Changes between Initial Version and Version 1 of TracFineGrainedPermissions


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Timestamp:
Apr 21, 2020, 11:11:05 PM (7 months ago)
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trac
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  • 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 policies** to grant or deny any action on any Trac resource, or even specific versions of a resource.
     6
     7That mechanism is `AuthzPolicy`, an optional component in `tracopt.perm.authz_policy.*` which is not activated by default. It can be activated via the //Plugins// panel in the Trac administration module.
     8
     9See TracPermissions for a more general introduction to Trac permissions and permission policies.
     10
     11== Permission Policies
     12
     13A great diversity of permission policies can be implemented and Trac comes with a few examples.
     14
     15The active policies are determined by a [TracIni#trac-permission_policies-option configuration setting]:
     16
     17{{{#!ini
     18[trac]
     19permission_policies = DefaultWikiPolicy,
     20 DefaultTicketPolicy,
     21 DefaultPermissionPolicy,
     22 LegacyAttachmentPolicy
     23}}}
     24
     25* [#DefaultWikiPolicyandDefaultTicketPolicy DefaultWikiPolicy] controls readonly access to wiki pages.
     26* [#DefaultWikiPolicyandDefaultTicketPolicy DefaultTicketPolicy] provides elevated privileges in the ticket system for authenticated users.
     27* !DefaultPermissionPolicy checks for the traditional coarse-grained permissions described in TracPermissions.
     28* !LegacyAttachmentPolicy uses the coarse-grained permissions to check permissions on attachments.
     29
     30Among the optional choices, there is [#AuthzPolicy], a very generic permission policy, based on an Authz-style system. See
     31[trac:source:branches/1.4-stable/tracopt/perm/authz_policy.py authz_policy.py] for details.
     32
     33Another permission policy [#AuthzSourcePolicy], uses the [http://svnbook.red-bean.com/nightly/en/svn.serverconfig.pathbasedauthz.html path-based authorization] defined by Subversion to enforce permissions on the version control system.
     34
     35See also [trac:source:branches/1.4-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
     36
     37=== !AuthzPolicy
     38==== Configuration
     39* Put an empty conf file (`authzpolicy.conf`) in a secure location on the server, not readable by users other than the webuser. If the  file contains non-ASCII characters, the UTF-8 encoding should be used.
     40* Update your `trac.ini`:
     41  1. modify the [TracIni#trac-permission_policies-option permission_policies] option in the `[trac]` section:
     42{{{#!ini
     43[trac]
     44permission_policies = AuthzPolicy, DefaultWikiPolicy, DefaultTicketPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     45}}}
     46  1. add a new `[authz_policy]` section and point the `authz_file` option to the conf file:
     47{{{#!ini
     48[authz_policy]
     49authz_file = /some/trac/env/conf/authzpolicy.conf
     50}}}
     51  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     52{{{#!ini
     53[components]
     54tracopt.perm.authz_policy.* = enabled
     55}}}
     56
     57==== Usage Notes
     58
     59Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
     60
     61A 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.
     62
     63NOTE: 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.
     64
     65The `authzpolicy.conf` file is a `.ini` style configuration file:
     66{{{#!ini
     67[wiki:PrivatePage@*]
     68john = WIKI_VIEW, !WIKI_MODIFY
     69jack = WIKI_VIEW
     70* =
     71}}}
     72* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
     73{{{
     74<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
     75}}}
     76
     77Resources 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:
     78{{{#!ini
     79[wiki:*]
     80[wiki:WikiStart*]
     81[wiki:WikiStart@*]
     82[wiki:WikiStart]
     83}}}
     84
     85Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     86{{{#!ini
     87[wiki:*]
     88[wiki:WikiStart*]
     89[wiki:WikiStart@*]
     90[wiki:WikiStart@*/attachment:*]
     91[wiki:WikiStart@117/attachment:FOO.JPG]
     92}}}
     93
     94* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of appearance in the configuration file. '''ORDER IS CRITICAL'''.
     95
     96* Once a section matches, the current username is matched against the keys (usernames) of the section, '''IN ORDER'''.
     97  * If a key (username) is prefixed with a `@`, it is treated as a group.
     98  * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
     99
     100The username will match any of 'anonymous', 'authenticated', <username> or '*', using normal Trac permission rules.
     101
     102|| '''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:#5648] for details about this missing feature. ||
     103
     104For example, if the `authz_file` contains:
     105{{{#!ini
     106[wiki:WikiStart@*]
     107* = WIKI_VIEW
     108
     109[wiki:PrivatePage@*]
     110john = WIKI_VIEW
     111* = !WIKI_VIEW
     112}}}
     113and the default permissions are set like this:
     114{{{
     115john           WIKI_VIEW
     116jack           WIKI_VIEW
     117# anonymous has no WIKI_VIEW
     118}}}
     119
     120Then:
     121  * All versions of WikiStart will be viewable by everybody, including anonymous
     122  * !PrivatePage will be viewable only by john
     123  * other pages will be viewable only by john and jack
     124
     125Groups:
     126{{{#!ini
     127[groups]
     128admins = john, jack
     129devs = alice, bob
     130
     131[wiki:Dev@*]
     132@admins = TRAC_ADMIN
     133@devs = WIKI_VIEW
     134* =
     135
     136[*]
     137@admins = TRAC_ADMIN
     138* =
     139}}}
     140
     141Then:
     142- everything is blocked (whitelist approach), but
     143- admins get all TRAC_ADMIN everywhere and
     144- devs can view wiki pages.
     145
     146Some repository examples (Browse Source specific):
     147{{{#!ini
     148# A single repository:
     149[repository:test_repo@*]
     150john = BROWSER_VIEW, FILE_VIEW
     151# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
     152
     153# The default repository (requires Trac 1.0.2 or later):
     154[repository:@*]
     155john = BROWSER_VIEW, FILE_VIEW
     156# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
     157
     158# All repositories:
     159[repository:*@*]
     160jack = BROWSER_VIEW, FILE_VIEW
     161# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     162}}}
     163
     164Very granular repository access:
     165{{{#!ini
     166# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     167[repository:test_repo@*/source:trunk/src/some/location/*@*]
     168john = BROWSER_VIEW, FILE_VIEW
     169
     170# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     171[repository:test_repo@*/source:trunk/src/some/location/*@1]
     172john = BROWSER_VIEW, FILE_VIEW
     173
     174# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     175[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
     176john = BROWSER_VIEW, FILE_VIEW
     177
     178# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     179[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
     180john = BROWSER_VIEW, FILE_VIEW
     181}}}
     182
     183Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     184
     185==== Missing Features
     186Although possible with the !DefaultPermissionPolicy handling (see Admin panel), fine-grained permissions still miss those grouping features (see [trac:#9573], [trac:#5648]). Patches are partially available, see authz_policy.2.patch, part of [trac:ticket:6680 #6680].
     187
     188You cannot do the following:
     189{{{#!ini
     190[groups]
     191team1 = a, b, c
     192team2 = d, e, f
     193team3 = g, h, i
     194departmentA = team1, team2
     195}}}
     196
     197Permission groups are not supported either, so you cannot do the following:
     198{{{#!ini
     199[groups]
     200permission_level_1 = WIKI_VIEW, TICKET_VIEW
     201permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     202[*]
     203@team1 = permission_level_1
     204@team2 = permission_level_2
     205@team3 = permission_level_2, TICKET_CREATE
     206}}}
     207
     208=== !AuthzSourcePolicy  (`mod_authz_svn`-like permission policy) #AuthzSourcePolicy
     209
     210`AuthzSourcePolicy` can be used for restricting access to the repository. Granular permission control needs a definition file, which is the one used by Subversion's `mod_authz_svn`.
     211More information about this file format and about its usage in Subversion is available in the [http://svnbook.red-bean.com/en/1.7/svn.serverconfig.pathbasedauthz.html Path-Based Authorization] section in the Server Configuration chapter of the svn book.
     212
     213Example:
     214{{{#!ini
     215[/]
     216* = r
     217
     218[/branches/calc/bug-142]
     219harry = rw
     220sally = r
     221
     222[/branches/calc/bug-142/secret]
     223harry =
     224}}}
     225
     226 * '''/''' = ''Everyone has read access by default''
     227 * '''/branches/calc/bug-142''' = ''harry has read/write access, sally read only''
     228 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
     229
     230==== Trac Configuration
     231
     232To 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.
     233
     234{{{#!ini
     235[svn]
     236authz_file = /path/to/svnaccessfile
     237}}}
     238
     239If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     240
     241{{{#!ini
     242authz_module_name = modulename
     243}}}
     244
     245where ''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:
     246
     247{{{ #!ini
     248[svn]
     249authz_file = /path/to/svnaccessfile
     250authz_module_name = somemodule
     251...
     252[repositories]
     253somemodule.dir = /srv/active/svn/somemodule
     254}}}
     255
     256where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[somemodule:/some/path]}}}.
     257
     258'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     259
     260Make sure you have ''!AuthzSourcePolicy'' included in the permission_policies list in trac.ini, otherwise the authz permissions file will be ignored.
     261
     262{{{#!ini
     263[trac]
     264permission_policies = AuthzSourcePolicy, DefaultWikiPolicy, DefaultTicketPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     265}}}
     266
     267==== Subversion Configuration
     268
     269The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
     270{{{#!apache
     271<Location /repos>
     272  DAV svn
     273  SVNParentPath /usr/local/svn
     274
     275  # our access control policy
     276  AuthzSVNAccessFile /path/to/svnaccessfile
     277</Location>
     278}}}
     279
     280For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess].
     281
     282=== !DefaultWikiPolicy and !DefaultTicketPolicy
     283
     284Since 1.1.2, the read-only attribute of wiki pages is enabled and enforced when `DefaultWikiPolicy` is in the list of active permission policies (`DefaultWikiPolicy` was named `ReadonlyWikiPolicy` from Trac 1.1.2 to 1.3.1). The default for new Trac installations in 1.3.2 and later is:
     285{{{#!ini
     286[trac]
     287permission_policies = DefaultWikiPolicy,
     288 DefaultTicketPolicy,
     289 DefaultPermissionPolicy,
     290 LegacyAttachmentPolicy
     291}}}
     292
     293`DefaultWikiPolicy` 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, which causes the next permission policy in the list to be consulted.
     294
     295Since 1.3.2 `DefaultTicketPolicy` implements the following behaviors:
     296* Authenticated user can edit their own comments.
     297* Authenticated user with `TICKET_APPEND` or `TICKET_CHGPROP` can modify the description of a ticket they reported.
     298* User with `MILESTONE_VIEW` can change  the ticket milestone.
     299
     300The wiki- and ticket-specific behaviors are implemented in permission policies so they can be easily replaced in case other behavior is desired.
     301
     302When upgrading from earlier versions of Trac, `DefaultWikiPolicy, DefaultTicketPolicy` will be appended to the list of `permission_policies` when upgrading the environment, provided that `permission_policies` has the default value (`ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy` if upgrading from Trac 1.1.2 or later). If any non-default `permission_polices` are active, `DefaultWikiPolicy, DefaultTicketPolicy` **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.
     303
     304**!DefaultWikiPolicy and !DefaultTicketPolicy 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. Similarly, some of the behaviors implemented in `DefaultTicketPolicy` won't be considered if `DefaultPermissionPolicy` is executed first.
     305
     306When active, the [#AuthzPolicy] should therefore come before `DefaultWikiPolicy, DefaultTicketPolicy`, allowing it to grant or deny the actions on individual resources, which is the usual ordering for `AuthzPolicy` in the `permission_policies` list.
     307{{{#!ini
     308[trac]
     309permission_policies = AuthzPolicy,
     310 DefaultWikiPolicy,
     311 DefaultTicketPolicy,
     312 DefaultPermissionPolicy,
     313 LegacyAttachmentPolicy
     314}}}
     315
     316The placement of [#AuthzSourcePolicy] relative to `DefaultWikiPolicy, DefaultTicketPolicy` does not matter since they don't perform checks on the same realms.
     317
     318For all other permission policies, the user will need to decide the proper ordering. Generally, if the permission policy should be capable of overriding the checks performed by `DefaultWikiPolicy` or `DefaultTicketPolicy`, it should come before the policy it overrides. If `DefaultWikiPolicy` or `DefaultTicketPolicy` should override the check performed by another permission policy, as is the case for those policies relative to `DefaultPermissionPolicy`, then the overriding policy should come first.
     319
     320== Debugging permissions
     321In trac.ini set:
     322{{{#!ini
     323[logging]
     324log_file = trac.log
     325log_level = DEBUG
     326log_type = file
     327}}}
     328
     329Display the trac.log to understand what checks are being performed:
     330{{{#!sh
     331tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
     332}}}
     333
     334See the sourced documentation of the plugin for more info.
     335
     336----
     337See also: TracPermissions,
     338[http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin FineGrainedPageAuthzEditorPlugin] for a simple editor.