osfmk/kern/exception.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  */
  58
  59 #include <mach/mach_types.h>
  60 #include <mach/boolean.h>
  61 #include <mach/kern_return.h>
  62 #include <mach/message.h>
  63 #include <mach/port.h>
  64 #include <mach/mig_errors.h>
  65 #include <mach/task.h>
  66 #include <mach/thread_status.h>
  67 #include <mach/exception_types.h>
  68 #include <mach/exc.h>
  69 #include <mach/mach_exc.h>
  70
  71 #include <ipc/port.h>
  72 #include <ipc/ipc_entry.h>
  73 #include <ipc/ipc_object.h>
  74 #include <ipc/ipc_notify.h>
  75 #include <ipc/ipc_space.h>
  76 #include <ipc/ipc_pset.h>
  77 #include <ipc/ipc_machdep.h>
  78
  79 #include <kern/counters.h>
  80 #include <kern/ipc_tt.h>
  81 #include <kern/task.h>
  82 #include <kern/thread.h>
  83 #include <kern/processor.h>
  84 #include <kern/sched.h>
  85 #include <kern/sched_prim.h>
  86 #include <kern/host.h>
  87 #include <kern/misc_protos.h>
  88 #include <kern/ux_handler.h>
  89
  90 #include <security/mac_mach_internal.h>
  91 #include <string.h>
  92
  93 #include <pexpert/pexpert.h>
  94
  95 extern int panic_on_exception_triage;
  96
  97 unsigned long c_thr_exc_raise = 0;
  98 unsigned long c_thr_exc_raise_state = 0;
  99 unsigned long c_thr_exc_raise_state_id = 0;
 100 unsigned long c_tsk_exc_raise = 0;
 101 unsigned long c_tsk_exc_raise_state = 0;
 102 unsigned long c_tsk_exc_raise_state_id = 0;
 103
 104 /* forward declarations */
 105 kern_return_t exception_deliver(
 106         thread_t                thread,
 107         exception_type_t        exception,
 108         mach_exception_data_t   code,
 109         mach_msg_type_number_t  codeCnt,
 110         struct exception_action *excp,
 111         lck_mtx_t                       *mutex);
 112
 113 static kern_return_t
 114 check_exc_receiver_dependency(
 115         exception_type_t exception,
 116         struct exception_action *excp,
 117         lck_mtx_t *mutex);
 118
 119 #ifdef MACH_BSD
 120 kern_return_t bsd_exception(
 121         exception_type_t        exception,
 122         mach_exception_data_t   code,
 123         mach_msg_type_number_t  codeCnt);
 124 #endif /* MACH_BSD */
 125
 126 /*
 127  *      Routine:        exception_deliver
 128  *      Purpose:
 129  *              Make an upcall to the exception server provided.
 130  *      Conditions:
 131  *              Nothing locked and no resources held.
 132  *              Called from an exception context, so
 133  *              thread_exception_return and thread_kdb_return
 134  *              are possible.
 135  *      Returns:
 136  *              KERN_SUCCESS if the exception was handled
 137  */
 138 kern_return_t
 139 exception_deliver(
 140         thread_t                thread,
 141         exception_type_t        exception,
 142         mach_exception_data_t   code,
 143         mach_msg_type_number_t  codeCnt,
 144         struct exception_action *excp,
 145         lck_mtx_t                       *mutex)
 146 {
 147         ipc_port_t              exc_port = IPC_PORT_NULL;
 148         exception_data_type_t   small_code[EXCEPTION_CODE_MAX];
 149         int                     code64;
 150         int                     behavior;
 151         int                     flavor;
 152         kern_return_t           kr;
 153         task_t task;
 154         ipc_port_t thread_port = IPC_PORT_NULL, task_port = IPC_PORT_NULL;
 155
 156         /*
 157          *  Save work if we are terminating.
 158          *  Just go back to our AST handler.
 159          */
 160         if (!thread->active && !thread->inspection) {
 161                 return KERN_SUCCESS;
 162         }
 163
 164         /*
 165          * If there are no exception actions defined for this entity,
 166          * we can't deliver here.
 167          */
 168         if (excp == NULL) {
 169                 return KERN_FAILURE;
 170         }
 171
 172         assert(exception < EXC_TYPES_COUNT);
 173         if (exception >= EXC_TYPES_COUNT) {
 174                 return KERN_FAILURE;
 175         }
 176
 177         excp = &excp[exception];
 178
 179         /*
 180          * Snapshot the exception action data under lock for consistency.
 181          * Hold a reference to the port over the exception_raise_* calls
 182          * so it can't be destroyed.  This seems like overkill, but keeps
 183          * the port from disappearing between now and when
 184          * ipc_object_copyin_from_kernel is finally called.
 185          */
 186         lck_mtx_lock(mutex);
 187         exc_port = excp->port;
 188         if (!IP_VALID(exc_port)) {
 189                 lck_mtx_unlock(mutex);
 190                 return KERN_FAILURE;
 191         }
 192         ip_lock(exc_port);
 193         if (!ip_active(exc_port)) {
 194                 ip_unlock(exc_port);
 195                 lck_mtx_unlock(mutex);
 196                 return KERN_FAILURE;
 197         }
 198         ip_reference(exc_port);
 199         exc_port->ip_srights++;
 200         ip_unlock(exc_port);
 201
 202         flavor = excp->flavor;
 203         behavior = excp->behavior;
 204         lck_mtx_unlock(mutex);
 205
 206         code64 = (behavior & MACH_EXCEPTION_CODES);
 207         behavior &= ~MACH_EXCEPTION_CODES;
 208
 209         if (!code64) {
 210                 small_code[0] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[0]);
 211                 small_code[1] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[1]);
 212         }
 213
 214         task = thread->task;
 215
 216 #if CONFIG_MACF
 217         /* Now is a reasonably good time to check if the exception action is
 218          * permitted for this process, because after this point we will send
 219          * the message out almost certainly.
 220          * As with other failures, exception_triage_thread will go on
 221          * to the next level.
 222          */
 223
 224         /* The global exception-to-signal translation port is safe to be an exception handler. */
 225         if (is_ux_handler_port(exc_port) == FALSE &&
 226             mac_exc_action_check_exception_send(task, excp) != 0) {
 227                 kr = KERN_FAILURE;
 228                 goto out_release_right;
 229         }
 230 #endif
 231
 232         if (behavior != EXCEPTION_STATE) {
 233                 if (thread != current_thread() || exception == EXC_CORPSE_NOTIFY) {
 234                         task_reference(task);
 235                         task_port = convert_task_to_port(task);
 236                         /* task ref consumed */
 237                         thread_reference(thread);
 238                         thread_port = convert_thread_to_port(thread);
 239                         /* thread ref consumed */
 240                 } else {
 241                         task_port = retrieve_task_self_fast(thread->task);
 242                         thread_port = retrieve_thread_self_fast(thread);
 243                 }
 244         }
 245
 246         switch (behavior) {
 247         case EXCEPTION_STATE: {
 248                 mach_msg_type_number_t state_cnt;
 249                 thread_state_data_t state;
 250
 251                 c_thr_exc_raise_state++;
 252                 state_cnt = _MachineStateCount[flavor];
 253                 kr = thread_getstatus_to_user(thread, flavor,
 254                     (thread_state_t)state,
 255                     &state_cnt);
 256                 if (kr == KERN_SUCCESS) {
 257                         if (code64) {
 258                                 kr = mach_exception_raise_state(exc_port,
 259                                     exception,
 260                                     code,
 261                                     codeCnt,
 262                                     &flavor,
 263                                     state, state_cnt,
 264                                     state, &state_cnt);
 265                         } else {
 266                                 kr = exception_raise_state(exc_port, exception,
 267                                     small_code,
 268                                     codeCnt,
 269                                     &flavor,
 270                                     state, state_cnt,
 271                                     state, &state_cnt);
 272                         }
 273                         if (kr == KERN_SUCCESS) {
 274                                 if (exception != EXC_CORPSE_NOTIFY) {
 275                                         kr = thread_setstatus_from_user(thread, flavor,
 276                                             (thread_state_t)state,
 277                                             state_cnt);
 278                                 }
 279                                 goto out_release_right;
 280                         }
 281                 }
 282
 283                 goto out_release_right;
 284         }
 285
 286         case EXCEPTION_DEFAULT:
 287                 c_thr_exc_raise++;
 288                 if (code64) {
 289                         kr = mach_exception_raise(exc_port,
 290                             thread_port,
 291                             task_port,
 292                             exception,
 293                             code,
 294                             codeCnt);
 295                 } else {
 296                         kr = exception_raise(exc_port,
 297                             thread_port,
 298                             task_port,
 299                             exception,
 300                             small_code,
 301                             codeCnt);
 302                 }
 303
 304                 goto out_release_right;
 305
 306         case EXCEPTION_STATE_IDENTITY: {
 307                 mach_msg_type_number_t state_cnt;
 308                 thread_state_data_t state;
 309
 310                 c_thr_exc_raise_state_id++;
 311                 state_cnt = _MachineStateCount[flavor];
 312                 kr = thread_getstatus_to_user(thread, flavor,
 313                     (thread_state_t)state,
 314                     &state_cnt);
 315                 if (kr == KERN_SUCCESS) {
 316                         if (code64) {
 317                                 kr = mach_exception_raise_state_identity(
 318                                         exc_port,
 319                                         thread_port,
 320                                         task_port,
 321                                         exception,
 322                                         code,
 323                                         codeCnt,
 324                                         &flavor,
 325                                         state, state_cnt,
 326                                         state, &state_cnt);
 327                         } else {
 328                                 kr = exception_raise_state_identity(exc_port,
 329                                     thread_port,
 330                                     task_port,
 331                                     exception,
 332                                     small_code,
 333                                     codeCnt,
 334                                     &flavor,
 335                                     state, state_cnt,
 336                                     state, &state_cnt);
 337                         }
 338
 339                         if (kr == KERN_SUCCESS) {
 340                                 if (exception != EXC_CORPSE_NOTIFY) {
 341                                         kr = thread_setstatus_from_user(thread, flavor,
 342                                             (thread_state_t)state,
 343                                             state_cnt);
 344                                 }
 345                                 goto out_release_right;
 346                         }
 347                 }
 348
 349                 goto out_release_right;
 350         }
 351
 352         default:
 353                 panic("bad exception behavior!");
 354                 return KERN_FAILURE;
 355         }/* switch */
 356
 357 out_release_right:
 358
 359         if (task_port) {
 360                 ipc_port_release_send(task_port);
 361         }
 362
 363         if (thread_port) {
 364                 ipc_port_release_send(thread_port);
 365         }
 366
 367         if (exc_port) {
 368                 ipc_port_release_send(exc_port);
 369         }
 370
 371         return kr;
 372 }
 373
 374 /*
 375  * Routine: check_exc_receiver_dependency
 376  * Purpose:
 377  *      Verify that the port destined for receiving this exception is not
 378  *      on the current task. This would cause hang in kernel for
 379  *      EXC_CRASH primarily. Note: If port is transferred
 380  *      between check and delivery then deadlock may happen.
 381  *
 382  * Conditions:
 383  *              Nothing locked and no resources held.
 384  *              Called from an exception context.
 385  * Returns:
 386  *      KERN_SUCCESS if its ok to send exception message.
 387  */
 388 kern_return_t
 389 check_exc_receiver_dependency(
 390         exception_type_t exception,
 391         struct exception_action *excp,
 392         lck_mtx_t *mutex)
 393 {
 394         kern_return_t retval = KERN_SUCCESS;
 395
 396         if (excp == NULL || exception != EXC_CRASH) {
 397                 return retval;
 398         }
 399
 400         task_t task = current_task();
 401         lck_mtx_lock(mutex);
 402         ipc_port_t xport = excp[exception].port;
 403         if (IP_VALID(xport)
 404             && ip_active(xport)
 405             && task->itk_space == xport->ip_receiver) {
 406                 retval = KERN_FAILURE;
 407         }
 408         lck_mtx_unlock(mutex);
 409         return retval;
 410 }
 411
 412
 413 /*
 414  *      Routine:        exception_triage_thread
 415  *      Purpose:
 416  *              The thread caught an exception.
 417  *              We make an up-call to the thread's exception server.
 418  *      Conditions:
 419  *              Nothing locked and no resources held.
 420  *              Called from an exception context, so
 421  *              thread_exception_return and thread_kdb_return
 422  *              are possible.
 423  *      Returns:
 424  *              KERN_SUCCESS if exception is handled by any of the handlers.
 425  */
 426 kern_return_t
 427 exception_triage_thread(
 428         exception_type_t        exception,
 429         mach_exception_data_t   code,
 430         mach_msg_type_number_t  codeCnt,
 431         thread_t                thread)
 432 {
 433         task_t                  task;
 434         host_priv_t             host_priv;
 435         lck_mtx_t               *mutex;
 436         kern_return_t   kr = KERN_FAILURE;
 437
 438         assert(exception != EXC_RPC_ALERT);
 439
 440         /*
 441          * If this behavior has been requested by the the kernel
 442          * (due to the boot environment), we should panic if we
 443          * enter this function.  This is intended as a debugging
 444          * aid; it should allow us to debug why we caught an
 445          * exception in environments where debugging is especially
 446          * difficult.
 447          */
 448         if (panic_on_exception_triage) {
 449                 panic("called exception_triage when it was forbidden by the boot environment");
 450         }
 451
 452         /*
 453          * Try to raise the exception at the activation level.
 454          */
 455         mutex = &thread->mutex;
 456         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, thread->exc_actions, mutex)) {
 457                 kr = exception_deliver(thread, exception, code, codeCnt, thread->exc_actions, mutex);
 458                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 459                         goto out;
 460                 }
 461         }
 462
 463         /*
 464          * Maybe the task level will handle it.
 465          */
 466         task = thread->task;
 467         mutex = &task->itk_lock_data;
 468         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, task->exc_actions, mutex)) {
 469                 kr = exception_deliver(thread, exception, code, codeCnt, task->exc_actions, mutex);
 470                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 471                         goto out;
 472                 }
 473         }
 474
 475         /*
 476          * How about at the host level?
 477          */
 478         host_priv = host_priv_self();
 479         mutex = &host_priv->lock;
 480
 481         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, host_priv->exc_actions, mutex)) {
 482                 kr = exception_deliver(thread, exception, code, codeCnt, host_priv->exc_actions, mutex);
 483                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 484                         goto out;
 485                 }
 486         }
 487
 488 out:
 489         if ((exception != EXC_CRASH) && (exception != EXC_RESOURCE) &&
 490             (exception != EXC_GUARD) && (exception != EXC_CORPSE_NOTIFY)) {
 491                 thread_exception_return();
 492         }
 493         return kr;
 494 }
 495
 496 /*
 497  *      Routine:        exception_triage
 498  *      Purpose:
 499  *              The current thread caught an exception.
 500  *              We make an up-call to the thread's exception server.
 501  *      Conditions:
 502  *              Nothing locked and no resources held.
 503  *              Called from an exception context, so
 504  *              thread_exception_return and thread_kdb_return
 505  *              are possible.
 506  *      Returns:
 507  *              KERN_SUCCESS if exception is handled by any of the handlers.
 508  */
 509 kern_return_t
 510 exception_triage(
 511         exception_type_t        exception,
 512         mach_exception_data_t   code,
 513         mach_msg_type_number_t  codeCnt)
 514 {
 515         thread_t thread = current_thread();
 516         return exception_triage_thread(exception, code, codeCnt, thread);
 517 }
 518
 519 kern_return_t
 520 bsd_exception(
 521         exception_type_t        exception,
 522         mach_exception_data_t   code,
 523         mach_msg_type_number_t  codeCnt)
 524 {
 525         task_t                  task;
 526         lck_mtx_t               *mutex;
 527         thread_t                self = current_thread();
 528         kern_return_t           kr;
 529
 530         /*
 531          * Maybe the task level will handle it.
 532          */
 533         task = current_task();
 534         mutex = &task->itk_lock_data;
 535
 536         kr = exception_deliver(self, exception, code, codeCnt, task->exc_actions, mutex);
 537
 538         if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 539                 return KERN_SUCCESS;
 540         }
 541         return KERN_FAILURE;
 542 }
 543
 544
 545 /*
 546  * Raise an exception on a task.
 547  * This should tell launchd to launch Crash Reporter for this task.
 548  */
 549 kern_return_t
 550 task_exception_notify(exception_type_t exception,
 551     mach_exception_data_type_t exccode, mach_exception_data_type_t excsubcode)
 552 {
 553         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 554         wait_interrupt_t                wsave;
 555         kern_return_t kr = KERN_SUCCESS;
 556
 557         code[0] = exccode;
 558         code[1] = excsubcode;
 559
 560         wsave = thread_interrupt_level(THREAD_UNINT);
 561         kr = exception_triage(exception, code, EXCEPTION_CODE_MAX);
 562         (void) thread_interrupt_level(wsave);
 563         return kr;
 564 }
 565
 566
 567 /*
 568  *      Handle interface for special performance monitoring
 569  *      This is a special case of the host exception handler
 570  */
 571 kern_return_t
 572 sys_perf_notify(thread_t thread, int pid)
 573 {
 574         host_priv_t             hostp;
 575         ipc_port_t              xport;
 576         wait_interrupt_t        wsave;
 577         kern_return_t           ret;
 578
 579         hostp = host_priv_self();       /* Get the host privileged ports */
 580         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 581         code[0] = 0xFF000001;           /* Set terminate code */
 582         code[1] = pid;          /* Pass out the pid */
 583
 584         struct task *task = thread->task;
 585         xport = hostp->exc_actions[EXC_RPC_ALERT].port;
 586
 587         /* Make sure we're not catching our own exception */
 588         if (!IP_VALID(xport) ||
 589             !ip_active(xport) ||
 590             task->itk_space == xport->data.receiver) {
 591                 return KERN_FAILURE;
 592         }
 593
 594         wsave = thread_interrupt_level(THREAD_UNINT);
 595         ret = exception_deliver(
 596                 thread,
 597                 EXC_RPC_ALERT,
 598                 code,
 599                 2,
 600                 hostp->exc_actions,
 601                 &hostp->lock);
 602         (void)thread_interrupt_level(wsave);
 603
 604         return ret;
 605 }