Extension:SimpleSAMLphp

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MediaWiki Stakeholders' Group Logo.svg この拡張機能は MediaWiki Stakeholders' Group のメンバーが保守しています。
PluggableAuth Icon.svg この拡張機能では、先に PluggableAuth 拡張機能をインストールする必要があります。
MediaWiki 拡張機能マニュアル
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SimpleSAMLphp
リリースの状態: 安定
実装 利用者識別
説明 Extends the PluggableAuth extension to provide authentication using SimpleSAMLphp.
作者 Cindy Cicalese, Robert Vogel
最新バージョン 4.5.2 (2020-04-12)
互換性ポリシー Master maintains backward compatibility.
MediaWiki 1.31+
PHP 5.3+
ライセンス MIT ライセンス
ダウンロード
  • $wgSimpleSAMLphp_GroupMap
  • $wgSimpleSAMLphp_UsernameAttribute
  • $wgSimpleSAMLphp_AttributeProcessorFactories
  • $wgSimpleSAMLphp_SyncAllGroups_LocallyManaged
  • $wgSimpleSAMLphp_SyncAllGroups_GroupAttributeName
  • $wgSimpleSAMLphp_EmailAttribute
  • $wgSimpleSAMLphp_GroupAttributeDelimiter
  • $wgSimpleSAMLphp_MandatoryUserInfoProviderFactories
  • $wgSimpleSAMLphp_SyncAllGroups_GroupNameModificationCallback
  • $wgPluggableAuth_Class
  • $wgSimpleSAMLphp_RealNameAttribute
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The SimpleSAMLphp extension extends the PluggableAuth extension to provide authentication using SimpleSAMLphp. It is primarily designed to support SP-initiated authentication flows.

インストール

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


設定

Values must be provided for the following mandatory configuration variables:

フラグ 既定 説明
$wgSimpleSAMLphp_InstallDir 既定値なし The path on the local server where SimpleSAMLphp is installed.
$wgSimpleSAMLphp_AuthSourceId 既定値なし The AuthSourceId to be used for authentication.
$wgSimpleSAMLphp_RealNameAttribute 既定値なし The name of the attribute(s) to be used for the user's real name. This may be a single attribute name or an array of attribute names. In the latter case, the attribute values will be concatenated with spaces between them to form the value for the user's real name.
$wgSimpleSAMLphp_EmailAttribute 既定値なし The name of the attribute to be used for the user's email address.
$wgSimpleSAMLphp_UsernameAttribute 既定値なし The name of the attribute to be used for the user's username.

In addition, the following optional configuration variables are provided:

フラグ 既定 説明 Since
$wgSimpleSAMLphp_GroupMap null Mapping from SAML attributes to MediaWiki groups of the form:

$wgSimpleSAMLphp_GroupMap = [ 'mediawiki group' => ['saml attribute' => ['group 1', 'group 2', '...']]];

No group mapping is performed if $wgSimpleSAMLphp_GroupMap is null.

$wgSimpleSAMLphp_GroupAttributeDelimiter null If the IdP returns the list of groups in a single string (e.g. "saml attribute" => [ "group 1,group 2,group 3" ] instead of "saml attribute" => [ "group 1", "group 2", "group 3" ]) this value can be set to split up the string. Be aware that in this case only the first element of the SAML attribute value is being evaluated. This setting applies to both group synchronization mechanisms "MapGroups" and "SyncAllGroups" 4.3
$wgSimpleSAMLphp_SyncAllGroups_GroupAttributeName "groups" If configured to use "SyncAllGroups", this SAML attribute will be read out 4.3
$wgSimpleSAMLphp_SyncAllGroups_LocallyManaged [ "sysop" ] If configured to use "SyncAllGroups", these local user groups will not be influenced by what is set in the SAML response 4.3
$wgSimpleSAMLphp_SyncAllGroups_GroupNameModificationCallback null If configured to use "SyncAllGroups", this can be used to change/normalize the groups coming from the IdP. Example see below. 4.3
$wgSimpleSAMLphp_AttributeProcessorFactories [

"...\\MapGroups::factory"

]

This can be used to set up the group synchronization mechanism and to add processing of arbitrary SAML response data. Example see below. The factory callback has the following signature:

callback(

\User $user,

array $attributes,

\Config $config,

SimpleSAML\Auth\Simple $saml )

: MediaWiki\Extension\SimpleSAMLphp\IAttributeProcessor

4.3

Define custom user info provider

If you want to modify any of the fields username, realname or email before login, for instance, if your SAML source does not provide an explicit username attribute and you want to use the email address without the domain for the username, you can configure a custom callback for $wgSimpleSAMLphp_MandatoryUserInfoProviderFactories. The factory method has the following signature:

factoryCallback( \Config $config ) : \MediaWiki\Extension\SimpleSAMLphp\IUserInfoProvider

For simple usecases one can use MediaWiki\Extension\SimpleSAMLphp\UserInfoProvider\GenericCallback, assuming your email attribute is called mail (if it's called something else, change the two instances of $attributes['mail'] to $attributes['YourEmailAttributeName']):

 $wgSimpleSAMLphp_MandatoryUserInfoProviderFactories['username'] = function( $config ) {
     return new \MediaWiki\Extension\SimpleSAMLphp\UserInfoProvider\GenericCallback( function( $attributes ) {
         if ( !isset( $attributes['mail'] ) ) {
             throw new Exception( 'missing email address' );
         }
         $parts = explode( '@', $attributes['mail'][0] );
         return strtolower( $parts[0] );
     } );
 };

Group mapping

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.

例:

  • 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: $wgSimpleSAMLphp_GroupMap = ['sysop' => ['groups' => ['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.

If a MediaWiki group does not exist, it will be created "on the fly" on first successful mapping of a user.

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.

Group mapping #2

Since version 4.3 one can also configure an alternative group synchronization mechanism. Besides the default "MapGroups" one can use "SyncAllGroups", which takes all groups from the SAML response and assign the user to them.

To do so, add the following to the LocalSettings.php:

$wgSimpleSAMLphp_AttributeProcessorFactories = [
	"MediaWiki\\Extension\\SimpleSAMLphp\\AttributeProcessor\\SyncAllGroups::factory"
];

If the IdP returns group names that are not suitable for the wiki, one can set up a callback to modify the group names. E.g. some IdP-Setups may return LDAP-DNs like "CN=Admin,OU=Groups,DC=SomeDomain". One could then specify in LocalSettings.php:

$wgSyncAllGroups_GroupNameModificationCallback = function ( $origGroupName ){
    return preg_replace( '#^CN=(.*?),OU=.*$#', '$1', $origGroupName );
}

Processing arbitrary data from the SAML response

The "attribute processors" can also be used to handle arbitrary data from the SAML response. In this case one must first create a new PHP class that implements the MediaWiki\Extension\SimpleSAMLphp\IAttributeProcessor interface. For convenience the base class MediaWiki\Extension\SimpleSAMLphp\AttributeProcessor\Base can be used, which has a proper factory callback and constructor implemented. An example

use MediaWiki\Extension\SimpleSAMLphp\AttributeProcessor\Base;

class SyncLanguage extends Base {
    public function run() {
        //Set gender on $this->user from a value in $this->attributes
    }
}

It then needs to be instantiated by using the $wgSimpleSAMLphp_AttributeProcessorFactories.

リリースノート

Version 4.5.2
  • fixed bug: Groups are not removed in MW if the attribute is not existing (T246351)
Version 4.5.1
  • fixed warning: $wgSimpleSAMLphp_GroupMap is not an array
  • improved loading UserInfo and Groups
  • improved tests
Version 4.5
  • added support for custom user info providers
  • updated to manifest version 2
Version 4.4
Version 4.3
  • Added support for attribute processors
  • Fixed bug in SAML attribute processing
  • Added PSR-4 compatible namespace
  • Dropped support for MW < 1.31
Version 4.2
  • Broke out username, real name, and email functions so they could be overridden in a subclass to allow custom rules
  • Coding style and directories
  • Improved debugging
Version 4.1
  • Implements PluggableAuthPopulateGroups hook to populate MediaWiki groups from SAML attributes. Thank you to Poikilotherm for contributing this functionality.
Version 4.0
  • Added optional error message to authenticate()
  • Bumped version number to synchronize with PluggableAuth and OpenID Connect extensions

デバッグ

SSO can be difficult to configure correctly, especially for first-time sysadmins tasked with connecting their new MediaWiki instance to the company's IdP. The PluggableAuth and SimpleSAMLphp extensions themselves are quite stable, so most issues are usually associated with configuration.

To start debugging, set $wgDebugLogFile to a filepath on your local system. You do not need to set $wgShowExceptionDetails to true; in fact, you probably shouldn't, due to security concerns.

Visit your wiki, and try logging in with PluggableAuth. Once you have encountered your error, visit the debug file and look for lines that start with [PluggableAuth] and [SimpleSAMLphp].

If there was an issue with authentication, the debug log will say [PluggableAuth] Authentication failed somewhere.

The SimpleSAMLphp extension works like this:

  1. User clicks on SSO login button on wiki.
  2. User is taken to Special:PluggableAuthLogin. It detects the wiki is using Extension:SimpleSAMLphp. SimpleSAMLphp (the software, not the extension) detects no login session has been set yet.
  3. Special:PluggableAuthLogin calls Extension:SimpleSAMLphp's authenticate() function, which calls SimpleSAMLphp's API to begin the authentication process.
  4. SimpleSAMLphp redirects user to the IdP's login page.
  5. After user successfully authenticates with IdP, it generates an assertion and redirects to your local SimpleSAMLphp instance's ACS (assertion consumer service) URL, which then redirects to the wiki's Special:PluggableAuthLogin.
  6. Special:PluggableAuthLogin now recognizes the session cookie and handles logging the user in.

If you are encountering a login redirect loop, the authentication process will never have a chance to log either an error or success message. This indicates that the call to SimpleSAMLphp's requireAuth() method never finishes, which means SimpleSAMLphp is trying to start the auth process all over again. This is usually because it is not detecting the login session despite it being set. Make sure you are not making common mistakes, such as not setting your SimpleSAMLphp store to a DB-based method, or putting your SimpleSAMLphp instance on a different domain than your wiki without a proper proxy. (For instance, if your SimpleSAMLphp instance is at the canonical domain saml.mywiki-sso.com but your wiki is located at my.wiki, the session will never be stored on my.wiki and Special:PluggableAuthLogin will redirect back to the IdP instead of logging the user in, creating a login loop.)

If you are encountering an error message on Special:PluggableAuthLogin after a successful redirect from the IdP, there is probably a PluggableAuth/SimpleSAMLphp misconfiguration in your LocalSettings.php. Check to see if you properly configured your attributes. The attributes may sometimes need to be URLs (such as if you are using Azure Active Directory).

既知のバグ

If you are using MediaWiki 1.27 or later with PluggableAuth 2.0 or later, problems have been observed when SimpleSAMLphp is configured to use phpsession for store.type. This may be due to phab:T147161. To fix this, use a different store type in the configuration of the SimpleSAMLphp software by adjusting simplesamlphp/config/config.php (see https://simplesamlphp.org/docs/stable/simplesamlphp-maintenance#section_2_3). For example, for SQLite, use:

'store.type' => 'sql',
'store.sql.dsn' => 'sqlite:/path/where/the/apache/user/can/write/sqlitedatabase.sq3',

For MySQL, use:

'store.type' => 'sql',
'store.sql.dsn' => 'mysql:host=xxx;port=xxx;dbname=xxx',
'store.sql.username' => 'xxx',
'store.sql.password' => 'xxx',

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