osfmk/kern/exception.c

   1 /*
   2  * Copyright (c) 2000-2020 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/ipc_tt.h>
  80 #include <kern/task.h>
  81 #include <kern/thread.h>
  82 #include <kern/processor.h>
  83 #include <kern/sched.h>
  84 #include <kern/sched_prim.h>
  85 #include <kern/host.h>
  86 #include <kern/misc_protos.h>
  87 #include <kern/ux_handler.h>
  88
  89 #include <vm/vm_map.h>
  90
  91 #include <security/mac_mach_internal.h>
  92 #include <string.h>
  93
  94 #include <pexpert/pexpert.h>
  95
  96 bool panic_on_exception_triage = false;
  97
  98 unsigned long c_thr_exc_raise = 0;
  99 unsigned long c_thr_exc_raise_state = 0;
 100 unsigned long c_thr_exc_raise_state_id = 0;
 101 unsigned long c_tsk_exc_raise = 0;
 102 unsigned long c_tsk_exc_raise_state = 0;
 103 unsigned long c_tsk_exc_raise_state_id = 0;
 104
 105 /* forward declarations */
 106 kern_return_t exception_deliver(
 107         thread_t                thread,
 108         exception_type_t        exception,
 109         mach_exception_data_t   code,
 110         mach_msg_type_number_t  codeCnt,
 111         struct exception_action *excp,
 112         lck_mtx_t                       *mutex);
 113
 114 static kern_return_t
 115 check_exc_receiver_dependency(
 116         exception_type_t exception,
 117         struct exception_action *excp,
 118         lck_mtx_t *mutex);
 119
 120 #ifdef MACH_BSD
 121 kern_return_t bsd_exception(
 122         exception_type_t        exception,
 123         mach_exception_data_t   code,
 124         mach_msg_type_number_t  codeCnt);
 125 #endif /* MACH_BSD */
 126
 127 #if __has_feature(ptrauth_calls)
 128 extern int exit_with_pac_exception(
 129         void *proc,
 130         exception_type_t         exception,
 131         mach_exception_code_t    code,
 132         mach_exception_subcode_t subcode);
 133
 134 extern bool proc_is_traced(void *p);
 135 #endif /* __has_feature(ptrauth_calls) */
 136
 137 /*
 138  * Routine: exception_init
 139  * Purpose:
 140  *   Global initialization of state for exceptions.
 141  * Conditions:
 142  *   None.
 143  */
 144 void
 145 exception_init(void)
 146 {
 147         int tmp = 0;
 148
 149         if (PE_parse_boot_argn("-panic_on_exception_triage", &tmp, sizeof(tmp))) {
 150                 panic_on_exception_triage = true;
 151         }
 152 }
 153
 154 /*
 155  *      Routine:        exception_deliver
 156  *      Purpose:
 157  *              Make an upcall to the exception server provided.
 158  *      Conditions:
 159  *              Nothing locked and no resources held.
 160  *              Called from an exception context, so
 161  *              thread_exception_return and thread_kdb_return
 162  *              are possible.
 163  *      Returns:
 164  *              KERN_SUCCESS if the exception was handled
 165  */
 166 kern_return_t
 167 exception_deliver(
 168         thread_t                thread,
 169         exception_type_t        exception,
 170         mach_exception_data_t   code,
 171         mach_msg_type_number_t  codeCnt,
 172         struct exception_action *excp,
 173         lck_mtx_t                       *mutex)
 174 {
 175         ipc_port_t              exc_port = IPC_PORT_NULL;
 176         exception_data_type_t   small_code[EXCEPTION_CODE_MAX];
 177         int                     code64;
 178         int                     behavior;
 179         int                     flavor;
 180         kern_return_t           kr;
 181         task_t task;
 182         ipc_port_t thread_port = IPC_PORT_NULL, task_port = IPC_PORT_NULL;
 183
 184         /*
 185          *  Save work if we are terminating.
 186          *  Just go back to our AST handler.
 187          */
 188         if (!thread->active && !thread->inspection) {
 189                 return KERN_SUCCESS;
 190         }
 191
 192         /*
 193          * If there are no exception actions defined for this entity,
 194          * we can't deliver here.
 195          */
 196         if (excp == NULL) {
 197                 return KERN_FAILURE;
 198         }
 199
 200         assert(exception < EXC_TYPES_COUNT);
 201         if (exception >= EXC_TYPES_COUNT) {
 202                 return KERN_FAILURE;
 203         }
 204
 205         excp = &excp[exception];
 206
 207         /*
 208          * Snapshot the exception action data under lock for consistency.
 209          * Hold a reference to the port over the exception_raise_* calls
 210          * so it can't be destroyed.  This seems like overkill, but keeps
 211          * the port from disappearing between now and when
 212          * ipc_object_copyin_from_kernel is finally called.
 213          */
 214         lck_mtx_lock(mutex);
 215         exc_port = excp->port;
 216         if (!IP_VALID(exc_port)) {
 217                 lck_mtx_unlock(mutex);
 218                 return KERN_FAILURE;
 219         }
 220         ip_lock(exc_port);
 221         if (!ip_active(exc_port)) {
 222                 ip_unlock(exc_port);
 223                 lck_mtx_unlock(mutex);
 224                 return KERN_FAILURE;
 225         }
 226         ip_reference(exc_port);
 227         exc_port->ip_srights++;
 228         ip_unlock(exc_port);
 229
 230         flavor = excp->flavor;
 231         behavior = excp->behavior;
 232         lck_mtx_unlock(mutex);
 233
 234         code64 = (behavior & MACH_EXCEPTION_CODES);
 235         behavior &= ~MACH_EXCEPTION_MASK;
 236
 237         if (!code64) {
 238                 small_code[0] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[0]);
 239                 small_code[1] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[1]);
 240         }
 241
 242         task = thread->task;
 243
 244 #if CONFIG_MACF
 245         /* Now is a reasonably good time to check if the exception action is
 246          * permitted for this process, because after this point we will send
 247          * the message out almost certainly.
 248          * As with other failures, exception_triage_thread will go on
 249          * to the next level.
 250          */
 251
 252         /* The global exception-to-signal translation port is safe to be an exception handler. */
 253         if (is_ux_handler_port(exc_port) == FALSE &&
 254             mac_exc_action_check_exception_send(task, excp) != 0) {
 255                 kr = KERN_FAILURE;
 256                 goto out_release_right;
 257         }
 258 #endif
 259
 260         if (behavior != EXCEPTION_STATE) {
 261                 task_reference(task);
 262                 task_port = convert_task_to_port(task);
 263                 /* task ref consumed */
 264                 thread_reference(thread);
 265                 thread_port = convert_thread_to_port(thread);
 266                 /* thread ref consumed */
 267         }
 268
 269         switch (behavior) {
 270         case EXCEPTION_STATE: {
 271                 mach_msg_type_number_t state_cnt;
 272                 thread_state_data_t state;
 273
 274                 c_thr_exc_raise_state++;
 275                 state_cnt = _MachineStateCount[flavor];
 276                 kr = thread_getstatus_to_user(thread, flavor,
 277                     (thread_state_t)state,
 278                     &state_cnt);
 279                 if (kr == KERN_SUCCESS) {
 280                         if (code64) {
 281                                 kr = mach_exception_raise_state(exc_port,
 282                                     exception,
 283                                     code,
 284                                     codeCnt,
 285                                     &flavor,
 286                                     state, state_cnt,
 287                                     state, &state_cnt);
 288                         } else {
 289                                 kr = exception_raise_state(exc_port, exception,
 290                                     small_code,
 291                                     codeCnt,
 292                                     &flavor,
 293                                     state, state_cnt,
 294                                     state, &state_cnt);
 295                         }
 296                         if (kr == KERN_SUCCESS) {
 297                                 if (exception != EXC_CORPSE_NOTIFY) {
 298                                         kr = thread_setstatus_from_user(thread, flavor,
 299                                             (thread_state_t)state,
 300                                             state_cnt);
 301                                 }
 302                                 goto out_release_right;
 303                         }
 304                 }
 305
 306                 goto out_release_right;
 307         }
 308
 309         case EXCEPTION_DEFAULT:
 310                 c_thr_exc_raise++;
 311                 if (code64) {
 312                         kr = mach_exception_raise(exc_port,
 313                             thread_port,
 314                             task_port,
 315                             exception,
 316                             code,
 317                             codeCnt);
 318                 } else {
 319                         kr = exception_raise(exc_port,
 320                             thread_port,
 321                             task_port,
 322                             exception,
 323                             small_code,
 324                             codeCnt);
 325                 }
 326
 327                 goto out_release_right;
 328
 329         case EXCEPTION_STATE_IDENTITY: {
 330                 mach_msg_type_number_t state_cnt;
 331                 thread_state_data_t state;
 332
 333                 c_thr_exc_raise_state_id++;
 334                 state_cnt = _MachineStateCount[flavor];
 335                 kr = thread_getstatus_to_user(thread, flavor,
 336                     (thread_state_t)state,
 337                     &state_cnt);
 338                 if (kr == KERN_SUCCESS) {
 339                         if (code64) {
 340                                 kr = mach_exception_raise_state_identity(
 341                                         exc_port,
 342                                         thread_port,
 343                                         task_port,
 344                                         exception,
 345                                         code,
 346                                         codeCnt,
 347                                         &flavor,
 348                                         state, state_cnt,
 349                                         state, &state_cnt);
 350                         } else {
 351                                 kr = exception_raise_state_identity(exc_port,
 352                                     thread_port,
 353                                     task_port,
 354                                     exception,
 355                                     small_code,
 356                                     codeCnt,
 357                                     &flavor,
 358                                     state, state_cnt,
 359                                     state, &state_cnt);
 360                         }
 361
 362                         if (kr == KERN_SUCCESS) {
 363                                 if (exception != EXC_CORPSE_NOTIFY) {
 364                                         kr = thread_setstatus_from_user(thread, flavor,
 365                                             (thread_state_t)state,
 366                                             state_cnt);
 367                                 }
 368                                 goto out_release_right;
 369                         }
 370                 }
 371
 372                 goto out_release_right;
 373         }
 374
 375         default:
 376                 panic("bad exception behavior!");
 377                 return KERN_FAILURE;
 378         }/* switch */
 379
 380 out_release_right:
 381
 382         if (task_port) {
 383                 ipc_port_release_send(task_port);
 384         }
 385
 386         if (thread_port) {
 387                 ipc_port_release_send(thread_port);
 388         }
 389
 390         if (exc_port) {
 391                 ipc_port_release_send(exc_port);
 392         }
 393
 394         return kr;
 395 }
 396
 397 /*
 398  * Routine: check_exc_receiver_dependency
 399  * Purpose:
 400  *      Verify that the port destined for receiving this exception is not
 401  *      on the current task. This would cause hang in kernel for
 402  *      EXC_CRASH primarily. Note: If port is transferred
 403  *      between check and delivery then deadlock may happen.
 404  *
 405  * Conditions:
 406  *              Nothing locked and no resources held.
 407  *              Called from an exception context.
 408  * Returns:
 409  *      KERN_SUCCESS if its ok to send exception message.
 410  */
 411 kern_return_t
 412 check_exc_receiver_dependency(
 413         exception_type_t exception,
 414         struct exception_action *excp,
 415         lck_mtx_t *mutex)
 416 {
 417         kern_return_t retval = KERN_SUCCESS;
 418
 419         if (excp == NULL || exception != EXC_CRASH) {
 420                 return retval;
 421         }
 422
 423         task_t task = current_task();
 424         lck_mtx_lock(mutex);
 425         ipc_port_t xport = excp[exception].port;
 426         if (IP_VALID(xport)
 427             && ip_active(xport)
 428             && task->itk_space == xport->ip_receiver) {
 429                 retval = KERN_FAILURE;
 430         }
 431         lck_mtx_unlock(mutex);
 432         return retval;
 433 }
 434
 435
 436 /*
 437  *      Routine:        exception_triage_thread
 438  *      Purpose:
 439  *              The thread caught an exception.
 440  *              We make an up-call to the thread's exception server.
 441  *      Conditions:
 442  *              Nothing locked and no resources held.
 443  *              Called from an exception context, so
 444  *              thread_exception_return and thread_kdb_return
 445  *              are possible.
 446  *      Returns:
 447  *              KERN_SUCCESS if exception is handled by any of the handlers.
 448  */
 449 kern_return_t
 450 exception_triage_thread(
 451         exception_type_t        exception,
 452         mach_exception_data_t   code,
 453         mach_msg_type_number_t  codeCnt,
 454         thread_t                thread)
 455 {
 456         task_t                  task;
 457         host_priv_t             host_priv;
 458         lck_mtx_t               *mutex;
 459         kern_return_t   kr = KERN_FAILURE;
 460
 461
 462         assert(exception != EXC_RPC_ALERT);
 463
 464         /*
 465          * If this behavior has been requested by the the kernel
 466          * (due to the boot environment), we should panic if we
 467          * enter this function.  This is intended as a debugging
 468          * aid; it should allow us to debug why we caught an
 469          * exception in environments where debugging is especially
 470          * difficult.
 471          */
 472         if (panic_on_exception_triage) {
 473                 panic("called exception_triage when it was forbidden by the boot environment");
 474         }
 475
 476         /*
 477          * Try to raise the exception at the activation level.
 478          */
 479         mutex = &thread->mutex;
 480         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, thread->exc_actions, mutex)) {
 481                 kr = exception_deliver(thread, exception, code, codeCnt, thread->exc_actions, mutex);
 482                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 483                         goto out;
 484                 }
 485         }
 486
 487         /*
 488          * Maybe the task level will handle it.
 489          */
 490         task = thread->task;
 491         mutex = &task->itk_lock_data;
 492         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, task->exc_actions, mutex)) {
 493                 kr = exception_deliver(thread, exception, code, codeCnt, task->exc_actions, mutex);
 494                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 495                         goto out;
 496                 }
 497         }
 498
 499         /*
 500          * How about at the host level?
 501          */
 502         host_priv = host_priv_self();
 503         mutex = &host_priv->lock;
 504
 505         if (KERN_SUCCESS == check_exc_receiver_dependency(exception, host_priv->exc_actions, mutex)) {
 506                 kr = exception_deliver(thread, exception, code, codeCnt, host_priv->exc_actions, mutex);
 507                 if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 508                         goto out;
 509                 }
 510         }
 511
 512 out:
 513         if ((exception != EXC_CRASH) && (exception != EXC_RESOURCE) &&
 514             (exception != EXC_GUARD) && (exception != EXC_CORPSE_NOTIFY)) {
 515                 thread_exception_return();
 516         }
 517         return kr;
 518 }
 519
 520 /*
 521  *      Routine:        exception_triage
 522  *      Purpose:
 523  *              The current thread caught an exception.
 524  *              We make an up-call to the thread's exception server.
 525  *      Conditions:
 526  *              Nothing locked and no resources held.
 527  *              Called from an exception context, so
 528  *              thread_exception_return and thread_kdb_return
 529  *              are possible.
 530  *      Returns:
 531  *              KERN_SUCCESS if exception is handled by any of the handlers.
 532  */
 533 int debug4k_panic_on_exception = 0;
 534 kern_return_t
 535 exception_triage(
 536         exception_type_t        exception,
 537         mach_exception_data_t   code,
 538         mach_msg_type_number_t  codeCnt)
 539 {
 540         thread_t thread = current_thread();
 541         if (VM_MAP_PAGE_SIZE(thread->task->map) < PAGE_SIZE) {
 542                 DEBUG4K_EXC("thread %p task %p map %p exception %d codes 0x%llx 0x%llx \n", thread, thread->task, thread->task->map, exception, code[0], code[1]);
 543                 if (debug4k_panic_on_exception) {
 544                         panic("DEBUG4K %s:%d thread %p task %p map %p exception %d codes 0x%llx 0x%llx \n", __FUNCTION__, __LINE__, thread, thread->task, thread->task->map, exception, code[0], code[1]);
 545                 }
 546         }
 547 #if __has_feature(ptrauth_calls)
 548         /*
 549          * If it is a ptrauth violation, then check if the task has the TF_PAC_EXC_FATAL
 550          * flag set and isn't being ptraced. If so, terminate the task via exit_with_reason
 551          */
 552         if (exception & EXC_PTRAUTH_BIT) {
 553                 exception &= ~EXC_PTRAUTH_BIT;
 554
 555                 boolean_t traced_flag = FALSE;
 556                 task_t task = thread->task;
 557                 void *proc = task->bsd_info;
 558
 559                 if (task->bsd_info) {
 560                         traced_flag = proc_is_traced(proc);
 561                 }
 562
 563                 if (task_is_pac_exception_fatal(current_task()) && !traced_flag) {
 564                         exit_with_pac_exception(proc, exception, code[0], code[1]);
 565                         thread_exception_return();
 566                         /* NOT_REACHABLE */
 567                 }
 568         }
 569 #endif /* __has_feature(ptrauth_calls) */
 570         return exception_triage_thread(exception, code, codeCnt, thread);
 571 }
 572
 573 kern_return_t
 574 bsd_exception(
 575         exception_type_t        exception,
 576         mach_exception_data_t   code,
 577         mach_msg_type_number_t  codeCnt)
 578 {
 579         task_t                  task;
 580         lck_mtx_t               *mutex;
 581         thread_t                self = current_thread();
 582         kern_return_t           kr;
 583
 584         /*
 585          * Maybe the task level will handle it.
 586          */
 587         task = current_task();
 588         mutex = &task->itk_lock_data;
 589
 590         kr = exception_deliver(self, exception, code, codeCnt, task->exc_actions, mutex);
 591
 592         if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED) {
 593                 return KERN_SUCCESS;
 594         }
 595         return KERN_FAILURE;
 596 }
 597
 598
 599 /*
 600  * Raise an exception on a task.
 601  * This should tell launchd to launch Crash Reporter for this task.
 602  */
 603 kern_return_t
 604 task_exception_notify(exception_type_t exception,
 605     mach_exception_data_type_t exccode, mach_exception_data_type_t excsubcode)
 606 {
 607         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 608         wait_interrupt_t                wsave;
 609         kern_return_t kr = KERN_SUCCESS;
 610
 611         code[0] = exccode;
 612         code[1] = excsubcode;
 613
 614         wsave = thread_interrupt_level(THREAD_UNINT);
 615         kr = exception_triage(exception, code, EXCEPTION_CODE_MAX);
 616         (void) thread_interrupt_level(wsave);
 617         return kr;
 618 }
 619
 620
 621 /*
 622  *      Handle interface for special performance monitoring
 623  *      This is a special case of the host exception handler
 624  */
 625 kern_return_t
 626 sys_perf_notify(thread_t thread, int pid)
 627 {
 628         host_priv_t             hostp;
 629         ipc_port_t              xport;
 630         wait_interrupt_t        wsave;
 631         kern_return_t           ret;
 632
 633         hostp = host_priv_self();       /* Get the host privileged ports */
 634         mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
 635         code[0] = 0xFF000001;           /* Set terminate code */
 636         code[1] = pid;          /* Pass out the pid */
 637
 638         struct task *task = thread->task;
 639         xport = hostp->exc_actions[EXC_RPC_ALERT].port;
 640
 641         /* Make sure we're not catching our own exception */
 642         if (!IP_VALID(xport) ||
 643             !ip_active(xport) ||
 644             task->itk_space == xport->data.receiver) {
 645                 return KERN_FAILURE;
 646         }
 647
 648         wsave = thread_interrupt_level(THREAD_UNINT);
 649         ret = exception_deliver(
 650                 thread,
 651                 EXC_RPC_ALERT,
 652                 code,
 653                 2,
 654                 hostp->exc_actions,
 655                 &hostp->lock);
 656         (void)thread_interrupt_level(wsave);
 657
 658         return ret;
 659 }