1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1989, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #include "opt_ktrace.h"
38 #include "opt_kstack_pages.h"
39
40 #define EXTERR_CATEGORY EXTERR_CAT_FORK
41 #include <sys/systm.h>
42 #include <sys/acct.h>
43 #include <sys/bitstring.h>
44 #include <sys/capsicum.h>
45 #include <sys/eventhandler.h>
46 #include <sys/exterrvar.h>
47 #include <sys/fcntl.h>
48 #include <sys/filedesc.h>
49 #include <sys/jail.h>
50 #include <sys/kernel.h>
51 #include <sys/kthread.h>
52 #include <sys/ktr.h>
53 #include <sys/ktrace.h>
54 #include <sys/sysctl.h>
55 #include <sys/lock.h>
56 #include <sys/malloc.h>
57 #include <sys/msan.h>
58 #include <sys/mutex.h>
59 #include <sys/priv.h>
60 #include <sys/proc.h>
61 #include <sys/procdesc.h>
62 #include <sys/ptrace.h>
63 #include <sys/racct.h>
64 #include <sys/resourcevar.h>
65 #include <sys/sched.h>
66 #include <sys/sdt.h>
67 #include <sys/signalvar.h>
68 #include <sys/sx.h>
69 #include <sys/syscall.h>
70 #include <sys/syscallsubr.h>
71 #include <sys/sysent.h>
72 #include <sys/sysproto.h>
73 #include <sys/vmmeter.h>
74 #include <sys/vnode.h>
75 #include <sys/unistd.h>
76
77 #include <security/audit/audit.h>
78 #include <security/mac/mac_framework.h>
79
80 #include <vm/vm.h>
81 #include <vm/pmap.h>
82 #include <vm/vm_map.h>
83 #include <vm/vm_extern.h>
84 #include <vm/uma.h>
85
86 #ifdef KDTRACE_HOOKS
87 #include <sys/dtrace_bsd.h>
88 dtrace_fork_func_t dtrace_fasttrap_fork;
89 #endif
90
91 SDT_PROVIDER_DECLARE(proc);
92 SDT_PROBE_DEFINE3(proc, , , create, "struct proc *", "struct proc *", "int");
93
94 static bool pdfork_implicit_nowaitpid;
95 SYSCTL_BOOL(_kern, OID_AUTO, pdfork_implicit_nowaitpid, CTLFLAG_RWTUN,
96 &pdfork_implicit_nowaitpid, 0,
97 "PD_NOWAITPID is assumed to be always set");
98
99 #ifndef _SYS_SYSPROTO_H_
100 struct fork_args {
101 int dummy;
102 };
103 #endif
104
105 /* ARGSUSED */
106 int
sys_fork(struct thread * td,struct fork_args * uap)107 sys_fork(struct thread *td, struct fork_args *uap)
108 {
109 struct fork_req fr;
110 int error, pid;
111
112 bzero(&fr, sizeof(fr));
113 fr.fr_flags = RFFDG | RFPROC;
114 fr.fr_pidp = &pid;
115 error = fork1(td, &fr);
116 if (error == 0) {
117 td->td_retval[0] = pid;
118 td->td_retval[1] = 0;
119 }
120 return (error);
121 }
122
123 /* ARGUSED */
124 int
sys_pdfork(struct thread * td,struct pdfork_args * uap)125 sys_pdfork(struct thread *td, struct pdfork_args *uap)
126 {
127 struct fork_req fr;
128 struct filecaps fcaps;
129 int error, fd, pid;
130
131 bzero(&fr, sizeof(fr));
132 fr.fr_flags = RFFDG | RFPROC | RFPROCDESC;
133 fr.fr_pidp = &pid;
134 fr.fr_pd_fd = &fd;
135 fr.fr_pd_flags = uap->flags;
136 filecaps_fill(&fcaps);
137 if ((uap->flags & PD_PTRACE_CAP) == 0)
138 cap_rights_clear(&fcaps.fc_rights, CAP_PTRACE);
139 fr.fr_pd_fcaps = &fcaps;
140 AUDIT_ARG_FFLAGS(uap->flags);
141 /*
142 * It is necessary to return fd by reference because 0 is a valid file
143 * descriptor number, and the child needs to be able to distinguish
144 * itself from the parent using the return value.
145 */
146 error = fork1(td, &fr);
147 if (error == 0) {
148 td->td_retval[0] = pid;
149 td->td_retval[1] = 0;
150 error = copyout(&fd, uap->fdp, sizeof(fd));
151 }
152 return (error);
153 }
154
155 /* ARGSUSED */
156 int
sys_vfork(struct thread * td,struct vfork_args * uap)157 sys_vfork(struct thread *td, struct vfork_args *uap)
158 {
159 struct fork_req fr;
160 int error, pid;
161
162 bzero(&fr, sizeof(fr));
163 fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
164 fr.fr_pidp = &pid;
165 error = fork1(td, &fr);
166 if (error == 0) {
167 td->td_retval[0] = pid;
168 td->td_retval[1] = 0;
169 }
170 return (error);
171 }
172
173 int
sys_rfork(struct thread * td,struct rfork_args * uap)174 sys_rfork(struct thread *td, struct rfork_args *uap)
175 {
176 struct fork_req fr;
177 int error, pid;
178
179 /* Don't allow kernel-only flags. */
180 if ((uap->flags & RFKERNELONLY) != 0)
181 return (EXTERROR(EINVAL, "Kernel-only flags %#jx", uap->flags));
182 /* RFSPAWN must not appear with others */
183 if ((uap->flags & RFSPAWN) != 0 && uap->flags != RFSPAWN)
184 return (EXTERROR(EINVAL, "RFSPAWN must be the only flag %#jx",
185 uap->flags));
186
187 AUDIT_ARG_FFLAGS(uap->flags);
188 bzero(&fr, sizeof(fr));
189 if ((uap->flags & RFSPAWN) != 0) {
190 fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
191 fr.fr_flags2 = FR2_DROPSIG_CAUGHT;
192 } else {
193 fr.fr_flags = uap->flags;
194 }
195 fr.fr_pidp = &pid;
196 error = fork1(td, &fr);
197 if (error == 0) {
198 td->td_retval[0] = pid;
199 td->td_retval[1] = 0;
200 }
201 return (error);
202 }
203
204 int
sys_pdrfork(struct thread * td,struct pdrfork_args * uap)205 sys_pdrfork(struct thread *td, struct pdrfork_args *uap)
206 {
207 struct fork_req fr;
208 struct filecaps fcaps;
209 int error, fd, pid;
210
211 bzero(&fr, sizeof(fr));
212 fd = -1;
213
214 AUDIT_ARG_FFLAGS(uap->pdflags);
215 AUDIT_ARG_CMD(uap->rfflags);
216
217 if ((uap->rfflags & (RFSTOPPED | RFHIGHPID)) != 0)
218 return (EXTERROR(EINVAL,
219 "Kernel-only flags %#jx", uap->rfflags));
220
221 /* RFSPAWN must not appear with others */
222 if ((uap->rfflags & RFSPAWN) != 0) {
223 if (uap->rfflags != RFSPAWN)
224 return (EXTERROR(EINVAL,
225 "RFSPAWN must be the only flag %#jx",
226 uap->rfflags));
227 fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPROCDESC;
228 fr.fr_flags2 = FR2_DROPSIG_CAUGHT;
229 } else {
230 if ((uap->rfflags & (RFPROC | RFPROCDESC)) !=
231 (RFPROC | RFPROCDESC)) {
232 return (EXTERROR(EINVAL,
233 "RFPROC|RFPROCDESC required %#jx", uap->rfflags));
234 }
235 fr.fr_flags = uap->rfflags;
236 }
237
238 fr.fr_pidp = &pid;
239 fr.fr_pd_fd = &fd;
240 fr.fr_pd_flags = uap->pdflags;
241 filecaps_fill(&fcaps);
242 if ((uap->pdflags & PD_PTRACE_CAP) == 0)
243 cap_rights_clear(&fcaps.fc_rights, CAP_PTRACE);
244 fr.fr_pd_fcaps = &fcaps;
245 error = fork1(td, &fr);
246 if (error == 0) {
247 td->td_retval[0] = pid;
248 td->td_retval[1] = 0;
249 if ((fr.fr_flags & (RFPROC | RFPROCDESC)) ==
250 (RFPROC | RFPROCDESC) || uap->rfflags == RFSPAWN)
251 error = copyout(&fd, uap->fdp, sizeof(fd));
252 }
253 return (error);
254 }
255
256 int __exclusive_cache_line nprocs = 1; /* process 0 */
257 int lastpid = 0;
258 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
259 "Last used PID");
260
261 /*
262 * Random component to lastpid generation. We mix in a random factor to make
263 * it a little harder to predict. We sanity check the modulus value to avoid
264 * doing it in critical paths. Don't let it be too small or we pointlessly
265 * waste randomness entropy, and don't let it be impossibly large. Using a
266 * modulus that is too big causes a LOT more process table scans and slows
267 * down fork processing as the pidchecked caching is defeated.
268 */
269 static int randompid = 0;
270
271 static int
sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)272 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
273 {
274 int error, pid;
275
276 error = sysctl_wire_old_buffer(req, sizeof(int));
277 if (error != 0)
278 return(error);
279 sx_xlock(&allproc_lock);
280 pid = randompid;
281 error = sysctl_handle_int(oidp, &pid, 0, req);
282 if (error == 0 && req->newptr != NULL) {
283 if (pid == 0)
284 randompid = 0;
285 else if (pid == 1)
286 /* generate a random PID modulus between 100 and 1123 */
287 randompid = 100 + arc4random() % 1024;
288 else if (pid < 0 || pid > pid_max - 100)
289 /* out of range */
290 randompid = pid_max - 100;
291 else if (pid < 100)
292 /* Make it reasonable */
293 randompid = 100;
294 else
295 randompid = pid;
296 }
297 sx_xunlock(&allproc_lock);
298 return (error);
299 }
300
301 SYSCTL_PROC(_kern, OID_AUTO, randompid,
302 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
303 sysctl_kern_randompid, "I",
304 "Random PID modulus. Special values: 0: disable, 1: choose random value");
305
306 extern bitstr_t proc_id_pidmap;
307 extern bitstr_t proc_id_grpidmap;
308 extern bitstr_t proc_id_sessidmap;
309 extern bitstr_t proc_id_reapmap;
310
311 /*
312 * Find an unused process ID
313 *
314 * If RFHIGHPID is set (used during system boot), do not allocate
315 * low-numbered pids.
316 */
317 static int
fork_findpid(int flags)318 fork_findpid(int flags)
319 {
320 pid_t result;
321 int trypid, random;
322
323 /*
324 * Avoid calling arc4random with procid_lock held.
325 */
326 random = 0;
327 if (__predict_false(randompid))
328 random = arc4random() % randompid;
329
330 mtx_lock(&procid_lock);
331
332 trypid = lastpid + 1;
333 if (flags & RFHIGHPID) {
334 if (trypid < 10)
335 trypid = 10;
336 } else {
337 trypid += random;
338 }
339 retry:
340 if (trypid >= pid_max)
341 trypid = 2;
342
343 bit_ffc_at(&proc_id_pidmap, trypid, pid_max, &result);
344 if (result == -1) {
345 KASSERT(trypid != 2, ("unexpectedly ran out of IDs"));
346 trypid = 2;
347 goto retry;
348 }
349 if (bit_test(&proc_id_grpidmap, result) ||
350 bit_test(&proc_id_sessidmap, result) ||
351 bit_test(&proc_id_reapmap, result)) {
352 trypid = result + 1;
353 goto retry;
354 }
355
356 /*
357 * RFHIGHPID does not mess with the lastpid counter during boot.
358 */
359 if ((flags & RFHIGHPID) == 0)
360 lastpid = result;
361
362 bit_set(&proc_id_pidmap, result);
363 mtx_unlock(&procid_lock);
364
365 return (result);
366 }
367
368 static int
fork_norfproc(struct thread * td,int flags)369 fork_norfproc(struct thread *td, int flags)
370 {
371 struct proc *p1;
372 int error;
373
374 KASSERT((flags & RFPROC) == 0,
375 ("fork_norfproc called with RFPROC set"));
376 p1 = td->td_proc;
377
378 /*
379 * Quiesce other threads if necessary. If RFMEM is not specified we
380 * must ensure that other threads do not concurrently create a second
381 * process sharing the vmspace, see vmspace_unshare().
382 */
383 if ((p1->p_flag & (P_HADTHREADS | P_SYSTEM)) == P_HADTHREADS &&
384 ((flags & (RFCFDG | RFFDG)) != 0 || (flags & RFMEM) == 0)) {
385 PROC_LOCK(p1);
386 if (thread_single(p1, SINGLE_BOUNDARY)) {
387 PROC_UNLOCK(p1);
388 return (ERESTART);
389 }
390 PROC_UNLOCK(p1);
391 }
392
393 error = vm_forkproc(td, NULL, NULL, NULL, flags);
394 if (error != 0)
395 goto fail;
396
397 /*
398 * Close all file descriptors.
399 */
400 if ((flags & RFCFDG) != 0) {
401 struct filedesc *fdtmp;
402 struct pwddesc *pdtmp;
403
404 pdtmp = pdinit(td->td_proc->p_pd, false);
405 fdtmp = fdinit();
406 pdescfree(td);
407 fdescfree(td);
408 p1->p_fd = fdtmp;
409 p1->p_pd = pdtmp;
410 }
411
412 /*
413 * Unshare file descriptors (from parent).
414 */
415 if ((flags & RFFDG) != 0) {
416 fdunshare(td);
417 pdunshare(td);
418 }
419
420 fail:
421 if ((p1->p_flag & (P_HADTHREADS | P_SYSTEM)) == P_HADTHREADS &&
422 ((flags & (RFCFDG | RFFDG)) != 0 || (flags & RFMEM) == 0)) {
423 PROC_LOCK(p1);
424 thread_single_end(p1, SINGLE_BOUNDARY);
425 PROC_UNLOCK(p1);
426 }
427 return (error);
428 }
429
430 static void
do_fork(struct thread * td,struct fork_req * fr,struct proc * p2,struct thread * td2,struct vmspace * vm2,struct file * fp_procdesc)431 do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *td2,
432 struct vmspace *vm2, struct file *fp_procdesc)
433 {
434 struct proc *p1, *pptr;
435 struct filedesc *fd;
436 struct filedesc_to_leader *fdtol;
437 struct pwddesc *pd;
438 struct sigacts *newsigacts;
439
440 p1 = td->td_proc;
441
442 PROC_LOCK(p1);
443 bcopy(&p1->p_startcopy, &p2->p_startcopy,
444 __rangeof(struct proc, p_startcopy, p_endcopy));
445 pargs_hold(p2->p_args);
446 PROC_UNLOCK(p1);
447
448 bzero(&p2->p_startzero,
449 __rangeof(struct proc, p_startzero, p_endzero));
450
451 /* Tell the prison that we exist. */
452 prison_proc_hold(p2->p_ucred->cr_prison);
453
454 p2->p_state = PRS_NEW; /* protect against others */
455 p2->p_pid = fork_findpid(fr->fr_flags);
456 AUDIT_ARG_PID(p2->p_pid);
457 TSFORK(p2->p_pid, p1->p_pid);
458
459 sx_xlock(&allproc_lock);
460 LIST_INSERT_HEAD(&allproc, p2, p_list);
461 allproc_gen++;
462 prison_proc_link(p2->p_ucred->cr_prison, p2);
463 sx_xunlock(&allproc_lock);
464
465 sx_xlock(PIDHASHLOCK(p2->p_pid));
466 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
467 sx_xunlock(PIDHASHLOCK(p2->p_pid));
468
469 tidhash_add(td2);
470
471 /*
472 * Malloc things while we don't hold any locks.
473 */
474 if (fr->fr_flags & RFSIGSHARE)
475 newsigacts = NULL;
476 else
477 newsigacts = sigacts_alloc();
478
479 /*
480 * Copy filedesc.
481 */
482 if (fr->fr_flags & RFCFDG) {
483 pd = pdinit(p1->p_pd, false);
484 fd = fdinit();
485 fdtol = NULL;
486 } else if (fr->fr_flags & RFFDG) {
487 if (fr->fr_flags2 & FR2_SHARE_PATHS)
488 pd = pdshare(p1->p_pd);
489 else
490 pd = pdcopy(p1->p_pd);
491 fd = fdcopy(p1->p_fd, p2);
492 fdtol = NULL;
493 } else {
494 if (fr->fr_flags2 & FR2_SHARE_PATHS)
495 pd = pdcopy(p1->p_pd);
496 else
497 pd = pdshare(p1->p_pd);
498 fd = fdshare(p1->p_fd);
499 if (p1->p_fdtol == NULL)
500 p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL,
501 p1->p_leader);
502 if ((fr->fr_flags & RFTHREAD) != 0) {
503 /*
504 * Shared file descriptor table, and shared
505 * process leaders.
506 */
507 fdtol = filedesc_to_leader_share(p1->p_fdtol, p1->p_fd);
508 } else {
509 /*
510 * Shared file descriptor table, and different
511 * process leaders.
512 */
513 fdtol = filedesc_to_leader_alloc(p1->p_fdtol,
514 p1->p_fd, p2);
515 }
516 }
517 /*
518 * Make a proc table entry for the new process.
519 * Start by zeroing the section of proc that is zero-initialized,
520 * then copy the section that is copied directly from the parent.
521 */
522
523 PROC_LOCK(p2);
524 PROC_LOCK(p1);
525
526 bzero(&td2->td_startzero,
527 __rangeof(struct thread, td_startzero, td_endzero));
528
529 bcopy(&td->td_startcopy, &td2->td_startcopy,
530 __rangeof(struct thread, td_startcopy, td_endcopy));
531
532 bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
533 td2->td_sigstk = td->td_sigstk;
534 td2->td_flags = TDF_INMEM;
535 td2->td_lend_user_pri = PRI_MAX;
536
537 #ifdef VIMAGE
538 td2->td_vnet = NULL;
539 td2->td_vnet_lpush = NULL;
540 #endif
541
542 /*
543 * Allow the scheduler to initialize the child.
544 */
545 thread_lock(td);
546 sched_fork(td, td2);
547 /*
548 * Request AST to check for TDP_RFPPWAIT. Do it here
549 * to avoid calling thread_lock() again.
550 */
551 if ((fr->fr_flags & RFPPWAIT) != 0)
552 ast_sched_locked(td, TDA_VFORK);
553 thread_unlock(td);
554
555 /*
556 * Duplicate sub-structures as needed.
557 * Increase reference counts on shared objects.
558 */
559 p2->p_flag = P_INMEM;
560 p2->p_flag2 = p1->p_flag2 & (P2_ASLR_DISABLE | P2_ASLR_ENABLE |
561 P2_ASLR_IGNSTART | P2_NOTRACE | P2_NOTRACE_EXEC |
562 P2_PROTMAX_ENABLE | P2_PROTMAX_DISABLE | P2_TRAPCAP |
563 P2_STKGAP_DISABLE | P2_STKGAP_DISABLE_EXEC | P2_NO_NEW_PRIVS |
564 P2_WXORX_DISABLE | P2_WXORX_ENABLE_EXEC | P2_LOGSIGEXIT_CTL |
565 P2_LOGSIGEXIT_ENABLE);
566 if ((fr->fr_flags & RFPROCDESC) != 0) {
567 p2->p_zombieref = PZOMBIEREF_PROCDESC;
568 if (((fr->fr_pd_flags & PD_NOWAITPID) == 0 &&
569 !pdfork_implicit_nowaitpid) &&
570 (fr->fr_flags & RFNOWAIT) == 0)
571 p2->p_zombieref |= (PZOMBIEREF_PARENT |
572 PZOMBIEREF_NEEDPARENT);
573 } else {
574 p2->p_zombieref = PZOMBIEREF_PARENT | PZOMBIEREF_NEEDPARENT;
575 }
576 p2->p_swtick = ticks;
577 if (p1->p_flag & P_PROFIL)
578 startprofclock(p2);
579
580 if (fr->fr_flags & RFSIGSHARE) {
581 p2->p_sigacts = sigacts_hold(p1->p_sigacts);
582 } else {
583 sigacts_copy(newsigacts, p1->p_sigacts);
584 p2->p_sigacts = newsigacts;
585 if ((fr->fr_flags2 & (FR2_DROPSIG_CAUGHT | FR2_KPROC)) != 0) {
586 mtx_lock(&p2->p_sigacts->ps_mtx);
587 if ((fr->fr_flags2 & FR2_DROPSIG_CAUGHT) != 0)
588 sig_drop_caught(p2);
589 if ((fr->fr_flags2 & FR2_KPROC) != 0)
590 p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
591 mtx_unlock(&p2->p_sigacts->ps_mtx);
592 }
593 }
594
595 if (fr->fr_flags & RFTSIGZMB)
596 p2->p_sigparent = RFTSIGNUM(fr->fr_flags);
597 else if (fr->fr_flags & RFLINUXTHPN)
598 p2->p_sigparent = SIGUSR1;
599 else
600 p2->p_sigparent = SIGCHLD;
601
602 if ((fr->fr_flags2 & FR2_KPROC) != 0) {
603 p2->p_flag |= P_SYSTEM | P_KPROC;
604 td2->td_pflags |= TDP_KTHREAD;
605 }
606
607 p2->p_textvp = p1->p_textvp;
608 p2->p_textdvp = p1->p_textdvp;
609 p2->p_fd = fd;
610 p2->p_fdtol = fdtol;
611 p2->p_pd = pd;
612
613 if (p1->p_flag2 & P2_INHERIT_PROTECTED) {
614 p2->p_flag |= P_PROTECTED;
615 p2->p_flag2 |= P2_INHERIT_PROTECTED;
616 }
617
618 /*
619 * p_limit is copy-on-write. Bump its refcount.
620 */
621 lim_fork(p1, p2);
622
623 thread_cow_get_proc(td2, p2);
624
625 pstats_fork(p1->p_stats, p2->p_stats);
626
627 PROC_UNLOCK(p1);
628 PROC_UNLOCK(p2);
629
630 /*
631 * Bump references to the text vnode and directory, and copy
632 * the hardlink name.
633 */
634 if (p2->p_textvp != NULL)
635 vrefact(p2->p_textvp);
636 if (p2->p_textdvp != NULL)
637 vrefact(p2->p_textdvp);
638 p2->p_binname = p1->p_binname == NULL ? NULL :
639 strdup(p1->p_binname, M_PARGS);
640
641 /*
642 * Set up linkage for kernel based threading.
643 */
644 if ((fr->fr_flags & RFTHREAD) != 0) {
645 mtx_lock(&ppeers_lock);
646 p2->p_peers = p1->p_peers;
647 p1->p_peers = p2;
648 p2->p_leader = p1->p_leader;
649 mtx_unlock(&ppeers_lock);
650 PROC_LOCK(p1->p_leader);
651 if ((p1->p_leader->p_flag & P_WEXIT) != 0) {
652 PROC_UNLOCK(p1->p_leader);
653 /*
654 * The task leader is exiting, so process p1 is
655 * going to be killed shortly. Since p1 obviously
656 * isn't dead yet, we know that the leader is either
657 * sending SIGKILL's to all the processes in this
658 * task or is sleeping waiting for all the peers to
659 * exit. We let p1 complete the fork, but we need
660 * to go ahead and kill the new process p2 since
661 * the task leader may not get a chance to send
662 * SIGKILL to it. We leave it on the list so that
663 * the task leader will wait for this new process
664 * to commit suicide.
665 */
666 PROC_LOCK(p2);
667 kern_psignal(p2, SIGKILL);
668 PROC_UNLOCK(p2);
669 } else
670 PROC_UNLOCK(p1->p_leader);
671 } else {
672 p2->p_peers = NULL;
673 p2->p_leader = p2;
674 }
675
676 sx_xlock(&proctree_lock);
677 PGRP_LOCK(p1->p_pgrp);
678 PROC_LOCK(p2);
679 PROC_LOCK(p1);
680
681 /*
682 * Preserve some more flags in subprocess. P_PROFIL has already
683 * been preserved.
684 */
685 p2->p_flag |= p1->p_flag & P_SUGID;
686 td2->td_pflags |= td->td_pflags & (TDP_ALTSTACK | TDP_SIGFASTBLOCK);
687 td2->td_pflags2 |= td->td_pflags2 & TDP2_UEXTERR;
688 if (p1->p_flag & P_CONTROLT) {
689 SESS_LOCK(p1->p_session);
690 if (p1->p_session->s_ttyvp != NULL)
691 p2->p_flag |= P_CONTROLT;
692 SESS_UNLOCK(p1->p_session);
693 }
694 if (fr->fr_flags & RFPPWAIT)
695 p2->p_flag |= P_PPWAIT;
696
697 p2->p_pgrp = p1->p_pgrp;
698 LIST_INSERT_AFTER(p1, p2, p_pglist);
699 PGRP_UNLOCK(p1->p_pgrp);
700 LIST_INIT(&p2->p_children);
701 LIST_INIT(&p2->p_orphans);
702
703 callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0);
704
705 PROC_UNLOCK(p1);
706
707 /*
708 * Attach the new process to its parent.
709 *
710 * If RFNOWAIT is set, the newly created process becomes a child
711 * of init. This effectively disassociates the child from the
712 * parent.
713 */
714 if ((fr->fr_flags & RFNOWAIT) != 0) {
715 pptr = p1->p_reaper;
716 p2->p_reaper = pptr;
717 } else {
718 p2->p_reaper = (p1->p_treeflag & P_TREE_REAPER) != 0 ?
719 p1 : p1->p_reaper;
720 pptr = p1;
721 }
722 p2->p_pptr = pptr;
723 p2->p_oppid = pptr->p_pid;
724 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
725 LIST_INIT(&p2->p_reaplist);
726 LIST_INSERT_HEAD(&p2->p_reaper->p_reaplist, p2, p_reapsibling);
727 if (p2->p_reaper == p1 && p1 != initproc) {
728 p2->p_reapsubtree = p2->p_pid;
729 proc_id_set_cond(PROC_ID_REAP, p2->p_pid);
730 } else {
731 /*
732 * Explicitly copy this field under the proctree lock, as it
733 * might have changed since the bulk copying of the parent's
734 * fields.
735 */
736 p2->p_reapsubtree = p1->p_reapsubtree;
737 }
738 sx_xunlock(&proctree_lock);
739
740 /* Inform accounting that we have forked. */
741 p2->p_acflag = AFORK;
742 PROC_UNLOCK(p2);
743
744 #ifdef KTRACE
745 ktrprocfork(p1, p2);
746 #endif
747
748 /*
749 * Finish creating the child process. It will return via a different
750 * execution path later. (ie: directly into user mode)
751 */
752 vm_forkproc(td, p2, td2, vm2, fr->fr_flags);
753
754 if (fr->fr_flags == (RFFDG | RFPROC)) {
755 VM_CNT_INC(v_forks);
756 VM_CNT_ADD(v_forkpages, p2->p_vmspace->vm_dsize +
757 p2->p_vmspace->vm_ssize);
758 } else if (fr->fr_flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
759 VM_CNT_INC(v_vforks);
760 VM_CNT_ADD(v_vforkpages, p2->p_vmspace->vm_dsize +
761 p2->p_vmspace->vm_ssize);
762 } else if (p1 == &proc0) {
763 VM_CNT_INC(v_kthreads);
764 VM_CNT_ADD(v_kthreadpages, p2->p_vmspace->vm_dsize +
765 p2->p_vmspace->vm_ssize);
766 } else {
767 VM_CNT_INC(v_rforks);
768 VM_CNT_ADD(v_rforkpages, p2->p_vmspace->vm_dsize +
769 p2->p_vmspace->vm_ssize);
770 }
771
772 /*
773 * Associate the process descriptor with the process before anything
774 * can happen that might cause that process to need the descriptor.
775 * However, don't do this until after fork(2) can no longer fail.
776 */
777 if (fr->fr_flags & RFPROCDESC)
778 procdesc_new(p2, fr->fr_pd_flags);
779
780 /*
781 * Both processes are set up, now check if any loadable modules want
782 * to adjust anything.
783 */
784 EVENTHANDLER_DIRECT_INVOKE(process_fork, p1, p2, fr->fr_flags);
785
786 /*
787 * Set the child start time and mark the process as being complete.
788 */
789 PROC_LOCK(p2);
790 PROC_LOCK(p1);
791 microuptime(&p2->p_stats->p_start);
792 PROC_SLOCK(p2);
793 p2->p_state = PRS_NORMAL;
794 PROC_SUNLOCK(p2);
795
796 #ifdef KDTRACE_HOOKS
797 /*
798 * Tell the DTrace fasttrap provider about the new process so that any
799 * tracepoints inherited from the parent can be removed. We have to do
800 * this only after p_state is PRS_NORMAL since the fasttrap module will
801 * use pfind() later on.
802 */
803 if ((fr->fr_flags & RFMEM) == 0 && dtrace_fasttrap_fork)
804 dtrace_fasttrap_fork(p1, p2);
805 #endif
806 if (fr->fr_flags & RFPPWAIT) {
807 td->td_pflags |= TDP_RFPPWAIT;
808 td->td_rfppwait_p = p2;
809 td->td_dbgflags |= TDB_VFORK;
810 }
811 PROC_UNLOCK(p2);
812
813 /*
814 * Tell any interested parties about the new process.
815 */
816 knote_fork(p1->p_klist, p2->p_pid);
817
818 PROC_UNLOCK(p1);
819 SDT_PROBE3(proc, , , create, p2, p1, fr->fr_flags);
820
821 if (fr->fr_flags & RFPROCDESC) {
822 procdesc_finit(p2->p_procdesc, fp_procdesc);
823 fdrop(fp_procdesc, td);
824 }
825
826 /*
827 * Speculative check for PTRACE_FORK. PTRACE_FORK is not
828 * synced with forks in progress so it is OK if we miss it
829 * if being set atm.
830 */
831 if ((p1->p_ptevents & PTRACE_FORK) != 0) {
832 sx_xlock(&proctree_lock);
833 PROC_LOCK(p2);
834
835 /*
836 * p1->p_ptevents & p1->p_pptr are protected by both
837 * process and proctree locks for modifications,
838 * so owning proctree_lock allows the race-free read.
839 */
840 if ((p1->p_ptevents & PTRACE_FORK) != 0) {
841 /*
842 * Arrange for debugger to receive the fork event.
843 *
844 * We can report PL_FLAG_FORKED regardless of
845 * P_FOLLOWFORK settings, but it does not make a sense
846 * for runaway child.
847 */
848 td->td_dbgflags |= TDB_FORK;
849 td->td_dbg_forked = p2->p_pid;
850 td2->td_dbgflags |= TDB_STOPATFORK;
851 proc_set_traced(p2, true);
852 CTR2(KTR_PTRACE,
853 "do_fork: attaching to new child pid %d: oppid %d",
854 p2->p_pid, p2->p_oppid);
855 proc_reparent(p2, p1->p_pptr, false);
856 }
857 PROC_UNLOCK(p2);
858 sx_xunlock(&proctree_lock);
859 }
860
861 /*
862 * Activate procdesc NOTE_FORK after we attached the debugger
863 * to the child. This guarantees that a debugger which does
864 * kevent() on the process descriptor to get notifications of
865 * fork events, can properly observe the child right after the
866 * notification fired.
867 */
868 procdesc_fork(p1, p2->p_pid);
869
870 racct_proc_fork_done(p2);
871
872 if ((fr->fr_flags & RFSTOPPED) == 0) {
873 if (fr->fr_pidp != NULL)
874 *fr->fr_pidp = p2->p_pid;
875 /*
876 * If RFSTOPPED not requested, make child runnable and
877 * add to run queue.
878 */
879 thread_lock(td2);
880 TD_SET_CAN_RUN(td2);
881 sched_add(td2, SRQ_BORING);
882 } else {
883 *fr->fr_procp = p2;
884 }
885 }
886
887 static void
ast_vfork(struct thread * td,int tda __unused)888 ast_vfork(struct thread *td, int tda __unused)
889 {
890 struct proc *p, *p2;
891
892 MPASS(td->td_pflags & TDP_RFPPWAIT);
893
894 p = td->td_proc;
895 /*
896 * Preserve synchronization semantics of vfork. If
897 * waiting for child to exec or exit, fork set
898 * P_PPWAIT on child, and there we sleep on our proc
899 * (in case of exit).
900 *
901 * Do it after the ptracestop() above is finished, to
902 * not block our debugger until child execs or exits
903 * to finish vfork wait.
904 */
905 td->td_pflags &= ~TDP_RFPPWAIT;
906 p2 = td->td_rfppwait_p;
907 again:
908 PROC_LOCK(p2);
909 while (p2->p_flag & P_PPWAIT) {
910 PROC_LOCK(p);
911 if (thread_suspend_check_needed()) {
912 PROC_UNLOCK(p2);
913 thread_suspend_check(0);
914 PROC_UNLOCK(p);
915 goto again;
916 } else {
917 PROC_UNLOCK(p);
918 }
919 cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
920 }
921 PROC_UNLOCK(p2);
922
923 if (td->td_dbgflags & TDB_VFORK) {
924 PROC_LOCK(p);
925 if (p->p_ptevents & PTRACE_VFORK)
926 ptracestop(td, SIGTRAP, NULL);
927 td->td_dbgflags &= ~TDB_VFORK;
928 PROC_UNLOCK(p);
929 }
930 }
931
932 int
fork1(struct thread * td,struct fork_req * fr)933 fork1(struct thread *td, struct fork_req *fr)
934 {
935 struct proc *p1, *newproc;
936 struct thread *td2;
937 struct vmspace *vm2;
938 struct ucred *cred;
939 struct file *fp_procdesc;
940 struct pgrp *pg;
941 vm_ooffset_t mem_charged;
942 int error, nprocs_new;
943 static int curfail;
944 static struct timeval lastfail;
945 int flags, pages;
946 bool killsx_locked, singlethreaded;
947
948 flags = fr->fr_flags;
949 pages = fr->fr_pages;
950
951 if ((flags & RFSTOPPED) != 0)
952 MPASS(fr->fr_procp != NULL && fr->fr_pidp == NULL);
953 else
954 MPASS(fr->fr_procp == NULL);
955
956 if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0)
957 return (EXTERROR(EINVAL,
958 "Undef or unimplemented flags %#jx", flags));
959
960 if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0)
961 return (EXTERROR(EINVAL,
962 "Signal value requires RFTSIGZMB", flags));
963
964 if ((flags & (RFFDG | RFCFDG)) == (RFFDG | RFCFDG))
965 return (EXTERROR(EINVAL, "Can not copy and clear"));
966
967 if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG)
968 return (EXTERROR(EINVAL, "Invalid signal", RFTSIGNUM(flags)));
969
970 if ((flags & RFPROCDESC) != 0) {
971 if ((flags & RFPROC) == 0)
972 return (EXTERROR(EINVAL,
973 "Can not not create a process yet get a process descriptor"));
974
975 if (fr->fr_pd_fd == NULL)
976 return (EXTERROR(EINVAL,
977 "Must provide a place to put a procdesc if creating one"));
978
979 if ((fr->fr_pd_flags & ~PD_ALLOWED_AT_FORK) != 0)
980 return (EXTERROR(EINVAL,
981 "Invalid pdflags at fork %#jx", fr->fr_pd_flags));
982 }
983
984 p1 = td->td_proc;
985
986 /*
987 * Here we don't create a new process, but we divorce
988 * certain parts of a process from itself.
989 */
990 if ((flags & RFPROC) == 0) {
991 if (fr->fr_procp != NULL)
992 *fr->fr_procp = NULL;
993 else if (fr->fr_pidp != NULL)
994 *fr->fr_pidp = 0;
995 return (fork_norfproc(td, flags));
996 }
997
998 fp_procdesc = NULL;
999 newproc = NULL;
1000 vm2 = NULL;
1001 killsx_locked = false;
1002 singlethreaded = false;
1003
1004 /*
1005 * Increment the nprocs resource before allocations occur.
1006 * Although process entries are dynamically created, we still
1007 * keep a global limit on the maximum number we will
1008 * create. There are hard-limits as to the number of processes
1009 * that can run, established by the KVA and memory usage for
1010 * the process data.
1011 *
1012 * Don't allow a nonprivileged user to use the last ten
1013 * processes; don't let root exceed the limit.
1014 */
1015 nprocs_new = atomic_fetchadd_int(&nprocs, 1) + 1;
1016 if (nprocs_new >= maxproc - 10) {
1017 if (priv_check_cred(td->td_ucred, PRIV_MAXPROC) != 0 ||
1018 nprocs_new >= maxproc) {
1019 error = EAGAIN;
1020 sx_xlock(&allproc_lock);
1021 if (ppsratecheck(&lastfail, &curfail, 1)) {
1022 printf("maxproc limit exceeded by uid %u "
1023 "(pid %d); see tuning(7) and "
1024 "login.conf(5)\n",
1025 td->td_ucred->cr_ruid, p1->p_pid);
1026 }
1027 sx_xunlock(&allproc_lock);
1028 goto fail2;
1029 }
1030 }
1031
1032 /*
1033 * If we are possibly multi-threaded, and there is a process
1034 * sending a signal to our group right now, ensure that our
1035 * other threads cannot be chosen for the signal queueing.
1036 * Otherwise, this might delay signal action, and make the new
1037 * child escape the signaling.
1038 */
1039 pg = p1->p_pgrp;
1040 if (p1->p_numthreads > 1) {
1041 if (sx_try_slock(&pg->pg_killsx) != 0) {
1042 killsx_locked = true;
1043 } else {
1044 PROC_LOCK(p1);
1045 if (thread_single(p1, SINGLE_BOUNDARY)) {
1046 PROC_UNLOCK(p1);
1047 error = ERESTART;
1048 goto fail2;
1049 }
1050 PROC_UNLOCK(p1);
1051 singlethreaded = true;
1052 }
1053 }
1054
1055 /*
1056 * Atomically check for signals and block processes from sending
1057 * a signal to our process group until the child is visible.
1058 */
1059 if (!killsx_locked && sx_slock_sig(&pg->pg_killsx) != 0) {
1060 error = ERESTART;
1061 goto fail2;
1062 }
1063 if (__predict_false(p1->p_pgrp != pg || sig_intr() != 0)) {
1064 /*
1065 * Either the process was moved to other process
1066 * group, or there is pending signal. sx_slock_sig()
1067 * does not check for signals if not sleeping for the
1068 * lock.
1069 */
1070 sx_sunlock(&pg->pg_killsx);
1071 killsx_locked = false;
1072 error = ERESTART;
1073 goto fail2;
1074 } else {
1075 killsx_locked = true;
1076 }
1077
1078 /*
1079 * If required, create a process descriptor in the parent first; we
1080 * will abandon it if something goes wrong. We don't finit() until
1081 * later.
1082 */
1083 if (flags & RFPROCDESC) {
1084 error = procdesc_falloc(td, &fp_procdesc, fr->fr_pd_fd,
1085 fr->fr_pd_flags, fr->fr_pd_fcaps);
1086 if (error != 0)
1087 goto fail2;
1088 fr->fr_pd_fcaps = NULL;
1089 AUDIT_ARG_FD(*fr->fr_pd_fd);
1090 }
1091
1092 mem_charged = 0;
1093 if (pages == 0)
1094 pages = kstack_pages;
1095 /* Allocate new proc. */
1096 newproc = uma_zalloc(proc_zone, M_WAITOK);
1097 PROC_TREE_REF(newproc);
1098 td2 = FIRST_THREAD_IN_PROC(newproc);
1099 if (td2 == NULL) {
1100 td2 = thread_alloc(pages);
1101 if (td2 == NULL) {
1102 error = ENOMEM;
1103 goto fail2;
1104 }
1105 proc_linkup(newproc, td2);
1106 } else {
1107 error = thread_recycle(td2, pages);
1108 if (error != 0)
1109 goto fail2;
1110 }
1111
1112 if ((flags & RFMEM) == 0) {
1113 vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
1114 if (vm2 == NULL) {
1115 error = ENOMEM;
1116 goto fail2;
1117 }
1118 if (!swap_reserve(mem_charged)) {
1119 /*
1120 * The swap reservation failed. The accounting
1121 * from the entries of the copied vm2 will be
1122 * subtracted in vmspace_free(), so force the
1123 * reservation there.
1124 */
1125 swap_reserve_force(mem_charged);
1126 error = ENOMEM;
1127 goto fail2;
1128 }
1129 } else
1130 vm2 = NULL;
1131
1132 /*
1133 * XXX: This is ugly; when we copy resource usage, we need to bump
1134 * per-cred resource counters.
1135 */
1136 newproc->p_ucred = crcowget(td->td_ucred);
1137
1138 /*
1139 * Initialize resource accounting for the child process.
1140 */
1141 error = racct_proc_fork(p1, newproc);
1142 if (error != 0) {
1143 error = EAGAIN;
1144 goto fail1;
1145 }
1146
1147 #ifdef MAC
1148 mac_proc_init(newproc);
1149 #endif
1150
1151 /*
1152 * Increment the count of procs running with this uid. Don't allow
1153 * a nonprivileged user to exceed their current limit.
1154 */
1155 cred = td->td_ucred;
1156 if (!chgproccnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPROC))) {
1157 if (priv_check_cred(cred, PRIV_PROC_LIMIT) != 0)
1158 goto fail0;
1159 chgproccnt(cred->cr_ruidinfo, 1, 0);
1160 }
1161
1162 newproc->p_klist = knlist_alloc(&newproc->p_mtx);
1163
1164 do_fork(td, fr, newproc, td2, vm2, fp_procdesc);
1165 error = 0;
1166 goto cleanup;
1167 fail0:
1168 error = EAGAIN;
1169 #ifdef MAC
1170 mac_proc_destroy(newproc);
1171 #endif
1172 racct_proc_exit(newproc);
1173 fail1:
1174 proc_unset_cred(newproc, false);
1175 fail2:
1176 if (vm2 != NULL)
1177 vmspace_free(vm2);
1178 if (newproc != NULL)
1179 PROC_TREE_UNREF(newproc);
1180 if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) {
1181 fdclose(td, fp_procdesc, *fr->fr_pd_fd);
1182 fdrop(fp_procdesc, td);
1183 }
1184 if (fr->fr_pd_fcaps != NULL)
1185 filecaps_free(fr->fr_pd_fcaps);
1186 atomic_add_int(&nprocs, -1);
1187 cleanup:
1188 if (killsx_locked)
1189 sx_sunlock(&pg->pg_killsx);
1190 if (singlethreaded) {
1191 PROC_LOCK(p1);
1192 thread_single_end(p1, SINGLE_BOUNDARY);
1193 PROC_UNLOCK(p1);
1194 }
1195 if (error != 0)
1196 pause("fork", hz / 2);
1197 return (error);
1198 }
1199
1200 /*
1201 * Handle the return of a child process from fork1(). This function
1202 * is called from the MD fork_trampoline() entry point.
1203 */
1204 void
fork_exit(void (* callout)(void *,struct trapframe *),void * arg,struct trapframe * frame)1205 fork_exit(void (*callout)(void *, struct trapframe *), void *arg,
1206 struct trapframe *frame)
1207 {
1208 struct proc *p;
1209 struct thread *td;
1210 struct thread *dtd;
1211
1212 kmsan_mark(frame, sizeof(*frame), KMSAN_STATE_INITED);
1213
1214 td = curthread;
1215 p = td->td_proc;
1216 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new"));
1217
1218 CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)",
1219 td, td_get_sched(td), p->p_pid, td->td_name);
1220
1221 sched_fork_exit(td);
1222
1223 /*
1224 * Processes normally resume in mi_switch() after being
1225 * cpu_switch()'ed to, but when children start up they arrive here
1226 * instead, so we must do much the same things as mi_switch() would.
1227 */
1228 if ((dtd = PCPU_GET(deadthread))) {
1229 PCPU_SET(deadthread, NULL);
1230 thread_stash(dtd);
1231 }
1232 thread_unlock(td);
1233
1234 /*
1235 * cpu_fork_kthread_handler intercepts this function call to
1236 * have this call a non-return function to stay in kernel mode.
1237 * initproc has its own fork handler, but it does return.
1238 */
1239 KASSERT(callout != NULL, ("NULL callout in fork_exit"));
1240 callout(arg, frame);
1241
1242 /*
1243 * Check if a kernel thread misbehaved and returned from its main
1244 * function.
1245 */
1246 if (p->p_flag & P_KPROC) {
1247 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
1248 td->td_name, p->p_pid);
1249 kthread_exit();
1250 }
1251 mtx_assert(&Giant, MA_NOTOWNED);
1252
1253 /*
1254 * Now going to return to userland.
1255 */
1256
1257 if (p->p_sysent->sv_schedtail != NULL)
1258 (p->p_sysent->sv_schedtail)(td);
1259
1260 userret(td, frame);
1261 }
1262
1263 /*
1264 * Simplified back end of syscall(), used when returning from fork()
1265 * directly into user mode. This function is passed in to fork_exit()
1266 * as the first parameter and is called when returning to a new
1267 * userland process.
1268 */
1269 void
fork_return(struct thread * td,struct trapframe * frame)1270 fork_return(struct thread *td, struct trapframe *frame)
1271 {
1272 struct proc *p;
1273
1274 p = td->td_proc;
1275 if (td->td_dbgflags & TDB_STOPATFORK) {
1276 PROC_LOCK(p);
1277 if ((p->p_flag & P_TRACED) != 0) {
1278 /*
1279 * Inform the debugger if one is still present.
1280 */
1281 td->td_dbgflags |= TDB_CHILD | TDB_SCX | TDB_FSTP;
1282 ptracestop(td, SIGSTOP, NULL);
1283 td->td_dbgflags &= ~(TDB_CHILD | TDB_SCX);
1284 } else {
1285 /*
1286 * ... otherwise clear the request.
1287 */
1288 td->td_dbgflags &= ~TDB_STOPATFORK;
1289 }
1290 PROC_UNLOCK(p);
1291 } else if (p->p_flag & P_TRACED) {
1292 /*
1293 * This is the start of a new thread in a traced
1294 * process. Report a system call exit event.
1295 */
1296 PROC_LOCK(p);
1297 td->td_dbgflags |= TDB_SCX;
1298 if ((p->p_ptevents & PTRACE_SCX) != 0 ||
1299 (td->td_dbgflags & TDB_BORN) != 0)
1300 ptracestop(td, SIGTRAP, NULL);
1301 td->td_dbgflags &= ~(TDB_SCX | TDB_BORN);
1302 PROC_UNLOCK(p);
1303 }
1304
1305 /*
1306 * If the prison was killed mid-fork, die along with it.
1307 */
1308 if (!prison_isalive(td->td_ucred->cr_prison))
1309 kern_exit(td, 0, SIGKILL);
1310
1311 #ifdef KTRACE
1312 if (KTRPOINT(td, KTR_SYSRET))
1313 ktrsysret(td->td_sa.code, 0, 0);
1314 #endif
1315 }
1316
1317 static void
fork_init(void * arg __unused)1318 fork_init(void *arg __unused)
1319 {
1320 ast_register(TDA_VFORK, ASTR_ASTF_REQUIRED | ASTR_TDP, TDP_RFPPWAIT,
1321 ast_vfork);
1322 }
1323 SYSINIT(fork, SI_SUB_INTRINSIC, SI_ORDER_ANY, fork_init, NULL);
1324