001/* 002 Licensed to the Apache Software Foundation (ASF) under one 003 or more contributor license agreements. See the NOTICE file 004 distributed with this work for additional information 005 regarding copyright ownership. The ASF licenses this file 006 to you under the Apache License, Version 2.0 (the 007 "License"); you may not use this file except in compliance 008 with the License. You may obtain a copy of the License at 009 010 http://www.apache.org/licenses/LICENSE-2.0 011 012 Unless required by applicable law or agreed to in writing, 013 software distributed under the License is distributed on an 014 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 KIND, either express or implied. See the License for the 016 specific language governing permissions and limitations 017 under the License. 018 */ 019package org.apache.wiki.api.core; 020 021import java.security.Permission; 022import java.security.Principal; 023import java.util.Enumeration; 024 025 026/** 027 * <p> 028 * Defines an access control list (ACL) for wiki pages. An Access Control List is a data structure used to guard access to resources. 029 * An ACL can be thought of as a data structure with multiple ACL entries. Each ACL entry, of interface type AclEntry, contains a set 030 * of positive permissions associated with a particular principal. (A principal represents an entity such as an individual user or a 031 * group). The ACL Entries in each ACL observe the following rules: 032 * </p> 033 * <ul> 034 * <li>Each principal can have at most one ACL entry; that is, multiple ACL entries are not allowed for any principal. Each entry 035 * specifies the set of permissions that are to be granted</li> 036 * <li>If there is no entry for a particular principal, then the principal is considered to have a null (empty) permission set</li> 037 * </ul> 038 * <p> 039 * This interface is a highly stripped-down derivation of the java.security.acl.Acl interface. In particular, the notion of an Acl "owner" 040 * has been eliminated, since JSPWiki pages do not have owners. An additional simplification compared to the standard Java package is that 041 * negative permissions have been eliminated. Instead, JSPWiki assumes a "default-deny" security stance: principals are granted no 042 * permissions by default, and posesses only those that have been explicitly granted to them. And finally, the getPermissions() and 043 * checkPermission() methods have been eliminated due to the complexities associated with resolving Role principal membership. 044 * </p> 045 * @since 2.3 046 */ 047public interface Acl { 048 049 /** 050 * Adds an ACL entry to this ACL. An entry associates a principal (e.g., an individual or a group) with a set of permissions. 051 * Each principal can have at most one positive ACL entry, specifying permissions to be granted to the principal. If there is 052 * already an ACL entry already in the ACL, false is returned. 053 * 054 * @param entry - the ACL entry to be added to this ACL 055 * @return true on success, false if an entry of the same type (positive or negative) for the same principal is already present 056 * in this ACL 057 */ 058 boolean addEntry( AclEntry entry ); 059 060 /** 061 * Returns an enumeration of the entries in this ACL. Each element in the enumeration is of type AclEntry. 062 * 063 * @return an enumeration of the entries in this ACL. 064 */ 065 Enumeration< AclEntry > aclEntries(); 066 067 /** 068 * Returns <code>true</code>, if this Acl is empty. 069 * 070 * @return the result 071 * @since 2.4.68 072 */ 073 boolean isEmpty(); 074 075 /** 076 * Returns all Principal objects assigned a given Permission in the access control list. The Princiapls returned are those that 077 * have been granted either the supplied permission, or a permission implied by the supplied permission. Principals are not 078 * "expanded" if they are a role or group. 079 * 080 * @param permission the permission to search for 081 * @return an array of Principals posessing the permission 082 */ 083 Principal[] findPrincipals( Permission permission ); 084 085 /** 086 * Returns an AclEntry for a supplied Principal, or <code>null</code> if the Principal does not have a matching AclEntry. 087 * 088 * @param principal the principal to search for 089 * @return the AclEntry associated with the principal, or <code>null</code> 090 */ 091 AclEntry getAclEntry( Principal principal ); 092 093 /** 094 * Removes an ACL entry from this ACL. 095 * 096 * @param entry the ACL entry to be removed from this ACL 097 * @return true on success, false if the entry is not part of this ACL 098 */ 099 boolean removeEntry( AclEntry entry ); 100 101}