Extension:CentralAuth

MediaWiki extensions manual

CentralAuth Release status: stable
Implementation	User identity, Database, Special page, API
Description	Allows to merge accounts into global accounts
Author(s)	Brion Vibber
MediaWiki	1.11+
License	GPL
Download	Download snapshot (Git master) Git [?]: repo summary browse file tree commit history code review
Parameters $wgCentralAuthDatabase $wgCentralAuthAutoNew $wgCentralAuthAutoMigrate $wgCentralAuthStrict $wgCentralAuthDryRun $wgCentralAuthCookies $wgCentralAuthCookieDomain $wgCentralAuthCookiePrefix $wgCentralAuthAutoLoginWikis
Added rights centralauth-admin, centralauth-merge, centralauth-unmerge, centralauth-lock. centralauth-oversight, centralauth-rename, globalgrouppermissions, globalgroupmembership
Hooks used AuthPluginSetup AddNewAccount AbortNewAccount UserLoginComplete UserLoadFromSession UserLogout UserLogoutComplete GetCacheVaryCookies GetPreferences UserArrayFromResult UserGetEmail UserGetEmailAuthenticationTimestamp UserSetEmail UserSetEmailAuthenticationTimestamp UserGetRights UserSetCookies UserLoadDefaults getUserPermissionsErrorsExpensive MakeGlobalVariablesScript SpecialPasswordResetOnSubmit RenameUserWarning RenameUserPreRename RenameUserComplete
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Issues:	Open tasks · Report a bug

CentralAuth allows global accounts shared between projects. This extension adds seven new special pages—Special:AutoLogin (unlisted special page), Special:CentralAuth, Special:GlobalGroupMembership, Special:GlobalGroupPermissions, Special:WikiSets, Special:GlobalUsers and Special:MergeAccount.

Warning: CentralAuth was designed specifically for Wikimedia projects which already had millions of accounts that needed to be merged into a global table. If you are starting a new wiki farm from scratch and have no need to merge existing accounts into a global table, it is much easier to set up global accounts using $wgSharedDB rather than using CentralAuth. However, this provides no solution to the single-sign-on feature (sign-in on one wiki, like wikipedia.org, automatically makes the user signed-in to e.g. a shared repository under a different, shared domain, like commons.wikimedia.org), nor global account locking.

CentralAuth development is closely tied to the MediaWiki core development trunk. Therefore, if you download the latest CentralAuth version, it may not work with older versions of MediaWiki. In general, for the best results, it may be a good idea to use a trunk version of MediaWiki when using this extension.

Installation

See the setup section below for prerequisites to using CentralAuth. Then follow these instructions when you are ready to activate CentralAuth:

1. Download the latest snapshot and extract it to your extensions directory.
2. Pick a database and create the CentralAuth database tables. You can use an existing database or create a new one; the extension by default uses a database named centralauth (see $wgCentralAuthDatabase below). use this database then run central-auth.sql.
   • If you use Extension:AntiSpoof you'll need to create a global spoofuser table (to block new usernames that look similar to existing usernames in any wiki). One way to do this is dump the spoofuser table from the local wiki's database and import it into the new $wgCentralAuthDatabase.
3. Add require_once "$IP/extensions/CentralAuth/CentralAuth.php"; to LocalSettings.php for each of your wikis, or in another PHP file that is included in LocalSettings.php on each of your wikis.
4. The extension should be now active.

Here are sample shell and SQL commands to create the centralauth database, copy the spoofuser table to it, and migrate existing user data to it. Replace $wgDBname and $wgDBuser with the values for your own wiki installation.

$ cd extensions/CentralAuth
$ mysql -u root -p
(enter password for root SQL user)

CREATE DATABASE centralauth;
USE centralauth;
SOURCE central-auth.sql
GRANT all on centralauth.* to '$wgDBuser'@'localhost';
quit

$ mysqldump -u $wgDBuser -p $wgDbName spoofuser > /tmp/spoofuser.temp
$ mysql -u $wgDBuser  -p centralauth < /tmp/spoofuser.temp
$ php maintenance/migratePass0.php
$ php maintenance/migratePass1.php

Walkthrough is a more user-friendly setup than the instructions below.

Setup

First, you'll need to configure your wiki family using $wgConf, or CentralAuth can't be used for your wiki family. This includes setting $wgLocalDatabases and assigning it to $wgConf->wikis, and $wgConf->settings (minimum is $wgCanonicalServer, $wgServer and $wgArticlePath). Follow the examples carefully. Make sure that you put the configuration code after the require_once "$IP/extensions/CentralAuth/CentralAuth.php"; line in LocalSettings.php. If you are creating a new wiki family, bear in mind that it may be easier if the databases for the wikis in each group have the same suffix (e.g. hypothetical databases enwiki, dewiki, frwiki, etc., pertaining to wikis belonging to the same group, all have the suffix "wiki").

After installing the extension, you have to gather some data in the CentralAuth database. In order to retroactively set up global accounts, you will have to run the migratePass0.php and migratePass1.php scripts. The first one stores information about your wikis in the CentralAuth database, while the second one uses automatic migration heuristics to generate global accounts. A user can merge their accounts manually via Special:MergeAccount. Dry runs can be used for testing purposes.

To enable global groups, you will have to make an entry into the global_group_permissions table in your CentralAuth database, with ggp_group='steward' and (for access to the group management interface) ggp_permission=globalgrouppermissions. A sample query that is recommended to use is: INSERT INTO global_group_permissions (ggp_group,ggp_permission) VALUES ('steward','globalgrouppermissions'), ('steward','globalgroupmembership');. Then, run migrateStewards.php to promote local stewards to global steward status.

There are various settings you may wish to modify (e.g. whether to provide single sign-on across a whole domain) listed in CentralAuth.php. In particular, you will want to override the default value of $wgCentralAuthDatabase if your CentralAuth database is named something other than 'centralauth'. Make sure you put such settings after the require_once line in LocalSettings.php, e.g.:

require_once "$IP/extensions/CentralAuth/CentralAuth.php";
$wgCentralAuthDatabase = 'mycentralauthdatabase';

"SUL2" behavior

In July 2013 WMF changed its approach to logging users into multiple wikis. When configured for this new approach, after successful login and account creation CentralAuth redirects to Special:CentralLogin/start?token=somevalue on a "central login wiki", which sets cookies on that wiki and then redirects back to the logged-into wiki. It omits the "login/account creation success" page, instead redirecting back to the "returnto" page that the user was originally on. It places 1x1 pixel images in the footer of that page, in place of the icons formerly used on the "login/account creation success" page.

The settings for this are, roughly,

# General CentralAuth configuration
$wgCentralAuthCookies = true;
$wgCentralAuthAutoNew = true;
$wgCentralAuthDatabase = 'centralauthDatabaseName'; // default is 'centralauth'
$wgCentralAuthAutoMigrate = true;
#$wgCentralAuthCookieDomain = '.example.org';
$wgCentralAuthAutoLoginWikis = array(
    # Mapping from domain name to wiki id for other wikis to automatically login into
);

# Create the local account on pageview, set false to require a local login to create it.
$wgCentralAuthCreateOnView = true;

# Activates the redirect to the "central login wiki"
$wgCentralAuthLoginWiki = 'WikiIdOfLoginWiki';

# Skips the "login success" page
$wgCentralAuthSilentLogin = true;

# Deprecated, will be removed soon.
$wgCentralAuthUseOldAutoLogin = false;

$wgCentralAuthLoginWiki is the id (usually the database-name) of the wiki to which CentralAuth will redirect on login and create account.

$wgCentralAuthAutoNew means account creation will create a new global account.

Simulating SUL2 behavior on a single-instance development machine

You can simulate this new behavior on a single-instance development machine. You can set $wgCentralAuthLoginWiki = $wgDBname) so CentralAuth makes its HTTP redirect requests to your same local wiki. This will not exercise central login properly, but will activate its "returnto" behavior. CentralAuth will still use its own 'centralauth' database to store global user names.

To determine the URL on the login wiki, CentralAuth uses WikiMap which assumes a wiki farm has been configured using $wgConf. Configuration setup (in SiteConfiguration.php) is very flexible; one way to set up a dummy single-wiki $wgConf in LocalSettings.php is:

// You can't just set wgConf values to the globals defined in Setup.php for your
// local wiki, because it hasn't run yet.  You could hard-code $wgConf settings
// here, but instead we set the wgConf values in a hook that runs later.
$wgHooks['SetupAfterCache'][] = function() {
    global $wgConf, $wgDBname,
        $wgServer, $wgCanonicalServer, $wgArticlePath;
    $wgConf->suffixes = array( $wgDBname );
    $wgConf->settings['wgServer'][$wgDBname] = $wgServer;
    $wgConf->settings['wgCanonicalServer'][$wgDBname] = $wgCanonicalServer;
    $wgConf->settings['wgArticlePath'][$wgDBname] = $wgArticlePath;
    return true;
};

This is in addition to the settings in #"SUL2" behavior above.

Cache issues

You do not need to use "CREATE TABLE centralauth.objectcache LIKE enwiki.objectcache" if you use MediaWiki version 1.19 or higher. The table is already created during the setup of your wiki.

Setting up CentralAuth will require all your wikis to use the same cache server. If they all use memcached it shouldn't be a problem, however if they are configured with the default setting (CACHE_NONE) and use different databases (or prefixes) it won't work (specifically, single logins do not work). Copy the objectcache table's structure to the CentralAuth database. This can be done by using a SQL command such as the following (which assumes your CentralAuth database is named centralauth and that your wiki is named enwiki):

CREATE TABLE centralauth.objectcache LIKE enwiki.objectcache

You also need to configure the following:

$wgSharedDB     = 'centralauth'; // or whatever database you use for central data
$wgSharedTables = array( 'objectcache' ); // remember to copy the table structure's to the central database first
$wgMainCacheType = CACHE_DB; // Tell mediawiki to use objectcache database instead of nothing

Configuration

Configuration settings in CentralAuth.php

parameter	default	comment
$wgCentralAuthDatabase	'centralauth'	Database name you keep central auth data in. If this is not on the primary database connection, don't forget to also set up $wgDBservers to have an entry with a groupLoads setting for the 'CentralAuth' group. Alternatively you can use $wgLBFactoryConf to set up an LBFactoryMulti object. To use a database with a table prefix, set this variable to "{$database}-{$prefix}".
$wgCentralAuthAutoNew	false	If true, new account registrations will be registered globally if the username hasn't been used elsewhere.
$wgCentralAuthAutoMigrate	false	If true, existing unattached accounts will be automatically migrated if possible at first login. Any new account creations will be required to attach. If false, unattached accounts will not be harassed unless the individual account has opted in to migration.
$wgCentralAuthAutoMigrateNonGlobalAccounts	false	If true, existing unattached accounts where no global account exists will be compared to see if a merge can be made based on passwords and emails with no clashes (all accounts merge). This was formerly controlled by $wgCentralAuthAutoMigrate
$wgCentralAuthStrict	false	If true, remaining accounts which have not been attached will be forbidden from logging in until they are resolved.
$wgCentralAuthDryRun	false	If true, merging won't actually be possible through the Special:MergeAccount interface.
$wgCentralAuthCookies	false	If true, global session and token cookies will be set alongside the per-wiki session and login tokens when users log in with a global account. This allows other wikis on the same domain to transparently log them in.
$wgCentralAuthLoginWiki	false	Database name of a central login wiki. This is an alternative to directly setting cross-domain cookies for each wiki in $wgCentralAuthAutoLoginWikis. If set, a single login wiki will use a session/cookie to handle unified login sessions across wikis. On login, users will be redirected to the login wiki's Special:CentralLogin/login page and then redirected to Special:CentralLogin back on the originating wiki. In the process, the central login wiki cookie and session will be set. As the user accesses other wikis, the login wiki will be checked via JavaScript to check login status and set the local session and cookies. This requires $wgCentralAuthCookies.
$wgCentralAuthCookieDomain		Domain to set global cookies for. For instance, '.wikipedia.org' to work on all wikipedia.org subdomains instead of just the current one. Leave blank to set the cookie for the current domain only, such as if all your wikis are hosted on the same subdomain.
$wgCentralAuthCookiePrefix	'centralauth_'	Prefix for CentralAuth global authentication cookies.
$wgCentralAuthCookiePath	'/'	Path for CentralAuth global authentication cookies. Set this variable if you want to restrict cookies to a certain path within the domain specified by $wgCentralAuthCookieDomain.
$wgCentralAuthAutoLoginWikis	array()	List of wiki IDs which should be called on login to try to set third-party cookies for the global session state. The wiki ID is typically the database name, except when table prefixes are used, in which case it is the database name, a hyphen separator, and then the table prefix. This allows a farm with multiple second-level domains to set up a global session on all of them by hitting one wiki from each domain (en.wikipedia.org, en.wikinews.org, etc). Done by accessing Special:CentralAutoLogin/start on each wiki. If empty, no other wikis will be hit. The key should be set to the cookie domain name.
$wgCentralAuthAutoCreateWikis	array()	List of wiki IDs on which an attached local account should be created automatically when the global account is created. The wiki ID is typically the database name, except when table prefixes are used, in which case it is the database name, a hyphen separator, and then the table prefix.
$wgCentralAuthLoginIcon	false	Local filesystem path to the icon returned by Special:CentralAutoLogin Should be a 20x20px PNG.
$wgCentralAuthPrefsForUIReload	array( 'skin', 'language', 'thumbsize', 'underline', 'stubthreshold', 'showhiddencats', 'justify', 'numberheadings', 'editondblclick', 'editsection', 'editsectiononrightclick', 'usenewrc', 'extendwatchlist', );	User preferences for which we should recommend reloading the page after a successful central login query. If you need to do something more complicated than just $user->getOption( $pref ) !== User::getDefaultOption( $pref ), use the hook CentralAuthIsUIReloadRecommended.
$wgCentralAuthCookiesP3P	true	Specify a P3P header value to be used when setting CentralAuth cookies on the login wiki ($wgCentralAuthLoginWiki). When set true, a invalid policy (lacking all required tokens) will be sent that none the less serves to allow current versions of IE with the default privacy settings to see the cookies in the auto-login check. Set false to disable sending the P3P header altogether. Note this will likely break the auto-login check in IE, unless the header is being set globally elsewhere (e.g. in the webserver). Otherwise, whatever string is assigned here will be sent as the value of the P3P header. @var bool|string
$wgCentralAuthCreateOnView	false	If true, local accounts will be created for active global sessions on any page view. This is kind of creepy, so we're gonna have it off for a little bit. With other default options, the local autocreation will be held off until an active login attempt, while global sessions will still automatically log in those who already have a merged account.
$wgCentralAuthRC	array()	Array of settings for sending the CentralAuth events to the RC Feeds @example $wgRCFeeds['example'] = array( 'uri' => "udp://localhost:1336", );
$wgCentralAuthLockedCanEdit	array()	List of local pages global users may edit while being globally locked.
$wgDisableUnmergedEditing	false	Disable editing for non-global accounts (except on NS_USER_TALK and NS_PROJECT_TALK)
$wgCentralAuthWikisPerSuppressJob	10	Size of wikis handled in one suppress user job. Keep in mind that one wiki requires ~10 queries.
$wgCentralAuthReadOnly	false	Like $wgReadOnly, used to set extension to database read only mode @var bool
$wgCentralAuthUseEventLogging	false	Use the EventLogging extension to measure various activities
$wgCentralAuthPreventUnattached	false	Don't allow new unattached accounts to be created @var bool
$wgCentralAuthEnableUserMerge	false	Whether to enable the global user merge tool This only controls the availability of the special page, and does not prevent LocalUserMergeJobs from running on the given wiki. @var bool
$wgCentralAuthEnableGlobalRenameRequest	false	Feature flag for Special:GlobalRenameRequest @var bool
$wgCentralAuthCheckSULMigration	false	Enable special logic to attempt to ease the user facing impact of forced user migrations. @var bool

Use

Allows for a single-user login (SUL) system using MediaWiki's AuthPlugin system. User creation and login is done globally using one central user table across all wikis. Note that local user accounts are automatically created on account creation/login however.

This extension also implements global user groups, to which global accounts can belong to.

Functions

SUL

A user with an account on more than one wiki may use Special:MergeAccount to create their global user account, which can then be used on any wiki.

Global users

Screenshot of CentralAuth interface on Wikimedia, showing lock/hide interface.

A global account can be locked or hidden by a user with the centralauth-lock and centralauth-oversight permissions, respectively, given to the local group 'stewards' by default. A locked global account will be immediately logged out of any session on any wiki it is currently logged in to, and logins fail with an "incorrect password" error. A hidden global account's username is not visible in any logs except the global account log.

Users with the centralauth-unmerge permission (again, given to stewards by default) can undo a merging of a global account, where the passwords are all reset back to the pre-merge setting.

Warning: Account renames using Extension:Renameuser have to be done locally on every wiki.

Wiki sets

A wiki set is a group of wikis specified by a user with the globalgrouppermissions right. Sets can be opt-in (wikis are not in it by default) or opt-out (wikis are in it unless opted out).

Global user groups

Once you have enabled global user groups as described in the installation section, a migrated steward can use the Special:GlobalGroupPermissions interface to configure global user groups, and their rights. A global user group is active on all wikis (the users in it have its rights on all the wikis) by default, unless the group has been specified to only be active on a specific wiki set (the users in the group only have the rights if they are on a wiki in the set). Global group permissions are not listed at Special:ListUsers, but instead Special:GlobalUsers. They are assigned by a user with the globalgroupmembership permission (by default the global group stewards), and give the specified rights to the user even if the local rights defined by $wgGroupPermissions do not do so.

Licensing and downloads

The extension is available under the GNU General Public License 2.0 or later, and can be downloaded from Git, or accessed via the web-based viewer.

The software is provided as-is. Updates will be made according to the needs of Wikimedia wikis; or where critical vulnerabilities are discovered.

Hooks

This extension adds one new hook:

• CentralAuthWikiList

API

See Extension:CentralAuth/API.

See also

• m:Single login specifications
• m:Help:Unified login
• $wgSharedDB
• Global session threat assessment
• en:Wikipedia:Integrated watchlists
• CentralAuth control flow

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