--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/security/AccessControlContext.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,574 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.security;
+
+import java.util.ArrayList;
+import java.util.List;
+import sun.security.util.Debug;
+import sun.security.util.SecurityConstants;
+
+/**
+ * An AccessControlContext is used to make system resource access decisions
+ * based on the context it encapsulates.
+ *
+ * <p>More specifically, it encapsulates a context and
+ * has a single method, <code>checkPermission</code>,
+ * that is equivalent to the <code>checkPermission</code> method
+ * in the AccessController class, with one difference: The AccessControlContext
+ * <code>checkPermission</code> method makes access decisions based on the
+ * context it encapsulates,
+ * rather than that of the current execution thread.
+ *
+ * <p>Thus, the purpose of AccessControlContext is for those situations where
+ * a security check that should be made within a given context
+ * actually needs to be done from within a
+ * <i>different</i> context (for example, from within a worker thread).
+ *
+ * <p> An AccessControlContext is created by calling the
+ * <code>AccessController.getContext</code> method.
+ * The <code>getContext</code> method takes a "snapshot"
+ * of the current calling context, and places
+ * it in an AccessControlContext object, which it returns. A sample call is
+ * the following:
+ *
+ * <pre>
+ * AccessControlContext acc = AccessController.getContext()
+ * </pre>
+ *
+ * <p>
+ * Code within a different context can subsequently call the
+ * <code>checkPermission</code> method on the
+ * previously-saved AccessControlContext object. A sample call is the
+ * following:
+ *
+ * <pre>
+ * acc.checkPermission(permission)
+ * </pre>
+ *
+ * @see AccessController
+ *
+ * @author Roland Schemers
+ */
+
+public final class AccessControlContext {
+
+ private ProtectionDomain context[];
+ private boolean isPrivileged;
+
+ // Note: This field is directly used by the virtual machine
+ // native codes. Don't touch it.
+ private AccessControlContext privilegedContext;
+
+ private DomainCombiner combiner = null;
+
+ private static boolean debugInit = false;
+ private static Debug debug = null;
+
+ static Debug getDebug()
+ {
+ if (debugInit)
+ return debug;
+ else {
+ if (Policy.isSet()) {
+ debug = Debug.getInstance("access");
+ debugInit = true;
+ }
+ return debug;
+ }
+ }
+
+ /**
+ * Create an AccessControlContext with the given set of ProtectionDomains.
+ * Context must not be null. Duplicate domains will be removed from the
+ * context.
+ *
+ * @param context the ProtectionDomains associated with this context.
+ * The non-duplicate domains are copied from the array. Subsequent
+ * changes to the array will not affect this AccessControlContext.
+ */
+ public AccessControlContext(ProtectionDomain context[])
+ {
+ if (context.length == 0) {
+ this.context = null;
+ } else if (context.length == 1) {
+ if (context[0] != null) {
+ this.context = context.clone();
+ } else {
+ this.context = null;
+ }
+ } else {
+ List<ProtectionDomain> v = new ArrayList<ProtectionDomain>(context.length);
+ for (int i =0; i< context.length; i++) {
+ if ((context[i] != null) && (!v.contains(context[i])))
+ v.add(context[i]);
+ }
+ this.context = new ProtectionDomain[v.size()];
+ this.context = v.toArray(this.context);
+ }
+ }
+
+ /**
+ * Create a new <code>AccessControlContext</code> with the given
+ * <code>AccessControlContext</code> and <code>DomainCombiner</code>.
+ * This constructor associates the provided
+ * <code>DomainCombiner</code> with the provided
+ * <code>AccessControlContext</code>.
+ *
+ * <p>
+ *
+ * @param acc the <code>AccessControlContext</code> associated
+ * with the provided <code>DomainCombiner</code>.
+ *
+ * @param combiner the <code>DomainCombiner</code> to be associated
+ * with the provided <code>AccessControlContext</code>.
+ *
+ * @exception NullPointerException if the provided
+ * <code>context</code> is <code>null</code>.
+ *
+ * @exception SecurityException if a security manager is installed and the
+ * caller does not have the "createAccessControlContext"
+ * {@link SecurityPermission}
+ * @since 1.3
+ */
+ public AccessControlContext(AccessControlContext acc,
+ DomainCombiner combiner) {
+
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ sm.checkPermission(SecurityConstants.CREATE_ACC_PERMISSION);
+ }
+
+ this.context = acc.context;
+
+ // we do not need to run the combine method on the
+ // provided ACC. it was already "combined" when the
+ // context was originally retrieved.
+ //
+ // at this point in time, we simply throw away the old
+ // combiner and use the newly provided one.
+ this.combiner = combiner;
+ }
+
+ /**
+ * package private for AccessController
+ */
+ AccessControlContext(ProtectionDomain context[], DomainCombiner combiner) {
+ if (context != null) {
+ this.context = context.clone();
+ }
+ this.combiner = combiner;
+ }
+
+ /**
+ * package private constructor for AccessController.getContext()
+ */
+
+ AccessControlContext(ProtectionDomain context[],
+ boolean isPrivileged)
+ {
+ this.context = context;
+ this.isPrivileged = isPrivileged;
+ }
+
+ /**
+ * Returns true if this context is privileged.
+ */
+ boolean isPrivileged()
+ {
+ return isPrivileged;
+ }
+
+ /**
+ * get the assigned combiner from the privileged or inherited context
+ */
+ DomainCombiner getAssignedCombiner() {
+ AccessControlContext acc;
+ if (isPrivileged) {
+ acc = privilegedContext;
+ } else {
+ acc = AccessController.getInheritedAccessControlContext();
+ }
+ if (acc != null) {
+ return acc.combiner;
+ }
+ return null;
+ }
+
+ /**
+ * Get the <code>DomainCombiner</code> associated with this
+ * <code>AccessControlContext</code>.
+ *
+ * <p>
+ *
+ * @return the <code>DomainCombiner</code> associated with this
+ * <code>AccessControlContext</code>, or <code>null</code>
+ * if there is none.
+ *
+ * @exception SecurityException if a security manager is installed and
+ * the caller does not have the "getDomainCombiner"
+ * {@link SecurityPermission}
+ * @since 1.3
+ */
+ public DomainCombiner getDomainCombiner() {
+
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ sm.checkPermission(SecurityConstants.GET_COMBINER_PERMISSION);
+ }
+ return combiner;
+ }
+
+ /**
+ * Determines whether the access request indicated by the
+ * specified permission should be allowed or denied, based on
+ * the security policy currently in effect, and the context in
+ * this object. The request is allowed only if every ProtectionDomain
+ * in the context implies the permission. Otherwise the request is
+ * denied.
+ *
+ * <p>
+ * This method quietly returns if the access request
+ * is permitted, or throws a suitable AccessControlException otherwise.
+ *
+ * @param perm the requested permission.
+ *
+ * @exception AccessControlException if the specified permission
+ * is not permitted, based on the current security policy and the
+ * context encapsulated by this object.
+ * @exception NullPointerException if the permission to check for is null.
+ */
+ public void checkPermission(Permission perm)
+ throws AccessControlException
+ {
+ boolean dumpDebug = false;
+
+ if (perm == null) {
+ throw new NullPointerException("permission can't be null");
+ }
+ if (getDebug() != null) {
+ // If "codebase" is not specified, we dump the info by default.
+ dumpDebug = !Debug.isOn("codebase=");
+ if (!dumpDebug) {
+ // If "codebase" is specified, only dump if the specified code
+ // value is in the stack.
+ for (int i = 0; context != null && i < context.length; i++) {
+ if (context[i].getCodeSource() != null &&
+ context[i].getCodeSource().getLocation() != null &&
+ Debug.isOn("codebase=" + context[i].getCodeSource().getLocation().toString())) {
+ dumpDebug = true;
+ break;
+ }
+ }
+ }
+
+ dumpDebug &= !Debug.isOn("permission=") ||
+ Debug.isOn("permission=" + perm.getClass().getCanonicalName());
+
+ if (dumpDebug && Debug.isOn("stack")) {
+ Thread.currentThread().dumpStack();
+ }
+
+ if (dumpDebug && Debug.isOn("domain")) {
+ if (context == null) {
+ debug.println("domain (context is null)");
+ } else {
+ for (int i=0; i< context.length; i++) {
+ debug.println("domain "+i+" "+context[i]);
+ }
+ }
+ }
+ }
+
+ /*
+ * iterate through the ProtectionDomains in the context.
+ * Stop at the first one that doesn't allow the
+ * requested permission (throwing an exception).
+ *
+ */
+
+ /* if ctxt is null, all we had on the stack were system domains,
+ or the first domain was a Privileged system domain. This
+ is to make the common case for system code very fast */
+
+ if (context == null)
+ return;
+
+ for (int i=0; i< context.length; i++) {
+ if (context[i] != null && !context[i].implies(perm)) {
+ if (dumpDebug) {
+ debug.println("access denied " + perm);
+ }
+
+ if (Debug.isOn("failure")) {
+ // Want to make sure this is always displayed for failure,
+ // but do not want to display again if already displayed
+ // above.
+ if (!dumpDebug) {
+ debug.println("access denied " + perm);
+ }
+ Thread.currentThread().dumpStack();
+ final ProtectionDomain pd = context[i];
+ final Debug db = debug;
+ AccessController.doPrivileged (new PrivilegedAction<Void>() {
+ public Void run() {
+ db.println("domain that failed "+pd);
+ return null;
+ }
+ });
+ }
+ throw new AccessControlException("access denied "+perm, perm);
+ }
+ }
+
+ // allow if all of them allowed access
+ if (dumpDebug) {
+ debug.println("access allowed "+perm);
+ }
+
+ return;
+ }
+
+ /**
+ * Take the stack-based context (this) and combine it with the
+ * privileged or inherited context, if need be.
+ */
+ AccessControlContext optimize() {
+ // the assigned (privileged or inherited) context
+ AccessControlContext acc;
+ if (isPrivileged) {
+ acc = privilegedContext;
+ } else {
+ acc = AccessController.getInheritedAccessControlContext();
+ }
+
+ // this.context could be null if only system code is on the stack;
+ // in that case, ignore the stack context
+ boolean skipStack = (context == null);
+
+ // acc.context could be null if only system code was involved;
+ // in that case, ignore the assigned context
+ boolean skipAssigned = (acc == null || acc.context == null);
+
+ if (acc != null && acc.combiner != null) {
+ // let the assigned acc's combiner do its thing
+ return goCombiner(context, acc);
+ }
+
+ // optimization: if neither have contexts; return acc if possible
+ // rather than this, because acc might have a combiner
+ if (skipAssigned && skipStack) {
+ return this;
+ }
+
+ // optimization: if there is no stack context; there is no reason
+ // to compress the assigned context, it already is compressed
+ if (skipStack) {
+ return acc;
+ }
+
+ int slen = context.length;
+
+ // optimization: if there is no assigned context and the stack length
+ // is less then or equal to two; there is no reason to compress the
+ // stack context, it already is
+ if (skipAssigned && slen <= 2) {
+ return this;
+ }
+
+ // optimization: if there is a single stack domain and that domain
+ // is already in the assigned context; no need to combine
+ if ((slen == 1) && (context[0] == acc.context[0])) {
+ return acc;
+ }
+
+ int n = (skipAssigned) ? 0 : acc.context.length;
+
+ // now we combine both of them, and create a new context
+ ProtectionDomain pd[] = new ProtectionDomain[slen + n];
+
+ // first copy in the assigned context domains, no need to compress
+ if (!skipAssigned) {
+ System.arraycopy(acc.context, 0, pd, 0, n);
+ }
+
+ // now add the stack context domains, discarding nulls and duplicates
+ outer:
+ for (int i = 0; i < context.length; i++) {
+ ProtectionDomain sd = context[i];
+ if (sd != null) {
+ for (int j = 0; j < n; j++) {
+ if (sd == pd[j]) {
+ continue outer;
+ }
+ }
+ pd[n++] = sd;
+ }
+ }
+
+ // if length isn't equal, we need to shorten the array
+ if (n != pd.length) {
+ // optimization: if we didn't really combine anything
+ if (!skipAssigned && n == acc.context.length) {
+ return acc;
+ } else if (skipAssigned && n == slen) {
+ return this;
+ }
+ ProtectionDomain tmp[] = new ProtectionDomain[n];
+ System.arraycopy(pd, 0, tmp, 0, n);
+ pd = tmp;
+ }
+
+ // return new AccessControlContext(pd, false);
+
+ // Reuse existing ACC
+
+ this.context = pd;
+ this.combiner = null;
+ this.isPrivileged = false;
+
+ return this;
+ }
+
+ private AccessControlContext goCombiner(ProtectionDomain[] current,
+ AccessControlContext assigned) {
+
+ // the assigned ACC's combiner is not null --
+ // let the combiner do its thing
+
+ // XXX we could add optimizations to 'current' here ...
+
+ if (getDebug() != null) {
+ debug.println("AccessControlContext invoking the Combiner");
+ }
+
+ // No need to clone current and assigned.context
+ // combine() will not update them
+ ProtectionDomain[] combinedPds = assigned.combiner.combine(
+ current, assigned.context);
+
+ // return new AccessControlContext(combinedPds, assigned.combiner);
+
+ // Reuse existing ACC
+ this.context = combinedPds;
+ this.combiner = assigned.combiner;
+ this.isPrivileged = false;
+
+ return this;
+ }
+
+ /**
+ * Checks two AccessControlContext objects for equality.
+ * Checks that <i>obj</i> is
+ * an AccessControlContext and has the same set of ProtectionDomains
+ * as this context.
+ * <P>
+ * @param obj the object we are testing for equality with this object.
+ * @return true if <i>obj</i> is an AccessControlContext, and has the
+ * same set of ProtectionDomains as this context, false otherwise.
+ */
+ public boolean equals(Object obj) {
+ if (obj == this)
+ return true;
+
+ if (! (obj instanceof AccessControlContext))
+ return false;
+
+ AccessControlContext that = (AccessControlContext) obj;
+
+
+ if (context == null) {
+ return (that.context == null);
+ }
+
+ if (that.context == null)
+ return false;
+
+ if (!(this.containsAllPDs(that) && that.containsAllPDs(this)))
+ return false;
+
+ if (this.combiner == null)
+ return (that.combiner == null);
+
+ if (that.combiner == null)
+ return false;
+
+ if (!this.combiner.equals(that.combiner))
+ return false;
+
+ return true;
+ }
+
+ private boolean containsAllPDs(AccessControlContext that) {
+ boolean match = false;
+ //
+ // ProtectionDomains within an ACC currently cannot be null
+ // and this is enforced by the constructor and the various
+ // optimize methods. However, historically this logic made attempts
+ // to support the notion of a null PD and therefore this logic continues
+ // to support that notion.
+ ProtectionDomain thisPd;
+ for (int i = 0; i < context.length; i++) {
+ match = false;
+ if ((thisPd = context[i]) == null) {
+ for (int j = 0; (j < that.context.length) && !match; j++) {
+ match = (that.context[j] == null);
+ }
+ } else {
+ Class thisPdClass = thisPd.getClass();
+ ProtectionDomain thatPd;
+ for (int j = 0; (j < that.context.length) && !match; j++) {
+ thatPd = that.context[j];
+
+ // Class check required to avoid PD exposure (4285406)
+ match = (thatPd != null &&
+ thisPdClass == thatPd.getClass() && thisPd.equals(thatPd));
+ }
+ }
+ if (!match) return false;
+ }
+ return match;
+ }
+ /**
+ * Returns the hash code value for this context. The hash code
+ * is computed by exclusive or-ing the hash code of all the protection
+ * domains in the context together.
+ *
+ * @return a hash code value for this context.
+ */
+
+ public int hashCode() {
+ int hashCode = 0;
+
+ if (context == null)
+ return hashCode;
+
+ for (int i =0; i < context.length; i++) {
+ if (context[i] != null)
+ hashCode ^= context[i].hashCode();
+ }
+ return hashCode;
+ }
+}