[Freeipa-devel] [PATCHES] 0447-0449 Add support for managed permissions

[Petr Viktorin]

On 01/23/2014 12:24 PM, Martin Kosek wrote:
> On 01/22/2014 10:27 AM, Petr Viktorin wrote:
>> On 01/08/2014 04:49 PM, Petr Viktorin wrote:
>>> Hello,
>>> This adds "managed" permissions, the framework that will make our
>>> default permissions merge IPA updates and user changes sanely.
>>>
>>> There is no updater yet, nor does this add any actual managed
>>> permissions, so there's no user-visible change (beyond help text and a
>>> disabled option). To test the patch you might need to touch LDAP directly.
>>>
>>> Ticket: https://fedorahosted.org/freeipa/ticket/4033
>>> Design (no updater & plugin changes yet):
>>> http://www.freeipa.org/page/V3/Managed_Read_permissions
>>>
>>> 0447 - Minor fixes.
>>> 0448 - Since you can't create managed permissions through the API, I
>>> needed to get creative with the declarative tests. The tests will need a
>>> custom function that adds a managed perm.
>>> 0449 - The change itself.
>>
>> ping; any thoughts on this one?
>>
>>
>
> 1) 449, the comment:
>
> +Deleting or renaming a managed permission, as well as changing its target,
> +is not supported.
> +""") + _("""
>
> I am not sure that the phrase "not supported" is the right one. It sounds to me
> like this is something we want to allow, just not implemented yet. IMO "is not
> allowed" would be better.

Makes sense.

> 2) Can you add allow_mod_for_managed flag description to parameters.py?
>
> +            flags={'no_create', 'allow_mod_for_managed'},
>
> So far we try to add all flag descriptions there.

OK

> 3) When I updated the test to not delete the testperm, I tried to show the
> managed permission and it is not entirely clear, see:
>
> # ipa permission-show testperm
>    Permission name: testperm
>    Permissions: write
> * Attributes: cn, o, sn
> * Excluded attributes: cn, sn
>    Bind rule type: all
>    Subtree: cn=users,cn=accounts,dc=example,dc=com
>    ACI target DN: uid=*,cn=users,cn=accounts,dc=example,dc=com
>    Type: user
> * Default attributes: l, o, cn
> * Effective attributes: l, o

Well, this is a tradeoff between presenting what's stored in LDAP and 
what's in the ACI.

> The "Attributes" mean actually attributes explicitly allowed by user, but it is
> not obvious from the output.
>
> Maybe it would be better to return only "Effective attributes" by default and
> return the 3 source lists only when --all is passed. But this would require us
> to let Command override LDAPObject's default_attributes, which framework cannot do.

Modifying default_attributes would not work because the 3 lists need to 
be loaded from LDAP to determine the effective attributes.
It's possible to remove the extra attributes in the post_callback, 
postprocess_result already does similar output manipulation.

> Alternatively, we may choose to use the attributes differently with managed
> permissions:
> - we add the new attributeType "ipaPermIncludedAttr". It would be used for the
> user-specified whitelist of attributes instead of ipaPermAllowedAttr
> - we do not use the ipaPermAllowedAttr with managed attributes at all or use it
> for the "Effective attributes" list
>
> My point is that the semantics of ipaPermAllowedAttr is different for managed
> and non-managed permission, so it may confuse people.

Well, the semantics are always the same (effective = (default | allowed) 
- excluded). I agree that it can be confusing; perhaps I'm in too deep 
to judge how it looks from the outside.

> For example, you may want
> to search for all permissions that allow attribute "sn":
>
> # ipa permission-find --attrs sn
> ---------------------
> 4 permissions matched
> ---------------------
>    Permission name: anon
>    Permissions: read
>    Attributes: sn
>    Bind rule type: anonymous
>    Subtree: cn=users,cn=accounts,dc=example,dc=com
>    ACI target DN: uid=*,cn=users,cn=accounts,dc=example,dc=com
>    Type: user
> ...
>    Permission name: testperm
>    Permissions: write
>    Attributes: cn, o, sn
>    Excluded attributes: cn, sn
>    Bind rule type: anonymous
>    Subtree: cn=users,cn=accounts,dc=example,dc=com
>    ACI target DN: uid=*,cn=users,cn=accounts,dc=example,dc=com
>    Type: user
>    Default attributes: l, o, cn
>    Effective attributes: l, o
> ...
>
> As you see, it matched both testperm and anon even though testperm does not
> really allow sn as it excluded.
>
> Thoughts?

Well, we could have default, included, excluded attributes stored in 
LDAP as now (using the name "included" instead of "allowed"), and make 
effective attributes (--attrs) into an updatable virtual attribute: when 
setting it, IPA would consult the "default" attributes and update 
"included"/"excluded" accordingly. (With non-managed permissions 
"default" is empty, so only "included" would be updated.) And searching 
on --attrs would construct an appropriate filter.

I thought about this approach earlier but thought that it obscured 
what's actually stored in LDAP. Given recent discussions I'm now 
thinking I shouldn't have rejected it.


-- 
Petr³