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Diffstat (limited to 'base/util/src/netscape/security/acl/AclImpl.java')
-rw-r--r-- | base/util/src/netscape/security/acl/AclImpl.java | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/base/util/src/netscape/security/acl/AclImpl.java b/base/util/src/netscape/security/acl/AclImpl.java new file mode 100644 index 000000000..76750b7b9 --- /dev/null +++ b/base/util/src/netscape/security/acl/AclImpl.java @@ -0,0 +1,391 @@ +// --- BEGIN COPYRIGHT BLOCK --- +// This program is free software; you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation; version 2 of the License. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License along +// with this program; if not, write to the Free Software Foundation, Inc., +// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +// +// (C) 2007 Red Hat, Inc. +// All rights reserved. +// --- END COPYRIGHT BLOCK --- +package netscape.security.acl; + +import java.security.Principal; +import java.security.acl.Acl; +import java.security.acl.AclEntry; +import java.security.acl.Group; +import java.security.acl.NotOwnerException; +import java.security.acl.Permission; +import java.util.Enumeration; +import java.util.Hashtable; +import java.util.NoSuchElementException; +import java.util.Vector; + +/** + * An Access Control List (ACL) is encapsulated by this class. + * + * @author Satish Dharmaraj + */ +public class AclImpl extends OwnerImpl implements Acl { + // + // Maintain four tables. one each for positive and negative + // ACLs. One each depending on whether the entity is a group + // or principal. + // + private Hashtable<Principal, AclEntry> allowedUsersTable = new Hashtable<Principal, AclEntry>(23); + private Hashtable<Principal, AclEntry> allowedGroupsTable = new Hashtable<Principal, AclEntry>(23); + private Hashtable<Principal, AclEntry> deniedUsersTable = new Hashtable<Principal, AclEntry>(23); + private Hashtable<Principal, AclEntry> deniedGroupsTable = new Hashtable<Principal, AclEntry>(23); + private String aclName = null; + private Vector<Permission> zeroSet = new Vector<Permission>(1, 1); + + /** + * Constructor for creating an empty ACL. + */ + public AclImpl(Principal owner, String name) { + super(owner); + try { + setName(owner, name); + } catch (Exception e) { + } + } + + /** + * Sets the name of the ACL. + * + * @param caller the principal who is invoking this method. + * @param name the name of the ACL. + * @exception NotOwnerException if the caller principal is + * not on the owners list of the Acl. + */ + public void setName(Principal caller, String name) + throws NotOwnerException { + if (!isOwner(caller)) + throw new NotOwnerException(); + + aclName = name; + } + + /** + * Returns the name of the ACL. + * + * @return the name of the ACL. + */ + public String getName() { + return aclName; + } + + /** + * Adds an ACL entry to this ACL. An entry associates a + * group or a principal with a set of permissions. Each + * user or group can have one positive ACL entry and one + * negative ACL entry. If there is one of the type (negative + * or positive) already in the table, a false value is returned. + * The caller principal must be a part of the owners list of + * the ACL in order to invoke this method. + * + * @param caller the principal who is invoking this method. + * @param entry the ACL entry that must be added to the ACL. + * @return true on success, false if the entry is already present. + * @exception NotOwnerException if the caller principal + * is not on the owners list of the Acl. + */ + public synchronized boolean addEntry(Principal caller, AclEntry entry) + throws NotOwnerException { + if (!isOwner(caller)) + throw new NotOwnerException(); + + Hashtable<Principal, AclEntry> aclTable = findTable(entry); + Principal key = entry.getPrincipal(); + + if (aclTable.get(key) != null) + return false; + + aclTable.put(key, entry); + return true; + } + + /** + * Removes an ACL entry from this ACL. + * The caller principal must be a part of the owners list of the ACL + * in order to invoke this method. + * + * @param caller the principal who is invoking this method. + * @param entry the ACL entry that must be removed from the ACL. + * @return true on success, false if the entry is not part of the ACL. + * @exception NotOwnerException if the caller principal is not + * the owners list of the Acl. + */ + public synchronized boolean removeEntry(Principal caller, AclEntry entry) + throws NotOwnerException { + if (!isOwner(caller)) + throw new NotOwnerException(); + + Hashtable<Principal, AclEntry> aclTable = findTable(entry); + Object key = entry.getPrincipal(); + + Object o = aclTable.remove(key); + return (o != null); + } + + /** + * This method returns the set of allowed permissions for the + * specified principal. This set of allowed permissions is calculated + * as follows: + * + * If there is no entry for a group or a principal an empty permission + * set is assumed. + * + * The group positive permission set is the union of all + * the positive permissions of each group that the individual belongs to. + * The group negative permission set is the union of all + * the negative permissions of each group that the individual belongs to. + * If there is a specific permission that occurs in both + * the postive permission set and the negative permission set, + * it is removed from both. The group positive and negatoive permission + * sets are calculated. + * + * The individial positive permission set and the individual negative + * permission set is then calculated. Again abscence of an entry means + * the empty set. + * + * The set of permissions granted to the principal is then calculated using + * the simple rule: Individual permissions always override the Group permissions. + * Specifically, individual negative permission set (specific + * denial of permissions) overrides the group positive permission set. + * And the individual positive permission set override the group negative + * permission set. + * + * @param user the principal for which the ACL entry is returned. + * @return The resulting permission set that the principal is allowed. + */ + public synchronized Enumeration<Permission> getPermissions(Principal user) { + + Enumeration<Permission> individualPositive; + Enumeration<Permission> individualNegative; + Enumeration<Permission> groupPositive; + Enumeration<Permission> groupNegative; + + // + // canonicalize the sets. That is remove common permissions from + // positive and negative sets. + // + groupPositive = subtract(getGroupPositive(user), getGroupNegative(user)); + groupNegative = subtract(getGroupNegative(user), getGroupPositive(user)); + individualPositive = subtract(getIndividualPositive(user), getIndividualNegative(user)); + individualNegative = subtract(getIndividualNegative(user), getIndividualPositive(user)); + + // + // net positive permissions is individual positive permissions + // plus (group positive - individual negative). + // + Enumeration<Permission> temp1 = subtract(groupPositive, individualNegative); + Enumeration<Permission> netPositive = union(individualPositive, temp1); + + // recalculate the enumeration since we lost it in performing the + // subtraction + // + individualPositive = subtract(getIndividualPositive(user), getIndividualNegative(user)); + individualNegative = subtract(getIndividualNegative(user), getIndividualPositive(user)); + + // + // net negative permissions is individual negative permissions + // plus (group negative - individual positive). + // + temp1 = subtract(groupNegative, individualPositive); + Enumeration<Permission> netNegative = union(individualNegative, temp1); + + return subtract(netPositive, netNegative); + } + + /** + * This method checks whether or not the specified principal + * has the required permission. If permission is denied + * permission false is returned, a true value is returned otherwise. + * This method does not authenticate the principal. It presumes that + * the principal is a valid authenticated principal. + * + * @param principal the name of the authenticated principal + * @param permission the permission that the principal must have. + * @return true of the principal has the permission desired, false + * otherwise. + */ + public boolean checkPermission(Principal principal, Permission permission) { + Enumeration<Permission> permSet = getPermissions(principal); + while (permSet.hasMoreElements()) { + Permission p = (Permission) permSet.nextElement(); + if (p.equals(permission)) + return true; + } + return false; + } + + /** + * returns an enumeration of the entries in this ACL. + */ + public synchronized Enumeration<AclEntry> entries() { + return new AclEnumerator(this, + allowedUsersTable, allowedGroupsTable, + deniedUsersTable, deniedGroupsTable); + } + + /** + * return a stringified version of the + * ACL. + */ + public String toString() { + StringBuffer sb = new StringBuffer(); + Enumeration<AclEntry> entries = entries(); + while (entries.hasMoreElements()) { + AclEntry entry = (AclEntry) entries.nextElement(); + sb.append(entry.toString().trim()); + sb.append("\n"); + } + + return sb.toString(); + } + + // + // Find the table that this entry belongs to. There are 4 + // tables that are maintained. One each for postive and + // negative ACLs and one each for groups and users. + // This method figures out which + // table is the one that this AclEntry belongs to. + // + private Hashtable<Principal, AclEntry> findTable(AclEntry entry) { + Hashtable<Principal, AclEntry> aclTable = null; + + Principal p = entry.getPrincipal(); + if (p instanceof Group) { + if (entry.isNegative()) + aclTable = deniedGroupsTable; + else + aclTable = allowedGroupsTable; + } else { + if (entry.isNegative()) + aclTable = deniedUsersTable; + else + aclTable = allowedUsersTable; + } + return aclTable; + } + + // + // returns the set e1 U e2. + // + private <T> Enumeration<T> union(Enumeration<T> e1, Enumeration<T> e2) { + Vector<T> v = new Vector<T>(20, 20); + + while (e1.hasMoreElements()) + v.addElement(e1.nextElement()); + + while (e2.hasMoreElements()) { + T o = e2.nextElement(); + if (!v.contains(o)) + v.addElement(o); + } + + return v.elements(); + } + + // + // returns the set e1 - e2. + // + private <T> Enumeration<T> subtract(Enumeration<T> e1, Enumeration<T> e2) { + Vector<T> v = new Vector<T>(20, 20); + + while (e1.hasMoreElements()) + v.addElement(e1.nextElement()); + + while (e2.hasMoreElements()) { + T o = e2.nextElement(); + if (v.contains(o)) + v.removeElement(o); + } + + return v.elements(); + } + + private Enumeration<Permission> getGroupPositive(Principal user) { + Enumeration<Permission> groupPositive = zeroSet.elements(); + Enumeration<Principal> e = allowedGroupsTable.keys(); + while (e.hasMoreElements()) { + Group g = (Group) e.nextElement(); + if (g.isMember(user)) { + AclEntry ae = (AclEntry) allowedGroupsTable.get(g); + groupPositive = union(ae.permissions(), groupPositive); + } + } + return groupPositive; + } + + private Enumeration<Permission> getGroupNegative(Principal user) { + Enumeration<Permission> groupNegative = zeroSet.elements(); + Enumeration<Principal> e = deniedGroupsTable.keys(); + while (e.hasMoreElements()) { + Group g = (Group) e.nextElement(); + if (g.isMember(user)) { + AclEntry ae = (AclEntry) deniedGroupsTable.get(g); + groupNegative = union(ae.permissions(), groupNegative); + } + } + return groupNegative; + } + + private Enumeration<Permission> getIndividualPositive(Principal user) { + Enumeration<Permission> individualPositive = zeroSet.elements(); + AclEntry ae = (AclEntry) allowedUsersTable.get(user); + if (ae != null) + individualPositive = ae.permissions(); + return individualPositive; + } + + private Enumeration<Permission> getIndividualNegative(Principal user) { + Enumeration<Permission> individualNegative = zeroSet.elements(); + AclEntry ae = (AclEntry) deniedUsersTable.get(user); + if (ae != null) + individualNegative = ae.permissions(); + return individualNegative; + } +} + +final class AclEnumerator implements Enumeration<AclEntry> { + Acl acl; + Enumeration<AclEntry> u1, u2, g1, g2; + + AclEnumerator(Acl acl, Hashtable<Principal, AclEntry> u1, Hashtable<Principal, AclEntry> g1, + Hashtable<Principal, AclEntry> u2, Hashtable<Principal, AclEntry> g2) { + this.acl = acl; + this.u1 = u1.elements(); + this.u2 = u2.elements(); + this.g1 = g1.elements(); + this.g2 = g2.elements(); + } + + public boolean hasMoreElements() { + return (u1.hasMoreElements() || + u2.hasMoreElements() || + g1.hasMoreElements() || g2.hasMoreElements()); + } + + public AclEntry nextElement() { + synchronized (acl) { + if (u1.hasMoreElements()) + return u1.nextElement(); + if (u2.hasMoreElements()) + return u2.nextElement(); + if (g1.hasMoreElements()) + return g1.nextElement(); + if (g2.hasMoreElements()) + return g2.nextElement(); + } + throw new NoSuchElementException("Acl Enumerator"); + } +} |