/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.permissions.example;
import java.util.Set ;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.Triple;
import org.apache.jena.permissions.SecurityEvaluator ;
import org.apache.jena.rdf.model.* ;
import org.apache.jena.vocabulary.RDF ;
import org.apache.shiro.SecurityUtils ;
import org.apache.shiro.subject.Subject ;
import org.slf4j.Logger ;
import org.slf4j.LoggerFactory ;
/**
* Class to use Shiro to provide credentials.
*
* An example evaluator that only provides access to messages in the graph that
* are from or to the principal.
*
*/
public class ShiroExampleEvaluator implements SecurityEvaluator {
private static final Logger LOG = LoggerFactory.getLogger(ShiroExampleEvaluator.class);
// the model that contains the messages.
private Model model;
private RDFNode msgType = ResourceFactory.createResource( "http://example.com/msg" );
private Property pTo = ResourceFactory.createProperty( "http://example.com/to" );
private Property pFrom = ResourceFactory.createProperty( "http://example.com/from" );
/**
*
* @param model The graph we are going to evaluate against.
*/
public ShiroExampleEvaluator( Model model )
{
this.model = model;
}
/**
* We allow any action on the graph itself, so this is always true.
*/
@Override
public boolean evaluate(Object principal, Action action, Node graphIRI) {
// we allow any action on a graph.
return true;
}
/**
* This is our internal check to see if the user may access the resource.
* This method is called from the evauate(Object,Node) method.
* A user may only access the resource if they are authenticated, and are either the
* sender or the recipient.
* Additionally the admin can always see the messages.
* @param principalObj
* @param r
* @return
*/
private boolean evaluate( Object principalObj, Resource r )
{
// cast to the Subject because we know that it comes from Shiro and that
// our getPrincipal() method returns a Subject.
Subject subject = (Subject)principalObj;
if (! subject.isAuthenticated())
{
// we could throw an AuthenticationRequiredException but
// in our case we just return false.
LOG.info( "User not authenticated");
return false;
}
// a message is only available to sender or recipient
LOG.debug( "checking {}", subject.getPrincipal());
Object principal = subject.getPrincipal();
// We put the admin check here but it could have been done much earlier.
if ("admin".equals(principal.toString()))
{
return true;
}
// if we are looking at a message object then check the restrictions.
if (r.hasProperty( RDF.type, msgType ))
{
return r.hasProperty( pTo, subject.getPrincipal().toString() ) ||
r.hasProperty( pFrom, subject.getPrincipal().toString());
}
// otherwise user can see the object.
return true;
}
/**
* Check that the user can see a specific node.
* @param principal
* @param node
* @return
*/
private boolean evaluate( Object principal, Node node )
{
// Access to wild card is false -- this forces checks to the acutal nodes
// to be returned.
// we could have checked for admin access here and returned true since the admin
// can see any node.
if (node.equals( Node.ANY )) {
return false;
}
// URI nodes and blank nodes are retrieved from the model and evaluated
if (node.isURI() || node.isBlank()) {
Resource r = model.getRDFNode( node ).asResource();
return evaluate( principal, r );
}
// anything else (literals) can be seen.
return true;
}
/**
* Evaluate if the user can see the triple.
* @param principal
* @param triple
* @return
*/
private boolean evaluate( Object principal, Triple triple ) {
// we could have checked here to see if the principal was the admin and
// just returned true since the admin can perform any operation on any triple.
return evaluate( principal, triple.getSubject()) &&
evaluate( principal, triple.getObject()) &&
evaluate( principal, triple.getPredicate());
}
/**
* As per our design, users can do anything with triples they have access to, so we just
* ignore the action parameter. If we were to implement rules restricted access based
* upon action this method would sort those out appropriately.
*/
@Override
public boolean evaluate(Object principal, Action action, Node graphIRI, Triple triple) {
// we could have checked here to see if the principal was the admin and
// just returned true since the admin can perform any operation on any triple.
return evaluate( principal, triple );
}
/**
* As per our design, users can access any graph. If we were to implement rules that
* restricted user access to specific graphs, those checks would be here and we would
* return <code>false</code> if they were not allowed to access the graph. Note that this
* method is checking to see that the user may perform ALL the actions in the set on the
* graph.
*/
@Override
public boolean evaluate(Object principal, Set<Action> actions, Node graphIRI) {
return true;
}
/**
* As per our design, users can access any triple from a message that is from or to them.
* Since we don't have restrictions on actions this is no different then checking access
* for a single action.
*/
@Override
public boolean evaluate(Object principal, Set<Action> actions, Node graphIRI,
Triple triple) {
return evaluate( principal, triple );
}
/**
* As per our design, users can access any graph. If we were to implement rules that
* restricted user access to specific graphs, those checks would be here and we would
* return <code>false</code> if they were not allowed to access the graph. Note that this
* method is checking to see that the user may perform ANY of the actions in the set on the
* graph.
*/
@Override
public boolean evaluateAny(Object principal, Set<Action> actions, Node graphIRI) {
return true;
}
/**
* As per our design, users can access any triple from a message that is from or to them.
* Since we don't have restrictions on actions this is no different then checking access
* for a single action.
*/
@Override
public boolean evaluateAny(Object principal, Set<Action> actions, Node graphIRI,
Triple triple) {
return evaluate( principal, triple );
}
/**
* As per our design, users can access any triple from a message that is from or to them.
* So for an update they can only change triples they have access to into other triples
* they have access to. (e.g. they can not remvoe themself from the messsage).
*/
@Override
public boolean evaluateUpdate(Object principal, Node graphIRI, Triple from, Triple to) {
return evaluate( principal, from ) && evaluate( principal, to );
}
/**
* Return the Shiro subject. This is the subject that Shiro currently has logged in.
*/
@Override
public Object getPrincipal() {
return SecurityUtils.getSubject();
}
/**
* Verify the Shiro subject is authenticated.
*/
@Override
public boolean isPrincipalAuthenticated(Object principal) {
if (principal instanceof Subject)
{
return ((Subject)principal).isAuthenticated();
}
return false;
}
}