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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 = ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
18}}}
19This lists the [#ReadonlyWikiPolicy] which controls readonly access to wiki pages, 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* 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.
31* Update your `trac.ini`:
32  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section:
33{{{#!ini
34[trac]
35...
36permission_policies = AuthzPolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
37}}}
38  1. add a new `[authz_policy]` section:
39{{{#!ini
40[authz_policy]
41authz_file = /some/trac/env/conf/authzpolicy.conf
42}}}
43  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
44{{{#!ini
45[components]
46tracopt.perm.authz_policy.* = enabled
47}}}
48
49==== Usage Notes ====
50
51Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
52
53A 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.
54
55NOTE: 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.
56
57The `authzpolicy.conf` file is a `.ini` style configuration file:
58{{{#!ini
59[wiki:PrivatePage@*]
60john = WIKI_VIEW, !WIKI_MODIFY
61jack = WIKI_VIEW
62* =
63}}}
64* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
65{{{
66<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
67}}}
68
69Resources 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:
70{{{#!ini
71[wiki:*]
72[wiki:WikiStart*]
73[wiki:WikiStart@*]
74[wiki:WikiStart]
75}}}
76
77Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
78{{{#!ini
79[wiki:*]
80[wiki:WikiStart*]
81[wiki:WikiStart@*]
82[wiki:WikiStart@*/attachment:*]
83[wiki:WikiStart@117/attachment:FOO.JPG]
84}}}
85
86* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of appearance in the configuration file. '''ORDER IS CRITICAL'''.
87
88* Once a section matches, the current username is matched against the keys (usernames) of the section, '''IN ORDER'''.
89  * If a key (username) is prefixed with a `@`, it is treated as a group.
90  * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
91
92The 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. ||
93
94For example, if the `authz_file` contains:
95{{{#!ini
96[wiki:WikiStart@*]
97* = WIKI_VIEW
98
99[wiki:PrivatePage@*]
100john = WIKI_VIEW
101* = !WIKI_VIEW
102}}}
103and the default permissions are set like this:
104{{{
105john           WIKI_VIEW
106jack           WIKI_VIEW
107# anonymous has no WIKI_VIEW
108}}}
109
110Then:
111  * All versions of WikiStart will be viewable by everybody, including anonymous
112  * !PrivatePage will be viewable only by john
113  * other pages will be viewable only by john and jack
114
115Groups:
116{{{#!ini
117[groups]
118admins = john, jack
119devs = alice, bob
120
121[wiki:Dev@*]
122@admins = TRAC_ADMIN
123@devs = WIKI_VIEW
124* =
125
126[*]
127@admins = TRAC_ADMIN
128* =
129}}}
130
131Then:
132- everything is blocked (whitelist approach), but
133- admins get all TRAC_ADMIN everywhere and
134- devs can view wiki pages.
135
136Some repository examples (Browse Source specific):
137{{{#!ini
138# A single repository:
139[repository:test_repo@*]
140john = BROWSER_VIEW, FILE_VIEW
141# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
142
143# The default repository (requires Trac 1.0.2 or later):
144[repository:@*]
145john = BROWSER_VIEW, FILE_VIEW
146# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
147
148# All repositories:
149[repository:*@*]
150jack = BROWSER_VIEW, FILE_VIEW
151# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
152}}}
153
154Very granular repository access:
155{{{#!ini
156# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
157[repository:test_repo@*/source:trunk/src/some/location/*@*]
158john = BROWSER_VIEW, FILE_VIEW
159
160# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
161[repository:test_repo@*/source:trunk/src/some/location/*@1]
162john = BROWSER_VIEW, FILE_VIEW
163
164# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
165[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
166john = BROWSER_VIEW, FILE_VIEW
167
168# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
169[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
170john = BROWSER_VIEW, FILE_VIEW
171}}}
172
173Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
174
175==== Missing Features ====
176Although 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].
177
178You cannot do the following:
179{{{#!ini
180[groups]
181team1 = a, b, c
182team2 = d, e, f
183team3 = g, h, i
184departmentA = team1, team2
185}}}
186
187Permission groups are not supported either, so you cannot do the following:
188{{{#!ini
189[groups]
190permission_level_1 = WIKI_VIEW, TICKET_VIEW
191permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
192[*]
193@team1 = permission_level_1
194@team2 = permission_level_2
195@team3 = permission_level_2, TICKET_CREATE
196}}}
197
198=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
199
200At 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.
201
202That kind of granular permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
203More 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.
204
205Example:
206{{{#!ini
207[/]
208* = r
209
210[/branches/calc/bug-142]
211harry = rw
212sally = r
213
214[/branches/calc/bug-142/secret]
215harry =
216}}}
217
218 * '''/''' = ''Everyone has read access by default''
219 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
220 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
221
222==== Trac Configuration ====
223
224To activate granular permissions you __must__ specify the {{{authz_file}}} option in the `[svn]` section of trac.ini. If this option is set to null or not specified, the permissions will not be used.
225
226{{{#!ini
227[svn]
228authz_file = /path/to/svnaccessfile
229}}}
230
231If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
232
233{{{#!ini
234authz_module_name = modulename
235}}}
236
237where ''modulename'' refers to the same repository indicated by the `<name>.dir` entry in the `[repositories]` section. As an example, if the `somemodule.dir` entry in the `[repositories]` section is `/srv/active/svn/somemodule`, that would yield the following:
238
239{{{ #!ini
240[svn]
241authz_file = /path/to/svnaccessfile
242authz_module_name = somemodule
243...
244[repositories]
245somemodule.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, ReadonlyWikiPolicy, 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=== ReadonlyWikiPolicy
275
276Since 1.1.2, the read-only attribute of wiki pages is enabled and enforced when `ReadonlyWikiPolicy` is in the list of active permission policies. The default for new Trac installations in 1.1.2 and later is:
277{{{
278[trac]
279permission_policies = ReadonlyWikiPolicy,
280 DefaultPermissionPolicy,
281 LegacyAttachmentPolicy
282}}}
283
284When upgrading from earlier versions of Trac, `ReadonlyWikiPolicy` will be appended to the list of `permission_policies` when upgrading the environment, provided that `permission_policies` has the default value. If any non-default `permission_polices` are active, `ReadonlyWikiPolicy` **will need to be manually added** to the list. A message will be echoed to the console when upgrading the environment, indicating if any action needs to be taken.
285
286**!ReadonlyWikiPolicy must be listed //before// !DefaultPermissionPolicy**. The latter returns `True` to allow modify, delete or rename actions when the user has the respective `WIKI_*` permission, without consideration for the read-only attribute.
287
288The `ReadonlyWikiPolicy` returns `False` to deny modify, delete and rename actions on wiki pages when the page has the read-only attribute set and the user does not have `WIKI_ADMIN`, regardless of `WIKI_MODIFY`, `WIKI_DELETE` and `WIKI_RENAME` permissions. It returns `None` for all other cases.
289
290When active, the [#AuthzPolicy] should therefore come before `ReadonlyWikiPolicy`, allowing it to grant or deny the actions on individual resources, which is the usual ordering for `AuthzPolicy` in the `permission_policies` list.
291{{{
292[trac]
293permission_policies = AuthzPolicy,
294 ReadonlyWikiPolicy,
295 DefaultPermissionPolicy,
296 LegacyAttachmentPolicy
297}}}
298
299The placement of [#AuthzSourcePolicy] relative to `ReadonlyWikiPolicy` does not matter since they don't perform checks on the same realms.
300
301For all other permission policies, the user will need to decide the proper ordering. Generally, if the permission policy should be capable of overriding the check performed by `ReadonlyWikiPolicy`, it should come before `ReadonlyWikiPolicy` in the list. If the `ReadonlyWikiPolicy` should override the check performed by another permission policy, as is the case for `DefaultPermissionPolicy`, then `ReadonlyWikiPolicy` should come first.
302
303== Debugging permissions
304In trac.ini set:
305{{{#!ini
306[logging]
307log_file = trac.log
308log_level = DEBUG
309log_type = file
310}}}
311
312Display the trac.log to understand what checks are being performed:
313{{{#!sh
314tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
315}}}
316
317See the sourced documentation of the plugin for more info.
318
319----
320See also: TracPermissions,
321[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.
Note: See TracBrowser for help on using the repository browser.