
 The configuration is the same as for the LDAP module, except for
@@ -62,16 +62,18 @@ 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')
+                 mappings are provided, any mapping 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
+                 be found. Default is userCertificate;binary. This can
+                 be set to NULL to avoid looking up the certificate in
+                 LDAP.
 
 
 Uploading certificate in LDAP
 -----------------------------
 
-Certificate are usually stored in LDAP as DER, in binary. Here is
+Certificates 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
@@ -84,8 +86,8 @@ Here is some LDIF to upload the certificate in the directory:
     userCertificate;binary:< file:///path/to/cert.der
 
 
-Supporting both certificate and login authentications
-=====================================================
+Supporting both certificate and login authentication
+====================================================
 
 In your Apache configuration, set SSLVerifyClient to optional. Then you
 can hack your metadata/saml20-idp-hosted.php file that way:

modules/authX509/lib/Auth/Source/X509userCert.php

@@ -46,7 +46,7 @@ class sspmod_authX509_Auth_Source_X509userCert extends SimpleSAML_Auth_Source {
 			$this->x509attributes =
 				$config['authX509:x509attributes'];
 
-		if (isset($config['authX509:ldapusercert']))
+		if (array_key_exists('authX509:ldapusercert', $config))
 			$this->ldapusercert =
 				$config['authX509:ldapusercert'];
 
@@ -142,18 +142,20 @@ class sspmod_authX509_Auth_Source_X509userCert extends SimpleSAML_Auth_Source {
 			return;
 		}
 
-		$dn = FALSE;
+		$dn = NULL;
 		foreach ($this->x509attributes as $x509_attr => $ldap_attr) {
 			/* value is scalar */
-			$value = $client_cert_data['subject'][$x509_attr];
-			SimpleSAML_Logger::info('authX509: cert '.
-			                        $x509_attr.' = '.$value);
-			$dn = $ldapcf->searchfordn($ldap_attr, $value, TRUE);
-			if ($dn !== FALSE)
-				break;
+			if (array_key_exists($x509_attr, $client_cert_data['subject'])) {
+				$value = $client_cert_data['subject'][$x509_attr];
+				SimpleSAML_Logger::info('authX509: cert '.
+				                        $x509_attr.' = '.$value);
+				$dn = $ldapcf->searchfordn($ldap_attr, $value, TRUE);
+				if ($dn !== NULL)
+					break;
+			}
 		}
 
-		if ($dn === FALSE) {
+		if ($dn === NULL) {
 			SimpleSAML_Logger::error('authX509: cert has '.
 			                         'no matching user in LDAP');
 			$state['authX509.error'] = "UNKNOWNCERT";
@@ -163,6 +165,16 @@ class sspmod_authX509_Auth_Source_X509userCert extends SimpleSAML_Auth_Source {
 			return;
 		}
 
+		if ($this->ldapusercert === NULL) { // do not check for certificate match
+			$attributes = $ldapcf->getAttributes($dn);
+			assert('is_array($attributes)');
+			$state['Attributes'] = $attributes;
+			$this->authSuccesful($state);
+
+			assert('FALSE'); /* NOTREACHED */
+			return;
+		}
+
 		$ldap_certs = $ldapcf->getAttributes($dn, $this->ldapusercert);
 		if ($ldap_certs === FALSE) {
 			SimpleSAML_Logger::error('authX509: no certificate '.