Changes between Initial Version and Version 1 of TracFineGrainedPermissions


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Timestamp:
03/14/15 20:29:38 (6 months ago)
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trac
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  • TracFineGrainedPermissions

    v1 v1  
     1[[PageOutline(2-5, Contents, floated)]]
     2= Fine grained permissions =
     3
     4Before Trac 0.11, it was only possible to define fine-grained permissions checks on the repository browser sub-system.
     5
     6Since 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.
     7
     8Note 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.
     9
     10
     11== Permission Policies ==
     12
     13A great diversity of permission policies can be implemented, and Trac comes with a few examples.
     14
     15Which policies are currently active is determined by a configuration setting in TracIni:
     16e.g.
     17{{{
     18[trac]
     19permission_policies = ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     20}}}
     21This 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.
     22
     23Among the possible optional choices, there is [#AuthzPolicy], a very generic permission policy, based on an Authz-style system. See
     24[trac:source:branches/0.12-stable/tracopt/perm/authz_policy.py authz_policy.py] for details.
     25
     26Another 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.
     27
     28See also [trac:source:branches/0.12-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
     29
     30
     31=== !AuthzPolicy ===
     32==== Configuration ====
     33* Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj] (still needed for 0.12 and later).
     34* Copy [browser:/trunk/tracopt/perm/authz_policy.py /tracopt/perm/authz_policy.py] to your environment's plugins directory (only for Trac 0.11).
     35* Put a [http://swapoff.org/files/authzpolicy.conf 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.
     36* Update your `trac.ini`:
     37  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section
     38{{{
     39[trac]
     40...
     41permission_policies = AuthzPolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     42}}}
     43  1. add a new `[authz_policy]` section
     44{{{
     45[authz_policy]
     46authz_file = /some/trac/env/conf/authzpolicy.conf
     47}}}
     48  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section
     49{{{
     50[components]
     51...
     52# Trac 0.12
     53tracopt.perm.authz_policy.* = enabled
     54# for Trac 0.11 use this
     55#authz_policy.* = enabled
     56}}}
     57
     58
     59==== Usage Notes ====
     60Note that the order in which permission policies are specified is quite critical,
     61as policies will be examined in the sequence provided.
     62
     63A 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.
     64
     65NOTE: Only if the return value is `None` will the ''next'' permission policy be consulted.
     66If none of the policies explicitly grants the permission, the final result will be `False`
     67(i.e. permission denied).
     68
     69The `authzpolicy.conf` file is a `.ini` style configuration file:
     70{{{
     71[wiki:PrivatePage@*]
     72john = WIKI_VIEW, !WIKI_MODIFY
     73jack = WIKI_VIEW
     74* =
     75}}}
     76* Each section of the config is a glob pattern used to match against a Trac resource
     77  descriptor. These descriptors are in the form:
     78{{{
     79<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
     80}}}
     81  Resources are ordered left to right, from parent to child. If any
     82  component is inapplicable, `*` is substituted. If the version pattern is
     83  not specified explicitely, all versions (`@*`) is added implicitly
     84
     85  Example: Match the WikiStart page
     86{{{
     87[wiki:*]
     88[wiki:WikiStart*]
     89[wiki:WikiStart@*]
     90[wiki:WikiStart]
     91}}}
     92
     93  Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*`
     94  on WikiStart
     95{{{
     96[wiki:*]
     97[wiki:WikiStart*]
     98[wiki:WikiStart@*]
     99[wiki:WikiStart@*/attachment:*]
     100[wiki:WikiStart@117/attachment:FOO.JPG]
     101}}}
     102
     103* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of
     104  appearance in the configuration file. '''ORDER IS CRITICAL'''.
     105
     106* Once a section matches, the current username is matched against the keys
     107  (usernames) of the section, '''IN ORDER'''.
     108  * If a key (username) is prefixed with a `@`, it is treated as a group.
     109  * If a value (permission) is prefixed with a `!`, the permission is
     110    denied rather than granted.
     111
     112  The 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 ||
     113
     114For example, if the `authz_file` contains:
     115{{{
     116[wiki:WikiStart@*]
     117* = WIKI_VIEW
     118
     119[wiki:PrivatePage@*]
     120john = WIKI_VIEW
     121* = !WIKI_VIEW
     122}}}
     123and the default permissions are set like this:
     124{{{
     125john           WIKI_VIEW
     126jack           WIKI_VIEW
     127# anonymous has no WIKI_VIEW
     128}}}
     129
     130Then:
     131  * All versions of WikiStart will be viewable by everybody (including anonymous)
     132  * !PrivatePage will be viewable only by john
     133  * other pages will be viewable only by john and jack
     134
     135Groups:
     136{{{
     137[groups]
     138admins = john, jack
     139devs = alice, bob
     140
     141[wiki:Dev@*]
     142@admins = TRAC_ADMIN
     143@devs = WIKI_VIEW
     144* =
     145
     146[*]
     147@admins = TRAC_ADMIN
     148* =
     149}}}
     150
     151Then:
     152- everything is blocked (whitelist approach), but
     153- admins get all TRAC_ADMIN everywhere and
     154- devs can view wiki pages.
     155
     156Some repository examples (Browse Source specific):
     157{{{
     158# A single repository:
     159[repository:test_repo@*]
     160john = BROWSER_VIEW, FILE_VIEW
     161# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
     162
     163# The default repository (requires Trac 1.0.2 or later):
     164[repository:@*]
     165john = BROWSER_VIEW, FILE_VIEW
     166# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
     167
     168# All repositories:
     169[repository:*@*]
     170jack = BROWSER_VIEW, FILE_VIEW
     171# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     172}}}
     173
     174Very fine grain repository access:
     175{{{
     176# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     177[repository:test_repo@*/source:trunk/src/some/location/*@*]
     178john = BROWSER_VIEW, FILE_VIEW
     179
     180
     181# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     182[repository:test_repo@*/source:trunk/src/some/location/*@1]
     183john = BROWSER_VIEW, FILE_VIEW
     184
     185
     186# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     187[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
     188john = BROWSER_VIEW, FILE_VIEW
     189
     190
     191# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     192[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
     193john = BROWSER_VIEW, FILE_VIEW
     194}}}
     195
     196Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     197
     198
     199==== Missing Features ====
     200Although 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 forgotten authz_policy.2.patch  part of [trac:ticket:6680 #6680]).
     201
     202You cannot do the following:
     203{{{
     204[groups]
     205team1 = a, b, c
     206team2 = d, e, f
     207team3 = g, h, i
     208departmentA = team1, team2
     209}}}
     210
     211Permission groups are not supported either. You cannot do the following:
     212{{{
     213[groups]
     214permission_level_1 = WIKI_VIEW, TICKET_VIEW
     215permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     216[*]
     217@team1 = permission_level_1
     218@team2 = permission_level_2
     219@team3 = permission_level_2, TICKET_CREATE
     220}}}
     221
     222=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
     223
     224At 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.
     225
     226That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
     227More information about this file format and about its usage in Subversion is available in the  [http://svnbook.red-bean.com/en/1.5/svn.serverconfig.pathbasedauthz.html Path-Based Authorization] section in the Server Configuration chapter of the svn book.
     228
     229Example:
     230{{{
     231[/]
     232* = r
     233
     234[/branches/calc/bug-142]
     235harry = rw
     236sally = r
     237
     238[/branches/calc/bug-142/secret]
     239harry =
     240}}}
     241
     242 * '''/''' = ''Everyone has read access by default''
     243 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
     244 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
     245
     246==== Trac Configuration ====
     247
     248To activate fine grained permissions you __must__ specify the {{{authz_file}}} option in the {{{[trac]}}} section of trac.ini. If this option is set to null or not specified the permissions will not be used.
     249
     250{{{
     251[trac]
     252authz_file = /path/to/svnaccessfile
     253}}}
     254
     255If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add
     256
     257{{{
     258authz_module_name = modulename
     259}}}
     260
     261where ''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 {{{/srv/active/svn/blahblah}}}, that would yield the following:
     262
     263{{{
     264[trac]
     265authz_file = /path/to/svnaccessfile
     266authz_module_name = blahblah
     267...
     268repository_dir = /srv/active/svn/blahblah
     269}}}
     270
     271where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}.
     272
     273'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     274
     275As 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.
     276
     277{{{
     278[trac]
     279permission_policies = AuthzSourcePolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     280}}}
     281
     282==== Subversion Configuration ====
     283
     284The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
     285{{{
     286<Location /repos>
     287  DAV svn
     288  SVNParentPath /usr/local/svn
     289
     290  # our access control policy
     291  AuthzSVNAccessFile /path/to/svnaccessfile
     292</Location>
     293}}}
     294
     295For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
     296
     297=== ReadonlyWikiPolicy
     298
     299Since 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:
     300{{{
     301[trac]
     302permission_policies = ReadonlyWikiPolicy,
     303 DefaultPermissionPolicy,
     304 LegacyAttachmentPolicy
     305}}}
     306
     307When 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.
     308
     309**!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.
     310
     311The `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.
     312
     313When 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.
     314{{{
     315[trac]
     316permission_policies = AuthzPolicy,
     317 ReadonlyWikiPolicy,
     318 DefaultPermissionPolicy,
     319 LegacyAttachmentPolicy
     320}}}
     321
     322The placement of [#AuthzSourcePolicy] relative to `ReadonlyWikiPolicy` does not matter since they don't perform checks on the same realms.
     323
     324For 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.
     325
     326== Debugging permissions
     327In trac.ini set:
     328{{{
     329[logging]
     330log_file = trac.log
     331log_level = DEBUG
     332log_type = file
     333}}}
     334
     335And watch:
     336{{{
     337tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
     338}}}
     339
     340to understand what checks are being performed. See the sourced documentation of the plugin for more info.
     341
     342----
     343See also: TracPermissions,
     344[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.