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Changes between Initial Version and Version 1 of 1.0/TracFineGrainedPermissions


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Timestamp:
Nov 13, 2016, 12:25:27 AM (3 years ago)
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trac
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  • 1.0/TracFineGrainedPermissions

    v1 v1  
     1= Fine grained permissions =
     2[[PageOutline(2-5, Contents, floated)]]
     3[[TracGuideToc]]
     4
     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.
     6
     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.
     8
     9== Permission Policies ==
     10
     11A great diversity of permission policies can be implemented and Trac comes with a few examples.
     12
     13Which policies are currently active is determined by a configuration setting in TracIni:
     14
     15{{{#!ini
     16[trac]
     17permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     18}}}
     19This 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.
     20
     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/authz_policy.py authz_policy.py] for details.
     23
     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.
     25
     26See also [trac:source:branches/1.0-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
     27
     28=== !AuthzPolicy ===
     29==== Configuration ====
     30* Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj].
     31* 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.
     32* Update your `trac.ini`:
     33  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section:
     34{{{#!ini
     35[trac]
     36...
     37permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     38}}}
     39  1. add a new `[authz_policy]` section:
     40{{{#!ini
     41[authz_policy]
     42authz_file = /some/trac/env/conf/authzpolicy.conf
     43}}}
     44  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     45{{{#!ini
     46[components]
     47tracopt.perm.authz_policy.* = enabled
     48}}}
     49
     50==== Usage Notes ====
     51
     52Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
     53
     54A 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.
     55
     56NOTE: 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.
     57
     58The `authzpolicy.conf` file is a `.ini` style configuration file:
     59{{{#!ini
     60[wiki:PrivatePage@*]
     61john = WIKI_VIEW, !WIKI_MODIFY
     62jack = WIKI_VIEW
     63* =
     64}}}
     65* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
     66{{{
     67<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
     68}}}
     69
     70Resources 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:
     71{{{#!ini
     72[wiki:*]
     73[wiki:WikiStart*]
     74[wiki:WikiStart@*]
     75[wiki:WikiStart]
     76}}}
     77
     78Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     79{{{#!ini
     80[wiki:*]
     81[wiki:WikiStart*]
     82[wiki:WikiStart@*]
     83[wiki:WikiStart@*/attachment:*]
     84[wiki:WikiStart@117/attachment:FOO.JPG]
     85}}}
     86
     87* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of appearance in the configuration file. '''ORDER IS CRITICAL'''.
     88
     89* Once a section matches, the current username is matched against the keys (usernames) of the section, '''IN ORDER'''.
     90  * If a key (username) is prefixed with a `@`, it is treated as a group.
     91  * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
     92
     93The 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. ||
     94
     95For example, if the `authz_file` contains:
     96{{{#!ini
     97[wiki:WikiStart@*]
     98* = WIKI_VIEW
     99
     100[wiki:PrivatePage@*]
     101john = WIKI_VIEW
     102* = !WIKI_VIEW
     103}}}
     104and the default permissions are set like this:
     105{{{
     106john           WIKI_VIEW
     107jack           WIKI_VIEW
     108# anonymous has no WIKI_VIEW
     109}}}
     110
     111Then:
     112  * All versions of WikiStart will be viewable by everybody, including anonymous
     113  * !PrivatePage will be viewable only by john
     114  * other pages will be viewable only by john and jack
     115
     116Groups:
     117{{{#!ini
     118[groups]
     119admins = john, jack
     120devs = alice, bob
     121
     122[wiki:Dev@*]
     123@admins = TRAC_ADMIN
     124@devs = WIKI_VIEW
     125* =
     126
     127[*]
     128@admins = TRAC_ADMIN
     129* =
     130}}}
     131
     132Then:
     133- everything is blocked (whitelist approach), but
     134- admins get all TRAC_ADMIN everywhere and
     135- devs can view wiki pages.
     136
     137Some repository examples (Browse Source specific):
     138{{{#!ini
     139# A single repository:
     140[repository:test_repo@*]
     141john = BROWSER_VIEW, FILE_VIEW
     142# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
     143
     144# The default repository (requires Trac 1.0.2 or later):
     145[repository:@*]
     146john = BROWSER_VIEW, FILE_VIEW
     147# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
     148
     149# All repositories:
     150[repository:*@*]
     151jack = BROWSER_VIEW, FILE_VIEW
     152# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     153}}}
     154
     155Very granular repository access:
     156{{{#!ini
     157# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     158[repository:test_repo@*/source:trunk/src/some/location/*@*]
     159john = BROWSER_VIEW, FILE_VIEW
     160
     161# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     162[repository:test_repo@*/source:trunk/src/some/location/*@1]
     163john = BROWSER_VIEW, FILE_VIEW
     164
     165# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     166[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
     167john = BROWSER_VIEW, FILE_VIEW
     168
     169# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     170[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
     171john = BROWSER_VIEW, FILE_VIEW
     172}}}
     173
     174Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     175
     176==== Missing Features ====
     177Although 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].
     178
     179You cannot do the following:
     180{{{#!ini
     181[groups]
     182team1 = a, b, c
     183team2 = d, e, f
     184team3 = g, h, i
     185departmentA = team1, team2
     186}}}
     187
     188Permission groups are not supported either, so you cannot do the following:
     189{{{#!ini
     190[groups]
     191permission_level_1 = WIKI_VIEW, TICKET_VIEW
     192permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     193[*]
     194@team1 = permission_level_1
     195@team2 = permission_level_2
     196@team3 = permission_level_2, TICKET_CREATE
     197}}}
     198
     199=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
     200
     201At 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.
     202
     203That kind of granular permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
     204More 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.
     205
     206Example:
     207{{{#!ini
     208[/]
     209* = r
     210
     211[/branches/calc/bug-142]
     212harry = rw
     213sally = r
     214
     215[/branches/calc/bug-142/secret]
     216harry =
     217}}}
     218
     219 * '''/''' = ''Everyone has read access by default''
     220 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
     221 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
     222
     223==== Trac Configuration ====
     224
     225To activate granular 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.
     226
     227{{{#!ini
     228[trac]
     229authz_file = /path/to/svnaccessfile
     230}}}
     231
     232If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     233
     234{{{#!ini
     235authz_module_name = modulename
     236}}}
     237
     238where ''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/somemodule}}}, that would yield the following:
     239
     240{{{ #!ini
     241[trac]
     242authz_file = /path/to/svnaccessfile
     243authz_module_name = somemodule
     244...
     245repository_dir = /srv/active/svn/somemodule
     246}}}
     247
     248where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[somemodule:/some/path]}}}.
     249
     250'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     251
     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.
     253
     254{{{#!ini
     255[trac]
     256permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     257}}}
     258
     259==== Subversion Configuration ====
     260
     261The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
     262{{{#!apache
     263<Location /repos>
     264  DAV svn
     265  SVNParentPath /usr/local/svn
     266
     267  # our access control policy
     268  AuthzSVNAccessFile /path/to/svnaccessfile
     269</Location>
     270}}}
     271
     272For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess].
     273
     274== Debugging permissions
     275In trac.ini set:
     276{{{#!ini
     277[logging]
     278log_file = trac.log
     279log_level = DEBUG
     280log_type = file
     281}}}
     282
     283Display the trac.log to understand what checks are being performed:
     284{{{#!sh
     285tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
     286}}}
     287
     288See the sourced documentation of the plugin for more info.
     289
     290----
     291See also: TracPermissions,
     292[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.