Changes between Version 1 and Version 2 of TracFineGrainedPermissions


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Timestamp:
Apr 24, 2017, 10:36:27 AM (2 months ago)
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trac
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  • TracFineGrainedPermissions

    v1 v2  
    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 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 
     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.
    98
    109== Permission Policies ==
    1110
    12 A great diversity of permission policies can be implemented, and Trac comes with a few examples.
     11A great diversity of permission policies can be implemented and Trac comes with a few examples.
    1312
    1413Which policies are currently active is determined by a configuration setting in TracIni:
    15 e.g.
    16 {{{
     14
     15{{{#!ini
    1716[trac]
    1817permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     
    2019This 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.
    2120
    22 Among 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.
     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.
    2423
    2524Another 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.
    2625
    27 See also [trac:source:branches/0.12-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
    28 
     26See also [trac:source:branches/1.0-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
    2927
    3028=== !AuthzPolicy ===
    31 
    32  - Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj] (required).
    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 {{{
     29==== Configuration ====
     30* Install [http://www.voidspace.org.uk/python/configobj.html ConfigObj].
     31* 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.
     32* Update your `trac.ini`:
     33  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section:
     34{{{#!ini
    3835[trac]
    3936...
    4037permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    4138}}}
    42    2. add a new `[authz_policy]` section
    43 {{{
     39  1. add a new `[authz_policy]` section:
     40{{{#!ini
    4441[authz_policy]
    4542authz_file = /some/trac/env/conf/authzpolicy.conf
    4643}}}
    47    3. enable the single file plugin
     44  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     45{{{#!ini
     46[components]
     47tracopt.perm.authz_policy.* = enabled
     48}}}
     49
     50==== Usage Notes ====
     51
     52Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
     53
     54A 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.
     55
     56NOTE: 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.
     57
     58The `authzpolicy.conf` file is a `.ini` style configuration file:
     59{{{#!ini
     60[wiki:PrivatePage@*]
     61john = WIKI_VIEW, !WIKI_MODIFY
     62jack = WIKI_VIEW
     63* =
     64}}}
     65* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
    4866{{{
    49 [components]
    50 ...
    51 # Trac 0.12
    52 tracopt.perm.authz_policy.* = enabled
    53 # for Trac 0.11 use this
    54 #authz_policy.* = enabled
    55 }}}
    56 
    57 Note that the order in which permission policies are specified is quite critical,
    58 as policies will be examined in the sequence provided.
    59 
    60 A policy will return either `True`, `False` or `None` for a given permission check.
    61 Only if the return value is `None` will the ''next'' permission policy be consulted.
    62 If no policy explicitly grants the permission, the final result will be `False`
    63 (i.e. no permission).
     67<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
     68}}}
     69
     70Resources 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:
     71{{{#!ini
     72[wiki:*]
     73[wiki:WikiStart*]
     74[wiki:WikiStart@*]
     75[wiki:WikiStart]
     76}}}
     77
     78Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     79{{{#!ini
     80[wiki:*]
     81[wiki:WikiStart*]
     82[wiki:WikiStart@*]
     83[wiki:WikiStart@*/attachment:*]
     84[wiki:WikiStart@117/attachment:FOO.JPG]
     85}}}
     86
     87* Sections are checked against the current Trac resource descriptor '''IN ORDER''' of appearance in the configuration file. '''ORDER IS CRITICAL'''.
     88
     89* Once a section matches, the current username is matched against the keys (usernames) of the section, '''IN ORDER'''.
     90  * If a key (username) is prefixed with a `@`, it is treated as a group.
     91  * If a value (permission) is prefixed with a `!`, the permission is denied rather than granted.
     92
     93The 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. ||
    6494
    6595For example, if the `authz_file` contains:
    66 {{{
     96{{{#!ini
    6797[wiki:WikiStart@*]
    6898* = WIKI_VIEW
     
    70100[wiki:PrivatePage@*]
    71101john = WIKI_VIEW
    72 * =
     102* = !WIKI_VIEW
    73103}}}
    74104and the default permissions are set like this:
     
    80110
    81111Then:
    82  - All versions of WikiStart will be viewable by everybody (including anonymous)
    83  - !PrivatePage will be viewable only by john
    84  - other pages will be viewable only by john and jack
    85 
     112  * All versions of WikiStart will be viewable by everybody, including anonymous
     113  * !PrivatePage will be viewable only by john
     114  * other pages will be viewable only by john and jack
     115
     116Groups:
     117{{{#!ini
     118[groups]
     119admins = john, jack
     120devs = alice, bob
     121
     122[wiki:Dev@*]
     123@admins = TRAC_ADMIN
     124@devs = WIKI_VIEW
     125* =
     126
     127[*]
     128@admins = TRAC_ADMIN
     129* =
     130}}}
     131
     132Then:
     133- everything is blocked (whitelist approach), but
     134- admins get all TRAC_ADMIN everywhere and
     135- devs can view wiki pages.
     136
     137Some repository examples (Browse Source specific):
     138{{{#!ini
     139# A single repository:
     140[repository:test_repo@*]
     141john = BROWSER_VIEW, FILE_VIEW
     142# John has BROWSER_VIEW and FILE_VIEW for the entire test_repo
     143
     144# The default repository (requires Trac 1.0.2 or later):
     145[repository:@*]
     146john = BROWSER_VIEW, FILE_VIEW
     147# John has BROWSER_VIEW and FILE_VIEW for the entire default repository
     148
     149# All repositories:
     150[repository:*@*]
     151jack = BROWSER_VIEW, FILE_VIEW
     152# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     153}}}
     154
     155Very granular repository access:
     156{{{#!ini
     157# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
     158[repository:test_repo@*/source:trunk/src/some/location/*@*]
     159john = BROWSER_VIEW, FILE_VIEW
     160
     161# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
     162[repository:test_repo@*/source:trunk/src/some/location/*@1]
     163john = BROWSER_VIEW, FILE_VIEW
     164
     165# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     166[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
     167john = BROWSER_VIEW, FILE_VIEW
     168
     169# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     170[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
     171john = BROWSER_VIEW, FILE_VIEW
     172}}}
     173
     174Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
     175
     176==== Missing Features ====
     177Although 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].
     178
     179You cannot do the following:
     180{{{#!ini
     181[groups]
     182team1 = a, b, c
     183team2 = d, e, f
     184team3 = g, h, i
     185departmentA = team1, team2
     186}}}
     187
     188Permission groups are not supported either, so you cannot do the following:
     189{{{#!ini
     190[groups]
     191permission_level_1 = WIKI_VIEW, TICKET_VIEW
     192permission_level_2  = permission_level_1, WIKI_MODIFY, TICKET_MODIFY
     193[*]
     194@team1 = permission_level_1
     195@team2 = permission_level_2
     196@team3 = permission_level_2, TICKET_CREATE
     197}}}
    86198
    87199=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
    88200
    89 At 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.
    90 
    91 That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
    92 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.
     201At 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.
     202
     203That kind of granular permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
     204More 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.
    93205
    94206Example:
    95 {{{
     207{{{#!ini
    96208[/]
    97209* = r
     
    111223==== Trac Configuration ====
    112224
    113 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.
    114 
    115 {{{
     225To activate granular 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.
     226
     227{{{#!ini
    116228[trac]
    117229authz_file = /path/to/svnaccessfile
    118230}}}
    119231
    120 If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add 
    121 
    122 {{{
     232If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     233
     234{{{#!ini
    123235authz_module_name = modulename
    124236}}}
    125237
    126 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:
    127 
    128 {{{
     238where ''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/somemodule}}}, that would yield the following:
     239
     240{{{ #!ini
    129241[trac]
    130242authz_file = /path/to/svnaccessfile
    131 authz_module_name = blahblah
     243authz_module_name = somemodule
    132244...
    133 repository_dir = /srv/active/svn/blahblah
    134 }}}
    135 
    136 where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[blahblah:/some/path]}}}.
     245repository_dir = /srv/active/svn/somemodule
     246}}}
     247
     248where the svn access file, {{{/path/to/svnaccessfile}}}, contains entries such as {{{[somemodule:/some/path]}}}.
    137249
    138250'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
     
    140252As 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.
    141253
    142 {{{ 
     254{{{#!ini
    143255[trac]
    144256permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     
    148260
    149261The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
    150 {{{
     262{{{#!apache
    151263<Location /repos>
    152264  DAV svn
     
    158270}}}
    159271
    160 For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
     272For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess].
    161273
    162274== Debugging permissions
    163275In trac.ini set:
    164 {{{
     276{{{#!ini
    165277[logging]
    166278log_file = trac.log
     
    169281}}}
    170282
    171 And watch:
    172 {{{
     283Display the trac.log to understand what checks are being performed:
     284{{{#!sh
    173285tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
    174286}}}
    175287
    176 to understand what checks are being performed. See the sourced documentation of the plugin for more info.
    177 
     288See the sourced documentation of the plugin for more info.
    178289
    179290----