Access Control Lists (ACL)

DokuWiki – like most wikis – is very open by default. Everyone is allowed to create, edit and delete pages. However sometimes it makes sense to restrict access to certain or all pages. This is when Access Control Lists (ACL) come to play. This page should give you an overview of how ACLs work in DokuWiki and how they are configured.

WARNING: DokuWiki's ACL feature has now been included for some time and should be pretty stable. However, if you are concerned about the risk of unauthorized users accessing information in your wiki, you should never put it on a computer accessible from the Internet…

ACLs can be enabled in the installer and an initial ACL policy is set there as well. To manually enable ACLs, switch on the useacl option and copy the example files conf/acl.auth.php.dist and conf/users.auth.php.dist to conf/acl.auth.php and conf/users.auth.php respectively.

There are a few more config options and features that relate to authentication, user registration and ACL setup. Please check their respective wiki pages to get more information:

• Config option useacl – enable ACL usage
• Config option superuser – setup superusers with ACL granting rights
• Config option disableactions – allows you to disable open registration
• Config option defaultgroup – the default group to which new users are added
• User Manager – managing users
• Authentication Backends – identify users from different data sources
• FAQ: How to disable open user registration

Access restrictions can be bound to pages and namespaces. There are seven permissions: none, read, edit, create, upload, delete and admin. Each higher permission contains the lower ones, with read being the lowest and delete the highest one. You should note that create, upload and delete permissions can only be assigned to namespaces.

Rules that were set to namespaces apply on media namespaces as well as for page namespaces.

When DokuWiki checks which rights it should give to a user, it uses all rules matching the user's name or the groups he or she is in. The rule that provides a user's permission is chosen according to the following process:

• Rules which match closer to the namespace:page are preferred over rules which match further away – we call this “specific matching”.
• When more than one rule matches at the same level, the rule giving the highest access level is preferred.

Users are in the groups they were assigned to in the user manager (or the auth backend). However there are two groups that are somewhat special:

• @ALL. Everyone, even users not logged in, is a member of the ALL group. You can use this group to restrict access for all users (as a default setting) and then relax the permissions for some selected users.
• @user. All self-registered users are by default automatically a member of the group 'user'. Use this to give permissions to 'logged-in' users. The name of this group is configured through the defaultgroup option. Unlike the virtual “ALL” group, the “user” group is a real group to which all users are added automatically when using the plain auth backend. If you use a different backend you need to use the groups provided by this backend.

Groups are represented internally and in the ACL manager by a prepended @ character to the group name.

To easily add new or change existing access rules, you should use the ACL Manager which is available from the Administration menu. A detailed description of its interface can be found here.

Basically there are three steps to add a new ACL rule:

1. select the namespace or page to restrict from the upper left tree navigation
2. choose to whom the ACL rule should apply
   • by selecting a known group or user from the dropdown menu
   • or by selecting “User:” or “Group:” and entering the group or user name in the field
3. set the appropriate permission

Existing rules can be modified or deleted in the table at the bottom of the ACL manager.

In this section we will explain how access rules work, using a fictional example setup that looks like this in the ACL manager:

Let's have a look at each line:

1. This sets permission for everyone in the main namespace, allowing everybody to edit and create pages. However upload is not allowed.
2. User bigboss is given full rights.
3. Now the access for the devel namespace is restricted. Nobody is allowed to do anything.
4. Well not nobody really – we give members of the devel group full rights here.
5. And of course bigboss is allowed, too – and he's the only one who can delete uploaded files.
6. And the marketing team may read everything in the devel namespace, but read only.
7. However the devel guys don't want their boss to see the funstuff page – remember exact pagematches override namespace permissions.
8. And finally the marketing guys are allowed to edit the devel:marketing page as well.
9. Then the permissions for the namespace marketing are set. All members of the marketing group are allowed to upload there - other users will be matched by line 1 so they can still create and edit. bigboss inherits his rights from line 2 so he can upload and delete files.
10. The last line finally restrict the start page to readonly for everyone, only superusers will be able to ever edit that page.

Let's have a look at a second example to better understand specific matching:

This time we look what rules will match for different users when trying to access the page private:bobspage.

1. abby, a regular user
   • three rules match, #1, #2, #4
   • rule #4 is closest, it matches at the namespace level so it takes precedence over the other three
   • abby's permissions level is 0
2. bob, a regular user
   • four rules match, #1, #2, #4, #6
   • rule #6 wins as its an exact match
   • bob's permission level is 16
3. bob forgets to login and tries to access his page
   • two rules match, #1 & #4
   • rule #4 is closer, it wins
   • bob's permission level while not logged in is 0
4. charlie, a staff member
   • five rules match, #1 - #5
   • two rules match at namespace level, #5 gives charlie the higher permission so it wins
   • charlie's permission level is 16

Note rule #5 which appears to duplicate rule #3, without it staff members wouldn't be able to access the private namespace as rule #4 would keep them out.

Access restrictions are saved in a file called conf/acl.auth.php, which should be writable by the webserver if you want to use the ACL admin interface described above. It is not recommended to edit this file manually. Use the admin interface instead.

Empty lines and shell-style comments are ignored. Each line contains 3 whitespace separated fields:

• The resource to restrict. This can either be a pagename or a namespace. Namespaces are marked by an additional asterisk (see examples below).
• A group or user name. Groupnames are marked by a leading @ character.
• A permission level (see below).

There are 7 permission levels represented by an integer. Higher levels include lower ones. If you can edit you can read, too. However the admin permission of 255 can not be used in the conf/acl.auth.php file. It is only used internally by matching against the superuser option.

Here is an example setup matching the first example given above:

*                     @ALL        4
*                     bigboss    16
devel:*               @ALL        0
devel:*               @devel      8
devel:*               bigboss    16
devel:*               @marketing  1
devel:funstuff        bigboss     0
devel:marketing       @marketing  2
marketing:*           @marketing  8
start                 @ALL        1

Please note, that order does not matter in the file. The file is parsed as whole, then a perfect match for the current page/user combo is searched for. When a match is found further matching is aborted. If no match is found, group permissions for the current page are checked. If no match is found the check continues in the next higher namespace.

Note: To configure users or groups with special chars (like whitespaces) you need to URL escape them. This only applies to specialchars in the lower 128 byte range. The ACL file uses UTF-8 encoding so any multibytechars can be written as is.

Note: The delete permission affects media files only. Pages can be deleted (and restored) by everyone with at least edit permission. Someone who has upload permissions but no delete permissions can not overwrite existing media files anymore.

It is possible to use user wildcards in the ACLs. This can be useful for Wikis with many registered users, if you want to give each user a personal namespace where only he/she has write access, and you don't want to edit the ACLs for each user. To accomplish that %USER% is replaced by the username of the currently logged in user. In the following example a logged in user gains upload/delete permissions for the people:<username> page and the people:<username> namespace.

people:%USER%    %USER%    16
people:%USER%:*  %USER%    16

Note: The wildcard was recently changed from @ to % – if you are upgrading from an older version you need to adjust your ACL setup accordingly.