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_xnu.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
411 * port movable
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.
510 *
511 * The new thread is waiting on the event triggered by 'task_clear_return_wait'
512 */
513 result = main_thread_create_waiting(child_task,
514 (thread_continue_t)task_wait_to_return,
515 task_get_return_wait_event(child_task),
516 &child_thread);
517
518 if (result != KERN_SUCCESS) {
519 printf("%s: thread_create failed. Code: %d\n",
520 __func__, result);
521 task_deallocate(child_task);
522 child_task = NULL;
523 }
524
525 /*
526 * Tag thread as being the first thread in its task.
527 */
528 thread_set_tag(child_thread, THREAD_TAG_MAINTHREAD);
529
530 bad:
531 thread_yield_internal(1);
532
533 return child_thread;
534 }
535
536
537 /*
538 * fork
539 *
540 * Description: fork system call.
541 *
542 * Parameters: parent Parent process to fork
543 * uap (void) [unused]
544 * retval Return value
545 *
546 * Returns: 0 Success
547 * EAGAIN Resource unavailable, try again
548 *
549 * Notes: Attempts to create a new child process which inherits state
550 * from the parent process. If successful, the call returns
551 * having created an initially suspended child process with an
552 * extra Mach task and thread reference, for which the thread
553 * is initially suspended. Until we resume the child process,
554 * it is not yet running.
555 *
556 * The return information to the child is contained in the
557 * thread state structure of the new child, and does not
558 * become visible to the child through a normal return process,
559 * since it never made the call into the kernel itself in the
560 * first place.
561 *
562 * After resuming the thread, this function returns directly to
563 * the parent process which invoked the fork() system call.
564 *
565 * Important: The child thread_resume occurs before the parent returns;
566 * depending on scheduling latency, this means that it is not
567 * deterministic as to whether the parent or child is scheduled
568 * to run first. It is entirely possible that the child could
569 * run to completion prior to the parent running.
570 */
571 int
fork(proc_t parent_proc,__unused struct fork_args * uap,int32_t * retval)572 fork(proc_t parent_proc, __unused struct fork_args *uap, int32_t *retval)
573 {
574 thread_t child_thread;
575 int err;
576
577 retval[1] = 0; /* flag parent return for user space */
578
579 if ((err = fork1(parent_proc, &child_thread, PROC_CREATE_FORK, NULL)) == 0) {
580 task_t child_task;
581 proc_t child_proc;
582
583 /* Return to the parent */
584 child_proc = (proc_t)get_bsdthreadtask_info(child_thread);
585 retval[0] = proc_getpid(child_proc);
586
587 child_task = (task_t)get_threadtask(child_thread);
588 assert(child_task != TASK_NULL);
589
590 task_copyout_control_port(child_task);
591 vm_map_setup(get_task_map(child_task), child_task);
592 ipc_task_enable(child_task);
593
594 /*
595 * Drop the signal lock on the child which was taken on our
596 * behalf by forkproc()/cloneproc() to prevent signals being
597 * received by the child in a partially constructed state.
598 */
599 proc_signalend(child_proc, 0);
600 proc_transend(child_proc, 0);
601
602 /* flag the fork has occurred */
603 proc_knote(parent_proc, NOTE_FORK | proc_getpid(child_proc));
604 DTRACE_PROC1(create, proc_t, child_proc);
605
606 #if CONFIG_DTRACE
607 if ((dtrace_proc_waitfor_hook = dtrace_proc_waitfor_exec_ptr) != NULL) {
608 (*dtrace_proc_waitfor_hook)(child_proc);
609 }
610 #endif
611
612 /*
613 * If current process died during the fork, the child would contain
614 * non consistent vmmap, kill the child and reap it internally.
615 */
616 if (parent_proc->p_lflag & P_LEXIT || !thread_is_active(current_thread())) {
617 task_terminate_internal(child_task);
618 proc_list_lock();
619 child_proc->p_listflag |= P_LIST_DEADPARENT;
620 proc_list_unlock();
621 }
622
623 /* "Return" to the child */
624 task_clear_return_wait(get_threadtask(child_thread), TCRW_CLEAR_ALL_WAIT);
625
626 /* drop the extra references we got during the creation */
627 task_deallocate(child_task);
628 thread_deallocate(child_thread);
629 }
630
631 return err;
632 }
633
634
635 /*
636 * cloneproc
637 *
638 * Description: Create a new process from a specified process.
639 *
640 * Parameters: parent_task The parent task to be cloned, or
641 * TASK_NULL is task characteristics
642 * are not to be inherited
643 * be cloned, or TASK_NULL if the new
644 * task is not to inherit the VM
645 * characteristics of the parent
646 * parent_proc The parent process to be cloned
647 * clone_flags Clone flags to specify if the cloned
648 * process should inherit memory,
649 * marked as memory stat internal,
650 * or if the cloneproc is called for exec.
651 *
652 * Returns: !NULL pointer to new child thread
653 * NULL Failure (unspecified)
654 *
655 * Note: On return newly created child process has signal lock held
656 * to block delivery of signal to it if called with lock set.
657 * fork() code needs to explicity remove this lock before
658 * signals can be delivered
659 *
660 * In the case of bootstrap, this function can be called from
661 * bsd_utaskbootstrap() in order to bootstrap the first process;
662 * the net effect is to provide a uthread structure for the
663 * kernel process associated with the kernel task.
664 *
665 * XXX: Tristating using the value parent_task as the major key
666 * and inherit_memory as the minor key is something we should
667 * refactor later; we owe the current semantics, ultimately,
668 * to the semantics of task_create_internal. For now, we will
669 * live with this being somewhat awkward.
670 */
671 thread_t
cloneproc(task_t parent_task,coalition_t * parent_coalitions,proc_t parent_proc,cloneproc_flags_t clone_flags)672 cloneproc(task_t parent_task, coalition_t *parent_coalitions, proc_t parent_proc, cloneproc_flags_t clone_flags)
673 {
674 #if !CONFIG_MEMORYSTATUS
675 #pragma unused(cloning_initproc)
676 #endif
677 task_t child_task;
678 proc_t child_proc;
679 thread_t child_thread = NULL;
680 bool cloning_initproc = !!(clone_flags & CLONEPROC_INITPROC);
681 bool in_exec = !!(clone_flags & CLONEPROC_EXEC);
682
683 if ((child_proc = forkproc(parent_proc, clone_flags)) == NULL) {
684 /* Failed to allocate new process */
685 goto bad;
686 }
687
688 /*
689 * In the case where the parent_task is TASK_NULL (during the init path)
690 * we make the assumption that the register size will be the same as the
691 * address space size since there's no way to determine the possible
692 * register size until an image is exec'd.
693 *
694 * The only architecture that has different address space and register sizes
695 * (arm64_32) isn't being used within kernel-space, so the above assumption
696 * always holds true for the init path.
697 */
698 const int parent_64bit_addr = parent_proc->p_flag & P_LP64;
699 const int parent_64bit_data = (parent_task == TASK_NULL) ? parent_64bit_addr : task_get_64bit_data(parent_task);
700
701 child_thread = fork_create_child(parent_task,
702 parent_coalitions,
703 child_proc,
704 parent_64bit_addr,
705 parent_64bit_data,
706 clone_flags);
707
708 if (child_thread == NULL) {
709 /*
710 * Failed to create thread; now we must deconstruct the new
711 * process previously obtained from forkproc().
712 */
713 forkproc_free(child_proc);
714 goto bad;
715 }
716
717 child_task = get_threadtask(child_thread);
718 if (parent_64bit_addr) {
719 OSBitOrAtomic(P_LP64, (UInt32 *)&child_proc->p_flag);
720 get_bsdthread_info(child_thread)->uu_flag |= UT_LP64;
721 } else {
722 OSBitAndAtomic(~((uint32_t)P_LP64), (UInt32 *)&child_proc->p_flag);
723 get_bsdthread_info(child_thread)->uu_flag &= ~UT_LP64;
724 }
725
726 #if CONFIG_MEMORYSTATUS
727 if (cloning_initproc ||
728 (in_exec && (parent_proc->p_memstat_state & P_MEMSTAT_INTERNAL))) {
729 proc_list_lock();
730 child_proc->p_memstat_state |= P_MEMSTAT_INTERNAL;
731 child_proc->p_memstat_effectivepriority = JETSAM_PRIORITY_INTERNAL;
732 child_proc->p_memstat_requestedpriority = JETSAM_PRIORITY_INTERNAL;
733 proc_list_unlock();
734 }
735 if (in_exec && parent_proc->p_memstat_relaunch_flags != P_MEMSTAT_RELAUNCH_UNKNOWN) {
736 memorystatus_relaunch_flags_update(child_proc, parent_proc->p_memstat_relaunch_flags);
737 }
738 #endif
739
740 /* make child visible */
741 pinsertchild(parent_proc, child_proc, in_exec);
742
743 /*
744 * Make child runnable, set start time.
745 */
746 child_proc->p_stat = SRUN;
747 bad:
748 return child_thread;
749 }
750
751 void
proc_set_sigact(proc_t p,int sig,user_addr_t sigact)752 proc_set_sigact(proc_t p, int sig, user_addr_t sigact)
753 {
754 assert((sig > 0) && (sig < NSIG));
755
756 p->p_sigacts.ps_sigact[sig] = sigact;
757 }
758
759 void
proc_set_trampact(proc_t p,int sig,user_addr_t trampact)760 proc_set_trampact(proc_t p, int sig, user_addr_t trampact)
761 {
762 assert((sig > 0) && (sig < NSIG));
763
764 p->p_sigacts.ps_trampact[sig] = trampact;
765 }
766
767 void
proc_set_sigact_trampact(proc_t p,int sig,user_addr_t sigact,user_addr_t trampact)768 proc_set_sigact_trampact(proc_t p, int sig, user_addr_t sigact, user_addr_t trampact)
769 {
770 assert((sig > 0) && (sig < NSIG));
771
772 p->p_sigacts.ps_sigact[sig] = sigact;
773 p->p_sigacts.ps_trampact[sig] = trampact;
774 }
775
776 void
proc_reset_sigact(proc_t p,sigset_t sigs)777 proc_reset_sigact(proc_t p, sigset_t sigs)
778 {
779 user_addr_t *sigacts = p->p_sigacts.ps_sigact;
780 int nc;
781
782 while (sigs) {
783 nc = ffs((unsigned int)sigs);
784 if (sigacts[nc] != SIG_DFL) {
785 sigacts[nc] = SIG_DFL;
786 }
787 sigs &= ~sigmask(nc);
788 }
789 }
790
791 /*
792 * Destroy a process structure that resulted from a call to forkproc(), but
793 * which must be returned to the system because of a subsequent failure
794 * preventing it from becoming active.
795 *
796 * Parameters: p The incomplete process from forkproc()
797 *
798 * Returns: (void)
799 *
800 * Note: This function should only be used in an error handler following
801 * a call to forkproc().
802 *
803 * Operations occur in reverse order of those in forkproc().
804 */
805 void
forkproc_free(proc_t p)806 forkproc_free(proc_t p)
807 {
808 struct pgrp *pg;
809
810 #if CONFIG_PERSONAS
811 persona_proc_drop(p);
812 #endif /* CONFIG_PERSONAS */
813
814 #if PSYNCH
815 pth_proc_hashdelete(p);
816 #endif /* PSYNCH */
817
818 /* We held signal and a transition locks; drop them */
819 proc_signalend(p, 0);
820 proc_transend(p, 0);
821
822 /*
823 * If we have our own copy of the resource limits structure, we
824 * need to free it. If it's a shared copy, we need to drop our
825 * reference on it.
826 */
827 proc_limitdrop(p);
828
829 #if SYSV_SHM
830 /* Need to drop references to the shared memory segment(s), if any */
831 if (p->vm_shm) {
832 /*
833 * Use shmexec(): we have no address space, so no mappings
834 *
835 * XXX Yes, the routine is badly named.
836 */
837 shmexec(p);
838 }
839 #endif
840
841 /* Need to undo the effects of the fdt_fork(), if any */
842 fdt_invalidate(p);
843 fdt_destroy(p);
844
845 /*
846 * Drop the reference on a text vnode pointer, if any
847 * XXX This code is broken in forkproc(); see <rdar://4256419>;
848 * XXX if anyone ever uses this field, we will be extremely unhappy.
849 */
850 if (p->p_textvp) {
851 vnode_rele(p->p_textvp);
852 p->p_textvp = NULL;
853 }
854
855 /* Update the audit session proc count */
856 AUDIT_SESSION_PROCEXIT(p);
857
858 lck_mtx_destroy(&p->p_mlock, &proc_mlock_grp);
859 lck_mtx_destroy(&p->p_ucred_mlock, &proc_ucred_mlock_grp);
860 #if CONFIG_AUDIT
861 lck_mtx_destroy(&p->p_audit_mlock, &proc_ucred_mlock_grp);
862 #endif /* CONFIG_AUDIT */
863 #if CONFIG_DTRACE
864 lck_mtx_destroy(&p->p_dtrace_sprlock, &proc_lck_grp);
865 #endif
866 lck_spin_destroy(&p->p_slock, &proc_slock_grp);
867
868 proc_list_lock();
869 /* Decrement the count of processes in the system */
870 nprocs--;
871
872 /* quit the group */
873 pg = pgrp_leave_locked(p);
874
875 /* Take it out of process hash */
876 assert((os_ref_get_raw_mask(&p->p_refcount) >> P_REF_BITS) == 1);
877 assert((os_ref_get_raw_mask(&p->p_refcount) & P_REF_NEW) == P_REF_NEW);
878 os_atomic_xor(&p->p_refcount, P_REF_NEW | P_REF_DEAD, relaxed);
879
880 /* Remove from hash if not a shadow proc */
881 if (!proc_is_shadow(p)) {
882 phash_remove_locked(p);
883 }
884
885 proc_list_unlock();
886
887 pgrp_rele(pg);
888
889 thread_call_free(p->p_rcall);
890
891 /* Free allocated memory */
892 zfree(proc_stats_zone, p->p_stats);
893 p->p_stats = NULL;
894 if (p->p_subsystem_root_path) {
895 zfree(ZV_NAMEI, p->p_subsystem_root_path);
896 p->p_subsystem_root_path = NULL;
897 }
898
899 proc_checkdeadrefs(p);
900 proc_wait_release(p);
901 }
902
903
904 /*
905 * forkproc
906 *
907 * Description: Create a new process structure, given a parent process
908 * structure.
909 *
910 * Parameters: parent_proc The parent process
911 *
912 * Returns: !NULL The new process structure
913 * NULL Error (insufficient free memory)
914 *
915 * Note: When successful, the newly created process structure is
916 * partially initialized; if a caller needs to deconstruct the
917 * returned structure, they must call forkproc_free() to do so.
918 */
919 proc_t
forkproc(proc_t parent_proc,cloneproc_flags_t clone_flags)920 forkproc(proc_t parent_proc, cloneproc_flags_t clone_flags)
921 {
922 static uint64_t nextuniqueid = 0;
923 static pid_t lastpid = 0;
924
925 proc_t child_proc; /* Our new process */
926 int error = 0;
927 struct pgrp *pg;
928 uthread_t parent_uthread = current_uthread();
929 rlim_t rlimit_cpu_cur;
930 pid_t pid;
931 struct proc_ro_data proc_ro_data = {};
932 bool in_exec = !!(clone_flags & CLONEPROC_EXEC);
933 bool in_fork = !!(clone_flags & CLONEPROC_FORK);
934
935 child_proc = zalloc_flags(proc_task_zone, Z_WAITOK | Z_ZERO);
936
937 child_proc->p_stats = zalloc_flags(proc_stats_zone, Z_WAITOK | Z_ZERO);
938 child_proc->p_sigacts = parent_proc->p_sigacts;
939 os_ref_init_mask(&child_proc->p_refcount, P_REF_BITS, &p_refgrp, P_REF_NEW);
940 os_ref_init_raw(&child_proc->p_waitref, &p_refgrp);
941 proc_ref_hold_proc_task_struct(child_proc);
942
943 /* allocate a callout for use by interval timers */
944 child_proc->p_rcall = thread_call_allocate((thread_call_func_t)realitexpire, child_proc);
945
946 /*
947 * Find an unused PID.
948 */
949
950 fdt_init(child_proc);
951
952 proc_list_lock();
953
954 if (!in_exec) {
955 pid = lastpid;
956 do {
957 /*
958 * If the process ID prototype has wrapped around,
959 * restart somewhat above 0, as the low-numbered procs
960 * tend to include daemons that don't exit.
961 */
962 if (++pid >= PID_MAX) {
963 pid = 100;
964 }
965 if (pid == lastpid) {
966 panic("Unable to allocate a new pid");
967 }
968
969 /* if the pid stays in hash both for zombie and runniing state */
970 } while (phash_find_locked(pid) != PROC_NULL ||
971 pghash_exists_locked(pid) ||
972 session_find_locked(pid) != SESSION_NULL);
973
974 lastpid = pid;
975 nprocs++;
976
977 child_proc->p_pid = pid;
978 proc_ro_data.p_idversion = OSIncrementAtomic(&nextpidversion);
979 /* kernel process is handcrafted and not from fork, so start from 1 */
980 proc_ro_data.p_uniqueid = ++nextuniqueid;
981 /* Retain our parent's current pid and pidversion */
982 proc_ro_data.p_orig_ppid = proc_getpid(parent_proc);
983 proc_ro_data.p_orig_ppidversion = proc_pidversion(parent_proc);
984
985 /* Insert in the hash, and inherit our group (and session) */
986 phash_insert_locked(child_proc);
987
988 /* Check if the proc is from App Cryptex */
989 if (parent_proc->p_ladvflag & P_RSR) {
990 os_atomic_or(&child_proc->p_ladvflag, P_RSR, relaxed);
991 }
992 } else {
993 /* For exec copy of the proc, copy the PID identifiers of original proc */
994 pid = parent_proc->p_pid;
995 child_proc->p_pid = pid;
996 proc_ro_data.p_idversion = parent_proc->p_proc_ro->p_idversion;
997 proc_ro_data.p_uniqueid = parent_proc->p_proc_ro->p_uniqueid;
998 proc_ro_data.p_orig_ppid = proc_original_ppid(parent_proc);
999 proc_ro_data.p_orig_ppidversion = proc_orig_ppidversion(parent_proc);
1000
1001 nprocs++;
1002 os_atomic_or(&child_proc->p_refcount, P_REF_SHADOW, relaxed);
1003 }
1004 pg = pgrp_enter_locked(parent_proc, child_proc);
1005 proc_list_unlock();
1006
1007 if (proc_ro_data.p_uniqueid == startup_serial_num_procs) {
1008 /*
1009 * Turn off startup serial logging now that we have reached
1010 * the defined number of startup processes.
1011 */
1012 startup_serial_logging_active = false;
1013 }
1014
1015 /*
1016 * We've identified the PID we are going to use;
1017 * initialize the new process structure.
1018 */
1019 child_proc->p_stat = SIDL;
1020
1021 /*
1022 * The zero'ing of the proc was at the allocation time due to need
1023 * for insertion to hash. Copy the section that is to be copied
1024 * directly from the parent.
1025 */
1026 child_proc->p_forkcopy = parent_proc->p_forkcopy;
1027
1028 proc_ro_data.syscall_filter_mask = proc_syscall_filter_mask(parent_proc);
1029 proc_ro_data.p_platform_data = proc_get_ro(parent_proc)->p_platform_data;
1030
1031 /*
1032 * Some flags are inherited from the parent.
1033 * Duplicate sub-structures as needed.
1034 * Increase reference counts on shared objects.
1035 * The p_stats substruct is set in vm_fork.
1036 */
1037 #if CONFIG_DELAY_IDLE_SLEEP
1038 child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_DISABLE_ASLR | P_DELAYIDLESLEEP | P_SUGID | P_AFFINITY));
1039 #else /* CONFIG_DELAY_IDLE_SLEEP */
1040 child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_DISABLE_ASLR | P_SUGID | P_AFFINITY));
1041 #endif /* CONFIG_DELAY_IDLE_SLEEP */
1042
1043 child_proc->p_vfs_iopolicy = (parent_proc->p_vfs_iopolicy & (P_VFS_IOPOLICY_INHERITED_MASK));
1044
1045 proc_set_responsible_pid(child_proc, parent_proc->p_responsible_pid);
1046
1047 /*
1048 * Note that if the current thread has an assumed identity, this
1049 * credential will be granted to the new process.
1050 * This is OK to do in exec, because it will be over-written during image activation
1051 * before the proc is visible.
1052 */
1053 kauth_cred_set(&proc_ro_data.p_ucred.__smr_ptr, kauth_cred_get());
1054
1055 lck_mtx_init(&child_proc->p_mlock, &proc_mlock_grp, &proc_lck_attr);
1056 lck_mtx_init(&child_proc->p_ucred_mlock, &proc_ucred_mlock_grp, &proc_lck_attr);
1057 #if CONFIG_AUDIT
1058 lck_mtx_init(&child_proc->p_audit_mlock, &proc_ucred_mlock_grp, &proc_lck_attr);
1059 #endif /* CONFIG_AUDIT */
1060 #if CONFIG_DTRACE
1061 lck_mtx_init(&child_proc->p_dtrace_sprlock, &proc_lck_grp, &proc_lck_attr);
1062 #endif
1063 lck_spin_init(&child_proc->p_slock, &proc_slock_grp, &proc_lck_attr);
1064
1065 klist_init(&child_proc->p_klist);
1066
1067 if (child_proc->p_textvp != NULLVP) {
1068 /* bump references to the text vnode */
1069 /* Need to hold iocount across the ref call */
1070 if ((error = vnode_getwithref(child_proc->p_textvp)) == 0) {
1071 error = vnode_ref(child_proc->p_textvp);
1072 vnode_put(child_proc->p_textvp);
1073 }
1074
1075 if (error != 0) {
1076 child_proc->p_textvp = NULLVP;
1077 }
1078 }
1079 uint64_t csflag_inherit_mask = ~CS_KILLED;
1080 if (!in_fork) {
1081 /* All non-fork paths should not inherit GTA flag */
1082 csflag_inherit_mask &= ~CS_GET_TASK_ALLOW;
1083 }
1084 proc_ro_data.p_csflags = ((uint32_t)proc_getcsflags(parent_proc) & csflag_inherit_mask);
1085
1086 child_proc->p_proc_ro = proc_ro_alloc(child_proc, &proc_ro_data, NULL, NULL);
1087
1088 /* update cred on proc */
1089 proc_update_creds_onproc(child_proc, proc_ucred_unsafe(child_proc));
1090
1091 /* update audit session proc count */
1092 AUDIT_SESSION_PROCNEW(child_proc);
1093
1094 /*
1095 * Copy the parents per process open file table to the child; if
1096 * there is a per-thread current working directory, set the childs
1097 * per-process current working directory to that instead of the
1098 * parents.
1099 */
1100 if (fdt_fork(&child_proc->p_fd, parent_proc, parent_uthread->uu_cdir, in_exec) != 0) {
1101 forkproc_free(child_proc);
1102 child_proc = NULL;
1103 goto bad;
1104 }
1105
1106 #if SYSV_SHM
1107 if (parent_proc->vm_shm && !in_exec) {
1108 /* XXX may fail to attach shm to child */
1109 (void)shmfork(parent_proc, child_proc);
1110 }
1111 #endif
1112
1113 /*
1114 * Child inherits the parent's plimit
1115 */
1116 proc_limitfork(parent_proc, child_proc);
1117
1118 rlimit_cpu_cur = proc_limitgetcur(child_proc, RLIMIT_CPU);
1119 if (rlimit_cpu_cur != RLIM_INFINITY) {
1120 child_proc->p_rlim_cpu.tv_sec = (rlimit_cpu_cur > __INT_MAX__) ? __INT_MAX__ : rlimit_cpu_cur;
1121 }
1122
1123 if (in_exec) {
1124 /* Keep the original start time for exec'ed proc */
1125 child_proc->p_stats->ps_start = parent_proc->p_stats->ps_start;
1126 child_proc->p_start.tv_sec = parent_proc->p_start.tv_sec;
1127 child_proc->p_start.tv_usec = parent_proc->p_start.tv_usec;
1128 } else {
1129 /* Intialize new process stats, including start time */
1130 /* <rdar://6640543> non-zeroed portion contains garbage AFAICT */
1131 microtime_with_abstime(&child_proc->p_start, &child_proc->p_stats->ps_start);
1132 }
1133
1134 if (pg->pg_session->s_ttyvp != NULL && parent_proc->p_flag & P_CONTROLT) {
1135 os_atomic_or(&child_proc->p_flag, P_CONTROLT, relaxed);
1136 }
1137
1138 /*
1139 * block all signals to reach the process.
1140 * no transition race should be occuring with the child yet,
1141 * but indicate that the process is in (the creation) transition.
1142 */
1143 proc_signalstart(child_proc, 0);
1144 proc_transstart(child_proc, 0, 0);
1145
1146 child_proc->p_pcaction = 0;
1147
1148 TAILQ_INIT(&child_proc->p_uthlist);
1149 TAILQ_INIT(&child_proc->p_aio_activeq);
1150 TAILQ_INIT(&child_proc->p_aio_doneq);
1151
1152 /*
1153 * Copy work queue information
1154 *
1155 * Note: This should probably only happen in the case where we are
1156 * creating a child that is a copy of the parent; since this
1157 * routine is called in the non-duplication case of vfork()
1158 * or posix_spawn(), then this information should likely not
1159 * be duplicated.
1160 *
1161 * <rdar://6640553> Work queue pointers that no longer point to code
1162 */
1163 child_proc->p_wqthread = parent_proc->p_wqthread;
1164 child_proc->p_threadstart = parent_proc->p_threadstart;
1165 child_proc->p_pthsize = parent_proc->p_pthsize;
1166 if ((parent_proc->p_lflag & P_LREGISTER) != 0) {
1167 child_proc->p_lflag |= P_LREGISTER;
1168 }
1169 child_proc->p_dispatchqueue_offset = parent_proc->p_dispatchqueue_offset;
1170 child_proc->p_dispatchqueue_serialno_offset = parent_proc->p_dispatchqueue_serialno_offset;
1171 child_proc->p_dispatchqueue_label_offset = parent_proc->p_dispatchqueue_label_offset;
1172 child_proc->p_return_to_kernel_offset = parent_proc->p_return_to_kernel_offset;
1173 child_proc->p_mach_thread_self_offset = parent_proc->p_mach_thread_self_offset;
1174 child_proc->p_pth_tsd_offset = parent_proc->p_pth_tsd_offset;
1175 child_proc->p_pthread_wq_quantum_offset = parent_proc->p_pthread_wq_quantum_offset;
1176 #if PSYNCH
1177 pth_proc_hashinit(child_proc);
1178 #endif /* PSYNCH */
1179
1180 #if CONFIG_PERSONAS
1181 child_proc->p_persona = NULL;
1182 if (parent_proc->p_persona) {
1183 struct persona *persona = proc_persona_get(parent_proc);
1184
1185 if (persona) {
1186 error = persona_proc_adopt(child_proc, persona, NULL);
1187 if (error != 0) {
1188 printf("forkproc: persona_proc_inherit failed (persona %d being destroyed?)\n",
1189 persona_get_id(persona));
1190 forkproc_free(child_proc);
1191 child_proc = NULL;
1192 goto bad;
1193 }
1194 }
1195 }
1196 #endif
1197
1198 #if CONFIG_MEMORYSTATUS
1199 /* Memorystatus init */
1200 child_proc->p_memstat_state = 0;
1201 child_proc->p_memstat_effectivepriority = JETSAM_PRIORITY_DEFAULT;
1202 child_proc->p_memstat_requestedpriority = JETSAM_PRIORITY_DEFAULT;
1203 child_proc->p_memstat_assertionpriority = 0;
1204 child_proc->p_memstat_userdata = 0;
1205 child_proc->p_memstat_prio_start = mach_absolute_time();
1206 child_proc->p_memstat_idle_delta = 0;
1207 child_proc->p_memstat_memlimit = 0;
1208 child_proc->p_memstat_memlimit_active = 0;
1209 child_proc->p_memstat_memlimit_inactive = 0;
1210 child_proc->p_memstat_relaunch_flags = P_MEMSTAT_RELAUNCH_UNKNOWN;
1211 #if CONFIG_FREEZE
1212 child_proc->p_memstat_freeze_sharedanon_pages = 0;
1213 #endif
1214 child_proc->p_memstat_dirty = 0;
1215 child_proc->p_memstat_idledeadline = 0;
1216 #endif /* CONFIG_MEMORYSTATUS */
1217
1218 if (parent_proc->p_subsystem_root_path) {
1219 size_t parent_length = strlen(parent_proc->p_subsystem_root_path) + 1;
1220 assert(parent_length <= MAXPATHLEN);
1221 child_proc->p_subsystem_root_path = zalloc_flags(ZV_NAMEI,
1222 Z_WAITOK | Z_ZERO);
1223 memcpy(child_proc->p_subsystem_root_path, parent_proc->p_subsystem_root_path, parent_length);
1224 }
1225
1226 bad:
1227 return child_proc;
1228 }
1229
1230 void
proc_lock(proc_t p)1231 proc_lock(proc_t p)
1232 {
1233 LCK_MTX_ASSERT(&proc_list_mlock, LCK_MTX_ASSERT_NOTOWNED);
1234 lck_mtx_lock(&p->p_mlock);
1235 }
1236
1237 void
proc_unlock(proc_t p)1238 proc_unlock(proc_t p)
1239 {
1240 lck_mtx_unlock(&p->p_mlock);
1241 }
1242
1243 void
proc_spinlock(proc_t p)1244 proc_spinlock(proc_t p)
1245 {
1246 lck_spin_lock_grp(&p->p_slock, &proc_slock_grp);
1247 }
1248
1249 void
proc_spinunlock(proc_t p)1250 proc_spinunlock(proc_t p)
1251 {
1252 lck_spin_unlock(&p->p_slock);
1253 }
1254
1255 void
proc_list_lock(void)1256 proc_list_lock(void)
1257 {
1258 lck_mtx_lock(&proc_list_mlock);
1259 }
1260
1261 void
proc_list_unlock(void)1262 proc_list_unlock(void)
1263 {
1264 lck_mtx_unlock(&proc_list_mlock);
1265 }
1266
1267 void
proc_ucred_lock(proc_t p)1268 proc_ucred_lock(proc_t p)
1269 {
1270 lck_mtx_lock(&p->p_ucred_mlock);
1271 }
1272
1273 void
proc_ucred_unlock(proc_t p)1274 proc_ucred_unlock(proc_t p)
1275 {
1276 lck_mtx_unlock(&p->p_ucred_mlock);
1277 }
1278
1279 void
proc_update_creds_onproc(proc_t p,kauth_cred_t cred)1280 proc_update_creds_onproc(proc_t p, kauth_cred_t cred)
1281 {
1282 p->p_uid = kauth_cred_getuid(cred);
1283 p->p_gid = kauth_cred_getgid(cred);
1284 p->p_ruid = kauth_cred_getruid(cred);
1285 p->p_rgid = kauth_cred_getrgid(cred);
1286 p->p_svuid = kauth_cred_getsvuid(cred);
1287 p->p_svgid = kauth_cred_getsvgid(cred);
1288 }
1289
1290
1291 bool
uthread_is64bit(struct uthread * uth)1292 uthread_is64bit(struct uthread *uth)
1293 {
1294 return uth->uu_flag & UT_LP64;
1295 }
1296
1297 void
uthread_init(task_t task,uthread_t uth,thread_ro_t tro_tpl,int workq_thread)1298 uthread_init(task_t task, uthread_t uth, thread_ro_t tro_tpl, int workq_thread)
1299 {
1300 uthread_t uth_parent = current_uthread();
1301
1302 lck_spin_init(&uth->uu_rethrottle_lock, &rethrottle_lock_grp,
1303 LCK_ATTR_NULL);
1304
1305 /*
1306 * Lazily set the thread on the kernel VFS context
1307 * to the first thread made which will be vm_pageout_scan_thread.
1308 */
1309 if (__improbable(vfs_context0.vc_thread == NULL)) {
1310 extern thread_t vm_pageout_scan_thread;
1311
1312 assert(task == kernel_task);
1313 assert(get_machthread(uth) == vm_pageout_scan_thread);
1314 vfs_context0.vc_thread = get_machthread(uth);
1315 }
1316
1317 if (task_get_64bit_addr(task)) {
1318 uth->uu_flag |= UT_LP64;
1319 }
1320
1321 /*
1322 * Thread inherits credential from the creating thread, if both
1323 * are in the same task.
1324 *
1325 * If the creating thread has no credential or is from another
1326 * task we can leave the new thread credential NULL. If it needs
1327 * one later, it will be lazily assigned from the task's process.
1328 */
1329 if (task == kernel_task) {
1330 kauth_cred_set(&tro_tpl->tro_cred, vfs_context0.vc_ucred);
1331 kauth_cred_set(&tro_tpl->tro_realcred, vfs_context0.vc_ucred);
1332 tro_tpl->tro_proc = kernproc;
1333 tro_tpl->tro_proc_ro = kernproc->p_proc_ro;
1334 } else if (!task_is_a_corpse(task)) {
1335 thread_ro_t curtro = current_thread_ro();
1336 proc_t p = get_bsdtask_info(task);
1337
1338 if (task == curtro->tro_task) {
1339 kauth_cred_set(&tro_tpl->tro_realcred,
1340 curtro->tro_realcred);
1341 if (workq_thread) {
1342 kauth_cred_set(&tro_tpl->tro_cred,
1343 curtro->tro_realcred);
1344 } else {
1345 kauth_cred_set(&tro_tpl->tro_cred,
1346 curtro->tro_cred);
1347 }
1348 tro_tpl->tro_proc_ro = curtro->tro_proc_ro;
1349 } else {
1350 kauth_cred_t cred = kauth_cred_proc_ref(p);
1351 kauth_cred_set(&tro_tpl->tro_realcred, cred);
1352 kauth_cred_set(&tro_tpl->tro_cred, cred);
1353 kauth_cred_unref(&cred);
1354 tro_tpl->tro_proc_ro = task_get_ro(task);
1355 }
1356 tro_tpl->tro_proc = p;
1357
1358 proc_lock(p);
1359 if (workq_thread) {
1360 /* workq_thread threads will not inherit masks */
1361 uth->uu_sigmask = ~workq_threadmask;
1362 } else if (uth_parent->uu_flag & UT_SAS_OLDMASK) {
1363 uth->uu_sigmask = uth_parent->uu_oldmask;
1364 } else {
1365 uth->uu_sigmask = uth_parent->uu_sigmask;
1366 }
1367
1368 TAILQ_INSERT_TAIL(&p->p_uthlist, uth, uu_list);
1369 proc_unlock(p);
1370
1371 #if CONFIG_DTRACE
1372 if (p->p_dtrace_ptss_pages != NULL) {
1373 uth->t_dtrace_scratch = dtrace_ptss_claim_entry(p);
1374 }
1375 #endif
1376 } else {
1377 tro_tpl->tro_proc_ro = task_get_ro(task);
1378 }
1379
1380 uth->uu_pending_sigreturn = 0;
1381 uthread_init_proc_refcount(uth);
1382 }
1383
1384 mach_port_name_t
uthread_joiner_port(struct uthread * uth)1385 uthread_joiner_port(struct uthread *uth)
1386 {
1387 return uth->uu_save.uus_bsdthread_terminate.kport;
1388 }
1389
1390 user_addr_t
uthread_joiner_address(uthread_t uth)1391 uthread_joiner_address(uthread_t uth)
1392 {
1393 return uth->uu_save.uus_bsdthread_terminate.ulock_addr;
1394 }
1395
1396 void
uthread_joiner_wake(task_t task,uthread_t uth)1397 uthread_joiner_wake(task_t task, uthread_t uth)
1398 {
1399 struct _bsdthread_terminate bts = uth->uu_save.uus_bsdthread_terminate;
1400
1401 assert(bts.ulock_addr);
1402 bzero(&uth->uu_save.uus_bsdthread_terminate, sizeof(bts));
1403
1404 int flags = UL_UNFAIR_LOCK | ULF_WAKE_ALL | ULF_WAKE_ALLOW_NON_OWNER;
1405 (void)ulock_wake(task, flags, bts.ulock_addr, 0);
1406 mach_port_deallocate_kernel(get_task_ipcspace(task), bts.kport,
1407 IKOT_SEMAPHORE);
1408 }
1409
1410 /*
1411 * This routine frees the thread name field of the uthread_t structure. Split out of
1412 * uthread_cleanup() so thread name does not get deallocated while generating a corpse fork.
1413 */
1414 void
uthread_cleanup_name(uthread_t uth)1415 uthread_cleanup_name(uthread_t uth)
1416 {
1417 /*
1418 * <rdar://17834538>
1419 * Set pth_name to NULL before calling free().
1420 * Previously there was a race condition in the
1421 * case this code was executing during a stackshot
1422 * where the stackshot could try and copy pth_name
1423 * after it had been freed and before if was marked
1424 * as null.
1425 */
1426 if (uth->pth_name != NULL) {
1427 void *pth_name = uth->pth_name;
1428 uth->pth_name = NULL;
1429 kfree_data(pth_name, MAXTHREADNAMESIZE);
1430 }
1431 return;
1432 }
1433
1434 /*
1435 * This routine frees all the BSD context in uthread except the credential.
1436 * It does not free the uthread structure as well
1437 */
1438 void
uthread_cleanup(uthread_t uth,thread_ro_t tro)1439 uthread_cleanup(uthread_t uth, thread_ro_t tro)
1440 {
1441 task_t task = tro->tro_task;
1442 proc_t p = tro->tro_proc;
1443
1444 uthread_assert_zero_proc_refcount(uth);
1445
1446 if (uth->uu_lowpri_window || uth->uu_throttle_info) {
1447 /*
1448 * task is marked as a low priority I/O type
1449 * and we've somehow managed to not dismiss the throttle
1450 * through the normal exit paths back to user space...
1451 * no need to throttle this thread since its going away
1452 * but we do need to update our bookeeping w/r to throttled threads
1453 *
1454 * Calling this routine will clean up any throttle info reference
1455 * still inuse by the thread.
1456 */
1457 throttle_lowpri_io(0);
1458 }
1459
1460 #if CONFIG_AUDIT
1461 /*
1462 * Per-thread audit state should never last beyond system
1463 * call return. Since we don't audit the thread creation/
1464 * removal, the thread state pointer should never be
1465 * non-NULL when we get here.
1466 */
1467 assert(uth->uu_ar == NULL);
1468 #endif
1469
1470 if (uth->uu_select.nbytes) {
1471 select_cleanup_uthread(&uth->uu_select);
1472 }
1473
1474 if (uth->uu_cdir) {
1475 vnode_rele(uth->uu_cdir);
1476 uth->uu_cdir = NULLVP;
1477 }
1478
1479 if (uth->uu_selset) {
1480 select_set_free(uth->uu_selset);
1481 uth->uu_selset = NULL;
1482 }
1483
1484 os_reason_free(uth->uu_exit_reason);
1485
1486 if ((task != kernel_task) && p) {
1487 /*
1488 * Remove the thread from the process list and
1489 * transfer [appropriate] pending signals to the process.
1490 * Do not remove the uthread from proc uthlist for exec
1491 * copy task, since they does not have a ref on proc and
1492 * would not have been added to the list.
1493 */
1494 if (uth->uu_kqr_bound) {
1495 kqueue_threadreq_unbind(p, uth->uu_kqr_bound);
1496 }
1497
1498 if (get_bsdtask_info(task) == p) {
1499 proc_lock(p);
1500 TAILQ_REMOVE(&p->p_uthlist, uth, uu_list);
1501 p->p_siglist |= (uth->uu_siglist & execmask & (~p->p_sigignore | sigcantmask));
1502 proc_unlock(p);
1503 }
1504
1505 #if CONFIG_DTRACE
1506 struct dtrace_ptss_page_entry *tmpptr = uth->t_dtrace_scratch;
1507 uth->t_dtrace_scratch = NULL;
1508 if (tmpptr != NULL) {
1509 dtrace_ptss_release_entry(p, tmpptr);
1510 }
1511 #endif
1512 } else {
1513 assert(!uth->uu_kqr_bound);
1514 }
1515 }
1516
1517 /* This routine releases the credential stored in uthread */
1518 void
uthread_cred_ref(struct ucred * ucred)1519 uthread_cred_ref(struct ucred *ucred)
1520 {
1521 kauth_cred_ref(ucred);
1522 }
1523
1524 void
uthread_cred_free(struct ucred * ucred)1525 uthread_cred_free(struct ucred *ucred)
1526 {
1527 kauth_cred_set(&ucred, NOCRED);
1528 }
1529
1530 /* This routine frees the uthread structure held in thread structure */
1531 void
uthread_destroy(uthread_t uth)1532 uthread_destroy(uthread_t uth)
1533 {
1534 uthread_destroy_proc_refcount(uth);
1535
1536 if (uth->t_tombstone) {
1537 kfree_type(struct doc_tombstone, uth->t_tombstone);
1538 uth->t_tombstone = NULL;
1539 }
1540
1541 #if CONFIG_DEBUG_SYSCALL_REJECTION
1542 size_t const bitstr_len = BITMAP_SIZE(mach_trap_count + nsysent);
1543
1544 if (uth->syscall_rejection_mask) {
1545 kfree_data(uth->syscall_rejection_mask, bitstr_len);
1546 uth->syscall_rejection_mask = NULL;
1547 }
1548
1549 if (uth->syscall_rejection_once_mask) {
1550 kfree_data(uth->syscall_rejection_once_mask, bitstr_len);
1551 uth->syscall_rejection_once_mask = NULL;
1552 }
1553 #endif /* CONFIG_DEBUG_SYSCALL_REJECTION */
1554
1555 lck_spin_destroy(&uth->uu_rethrottle_lock, &rethrottle_lock_grp);
1556
1557 uthread_cleanup_name(uth);
1558 }
1559
1560 user_addr_t
thread_get_sigreturn_token(thread_t thread)1561 thread_get_sigreturn_token(thread_t thread)
1562 {
1563 uthread_t ut = (struct uthread *) get_bsdthread_info(thread);
1564 return ut->uu_sigreturn_token;
1565 }
1566
1567 uint32_t
thread_get_sigreturn_diversifier(thread_t thread)1568 thread_get_sigreturn_diversifier(thread_t thread)
1569 {
1570 uthread_t ut = (struct uthread *) get_bsdthread_info(thread);
1571 return ut->uu_sigreturn_diversifier;
1572 }
1573