/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
*
* Licensed 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.springframework.security.acls;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.security.access.AuthorizationServiceException;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.security.access.vote.AbstractAclVoter;
import org.springframework.security.acls.domain.ObjectIdentityRetrievalStrategyImpl;
import org.springframework.security.acls.domain.SidRetrievalStrategyImpl;
import org.springframework.security.acls.model.Acl;
import org.springframework.security.acls.model.AclService;
import org.springframework.security.acls.model.NotFoundException;
import org.springframework.security.acls.model.ObjectIdentity;
import org.springframework.security.acls.model.ObjectIdentityRetrievalStrategy;
import org.springframework.security.acls.model.Permission;
import org.springframework.security.acls.model.Sid;
import org.springframework.security.acls.model.SidRetrievalStrategy;
import org.springframework.security.core.Authentication;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* <p>
* Given a domain object instance passed as a method argument, ensures the principal has appropriate permission
* as indicated by the {@link AclService}.
* <p>
* The <tt>AclService</tt> is used to retrieve the access control list (ACL) permissions associated with a
* domain object instance for the current <tt>Authentication</tt> object.
* <p>
* The voter will vote if any {@link ConfigAttribute#getAttribute()} matches the {@link #processConfigAttribute}.
* The provider will then locate the first method argument of type {@link #processDomainObjectClass}. Assuming that
* method argument is non-null, the provider will then lookup the ACLs from the <code>AclManager</code> and ensure the
* principal is {@link Acl#isGranted(List,
* List, boolean)} when presenting the {@link #requirePermission} array to that
* method.
* <p>
* If the method argument is <tt>null</tt>, the voter will abstain from voting. If the method argument
* could not be found, an {@link AuthorizationServiceException} will be thrown.
* <p>
* In practical terms users will typically setup a number of <tt>AclEntryVoter</tt>s. Each will have a
* different {@link #setProcessDomainObjectClass processDomainObjectClass}, {@link #processConfigAttribute} and
* {@link #requirePermission} combination. For example, a small application might employ the following instances of
* <tt>AclEntryVoter</tt>:
* <ul>
* <li>Process domain object class <code>BankAccount</code>, configuration attribute
* <code>VOTE_ACL_BANK_ACCONT_READ</code>, require permission <code>BasePermission.READ</code></li>
* <li>Process domain object class <code>BankAccount</code>, configuration attribute
* <code>VOTE_ACL_BANK_ACCOUNT_WRITE</code>, require permission list <code>BasePermission.WRITE</code> and
* <code>BasePermission.CREATE</code> (allowing the principal to have <b>either</b> of these two permissions)</li>
* <li>Process domain object class <code>Customer</code>, configuration attribute
* <code>VOTE_ACL_CUSTOMER_READ</code>, require permission <code>BasePermission.READ</code></li>
* <li>Process domain object class <code>Customer</code>, configuration attribute
* <code>VOTE_ACL_CUSTOMER_WRITE</code>, require permission list <code>BasePermission.WRITE</code> and
* <code>BasePermission.CREATE</code></li>
* </ul>
* Alternatively, you could have used a common superclass or interface for the {@link #processDomainObjectClass}
* if both <code>BankAccount</code> and <code>Customer</code> had common parents.</p>
* <p>If the principal does not have sufficient permissions, the voter will vote to deny access.</p>
* <p>All comparisons and prefixes are case sensitive.</p>
*
* @author Ben Alex
*/
public class AclEntryVoter extends AbstractAclVoter {
//~ Static fields/initializers =====================================================================================
private static final Log logger = LogFactory.getLog(AclEntryVoter.class);
//~ Instance fields ================================================================================================
private AclService aclService;
private ObjectIdentityRetrievalStrategy objectIdentityRetrievalStrategy = new ObjectIdentityRetrievalStrategyImpl();
private SidRetrievalStrategy sidRetrievalStrategy = new SidRetrievalStrategyImpl();
private String internalMethod;
private String processConfigAttribute;
private List<Permission> requirePermission;
//~ Constructors ===================================================================================================
public AclEntryVoter(AclService aclService, String processConfigAttribute, Permission[] requirePermission) {
Assert.notNull(processConfigAttribute, "A processConfigAttribute is mandatory");
Assert.notNull(aclService, "An AclService is mandatory");
if ((requirePermission == null) || (requirePermission.length == 0)) {
throw new IllegalArgumentException("One or more requirePermission entries is mandatory");
}
this.aclService = aclService;
this.processConfigAttribute = processConfigAttribute;
this.requirePermission = Arrays.asList(requirePermission);
}
//~ Methods ========================================================================================================
/**
* Optionally specifies a method of the domain object that will be used to obtain a contained domain
* object. That contained domain object will be used for the ACL evaluation. This is useful if a domain object
* contains a parent that an ACL evaluation should be targeted for, instead of the child domain object (which
* perhaps is being created and as such does not yet have any ACL permissions)
*
* @return <code>null</code> to use the domain object, or the name of a method (that requires no arguments) that
* should be invoked to obtain an <code>Object</code> which will be the domain object used for ACL
* evaluation
*/
protected String getInternalMethod() {
return internalMethod;
}
public void setInternalMethod(String internalMethod) {
this.internalMethod = internalMethod;
}
protected String getProcessConfigAttribute() {
return processConfigAttribute;
}
public void setObjectIdentityRetrievalStrategy(ObjectIdentityRetrievalStrategy objectIdentityRetrievalStrategy) {
Assert.notNull(objectIdentityRetrievalStrategy, "ObjectIdentityRetrievalStrategy required");
this.objectIdentityRetrievalStrategy = objectIdentityRetrievalStrategy;
}
public void setSidRetrievalStrategy(SidRetrievalStrategy sidRetrievalStrategy) {
Assert.notNull(sidRetrievalStrategy, "SidRetrievalStrategy required");
this.sidRetrievalStrategy = sidRetrievalStrategy;
}
public boolean supports(ConfigAttribute attribute) {
return (attribute.getAttribute() != null) && attribute.getAttribute().equals(getProcessConfigAttribute());
}
public int vote(Authentication authentication, MethodInvocation object, Collection<ConfigAttribute> attributes) {
for(ConfigAttribute attr : attributes) {
if (!this.supports(attr)) {
continue;
}
// Need to make an access decision on this invocation
// Attempt to locate the domain object instance to process
Object domainObject = getDomainObjectInstance(object);
// If domain object is null, vote to abstain
if (domainObject == null) {
if (logger.isDebugEnabled()) {
logger.debug("Voting to abstain - domainObject is null");
}
return ACCESS_ABSTAIN;
}
// Evaluate if we are required to use an inner domain object
if (StringUtils.hasText(internalMethod)) {
try {
Class<?> clazz = domainObject.getClass();
Method method = clazz.getMethod(internalMethod, new Class[0]);
domainObject = method.invoke(domainObject);
} catch (NoSuchMethodException nsme) {
throw new AuthorizationServiceException("Object of class '" + domainObject.getClass()
+ "' does not provide the requested internalMethod: " + internalMethod);
} catch (IllegalAccessException iae) {
logger.debug("IllegalAccessException", iae);
throw new AuthorizationServiceException("Problem invoking internalMethod: " + internalMethod
+ " for object: " + domainObject);
} catch (InvocationTargetException ite) {
logger.debug("InvocationTargetException", ite);
throw new AuthorizationServiceException("Problem invoking internalMethod: " + internalMethod
+ " for object: " + domainObject);
}
}
// Obtain the OID applicable to the domain object
ObjectIdentity objectIdentity = objectIdentityRetrievalStrategy.getObjectIdentity(domainObject);
// Obtain the SIDs applicable to the principal
List<Sid> sids = sidRetrievalStrategy.getSids(authentication);
Acl acl;
try {
// Lookup only ACLs for SIDs we're interested in
acl = aclService.readAclById(objectIdentity, sids);
} catch (NotFoundException nfe) {
if (logger.isDebugEnabled()) {
logger.debug("Voting to deny access - no ACLs apply for this principal");
}
return ACCESS_DENIED;
}
try {
if (acl.isGranted(requirePermission, sids, false)) {
if (logger.isDebugEnabled()) {
logger.debug("Voting to grant access");
}
return ACCESS_GRANTED;
} else {
if (logger.isDebugEnabled()) {
logger.debug(
"Voting to deny access - ACLs returned, but insufficient permissions for this principal");
}
return ACCESS_DENIED;
}
} catch (NotFoundException nfe) {
if (logger.isDebugEnabled()) {
logger.debug("Voting to deny access - no ACLs apply for this principal");
}
return ACCESS_DENIED;
}
}
// No configuration attribute matched, so abstain
return ACCESS_ABSTAIN;
}
}