1 /*
2 * Copyright (c) 2000-2020 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 /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
29 /*
30 * Copyright (c) 1982, 1986, 1989, 1991, 1993
31 * The Regents of the University of California. All rights reserved.
32 * (c) UNIX System Laboratories, Inc.
33 * All or some portions of this file are derived from material licensed
34 * to the University of California by American Telephone and Telegraph
35 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
36 * the permission of UNIX System Laboratories, Inc.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. All advertising materials mentioning features or use of this software
47 * must display the following acknowledgement:
48 * This product includes software developed by the University of
49 * California, Berkeley and its contributors.
50 * 4. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 * @(#)kern_fork.c 8.8 (Berkeley) 2/14/95
67 */
68 /*
69 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
70 * support for mandatory and extensible security protections. This notice
71 * is included in support of clause 2.2 (b) of the Apple Public License,
72 * Version 2.0.
73 */
74 /*
75 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
76 * support for mandatory and extensible security protections. This notice
77 * is included in support of clause 2.2 (b) of the Apple Public License,
78 * Version 2.0.
79 */
80
81 #include <kern/assert.h>
82 #include <kern/bits.h>
83 #include <sys/param.h>
84 #include <sys/systm.h>
85 #include <sys/filedesc.h>
86 #include <sys/kernel.h>
87 #include <sys/malloc.h>
88 #include <sys/proc_internal.h>
89 #include <sys/kauth.h>
90 #include <sys/user.h>
91 #include <sys/reason.h>
92 #include <sys/resourcevar.h>
93 #include <sys/vnode_internal.h>
94 #include <sys/file_internal.h>
95 #include <sys/acct.h>
96 #include <sys/codesign.h>
97 #include <sys/sysent.h>
98 #include <sys/sysproto.h>
99 #include <sys/ulock.h>
100 #if CONFIG_PERSONAS
101 #include <sys/persona.h>
102 #endif
103 #include <sys/doc_tombstone.h>
104 #if CONFIG_DTRACE
105 /* Do not include dtrace.h, it redefines kmem_[alloc/free] */
106 extern void (*dtrace_proc_waitfor_exec_ptr)(proc_t);
107 extern void dtrace_proc_fork(proc_t, proc_t, int);
108
109 /*
110 * Since dtrace_proc_waitfor_exec_ptr can be added/removed in dtrace_subr.c,
111 * we will store its value before actually calling it.
112 */
113 static void (*dtrace_proc_waitfor_hook)(proc_t) = NULL;
114
115 #include <sys/dtrace_ptss.h>
116 #endif
117
118 #include <security/audit/audit.h>
119
120 #include <mach/mach_types.h>
121 #include <kern/coalition.h>
122 #include <kern/ipc_kobject.h>
123 #include <kern/kern_types.h>
124 #include <kern/kalloc.h>
125 #include <kern/mach_param.h>
126 #include <kern/task.h>
127 #include <kern/thread.h>
128 #include <kern/thread_call.h>
129 #include <kern/zalloc.h>
130
131 #if CONFIG_MACF
132 #include <security/mac_framework.h>
133 #include <security/mac_mach_internal.h>
134 #endif
135
136 #include <vm/vm_map.h>
137 #include <vm/vm_protos.h>
138 #include <vm/vm_shared_region.h>
139 #include <vm/vm_pageout_xnu.h>
140
141 #include <sys/shm_internal.h> /* for shmfork() */
142 #include <mach/task.h> /* for thread_create() */
143 #include <mach/thread_act.h> /* for thread_resume() */
144
145 #include <sys/sdt.h>
146
147 #if CONFIG_MEMORYSTATUS
148 #include <sys/kern_memorystatus.h>
149 #endif
150
151 static const uint64_t startup_serial_num_procs = 300;
152 bool startup_serial_logging_active = true;
153
154 /* XXX routines which should have Mach prototypes, but don't */
155 extern void act_thread_catt(void *ctx);
156 void thread_set_child(thread_t child, int pid);
157 boolean_t thread_is_active(thread_t thread);
158 void *act_thread_csave(void);
159 extern boolean_t task_is_exec_copy(task_t);
160 int nextpidversion = 0;
161
162 void ipc_task_enable(task_t task);
163
164 proc_t forkproc(proc_t, cloneproc_flags_t);
165 void forkproc_free(proc_t);
166 thread_t fork_create_child(task_t parent_task,
167 coalition_t *parent_coalitions,
168 proc_t child,
169 int is_64bit_addr,
170 int is_64bit_data,
171 cloneproc_flags_t clone_flags);
172
173 __private_extern__ const size_t uthread_size = sizeof(struct uthread);
174 static LCK_GRP_DECLARE(rethrottle_lock_grp, "rethrottle");
175
176 os_refgrp_decl(, p_refgrp, "proc", NULL);
177
178 extern const size_t task_alignment;
179 const size_t proc_alignment = _Alignof(struct proc);
180
181 extern size_t task_struct_size;
182 size_t proc_struct_size = sizeof(struct proc);
183 size_t proc_and_task_size;
184
185 ZONE_DECLARE_ID(ZONE_ID_PROC_TASK, struct proc);
186 SECURITY_READ_ONLY_LATE(zone_t) proc_task_zone;
187
188 KALLOC_TYPE_DEFINE(proc_stats_zone, struct pstats, KT_DEFAULT);
189
190 /*
191 * fork1
192 *
193 * Description: common code used by all new process creation other than the
194 * bootstrap of the initial process on the system
195 *
196 * Parameters: parent_proc parent process of the process being
197 * child_threadp pointer to location to receive the
198 * Mach thread_t of the child process
199 * created
200 * kind kind of creation being requested
201 * coalitions if spawn, the set of coalitions the
202 * child process should join, or NULL to
203 * inherit the parent's. On non-spawns,
204 * this param is ignored and the child
205 * always inherits the parent's
206 * coalitions.
207 *
208 * Notes: Permissable values for 'kind':
209 *
210 * PROC_CREATE_FORK Create a complete process which will
211 * return actively running in both the
212 * parent and the child; the child copies
213 * the parent address space.
214 * PROC_CREATE_SPAWN Create a complete process which will
215 * return actively running in the parent
216 * only after returning actively running
217 * in the child; the child address space
218 * is newly created by an image activator,
219 * after which the child is run.
220 *
221 * At first it may seem strange that we return the child thread
222 * address rather than process structure, since the process is
223 * the only part guaranteed to be "new"; however, since we do
224 * not actualy adjust other references between Mach and BSD, this
225 * is the only method which guarantees us the ability to get
226 * back to the other information.
227 */
228 int
fork1(proc_t parent_proc,thread_t * child_threadp,int kind,coalition_t * coalitions)229 fork1(proc_t parent_proc, thread_t *child_threadp, int kind, coalition_t *coalitions)
230 {
231 proc_t child_proc = NULL; /* set in switch, but compiler... */
232 thread_t child_thread = NULL;
233 uid_t uid;
234 size_t count;
235 int err = 0;
236 int spawn = 0;
237 rlim_t rlimit_nproc_cur;
238
239 /*
240 * Although process entries are dynamically created, we still keep
241 * a global limit on the maximum number we will create. Don't allow
242 * a nonprivileged user to use the last process; don't let root
243 * exceed the limit. The variable nprocs is the current number of
244 * processes, maxproc is the limit.
245 */
246 uid = kauth_getruid();
247 proc_list_lock();
248 if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
249 #if (DEVELOPMENT || DEBUG) && !defined(XNU_TARGET_OS_OSX)
250 /*
251 * On the development kernel, panic so that the fact that we hit
252 * the process limit is obvious, as this may very well wedge the
253 * system.
254 */
255 panic("The process table is full; parent pid=%d", proc_getpid(parent_proc));
256 #endif
257 proc_list_unlock();
258 tablefull("proc");
259 return EAGAIN;
260 }
261 proc_list_unlock();
262
263 /*
264 * Increment the count of procs running with this uid. Don't allow
265 * a nonprivileged user to exceed their current limit, which is
266 * always less than what an rlim_t can hold.
267 * (locking protection is provided by list lock held in chgproccnt)
268 */
269 count = chgproccnt(uid, 1);
270 rlimit_nproc_cur = proc_limitgetcur(parent_proc, RLIMIT_NPROC);
271 if (uid != 0 &&
272 (rlim_t)count > rlimit_nproc_cur) {
273 #if (DEVELOPMENT || DEBUG) && !defined(XNU_TARGET_OS_OSX)
274 /*
275 * On the development kernel, panic so that the fact that we hit
276 * the per user process limit is obvious. This may be less dire
277 * than hitting the global process limit, but we cannot rely on
278 * that.
279 */
280 panic("The per-user process limit has been hit; parent pid=%d, uid=%d", proc_getpid(parent_proc), uid);
281 #endif
282 err = EAGAIN;
283 goto bad;
284 }
285
286 #if CONFIG_MACF
287 /*
288 * Determine if MAC policies applied to the process will allow
289 * it to fork. This is an advisory-only check.
290 */
291 err = mac_proc_check_fork(parent_proc);
292 if (err != 0) {
293 goto bad;
294 }
295 #endif
296
297 switch (kind) {
298 case PROC_CREATE_SPAWN:
299 /*
300 * A spawned process differs from a forked process in that
301 * the spawned process does not carry around the parents
302 * baggage with regard to address space copying, dtrace,
303 * and so on.
304 */
305 spawn = 1;
306
307 OS_FALLTHROUGH;
308
309 case PROC_CREATE_FORK:
310 /*
311 * When we clone the parent process, we are going to inherit
312 * its task attributes and memory, since when we fork, we
313 * will, in effect, create a duplicate of it, with only minor
314 * differences. Contrarily, spawned processes do not inherit.
315 */
316 if ((child_thread = cloneproc(proc_task(parent_proc),
317 spawn ? coalitions : NULL,
318 parent_proc,
319 spawn ? CLONEPROC_SPAWN : CLONEPROC_FORK)) == NULL) {
320 /* Failed to create thread */
321 err = EAGAIN;
322 goto bad;
323 }
324
325 /* child_proc = child_thread->task->proc; */
326 child_proc = (proc_t)(get_bsdtask_info(get_threadtask(child_thread)));
327
328 if (!spawn) {
329 /* Copy current thread state into the child thread (only for fork) */
330 thread_dup(child_thread);
331 }
332
333 // XXX BEGIN: wants to move to be common code (and safe)
334 #if CONFIG_MACF
335 /*
336 * allow policies to associate the credential/label that
337 * we referenced from the parent ... with the child
338 * JMM - this really isn't safe, as we can drop that
339 * association without informing the policy in other
340 * situations (keep long enough to get policies changed)
341 */
342 mac_cred_label_associate_fork(proc_ucred_unsafe(child_proc),
343 child_proc);
344 #endif
345
346 /*
347 * Propogate change of PID - may get new cred if auditing.
348 */
349 set_security_token(child_proc, proc_ucred_unsafe(child_proc));
350
351 AUDIT_ARG(pid, proc_getpid(child_proc));
352
353 // XXX END: wants to move to be common code (and safe)
354
355 /*
356 * Blow thread state information; this is what gives the child
357 * process its "return" value from a fork() call.
358 *
359 * Note: this should probably move to fork() proper, since it
360 * is not relevent to spawn, and the value won't matter
361 * until we resume the child there. If you are in here
362 * refactoring code, consider doing this at the same time.
363 */
364 thread_set_child(child_thread, proc_getpid(child_proc));
365
366 child_proc->p_acflag = AFORK; /* forked but not exec'ed */
367
368 #if CONFIG_DTRACE
369 dtrace_proc_fork(parent_proc, child_proc, spawn);
370 #endif /* CONFIG_DTRACE */
371 if (!spawn) {
372 /*
373 * Of note, we need to initialize the bank context behind
374 * the protection of the proc_trans lock to prevent a race with exit.
375 */
376 task_bank_init(get_threadtask(child_thread));
377 }
378
379 break;
380
381 default:
382 panic("fork1 called with unknown kind %d", kind);
383 break;
384 }
385
386
387 /* return the thread pointer to the caller */
388 *child_threadp = child_thread;
389
390 bad:
391 /*
392 * In the error case, we return a 0 value for the returned pid (but
393 * it is ignored in the trampoline due to the error return); this
394 * is probably not necessary.
395 */
396 if (err) {
397 (void)chgproccnt(uid, -1);
398 }
399
400 return err;
401 }
402
403
404
405
406 /*
407 * fork_create_child
408 *
409 * Description: Common operations associated with the creation of a child
410 * process. Return with new task and first thread's control port movable
411 * and not pinned.
412 *
413 * Parameters: parent_task parent task
414 * parent_coalitions parent's set of coalitions
415 * child_proc child process
416 * inherit_memory TRUE, if the parents address space is
417 * to be inherited by the child
418 * is_64bit_addr TRUE, if the child being created will
419 * be associated with a 64 bit address space
420 * is_64bit_data TRUE if the child being created will use a
421 * 64-bit register state
422 * in_exec TRUE, if called from execve or posix spawn set exec
423 * FALSE, if called from fork or vfexec
424 *
425 * Note: This code is called in the fork() case, from the execve() call
426 * graph, from the posix_spawn() call graph (which implicitly
427 * includes a vfork() equivalent call, and in the system
428 * bootstrap case.
429 *
430 * It creates a new task and thread (and as a side effect of the
431 * thread creation, a uthread) in the parent coalition set, which is
432 * then associated with the process 'child'. If the parent
433 * process address space is to be inherited, then a flag
434 * indicates that the newly created task should inherit this from
435 * the child task.
436 *
437 * As a special concession to bootstrapping the initial process
438 * in the system, it's possible for 'parent_task' to be TASK_NULL;
439 * in this case, 'inherit_memory' MUST be FALSE.
440 */
441 thread_t
fork_create_child(task_t parent_task,coalition_t * parent_coalitions,proc_t child_proc,int is_64bit_addr,int is_64bit_data,cloneproc_flags_t clone_flags)442 fork_create_child(task_t parent_task,
443 coalition_t *parent_coalitions,
444 proc_t child_proc,
445 int is_64bit_addr,
446 int is_64bit_data,
447 cloneproc_flags_t clone_flags)
448 {
449 thread_t child_thread = NULL;
450 task_t child_task;
451 kern_return_t result;
452 proc_ro_t proc_ro;
453 bool inherit_memory = !!(clone_flags & CLONEPROC_FORK);
454 bool in_exec = !!(clone_flags & CLONEPROC_EXEC);
455 /*
456 * Exec complete hook should be called for spawn and exec, but not for fork.
457 */
458 uint8_t returnwaitflags = (!inherit_memory ? TRW_LEXEC_COMPLETE : 0) |
459 (TRW_LRETURNWAIT | TRW_LRETURNWAITER);
460
461 proc_ro = proc_get_ro(child_proc);
462 if (proc_ro_task(proc_ro) != NULL) {
463 panic("Proc_ro_task for newly created proc %p is not NULL", child_proc);
464 }
465
466 child_task = proc_get_task_raw(child_proc);
467
468 /*
469 * Create a new task for the child process, IPC access to the new task will
470 * be set up after task has been fully initialized.
471 */
472 result = task_create_internal(parent_task,
473 proc_ro,
474 parent_coalitions,
475 inherit_memory,
476 is_64bit_addr,
477 is_64bit_data,
478 TF_NONE,
479 TF_NONE,
480 in_exec ? TPF_EXEC_COPY : TPF_NONE, /* Mark the task exec copy if in execve */
481 returnwaitflags, /* All created threads will wait in task_wait_to_return */
482 child_task);
483 if (result != KERN_SUCCESS) {
484 printf("%s: task_create_internal failed. Code: %d\n",
485 __func__, result);
486 goto bad;
487 }
488
489 /* Set the child proc process to child task */
490 proc_set_task(child_proc, child_task);
491
492 /* Set child task process to child proc */
493 set_bsdtask_info(child_task, child_proc);
494
495 /* Propagate CPU limit timer from parent */
496 if (timerisset(&child_proc->p_rlim_cpu)) {
497 task_vtimer_set(child_task, TASK_VTIMER_RLIM);
498 }
499
500 /*
501 * Set child process BSD visible scheduler priority if nice value
502 * inherited from parent
503 */
504 if (child_proc->p_nice != 0) {
505 resetpriority(child_proc);
506 }
507
508 /*
509 * Create main thread for the child process. Its control port is not immovable/pinned
510 * until main_thread_set_immovable_pinned().
511 *
512 * The new thread is waiting on the event triggered by 'task_clear_return_wait'
513 */
514 result = main_thread_create_waiting(child_task,
515 (thread_continue_t)task_wait_to_return,
516 task_get_return_wait_event(child_task),
517 &child_thread);
518
519 if (result != KERN_SUCCESS) {
520 printf("%s: thread_create failed. Code: %d\n",
521 __func__, result);
522 task_deallocate(child_task);
523 child_task = NULL;
524 }
525
526 /*
527 * Tag thread as being the first thread in its task.
528 */
529 thread_set_tag(child_thread, THREAD_TAG_MAINTHREAD);
530
531 bad:
532 thread_yield_internal(1);
533
534 return child_thread;
535 }
536
537
538 /*
539 * fork
540 *
541 * Description: fork system call.
542 *
543 * Parameters: parent Parent process to fork
544 * uap (void) [unused]
545 * retval Return value
546 *
547 * Returns: 0 Success
548 * EAGAIN Resource unavailable, try again
549 *
550 * Notes: Attempts to create a new child process which inherits state
551 * from the parent process. If successful, the call returns
552 * having created an initially suspended child process with an
553 * extra Mach task and thread reference, for which the thread
554 * is initially suspended. Until we resume the child process,
555 * it is not yet running.
556 *
557 * The return information to the child is contained in the
558 * thread state structure of the new child, and does not
559 * become visible to the child through a normal return process,
560 * since it never made the call into the kernel itself in the
561 * first place.
562 *
563 * After resuming the thread, this function returns directly to
564 * the parent process which invoked the fork() system call.
565 *
566 * Important: The child thread_resume occurs before the parent returns;
567 * depending on scheduling latency, this means that it is not
568 * deterministic as to whether the parent or child is scheduled
569 * to run first. It is entirely possible that the child could
570 * run to completion prior to the parent running.
571 */
572 int
fork(proc_t parent_proc,__unused struct fork_args * uap,int32_t * retval)573 fork(proc_t parent_proc, __unused struct fork_args *uap, int32_t *retval)
574 {
575 thread_t child_thread;
576 int err;
577
578 retval[1] = 0; /* flag parent return for user space */
579
580 if ((err = fork1(parent_proc, &child_thread, PROC_CREATE_FORK, NULL)) == 0) {
581 task_t child_task;
582 proc_t child_proc;
583
584 /* Return to the parent */
585 child_proc = (proc_t)get_bsdthreadtask_info(child_thread);
586 retval[0] = proc_getpid(child_proc);
587
588 child_task = (task_t)get_threadtask(child_thread);
589 assert(child_task != TASK_NULL);
590
591 /* task_control_port_options has been inherited from parent, apply it */
592 task_set_immovable_pinned(child_task);
593 main_thread_set_immovable_pinned(child_thread);
594
595 /*
596 * Since the task ports for this new task are now set to be immovable,
597 * we can enable them.
598 */
599 ipc_task_enable(get_threadtask(child_thread));
600
601 /*
602 * Drop the signal lock on the child which was taken on our
603 * behalf by forkproc()/cloneproc() to prevent signals being
604 * received by the child in a partially constructed state.
605 */
606 proc_signalend(child_proc, 0);
607 proc_transend(child_proc, 0);
608
609 /* flag the fork has occurred */
610 proc_knote(parent_proc, NOTE_FORK | proc_getpid(child_proc));
611 DTRACE_PROC1(create, proc_t, child_proc);
612
613 #if CONFIG_DTRACE
614 if ((dtrace_proc_waitfor_hook = dtrace_proc_waitfor_exec_ptr) != NULL) {
615 (*dtrace_proc_waitfor_hook)(child_proc);
616 }
617 #endif
618
619 /*
620 * If current process died during the fork, the child would contain
621 * non consistent vmmap, kill the child and reap it internally.
622 */
623 if (parent_proc->p_lflag & P_LEXIT || !thread_is_active(current_thread())) {
624 task_terminate_internal(child_task);
625 proc_list_lock();
626 child_proc->p_listflag |= P_LIST_DEADPARENT;
627 proc_list_unlock();
628 }
629
630 /* "Return" to the child */
631 task_clear_return_wait(get_threadtask(child_thread), TCRW_CLEAR_ALL_WAIT);
632
633 /* drop the extra references we got during the creation */
634 task_deallocate(child_task);
635 thread_deallocate(child_thread);
636 }
637
638 return err;
639 }
640
641
642 /*
643 * cloneproc
644 *
645 * Description: Create a new process from a specified process.
646 *
647 * Parameters: parent_task The parent task to be cloned, or
648 * TASK_NULL is task characteristics
649 * are not to be inherited
650 * be cloned, or TASK_NULL if the new
651 * task is not to inherit the VM
652 * characteristics of the parent
653 * parent_proc The parent process to be cloned
654 * clone_flags Clone flags to specify if the cloned
655 * process should inherit memory,
656 * marked as memory stat internal,
657 * or if the cloneproc is called for exec.
658 *
659 * Returns: !NULL pointer to new child thread
660 * NULL Failure (unspecified)
661 *
662 * Note: On return newly created child process has signal lock held
663 * to block delivery of signal to it if called with lock set.
664 * fork() code needs to explicity remove this lock before
665 * signals can be delivered
666 *
667 * In the case of bootstrap, this function can be called from
668 * bsd_utaskbootstrap() in order to bootstrap the first process;
669 * the net effect is to provide a uthread structure for the
670 * kernel process associated with the kernel task.
671 *
672 * XXX: Tristating using the value parent_task as the major key
673 * and inherit_memory as the minor key is something we should
674 * refactor later; we owe the current semantics, ultimately,
675 * to the semantics of task_create_internal. For now, we will
676 * live with this being somewhat awkward.
677 */
678 thread_t
cloneproc(task_t parent_task,coalition_t * parent_coalitions,proc_t parent_proc,cloneproc_flags_t clone_flags)679 cloneproc(task_t parent_task, coalition_t *parent_coalitions, proc_t parent_proc, cloneproc_flags_t clone_flags)
680 {
681 #if !CONFIG_MEMORYSTATUS
682 #pragma unused(cloning_initproc)
683 #endif
684 task_t child_task;
685 proc_t child_proc;
686 thread_t child_thread = NULL;
687 bool cloning_initproc = !!(clone_flags & CLONEPROC_INITPROC);
688 bool in_exec = !!(clone_flags & CLONEPROC_EXEC);
689
690 if ((child_proc = forkproc(parent_proc, clone_flags)) == NULL) {
691 /* Failed to allocate new process */
692 goto bad;
693 }
694
695 /*
696 * In the case where the parent_task is TASK_NULL (during the init path)
697 * we make the assumption that the register size will be the same as the
698 * address space size since there's no way to determine the possible
699 * register size until an image is exec'd.
700 *
701 * The only architecture that has different address space and register sizes
702 * (arm64_32) isn't being used within kernel-space, so the above assumption
703 * always holds true for the init path.
704 */
705 const int parent_64bit_addr = parent_proc->p_flag & P_LP64;
706 const int parent_64bit_data = (parent_task == TASK_NULL) ? parent_64bit_addr : task_get_64bit_data(parent_task);
707
708 child_thread = fork_create_child(parent_task,
709 parent_coalitions,
710 child_proc,
711 parent_64bit_addr,
712 parent_64bit_data,
713 clone_flags);
714
715 if (child_thread == NULL) {
716 /*
717 * Failed to create thread; now we must deconstruct the new
718 * process previously obtained from forkproc().
719 */
720 forkproc_free(child_proc);
721 goto bad;
722 }
723
724 child_task = get_threadtask(child_thread);
725 if (parent_64bit_addr) {
726 OSBitOrAtomic(P_LP64, (UInt32 *)&child_proc->p_flag);
727 get_bsdthread_info(child_thread)->uu_flag |= UT_LP64;
728 } else {
729 OSBitAndAtomic(~((uint32_t)P_LP64), (UInt32 *)&child_proc->p_flag);
730 get_bsdthread_info(child_thread)->uu_flag &= ~UT_LP64;
731 }
732
733 #if CONFIG_MEMORYSTATUS
734 if (cloning_initproc ||
735 (in_exec && (parent_proc->p_memstat_state & P_MEMSTAT_INTERNAL))) {
736 proc_list_lock();
737 child_proc->p_memstat_state |= P_MEMSTAT_INTERNAL;
738 child_proc->p_memstat_effectivepriority = JETSAM_PRIORITY_INTERNAL;
739 child_proc->p_memstat_requestedpriority = JETSAM_PRIORITY_INTERNAL;
740 proc_list_unlock();
741 }
742 if (in_exec && parent_proc->p_memstat_relaunch_flags != P_MEMSTAT_RELAUNCH_UNKNOWN) {
743 memorystatus_relaunch_flags_update(child_proc, parent_proc->p_memstat_relaunch_flags);
744 }
745 #endif
746
747 /* make child visible */
748 pinsertchild(parent_proc, child_proc, in_exec);
749
750 /*
751 * Make child runnable, set start time.
752 */
753 child_proc->p_stat = SRUN;
754 bad:
755 return child_thread;
756 }
757
758 void
proc_set_sigact(proc_t p,int sig,user_addr_t sigact)759 proc_set_sigact(proc_t p, int sig, user_addr_t sigact)
760 {
761 assert((sig > 0) && (sig < NSIG));
762
763 p->p_sigacts.ps_sigact[sig] = sigact;
764 }
765
766 void
proc_set_trampact(proc_t p,int sig,user_addr_t trampact)767 proc_set_trampact(proc_t p, int sig, user_addr_t trampact)
768 {
769 assert((sig > 0) && (sig < NSIG));
770
771 p->p_sigacts.ps_trampact[sig] = trampact;
772 }
773
774 void
proc_set_sigact_trampact(proc_t p,int sig,user_addr_t sigact,user_addr_t trampact)775 proc_set_sigact_trampact(proc_t p, int sig, user_addr_t sigact, user_addr_t trampact)
776 {
777 assert((sig > 0) && (sig < NSIG));
778
779 p->p_sigacts.ps_sigact[sig] = sigact;
780 p->p_sigacts.ps_trampact[sig] = trampact;
781 }
782
783 void
proc_reset_sigact(proc_t p,sigset_t sigs)784 proc_reset_sigact(proc_t p, sigset_t sigs)
785 {
786 user_addr_t *sigacts = p->p_sigacts.ps_sigact;
787 int nc;
788
789 while (sigs) {
790 nc = ffs((unsigned int)sigs);
791 if (sigacts[nc] != SIG_DFL) {
792 sigacts[nc] = SIG_DFL;
793 }
794 sigs &= ~sigmask(nc);
795 }
796 }
797
798 /*
799 * Destroy a process structure that resulted from a call to forkproc(), but
800 * which must be returned to the system because of a subsequent failure
801 * preventing it from becoming active.
802 *
803 * Parameters: p The incomplete process from forkproc()
804 *
805 * Returns: (void)
806 *
807 * Note: This function should only be used in an error handler following
808 * a call to forkproc().
809 *
810 * Operations occur in reverse order of those in forkproc().
811 */
812 void
forkproc_free(proc_t p)813 forkproc_free(proc_t p)
814 {
815 struct pgrp *pg;
816
817 #if CONFIG_PERSONAS
818 persona_proc_drop(p);
819 #endif /* CONFIG_PERSONAS */
820
821 #if PSYNCH
822 pth_proc_hashdelete(p);
823 #endif /* PSYNCH */
824
825 /* We held signal and a transition locks; drop them */
826 proc_signalend(p, 0);
827 proc_transend(p, 0);
828
829 /*
830 * If we have our own copy of the resource limits structure, we
831 * need to free it. If it's a shared copy, we need to drop our
832 * reference on it.
833 */
834 proc_limitdrop(p);
835
836 #if SYSV_SHM
837 /* Need to drop references to the shared memory segment(s), if any */
838 if (p->vm_shm) {
839 /*
840 * Use shmexec(): we have no address space, so no mappings
841 *
842 * XXX Yes, the routine is badly named.
843 */
844 shmexec(p);
845 }
846 #endif
847
848 /* Need to undo the effects of the fdt_fork(), if any */
849 fdt_invalidate(p);
850 fdt_destroy(p);
851
852 /*
853 * Drop the reference on a text vnode pointer, if any
854 * XXX This code is broken in forkproc(); see <rdar://4256419>;
855 * XXX if anyone ever uses this field, we will be extremely unhappy.
856 */
857 if (p->p_textvp) {
858 vnode_rele(p->p_textvp);
859 p->p_textvp = NULL;
860 }
861
862 /* Update the audit session proc count */
863 AUDIT_SESSION_PROCEXIT(p);
864
865 lck_mtx_destroy(&p->p_mlock, &proc_mlock_grp);
866 lck_mtx_destroy(&p->p_ucred_mlock, &proc_ucred_mlock_grp);
867 #if CONFIG_AUDIT
868 lck_mtx_destroy(&p->p_audit_mlock, &proc_ucred_mlock_grp);
869 #endif /* CONFIG_AUDIT */
870 #if CONFIG_DTRACE
871 lck_mtx_destroy(&p->p_dtrace_sprlock, &proc_lck_grp);
872 #endif
873 lck_spin_destroy(&p->p_slock, &proc_slock_grp);
874
875 proc_list_lock();
876 /* Decrement the count of processes in the system */
877 nprocs--;
878
879 /* quit the group */
880 pg = pgrp_leave_locked(p);
881
882 /* Take it out of process hash */
883 assert((os_ref_get_raw_mask(&p->p_refcount) >> P_REF_BITS) == 1);
884 assert((os_ref_get_raw_mask(&p->p_refcount) & P_REF_NEW) == P_REF_NEW);
885 os_atomic_xor(&p->p_refcount, P_REF_NEW | P_REF_DEAD, relaxed);
886
887 /* Remove from hash if not a shadow proc */
888 if (!proc_is_shadow(p)) {
889 phash_remove_locked(p);
890 }
891
892 proc_list_unlock();
893
894 pgrp_rele(pg);
895
896 thread_call_free(p->p_rcall);
897
898 /* Free allocated memory */
899 zfree(proc_stats_zone, p->p_stats);
900 p->p_stats = NULL;
901 if (p->p_subsystem_root_path) {
902 zfree(ZV_NAMEI, p->p_subsystem_root_path);
903 p->p_subsystem_root_path = NULL;
904 }
905
906 proc_checkdeadrefs(p);
907 proc_wait_release(p);
908 }
909
910
911 /*
912 * forkproc
913 *
914 * Description: Create a new process structure, given a parent process
915 * structure.
916 *
917 * Parameters: parent_proc The parent process
918 *
919 * Returns: !NULL The new process structure
920 * NULL Error (insufficient free memory)
921 *
922 * Note: When successful, the newly created process structure is
923 * partially initialized; if a caller needs to deconstruct the
924 * returned structure, they must call forkproc_free() to do so.
925 */
926 proc_t
forkproc(proc_t parent_proc,cloneproc_flags_t clone_flags)927 forkproc(proc_t parent_proc, cloneproc_flags_t clone_flags)
928 {
929 static uint64_t nextuniqueid = 0;
930 static pid_t lastpid = 0;
931
932 proc_t child_proc; /* Our new process */
933 int error = 0;
934 struct pgrp *pg;
935 uthread_t parent_uthread = current_uthread();
936 rlim_t rlimit_cpu_cur;
937 pid_t pid;
938 struct proc_ro_data proc_ro_data = {};
939 bool in_exec = !!(clone_flags & CLONEPROC_EXEC);
940 bool in_fork = !!(clone_flags & CLONEPROC_FORK);
941
942 child_proc = zalloc_flags(proc_task_zone, Z_WAITOK | Z_ZERO);
943
944 child_proc->p_stats = zalloc_flags(proc_stats_zone, Z_WAITOK | Z_ZERO);
945 child_proc->p_sigacts = parent_proc->p_sigacts;
946 os_ref_init_mask(&child_proc->p_refcount, P_REF_BITS, &p_refgrp, P_REF_NEW);
947 os_ref_init_raw(&child_proc->p_waitref, &p_refgrp);
948 proc_ref_hold_proc_task_struct(child_proc);
949
950 /* allocate a callout for use by interval timers */
951 child_proc->p_rcall = thread_call_allocate((thread_call_func_t)realitexpire, child_proc);
952
953
954 /*
955 * Find an unused PID.
956 */
957
958 fdt_init(child_proc);
959
960 proc_list_lock();
961
962 if (!in_exec) {
963 pid = lastpid;
964 do {
965 /*
966 * If the process ID prototype has wrapped around,
967 * restart somewhat above 0, as the low-numbered procs
968 * tend to include daemons that don't exit.
969 */
970 if (++pid >= PID_MAX) {
971 pid = 100;
972 }
973 if (pid == lastpid) {
974 panic("Unable to allocate a new pid");
975 }
976
977 /* if the pid stays in hash both for zombie and runniing state */
978 } while (phash_find_locked(pid) != PROC_NULL ||
979 pghash_exists_locked(pid) ||
980 session_find_locked(pid) != SESSION_NULL);
981
982 lastpid = pid;
983 nprocs++;
984
985 child_proc->p_pid = pid;
986 proc_ro_data.p_idversion = OSIncrementAtomic(&nextpidversion);
987 /* kernel process is handcrafted and not from fork, so start from 1 */
988 proc_ro_data.p_uniqueid = ++nextuniqueid;
989
990 /* Insert in the hash, and inherit our group (and session) */
991 phash_insert_locked(child_proc);
992
993 /* Check if the proc is from App Cryptex */
994 if (parent_proc->p_ladvflag & P_RSR) {
995 os_atomic_or(&child_proc->p_ladvflag, P_RSR, relaxed);
996 }
997 } else {
998 /* For exec copy of the proc, copy the pid, pidversion and uniqueid of original proc */
999 pid = parent_proc->p_pid;
1000 child_proc->p_pid = pid;
1001 proc_ro_data.p_idversion = parent_proc->p_proc_ro->p_idversion;
1002 proc_ro_data.p_uniqueid = parent_proc->p_proc_ro->p_uniqueid;
1003
1004 nprocs++;
1005 os_atomic_or(&child_proc->p_refcount, P_REF_SHADOW, relaxed);
1006 }
1007 pg = pgrp_enter_locked(parent_proc, child_proc);
1008 proc_list_unlock();
1009
1010 if (proc_ro_data.p_uniqueid == startup_serial_num_procs) {
1011 /*
1012 * Turn off startup serial logging now that we have reached
1013 * the defined number of startup processes.
1014 */
1015 startup_serial_logging_active = false;
1016 }
1017
1018 /*
1019 * We've identified the PID we are going to use;
1020 * initialize the new process structure.
1021 */
1022 child_proc->p_stat = SIDL;
1023
1024 /*
1025 * The zero'ing of the proc was at the allocation time due to need
1026 * for insertion to hash. Copy the section that is to be copied
1027 * directly from the parent.
1028 */
1029 child_proc->p_forkcopy = parent_proc->p_forkcopy;
1030
1031 proc_ro_data.syscall_filter_mask = proc_syscall_filter_mask(parent_proc);
1032 proc_ro_data.p_platform_data = proc_get_ro(parent_proc)->p_platform_data;
1033
1034 /*
1035 * Some flags are inherited from the parent.
1036 * Duplicate sub-structures as needed.
1037 * Increase reference counts on shared objects.
1038 * The p_stats substruct is set in vm_fork.
1039 */
1040 #if CONFIG_DELAY_IDLE_SLEEP
1041 child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_DISABLE_ASLR | P_DELAYIDLESLEEP | P_SUGID | P_AFFINITY));
1042 #else /* CONFIG_DELAY_IDLE_SLEEP */
1043 child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_DISABLE_ASLR | P_SUGID | P_AFFINITY));
1044 #endif /* CONFIG_DELAY_IDLE_SLEEP */
1045
1046 child_proc->p_vfs_iopolicy = (parent_proc->p_vfs_iopolicy & (P_VFS_IOPOLICY_INHERITED_MASK));
1047
1048 proc_set_responsible_pid(child_proc, parent_proc->p_responsible_pid);
1049
1050 /*
1051 * Note that if the current thread has an assumed identity, this
1052 * credential will be granted to the new process.
1053 * This is OK to do in exec, because it will be over-written during image activation
1054 * before the proc is visible.
1055 */
1056 kauth_cred_set(&proc_ro_data.p_ucred.__smr_ptr, kauth_cred_get());
1057
1058 lck_mtx_init(&child_proc->p_mlock, &proc_mlock_grp, &proc_lck_attr);
1059 lck_mtx_init(&child_proc->p_ucred_mlock, &proc_ucred_mlock_grp, &proc_lck_attr);
1060 #if CONFIG_AUDIT
1061 lck_mtx_init(&child_proc->p_audit_mlock, &proc_ucred_mlock_grp, &proc_lck_attr);
1062 #endif /* CONFIG_AUDIT */
1063 #if CONFIG_DTRACE
1064 lck_mtx_init(&child_proc->p_dtrace_sprlock, &proc_lck_grp, &proc_lck_attr);
1065 #endif
1066 lck_spin_init(&child_proc->p_slock, &proc_slock_grp, &proc_lck_attr);
1067
1068 klist_init(&child_proc->p_klist);
1069
1070 if (child_proc->p_textvp != NULLVP) {
1071 /* bump references to the text vnode */
1072 /* Need to hold iocount across the ref call */
1073 if ((error = vnode_getwithref(child_proc->p_textvp)) == 0) {
1074 error = vnode_ref(child_proc->p_textvp);
1075 vnode_put(child_proc->p_textvp);
1076 }
1077
1078 if (error != 0) {
1079 child_proc->p_textvp = NULLVP;
1080 }
1081 }
1082 uint64_t csflag_inherit_mask = ~CS_KILLED;
1083 if (!in_fork) {
1084 /* All non-fork paths should not inherit GTA flag */
1085 csflag_inherit_mask &= ~CS_GET_TASK_ALLOW;
1086 }
1087 proc_ro_data.p_csflags = ((uint32_t)proc_getcsflags(parent_proc) & csflag_inherit_mask);
1088
1089 child_proc->p_proc_ro = proc_ro_alloc(child_proc, &proc_ro_data, NULL, NULL);
1090
1091 /* update cred on proc */
1092 proc_update_creds_onproc(child_proc, proc_ucred_unsafe(child_proc));
1093
1094 /* update audit session proc count */
1095 AUDIT_SESSION_PROCNEW(child_proc);
1096
1097 /*
1098 * Copy the parents per process open file table to the child; if
1099 * there is a per-thread current working directory, set the childs
1100 * per-process current working directory to that instead of the
1101 * parents.
1102 */
1103 if (fdt_fork(&child_proc->p_fd, parent_proc, parent_uthread->uu_cdir, in_exec) != 0) {
1104 forkproc_free(child_proc);
1105 child_proc = NULL;
1106 goto bad;
1107 }
1108
1109 #if SYSV_SHM
1110 if (parent_proc->vm_shm && !in_exec) {
1111 /* XXX may fail to attach shm to child */
1112 (void)shmfork(parent_proc, child_proc);
1113 }
1114 #endif
1115
1116 /*
1117 * Child inherits the parent's plimit
1118 */
1119 proc_limitfork(parent_proc, child_proc);
1120
1121 rlimit_cpu_cur = proc_limitgetcur(child_proc, RLIMIT_CPU);
1122 if (rlimit_cpu_cur != RLIM_INFINITY) {
1123 child_proc->p_rlim_cpu.tv_sec = (rlimit_cpu_cur > __INT_MAX__) ? __INT_MAX__ : rlimit_cpu_cur;
1124 }
1125
1126 if (in_exec) {
1127 /* Keep the original start time for exec'ed proc */
1128 child_proc->p_stats->ps_start = parent_proc->p_stats->ps_start;
1129 child_proc->p_start.tv_sec = parent_proc->p_start.tv_sec;
1130 child_proc->p_start.tv_usec = parent_proc->p_start.tv_usec;
1131 } else {
1132 /* Intialize new process stats, including start time */
1133 /* <rdar://6640543> non-zeroed portion contains garbage AFAICT */
1134 microtime_with_abstime(&child_proc->p_start, &child_proc->p_stats->ps_start);
1135 }
1136
1137 if (pg->pg_session->s_ttyvp != NULL && parent_proc->p_flag & P_CONTROLT) {
1138 os_atomic_or(&child_proc->p_flag, P_CONTROLT, relaxed);
1139 }
1140
1141 /*
1142 * block all signals to reach the process.
1143 * no transition race should be occuring with the child yet,
1144 * but indicate that the process is in (the creation) transition.
1145 */
1146 proc_signalstart(child_proc, 0);
1147 proc_transstart(child_proc, 0, 0);
1148
1149 child_proc->p_pcaction = 0;
1150
1151 TAILQ_INIT(&child_proc->p_uthlist);
1152 TAILQ_INIT(&child_proc->p_aio_activeq);
1153 TAILQ_INIT(&child_proc->p_aio_doneq);
1154
1155 /*
1156 * Copy work queue information
1157 *
1158 * Note: This should probably only happen in the case where we are
1159 * creating a child that is a copy of the parent; since this
1160 * routine is called in the non-duplication case of vfork()
1161 * or posix_spawn(), then this information should likely not
1162 * be duplicated.
1163 *
1164 * <rdar://6640553> Work queue pointers that no longer point to code
1165 */
1166 child_proc->p_wqthread = parent_proc->p_wqthread;
1167 child_proc->p_threadstart = parent_proc->p_threadstart;
1168 child_proc->p_pthsize = parent_proc->p_pthsize;
1169 if ((parent_proc->p_lflag & P_LREGISTER) != 0) {
1170 child_proc->p_lflag |= P_LREGISTER;
1171 }
1172 child_proc->p_dispatchqueue_offset = parent_proc->p_dispatchqueue_offset;
1173 child_proc->p_dispatchqueue_serialno_offset = parent_proc->p_dispatchqueue_serialno_offset;
1174 child_proc->p_dispatchqueue_label_offset = parent_proc->p_dispatchqueue_label_offset;
1175 child_proc->p_return_to_kernel_offset = parent_proc->p_return_to_kernel_offset;
1176 child_proc->p_mach_thread_self_offset = parent_proc->p_mach_thread_self_offset;
1177 child_proc->p_pth_tsd_offset = parent_proc->p_pth_tsd_offset;
1178 child_proc->p_pthread_wq_quantum_offset = parent_proc->p_pthread_wq_quantum_offset;
1179 #if PSYNCH
1180 pth_proc_hashinit(child_proc);
1181 #endif /* PSYNCH */
1182
1183 #if CONFIG_PERSONAS
1184 child_proc->p_persona = NULL;
1185 if (parent_proc->p_persona) {
1186 struct persona *persona = proc_persona_get(parent_proc);
1187
1188 if (persona) {
1189 error = persona_proc_adopt(child_proc, persona, NULL);
1190 if (error != 0) {
1191 printf("forkproc: persona_proc_inherit failed (persona %d being destroyed?)\n",
1192 persona_get_id(persona));
1193 forkproc_free(child_proc);
1194 child_proc = NULL;
1195 goto bad;
1196 }
1197 }
1198 }
1199 #endif
1200
1201 #if CONFIG_MEMORYSTATUS
1202 /* Memorystatus init */
1203 child_proc->p_memstat_state = 0;
1204 child_proc->p_memstat_effectivepriority = JETSAM_PRIORITY_DEFAULT;
1205 child_proc->p_memstat_requestedpriority = JETSAM_PRIORITY_DEFAULT;
1206 child_proc->p_memstat_assertionpriority = 0;
1207 child_proc->p_memstat_userdata = 0;
1208 child_proc->p_memstat_idle_start = 0;
1209 child_proc->p_memstat_idle_delta = 0;
1210 child_proc->p_memstat_memlimit = 0;
1211 child_proc->p_memstat_memlimit_active = 0;
1212 child_proc->p_memstat_memlimit_inactive = 0;
1213 child_proc->p_memstat_relaunch_flags = P_MEMSTAT_RELAUNCH_UNKNOWN;
1214 #if CONFIG_FREEZE
1215 child_proc->p_memstat_freeze_sharedanon_pages = 0;
1216 #endif
1217 child_proc->p_memstat_dirty = 0;
1218 child_proc->p_memstat_idledeadline = 0;
1219 #endif /* CONFIG_MEMORYSTATUS */
1220
1221 if (parent_proc->p_subsystem_root_path) {
1222 size_t parent_length = strlen(parent_proc->p_subsystem_root_path) + 1;
1223 assert(parent_length <= MAXPATHLEN);
1224 child_proc->p_subsystem_root_path = zalloc_flags(ZV_NAMEI,
1225 Z_WAITOK | Z_ZERO);
1226 memcpy(child_proc->p_subsystem_root_path, parent_proc->p_subsystem_root_path, parent_length);
1227 }
1228
1229 bad:
1230 return child_proc;
1231 }
1232
1233 void
proc_lock(proc_t p)1234 proc_lock(proc_t p)
1235 {
1236 LCK_MTX_ASSERT(&proc_list_mlock, LCK_MTX_ASSERT_NOTOWNED);
1237 lck_mtx_lock(&p->p_mlock);
1238 }
1239
1240 void
proc_unlock(proc_t p)1241 proc_unlock(proc_t p)
1242 {
1243 lck_mtx_unlock(&p->p_mlock);
1244 }
1245
1246 void
proc_spinlock(proc_t p)1247 proc_spinlock(proc_t p)
1248 {
1249 lck_spin_lock_grp(&p->p_slock, &proc_slock_grp);
1250 }
1251
1252 void
proc_spinunlock(proc_t p)1253 proc_spinunlock(proc_t p)
1254 {
1255 lck_spin_unlock(&p->p_slock);
1256 }
1257
1258 void
proc_list_lock(void)1259 proc_list_lock(void)
1260 {
1261 lck_mtx_lock(&proc_list_mlock);
1262 }
1263
1264 void
proc_list_unlock(void)1265 proc_list_unlock(void)
1266 {
1267 lck_mtx_unlock(&proc_list_mlock);
1268 }
1269
1270 void
proc_ucred_lock(proc_t p)1271 proc_ucred_lock(proc_t p)
1272 {
1273 lck_mtx_lock(&p->p_ucred_mlock);
1274 }
1275
1276 void
proc_ucred_unlock(proc_t p)1277 proc_ucred_unlock(proc_t p)
1278 {
1279 lck_mtx_unlock(&p->p_ucred_mlock);
1280 }
1281
1282 void
proc_update_creds_onproc(proc_t p,kauth_cred_t cred)1283 proc_update_creds_onproc(proc_t p, kauth_cred_t cred)
1284 {
1285 p->p_uid = kauth_cred_getuid(cred);
1286 p->p_gid = kauth_cred_getgid(cred);
1287 p->p_ruid = kauth_cred_getruid(cred);
1288 p->p_rgid = kauth_cred_getrgid(cred);
1289 p->p_svuid = kauth_cred_getsvuid(cred);
1290 p->p_svgid = kauth_cred_getsvgid(cred);
1291 }
1292
1293
1294 bool
uthread_is64bit(struct uthread * uth)1295 uthread_is64bit(struct uthread *uth)
1296 {
1297 return uth->uu_flag & UT_LP64;
1298 }
1299
1300 void
uthread_init(task_t task,uthread_t uth,thread_ro_t tro_tpl,int workq_thread)1301 uthread_init(task_t task, uthread_t uth, thread_ro_t tro_tpl, int workq_thread)
1302 {
1303 uthread_t uth_parent = current_uthread();
1304
1305 lck_spin_init(&uth->uu_rethrottle_lock, &rethrottle_lock_grp,
1306 LCK_ATTR_NULL);
1307
1308 /*
1309 * Lazily set the thread on the kernel VFS context
1310 * to the first thread made which will be vm_pageout_scan_thread.
1311 */
1312 if (__improbable(vfs_context0.vc_thread == NULL)) {
1313 extern thread_t vm_pageout_scan_thread;
1314
1315 assert(task == kernel_task);
1316 assert(get_machthread(uth) == vm_pageout_scan_thread);
1317 vfs_context0.vc_thread = get_machthread(uth);
1318 }
1319
1320 if (task_get_64bit_addr(task)) {
1321 uth->uu_flag |= UT_LP64;
1322 }
1323
1324 /*
1325 * Thread inherits credential from the creating thread, if both
1326 * are in the same task.
1327 *
1328 * If the creating thread has no credential or is from another
1329 * task we can leave the new thread credential NULL. If it needs
1330 * one later, it will be lazily assigned from the task's process.
1331 */
1332 if (task == kernel_task) {
1333 kauth_cred_set(&tro_tpl->tro_cred, vfs_context0.vc_ucred);
1334 kauth_cred_set(&tro_tpl->tro_realcred, vfs_context0.vc_ucred);
1335 tro_tpl->tro_proc = kernproc;
1336 tro_tpl->tro_proc_ro = kernproc->p_proc_ro;
1337 } else if (!task_is_a_corpse(task)) {
1338 thread_ro_t curtro = current_thread_ro();
1339 proc_t p = get_bsdtask_info(task);
1340
1341 if (task == curtro->tro_task) {
1342 kauth_cred_set(&tro_tpl->tro_realcred,
1343 curtro->tro_realcred);
1344 if (workq_thread) {
1345 kauth_cred_set(&tro_tpl->tro_cred,
1346 curtro->tro_realcred);
1347 } else {
1348 kauth_cred_set(&tro_tpl->tro_cred,
1349 curtro->tro_cred);
1350 }
1351 tro_tpl->tro_proc_ro = curtro->tro_proc_ro;
1352 } else {
1353 kauth_cred_t cred = kauth_cred_proc_ref(p);
1354 kauth_cred_set(&tro_tpl->tro_realcred, cred);
1355 kauth_cred_set(&tro_tpl->tro_cred, cred);
1356 kauth_cred_unref(&cred);
1357 tro_tpl->tro_proc_ro = task_get_ro(task);
1358 }
1359 tro_tpl->tro_proc = p;
1360
1361 proc_lock(p);
1362 if (workq_thread) {
1363 /* workq_thread threads will not inherit masks */
1364 uth->uu_sigmask = ~workq_threadmask;
1365 } else if (uth_parent->uu_flag & UT_SAS_OLDMASK) {
1366 uth->uu_sigmask = uth_parent->uu_oldmask;
1367 } else {
1368 uth->uu_sigmask = uth_parent->uu_sigmask;
1369 }
1370
1371 TAILQ_INSERT_TAIL(&p->p_uthlist, uth, uu_list);
1372 proc_unlock(p);
1373
1374 #if CONFIG_DTRACE
1375 if (p->p_dtrace_ptss_pages != NULL) {
1376 uth->t_dtrace_scratch = dtrace_ptss_claim_entry(p);
1377 }
1378 #endif
1379 } else {
1380 tro_tpl->tro_proc_ro = task_get_ro(task);
1381 }
1382
1383 uth->uu_pending_sigreturn = 0;
1384 uthread_init_proc_refcount(uth);
1385 }
1386
1387 mach_port_name_t
uthread_joiner_port(struct uthread * uth)1388 uthread_joiner_port(struct uthread *uth)
1389 {
1390 return uth->uu_save.uus_bsdthread_terminate.kport;
1391 }
1392
1393 user_addr_t
uthread_joiner_address(uthread_t uth)1394 uthread_joiner_address(uthread_t uth)
1395 {
1396 return uth->uu_save.uus_bsdthread_terminate.ulock_addr;
1397 }
1398
1399 void
uthread_joiner_wake(task_t task,uthread_t uth)1400 uthread_joiner_wake(task_t task, uthread_t uth)
1401 {
1402 struct _bsdthread_terminate bts = uth->uu_save.uus_bsdthread_terminate;
1403
1404 assert(bts.ulock_addr);
1405 bzero(&uth->uu_save.uus_bsdthread_terminate, sizeof(bts));
1406
1407 int flags = UL_UNFAIR_LOCK | ULF_WAKE_ALL | ULF_WAKE_ALLOW_NON_OWNER;
1408 (void)ulock_wake(task, flags, bts.ulock_addr, 0);
1409 mach_port_deallocate_kernel(get_task_ipcspace(task), bts.kport,
1410 IKOT_SEMAPHORE);
1411 }
1412
1413 /*
1414 * This routine frees the thread name field of the uthread_t structure. Split out of
1415 * uthread_cleanup() so thread name does not get deallocated while generating a corpse fork.
1416 */
1417 void
uthread_cleanup_name(uthread_t uth)1418 uthread_cleanup_name(uthread_t uth)
1419 {
1420 /*
1421 * <rdar://17834538>
1422 * Set pth_name to NULL before calling free().
1423 * Previously there was a race condition in the
1424 * case this code was executing during a stackshot
1425 * where the stackshot could try and copy pth_name
1426 * after it had been freed and before if was marked
1427 * as null.
1428 */
1429 if (uth->pth_name != NULL) {
1430 void *pth_name = uth->pth_name;
1431 uth->pth_name = NULL;
1432 kfree_data(pth_name, MAXTHREADNAMESIZE);
1433 }
1434 return;
1435 }
1436
1437 /*
1438 * This routine frees all the BSD context in uthread except the credential.
1439 * It does not free the uthread structure as well
1440 */
1441 void
uthread_cleanup(uthread_t uth,thread_ro_t tro)1442 uthread_cleanup(uthread_t uth, thread_ro_t tro)
1443 {
1444 task_t task = tro->tro_task;
1445 proc_t p = tro->tro_proc;
1446
1447 uthread_assert_zero_proc_refcount(uth);
1448
1449 if (uth->uu_lowpri_window || uth->uu_throttle_info) {
1450 /*
1451 * task is marked as a low priority I/O type
1452 * and we've somehow managed to not dismiss the throttle
1453 * through the normal exit paths back to user space...
1454 * no need to throttle this thread since its going away
1455 * but we do need to update our bookeeping w/r to throttled threads
1456 *
1457 * Calling this routine will clean up any throttle info reference
1458 * still inuse by the thread.
1459 */
1460 throttle_lowpri_io(0);
1461 }
1462
1463 #if CONFIG_AUDIT
1464 /*
1465 * Per-thread audit state should never last beyond system
1466 * call return. Since we don't audit the thread creation/
1467 * removal, the thread state pointer should never be
1468 * non-NULL when we get here.
1469 */
1470 assert(uth->uu_ar == NULL);
1471 #endif
1472
1473 if (uth->uu_select.nbytes) {
1474 select_cleanup_uthread(&uth->uu_select);
1475 }
1476
1477 if (uth->uu_cdir) {
1478 vnode_rele(uth->uu_cdir);
1479 uth->uu_cdir = NULLVP;
1480 }
1481
1482 if (uth->uu_selset) {
1483 select_set_free(uth->uu_selset);
1484 uth->uu_selset = NULL;
1485 }
1486
1487 os_reason_free(uth->uu_exit_reason);
1488
1489 if ((task != kernel_task) && p) {
1490 /*
1491 * Remove the thread from the process list and
1492 * transfer [appropriate] pending signals to the process.
1493 * Do not remove the uthread from proc uthlist for exec
1494 * copy task, since they does not have a ref on proc and
1495 * would not have been added to the list.
1496 */
1497 if (uth->uu_kqr_bound) {
1498 kqueue_threadreq_unbind(p, uth->uu_kqr_bound);
1499 }
1500
1501 if (get_bsdtask_info(task) == p) {
1502 proc_lock(p);
1503 TAILQ_REMOVE(&p->p_uthlist, uth, uu_list);
1504 p->p_siglist |= (uth->uu_siglist & execmask & (~p->p_sigignore | sigcantmask));
1505 proc_unlock(p);
1506 }
1507
1508 #if CONFIG_DTRACE
1509 struct dtrace_ptss_page_entry *tmpptr = uth->t_dtrace_scratch;
1510 uth->t_dtrace_scratch = NULL;
1511 if (tmpptr != NULL) {
1512 dtrace_ptss_release_entry(p, tmpptr);
1513 }
1514 #endif
1515 } else {
1516 assert(!uth->uu_kqr_bound);
1517 }
1518 }
1519
1520 /* This routine releases the credential stored in uthread */
1521 void
uthread_cred_ref(struct ucred * ucred)1522 uthread_cred_ref(struct ucred *ucred)
1523 {
1524 kauth_cred_ref(ucred);
1525 }
1526
1527 void
uthread_cred_free(struct ucred * ucred)1528 uthread_cred_free(struct ucred *ucred)
1529 {
1530 kauth_cred_set(&ucred, NOCRED);
1531 }
1532
1533 /* This routine frees the uthread structure held in thread structure */
1534 void
uthread_destroy(uthread_t uth)1535 uthread_destroy(uthread_t uth)
1536 {
1537 uthread_destroy_proc_refcount(uth);
1538
1539 if (uth->t_tombstone) {
1540 kfree_type(struct doc_tombstone, uth->t_tombstone);
1541 uth->t_tombstone = NULL;
1542 }
1543
1544 #if CONFIG_DEBUG_SYSCALL_REJECTION
1545 size_t const bitstr_len = BITMAP_SIZE(mach_trap_count + nsysent);
1546
1547 if (uth->syscall_rejection_mask) {
1548 kfree_data(uth->syscall_rejection_mask, bitstr_len);
1549 uth->syscall_rejection_mask = NULL;
1550 }
1551
1552 if (uth->syscall_rejection_once_mask) {
1553 kfree_data(uth->syscall_rejection_once_mask, bitstr_len);
1554 uth->syscall_rejection_once_mask = NULL;
1555 }
1556 #endif /* CONFIG_DEBUG_SYSCALL_REJECTION */
1557
1558 lck_spin_destroy(&uth->uu_rethrottle_lock, &rethrottle_lock_grp);
1559
1560 uthread_cleanup_name(uth);
1561 }
1562
1563 user_addr_t
thread_get_sigreturn_token(thread_t thread)1564 thread_get_sigreturn_token(thread_t thread)
1565 {
1566 uthread_t ut = (struct uthread *) get_bsdthread_info(thread);
1567 return ut->uu_sigreturn_token;
1568 }
1569
1570 uint32_t
thread_get_sigreturn_diversifier(thread_t thread)1571 thread_get_sigreturn_diversifier(thread_t thread)
1572 {
1573 uthread_t ut = (struct uthread *) get_bsdthread_info(thread);
1574 return ut->uu_sigreturn_diversifier;
1575 }
1576