Changes between Initial Version and Version 1 of TracFineGrainedPermissions

Oct 17, 2016 3:38:00 PM (5 years ago)



  • TracFineGrainedPermissions

    v1 v1  
     1= Fine grained permissions =
     2[[PageOutline(2-5, Contents, floated)]]
     5There is a general mechanism in place that allows custom **permission policy plugins** to grant or deny any action on any kind of Trac resource, even at the level of specific versions of such resources.
     7That mechanism is `authz_policy`, which is an optional module in `tracopt.perm.authz_policy.*`, so it is installed by default. It can be activated via the //Plugins// panel in the Trac administration module.
     9== Permission Policies ==
     11A great diversity of permission policies can be implemented and Trac comes with a few examples.
     13Which policies are currently active is determined by a configuration setting in TracIni:
     17permission_policies = ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     19This lists the [#ReadonlyWikiPolicy] which controls readonly access to wiki pages, 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.
     21Among the optional choices, there is [#AuthzPolicy], a very generic permission policy, based on an Authz-style system. See
     22[trac:source:branches/1.0-stable/tracopt/perm/] for details.
     24Another 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.
     26See also [trac:source:branches/1.0-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
     28=== !AuthzPolicy ===
     29==== Configuration ====
     30* 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.
     31* Update your `trac.ini`:
     32  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section:
     36permission_policies = AuthzPolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     38  1. add a new `[authz_policy]` section:
     41authz_file = /some/trac/env/conf/authzpolicy.conf
     43  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     46tracopt.perm.authz_policy.* = enabled
     49==== Usage Notes ====
     51Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
     53A 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.
     55NOTE: 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.
     57The `authzpolicy.conf` file is a `.ini` style configuration file:
     60john = WIKI_VIEW, !WIKI_MODIFY
     61jack = WIKI_VIEW
     62* =
     64* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
     66<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
     69Resources are ordered left to right, from parent to child. If any component is inapplicable, `*` is substituted. If the version pattern is not specified explicitly, all versions (`@*`) is added implicitly. Example: Match the WikiStart page:
     77Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     86* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of appearance in the configuration file. '''ORDER IS CRITICAL'''.
     88* Once a section matches, the current username is matched against the keys (usernames) of the section, '''IN ORDER'''.
     89  * If a key (username) is prefixed with a `@`, it is treated as a group.
     90  * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
     92The username will match any of 'anonymous', 'authenticated', <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 #5648] for details about this missing feature. ||
     94For example, if the `authz_file` contains:
     97* = WIKI_VIEW
     100john = WIKI_VIEW
     101* = !WIKI_VIEW
     103and the default permissions are set like this:
     105john           WIKI_VIEW
     106jack           WIKI_VIEW
     107# anonymous has no WIKI_VIEW
     111  * All versions of WikiStart will be viewable by everybody, including anonymous
     112  * !PrivatePage will be viewable only by john
     113  * other pages will be viewable only by john and jack
     118admins = john, jack
     119devs = alice, bob
     122@admins = TRAC_ADMIN
     123@devs = WIKI_VIEW
     124* =
     127@admins = TRAC_ADMIN
     128* =
     132- everything is blocked (whitelist approach), but
     133- admins get all TRAC_ADMIN everywhere and
     134- devs can view wiki pages.
     136Some repository examples (Browse Source specific):
     138# A single repository:
     140john = BROWSER_VIEW, FILE_VIEW
     141# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
     143# The default repository (requires Trac 1.0.2 or later):
     145john = BROWSER_VIEW, FILE_VIEW
     146# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
     148# All repositories:
     150jack = BROWSER_VIEW, FILE_VIEW
     151# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     154Very granular repository access:
     156# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     158john = BROWSER_VIEW, FILE_VIEW
     160# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     162john = BROWSER_VIEW, FILE_VIEW
     164# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     166john = BROWSER_VIEW, FILE_VIEW
     168# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     170john = BROWSER_VIEW, FILE_VIEW
     173Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     175==== Missing Features ====
     176Although possible with the !DefaultPermissionPolicy handling (see Admin panel), fine-grained permissions still miss those grouping features (see [trac:ticket:9573 #9573], [trac:ticket:5648 #5648]). Patches are partially available, see authz_policy.2.patch, part of [trac:ticket:6680 #6680].
     178You cannot do the following:
     181team1 = a, b, c
     182team2 = d, e, f
     183team3 = g, h, i
     184departmentA = team1, team2
     187Permission groups are not supported either, so you cannot do the following:
     190permission_level_1 = WIKI_VIEW, TICKET_VIEW
     191permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     193@team1 = permission_level_1
     194@team2 = permission_level_2
     195@team3 = permission_level_2, TICKET_CREATE
     198=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
     200At the time of this writing, the old granular 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's point of view, this makes little if any difference.
     202That kind of granular permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
     203More 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.
     208* = r
     211harry = rw
     212sally = r
     215harry =
     218 * '''/''' = ''Everyone has read access by default''
     219 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
     220 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
     222==== Trac Configuration ====
     224To activate granular permissions you __must__ specify the {{{authz_file}}} option in the `[svn]` section of trac.ini. If this option is set to null or not specified, the permissions will not be used.
     228authz_file = /path/to/svnaccessfile
     231If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     234authz_module_name = modulename
     237where ''modulename'' refers to the same repository indicated by the `<name>.dir` entry in the `[repositories]` section. As an example, if the `somemodule.dir` entry in the `[repositories]` section is `/srv/active/svn/somemodule`, that would yield the following:
     239{{{ #!ini
     241authz_file = /path/to/svnaccessfile
     242authz_module_name = somemodule
     245somemodule.dir = /srv/active/svn/somemodule
     248where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[somemodule:/some/path]}}}.
     250'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     252As 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.
     256permission_policies = AuthzSourcePolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     259==== Subversion Configuration ====
     261The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
     263<Location /repos>
     264  DAV svn
     265  SVNParentPath /usr/local/svn
     267  # our access control policy
     268  AuthzSVNAccessFile /path/to/svnaccessfile
     272For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess].
     274=== ReadonlyWikiPolicy
     276Since 1.1.2, the read-only attribute of wiki pages is enabled and enforced when `ReadonlyWikiPolicy` is in the list of active permission policies. The default for new Trac installations in 1.1.2 and later is:
     279permission_policies = ReadonlyWikiPolicy,
     280 DefaultPermissionPolicy,
     281 LegacyAttachmentPolicy
     284When upgrading from earlier versions of Trac, `ReadonlyWikiPolicy` will be appended to the list of `permission_policies` when upgrading the environment, provided that `permission_policies` has the default value. If any non-default `permission_polices` are active, `ReadonlyWikiPolicy` **will need to be manually added** to the list. A message will be echoed to the console when upgrading the environment, indicating if any action needs to be taken.
     286**!ReadonlyWikiPolicy must be listed //before// !DefaultPermissionPolicy**. The latter returns `True` to allow modify, delete or rename actions when the user has the respective `WIKI_*` permission, without consideration for the read-only attribute.
     288The `ReadonlyWikiPolicy` returns `False` to deny modify, delete and rename actions on wiki pages when the page has the read-only attribute set and the user does not have `WIKI_ADMIN`, regardless of `WIKI_MODIFY`, `WIKI_DELETE` and `WIKI_RENAME` permissions. It returns `None` for all other cases.
     290When active, the [#AuthzPolicy] should therefore come before `ReadonlyWikiPolicy`, allowing it to grant or deny the actions on individual resources, which is the usual ordering for `AuthzPolicy` in the `permission_policies` list.
     293permission_policies = AuthzPolicy,
     294 ReadonlyWikiPolicy,
     295 DefaultPermissionPolicy,
     296 LegacyAttachmentPolicy
     299The placement of [#AuthzSourcePolicy] relative to `ReadonlyWikiPolicy` does not matter since they don't perform checks on the same realms.
     301For all other permission policies, the user will need to decide the proper ordering. Generally, if the permission policy should be capable of overriding the check performed by `ReadonlyWikiPolicy`, it should come before `ReadonlyWikiPolicy` in the list. If the `ReadonlyWikiPolicy` should override the check performed by another permission policy, as is the case for `DefaultPermissionPolicy`, then `ReadonlyWikiPolicy` should come first.
     303== Debugging permissions
     304In trac.ini set:
     307log_file = trac.log
     308log_level = DEBUG
     309log_type = file
     312Display the trac.log to understand what checks are being performed:
     314tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
     317See the sourced documentation of the plugin for more info.
     320See also: TracPermissions,
     321[ TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.