J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.security; |
| 27 | |
| 28 | import java.util.ArrayList; |
| 29 | import java.util.List; |
| 30 | import sun.security.util.Debug; |
| 31 | import sun.security.util.SecurityConstants; |
| 32 | |
| 33 | /** |
| 34 | * An AccessControlContext is used to make system resource access decisions |
| 35 | * based on the context it encapsulates. |
| 36 | * |
| 37 | * <p>More specifically, it encapsulates a context and |
| 38 | * has a single method, <code>checkPermission</code>, |
| 39 | * that is equivalent to the <code>checkPermission</code> method |
| 40 | * in the AccessController class, with one difference: The AccessControlContext |
| 41 | * <code>checkPermission</code> method makes access decisions based on the |
| 42 | * context it encapsulates, |
| 43 | * rather than that of the current execution thread. |
| 44 | * |
| 45 | * <p>Thus, the purpose of AccessControlContext is for those situations where |
| 46 | * a security check that should be made within a given context |
| 47 | * actually needs to be done from within a |
| 48 | * <i>different</i> context (for example, from within a worker thread). |
| 49 | * |
| 50 | * <p> An AccessControlContext is created by calling the |
| 51 | * <code>AccessController.getContext</code> method. |
| 52 | * The <code>getContext</code> method takes a "snapshot" |
| 53 | * of the current calling context, and places |
| 54 | * it in an AccessControlContext object, which it returns. A sample call is |
| 55 | * the following: |
| 56 | * |
| 57 | * <pre> |
| 58 | * AccessControlContext acc = AccessController.getContext() |
| 59 | * </pre> |
| 60 | * |
| 61 | * <p> |
| 62 | * Code within a different context can subsequently call the |
| 63 | * <code>checkPermission</code> method on the |
| 64 | * previously-saved AccessControlContext object. A sample call is the |
| 65 | * following: |
| 66 | * |
| 67 | * <pre> |
| 68 | * acc.checkPermission(permission) |
| 69 | * </pre> |
| 70 | * |
| 71 | * @see AccessController |
| 72 | * |
| 73 | * @author Roland Schemers |
| 74 | */ |
| 75 | |
| 76 | public final class AccessControlContext { |
| 77 | |
| 78 | private ProtectionDomain context[]; |
| 79 | private boolean isPrivileged; |
| 80 | |
| 81 | // Note: This field is directly used by the virtual machine |
| 82 | // native codes. Don't touch it. |
| 83 | private AccessControlContext privilegedContext; |
| 84 | |
| 85 | private DomainCombiner combiner = null; |
| 86 | |
| 87 | private static boolean debugInit = false; |
| 88 | private static Debug debug = null; |
| 89 | |
| 90 | static Debug getDebug() |
| 91 | { |
| 92 | if (debugInit) |
| 93 | return debug; |
| 94 | else { |
| 95 | if (Policy.isSet()) { |
| 96 | debug = Debug.getInstance("access"); |
| 97 | debugInit = true; |
| 98 | } |
| 99 | return debug; |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Create an AccessControlContext with the given set of ProtectionDomains. |
| 105 | * Context must not be null. Duplicate domains will be removed from the |
| 106 | * context. |
| 107 | * |
| 108 | * @param context the ProtectionDomains associated with this context. |
| 109 | * The non-duplicate domains are copied from the array. Subsequent |
| 110 | * changes to the array will not affect this AccessControlContext. |
| 111 | */ |
| 112 | public AccessControlContext(ProtectionDomain context[]) |
| 113 | { |
| 114 | if (context.length == 0) { |
| 115 | this.context = null; |
| 116 | } else if (context.length == 1) { |
| 117 | if (context[0] != null) { |
| 118 | this.context = context.clone(); |
| 119 | } else { |
| 120 | this.context = null; |
| 121 | } |
| 122 | } else { |
| 123 | List<ProtectionDomain> v = new ArrayList<ProtectionDomain>(context.length); |
| 124 | for (int i =0; i< context.length; i++) { |
| 125 | if ((context[i] != null) && (!v.contains(context[i]))) |
| 126 | v.add(context[i]); |
| 127 | } |
| 128 | this.context = new ProtectionDomain[v.size()]; |
| 129 | this.context = v.toArray(this.context); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | /** |
| 134 | * Create a new <code>AccessControlContext</code> with the given |
| 135 | * <code>AccessControlContext</code> and <code>DomainCombiner</code>. |
| 136 | * This constructor associates the provided |
| 137 | * <code>DomainCombiner</code> with the provided |
| 138 | * <code>AccessControlContext</code>. |
| 139 | * |
| 140 | * <p> |
| 141 | * |
| 142 | * @param acc the <code>AccessControlContext</code> associated |
| 143 | * with the provided <code>DomainCombiner</code>. |
| 144 | * |
| 145 | * @param combiner the <code>DomainCombiner</code> to be associated |
| 146 | * with the provided <code>AccessControlContext</code>. |
| 147 | * |
| 148 | * @exception NullPointerException if the provided |
| 149 | * <code>context</code> is <code>null</code>. |
| 150 | * |
| 151 | * @exception SecurityException if a security manager is installed and the |
| 152 | * caller does not have the "createAccessControlContext" |
| 153 | * {@link SecurityPermission} |
| 154 | * @since 1.3 |
| 155 | */ |
| 156 | public AccessControlContext(AccessControlContext acc, |
| 157 | DomainCombiner combiner) { |
| 158 | |
| 159 | SecurityManager sm = System.getSecurityManager(); |
| 160 | if (sm != null) { |
| 161 | sm.checkPermission(SecurityConstants.CREATE_ACC_PERMISSION); |
| 162 | } |
| 163 | |
| 164 | this.context = acc.context; |
| 165 | |
| 166 | // we do not need to run the combine method on the |
| 167 | // provided ACC. it was already "combined" when the |
| 168 | // context was originally retrieved. |
| 169 | // |
| 170 | // at this point in time, we simply throw away the old |
| 171 | // combiner and use the newly provided one. |
| 172 | this.combiner = combiner; |
| 173 | } |
| 174 | |
| 175 | /** |
| 176 | * package private for AccessController |
| 177 | */ |
| 178 | AccessControlContext(ProtectionDomain context[], DomainCombiner combiner) { |
| 179 | if (context != null) { |
| 180 | this.context = context.clone(); |
| 181 | } |
| 182 | this.combiner = combiner; |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * package private constructor for AccessController.getContext() |
| 187 | */ |
| 188 | |
| 189 | AccessControlContext(ProtectionDomain context[], |
| 190 | boolean isPrivileged) |
| 191 | { |
| 192 | this.context = context; |
| 193 | this.isPrivileged = isPrivileged; |
| 194 | } |
| 195 | |
| 196 | /** |
| 197 | * Returns true if this context is privileged. |
| 198 | */ |
| 199 | boolean isPrivileged() |
| 200 | { |
| 201 | return isPrivileged; |
| 202 | } |
| 203 | |
| 204 | /** |
| 205 | * get the assigned combiner from the privileged or inherited context |
| 206 | */ |
| 207 | DomainCombiner getAssignedCombiner() { |
| 208 | AccessControlContext acc; |
| 209 | if (isPrivileged) { |
| 210 | acc = privilegedContext; |
| 211 | } else { |
| 212 | acc = AccessController.getInheritedAccessControlContext(); |
| 213 | } |
| 214 | if (acc != null) { |
| 215 | return acc.combiner; |
| 216 | } |
| 217 | return null; |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * Get the <code>DomainCombiner</code> associated with this |
| 222 | * <code>AccessControlContext</code>. |
| 223 | * |
| 224 | * <p> |
| 225 | * |
| 226 | * @return the <code>DomainCombiner</code> associated with this |
| 227 | * <code>AccessControlContext</code>, or <code>null</code> |
| 228 | * if there is none. |
| 229 | * |
| 230 | * @exception SecurityException if a security manager is installed and |
| 231 | * the caller does not have the "getDomainCombiner" |
| 232 | * {@link SecurityPermission} |
| 233 | * @since 1.3 |
| 234 | */ |
| 235 | public DomainCombiner getDomainCombiner() { |
| 236 | |
| 237 | SecurityManager sm = System.getSecurityManager(); |
| 238 | if (sm != null) { |
| 239 | sm.checkPermission(SecurityConstants.GET_COMBINER_PERMISSION); |
| 240 | } |
| 241 | return combiner; |
| 242 | } |
| 243 | |
| 244 | /** |
| 245 | * Determines whether the access request indicated by the |
| 246 | * specified permission should be allowed or denied, based on |
| 247 | * the security policy currently in effect, and the context in |
| 248 | * this object. The request is allowed only if every ProtectionDomain |
| 249 | * in the context implies the permission. Otherwise the request is |
| 250 | * denied. |
| 251 | * |
| 252 | * <p> |
| 253 | * This method quietly returns if the access request |
| 254 | * is permitted, or throws a suitable AccessControlException otherwise. |
| 255 | * |
| 256 | * @param perm the requested permission. |
| 257 | * |
| 258 | * @exception AccessControlException if the specified permission |
| 259 | * is not permitted, based on the current security policy and the |
| 260 | * context encapsulated by this object. |
| 261 | * @exception NullPointerException if the permission to check for is null. |
| 262 | */ |
| 263 | public void checkPermission(Permission perm) |
| 264 | throws AccessControlException |
| 265 | { |
| 266 | boolean dumpDebug = false; |
| 267 | |
| 268 | if (perm == null) { |
| 269 | throw new NullPointerException("permission can't be null"); |
| 270 | } |
| 271 | if (getDebug() != null) { |
| 272 | // If "codebase" is not specified, we dump the info by default. |
| 273 | dumpDebug = !Debug.isOn("codebase="); |
| 274 | if (!dumpDebug) { |
| 275 | // If "codebase" is specified, only dump if the specified code |
| 276 | // value is in the stack. |
| 277 | for (int i = 0; context != null && i < context.length; i++) { |
| 278 | if (context[i].getCodeSource() != null && |
| 279 | context[i].getCodeSource().getLocation() != null && |
| 280 | Debug.isOn("codebase=" + context[i].getCodeSource().getLocation().toString())) { |
| 281 | dumpDebug = true; |
| 282 | break; |
| 283 | } |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | dumpDebug &= !Debug.isOn("permission=") || |
| 288 | Debug.isOn("permission=" + perm.getClass().getCanonicalName()); |
| 289 | |
| 290 | if (dumpDebug && Debug.isOn("stack")) { |
| 291 | Thread.currentThread().dumpStack(); |
| 292 | } |
| 293 | |
| 294 | if (dumpDebug && Debug.isOn("domain")) { |
| 295 | if (context == null) { |
| 296 | debug.println("domain (context is null)"); |
| 297 | } else { |
| 298 | for (int i=0; i< context.length; i++) { |
| 299 | debug.println("domain "+i+" "+context[i]); |
| 300 | } |
| 301 | } |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /* |
| 306 | * iterate through the ProtectionDomains in the context. |
| 307 | * Stop at the first one that doesn't allow the |
| 308 | * requested permission (throwing an exception). |
| 309 | * |
| 310 | */ |
| 311 | |
| 312 | /* if ctxt is null, all we had on the stack were system domains, |
| 313 | or the first domain was a Privileged system domain. This |
| 314 | is to make the common case for system code very fast */ |
| 315 | |
| 316 | if (context == null) |
| 317 | return; |
| 318 | |
| 319 | for (int i=0; i< context.length; i++) { |
| 320 | if (context[i] != null && !context[i].implies(perm)) { |
| 321 | if (dumpDebug) { |
| 322 | debug.println("access denied " + perm); |
| 323 | } |
| 324 | |
| 325 | if (Debug.isOn("failure")) { |
| 326 | // Want to make sure this is always displayed for failure, |
| 327 | // but do not want to display again if already displayed |
| 328 | // above. |
| 329 | if (!dumpDebug) { |
| 330 | debug.println("access denied " + perm); |
| 331 | } |
| 332 | Thread.currentThread().dumpStack(); |
| 333 | final ProtectionDomain pd = context[i]; |
| 334 | final Debug db = debug; |
| 335 | AccessController.doPrivileged (new PrivilegedAction<Void>() { |
| 336 | public Void run() { |
| 337 | db.println("domain that failed "+pd); |
| 338 | return null; |
| 339 | } |
| 340 | }); |
| 341 | } |
| 342 | throw new AccessControlException("access denied "+perm, perm); |
| 343 | } |
| 344 | } |
| 345 | |
| 346 | // allow if all of them allowed access |
| 347 | if (dumpDebug) { |
| 348 | debug.println("access allowed "+perm); |
| 349 | } |
| 350 | |
| 351 | return; |
| 352 | } |
| 353 | |
| 354 | /** |
| 355 | * Take the stack-based context (this) and combine it with the |
| 356 | * privileged or inherited context, if need be. |
| 357 | */ |
| 358 | AccessControlContext optimize() { |
| 359 | // the assigned (privileged or inherited) context |
| 360 | AccessControlContext acc; |
| 361 | if (isPrivileged) { |
| 362 | acc = privilegedContext; |
| 363 | } else { |
| 364 | acc = AccessController.getInheritedAccessControlContext(); |
| 365 | } |
| 366 | |
| 367 | // this.context could be null if only system code is on the stack; |
| 368 | // in that case, ignore the stack context |
| 369 | boolean skipStack = (context == null); |
| 370 | |
| 371 | // acc.context could be null if only system code was involved; |
| 372 | // in that case, ignore the assigned context |
| 373 | boolean skipAssigned = (acc == null || acc.context == null); |
| 374 | |
| 375 | if (acc != null && acc.combiner != null) { |
| 376 | // let the assigned acc's combiner do its thing |
| 377 | return goCombiner(context, acc); |
| 378 | } |
| 379 | |
| 380 | // optimization: if neither have contexts; return acc if possible |
| 381 | // rather than this, because acc might have a combiner |
| 382 | if (skipAssigned && skipStack) { |
| 383 | return this; |
| 384 | } |
| 385 | |
| 386 | // optimization: if there is no stack context; there is no reason |
| 387 | // to compress the assigned context, it already is compressed |
| 388 | if (skipStack) { |
| 389 | return acc; |
| 390 | } |
| 391 | |
| 392 | int slen = context.length; |
| 393 | |
| 394 | // optimization: if there is no assigned context and the stack length |
| 395 | // is less then or equal to two; there is no reason to compress the |
| 396 | // stack context, it already is |
| 397 | if (skipAssigned && slen <= 2) { |
| 398 | return this; |
| 399 | } |
| 400 | |
| 401 | // optimization: if there is a single stack domain and that domain |
| 402 | // is already in the assigned context; no need to combine |
| 403 | if ((slen == 1) && (context[0] == acc.context[0])) { |
| 404 | return acc; |
| 405 | } |
| 406 | |
| 407 | int n = (skipAssigned) ? 0 : acc.context.length; |
| 408 | |
| 409 | // now we combine both of them, and create a new context |
| 410 | ProtectionDomain pd[] = new ProtectionDomain[slen + n]; |
| 411 | |
| 412 | // first copy in the assigned context domains, no need to compress |
| 413 | if (!skipAssigned) { |
| 414 | System.arraycopy(acc.context, 0, pd, 0, n); |
| 415 | } |
| 416 | |
| 417 | // now add the stack context domains, discarding nulls and duplicates |
| 418 | outer: |
| 419 | for (int i = 0; i < context.length; i++) { |
| 420 | ProtectionDomain sd = context[i]; |
| 421 | if (sd != null) { |
| 422 | for (int j = 0; j < n; j++) { |
| 423 | if (sd == pd[j]) { |
| 424 | continue outer; |
| 425 | } |
| 426 | } |
| 427 | pd[n++] = sd; |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | // if length isn't equal, we need to shorten the array |
| 432 | if (n != pd.length) { |
| 433 | // optimization: if we didn't really combine anything |
| 434 | if (!skipAssigned && n == acc.context.length) { |
| 435 | return acc; |
| 436 | } else if (skipAssigned && n == slen) { |
| 437 | return this; |
| 438 | } |
| 439 | ProtectionDomain tmp[] = new ProtectionDomain[n]; |
| 440 | System.arraycopy(pd, 0, tmp, 0, n); |
| 441 | pd = tmp; |
| 442 | } |
| 443 | |
| 444 | // return new AccessControlContext(pd, false); |
| 445 | |
| 446 | // Reuse existing ACC |
| 447 | |
| 448 | this.context = pd; |
| 449 | this.combiner = null; |
| 450 | this.isPrivileged = false; |
| 451 | |
| 452 | return this; |
| 453 | } |
| 454 | |
| 455 | private AccessControlContext goCombiner(ProtectionDomain[] current, |
| 456 | AccessControlContext assigned) { |
| 457 | |
| 458 | // the assigned ACC's combiner is not null -- |
| 459 | // let the combiner do its thing |
| 460 | |
| 461 | // XXX we could add optimizations to 'current' here ... |
| 462 | |
| 463 | if (getDebug() != null) { |
| 464 | debug.println("AccessControlContext invoking the Combiner"); |
| 465 | } |
| 466 | |
| 467 | // No need to clone current and assigned.context |
| 468 | // combine() will not update them |
| 469 | ProtectionDomain[] combinedPds = assigned.combiner.combine( |
| 470 | current, assigned.context); |
| 471 | |
| 472 | // return new AccessControlContext(combinedPds, assigned.combiner); |
| 473 | |
| 474 | // Reuse existing ACC |
| 475 | this.context = combinedPds; |
| 476 | this.combiner = assigned.combiner; |
| 477 | this.isPrivileged = false; |
| 478 | |
| 479 | return this; |
| 480 | } |
| 481 | |
| 482 | /** |
| 483 | * Checks two AccessControlContext objects for equality. |
| 484 | * Checks that <i>obj</i> is |
| 485 | * an AccessControlContext and has the same set of ProtectionDomains |
| 486 | * as this context. |
| 487 | * <P> |
| 488 | * @param obj the object we are testing for equality with this object. |
| 489 | * @return true if <i>obj</i> is an AccessControlContext, and has the |
| 490 | * same set of ProtectionDomains as this context, false otherwise. |
| 491 | */ |
| 492 | public boolean equals(Object obj) { |
| 493 | if (obj == this) |
| 494 | return true; |
| 495 | |
| 496 | if (! (obj instanceof AccessControlContext)) |
| 497 | return false; |
| 498 | |
| 499 | AccessControlContext that = (AccessControlContext) obj; |
| 500 | |
| 501 | |
| 502 | if (context == null) { |
| 503 | return (that.context == null); |
| 504 | } |
| 505 | |
| 506 | if (that.context == null) |
| 507 | return false; |
| 508 | |
| 509 | if (!(this.containsAllPDs(that) && that.containsAllPDs(this))) |
| 510 | return false; |
| 511 | |
| 512 | if (this.combiner == null) |
| 513 | return (that.combiner == null); |
| 514 | |
| 515 | if (that.combiner == null) |
| 516 | return false; |
| 517 | |
| 518 | if (!this.combiner.equals(that.combiner)) |
| 519 | return false; |
| 520 | |
| 521 | return true; |
| 522 | } |
| 523 | |
| 524 | private boolean containsAllPDs(AccessControlContext that) { |
| 525 | boolean match = false; |
| 526 | // |
| 527 | // ProtectionDomains within an ACC currently cannot be null |
| 528 | // and this is enforced by the constructor and the various |
| 529 | // optimize methods. However, historically this logic made attempts |
| 530 | // to support the notion of a null PD and therefore this logic continues |
| 531 | // to support that notion. |
| 532 | ProtectionDomain thisPd; |
| 533 | for (int i = 0; i < context.length; i++) { |
| 534 | match = false; |
| 535 | if ((thisPd = context[i]) == null) { |
| 536 | for (int j = 0; (j < that.context.length) && !match; j++) { |
| 537 | match = (that.context[j] == null); |
| 538 | } |
| 539 | } else { |
| 540 | Class thisPdClass = thisPd.getClass(); |
| 541 | ProtectionDomain thatPd; |
| 542 | for (int j = 0; (j < that.context.length) && !match; j++) { |
| 543 | thatPd = that.context[j]; |
| 544 | |
| 545 | // Class check required to avoid PD exposure (4285406) |
| 546 | match = (thatPd != null && |
| 547 | thisPdClass == thatPd.getClass() && thisPd.equals(thatPd)); |
| 548 | } |
| 549 | } |
| 550 | if (!match) return false; |
| 551 | } |
| 552 | return match; |
| 553 | } |
| 554 | /** |
| 555 | * Returns the hash code value for this context. The hash code |
| 556 | * is computed by exclusive or-ing the hash code of all the protection |
| 557 | * domains in the context together. |
| 558 | * |
| 559 | * @return a hash code value for this context. |
| 560 | */ |
| 561 | |
| 562 | public int hashCode() { |
| 563 | int hashCode = 0; |
| 564 | |
| 565 | if (context == null) |
| 566 | return hashCode; |
| 567 | |
| 568 | for (int i =0; i < context.length; i++) { |
| 569 | if (context[i] != null) |
| 570 | hashCode ^= context[i].hashCode(); |
| 571 | } |
| 572 | return hashCode; |
| 573 | } |
| 574 | } |