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MediaWiki Shibboleth extension

The Shibboleth extension extends the PluggableAuth extension to provide authentication using Shibboleth Apache module.

Recommended MediaWiki version: 1.29+

Required packages and settings

In order to use Shibboleth Apache module as an authentication method in your wiki, you need a working Shibboleth Service Provider (SP).

Install Shibboleth Apache modul on Debian/Ubuntu linux:

  • sudo apt install libapache2-mod-shib2
  • sudo a2enmod shib2
  • sudo systemctl restart apache2

Apache vhost konfig

<Location /index.php/*:PluggableAuthLogin>
	AuthType shibboleth
	ShibRequestSetting applicationId default
	ShibRequestSetting requireSession true
	Require valid-user
</Location>

Apache vhost konfig FastCGI (FPM)

You should replace ShibRequestSetting applicationId default with ShibUseHeaders On.

<Location /index.php>
  <If "%{QUERY_STRING} =~ /title=(.+):PluggableAuthLogin/">
  AuthType shibboleth
  ShibRequestSetting requireSession true
  Require valid-user
  ShibUseHeaders On
  </If>
</Location>

Installation

This extension requires the PluggableAuth extension and Shibboleth to be installed first.

  • Download and place the file(s) in a directory called Shibboleth in your extensions/ folder.
  • Add the following code at the bottom of your LocalSettings.php:
wfLoadExtension( 'Shibboleth' );
  • Configure as required
  • Done! Navigate to Special:Version on your wiki to verify that the extension is successfully installed.

Configure

Values must be provided for the following mandatory configuration variables:

Flag Default Description
$wgShibboleth_Username no default value The name of the attribute to be used for the user's username.
$wgShibboleth_Email no default value The name of the attribute to be used for the user's email address.
$wgShibboleth_DisplayName no default value The name of the attribute(s) to be used for the user's real name.
$wgShibboleth_Logout_Base_Url no default value Single Logout (SLO) base URL
$wgShibboleth_Logout_Target_Url no default value Single Logout (SLO) target URL

In addition, the following optional configuration variable is provided:

Flag Default Description
$wgShibboleth_GroupMap null Mapping from SAML attributes to MediaWiki groups of the form: $wgShibboleth_GroupMap = array('attr_name' => 'groups','sysop' => 'wiki_admin','bureaucrat' => 'wiki_editor', '...'); No group mapping is performed if $wgSimpleSAMLphp_GroupMap is null.
$wgShibboleth_RequireGroup true Weather missing the group SAML attribute, the attr_name in the $wgShibboleth_GroupMap , will invalidate the session or not. Set to false to let in users without any group mapping, in that case users will be mapped to the default unprivileged MediaWiki groups.

Group mapping

IMPORTANT The extentsion supports only the sysop and bureaucrat groups.

Use case: your SAML IdP reads groups from LDAP or Database and stores this information inside an attribute of the SAML response. You want to use this to map MediaWiki groups to users belonging to some known groups given by your IdP.

Example:

  • Your IdP sends an attribute named "groups" with a list of names like "administrator", "student", "teacher", ... in the SAML response after authentication.
  • All users that have the value "administrator" in the "groups" attribute shall be mapped to the MediaWiki "sysop" group to give them admin rights within your MediaWiki instance.
  • Create a group map in your LocalSettings.php as follows: $wgShibboleth_GroupMap = array('attr_name' => 'groups','sysop' => 'administrator',);

You can come up with rather complex mappings that fit your needs. If you have more than one attribute from SAML, just add it to the array with the array of values you like to map.

HINT: If a user belongs to a MediaWiki group that is no longer mapped to that user (for example, by losing the group membership in the SAML user data source), the user will be removed from that MediaWiki group at next log in. In that way you can mass remove groups from SAML and their memberships, too - just scramble the mapping values so they don't match the SAML response, but don't mess up the MediaWiki group name.

Single Logout (SLO)

Shibboleth Single Logout (SLO) URL structure

$wgShibboleth_Logout_Base_Url . Shibboleth.sso/Logout?return= . $wgShibboleth_Logout_Target_Url

https://wiki.example.org/Shibboleth.sso/Logout?return=https://wiki.example.org/index.php