6.0.0-git
2024-03-28

Diff for Project/HordePolicy between 23 and 24

[[toc]]



+ Horde Policies



The idea of Horde Policy is to implement a replacement for the current prefs system, modeled after how Group Policy Objects work in a Microsoft Active Directory.  Including a nice administrative GUI, meaning no more editing prefs.php files, and happier admins.



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++ Visualization of a Horde Policy



<code>

policy

|-- name

|-- targets

|   |-- target1

|   `-- target2

|-- app1 (ie, imp)

`-- app2 (ie, turba)

    |--attribute-group1

    |   |-- attribute-group2

    |   |   `-- attribute1

    |   |       `-- value

    |   `-- attribute2

    |       `-- value

    `-- attribute3

        `-- value

</code>

* each app would have a policy.xml file defining what policy attributes are available.

* A target can consist of one or more:

 * default (applies to entire installation)

 * horde application (including 'horde')

 * horde group

 * individual user

 * guest user

 * OU if using LDAP backend



This


This structure should be easy to cache when a given app is loaded.  something like {{ if (!isset($policy[$app])) { load $policy[$app] from xml } }}.



Not something that we would really enforce in code, but we could have an organizational convention that we stick to in the xml files, so that each app has a common policy structure.  Something like 'prefs', 'config', 'backends', 'servers', etc.



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++ What would need to be done



* build a Horde Policy manager to list, create, edit, delete, etc. policies.

* Store Horde Policies in DB table(s)

 * horde_policy table(s)?

 * extend the datatree?  The data structure fits perfectly with a few performance tweaks


<code>

horde_policy

------------

policy_name

</code>


-----------------------

policy_id

attribute_name

attribute_scope

attribute_state  <-- mask for things like enabled, disabled, overridable, etc.

attribute_hook  <-- if defined, use it to get the default value for this attribute.

attribute_type  <-- what data type are we working with?

attribute_value

</code>



<code>

horde_policy_targets

--------------------

policy_id

target_id  <-- uid, gid, app-name, or global/default

target_type  <-- 'uid', 'gid', 'app', or 'global'/'default'

</code>



We can get the attribute group structure from the XML file.  No need to worry about storing it, just need to enforce that all attributes for a given app have unique names.  If there are two attributes with the same name, we should use the last one found in the XML file.



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++ Cascading Heirarchy



Listed by priority, highest-priority first.  All levels would need to be checked, though, as some lower level might have the overridable bit set to false.



* **user-defined** - value defined by the user.

* **uid** - policy applied directly to the current user.

* **gid** - policy applied to a group that the current user is a member of.

* **app** - policy applied to current app, including 'horde'

* **root** - default "root" policy, always present.app

* **default** - default value pulled from XML file.



I haven't decided if it would be better to check from top to bottom, or bottom to top.  bottom-to-top would give us quicker results if overridable is false at any level.  top-to-bottom would give us



When loading a policy, we should go bottom-to-top in this list.  Any new values in higher levels can just overwrite the values found in lower levels, unless a lower level has specified that the "real" value faster, assuming overridable is not false at some lower level.



Also, weoverridable.



We need toto work out a way to resolve collisions at a given level.  For example, a user might be a member of various groups, and each group might have a different value set for aa given attribute.  If there is not a value set at aa higher level, how do we decide which takes priority?  Sort alphabetically?  Give a priority to overridable?  Add documentation saying that this behaviour is undefined and leave it up to admins to avoid collisions?



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++ Cache



At login, all applicable Policies should be loaded and cached.  We should also try to do something to cache Policies for guest sessions.



Could we use Horde_Cache for this?



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++ Other Thoughts



* all $pref->getValue() calls could be handled on the backend by writing a Policy driver for the Prefs system, giving us a drop-in replacement.

* we'd need a way to clearly define what happens if two Horde Policies have overlapping, conflicting settings.

* there should be a default "root" policy, which cannot be detached from the root installation.  This policy would be a site-wide policy that always exists.

* Should we keep a history of who created or edited a policy?  Can we use the history classes for this?

* Hooks should definitely come into play somehow.  Perhaps store the name of the hook function with the attribute, where there is no hook if this is null?

* Do we need a Policy "manager" object like we have with the DataTree?  Or should we include static functions to Horde_Policy?  do static functions get copied for each instance of an object?  If so, the "manager" object might be the way to go.



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++ API



Some thoughts about an API for Horde_Policy



<code type=php">

class Horde_Policy {

    var $name // policy name

    var $targets // array of targets

    var $attributes // array of attributes

    var $_params // storage parameters

    function name($name) {} // get/set policy name

    function attribute($attribute, $params) // set given attribute

    function addTarget()

    function removeTarget()

    function listTargets()

    static function getPolicyAttribute($attribute) // go through the cascading heirarchy, and return the value with priority (see Cascading Heirarchy above)

}

</code>



Still need to be able to read from XML, not sure if that should be put in the constructor, or in the public API.  Also need to be able to save to backend somehow.



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++ What happens when applying a Horde Policy



* read XML file(s) to set up internal attribute tree with default values.

* see if any policies target the current user, if so...

 * go through target cascade (see above), pulling values from SQL

 * overwrite default values with values pulled from SQL

* cache



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++ Links



http://www.microsoft.com/technet/itsolutions/msit/security/grppolobjectmgmt.mspx - gives a good overview on how MS GPO's work, and a nice graphic that really helped me visualize the internal workings.



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++ Cut & Paste from mailing list until I can better organize my thoughts



> - with something like this in place I think it would make more and

> more sense to move everything that's at all user-related in conf.php

> files to this system. Things like "user capabilities" in both Horde

> and IMP - they can even be locked (overridable = false?) by default,

> but letting people easily manage them on a per-group basis, or

> whatever, sounds very good to me.


> backend configurations (sieve servers, etc.) using this system, that

> would be even better.



Yes!  We could put IMAP server configs, etc. in a GPO and assign to targets as necessary.  Same way that printers can be assigned in an active directory.  "group A uses this IMAP server, group B uses this other IMAP server, group C gets to specify their own IMAP server." The possibilities are endless! I love it!



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Notes:



**Horde_Policy** - name(sql), settings(xml), targets(sql)



**Horde_Policy_Target** - target(sql)



**Horde_Policy_Setting**(xml) - name, desc, attributes

* Setting status can be stored in an attribute

* Extend Horde_Policy_Attribute to allow other Horde_Policy_Settings in the attributes list.



**Horde_Policy_Attribute** - name(sql), type(xml), value(sql), hook(sql)

* by incorporating a "type" in the xml, we can store a serialized array for dynamic lists (ie, IMAP servers).