Changes between Initial Version and Version 1 of TracFineGrainedPermissions


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Timestamp:
08/02/11 11:44:45 (7 years ago)
Author:
trac
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  • TracFineGrainedPermissions

    v1 v1  
     1= Fine grained permissions = 
     2 
     3Before Trac 0.11, it was only possible to define fine-grained permissions checks on the repository browser sub-system. 
     4 
     5Since 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. 
     6 
     7Note 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. 
     8 
     9 
     10== Permission Policies == 
     11 
     12A great diversity of permission policies can be implemented, and Trac comes with a few examples.  
     13 
     14Which policies are currently active is determined by a configuration setting in TracIni: 
     15e.g. 
     16{{{ 
     17[trac] 
     18permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy 
     19}}} 
     20This 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. 
     21 
     22Among the possible optional choices, there is [#AuthzPolicy], a very generic permission policy, based on an Authz-style system. See 
     23[trac:source:branches/0.12-stable/tracopt/perm/authz_policy.py authz_policy.py] for details.  
     24 
     25Another 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. 
     26 
     27See also [trac:source:branches/0.12-stable/sample-plugins/permissions sample-plugins/permissions] for more examples. 
     28 
     29 
     30=== !AuthzPolicy ===  
     31 
     32 - Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj] (required). 
     33 - Copy authz_policy.py into your plugins directory. 
     34 - 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. 
     35 - Update your `trac.ini`: 
     36   1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section 
     37{{{ 
     38[trac] 
     39... 
     40permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy 
     41}}} 
     42   2. add a new `[authz_policy]` section 
     43{{{ 
     44[authz_policy] 
     45authz_file = /some/trac/env/conf/authzpolicy.conf 
     46}}} 
     47   3. enable the single file plugin 
     48{{{ 
     49[components] 
     50... 
     51# Trac 0.12 
     52tracopt.perm.authz_policy.* = enabled 
     53# for Trac 0.11 use this 
     54#authz_policy.* = enabled  
     55}}} 
     56 
     57Note that the order in which permission policies are specified is quite critical,  
     58as policies will be examined in the sequence provided. 
     59 
     60A policy will return either `True`, `False` or `None` for a given permission check. 
     61Only if the return value is `None` will the ''next'' permission policy be consulted. 
     62If no policy explicitly grants the permission, the final result will be `False`  
     63(i.e. no permission). 
     64 
     65For example, if the `authz_file` contains: 
     66{{{ 
     67[wiki:WikiStart@*] 
     68* = WIKI_VIEW 
     69 
     70[wiki:PrivatePage@*] 
     71john = WIKI_VIEW 
     72* = 
     73}}} 
     74and the default permissions are set like this: 
     75{{{ 
     76john           WIKI_VIEW 
     77jack           WIKI_VIEW 
     78# anonymous has no WIKI_VIEW 
     79}}} 
     80 
     81Then:  
     82 - All versions of WikiStart will be viewable by everybody (including anonymous) 
     83 - !PrivatePage will be viewable only by john 
     84 - other pages will be viewable only by john and jack 
     85 
     86 
     87=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy 
     88 
     89At 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. 
     90 
     91That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.  
     92More 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. 
     93 
     94Example: 
     95{{{ 
     96[/] 
     97* = r 
     98 
     99[/branches/calc/bug-142] 
     100harry = rw 
     101sally = r 
     102 
     103[/branches/calc/bug-142/secret] 
     104harry = 
     105}}} 
     106 
     107 * '''/''' = ''Everyone has read access by default'' 
     108 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only'' 
     109 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)'' 
     110 
     111==== Trac Configuration ==== 
     112 
     113To 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. 
     114 
     115{{{ 
     116[trac] 
     117authz_file = /path/to/svnaccessfile 
     118}}} 
     119 
     120If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add  
     121 
     122{{{ 
     123authz_module_name = modulename 
     124}}} 
     125 
     126where ''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: 
     127 
     128{{{  
     129[trac] 
     130authz_file = /path/to/svnaccessfile 
     131authz_module_name = blahblah 
     132... 
     133repository_dir = /srv/active/svn/blahblah  
     134}}} 
     135 
     136where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}. 
     137 
     138'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.  
     139 
     140As 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. 
     141 
     142{{{  
     143[trac] 
     144permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy 
     145}}} 
     146 
     147==== Subversion Configuration ==== 
     148 
     149The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this: 
     150{{{ 
     151<Location /repos> 
     152  DAV svn 
     153  SVNParentPath /usr/local/svn 
     154 
     155  # our access control policy 
     156  AuthzSVNAccessFile /path/to/svnaccessfile 
     157</Location> 
     158}}} 
     159 
     160For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess] 
     161 
     162== Debugging permissions 
     163In trac.ini set: 
     164{{{ 
     165[logging] 
     166log_file = trac.log 
     167log_level = DEBUG 
     168log_type = file 
     169}}} 
     170 
     171And watch: 
     172{{{ 
     173tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]' 
     174}}} 
     175 
     176to understand what checks are being performed. See the sourced documentation of the plugin for more info. 
     177 
     178 
     179---- 
     180See also: TracPermissions, 
     181[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.