Changes between Version 2 and Version 3 of TracFineGrainedPermissions


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Timestamp:
25 Jan 2017, 21:56:44 (12 months ago)
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trac
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  • TracFineGrainedPermissions

    v2 v3  
    11= Fine grained permissions =
    2 
    3 Before Trac 0.11, it was only possible to define fine-grained permissions checks on the repository browser sub-system.
    4 
    5 Since 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 
    7 Note that for Trac 0.12, `authz_policy` has been integrated in trunk branch as `tracopt.perm.authz_policy.*`
     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.
    88
    99== Permission Policies ==
    1010
    11 === !AuthzPolicy ===
    12 
    13 An example policy based on an Authz-style system has been added. See
    14 [trac:source:branches/0.11-stable/sample-plugins/permissions/authz_policy.py authz_policy.py] for details (current version requires >= Python 2.4). (See also [trac:source:branches/0.11-stable/sample-plugins/permissions sample-plugins/permissions] for more samples.)
    15 
    16  - Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj] (required).
    17  - Copy authz_policy.py into your plugins directory.
    18  - 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.
    19  - Update your `trac.ini`:
    20    1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section
    21 {{{
     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
    2234[trac]
    2335...
    24 permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    25 }}}
    26    2. add a new `[authz_policy]` section
    27 {{{
     36permission_policies = AuthzPolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     37}}}
     38  1. add a new `[authz_policy]` section:
     39{{{#!ini
    2840[authz_policy]
    2941authz_file = /some/trac/env/conf/authzpolicy.conf
    3042}}}
    31    3. enable the single file plugin
     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:
    3265{{{
    33 [components]
    34 ...
    35 authz_policy.* = enabled
    36 }}}
    37 
    38 Note that the order in which permission policies are specified is quite critical,
    39 as policies will be examined in the sequence provided.
    40 
    41 A policy will return either `True`, `False` or `None` for a given permission check.
    42 Only if the return value is `None` will the ''next'' permission policy be consulted.
    43 If no policy explicitly grants the permission, the final result will be `False`
    44 (i.e. no permission).
     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. ||
    4593
    4694For example, if the `authz_file` contains:
    47 {{{
     95{{{#!ini
    4896[wiki:WikiStart@*]
    4997* = WIKI_VIEW
     
    5199[wiki:PrivatePage@*]
    52100john = WIKI_VIEW
    53 * =
     101* = !WIKI_VIEW
    54102}}}
    55103and the default permissions are set like this:
     
    61109
    62110Then:
    63  - All versions of WikiStart will be viewable by everybody (including anonymous)
    64  - !PrivatePage will be viewable only by john
    65  - other pages will be viewable only by john and jack
    66 
    67 
    68 === mod_authz_svn-like permission policy ===
    69 
    70 At the time of this writing, the old fine grained permissions system from Trac 0.10 and before used for restricting access to the repository has not yet been converted to a permission policy component, but from the user point of view, this makes little if no difference.
    71 
    72 That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
    73 More 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.
     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.
    74204
    75205Example:
    76 {{{
     206{{{#!ini
    77207[/]
    78208* = r
     
    92222==== Trac Configuration ====
    93223
    94 To 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.
    95 
    96 {{{
    97 [trac]
     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]
    98228authz_file = /path/to/svnaccessfile
    99229}}}
    100230
    101 If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add 
    102 
    103 {{{
     231If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     232
     233{{{#!ini
    104234authz_module_name = modulename
    105235}}}
    106236
    107 where ''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:
    108 
    109 {{{
    110 [trac]
     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]
    111241authz_file = /path/to/svnaccessfile
    112 authz_module_name = blahblah
     242authz_module_name = somemodule
    113243...
    114 repository_dir = /srv/active/svn/blahblah
    115 }}}
    116 
    117 where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}.
     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]}}}.
    118249
    119250'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
    120251
     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
    121259==== Subversion Configuration ====
    122260
    123261The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
    124 {{{
     262{{{#!apache
    125263<Location /repos>
    126264  DAV svn
     
    132270}}}
    133271
    134 For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
    135 
    136 == Getting TracFineGrainedPermissions to work ==
    137 
    138 Don't forget to restart Trac engine to apply new configuration if you are running tracd standalone server.
     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.
    139318
    140319----