1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.security;
27
28 import java.util.ArrayList;
29 import java.util.List;
30
31 import sun.security.util.Debug;
32 import sun.security.util.FilePermCompat;
33 import sun.security.util.SecurityConstants;
34
35
36 /**
37 * An AccessControlContext is used to make system resource access decisions
38 * based on the context it encapsulates.
39 *
40 * <p>More specifically, it encapsulates a context and
41 * has a single method, {@code checkPermission},
42 * that is equivalent to the {@code checkPermission} method
43 * in the AccessController class, with one difference: The AccessControlContext
44 * {@code checkPermission} method makes access decisions based on the
45 * context it encapsulates,
46 * rather than that of the current execution thread.
47 *
48 * <p>Thus, the purpose of AccessControlContext is for those situations where
49 * a security check that should be made within a given context
50 * actually needs to be done from within a
51 * <i>different</i> context (for example, from within a worker thread).
52 *
53 * <p> An AccessControlContext is created by calling the
54 * {@code AccessController.getContext} method.
55 * The {@code getContext} method takes a "snapshot"
56 * of the current calling context, and places
57 * it in an AccessControlContext object, which it returns. A sample call is
58 * the following:
59 *
60 * <pre>
61 * AccessControlContext acc = AccessController.getContext()
62 * </pre>
63 *
64 * <p>
65 * Code within a different context can subsequently call the
66 * {@code checkPermission} method on the
67 * previously-saved AccessControlContext object. A sample call is the
68 * following:
69 *
70 * <pre>
71 * acc.checkPermission(permission)
72 * </pre>
73 *
74 * @see AccessController
75 *
76 * @author Roland Schemers
77 */
78
79 public final class AccessControlContext {
80
81 private ProtectionDomain[] context;
82 // isPrivileged and isAuthorized are referenced by the VM - do not remove
83 // or change their names
84 private boolean isPrivileged;
85 private boolean isAuthorized = false;
86
87 // Note: This field is directly used by the virtual machine
88 // native codes. Don't touch it.
89 private AccessControlContext privilegedContext;
90
91 private DomainCombiner combiner = null;
92
93 // limited privilege scope
94 private Permission[] permissions;
95 private AccessControlContext parent;
96 private boolean isWrapped;
97
98 // is constrained by limited privilege scope?
99 private boolean isLimited;
100 private ProtectionDomain[] limitedContext;
101
102 private static boolean debugInit = false;
103 private static Debug debug = null;
104
105 static Debug getDebug()
106 {
107 if (debugInit)
108 return debug;
109 else {
110 if (Policy.isSet()) {
111 debug = Debug.getInstance("access");
112 debugInit = true;
113 }
114 return debug;
115 }
116 }
117
118 /**
119 * Create an AccessControlContext with the given array of ProtectionDomains.
120 * Context must not be null. Duplicate domains will be removed from the
121 * context.
122 *
123 * @param context the ProtectionDomains associated with this context.
124 * The non-duplicate domains are copied from the array. Subsequent
125 * changes to the array will not affect this AccessControlContext.
126 * @throws NullPointerException if {@code context} is {@code null}
127 */
128 public AccessControlContext(ProtectionDomain[] context)
129 {
130 if (context.length == 0) {
131 this.context = null;
132 } else if (context.length == 1) {
133 if (context[0] != null) {
134 this.context = context.clone();
135 } else {
136 this.context = null;
137 }
138 } else {
139 List<ProtectionDomain> v = new ArrayList<>(context.length);
140 for (int i =0; i< context.length; i++) {
141 if ((context[i] != null) && (!v.contains(context[i])))
142 v.add(context[i]);
143 }
144 if (!v.isEmpty()) {
145 this.context = new ProtectionDomain[v.size()];
146 this.context = v.toArray(this.context);
147 }
148 }
149 }
150
151 /**
152 * Create a new {@code AccessControlContext} with the given
153 * {@code AccessControlContext} and {@code DomainCombiner}.
154 * This constructor associates the provided
155 * {@code DomainCombiner} with the provided
156 * {@code AccessControlContext}.
157 *
158 * @param acc the {@code AccessControlContext} associated
159 * with the provided {@code DomainCombiner}.
160 *
161 * @param combiner the {@code DomainCombiner} to be associated
162 * with the provided {@code AccessControlContext}.
163 *
164 * @exception NullPointerException if the provided
165 * {@code context} is {@code null}.
166 *
167 * @exception SecurityException if a security manager is installed and the
168 * caller does not have the "createAccessControlContext"
169 * {@link SecurityPermission}
170 * @since 1.3
171 */
172 public AccessControlContext(AccessControlContext acc,
173 DomainCombiner combiner) {
174
175 this(acc, combiner, false);
176 }
177
178 /**
179 * package private to allow calls from ProtectionDomain without performing
180 * the security check for {@linkplain SecurityConstants#CREATE_ACC_PERMISSION}
181 * permission
182 */
183 AccessControlContext(AccessControlContext acc,
184 DomainCombiner combiner,
185 boolean preauthorized) {
186 if (!preauthorized) {
187 SecurityManager sm = System.getSecurityManager();
188 if (sm != null) {
189 sm.checkPermission(SecurityConstants.CREATE_ACC_PERMISSION);
190 this.isAuthorized = true;
191 }
192 } else {
193 this.isAuthorized = true;
194 }
195
196 this.context = acc.context;
197
198 // we do not need to run the combine method on the
199 // provided ACC. it was already "combined" when the
200 // context was originally retrieved.
201 //
202 // at this point in time, we simply throw away the old
203 // combiner and use the newly provided one.
204 this.combiner = combiner;
205 }
206
207 /**
208 * package private for AccessController
209 *
210 * This "argument wrapper" context will be passed as the actual context
211 * parameter on an internal doPrivileged() call used in the implementation.
212 */
213 AccessControlContext(ProtectionDomain caller, DomainCombiner combiner,
214 AccessControlContext parent, AccessControlContext context,
215 Permission[] perms)
216 {
217 /*
218 * Combine the domains from the doPrivileged() context into our
219 * wrapper context, if necessary.
220 */
221 ProtectionDomain[] callerPDs = null;
222 if (caller != null) {
223 callerPDs = new ProtectionDomain[] { caller };
224 }
225 if (context != null) {
226 if (combiner != null) {
227 this.context = combiner.combine(callerPDs, context.context);
228 } else {
229 this.context = combine(callerPDs, context.context);
230 }
231 } else {
232 /*
233 * Call combiner even if there is seemingly nothing to combine.
234 */
235 if (combiner != null) {
236 this.context = combiner.combine(callerPDs, null);
237 } else {
238 this.context = combine(callerPDs, null);
239 }
240 }
241 this.combiner = combiner;
242
243 Permission[] tmp = null;
244 if (perms != null) {
245 tmp = new Permission[perms.length];
246 for (int i=0; i < perms.length; i++) {
247 if (perms[i] == null) {
248 throw new NullPointerException("permission can't be null");
249 }
250
251 /*
252 * An AllPermission argument is equivalent to calling
253 * doPrivileged() without any limit permissions.
254 */
255 if (perms[i].getClass() == AllPermission.class) {
256 parent = null;
257 }
258 // Add altPath into permission for compatibility.
259 tmp[i] = FilePermCompat.newPermPlusAltPath(perms[i]);
260 }
261 }
262
263 /*
264 * For a doPrivileged() with limited privilege scope, initialize
265 * the relevant fields.
266 *
267 * The limitedContext field contains the union of all domains which
268 * are enclosed by this limited privilege scope. In other words,
269 * it contains all of the domains which could potentially be checked
270 * if none of the limiting permissions implied a requested permission.
271 */
272 if (parent != null) {
273 this.limitedContext = combine(parent.context, parent.limitedContext);
274 this.isLimited = true;
275 this.isWrapped = true;
276 this.permissions = tmp;
277 this.parent = parent;
278 this.privilegedContext = context; // used in checkPermission2()
279 }
280 this.isAuthorized = true;
281 }
282
283
284 /**
285 * package private constructor for AccessController.getContext()
286 */
287
288 AccessControlContext(ProtectionDomain[] context,
289 boolean isPrivileged)
290 {
291 this.context = context;
292 this.isPrivileged = isPrivileged;
293 this.isAuthorized = true;
294 }
295
296 /**
297 * Constructor for JavaSecurityAccess.doIntersectionPrivilege()
298 */
299 AccessControlContext(ProtectionDomain[] context,
300 AccessControlContext privilegedContext)
301 {
302 this.context = context;
303 this.privilegedContext = privilegedContext;
304 this.isPrivileged = true;
305 }
306
307 /**
308 * Returns this context's context.
309 */
310 ProtectionDomain[] getContext() {
311 return context;
312 }
313
314 /**
315 * Returns true if this context is privileged.
316 */
317 boolean isPrivileged()
318 {
319 return isPrivileged;
320 }
321
322 /**
323 * get the assigned combiner from the privileged or inherited context
324 */
325 DomainCombiner getAssignedCombiner() {
326 AccessControlContext acc;
327 if (isPrivileged) {
328 acc = privilegedContext;
329 } else {
330 acc = AccessController.getInheritedAccessControlContext();
331 }
332 if (acc != null) {
333 return acc.combiner;
334 }
335 return null;
336 }
337
338 /**
339 * Get the {@code DomainCombiner} associated with this
340 * {@code AccessControlContext}.
341 *
342 * @return the {@code DomainCombiner} associated with this
343 * {@code AccessControlContext}, or {@code null}
344 * if there is none.
345 *
346 * @exception SecurityException if a security manager is installed and
347 * the caller does not have the "getDomainCombiner"
348 * {@link SecurityPermission}
349 * @since 1.3
350 */
351 public DomainCombiner getDomainCombiner() {
352
353 SecurityManager sm = System.getSecurityManager();
354 if (sm != null) {
355 sm.checkPermission(SecurityConstants.GET_COMBINER_PERMISSION);
356 }
357 return getCombiner();
358 }
359
360 /**
361 * package private for AccessController
362 */
363 DomainCombiner getCombiner() {
364 return combiner;
365 }
366
367 boolean isAuthorized() {
368 return isAuthorized;
369 }
370
371 /**
372 * Determines whether the access request indicated by the
373 * specified permission should be allowed or denied, based on
374 * the security policy currently in effect, and the context in
375 * this object. The request is allowed only if every ProtectionDomain
376 * in the context implies the permission. Otherwise the request is
377 * denied.
378 *
379 * <p>
380 * This method quietly returns if the access request
381 * is permitted, or throws a suitable AccessControlException otherwise.
382 *
383 * @param perm the requested permission.
384 *
385 * @exception AccessControlException if the specified permission
386 * is not permitted, based on the current security policy and the
387 * context encapsulated by this object.
388 * @exception NullPointerException if the permission to check for is null.
389 */
390 public void checkPermission(Permission perm)
391 throws AccessControlException
392 {
393 boolean dumpDebug = false;
394
395 if (perm == null) {
396 throw new NullPointerException("permission can't be null");
397 }
398 if (getDebug() != null) {
399 // If "codebase" is not specified, we dump the info by default.
400 dumpDebug = !Debug.isOn("codebase=");
401 if (!dumpDebug) {
402 // If "codebase" is specified, only dump if the specified code
403 // value is in the stack.
404 for (int i = 0; context != null && i < context.length; i++) {
405 if (context[i].getCodeSource() != null &&
406 context[i].getCodeSource().getLocation() != null &&
407 Debug.isOn("codebase=" + context[i].getCodeSource().getLocation().toString())) {
408 dumpDebug = true;
409 break;
410 }
411 }
412 }
413
414 dumpDebug &= !Debug.isOn("permission=") ||
415 Debug.isOn("permission=" + perm.getClass().getCanonicalName());
416
417 if (dumpDebug && Debug.isOn("stack")) {
418 Thread.dumpStack();
419 }
420
421 if (dumpDebug && Debug.isOn("domain")) {
422 if (context == null) {
423 debug.println("domain (context is null)");
424 } else {
425 for (int i=0; i< context.length; i++) {
426 debug.println("domain "+i+" "+context[i]);
427 }
428 }
429 }
430 }
431
432 /*
433 * iterate through the ProtectionDomains in the context.
434 * Stop at the first one that doesn't allow the
435 * requested permission (throwing an exception).
436 *
437 */
438
439 /* if ctxt is null, all we had on the stack were system domains,
440 or the first domain was a Privileged system domain. This
441 is to make the common case for system code very fast */
442
443 if (context == null) {
444 checkPermission2(perm);
445 return;
446 }
447
448 for (int i=0; i< context.length; i++) {
449 if (context[i] != null && !context[i].impliesWithAltFilePerm(perm)) {
450 if (dumpDebug) {
451 debug.println("access denied " + perm);
452 }
453
454 if (Debug.isOn("failure") && debug != null) {
455 // Want to make sure this is always displayed for failure,
456 // but do not want to display again if already displayed
457 // above.
458 if (!dumpDebug) {
459 debug.println("access denied " + perm);
460 }
461 Thread.dumpStack();
462 final ProtectionDomain pd = context[i];
463 final Debug db = debug;
464 AccessController.doPrivileged (new PrivilegedAction<>() {
465 public Void run() {
466 db.println("domain that failed "+pd);
467 return null;
468 }
469 });
470 }
471 throw new AccessControlException("access denied "+perm, perm);
472 }
473 }
474
475 // allow if all of them allowed access
476 if (dumpDebug) {
477 debug.println("access allowed "+perm);
478 }
479
480 checkPermission2(perm);
481 }
482
483 /*
484 * Check the domains associated with the limited privilege scope.
485 */
486 private void checkPermission2(Permission perm) {
487 if (!isLimited) {
488 return;
489 }
490
491 /*
492 * Check the doPrivileged() context parameter, if present.
493 */
494 if (privilegedContext != null) {
495 privilegedContext.checkPermission2(perm);
496 }
497
498 /*
499 * Ignore the limited permissions and parent fields of a wrapper
500 * context since they were already carried down into the unwrapped
501 * context.
502 */
503 if (isWrapped) {
504 return;
505 }
506
507 /*
508 * Try to match any limited privilege scope.
509 */
510 if (permissions != null) {
511 Class<?> permClass = perm.getClass();
512 for (int i=0; i < permissions.length; i++) {
513 Permission limit = permissions[i];
514 if (limit.getClass().equals(permClass) && limit.implies(perm)) {
515 return;
516 }
517 }
518 }
519
520 /*
521 * Check the limited privilege scope up the call stack or the inherited
522 * parent thread call stack of this ACC.
523 */
524 if (parent != null) {
525 /*
526 * As an optimization, if the parent context is the inherited call
527 * stack context from a parent thread then checking the protection
528 * domains of the parent context is redundant since they have
529 * already been merged into the child thread's context by
530 * optimize(). When parent is set to an inherited context this
531 * context was not directly created by a limited scope
532 * doPrivileged() and it does not have its own limited permissions.
533 */
534 if (permissions == null) {
535 parent.checkPermission2(perm);
536 } else {
537 parent.checkPermission(perm);
538 }
539 }
540 }
541
542 /**
543 * Take the stack-based context (this) and combine it with the
544 * privileged or inherited context, if need be. Any limited
545 * privilege scope is flagged regardless of whether the assigned
546 * context comes from an immediately enclosing limited doPrivileged().
547 * The limited privilege scope can indirectly flow from the inherited
548 * parent thread or an assigned context previously captured by getContext().
549 */
550 AccessControlContext optimize() {
551 // the assigned (privileged or inherited) context
552 AccessControlContext acc;
553 DomainCombiner combiner = null;
554 AccessControlContext parent = null;
555 Permission[] permissions = null;
556
557 if (isPrivileged) {
558 acc = privilegedContext;
559 if (acc != null) {
560 /*
561 * If the context is from a limited scope doPrivileged() then
562 * copy the permissions and parent fields out of the wrapper
563 * context that was created to hold them.
564 */
565 if (acc.isWrapped) {
566 permissions = acc.permissions;
567 parent = acc.parent;
568 }
569 }
570 } else {
571 acc = AccessController.getInheritedAccessControlContext();
572 if (acc != null) {
573 /*
574 * If the inherited context is constrained by a limited scope
575 * doPrivileged() then set it as our parent so we will process
576 * the non-domain-related state.
577 */
578 if (acc.isLimited) {
579 parent = acc;
580 }
581 }
582 }
583
584 // this.context could be null if only system code is on the stack;
585 // in that case, ignore the stack context
586 boolean skipStack = (context == null);
587
588 // acc.context could be null if only system code was involved;
589 // in that case, ignore the assigned context
590 boolean skipAssigned = (acc == null || acc.context == null);
591 ProtectionDomain[] assigned = (skipAssigned) ? null : acc.context;
592 ProtectionDomain[] pd;
593
594 // if there is no enclosing limited privilege scope on the stack or
595 // inherited from a parent thread
596 boolean skipLimited = ((acc == null || !acc.isWrapped) && parent == null);
597
598 if (acc != null && acc.combiner != null) {
599 // let the assigned acc's combiner do its thing
600 if (getDebug() != null) {
601 debug.println("AccessControlContext invoking the Combiner");
602 }
603
604 // No need to clone current and assigned.context
605 // combine() will not update them
606 combiner = acc.combiner;
607 pd = combiner.combine(context, assigned);
608 } else {
609 if (skipStack) {
610 if (skipAssigned) {
611 calculateFields(acc, parent, permissions);
612 return this;
613 } else if (skipLimited) {
614 return acc;
615 }
616 } else if (assigned != null) {
617 if (skipLimited) {
618 // optimization: if there is a single stack domain and
619 // that domain is already in the assigned context; no
620 // need to combine
621 if (context.length == 1 && context[0] == assigned[0]) {
622 return acc;
623 }
624 }
625 }
626
627 pd = combine(context, assigned);
628 if (skipLimited && !skipAssigned && pd == assigned) {
629 return acc;
630 } else if (skipAssigned && pd == context) {
631 calculateFields(acc, parent, permissions);
632 return this;
633 }
634 }
635
636 // Reuse existing ACC
637 this.context = pd;
638 this.combiner = combiner;
639 this.isPrivileged = false;
640
641 calculateFields(acc, parent, permissions);
642 return this;
643 }
644
645
646 /*
647 * Combine the current (stack) and assigned domains.
648 */
649 private static ProtectionDomain[] combine(ProtectionDomain[] current,
650 ProtectionDomain[] assigned) {
651
652 // current could be null if only system code is on the stack;
653 // in that case, ignore the stack context
654 boolean skipStack = (current == null);
655
656 // assigned could be null if only system code was involved;
657 // in that case, ignore the assigned context
658 boolean skipAssigned = (assigned == null);
659
660 int slen = (skipStack) ? 0 : current.length;
661
662 // optimization: if there is no assigned context and the stack length
663 // is less then or equal to two; there is no reason to compress the
664 // stack context, it already is
665 if (skipAssigned && slen <= 2) {
666 return current;
667 }
668
669 int n = (skipAssigned) ? 0 : assigned.length;
670
671 // now we combine both of them, and create a new context
672 ProtectionDomain[] pd = new ProtectionDomain[slen + n];
673
674 // first copy in the assigned context domains, no need to compress
675 if (!skipAssigned) {
676 System.arraycopy(assigned, 0, pd, 0, n);
677 }
678
679 // now add the stack context domains, discarding nulls and duplicates
680 outer:
681 for (int i = 0; i < slen; i++) {
682 ProtectionDomain sd = current[i];
683 if (sd != null) {
684 for (int j = 0; j < n; j++) {
685 if (sd == pd[j]) {
686 continue outer;
687 }
688 }
689 pd[n++] = sd;
690 }
691 }
692
693 // if length isn't equal, we need to shorten the array
694 if (n != pd.length) {
695 // optimization: if we didn't really combine anything
696 if (!skipAssigned && n == assigned.length) {
697 return assigned;
698 } else if (skipAssigned && n == slen) {
699 return current;
700 }
701 ProtectionDomain[] tmp = new ProtectionDomain[n];
702 System.arraycopy(pd, 0, tmp, 0, n);
703 pd = tmp;
704 }
705
706 return pd;
707 }
708
709
710 /*
711 * Calculate the additional domains that could potentially be reached via
712 * limited privilege scope. Mark the context as being subject to limited
713 * privilege scope unless the reachable domains (if any) are already
714 * contained in this domain context (in which case any limited
715 * privilege scope checking would be redundant).
716 */
717 private void calculateFields(AccessControlContext assigned,
718 AccessControlContext parent, Permission[] permissions)
719 {
720 ProtectionDomain[] parentLimit = null;
721 ProtectionDomain[] assignedLimit = null;
722 ProtectionDomain[] newLimit;
723
724 parentLimit = (parent != null)? parent.limitedContext: null;
725 assignedLimit = (assigned != null)? assigned.limitedContext: null;
726 newLimit = combine(parentLimit, assignedLimit);
727 if (newLimit != null) {
728 if (context == null || !containsAllPDs(newLimit, context)) {
729 this.limitedContext = newLimit;
730 this.permissions = permissions;
731 this.parent = parent;
732 this.isLimited = true;
733 }
734 }
735 }
736
737
738 /**
739 * Checks two AccessControlContext objects for equality.
740 * Checks that {@code obj} is
741 * an AccessControlContext and has the same set of ProtectionDomains
742 * as this context.
743 *
744 * @param obj the object we are testing for equality with this object.
745 * @return true if {@code obj} is an AccessControlContext, and has the
746 * same set of ProtectionDomains as this context, false otherwise.
747 */
748 public boolean equals(Object obj) {
749 if (obj == this)
750 return true;
751
752 if (! (obj instanceof AccessControlContext))
753 return false;
754
755 AccessControlContext that = (AccessControlContext) obj;
756
757 if (!equalContext(that))
758 return false;
759
760 if (!equalLimitedContext(that))
761 return false;
762
763 return true;
764 }
765
766 /*
767 * Compare for equality based on state that is free of limited
768 * privilege complications.
769 */
770 private boolean equalContext(AccessControlContext that) {
771 if (!equalPDs(this.context, that.context))
772 return false;
773
774 if (this.combiner == null && that.combiner != null)
775 return false;
776
777 if (this.combiner != null && !this.combiner.equals(that.combiner))
778 return false;
779
780 return true;
781 }
782
783 private boolean equalPDs(ProtectionDomain[] a, ProtectionDomain[] b) {
784 if (a == null) {
785 return (b == null);
786 }
787
788 if (b == null)
789 return false;
790
791 if (!(containsAllPDs(a, b) && containsAllPDs(b, a)))
792 return false;
793
794 return true;
795 }
796
797 /*
798 * Compare for equality based on state that is captured during a
799 * call to AccessController.getContext() when a limited privilege
800 * scope is in effect.
801 */
802 private boolean equalLimitedContext(AccessControlContext that) {
803 if (that == null)
804 return false;
805
806 /*
807 * If neither instance has limited privilege scope then we're done.
808 */
809 if (!this.isLimited && !that.isLimited)
810 return true;
811
812 /*
813 * If only one instance has limited privilege scope then we're done.
814 */
815 if (!(this.isLimited && that.isLimited))
816 return false;
817
818 /*
819 * Wrapped instances should never escape outside the implementation
820 * this class and AccessController so this will probably never happen
821 * but it only makes any sense to compare if they both have the same
822 * isWrapped state.
823 */
824 if ((this.isWrapped && !that.isWrapped) ||
825 (!this.isWrapped && that.isWrapped)) {
826 return false;
827 }
828
829 if (this.permissions == null && that.permissions != null)
830 return false;
831
832 if (this.permissions != null && that.permissions == null)
833 return false;
834
835 if (!(this.containsAllLimits(that) && that.containsAllLimits(this)))
836 return false;
837
838 /*
839 * Skip through any wrapped contexts.
840 */
841 AccessControlContext thisNextPC = getNextPC(this);
842 AccessControlContext thatNextPC = getNextPC(that);
843
844 /*
845 * The protection domains and combiner of a privilegedContext are
846 * not relevant because they have already been included in the context
847 * of this instance by optimize() so we only care about any limited
848 * privilege state they may have.
849 */
850 if (thisNextPC == null && thatNextPC != null && thatNextPC.isLimited)
851 return false;
852
853 if (thisNextPC != null && !thisNextPC.equalLimitedContext(thatNextPC))
854 return false;
855
856 if (this.parent == null && that.parent != null)
857 return false;
858
859 if (this.parent != null && !this.parent.equals(that.parent))
860 return false;
861
862 return true;
863 }
864
865 /*
866 * Follow the privilegedContext link making our best effort to skip
867 * through any wrapper contexts.
868 */
869 private static AccessControlContext getNextPC(AccessControlContext acc) {
870 while (acc != null && acc.privilegedContext != null) {
871 acc = acc.privilegedContext;
872 if (!acc.isWrapped)
873 return acc;
874 }
875 return null;
876 }
877
878 private static boolean containsAllPDs(ProtectionDomain[] thisContext,
879 ProtectionDomain[] thatContext) {
880 boolean match = false;
881
882 //
883 // ProtectionDomains within an ACC currently cannot be null
884 // and this is enforced by the constructor and the various
885 // optimize methods. However, historically this logic made attempts
886 // to support the notion of a null PD and therefore this logic continues
887 // to support that notion.
888 ProtectionDomain thisPd;
889 for (int i = 0; i < thisContext.length; i++) {
890 match = false;
891 if ((thisPd = thisContext[i]) == null) {
892 for (int j = 0; (j < thatContext.length) && !match; j++) {
893 match = (thatContext[j] == null);
894 }
895 } else {
896 Class<?> thisPdClass = thisPd.getClass();
897 ProtectionDomain thatPd;
898 for (int j = 0; (j < thatContext.length) && !match; j++) {
899 thatPd = thatContext[j];
900
901 // Class check required to avoid PD exposure (4285406)
902 match = (thatPd != null &&
903 thisPdClass == thatPd.getClass() && thisPd.equals(thatPd));
904 }
905 }
906 if (!match) return false;
907 }
908 return match;
909 }
910
911 private boolean containsAllLimits(AccessControlContext that) {
912 boolean match = false;
913 Permission thisPerm;
914
915 if (this.permissions == null && that.permissions == null)
916 return true;
917
918 for (int i = 0; i < this.permissions.length; i++) {
919 Permission limit = this.permissions[i];
920 Class <?> limitClass = limit.getClass();
921 match = false;
922 for (int j = 0; (j < that.permissions.length) && !match; j++) {
923 Permission perm = that.permissions[j];
924 match = (limitClass.equals(perm.getClass()) &&
925 limit.equals(perm));
926 }
927 if (!match) return false;
928 }
929 return match;
930 }
931
932
933 /**
934 * Returns the hash code value for this context. The hash code
935 * is computed by exclusive or-ing the hash code of all the protection
936 * domains in the context together.
937 *
938 * @return a hash code value for this context.
939 */
940
941 public int hashCode() {
942 int hashCode = 0;
943
944 if (context == null)
945 return hashCode;
946
947 for (int i =0; i < context.length; i++) {
948 if (context[i] != null)
949 hashCode ^= context[i].hashCode();
950 }
951
952 return hashCode;
953 }
954 }