Changes between Initial Version and Version 1 of TracFineGrainedPermissions


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Timestamp:
Jun 26, 2013, 4:32:13 PM (6 years 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 = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     20}}}
     21This 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.
     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).
     34* Copy authz_policy.py into your 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, 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# All repositories:
     164[repository:*@*]
     165jack = BROWSER_VIEW, FILE_VIEW
     166# John has BROWSER_VIEW and FILE_VIEW for all repositories
     167}}}
     168
     169Very fine grain repository access:
     170{{{
     171# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     172[repository:test_repo@*/source:trunk/src/some/location/*@*]
     173john = BROWSER_VIEW, FILE_VIEW
     174
     175
     176# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     177[repository:test_repo@*/source:trunk/src/some/location/*@1]
     178john = BROWSER_VIEW, FILE_VIEW
     179
     180
     181# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     182[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
     183john = BROWSER_VIEW, FILE_VIEW
     184
     185
     186# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     187[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
     188john = BROWSER_VIEW, FILE_VIEW
     189}}}
     190
     191Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     192
     193
     194==== Missing Features ====
     195Although 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]).
     196
     197You cannot do the following:
     198{{{
     199[groups]
     200team1 = a, b, c
     201team2 = d, e, f
     202team3 = g, h, i
     203departmentA = team1, team2
     204}}}
     205
     206Permission groups are not supported either. You cannot do the following:
     207{{{
     208[groups]
     209permission_level_1 = WIKI_VIEW, TICKET_VIEW
     210permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     211[*]
     212@team1 = permission_level_1
     213@team2 = permission_level_2
     214@team3 = permission_level_2, TICKET_CREATE
     215}}}
     216
     217=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
     218
     219At 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.
     220
     221That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
     222More 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.
     223
     224Example:
     225{{{
     226[/]
     227* = r
     228
     229[/branches/calc/bug-142]
     230harry = rw
     231sally = r
     232
     233[/branches/calc/bug-142/secret]
     234harry =
     235}}}
     236
     237 * '''/''' = ''Everyone has read access by default''
     238 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
     239 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
     240
     241==== Trac Configuration ====
     242
     243To 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.
     244
     245{{{
     246[trac]
     247authz_file = /path/to/svnaccessfile
     248}}}
     249
     250If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add
     251
     252{{{
     253authz_module_name = modulename
     254}}}
     255
     256where ''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:
     257
     258{{{
     259[trac]
     260authz_file = /path/to/svnaccessfile
     261authz_module_name = blahblah
     262...
     263repository_dir = /srv/active/svn/blahblah
     264}}}
     265
     266where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}.
     267
     268'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     269
     270As 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.
     271
     272{{{
     273[trac]
     274permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     275}}}
     276
     277==== Subversion Configuration ====
     278
     279The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
     280{{{
     281<Location /repos>
     282  DAV svn
     283  SVNParentPath /usr/local/svn
     284
     285  # our access control policy
     286  AuthzSVNAccessFile /path/to/svnaccessfile
     287</Location>
     288}}}
     289
     290For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
     291
     292== Debugging permissions
     293In trac.ini set:
     294{{{
     295[logging]
     296log_file = trac.log
     297log_level = DEBUG
     298log_type = file
     299}}}
     300
     301And watch:
     302{{{
     303tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
     304}}}
     305
     306to understand what checks are being performed. See the sourced documentation of the plugin for more info.
     307
     308
     309----
     310See also: TracPermissions,
     311[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.