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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.
Note: See TracBrowser for help on using the repository browser.