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TracFineGrainedPermissions
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Before Trac 0.11, it was only possible to define fine-grained permissions checks on the repository browser sub-system.
Since 0.11, there's a general mechanism in place that allows custom **permission policy plugins** to grant or deny any action on any kind of Trac resources, even at the level of specific versions of such resources.
Note that for Trac 0.12, `authz_policy` has been integrated as an optional module (in `tracopt.perm.authz_policy.*`), so it's installed by default and can simply be activated via the //Plugins// panel in the Trac administration module.
A great diversity of permission policies can be implemented, and Trac comes with a few examples.
Which policies are currently active is determined by a configuration setting in TracIni: e.g.
This lists the [#AuthzSourcePolicy] described below as the first policy, followed by the !DefaultPermissionPolicy which checks for the traditional coarse grained style permissions described in TracPermissions, and the !LegacyAttachmentPolicy which knows how to use the coarse grained permissions for checking the permissions available on attachments.
Among the possible optional choices, there is [#AuthzPolicy], a very generic permission policy, based on an Authz-style system. See [trac:source:branches/0.12-stable/tracopt/perm/authz_policy.py] for details.
Another popular permission policy [#AuthzSourcePolicy], re-implements the pre-0.12 support for checking fine-grained permissions limited to Subversion repositories in terms of the new system.
See also [trac:source:branches/0.12-stable/sample-plugins/permissions] for more examples.
- Install ConfigObj (still needed for 0.12).
- Copy authz_policy.py into your plugins directory (only for Trac 0.11).
- Put a authzpolicy.conf file somewhere, preferably on a secured location on the server, not readable for others than the webuser. If the file contains non-ASCII characters, the UTF-8 encoding should be used.
- Update your `trac.ini`:
1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section
1. add a new `[authz_policy]` section
1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section
Note that the order in which permission policies are specified is quite critical, as policies will be examined in the sequence provided.
A policy will return either `True`, `False` or `None` for a given permission check. `True` is returned if the policy explicitly grants the permission. `False` is returned if the policy explicitly denies the permission. `None` is returned if the policy is unable to either grant or deny the permission.
NOTE: Only if the return value is `None` will the next permission policy be consulted. If none of the policies explicitly grants the permission, the final result will be `False` (i.e. permission denied).
The `authzpolicy.conf` file is a `.ini` style configuration file:
- Each section of the config is a glob pattern used to match against a Trac resource
descriptor. These descriptors are in the form:
Resources are ordered left to right, from parent to child. If any component is inapplicable, `*` is substituted. If the version pattern is not specified explicitely, all versions (`@*`) is added implicitly
Example: Match the WikiStart page
Example: Match the attachment `wiki:WikiStart@117/attachment/FOO.JPG@*` on WikiStart
- Sections are checked against the current Trac resource descriptor IN ORDER of
appearance in the configuration file. '''ORDER IS CRITICAL'''.
- Once a section matches, the current username is matched against the keys
(usernames) of the section, '''IN ORDER'''. * If a key (username) is prefixed with a `@`, it is treated as a group. * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
The username will match any of 'anonymous', 'authenticated', <username></username> or '*', using normal Trac permission rules. || '''Note:''' Other groups which are created by user (e.g. by 'adding subjects to groups' on web interface page //Admin / Permissions//) cannot be used. See [trac:ticket:5648] for details about this missing feature ||
For example, if the `authz_file` contains:
and the default permissions are set like this:
Then:
* All versions of WikiStart will be viewable by everybody (including anonymous) * !PrivatePage will be viewable only by john * other pages will be viewable only by john and jack
Groups:
Then: - everything is blocked (whitelist approach), but - admins get all TRAC_ADMIN everywhere and - devs can view wiki pages.
Some repository examples (Browse Source specific):
Very fine grain repository access:
Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
Although possible with the !DefaultPermissionPolicy handling (see Admin panel), fine-grained permissions still miss those grouping features (see [trac:ticket:9573], [trac:ticket:5648]). Patches are partially available, see forgotten authz_policy.2.patch part of [trac:ticket:6680]).
You cannot do the following:
Permission groups are not supported either. You cannot do the following:
=== !AuthzSourcePolicy (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
At the time of this writing, the old fine grained permissions system from Trac 0.11 and before used for restricting access to the repository has been converted to a permission policy component, but from the user point of view, this makes little if no difference.
That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn. More information about this file format and about its usage in Subversion is available in the Path-Based Authorization section in the Server Configuration chapter of the svn book.
Example:
* '''/''' = ''Everyone has read access by default'' * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only'' * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
To activate fine grained permissions you specify the option in the section of trac.ini. If this option is set to null or not specified the permissions will not be used.
If you want to support the use of the `[`modulename`:/`some`/`path`]` syntax within the `authz_file`, add
where modulename refers to the same repository indicated by the `repository_dir` entry in the `[trac]` section. As an example, if the `repository_dir` entry in the `[trac]` section is , that would yield the following:
where the svn access file, , contains entries such as .
Note: Usernames inside the Authz file be the same as those used inside trac.
As of version 0.12, make sure you have !AuthzSourcePolicy included in the permission_policies list in trac.ini, otherwise the authz permissions file will be ignored.
The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
== Debugging permissions In trac.ini set:
And watch:
to understand what checks are being performed. See the sourced documentation of the plugin for more info.
See also: TracPermissions, TracHacks:FineGrainedPageAuthzEditorPlugin for a simple editor plugin.