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From David Jencks <david_jen...@yahoo.com>
Subject TripleSec-Geronimo integration
Date Sat, 14 Oct 2006 22:37:14 GMT
I had a great conversation with Alex Karasulu at Apachecon about  
integrating TripleSec into geronimo as a JACC provider.  I think this  
will be pretty easy to do and provide a very powerful security  
management capability for geronimo.  I'll try to describe my  
understanding of our conclusions about what needs to be done.  My  
understanding of TripleSec is based entirely on Alex's brief  
descriptions so any inaccuracies should be blamed entirely on me :-)

Data Model

The TripleSec datamodel needs some changes to fit with java  
permissions and the j2ee permissions categories of unchecked,  
excluded, and role-mapped.  To review for those who may not have  
reviewed their JACC recently :-)  the unchecked and excluded  
permissions apply to all users without regard to who they are or what  
roles they might be in whereas the role-mapped permissions grant  
permission based on the users current roles.

- permissions.  IIUC the current TS permission model uses  
String.equals to implement Permission.implies(Permission).  This  
doesn't work well with things like web permissions where you can be  
granted permission to see /context-root/public/* but  excluded from  
seeing /context-root/public/area/secret/*.  I think that it will be  
much more powerful to support storing actual java Permission objects  
in LDAP and delegating the implies to the actual Permission  
implementation.  Use of Permission.implies is required for a JACC  
implementation.   I think simply serializing the permissions and  
saving the bytes as well as saving the toString() name for  
identification will work OK for an initial implementation: Alex  
suggested using StateFactory and ObjectFactory for a more  
sophisticated implementation that would store more meaningful info.

-role-mapped permissions are supported well by TS role-principal  
mapping and profiles.

- unchecked permissions are not currently supported by TS.  I think  
these can be supported by having an "unchecked" role and granting it  
to all users.

- excluded permissions are not currently supported by TS.  I think  
the best way to support them is by modifying Profile to include a set  
of denied roles along with the existing granted roles and granted and  
denied individual permissions.  The excluded permissions can be  
modeled as a role denied to everyone.

With this proposed change Profile would contain a userId, an  
applicationId, a set of granted roles, a set of denied roles, a set  
of granted permissions, and a set of denied permissions.

The effective permissions set needs to contain both granted and  
denied permissions since a denied permission will generally not  
exactly match any granted permission.  So, the granted permissions  
would be the union of permissions from the profile's granted roles  
together with the individual granted permissions, and the denied  
permissions would be the union of permissions from the profiles  
denied roles together with  the individual denied permissions.

The TS LoginModule needs to generate a subject from which the granted  
and denied permissions can be extracted for each applicationId.  The  
simplest way I can think of to do this is to use a TSPrincipal that  
contains a map of applicationId to an object containing the granted  
and denied permissions.

The JACC policyContextId seems to correspond well to the TS  
applicationId.

JACC integration.

We can divide this into runtime policy enforcement and deployment  
time policy configuration.

-runtime.  Following normal methods the user logs into a security  
realm that uses a TSLoginModule producing a TSPrincipal containing  
the effective permissions as described above.  When a permissions  
check is done, as usual the decision is delegated to the  
PolicyConfiguration for the policyContextId: this checks the  
permission in question against first the denied permissions and (if  
not denied) the granted permissions, per the following simple code:

     public boolean implies(ProtectionDomain domain, Permission  
permission) {

         Principal[] principals = domain.getPrincipals();
         if (principals.length == 0) return false;

         for (int i = 0; i < principals.length; i++) {
             Principal principal = principals[i];
             if (principal instanceof TripleSecPrincipal) {
                 PermissionsHolder permissionsHolder =  
((TripleSecPrincipal)principal).getPermissionsHolder(contextID);

                 Permissions denied = permissionsHolder.getDenied();
                 if (denied.implies(permission)) return false;

                 Permissions granted = permissionsHolder.getGranted();
                 //only look for one TripleSec permission
                 return granted.implies(permission);

             }
         }
         // if no TripleSec principal found, deny access.
         return false;
     }

This part will just work in geronimo after configuring a security  
realm using the TSLoginModule and specifying  
TSPolicyConfigurationFactory as the JACC provider.


-deployment time.  Currently geronimo waits until the application  
starts to install the permissions into  the JACC provider.  I think  
this is primarily because we don't have a persistent store for these  
permissions, although the spec might have something to say about this  
as well (I don't remember).  Since TS definitely has a persistent  
store, I think it would be more appropriate to install the spec  
permissions when the application is converted into a geronimo module  
(car file).  This gives the security administrators time to configure  
the users profiles.  I don't know when it would be appropriate to  
remove an applications permission info from TS, nor do I have an idea  
how redeployment with changed permissions might work.  I'm hoping  
that after we get the basics described above done it will be clearer  
how to deal with application evolution.

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

I spent a few minutes and wrote up the start of most of the classes  
needed for the integration.  I put them at https://svn.apache.org/ 
repos/asf/geronimo/sandbox/triplesec

TSPolicyConfigurationFactory --- this is probably complete.
TSPolicyConfiguration  -- the implies method is probably complete.   
The methods for adding and removing permissions need to be hooked up  
to TS.  It's not entirely clear to me exactly what the open(remove)  
method should do.  This is basically the application evolution  
question I mentioned above, and we probably don't have to answer it  
until we get everything else working.
TSPrincipal -- this is a very simple implementation of something that  
meets the needs of the TSPolicyConfiguration.  If I understaood Alex  
correctly the existing TSPrincipal gets updated when the data in LDAP  
changes.  I'm hoping that the additional complexity of having both  
granted and denied permissions will not make this significantly harder.

TSSecurityBuilder.  This is a Geronimo Security builder.  Basically  
it has no knowledge of TS whatsoever and just uses the JACC  
interfaces to install the spec defined security info into the  
PolicyConfigurations during deployment.  There are a couple of  
methods that I don't know how to implement, and they remind me that  
at last years ApacheCon Simon Godik pointed out that all Subjects  
used in geronimo should be derived by logging some user into the  
appropriate security realm.  If we had taken his good advice these  
methods would not be there to cause problems.  I think its time we  
changed to this model.  Meanwhile I don't think that the  
implementation hole will affect TS integration" its used for  
specifying default users and run-as subjects.

The TSSecurityBuilder IMO should be moved into geronimo core since it  
can be used with any jacc provider that provides a persistent store.   
The other classes I think should move to TS.  I plan to be working  
with Alex and anyone else who is interested over the next few weeks  
to get this into a working state.  Ideally I'd like to see it as a  
geronimo plugin released with geronimo 1.2.

I also opened GERONIMO-2497 to help tracking progress on this.


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

On a mostly unrelated note I recall that jetspeed2 has a security  
administration portlet app for their security system that has some  
feature overlap with TS.  I wonder if it would be possible to use  
this as a start for developing a web front end for TS.

thanks
david jencks





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