Changes between Version 3 and Version 4 of TracFineGrainedPermissions


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Timestamp:
May 4, 2020, 5:16:28 PM (5 years ago)
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trac
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  • TracFineGrainedPermissions

    v3 v4  
     1= Fine grained permissions =
    12[[PageOutline(2-5, Contents, floated)]]
    2 = Fine grained permissions =
    3 
    4 Before Trac 0.11, it was only possible to define fine-grained permissions checks on the repository browser sub-system.
    5 
    6 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.
    7 
    8 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.
    9 
     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.
    108
    119== Permission Policies ==
    1210
    13 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.
    1412
    1513Which policies are currently active is determined by a configuration setting in TracIni:
    16 e.g.
    17 {{{
    18 [trac]
    19 permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    20 }}}
    21 This 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 
    23 Among 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.
     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.
    2523
    2624Another 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.
    2725
    28 See also [trac:source:branches/0.12-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
    29 
     26See also [trac:source:branches/1.0-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
    3027
    3128=== !AuthzPolicy ===
    3229==== 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).
    3530* 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.
    3631* Update your `trac.ini`:
    37   1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section
    38 {{{
     32  1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section:
     33{{{#!ini
    3934[trac]
    4035...
    41 permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    42 }}}
    43   1. add a new `[authz_policy]` section
    44 {{{
     36permission_policies = AuthzPolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     37}}}
     38  1. add a new `[authz_policy]` section:
     39{{{#!ini
    4540[authz_policy]
    4641authz_file = /some/trac/env/conf/authzpolicy.conf
    4742}}}
    48   1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section
    49 {{{
     43  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     44{{{#!ini
    5045[components]
    51 ...
    52 # Trac 0.12
    5346tracopt.perm.authz_policy.* = enabled
    54 # for Trac 0.11 use this
    55 #authz_policy.* = enabled
    56 }}}
    57 
     47}}}
    5848
    5949==== Usage Notes ====
    60 Note that the order in which permission policies are specified is quite critical,
    61 as policies will be examined in the sequence provided.
     50
     51Note the order in which permission policies are specified: policies are implemented in the sequence provided and therefore may override earlier policy specifications.
    6252
    6353A 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.
    6454
    65 NOTE: Only if the return value is `None` will the ''next'' permission policy be consulted.
    66 If none of the policies explicitly grants the permission, the final result will be `False`
    67 (i.e. permission denied).
     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.
    6856
    6957The `authzpolicy.conf` file is a `.ini` style configuration file:
    70 {{{
     58{{{#!ini
    7159[wiki:PrivatePage@*]
    7260john = WIKI_VIEW, !WIKI_MODIFY
    … …  
    7462* =
    7563}}}
    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:
     64* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
    7865{{{
    7966<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
    8067}}}
    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 {{{
     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
    8771[wiki:*]
    8872[wiki:WikiStart*]
    … …  
    9175}}}
    9276
    93   Example: Match the attachment `wiki:WikiStart@117/attachment/FOO.JPG@*`
    94   on WikiStart
    95 {{{
     77Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     78{{{#!ini
    9679[wiki:*]
    9780[wiki:WikiStart*]
    9881[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'''.
     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'''.
    10889  * 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 ||
     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. ||
    11393
    11494For example, if the `authz_file` contains:
    115 {{{
     95{{{#!ini
    11696[wiki:WikiStart@*]
    11797* = WIKI_VIEW
    … …  
    129109
    130110Then:
    131   * All versions of WikiStart will be viewable by everybody (including anonymous)
     111  * All versions of WikiStart will be viewable by everybody, including anonymous
    132112  * !PrivatePage will be viewable only by john
    133113  * other pages will be viewable only by john and jack
    134114
    135115Groups:
    136 {{{
     116{{{#!ini
    137117[groups]
    138118admins = john, jack
    … …  
    155135
    156136Some repository examples (Browse Source specific):
    157 {{{
     137{{{#!ini
    158138# A single repository:
    159139[repository:test_repo@*]
    160140john = BROWSER_VIEW, FILE_VIEW
    161141# 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
    162147
    163148# All repositories:
    164149[repository:*@*]
    165150jack = BROWSER_VIEW, FILE_VIEW
    166 # John has BROWSER_VIEW and FILE_VIEW for all repositories
    167 }}}
    168 
    169 Very fine grain repository access:
    170 {{{
     151# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     152}}}
     153
     154Very granular repository access:
     155{{{#!ini
    171156# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
    172157[repository:test_repo@*/source:trunk/src/some/location/*@*]
    173158john = BROWSER_VIEW, FILE_VIEW
    174159
    175 
    176160# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
    177161[repository:test_repo@*/source:trunk/src/some/location/*@1]
    178162john = BROWSER_VIEW, FILE_VIEW
    179163
    180 
    181164# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
    182165[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
    183166john = BROWSER_VIEW, FILE_VIEW
    184167
    185 
    186168# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
    187169[repository:test_repo@*/source:trunk/src/some/location/somefile@1]
    … …  
    191173Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
    192174
    193 
    194175==== Missing Features ====
    195 Although 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]).
     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].
    196177
    197178You cannot do the following:
    198 {{{
     179{{{#!ini
    199180[groups]
    200181team1 = a, b, c
    … …  
    204185}}}
    205186
    206 Permission groups are not supported either. You cannot do the following:
    207 {{{
     187Permission groups are not supported either, so you cannot do the following:
     188{{{#!ini
    208189[groups]
    209190permission_level_1 = WIKI_VIEW, TICKET_VIEW
    … …  
    217198=== !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
    218199
    219 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.
    220 
    221 That kind of fine-grained permission control needs a definition file, which is the one used by Subversion's mod_authz_svn.
    222 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.
     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.
    223204
    224205Example:
    225 {{{
     206{{{#!ini
    226207[/]
    227208* = r
    … …  
    241222==== Trac Configuration ====
    242223
    243 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.
    244 
    245 {{{
    246 [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]
    247228authz_file = /path/to/svnaccessfile
    248229}}}
    249230
    250 If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add 
    251 
    252 {{{
     231If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     232
     233{{{#!ini
    253234authz_module_name = modulename
    254235}}}
    255236
    256 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:
    257 
    258 {{{
    259 [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]
    260241authz_file = /path/to/svnaccessfile
    261 authz_module_name = blahblah
     242authz_module_name = somemodule
    262243...
    263 repository_dir = /srv/active/svn/blahblah
    264 }}}
    265 
    266 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]}}}.
    267249
    268250'''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
    … …  
    270252As 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.
    271253
    272 {{{ 
    273 [trac]
    274 permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
     254{{{#!ini
     255[trac]
     256permission_policies = AuthzSourcePolicy, ReadonlyWikiPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    275257}}}
    276258
    … …  
    278260
    279261The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
    280 {{{
     262{{{#!apache
    281263<Location /repos>
    282264  DAV svn
    … …  
    288270}}}
    289271
    290 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].
     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.
    291302
    292303== Debugging permissions
    293304In trac.ini set:
    294 {{{
     305{{{#!ini
    295306[logging]
    296307log_file = trac.log
    … …  
    299310}}}
    300311
    301 And watch:
    302 {{{
     312Display the trac.log to understand what checks are being performed:
     313{{{#!sh
    303314tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
    304315}}}
    305316
    306 to understand what checks are being performed. See the sourced documentation of the plugin for more info.
    307 
     317See the sourced documentation of the plugin for more info.
    308318
    309319----