Changes between Initial Version and Version 1 of TracFineGrainedPermissions


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Timestamp:
2013-10-03 14:14:25 (6 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==== Configuration ==== 
     32* Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj] (still needed for 0.12). 
     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==== Usage Notes ==== 
     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. `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. 
     61 
     62NOTE: Only if the return value is `None` will the ''next'' permission policy be consulted. 
     63If none of the policies explicitly grants the permission, the final result will be `False`  
     64(i.e. permission denied). 
     65 
     66The `authzpolicy.conf` file is a `.ini` style configuration file: 
     67{{{ 
     68[wiki:PrivatePage@*] 
     69john = WIKI_VIEW, !WIKI_MODIFY 
     70jack = WIKI_VIEW 
     71* = 
     72}}} 
     73* Each section of the config is a glob pattern used to match against a Trac resource 
     74  descriptor. These descriptors are in the form: 
     75{{{ 
     76<realm>:<id>@<version>[/<realm>:<id>@<version> ...] 
     77}}} 
     78  Resources are ordered left to right, from parent to child. If any 
     79  component is inapplicable, `*` is substituted. If the version pattern is 
     80  not specified explicitely, all versions (`@*`) is added implicitly 
     81 
     82  Example: Match the WikiStart page 
     83{{{ 
     84[wiki:*] 
     85[wiki:WikiStart*] 
     86[wiki:WikiStart@*] 
     87[wiki:WikiStart] 
     88}}} 
     89 
     90  Example: Match the attachment `wiki:WikiStart@117/attachment/FOO.JPG@*` 
     91  on WikiStart 
     92{{{ 
     93[wiki:*] 
     94[wiki:WikiStart*] 
     95[wiki:WikiStart@*] 
     96[wiki:WikiStart@*/attachment/*] 
     97[wiki:WikiStart@117/attachment/FOO.JPG] 
     98}}} 
     99 
     100* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of 
     101  appearance in the configuration file. '''ORDER IS CRITICAL'''. 
     102 
     103* Once a section matches, the current username is matched against the keys  
     104  (usernames) of the section, '''IN ORDER'''.  
     105  * If a key (username) is prefixed with a `@`, it is treated as a group.  
     106  * If a value (permission) is prefixed with a `!`, the permission is 
     107    denied rather than granted. 
     108 
     109  The username will match any of 'anonymous', 
     110  'authenticated', <username> or '*', using normal Trac permission rules. 
     111 
     112For example, if the `authz_file` contains: 
     113{{{ 
     114[wiki:WikiStart@*] 
     115* = WIKI_VIEW 
     116 
     117[wiki:PrivatePage@*] 
     118john = WIKI_VIEW 
     119* = !WIKI_VIEW 
     120}}} 
     121and the default permissions are set like this: 
     122{{{ 
     123john           WIKI_VIEW 
     124jack           WIKI_VIEW 
     125# anonymous has no WIKI_VIEW 
     126}}} 
     127 
     128Then:  
     129  * All versions of WikiStart will be viewable by everybody (including anonymous) 
     130  * !PrivatePage will be viewable only by john 
     131  * other pages will be viewable only by john and jack 
     132 
     133Groups: 
     134{{{ 
     135[groups] 
     136admins = john, jack 
     137devs = alice, bob 
     138 
     139[wiki:Dev@*] 
     140@admins = TRAC_ADMIN 
     141@devs = WIKI_VIEW 
     142* = 
     143 
     144[*] 
     145@admins = TRAC_ADMIN 
     146* = 
     147}}} 
     148 
     149Then: 
     150- everything is blocked (whitelist approach), but 
     151- admins get all TRAC_ADMIN everywhere and 
     152- devs can view wiki pages. 
     153 
     154Some repository examples (Browse Source specific): 
     155{{{ 
     156# A single repository: 
     157[repository:test_repo@*] 
     158john = BROWSER_VIEW, FILE_VIEW 
     159# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo 
     160 
     161# All repositories: 
     162[repository:*@*] 
     163jack = BROWSER_VIEW, FILE_VIEW 
     164# John has BROWSER_VIEW and FILE_VIEW for all repositories 
     165}}} 
     166 
     167Very fine grain repository access: 
     168{{{ 
     169# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only 
     170[repository:test_repo@*/source:trunk/src/some/location/*@*] 
     171john = BROWSER_VIEW, FILE_VIEW 
     172 
     173 
     174# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only 
     175[repository:test_repo@*/source:trunk/src/some/location/*@1] 
     176john = BROWSER_VIEW, FILE_VIEW 
     177 
     178 
     179# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only  
     180[repository:test_repo@*/source:trunk/src/some/location/somefile@*] 
     181john = BROWSER_VIEW, FILE_VIEW 
     182 
     183 
     184# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only 
     185[repository:test_repo@*/source:trunk/src/some/location/somefile@1] 
     186john = BROWSER_VIEW, FILE_VIEW 
     187}}} 
     188 
     189Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list. 
     190 
     191 
     192=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy 
     193 
     194At 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. 
     195 
     196That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.  
     197More 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. 
     198 
     199Example: 
     200{{{ 
     201[/] 
     202* = r 
     203 
     204[/branches/calc/bug-142] 
     205harry = rw 
     206sally = r 
     207 
     208[/branches/calc/bug-142/secret] 
     209harry = 
     210}}} 
     211 
     212 * '''/''' = ''Everyone has read access by default'' 
     213 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only'' 
     214 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)'' 
     215 
     216==== Trac Configuration ==== 
     217 
     218To 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. 
     219 
     220{{{ 
     221[trac] 
     222authz_file = /path/to/svnaccessfile 
     223}}} 
     224 
     225If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add  
     226 
     227{{{ 
     228authz_module_name = modulename 
     229}}} 
     230 
     231where ''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: 
     232 
     233{{{  
     234[trac] 
     235authz_file = /path/to/svnaccessfile 
     236authz_module_name = blahblah 
     237... 
     238repository_dir = /srv/active/svn/blahblah  
     239}}} 
     240 
     241where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}. 
     242 
     243'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.  
     244 
     245As 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. 
     246 
     247{{{  
     248[trac] 
     249permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy 
     250}}} 
     251 
     252==== Subversion Configuration ==== 
     253 
     254The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this: 
     255{{{ 
     256<Location /repos> 
     257  DAV svn 
     258  SVNParentPath /usr/local/svn 
     259 
     260  # our access control policy 
     261  AuthzSVNAccessFile /path/to/svnaccessfile 
     262</Location> 
     263}}} 
     264 
     265For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess] 
     266 
     267== Debugging permissions 
     268In trac.ini set: 
     269{{{ 
     270[logging] 
     271log_file = trac.log 
     272log_level = DEBUG 
     273log_type = file 
     274}}} 
     275 
     276And watch: 
     277{{{ 
     278tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]' 
     279}}} 
     280 
     281to understand what checks are being performed. See the sourced documentation of the plugin for more info. 
     282 
     283 
     284---- 
     285See also: TracPermissions, 
     286[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.