1 /*
2 * Copyright (c) 2012-2013, 2015 Apple 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
30 /*
31 * Corpses Overview
32 * ================
33 *
34 * A corpse is a state of process that is past the point of its death. This means that process has
35 * completed all its termination operations like releasing file descriptors, mach ports, sockets and
36 * other constructs used to identify a process. For all the processes this mimics the behavior as if
37 * the process has died and no longer available by any means.
38 *
39 * Why do we need Corpses?
40 * -----------------------
41 * For crash inspection we need to inspect the state and data that is associated with process so that
42 * crash reporting infrastructure can build backtraces, find leaks etc. For example a crash
43 *
44 * Corpses functionality in kernel
45 * ===============================
46 * The corpse functionality is an extension of existing exception reporting mechanisms we have. The
47 * exception_triage calls will try to deliver the first round of exceptions allowing
48 * task/debugger/ReportCrash/launchd level exception handlers to respond to exception. If even after
49 * notification the exception is not handled, then the process begins the death operations and during
50 * proc_prepareexit, we decide to create a corpse for inspection. Following is a sample run through
51 * of events and data shuffling that happens when corpses is enabled.
52 *
53 * * a process causes an exception during normal execution of threads.
54 * * The exception generated by either mach(e.g GUARDED_MARCHPORT) or bsd(eg SIGABORT, GUARDED_FD
55 * etc) side is passed through the exception_triage() function to follow the thread -> task -> host
56 * level exception handling system. This set of steps are same as before and allow for existing
57 * crash reporting systems (both internal and 3rd party) to catch and create reports as required.
58 * * If above exception handling returns failed (when nobody handles the notification), then the
59 * proc_prepareexit path has logic to decide to create corpse.
60 * * The task_mark_corpse function allocates userspace vm memory and attaches the information
61 * kcdata_descriptor_t to task->corpse_info field of task.
62 * - All the task's threads are marked with the "inspection" flag which signals the termination
63 * daemon to not reap them but hold until they are being inspected.
64 * - task flags t_flags reflect the corpse bit and also a PENDING_CORPSE bit. PENDING_CORPSE
65 * prevents task_terminate from stripping important data from task.
66 * - It marks all the threads to terminate and return to AST for termination.
67 * - The allocation logic takes into account the rate limiting policy of allowing only
68 * TOTAL_CORPSES_ALLOWED in flight.
69 * * The proc exit threads continues and collects required information in the allocated vm region.
70 * Once complete it marks itself for termination.
71 * * In the thread_terminate_self(), the last thread to enter will do a call to proc_exit().
72 * Following this is a check to see if task is marked for corpse notification and will
73 * invoke the the task_deliver_crash_notification().
74 * * Once EXC_CORPSE_NOTIFY is delivered, it removes the PENDING_CORPSE flag from task (and
75 * inspection flag from all its threads) and allows task_terminate to go ahead and continue
76 * the mach task termination process.
77 * * ASIDE: The rest of the threads that are reaching the thread_terminate_daemon() with the
78 * inspection flag set are just bounced to another holding queue (crashed_threads_queue).
79 * Only after the corpse notification these are pulled out from holding queue and enqueued
80 * back to termination queue
81 *
82 *
83 * Corpse info format
84 * ==================
85 * The kernel (task_mark_corpse()) makes a vm allocation in the dead task's vm space (with tag
86 * VM_MEMORY_CORPSEINFO (80)). Within this memory all corpse information is saved by various
87 * subsystems like
88 * * bsd proc exit path may write down pid, parent pid, number of file descriptors etc
89 * * mach side may append data regarding ledger usage, memory stats etc
90 * See detailed info about the memory structure and format in kern_cdata.h documentation.
91 *
92 * Configuring Corpses functionality
93 * =================================
94 * boot-arg: -no_corpses disables the corpse generation. This can be added/removed without affecting
95 * any other subsystem.
96 * TOTAL_CORPSES_ALLOWED : (recompilation required) - Changing this number allows for controlling
97 * the number of corpse instances to be held for inspection before allowing memory to be reclaimed
98 * by system.
99 * CORPSEINFO_ALLOCATION_SIZE: is the default size of vm allocation. If in future there is much more
100 * data to be put in, then please re-tune this parameter.
101 *
102 * Debugging/Visibility
103 * ====================
104 * * lldbmacros for thread and task summary are updated to show "C" flag for corpse task/threads.
105 * * there are macros to see list of threads in termination queue (dumpthread_terminate_queue)
106 * and holding queue (dumpcrashed_thread_queue).
107 * * In case of corpse creation is disabled of ignored then the system log is updated with
108 * printf data with reason.
109 *
110 * Limitations of Corpses
111 * ======================
112 * With holding off memory for inspection, it creates vm pressure which might not be desirable
113 * on low memory devices. There are limits to max corpses being inspected at a time which is
114 * marked by TOTAL_CORPSES_ALLOWED.
115 *
116 */
117
118
119 #include <stdatomic.h>
120 #include <kern/assert.h>
121 #include <mach/mach_types.h>
122 #include <mach/boolean.h>
123 #include <mach/vm_param.h>
124 #include <mach/task.h>
125 #include <mach/thread_act.h>
126 #include <mach/host_priv.h>
127 #include <kern/host.h>
128 #include <kern/kern_types.h>
129 #include <kern/mach_param.h>
130 #include <kern/thread.h>
131 #include <kern/task.h>
132 #include <corpses/task_corpse.h>
133 #include <kern/kalloc.h>
134 #include <kern/kern_cdata.h>
135 #include <mach/mach_vm.h>
136 #include <kern/exc_guard.h>
137 #include <os/log.h>
138
139 #if CONFIG_MACF
140 #include <security/mac_mach_internal.h>
141 #endif
142
143 /*
144 * Exported interfaces
145 */
146 #include <mach/task_server.h>
147
148 union corpse_creation_gate {
149 struct {
150 uint16_t user_faults;
151 uint16_t corpses;
152 };
153 uint32_t value;
154 };
155
156 static _Atomic uint32_t inflight_corpses;
157 unsigned long total_corpses_created = 0;
158
159 static TUNABLE(bool, corpses_disabled, "-no_corpses", false);
160
161 #if !XNU_TARGET_OS_OSX
162 /* Use lightweight corpse on embedded */
163 static TUNABLE(bool, lw_corpses_enabled, "lw_corpses", true);
164 #else
165 static TUNABLE(bool, lw_corpses_enabled, "lw_corpses", false);
166 #endif
167
168 #if DEBUG || DEVELOPMENT
169 /* bootarg to generate corpse with size up to max_footprint_mb */
170 TUNABLE(bool, corpse_threshold_system_limit, "corpse_threshold_system_limit", false);
171 #endif /* DEBUG || DEVELOPMENT */
172
173 /* bootarg to turn on corpse forking for EXC_RESOURCE */
174 TUNABLE(bool, exc_via_corpse_forking, "exc_via_corpse_forking", true);
175
176 /* bootarg to generate corpse for fatal high memory watermark violation */
177 TUNABLE(bool, corpse_for_fatal_memkill, "corpse_for_fatal_memkill", true);
178
179 extern int IS_64BIT_PROCESS(void *);
180 extern void gather_populate_corpse_crashinfo(void *p, task_t task,
181 mach_exception_data_type_t code, mach_exception_data_type_t subcode,
182 uint64_t *udata_buffer, int num_udata, void *reason, exception_type_t etype);
183 extern void *proc_find(int pid);
184 extern int proc_rele(void *p);
185 extern task_t proc_get_task_raw(void *proc);
186 extern char *proc_best_name(struct proc *proc);
187
188
189 /*
190 * Routine: corpses_enabled
191 * returns FALSE if not enabled
192 */
193 boolean_t
corpses_enabled(void)194 corpses_enabled(void)
195 {
196 return !corpses_disabled;
197 }
198
199 unsigned long
total_corpses_count(void)200 total_corpses_count(void)
201 {
202 union corpse_creation_gate gate;
203
204 gate.value = atomic_load_explicit(&inflight_corpses, memory_order_relaxed);
205 return gate.corpses;
206 }
207
208 extern char *proc_best_name(struct proc *);
209 extern int proc_pid(struct proc *);
210
211 /*
212 * Routine: task_crashinfo_get_ref()
213 * Grab a slot at creating a corpse.
214 * Returns: KERN_SUCCESS if the policy allows for creating a corpse.
215 */
216 static kern_return_t
task_crashinfo_get_ref(corpse_flags_t kcd_u_flags)217 task_crashinfo_get_ref(corpse_flags_t kcd_u_flags)
218 {
219 union corpse_creation_gate oldgate, newgate;
220 struct proc *p = (void *)current_proc();
221
222 assert(kcd_u_flags & CORPSE_CRASHINFO_HAS_REF);
223
224 oldgate.value = atomic_load_explicit(&inflight_corpses, memory_order_relaxed);
225 for (;;) {
226 newgate = oldgate;
227 if (kcd_u_flags & CORPSE_CRASHINFO_USER_FAULT) {
228 if (newgate.user_faults++ >= TOTAL_USER_FAULTS_ALLOWED) {
229 os_log(OS_LOG_DEFAULT, "%s[%d] Corpse failure, too many faults %d\n",
230 proc_best_name(p), proc_pid(p), newgate.user_faults);
231 return KERN_RESOURCE_SHORTAGE;
232 }
233 }
234 if (newgate.corpses++ >= TOTAL_CORPSES_ALLOWED) {
235 os_log(OS_LOG_DEFAULT, "%s[%d] Corpse failure, too many %d\n",
236 proc_best_name(p), proc_pid(p), newgate.corpses);
237 return KERN_RESOURCE_SHORTAGE;
238 }
239
240 // this reloads the value in oldgate
241 if (atomic_compare_exchange_strong_explicit(&inflight_corpses,
242 &oldgate.value, newgate.value, memory_order_relaxed,
243 memory_order_relaxed)) {
244 os_log(OS_LOG_DEFAULT, "%s[%d] Corpse allowed %d of %d\n",
245 proc_best_name(p), proc_pid(p), newgate.corpses, TOTAL_CORPSES_ALLOWED);
246 return KERN_SUCCESS;
247 }
248 }
249 }
250
251 /*
252 * Routine: task_crashinfo_release_ref
253 * release the slot for corpse being used.
254 */
255 static kern_return_t
task_crashinfo_release_ref(corpse_flags_t kcd_u_flags)256 task_crashinfo_release_ref(corpse_flags_t kcd_u_flags)
257 {
258 union corpse_creation_gate oldgate, newgate;
259
260 assert(kcd_u_flags & CORPSE_CRASHINFO_HAS_REF);
261
262 oldgate.value = atomic_load_explicit(&inflight_corpses, memory_order_relaxed);
263 for (;;) {
264 newgate = oldgate;
265 if (kcd_u_flags & CORPSE_CRASHINFO_USER_FAULT) {
266 if (newgate.user_faults-- == 0) {
267 panic("corpse in flight count over-release");
268 }
269 }
270 if (newgate.corpses-- == 0) {
271 panic("corpse in flight count over-release");
272 }
273 // this reloads the value in oldgate
274 if (atomic_compare_exchange_strong_explicit(&inflight_corpses,
275 &oldgate.value, newgate.value, memory_order_relaxed,
276 memory_order_relaxed)) {
277 os_log(OS_LOG_DEFAULT, "Corpse released, count at %d\n", newgate.corpses);
278 return KERN_SUCCESS;
279 }
280 }
281 }
282
283
284 kcdata_descriptor_t
task_crashinfo_alloc_init(mach_vm_address_t crash_data_p,unsigned size,corpse_flags_t kc_u_flags,unsigned kc_flags)285 task_crashinfo_alloc_init(mach_vm_address_t crash_data_p, unsigned size,
286 corpse_flags_t kc_u_flags, unsigned kc_flags)
287 {
288 kcdata_descriptor_t kcdata;
289
290 if (kc_u_flags & CORPSE_CRASHINFO_HAS_REF) {
291 if (KERN_SUCCESS != task_crashinfo_get_ref(kc_u_flags)) {
292 return NULL;
293 }
294 }
295
296 kcdata = kcdata_memory_alloc_init(crash_data_p, TASK_CRASHINFO_BEGIN, size,
297 kc_flags);
298 if (kcdata) {
299 kcdata->kcd_user_flags = kc_u_flags;
300 } else if (kc_u_flags & CORPSE_CRASHINFO_HAS_REF) {
301 task_crashinfo_release_ref(kc_u_flags);
302 }
303 return kcdata;
304 }
305
306 kcdata_descriptor_t
task_btinfo_alloc_init(mach_vm_address_t addr,unsigned size)307 task_btinfo_alloc_init(mach_vm_address_t addr, unsigned size)
308 {
309 kcdata_descriptor_t kcdata;
310
311 kcdata = kcdata_memory_alloc_init(addr, TASK_BTINFO_BEGIN, size, KCFLAG_USE_MEMCOPY);
312
313 return kcdata;
314 }
315
316
317 /*
318 * Free up the memory associated with task_crashinfo_data
319 */
320 kern_return_t
task_crashinfo_destroy(kcdata_descriptor_t data)321 task_crashinfo_destroy(kcdata_descriptor_t data)
322 {
323 if (!data) {
324 return KERN_INVALID_ARGUMENT;
325 }
326 if (data->kcd_user_flags & CORPSE_CRASHINFO_HAS_REF) {
327 task_crashinfo_release_ref(data->kcd_user_flags);
328 }
329 return kcdata_memory_destroy(data);
330 }
331
332 /*
333 * Routine: task_get_corpseinfo
334 * params: task - task which has corpse info setup.
335 * returns: crash info data attached to task.
336 * NULL if task is null or has no corpse info
337 */
338 kcdata_descriptor_t
task_get_corpseinfo(task_t task)339 task_get_corpseinfo(task_t task)
340 {
341 kcdata_descriptor_t retval = NULL;
342 if (task != NULL) {
343 retval = task->corpse_info;
344 }
345 return retval;
346 }
347
348 /*
349 * Routine: task_add_to_corpse_task_list
350 * params: task - task to be added to corpse task list
351 * returns: None.
352 */
353 void
task_add_to_corpse_task_list(task_t corpse_task)354 task_add_to_corpse_task_list(task_t corpse_task)
355 {
356 lck_mtx_lock(&tasks_corpse_lock);
357 queue_enter(&corpse_tasks, corpse_task, task_t, corpse_tasks);
358 lck_mtx_unlock(&tasks_corpse_lock);
359 }
360
361 /*
362 * Routine: task_remove_from_corpse_task_list
363 * params: task - task to be removed from corpse task list
364 * returns: None.
365 */
366 void
task_remove_from_corpse_task_list(task_t corpse_task)367 task_remove_from_corpse_task_list(task_t corpse_task)
368 {
369 lck_mtx_lock(&tasks_corpse_lock);
370 queue_remove(&corpse_tasks, corpse_task, task_t, corpse_tasks);
371 lck_mtx_unlock(&tasks_corpse_lock);
372 }
373
374 /*
375 * Routine: task_purge_all_corpses
376 * params: None.
377 * returns: None.
378 */
379 void
task_purge_all_corpses(void)380 task_purge_all_corpses(void)
381 {
382 task_t task;
383
384 lck_mtx_lock(&tasks_corpse_lock);
385 /* Iterate through all the corpse tasks and clear all map entries */
386 queue_iterate(&corpse_tasks, task, task_t, corpse_tasks) {
387 os_log(OS_LOG_DEFAULT, "Memory pressure corpse purge for pid %d.\n", task_pid(task));
388 vm_map_terminate(task->map);
389 }
390 lck_mtx_unlock(&tasks_corpse_lock);
391 }
392
393 /*
394 * Routine: find_corpse_task_by_uniqueid_grp
395 * params: task_uniqueid - uniqueid of the corpse
396 * target - target task [Out Param]
397 * grp - task reference group
398 * returns:
399 * KERN_SUCCESS if a matching corpse if found, gives a ref.
400 * KERN_FAILURE corpse with given uniqueid is not found.
401 */
402 kern_return_t
find_corpse_task_by_uniqueid_grp(uint64_t task_uniqueid,task_t * target,task_grp_t grp)403 find_corpse_task_by_uniqueid_grp(
404 uint64_t task_uniqueid,
405 task_t *target,
406 task_grp_t grp)
407 {
408 task_t task;
409
410 lck_mtx_lock(&tasks_corpse_lock);
411
412 queue_iterate(&corpse_tasks, task, task_t, corpse_tasks) {
413 if (task->task_uniqueid == task_uniqueid) {
414 lck_mtx_unlock(&tasks_corpse_lock);
415 task_reference_grp(task, grp);
416 *target = task;
417 return KERN_SUCCESS;
418 }
419 }
420
421 lck_mtx_unlock(&tasks_corpse_lock);
422 return KERN_FAILURE;
423 }
424
425 /*
426 * Routine: task_generate_corpse
427 * params: task - task to fork a corpse
428 * corpse_task - task port of the generated corpse
429 * returns: KERN_SUCCESS on Success.
430 * KERN_FAILURE on Failure.
431 * KERN_NOT_SUPPORTED on corpse disabled.
432 * KERN_RESOURCE_SHORTAGE on memory alloc failure or reaching max corpse.
433 */
434 kern_return_t
task_generate_corpse(task_t task,ipc_port_t * corpse_task_port)435 task_generate_corpse(
436 task_t task,
437 ipc_port_t *corpse_task_port)
438 {
439 task_t new_task;
440 kern_return_t kr;
441 thread_t thread, th_iter;
442 ipc_port_t corpse_port;
443
444 if (task == kernel_task || task == TASK_NULL) {
445 return KERN_INVALID_ARGUMENT;
446 }
447
448 task_lock(task);
449 if (task_is_a_corpse_fork(task)) {
450 task_unlock(task);
451 return KERN_INVALID_ARGUMENT;
452 }
453 task_unlock(task);
454
455 /* Generate a corpse for the given task, will return with a ref on corpse task */
456 kr = task_generate_corpse_internal(task, &new_task, &thread, 0, 0, 0, NULL);
457 if (kr != KERN_SUCCESS) {
458 return kr;
459 }
460 if (thread != THREAD_NULL) {
461 thread_deallocate(thread);
462 }
463
464 /* wait for all the threads in the task to terminate */
465 task_lock(new_task);
466 task_wait_till_threads_terminate_locked(new_task);
467
468 /* Reset thread ports of all the threads in task */
469 queue_iterate(&new_task->threads, th_iter, thread_t, task_threads)
470 {
471 /* Do not reset the thread port for inactive threads */
472 if (th_iter->corpse_dup == FALSE) {
473 ipc_thread_reset(th_iter);
474 }
475 }
476 task_unlock(new_task);
477
478 /* transfer the task ref to port and arm the no-senders notification */
479 corpse_port = convert_corpse_to_port_and_nsrequest(new_task);
480 assert(IP_NULL != corpse_port);
481
482 *corpse_task_port = corpse_port;
483 return KERN_SUCCESS;
484 }
485
486 /*
487 * Only generate lightweight corpse if any of thread, task, or host level registers
488 * EXC_CORPSE_NOTIFY with behavior EXCEPTION_BACKTRACE.
489 *
490 * Save a send right and behavior of those ports on out param EXC_PORTS.
491 */
492 static boolean_t
task_should_generate_lightweight_corpse(task_t task,ipc_port_t exc_ports[static BT_EXC_PORTS_COUNT])493 task_should_generate_lightweight_corpse(
494 task_t task,
495 ipc_port_t exc_ports[static BT_EXC_PORTS_COUNT])
496 {
497 kern_return_t kr;
498 boolean_t should_generate = FALSE;
499
500 exception_mask_t mask;
501 mach_msg_type_number_t nmasks;
502 exception_port_t exc_port = IP_NULL;
503 exception_behavior_t behavior;
504 thread_state_flavor_t flavor;
505
506 if (task != current_task()) {
507 return FALSE;
508 }
509
510 if (!lw_corpses_enabled) {
511 return FALSE;
512 }
513
514 for (unsigned int i = 0; i < BT_EXC_PORTS_COUNT; i++) {
515 nmasks = 1;
516
517 /* thread, task, and host level, in this order */
518 if (i == 0) {
519 kr = thread_get_exception_ports(current_thread(), EXC_MASK_CORPSE_NOTIFY,
520 &mask, &nmasks, &exc_port, &behavior, &flavor);
521 } else if (i == 1) {
522 kr = task_get_exception_ports(current_task(), EXC_MASK_CORPSE_NOTIFY,
523 &mask, &nmasks, &exc_port, &behavior, &flavor);
524 } else {
525 kr = host_get_exception_ports(host_priv_self(), EXC_MASK_CORPSE_NOTIFY,
526 &mask, &nmasks, &exc_port, &behavior, &flavor);
527 }
528
529 if (kr != KERN_SUCCESS || nmasks == 0) {
530 exc_port = IP_NULL;
531 }
532
533 /* thread level can return KERN_SUCCESS && nmasks 0 */
534 assert(nmasks == 1 || i == 0);
535
536 if (IP_VALID(exc_port) && (behavior & MACH_EXCEPTION_BACKTRACE_PREFERRED)) {
537 assert(behavior & MACH_EXCEPTION_CODES);
538 exc_ports[i] = exc_port; /* transfers right to array */
539 exc_port = NULL;
540 should_generate = TRUE;
541 } else {
542 exc_ports[i] = IP_NULL;
543 }
544
545 ipc_port_release_send(exc_port);
546 }
547
548 return should_generate;
549 }
550
551 /*
552 * Routine: task_enqueue_exception_with_corpse
553 * params: task - task to generate a corpse and enqueue it
554 * etype - EXC_RESOURCE or EXC_GUARD
555 * code - exception code to be enqueued
556 * codeCnt - code array count - code and subcode
557 *
558 * returns: KERN_SUCCESS on Success.
559 * KERN_FAILURE on Failure.
560 * KERN_INVALID_ARGUMENT on invalid arguments passed.
561 * KERN_NOT_SUPPORTED on corpse disabled.
562 * KERN_RESOURCE_SHORTAGE on memory alloc failure or reaching max corpse.
563 */
564 kern_return_t
task_enqueue_exception_with_corpse(task_t task,exception_type_t etype,mach_exception_data_t code,mach_msg_type_number_t codeCnt,void * reason,boolean_t lightweight)565 task_enqueue_exception_with_corpse(
566 task_t task,
567 exception_type_t etype,
568 mach_exception_data_t code,
569 mach_msg_type_number_t codeCnt,
570 void *reason,
571 boolean_t lightweight)
572 {
573 kern_return_t kr;
574 ipc_port_t exc_ports[BT_EXC_PORTS_COUNT]; /* send rights in thread, task, host order */
575 const char *procname = proc_best_name(get_bsdtask_info(task));
576
577 if (codeCnt < 2) {
578 return KERN_INVALID_ARGUMENT;
579 }
580
581 if (lightweight && task_should_generate_lightweight_corpse(task, exc_ports)) {
582 /* port rights captured in exc_ports */
583 kcdata_descriptor_t desc = NULL;
584 kcdata_object_t obj = KCDATA_OBJECT_NULL;
585 bool lw_corpse_enqueued = false;
586
587 assert(task == current_task());
588 assert(etype == EXC_GUARD);
589
590 kr = kcdata_object_throttle_get(KCDATA_OBJECT_TYPE_LW_CORPSE);
591 if (kr != KERN_SUCCESS) {
592 goto out;
593 }
594
595 kr = current_thread_collect_backtrace_info(&desc, etype, code, codeCnt, reason);
596 if (kr != KERN_SUCCESS) {
597 kcdata_object_throttle_release(KCDATA_OBJECT_TYPE_LW_CORPSE);
598 goto out;
599 }
600
601 kr = kcdata_create_object(desc, KCDATA_OBJECT_TYPE_LW_CORPSE, BTINFO_ALLOCATION_SIZE, &obj);
602 assert(kr == KERN_SUCCESS);
603 /* desc ref and throttle slot captured in obj ref */
604
605 thread_backtrace_enqueue(obj, exc_ports, etype);
606 os_log(OS_LOG_DEFAULT, "Lightweight corpse enqueued for %s\n", procname);
607 /* obj ref and exc_ports send rights consumed */
608 lw_corpse_enqueued = true;
609
610 out:
611 if (!lw_corpse_enqueued) {
612 for (unsigned int i = 0; i < BT_EXC_PORTS_COUNT; i++) {
613 ipc_port_release_send(exc_ports[i]);
614 }
615 }
616 } else {
617 task_t corpse = TASK_NULL;
618 thread_t thread = THREAD_NULL;
619
620 /* Generate a corpse for the given task, will return with a ref on corpse task */
621 kr = task_generate_corpse_internal(task, &corpse, &thread, etype,
622 code[0], code[1], reason);
623 if (kr == KERN_SUCCESS) {
624 if (thread == THREAD_NULL) {
625 return KERN_FAILURE;
626 }
627 assert(corpse != TASK_NULL);
628 assert(etype == EXC_RESOURCE || etype == EXC_GUARD);
629 thread_exception_enqueue(corpse, thread, etype);
630 os_log(OS_LOG_DEFAULT, "Full corpse enqueued for %s\n", procname);
631 }
632 }
633
634 return kr;
635 }
636
637 /*
638 * Routine: task_generate_corpse_internal
639 * params: task - task to fork a corpse
640 * corpse_task - task of the generated corpse
641 * exc_thread - equivalent thread in corpse enqueuing exception
642 * etype - EXC_RESOURCE or EXC_GUARD or 0
643 * code - mach exception code to be passed in corpse blob
644 * subcode - mach exception subcode to be passed in corpse blob
645 * returns: KERN_SUCCESS on Success.
646 * KERN_FAILURE on Failure.
647 * KERN_NOT_SUPPORTED on corpse disabled.
648 * KERN_RESOURCE_SHORTAGE on memory alloc failure or reaching max corpse.
649 */
650 kern_return_t
task_generate_corpse_internal(task_t task,task_t * corpse_task,thread_t * exc_thread,exception_type_t etype,mach_exception_data_type_t code,mach_exception_data_type_t subcode,void * reason)651 task_generate_corpse_internal(
652 task_t task,
653 task_t *corpse_task,
654 thread_t *exc_thread,
655 exception_type_t etype,
656 mach_exception_data_type_t code,
657 mach_exception_data_type_t subcode,
658 void *reason)
659 {
660 task_t new_task = TASK_NULL;
661 thread_t thread = THREAD_NULL;
662 thread_t thread_next = THREAD_NULL;
663 kern_return_t kr;
664 struct proc *p = NULL;
665 int is_64bit_addr;
666 int is_64bit_data;
667 uint32_t t_flags;
668 uint32_t t_flags_ro;
669 uint64_t *udata_buffer = NULL;
670 int size = 0;
671 int num_udata = 0;
672 corpse_flags_t kc_u_flags = CORPSE_CRASHINFO_HAS_REF;
673 void *corpse_proc = NULL;
674
675 #if CONFIG_MACF
676 struct label *label = NULL;
677 #endif
678
679 if (!corpses_enabled()) {
680 return KERN_NOT_SUPPORTED;
681 }
682
683 if (task_corpse_forking_disabled(task)) {
684 os_log(OS_LOG_DEFAULT, "corpse for pid %d disabled via SPI\n", task_pid(task));
685 return KERN_FAILURE;
686 }
687
688 if (etype == EXC_GUARD && EXC_GUARD_DECODE_GUARD_TYPE(code) == GUARD_TYPE_USER) {
689 kc_u_flags |= CORPSE_CRASHINFO_USER_FAULT;
690 }
691
692 kr = task_crashinfo_get_ref(kc_u_flags);
693 if (kr != KERN_SUCCESS) {
694 return kr;
695 }
696
697 /* Having a task reference does not guarantee a proc reference */
698 p = proc_find(task_pid(task));
699 if (p == NULL) {
700 kr = KERN_INVALID_TASK;
701 goto error_task_generate_corpse;
702 }
703
704 is_64bit_addr = IS_64BIT_PROCESS(p);
705 is_64bit_data = (task == TASK_NULL) ? is_64bit_addr : task_get_64bit_data(task);
706 t_flags = TF_CORPSE_FORK |
707 TF_PENDING_CORPSE |
708 (is_64bit_addr ? TF_64B_ADDR : TF_NONE) |
709 (is_64bit_data ? TF_64B_DATA : TF_NONE);
710 t_flags_ro = TFRO_CORPSE;
711
712 #if CONFIG_MACF
713 /* Create the corpse label credentials from the process. */
714 label = mac_exc_create_label_for_proc(p);
715 #endif
716
717 corpse_proc = zalloc_flags(proc_task_zone, Z_WAITOK | Z_ZERO);
718 new_task = proc_get_task_raw(corpse_proc);
719
720 /* Create a task for corpse */
721 kr = task_create_internal(task,
722 NULL,
723 NULL,
724 TRUE,
725 is_64bit_addr,
726 is_64bit_data,
727 t_flags,
728 t_flags_ro,
729 TPF_NONE,
730 TWF_NONE,
731 new_task);
732 if (kr != KERN_SUCCESS) {
733 goto error_task_generate_corpse;
734 }
735
736 /* Enable IPC access to the corpse task */
737 ipc_task_enable(new_task);
738
739 /* new task is now referenced, do not free the struct in error case */
740 corpse_proc = NULL;
741
742 /* Create and copy threads from task, returns a ref to thread */
743 kr = task_duplicate_map_and_threads(task, p, new_task, &thread,
744 &udata_buffer, &size, &num_udata, (etype != 0));
745 if (kr != KERN_SUCCESS) {
746 goto error_task_generate_corpse;
747 }
748
749 kr = task_collect_crash_info(new_task,
750 #if CONFIG_MACF
751 label,
752 #endif
753 TRUE);
754 if (kr != KERN_SUCCESS) {
755 goto error_task_generate_corpse;
756 }
757
758 /* transfer our references to the corpse info */
759 assert(new_task->corpse_info->kcd_user_flags == 0);
760 new_task->corpse_info->kcd_user_flags = kc_u_flags;
761 kc_u_flags = 0;
762
763 kr = task_start_halt(new_task);
764 if (kr != KERN_SUCCESS) {
765 goto error_task_generate_corpse;
766 }
767
768 /* terminate the ipc space */
769 ipc_space_terminate(new_task->itk_space);
770
771 /* Populate the corpse blob, use the proc struct of task instead of corpse task */
772 gather_populate_corpse_crashinfo(p, new_task,
773 code, subcode, udata_buffer, num_udata, reason, etype);
774
775 /* Add it to global corpse task list */
776 task_add_to_corpse_task_list(new_task);
777
778 *corpse_task = new_task;
779 *exc_thread = thread;
780
781 error_task_generate_corpse:
782 #if CONFIG_MACF
783 if (label) {
784 mac_exc_free_label(label);
785 }
786 #endif
787
788 /* Release the proc reference */
789 if (p != NULL) {
790 proc_rele(p);
791 }
792
793 if (corpse_proc != NULL) {
794 zfree(proc_task_zone, corpse_proc);
795 }
796
797 if (kr != KERN_SUCCESS) {
798 if (thread != THREAD_NULL) {
799 thread_deallocate(thread);
800 }
801 if (new_task != TASK_NULL) {
802 task_lock(new_task);
803 /* Terminate all the other threads in the task. */
804 queue_iterate(&new_task->threads, thread_next, thread_t, task_threads)
805 {
806 thread_terminate_internal(thread_next);
807 }
808 /* wait for all the threads in the task to terminate */
809 task_wait_till_threads_terminate_locked(new_task);
810 task_unlock(new_task);
811
812 task_clear_corpse(new_task);
813 task_terminate_internal(new_task);
814 task_deallocate(new_task);
815 }
816 if (kc_u_flags) {
817 task_crashinfo_release_ref(kc_u_flags);
818 }
819 }
820 /* Free the udata buffer allocated in task_duplicate_map_and_threads */
821 kfree_data(udata_buffer, size);
822
823 return kr;
824 }
825
826 static kern_return_t
task_map_kcdata_64(task_t task,void * kcdata_addr,mach_vm_address_t * uaddr,mach_vm_size_t kcd_size,vm_tag_t tag)827 task_map_kcdata_64(
828 task_t task,
829 void *kcdata_addr,
830 mach_vm_address_t *uaddr,
831 mach_vm_size_t kcd_size,
832 vm_tag_t tag)
833 {
834 kern_return_t kr;
835 mach_vm_offset_t udata_ptr;
836
837 kr = mach_vm_allocate_kernel(task->map, &udata_ptr, (size_t)kcd_size,
838 VM_FLAGS_ANYWHERE, tag);
839 if (kr != KERN_SUCCESS) {
840 return kr;
841 }
842 copyout(kcdata_addr, (user_addr_t)udata_ptr, (size_t)kcd_size);
843 *uaddr = udata_ptr;
844
845 return KERN_SUCCESS;
846 }
847
848 /*
849 * Routine: task_map_corpse_info
850 * params: task - Map the corpse info in task's address space
851 * corpse_task - task port of the corpse
852 * kcd_addr_begin - address of the mapped corpse info
853 * kcd_addr_begin - size of the mapped corpse info
854 * returns: KERN_SUCCESS on Success.
855 * KERN_FAILURE on Failure.
856 * KERN_INVALID_ARGUMENT on invalid arguments.
857 * Note: Temporary function, will be deleted soon.
858 */
859 kern_return_t
task_map_corpse_info(task_t task,task_t corpse_task,vm_address_t * kcd_addr_begin,uint32_t * kcd_size)860 task_map_corpse_info(
861 task_t task,
862 task_t corpse_task,
863 vm_address_t *kcd_addr_begin,
864 uint32_t *kcd_size)
865 {
866 kern_return_t kr;
867 mach_vm_address_t kcd_addr_begin_64;
868 mach_vm_size_t size_64;
869
870 kr = task_map_corpse_info_64(task, corpse_task, &kcd_addr_begin_64, &size_64);
871 if (kr != KERN_SUCCESS) {
872 return kr;
873 }
874
875 *kcd_addr_begin = (vm_address_t)kcd_addr_begin_64;
876 *kcd_size = (uint32_t) size_64;
877 return KERN_SUCCESS;
878 }
879
880 /*
881 * Routine: task_map_corpse_info_64
882 * params: task - Map the corpse info in task's address space
883 * corpse_task - task port of the corpse
884 * kcd_addr_begin - address of the mapped corpse info (takes mach_vm_addess_t *)
885 * kcd_size - size of the mapped corpse info (takes mach_vm_size_t *)
886 * returns: KERN_SUCCESS on Success.
887 * KERN_FAILURE on Failure.
888 * KERN_INVALID_ARGUMENT on invalid arguments.
889 */
890 kern_return_t
task_map_corpse_info_64(task_t task,task_t corpse_task,mach_vm_address_t * kcd_addr_begin,mach_vm_size_t * kcd_size)891 task_map_corpse_info_64(
892 task_t task,
893 task_t corpse_task,
894 mach_vm_address_t *kcd_addr_begin,
895 mach_vm_size_t *kcd_size)
896 {
897 kern_return_t kr;
898 mach_vm_offset_t crash_data_ptr = 0;
899 const mach_vm_size_t size = CORPSEINFO_ALLOCATION_SIZE;
900 void *corpse_info_kernel = NULL;
901
902 if (task == TASK_NULL || task_is_a_corpse(task) ||
903 corpse_task == TASK_NULL || !task_is_a_corpse(corpse_task)) {
904 return KERN_INVALID_ARGUMENT;
905 }
906
907 corpse_info_kernel = kcdata_memory_get_begin_addr(corpse_task->corpse_info);
908 if (corpse_info_kernel == NULL) {
909 return KERN_INVALID_ARGUMENT;
910 }
911
912 kr = task_map_kcdata_64(task, corpse_info_kernel, &crash_data_ptr, size,
913 VM_MEMORY_CORPSEINFO);
914
915 if (kr == KERN_SUCCESS) {
916 *kcd_addr_begin = crash_data_ptr;
917 *kcd_size = size;
918 }
919
920 return kr;
921 }
922
923 /*
924 * Routine: task_map_kcdata_object_64
925 * params: task - Map the underlying kcdata in task's address space
926 * kcdata_obj - Object representing the data
927 * kcd_addr_begin - Address of the mapped kcdata
928 * kcd_size - Size of the mapped kcdata
929 * returns: KERN_SUCCESS on Success.
930 * KERN_FAILURE on Failure.
931 * KERN_INVALID_ARGUMENT on invalid arguments.
932 */
933 kern_return_t
task_map_kcdata_object_64(task_t task,kcdata_object_t kcdata_obj,mach_vm_address_t * kcd_addr_begin,mach_vm_size_t * kcd_size)934 task_map_kcdata_object_64(
935 task_t task,
936 kcdata_object_t kcdata_obj,
937 mach_vm_address_t *kcd_addr_begin,
938 mach_vm_size_t *kcd_size)
939 {
940 kern_return_t kr;
941 mach_vm_offset_t bt_data_ptr = 0;
942 const mach_vm_size_t size = BTINFO_ALLOCATION_SIZE;
943 void *bt_info_kernel = NULL;
944
945 if (task == TASK_NULL || task_is_a_corpse(task) ||
946 kcdata_obj == KCDATA_OBJECT_NULL) {
947 return KERN_INVALID_ARGUMENT;
948 }
949
950 bt_info_kernel = kcdata_memory_get_begin_addr(kcdata_obj->ko_data);
951 if (bt_info_kernel == NULL) {
952 return KERN_INVALID_ARGUMENT;
953 }
954
955 kr = task_map_kcdata_64(task, bt_info_kernel, &bt_data_ptr, size,
956 VM_MEMORY_BTINFO);
957
958 if (kr == KERN_SUCCESS) {
959 *kcd_addr_begin = bt_data_ptr;
960 *kcd_size = size;
961 }
962
963 return kr;
964 }
965
966 uint64_t
task_corpse_get_crashed_thread_id(task_t corpse_task)967 task_corpse_get_crashed_thread_id(task_t corpse_task)
968 {
969 return corpse_task->crashed_thread_id;
970 }
971