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 bool panic_on_exception_triage = false;
  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 #if __has_feature(ptrauth_calls)
 127 extern int exit_with_pac_exception(
 128         void *proc,
 129         exception_type_t         exception,
 130         mach_exception_code_t    code,
 131         mach_exception_subcode_t subcode);
 132
 133 extern bool proc_is_traced(void *p);
 134 #endif /* __has_feature(ptrauth_calls) */
 135
 136 /*
 137  * Routine: exception_init
 138  * Purpose:
 139  *   Global initialization of state for exceptions.
 140  * Conditions:
 141  *   None.
 142  */
 143 void
 144 exception_init(void)
 145 {
 146         int tmp = 0;
 147
 148         if (PE_parse_boot_argn("-panic_on_exception_triage", &tmp, sizeof(tmp))) {
 149                 panic_on_exception_triage = true;
 150         }
 151 }
 152
 153 /*
 154  *      Routine:        exception_deliver
 155  *      Purpose:
 156  *              Make an upcall to the exception server provided.
 157  *      Conditions:
 158  *              Nothing locked and no resources held.
 159  *              Called from an exception context, so
 160  *              thread_exception_return and thread_kdb_return
 161  *              are possible.
 162  *      Returns:
 163  *              KERN_SUCCESS if the exception was handled
 164  */
 165 kern_return_t
 166 exception_deliver(
 167         thread_t                thread,
 168         exception_type_t        exception,
 169         mach_exception_data_t   code,
 170         mach_msg_type_number_t  codeCnt,
 171         struct exception_action *excp,
 172         lck_mtx_t                       *mutex)
 173 {
 174         ipc_port_t              exc_port = IPC_PORT_NULL;
 175         exception_data_type_t   small_code[EXCEPTION_CODE_MAX];
 176         int                     code64;
 177         int                     behavior;
 178         int                     flavor;
 179         kern_return_t           kr;
 180         task_t task;
 181         ipc_port_t thread_port = IPC_PORT_NULL, task_port = IPC_PORT_NULL;
 182
 183         /*
 184          *  Save work if we are terminating.
 185          *  Just go back to our AST handler.
 186          */
 187         if (!thread->active && !thread->inspection) {
 188                 return KERN_SUCCESS;
 189         }
 190
 191         /*
 192          * If there are no exception actions defined for this entity,
 193          * we can't deliver here.
 194          */
 195         if (excp == NULL) {
 196                 return KERN_FAILURE;
 197         }
 198
 199         assert(exception < EXC_TYPES_COUNT);
 200         if (exception >= EXC_TYPES_COUNT) {
 201                 return KERN_FAILURE;
 202         }
 203
 204         excp = &excp[exception];
 205
 206         /*
 207          * Snapshot the exception action data under lock for consistency.
 208          * Hold a reference to the port over the exception_raise_* calls
 209          * so it can't be destroyed.  This seems like overkill, but keeps
 210          * the port from disappearing between now and when
 211          * ipc_object_copyin_from_kernel is finally called.
 212          */
 213         lck_mtx_lock(mutex);
 214         exc_port = excp->port;
 215         if (!IP_VALID(exc_port)) {
 216                 lck_mtx_unlock(mutex);
 217                 return KERN_FAILURE;
 218         }
 219         ip_lock(exc_port);
 220         if (!ip_active(exc_port)) {
 221                 ip_unlock(exc_port);
 222                 lck_mtx_unlock(mutex);
 223                 return KERN_FAILURE;
 224         }
 225         ip_reference(exc_port);
 226         exc_port->ip_srights++;
 227         ip_unlock(exc_port);
 228
 229         flavor = excp->flavor;
 230         behavior = excp->behavior;
 231         lck_mtx_unlock(mutex);
 232
 233         code64 = (behavior & MACH_EXCEPTION_CODES);
 234         behavior &= ~MACH_EXCEPTION_MASK;
 235
 236         if (!code64) {
 237                 small_code[0] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[0]);
 238                 small_code[1] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[1]);
 239         }
 240
 241         task = thread->task;
 242
 243 #if CONFIG_MACF
 244         /* Now is a reasonably good time to check if the exception action is
 245          * permitted for this process, because after this point we will send
 246          * the message out almost certainly.
 247          * As with other failures, exception_triage_thread will go on
 248          * to the next level.
 249          */
 250
 251         /* The global exception-to-signal translation port is safe to be an exception handler. */
 252         if (is_ux_handler_port(exc_port) == FALSE &&
 253             mac_exc_action_check_exception_send(task, excp) != 0) {
 254                 kr = KERN_FAILURE;
 255                 goto out_release_right;
 256         }
 257 #endif
 258
 259         if (behavior != EXCEPTION_STATE) {
 260                 task_reference(task);
 261                 task_port = convert_task_to_port(task);
 262                 /* task ref consumed */
 263                 thread_reference(thread);
 264                 thread_port = convert_thread_to_port(thread);
 265                 /* thread ref consumed */
 266         }
 267
 268         switch (behavior) {
 269         case EXCEPTION_STATE: {
 270                 mach_msg_type_number_t state_cnt;
 271                 thread_state_data_t state;
 272
 273                 c_thr_exc_raise_state++;
 274                 state_cnt = _MachineStateCount[flavor];
 275                 kr = thread_getstatus_to_user(thread, flavor,
 276                     (thread_state_t)state,
 277                     &state_cnt);
 278                 if (kr == KERN_SUCCESS) {
 279                         if (code64) {
 280                                 kr = mach_exception_raise_state(exc_port,
 281                                     exception,
 282                                     code,
 283                                     codeCnt,
 284                                     &flavor,
 285                                     state, state_cnt,
 286                                     state, &state_cnt);
 287                         } else {
 288                                 kr = exception_raise_state(exc_port, exception,
 289                                     small_code,
 290                                     codeCnt,
 291                                     &flavor,
 292                                     state, state_cnt,
 293                                     state, &state_cnt);
 294                         }
 295                         if (kr == KERN_SUCCESS) {
 296                                 if (exception != EXC_CORPSE_NOTIFY) {
 297                                         kr = thread_setstatus_from_user(thread, flavor,
 298                                             (thread_state_t)state,
 299                                             state_cnt);
 300                                 }
 301                                 goto out_release_right;
 302                         }
 303                 }
 304
 305                 goto out_release_right;
 306         }
 307
 308         case EXCEPTION_DEFAULT:
 309                 c_thr_exc_raise++;
 310                 if (code64) {
 311                         kr = mach_exception_raise(exc_port,
 312                             thread_port,
 313                             task_port,
 314                             exception,
 315                             code,
 316                             codeCnt);
 317                 } else {
 318                         kr = exception_raise(exc_port,
 319                             thread_port,
 320                             task_port,
 321                             exception,
 322                             small_code,
 323                             codeCnt);
 324                 }
 325
 326                 goto out_release_right;
 327
 328         case EXCEPTION_STATE_IDENTITY: {
 329                 mach_msg_type_number_t state_cnt;
 330                 thread_state_data_t state;
 331
 332                 c_thr_exc_raise_state_id++;
 333                 state_cnt = _MachineStateCount[flavor];
 334                 kr = thread_getstatus_to_user(thread, flavor,
 335                     (thread_state_t)state,
 336                     &state_cnt);
 337                 if (kr == KERN_SUCCESS) {
 338                         if (code64) {
 339                                 kr = mach_exception_raise_state_identity(
 340                                         exc_port,
 341                                         thread_port,
 342                                         task_port,
 343                                         exception,
 344                                         code,
 345                                         codeCnt,
 346                                         &flavor,
 347                                         state, state_cnt,
 348                                         state, &state_cnt);
 349                         } else {
 350                                 kr = exception_raise_state_identity(exc_port,
 351                                     thread_port,
 352                                     task_port,
 353                                     exception,
 354                                     small_code,
 355                                     codeCnt,
 356                                     &flavor,
 357                                     state, state_cnt,
 358                                     state, &state_cnt);
 359                         }
 360
 361                         if (kr == KERN_SUCCESS) {
 362                                 if (exception != EXC_CORPSE_NOTIFY) {
 363                                         kr = thread_setstatus_from_user(thread, flavor,
 364                                             (thread_state_t)state,
 365                                             state_cnt);
 366                                 }
 367                                 goto out_release_right;
 368                         }
 369                 }
 370
 371                 goto out_release_right;
 372         }
 373
 374         default:
 375                 panic("bad exception behavior!");
 376                 return KERN_FAILURE;
 377         }/* switch */
 378
 379 out_release_right:
 380
 381         if (task_port) {
 382                 ipc_port_release_send(task_port);
 383         }
 384
 385         if (thread_port) {
 386                 ipc_port_release_send(thread_port);
 387         }
 388
 389         if (exc_port) {
 390                 ipc_port_release_send(exc_port);
 391         }
 392
 393         return kr;
 394 }
 395
 396 /*
 397  * Routine: check_exc_receiver_dependency
 398  * Purpose:
 399  *      Verify that the port destined for receiving this exception is not
 400  *      on the current task. This would cause hang in kernel for
 401  *      EXC_CRASH primarily. Note: If port is transferred
 402  *      between check and delivery then deadlock may happen.
 403  *
 404  * Conditions:
 405  *              Nothing locked and no resources held.
 406  *              Called from an exception context.
 407  * Returns:
 408  *      KERN_SUCCESS if its ok to send exception message.
 409  */
 410 kern_return_t
 411 check_exc_receiver_dependency(
 412         exception_type_t exception,
 413         struct exception_action *excp,
 414         lck_mtx_t *mutex)
 415 {
 416         kern_return_t retval = KERN_SUCCESS;
 417
 418         if (excp == NULL || exception != EXC_CRASH) {
 419                 return retval;
 420         }
 421
 422         task_t task = current_task();
 423         lck_mtx_lock(mutex);
 424         ipc_port_t xport = excp[exception].port;
 425         if (IP_VALID(xport)
 426             && ip_active(xport)
 427             && task->itk_space == xport->ip_receiver) {
 428                 retval = KERN_FAILURE;
 429         }
 430         lck_mtx_unlock(mutex);
 431         return retval;
 432 }
 433
 434
 435 /*
 436  *      Routine:        exception_triage_thread
 437  *      Purpose:
 438  *              The thread caught an exception.
 439  *              We make an up-call to the thread's exception server.
 440  *      Conditions:
 441  *              Nothing locked and no resources held.
 442  *              Called from an exception context, so
 443  *              thread_exception_return and thread_kdb_return
 444  *              are possible.
 445  *      Returns:
 446  *              KERN_SUCCESS if exception is handled by any of the handlers.
 447  */
 448 kern_return_t
 449 exception_triage_thread(
 450         exception_type_t        exception,
 451         mach_exception_data_t   code,
 452         mach_msg_type_number_t  codeCnt,
 453         thread_t                thread)
 454 {
 455         task_t                  task;
 456         host_priv_t             host_priv;
 457         lck_mtx_t               *mutex;
 458         kern_return_t   kr = KERN_FAILURE;
 459
 460         assert(exception != EXC_RPC_ALERT);
 461
 462         /*
 463          * If this behavior has been requested by the the kernel
 464          * (due to the boot environment), we should panic if we
 465          * enter this function.  This is intended as a debugging
 466          * aid; it should allow us to debug why we caught an
 467          * exception in environments where debugging is especially
 468          * difficult.
 469          */
 470         if (panic_on_exception_triage) {
 471                 panic("called exception_triage when it was forbidden by the boot environment");
 472         }
 473
 474         /*
 475          * Try to raise the exception at the activation level.
 476          */
 477         mutex = &thread->mutex;
 478         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, thread->exc_actions, mutex)) {
 479                 kr = exception_deliver(thread, exception, code, codeCnt, thread->exc_actions, mutex);
 480                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 481                         goto out;
 482                 }
 483         }
 484
 485         /*
 486          * Maybe the task level will handle it.
 487          */
 488         task = thread->task;
 489         mutex = &task->itk_lock_data;
 490         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, task->exc_actions, mutex)) {
 491                 kr = exception_deliver(thread, exception, code, codeCnt, task->exc_actions, mutex);
 492                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 493                         goto out;
 494                 }
 495         }
 496
 497         /*
 498          * How about at the host level?
 499          */
 500         host_priv = host_priv_self();
 501         mutex = &host_priv->lock;
 502
 503         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, host_priv->exc_actions, mutex)) {
 504                 kr = exception_deliver(thread, exception, code, codeCnt, host_priv->exc_actions, mutex);
 505                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 506                         goto out;
 507                 }
 508         }
 509
 510 out:
 511         if ((exception != EXC_CRASH) && (exception != EXC_RESOURCE) &&
 512             (exception != EXC_GUARD) && (exception != EXC_CORPSE_NOTIFY)) {
 513                 thread_exception_return();
 514         }
 515         return kr;
 516 }
 517
 518 /*
 519  *      Routine:        exception_triage
 520  *      Purpose:
 521  *              The current thread caught an exception.
 522  *              We make an up-call to the thread's exception server.
 523  *      Conditions:
 524  *              Nothing locked and no resources held.
 525  *              Called from an exception context, so
 526  *              thread_exception_return and thread_kdb_return
 527  *              are possible.
 528  *      Returns:
 529  *              KERN_SUCCESS if exception is handled by any of the handlers.
 530  */
 531 kern_return_t
 532 exception_triage(
 533         exception_type_t        exception,
 534         mach_exception_data_t   code,
 535         mach_msg_type_number_t  codeCnt)
 536 {
 537         thread_t thread = current_thread();
 538 #if __has_feature(ptrauth_calls)
 539         /*
 540          * If it is a ptrauth violation, then check if the task has the TF_PAC_EXC_FATAL
 541          * flag set and isn't being ptraced. If so, terminate the task via exit_with_reason
 542          */
 543         if (exception & EXC_PTRAUTH_BIT) {
 544                 exception &= ~EXC_PTRAUTH_BIT;
 545
 546                 boolean_t traced_flag = FALSE;
 547                 task_t task = thread->task;
 548                 void *proc = task->bsd_info;
 549
 550                 if (task->bsd_info) {
 551                         traced_flag = proc_is_traced(proc);
 552                 }
 553
 554                 if (task_is_pac_exception_fatal(current_task()) && !traced_flag) {
 555                         exit_with_pac_exception(proc, exception, code[0], code[1]);
 556                         thread_exception_return();
 557                         /* NOT_REACHABLE */
 558                 }
 559         }
 560 #endif /* __has_feature(ptrauth_calls) */
 561         return exception_triage_thread(exception, code, codeCnt, thread);
 562 }
 563
 564 kern_return_t
 565 bsd_exception(
 566         exception_type_t        exception,
 567         mach_exception_data_t   code,
 568         mach_msg_type_number_t  codeCnt)
 569 {
 570         task_t                  task;
 571         lck_mtx_t               *mutex;
 572         thread_t                self = current_thread();
 573         kern_return_t           kr;
 574
 575         /*
 576          * Maybe the task level will handle it.
 577          */
 578         task = current_task();
 579         mutex = &task->itk_lock_data;
 580
 581         kr = exception_deliver(self, exception, code, codeCnt, task->exc_actions, mutex);
 582
 583         if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 584                 return KERN_SUCCESS;
 585         }
 586         return KERN_FAILURE;
 587 }
 588
 589
 590 /*
 591  * Raise an exception on a task.
 592  * This should tell launchd to launch Crash Reporter for this task.
 593  */
 594 kern_return_t
 595 task_exception_notify(exception_type_t exception,
 596     mach_exception_data_type_t exccode, mach_exception_data_type_t excsubcode)
 597 {
 598         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 599         wait_interrupt_t                wsave;
 600         kern_return_t kr = KERN_SUCCESS;
 601
 602         code[0] = exccode;
 603         code[1] = excsubcode;
 604
 605         wsave = thread_interrupt_level(THREAD_UNINT);
 606         kr = exception_triage(exception, code, EXCEPTION_CODE_MAX);
 607         (void) thread_interrupt_level(wsave);
 608         return kr;
 609 }
 610
 611
 612 /*
 613  *      Handle interface for special performance monitoring
 614  *      This is a special case of the host exception handler
 615  */
 616 kern_return_t
 617 sys_perf_notify(thread_t thread, int pid)
 618 {
 619         host_priv_t             hostp;
 620         ipc_port_t              xport;
 621         wait_interrupt_t        wsave;
 622         kern_return_t           ret;
 623
 624         hostp = host_priv_self();       /* Get the host privileged ports */
 625         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 626         code[0] = 0xFF000001;           /* Set terminate code */
 627         code[1] = pid;          /* Pass out the pid */
 628
 629         struct task *task = thread->task;
 630         xport = hostp->exc_actions[EXC_RPC_ALERT].port;
 631
 632         /* Make sure we're not catching our own exception */
 633         if (!IP_VALID(xport) ||
 634             !ip_active(xport) ||
 635             task->itk_space == xport->data.receiver) {
 636                 return KERN_FAILURE;
 637         }
 638
 639         wsave = thread_interrupt_level(THREAD_UNINT);
 640         ret = exception_deliver(
 641                 thread,
 642                 EXC_RPC_ALERT,
 643                 code,
 644                 2,
 645                 hostp->exc_actions,
 646                 &hostp->lock);
 647         (void)thread_interrupt_level(wsave);
 648
 649         return ret;
 650 }