Changes between Version 2 and Version 3 of TracFineGrainedPermissions


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Aug 13, 2019, 3:52:01 PM (5 years 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  
     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----