Changes between Version 2 and Version 3 of TracFineGrainedPermissions


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Timestamp:
Mar 23, 2023, 6:44:37 AM (19 months ago)
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trac
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  • TracFineGrainedPermissions

    v2 v3  
     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 
    10 
    11 == Permission Policies ==
    12 
    13 A great diversity of permission policies can be implemented, and Trac comes with a few examples.
    14 
    15 Which 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.
    25 
    26 Another 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.
    27 
    28 See also [trac:source:branches/0.12-stable/sample-plugins/permissions sample-plugins/permissions] for more examples.
    29 
    30 
    31 === !AuthzPolicy ===
    32 ==== 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).
    35 * 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.
     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.
    3640* Update your `trac.ini`:
    37   1. modify the [TracIni#trac-section permission_policies] entry in the `[trac]` section
    38 {{{
    39 [trac]
    40 ...
    41 permission_policies = AuthzPolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    42 }}}
    43   1. add a new `[authz_policy]` section
    44 {{{
     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
    4548[authz_policy]
    4649authz_file = /some/trac/env/conf/authzpolicy.conf
    4750}}}
    48   1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section
    49 {{{
     51  1. enable the plugin through [/admin/general/plugin WebAdmin] or by editing the `[components]` section:
     52{{{#!ini
    5053[components]
    51 ...
    52 # Trac 0.12
    5354tracopt.perm.authz_policy.* = enabled
    54 # for Trac 0.11 use this
    55 #authz_policy.* = enabled
    56 }}}
    57 
    58 
    59 ==== 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.
     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.
    6260
    6361A 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.
    6462
    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).
     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.
    6864
    6965The `authzpolicy.conf` file is a `.ini` style configuration file:
    70 {{{
     66{{{#!ini
    7167[wiki:PrivatePage@*]
    7268john = WIKI_VIEW, !WIKI_MODIFY
     
    7470* =
    7571}}}
    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:
     72* Each section of the config is a glob pattern used to match against a Trac resource descriptor. These descriptors are in the form:
    7873{{{
    7974<realm>:<id>@<version>[/<realm>:<id>@<version> ...]
    8075}}}
    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 {{{
     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
    8779[wiki:*]
    8880[wiki:WikiStart*]
     
    9183}}}
    9284
    93   Example: Match the attachment `wiki:WikiStart@117/attachment/FOO.JPG@*`
    94   on WikiStart
    95 {{{
     85Example: Match the attachment `wiki:WikiStart@117/attachment:FOO.JPG@*` on WikiStart:
     86{{{#!ini
    9687[wiki:*]
    9788[wiki:WikiStart*]
    9889[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'''.
    108   * 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[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. ||
    113103
    114104For example, if the `authz_file` contains:
    115 {{{
     105{{{#!ini
    116106[wiki:WikiStart@*]
    117107* = WIKI_VIEW
     
    128118}}}
    129119
    130 Then: 
    131   * All versions of WikiStart will be viewable by everybody (including anonymous)
     120Then:
     121  * All versions of WikiStart will be viewable by everybody, including anonymous
    132122  * !PrivatePage will be viewable only by john
    133123  * other pages will be viewable only by john and jack
    134124
    135125Groups:
    136 {{{
     126{{{#!ini
    137127[groups]
    138128admins = john, jack
     
    155145
    156146Some repository examples (Browse Source specific):
    157 {{{
     147{{{#!ini
    158148# A single repository:
    159149[repository:test_repo@*]
    160150john = BROWSER_VIEW, FILE_VIEW
    161151# 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
    162157
    163158# All repositories:
    164159[repository:*@*]
    165160jack = BROWSER_VIEW, FILE_VIEW
    166 # John has BROWSER_VIEW and FILE_VIEW for all repositories
    167 }}}
    168 
    169 Very fine grain repository access:
    170 {{{
     161# Jack has BROWSER_VIEW and FILE_VIEW for all repositories
     162}}}
     163
     164Very granular repository access:
     165{{{#!ini
    171166# John has BROWSER_VIEW and FILE_VIEW access to trunk/src/some/location/ only
    172167[repository:test_repo@*/source:trunk/src/some/location/*@*]
    173168john = BROWSER_VIEW, FILE_VIEW
    174169
    175 
    176170# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of all files at trunk/src/some/location only
    177171[repository:test_repo@*/source:trunk/src/some/location/*@1]
    178172john = BROWSER_VIEW, FILE_VIEW
    179173
    180 
    181 # John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
     174# John has BROWSER_VIEW and FILE_VIEW access to all revisions of 'somefile' at trunk/src/some/location only
    182175[repository:test_repo@*/source:trunk/src/some/location/somefile@*]
    183176john = BROWSER_VIEW, FILE_VIEW
    184 
    185177
    186178# John has BROWSER_VIEW and FILE_VIEW access to only revision 1 of 'somefile' at trunk/src/some/location only
     
    191183Note: In order for Timeline to work/visible for John, we must add CHANGESET_VIEW to the above permission list.
    192184
    193 
    194 ==== 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]).
     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].
    196187
    197188You cannot do the following:
    198 {{{
     189{{{#!ini
    199190[groups]
    200191team1 = a, b, c
     
    204195}}}
    205196
    206 Permission groups are not supported either. You cannot do the following:
    207 {{{
     197Permission groups are not supported either, so you cannot do the following:
     198{{{#!ini
    208199[groups]
    209200permission_level_1 = WIKI_VIEW, TICKET_VIEW
     
    215206}}}
    216207
    217 === !AuthzSourcePolicy  (mod_authz_svn-like permission policy) === #AuthzSourcePolicy
    218 
    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.
     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.
    223212
    224213Example:
    225 {{{
     214{{{#!ini
    226215[/]
    227216* = r
     
    239228 * '''/branches/calc/bug-142/secret''' = ''harry has no access, sally has read access (inherited as a sub folder permission)''
    240229
    241 ==== Trac Configuration ====
    242 
    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]
     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]
    247236authz_file = /path/to/svnaccessfile
    248237}}}
    249238
    250 If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add 
    251 
    252 {{{
     239If you want to support the use of the `[`''modulename''`:/`''some''`/`''path''`]` syntax within the `authz_file`, add:
     240
     241{{{#!ini
    253242authz_module_name = modulename
    254243}}}
    255244
    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]
     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]
    260249authz_file = /path/to/svnaccessfile
    261 authz_module_name = blahblah
     250authz_module_name = somemodule
    262251...
    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]}}}.
    267 
    268 '''Note:''' Usernames inside the Authz file __must__ be the same as those used inside trac.
    269 
    270 As 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.
    271 
    272 {{{
    273 [trac]
    274 permission_policies = AuthzSourcePolicy, DefaultPermissionPolicy, LegacyAttachmentPolicy
    275 }}}
    276 
    277 ==== Subversion Configuration ====
     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
    278268
    279269The same access file is typically applied to the corresponding Subversion repository using an Apache directive like this:
    280 {{{
     270{{{#!apache
    281271<Location /repos>
    282272  DAV svn
     
    288278}}}
    289279
    290 For information about how to restrict access to entire projects in a multiple project environment see [trac:wiki:TracMultipleProjectsSVNAccess]
     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.
    291319
    292320== Debugging permissions
    293321In trac.ini set:
    294 {{{
     322{{{#!ini
    295323[logging]
    296324log_file = trac.log
     
    299327}}}
    300328
    301 And watch:
    302 {{{
     329Display the trac.log to understand what checks are being performed:
     330{{{#!sh
    303331tail -n 0 -f log/trac.log | egrep '\[perm\]|\[authz_policy\]'
    304332}}}
    305333
    306 to understand what checks are being performed. See the sourced documentation of the plugin for more info.
    307 
     334See the sourced documentation of the plugin for more info.
    308335
    309336----
    310337See also: TracPermissions,
    311 [http://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin TracHacks:FineGrainedPageAuthzEditorPlugin] for a simple editor plugin.
     338[https://trac-hacks.org/wiki/FineGrainedPageAuthzEditorPlugin FineGrainedPageAuthzEditorPlugin] for a simple editor.