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README for the Lockdown extension
Copyright © 2006 Daniel Kinzler
Licenses: GNU General Public Licence (GPL)
          GNU Free Documentation License (GFDL)
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The Lockdown extension implements a way to retrict access to specific
namespaces and special pages to a given set of user groups. This provides
a more fine grained security model than the one provided by the default 
$wgGroupPermissions and $wgNamespaceRestrictions settings.

<http://mediawiki.org/wiki/Extension:Lockdown>

The Lockdown extension was originally written by Daniel Kinzler in 2007
and is released under the GNU General Public Licence (GPL). 

The following pages about the security model used by MediaWiki per
default may be helpful to understand the instructions below:

* <http://www.mediawiki.org/wiki/Help:Managing_user_rights>
* <http://www.mediawiki.org/wiki/Manual:$wgGroupPermissions>


== WARNING: restricting read access not fully possible ==

Mediawiki is not designed to be a CMS, or to protect sensitive data. 
To the contrary, it was designed to be as open as possible. Thus it does
not support full featured, air-tight protection of private content.

This extension can be used to apply read-restrictions to namespaces,
limiting read access to specific groups. Note however that there may be
several ways in which data thusly protected may be "leaked" to the public:

* it is possible to include protected pages as templates, making them
  readable. This is addressed by the $wgNonincludableNamespaces setting
  introduced in MW 1.10, revision 19934.

* it is possible to export pages without having read-access to them using
  Special:Export. This has been fixed in MW 1.10, revision 19935.

* Content of newly created pages, and changes to existing pages, are shown
  in the RSS/Atom feeds provided by Special:recentchanges, without checking
  read permission. This has been fixed in MW 1.10, revision 19944.

* Read-Permission only applies to page content. "Hidden" pages are still
  listed in categories, Special:Allpages, etc. Also, changes to "hidden" 
  pages are still shown Special:Recentchanges, etc, including the edit
  summary.

* Excerpts of page content may be shown by Special:Search, regardless of
  read permission.

There are probably more "holes" in the read protection system. So, 
denying read access should be seens as a "nothing to see here, move
along", rather than a guarantee of secrecy.


== Installing ==

Copy the Lockdown directory into the extensions folder of your 
MediaWiki installation. Then add the following lines to your
LocalSettings.php file (near the end):

  require_once( "$IP/extensions/Lockdown/Lockdown.php" );

  $wgSpecialPageLockdown['Export'] = array('user');

  $wgNamespacePermissionLockdown[NS_PROJECT]['edit'] = array('user');

The settings for $wgSpecialPageLockdown and $wgNamespacePermissionLockdown
are just examples - see below for details.


== Configuration ==

Note that the Lockdown extension can only be used to *restrict* access,
not to *grant* it. If access is denied by some build-in setting of
MediaWiki, it cannot be allowed using the Lockdown extension.


=== $wgSpecialPageLockdown ===

$wgSpecialPageLockdown allows you to specify for each special page which
user groups have access to it. For example, to limit the use of 
Special:Export to logged in users, use this in LocalSettings.php:

    $wgSpecialPageLockdown['Export'] = array('user');

Note that some special pages "natively" require a specific permission.
For example, Special:Userrights, which can be used to assign user groups,
required the "userrights" permission (granted only to the "bureaucrat"
group per default). This restriction can not be overridden using the
Lockdown extension.

=== $wgActionLockdown === 

$wgActionLockdown allows you to specify for each actionwhich user groups
have access to it. For example, to limit the use of the history page to
logged in users, use this in LocalSettings.php:

    $wgActionLockdown['history'] = array('user');

Note that some actions can not be locked down this way. In particular, it
will not work for the ajax action.


=== $wgNamespacePermissionLockdown ===

$wgNamespacePermissionLockdown lets you restrict which user groups have
which permissions on which namespace. For example, to grant only members
of the sysop group write access to the project namespace, use this:

    $wgNamespacePermissionLockdown[NS_PROJECT]['edit'] = array('sysop');

Wildcards for either the namespace or the permission (but not both at once)
are supported. More specific definitions take precedence:

    $wgNamespacePermissionLockdown[NS_PROJECT]['*'] = array('sysop');
    $wgNamespacePermissionLockdown[NS_PROJECT]['read'] = array('*');

    $wgNamespacePermissionLockdown['*']['move'] = array('autoconfirmed');

The first two lines restrict all permissions in the project namespace to
members of the sysop group, but still allow reading to anyone. The third
line limits page moves in all namespaces to members of the autoconfirmed
group.

Note that this way, you cannot *grant* permissions that have not been
allowed by the build-in $wgGroupPermissions setting. The following does
*not* allow regular users to patrol edits in the main namespace:

    $wgNamespacePermissionLockdown[NS_MAIN]['patrol'] = array('user');

Instead, you would have to grant this right in $wgGroupPermissions first,
and then restrict it again using $wgNamespacePermissionLockdown:

    $wgGroupPermissions['user']['patrol'] = true;

    $wgNamespacePermissionLockdown['*']['patrol'] = array('sysop');
    $wgNamespacePermissionLockdown[NS_MAIN]['patrol'] = array('user');

Note that when restricting read-access to a namespace, the restriction can
easily be circumvented if the user has write access to any other namespace:
by including a read-protected page as a template, it can be made visible.
To avoid this, you would have to forbid the use of pages from that namespace
as templates, by adding the namespace's ID to $wgNonincludableNamespaces
(this feature was introduced in MediaWiki 1.10, revision 19934):

    $wgNamespacePermissionLockdown[NS_PROJECT]['read'] = array('user');
    $wgNonincludableNamespaces[] = NS_PROJECT;

PLEASE READ THE SECTION "WARNING: restricting read access not fully possible"
FOR MORE INFORMATION ABOUT THE LIMITATIONS OF RESTRICTING READ ACCESS!

