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kernel - Fix excessive call stack depth on stuck interrupt
[dragonfly.git] / sys / kern / kern_sig.c
blob294e67a2eebd209cbf9409718f2a4411b525f726
1 /*
2 * Copyright (c) 1982, 1986, 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)kern_sig.c 8.7 (Berkeley) 4/18/94
35 * $FreeBSD: src/sys/kern/kern_sig.c,v 1.72.2.17 2003/05/16 16:34:34 obrien Exp $
36 */
37
38 #include "opt_ktrace.h"
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/kernel.h>
43 #include <sys/sysproto.h>
44 #include <sys/signalvar.h>
45 #include <sys/resourcevar.h>
46 #include <sys/vnode.h>
47 #include <sys/event.h>
48 #include <sys/proc.h>
49 #include <sys/nlookup.h>
50 #include <sys/pioctl.h>
51 #include <sys/acct.h>
52 #include <sys/fcntl.h>
53 #include <sys/lock.h>
54 #include <sys/wait.h>
55 #include <sys/ktrace.h>
56 #include <sys/syslog.h>
57 #include <sys/stat.h>
58 #include <sys/sysent.h>
59 #include <sys/sysctl.h>
60 #include <sys/malloc.h>
61 #include <sys/interrupt.h>
62 #include <sys/unistd.h>
63 #include <sys/kern_syscall.h>
64 #include <sys/vkernel.h>
65
66 #include <sys/signal2.h>
67 #include <sys/thread2.h>
68 #include <sys/spinlock2.h>
69
70 #include <machine/cpu.h>
71 #include <machine/smp.h>
72
73 static int coredump(struct lwp *, int);
74 static char *expand_name(const char *, uid_t, pid_t);
75 static int dokillpg(int sig, int pgid, int all);
76 static int sig_ffs(sigset_t *set);
77 static int sigprop(int sig);
78 static void lwp_signotify(struct lwp *lp);
79 static void lwp_signotify_remote(void *arg);
80 static int kern_sigtimedwait(sigset_t set, siginfo_t *info,
81 struct timespec *timeout);
82 static void proc_stopwait(struct proc *p);
83
84 static int filt_sigattach(struct knote *kn);
85 static void filt_sigdetach(struct knote *kn);
86 static int filt_signal(struct knote *kn, long hint);
87
88 struct filterops sig_filtops =
89 { FILTEROP_MPSAFE, filt_sigattach, filt_sigdetach, filt_signal };
90
91 static int kern_logsigexit = 1;
92 SYSCTL_INT(_kern, KERN_LOGSIGEXIT, logsigexit, CTLFLAG_RW,
93 &kern_logsigexit, 0,
94 "Log processes quitting on abnormal signals to syslog(3)");
95
96 /*
97 * Can process p, with pcred pc, send the signal sig to process q?
98 */
99 #define CANSIGNAL(q, sig) \
100 (!p_trespass(curproc->p_ucred, (q)->p_ucred) || \
101 ((sig) == SIGCONT && (q)->p_session == curproc->p_session))
102
103 /*
104 * Policy -- Can real uid ruid with ucred uc send a signal to process q?
105 */
106 #define CANSIGIO(ruid, uc, q) \
107 ((uc)->cr_uid == 0 || \
108 (ruid) == (q)->p_ucred->cr_ruid || \
109 (uc)->cr_uid == (q)->p_ucred->cr_ruid || \
110 (ruid) == (q)->p_ucred->cr_uid || \
111 (uc)->cr_uid == (q)->p_ucred->cr_uid)
112
113 int sugid_coredump;
114 SYSCTL_INT(_kern, OID_AUTO, sugid_coredump, CTLFLAG_RW,
115 &sugid_coredump, 0, "Enable coredumping set user/group ID processes");
116
117 static int do_coredump = 1;
118 SYSCTL_INT(_kern, OID_AUTO, coredump, CTLFLAG_RW,
119 &do_coredump, 0, "Enable/Disable coredumps");
120
121 /*
122 * Signal properties and actions.
123 * The array below categorizes the signals and their default actions
124 * according to the following properties:
125 */
126 #define SA_KILL 0x01 /* terminates process by default */
127 #define SA_CORE 0x02 /* ditto and coredumps */
128 #define SA_STOP 0x04 /* suspend process */
129 #define SA_TTYSTOP 0x08 /* ditto, from tty */
130 #define SA_IGNORE 0x10 /* ignore by default */
131 #define SA_CONT 0x20 /* continue if suspended */
132 #define SA_CANTMASK 0x40 /* non-maskable, catchable */
133 #define SA_CKPT 0x80 /* checkpoint process */
134
135
136 static int sigproptbl[NSIG] = {
137 SA_KILL, /* SIGHUP */
138 SA_KILL, /* SIGINT */
139 SA_KILL|SA_CORE, /* SIGQUIT */
140 SA_KILL|SA_CORE, /* SIGILL */
141 SA_KILL|SA_CORE, /* SIGTRAP */
142 SA_KILL|SA_CORE, /* SIGABRT */
143 SA_KILL|SA_CORE, /* SIGEMT */
144 SA_KILL|SA_CORE, /* SIGFPE */
145 SA_KILL, /* SIGKILL */
146 SA_KILL|SA_CORE, /* SIGBUS */
147 SA_KILL|SA_CORE, /* SIGSEGV */
148 SA_KILL|SA_CORE, /* SIGSYS */
149 SA_KILL, /* SIGPIPE */
150 SA_KILL, /* SIGALRM */
151 SA_KILL, /* SIGTERM */
152 SA_IGNORE, /* SIGURG */
153 SA_STOP, /* SIGSTOP */
154 SA_STOP|SA_TTYSTOP, /* SIGTSTP */
155 SA_IGNORE|SA_CONT, /* SIGCONT */
156 SA_IGNORE, /* SIGCHLD */
157 SA_STOP|SA_TTYSTOP, /* SIGTTIN */
158 SA_STOP|SA_TTYSTOP, /* SIGTTOU */
159 SA_IGNORE, /* SIGIO */
160 SA_KILL, /* SIGXCPU */
161 SA_KILL, /* SIGXFSZ */
162 SA_KILL, /* SIGVTALRM */
163 SA_KILL, /* SIGPROF */
164 SA_IGNORE, /* SIGWINCH */
165 SA_IGNORE, /* SIGINFO */
166 SA_KILL, /* SIGUSR1 */
167 SA_KILL, /* SIGUSR2 */
168 SA_IGNORE, /* SIGTHR */
169 SA_CKPT, /* SIGCKPT */
170 SA_KILL|SA_CKPT, /* SIGCKPTEXIT */
171 SA_IGNORE,
172 SA_IGNORE,
173 SA_IGNORE,
174 SA_IGNORE,
175 SA_IGNORE,
176 SA_IGNORE,
177 SA_IGNORE,
178 SA_IGNORE,
179 SA_IGNORE,
180 SA_IGNORE,
181 SA_IGNORE,
182 SA_IGNORE,
183 SA_IGNORE,
184 SA_IGNORE,
185 SA_IGNORE,
186 SA_IGNORE,
187 SA_IGNORE,
188 SA_IGNORE,
189 SA_IGNORE,
190 SA_IGNORE,
191 SA_IGNORE,
192 SA_IGNORE,
193 SA_IGNORE,
194 SA_IGNORE,
195 SA_IGNORE,
196 SA_IGNORE,
197 SA_IGNORE,
198 SA_IGNORE,
199 SA_IGNORE,
200 SA_IGNORE,
201
202 };
203
204 static __inline int
205 sigprop(int sig)
206 {
207
208 if (sig > 0 && sig < NSIG)
209 return (sigproptbl[_SIG_IDX(sig)]);
210 return (0);
211 }
212
213 static __inline int
214 sig_ffs(sigset_t *set)
215 {
216 int i;
217
218 for (i = 0; i < _SIG_WORDS; i++)
219 if (set->__bits[i])
220 return (ffs(set->__bits[i]) + (i * 32));
221 return (0);
222 }
223
224 /*
225 * No requirements.
226 */
227 int
228 kern_sigaction(int sig, struct sigaction *act, struct sigaction *oact)
229 {
230 struct thread *td = curthread;
231 struct proc *p = td->td_proc;
232 struct lwp *lp;
233 struct sigacts *ps = p->p_sigacts;
234
235 if (sig <= 0 || sig > _SIG_MAXSIG)
236 return (EINVAL);
237
238 lwkt_gettoken(&p->p_token);
239
240 if (oact) {
241 oact->sa_handler = ps->ps_sigact[_SIG_IDX(sig)];
242 oact->sa_mask = ps->ps_catchmask[_SIG_IDX(sig)];
243 oact->sa_flags = 0;
244 if (SIGISMEMBER(ps->ps_sigonstack, sig))
245 oact->sa_flags |= SA_ONSTACK;
246 if (!SIGISMEMBER(ps->ps_sigintr, sig))
247 oact->sa_flags |= SA_RESTART;
248 if (SIGISMEMBER(ps->ps_sigreset, sig))
249 oact->sa_flags |= SA_RESETHAND;
250 if (SIGISMEMBER(ps->ps_signodefer, sig))
251 oact->sa_flags |= SA_NODEFER;
252 if (SIGISMEMBER(ps->ps_siginfo, sig))
253 oact->sa_flags |= SA_SIGINFO;
254 if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDSTOP)
255 oact->sa_flags |= SA_NOCLDSTOP;
256 if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDWAIT)
257 oact->sa_flags |= SA_NOCLDWAIT;
258 }
259 if (act) {
260 /*
261 * Check for invalid requests. KILL and STOP cannot be
262 * caught.
263 */
264 if (sig == SIGKILL || sig == SIGSTOP) {
265 if (act->sa_handler != SIG_DFL) {
266 lwkt_reltoken(&p->p_token);
267 return (EINVAL);
268 }
269 }
270
271 /*
272 * Change setting atomically.
273 */
274 ps->ps_catchmask[_SIG_IDX(sig)] = act->sa_mask;
275 SIG_CANTMASK(ps->ps_catchmask[_SIG_IDX(sig)]);
276 if (act->sa_flags & SA_SIGINFO) {
277 ps->ps_sigact[_SIG_IDX(sig)] =
278 (__sighandler_t *)act->sa_sigaction;
279 SIGADDSET(ps->ps_siginfo, sig);
280 } else {
281 ps->ps_sigact[_SIG_IDX(sig)] = act->sa_handler;
282 SIGDELSET(ps->ps_siginfo, sig);
283 }
284 if (!(act->sa_flags & SA_RESTART))
285 SIGADDSET(ps->ps_sigintr, sig);
286 else
287 SIGDELSET(ps->ps_sigintr, sig);
288 if (act->sa_flags & SA_ONSTACK)
289 SIGADDSET(ps->ps_sigonstack, sig);
290 else
291 SIGDELSET(ps->ps_sigonstack, sig);
292 if (act->sa_flags & SA_RESETHAND)
293 SIGADDSET(ps->ps_sigreset, sig);
294 else
295 SIGDELSET(ps->ps_sigreset, sig);
296 if (act->sa_flags & SA_NODEFER)
297 SIGADDSET(ps->ps_signodefer, sig);
298 else
299 SIGDELSET(ps->ps_signodefer, sig);
300 if (sig == SIGCHLD) {
301 if (act->sa_flags & SA_NOCLDSTOP)
302 p->p_sigacts->ps_flag |= PS_NOCLDSTOP;
303 else
304 p->p_sigacts->ps_flag &= ~PS_NOCLDSTOP;
305 if (act->sa_flags & SA_NOCLDWAIT) {
306 /*
307 * Paranoia: since SA_NOCLDWAIT is implemented
308 * by reparenting the dying child to PID 1 (and
309 * trust it to reap the zombie), PID 1 itself
310 * is forbidden to set SA_NOCLDWAIT.
311 */
312 if (p->p_pid == 1)
313 p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
314 else
315 p->p_sigacts->ps_flag |= PS_NOCLDWAIT;
316 } else {
317 p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
318 }
319 if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
320 ps->ps_flag |= PS_CLDSIGIGN;
321 else
322 ps->ps_flag &= ~PS_CLDSIGIGN;
323 }
324 /*
325 * Set bit in p_sigignore for signals that are set to SIG_IGN,
326 * and for signals set to SIG_DFL where the default is to
327 * ignore. However, don't put SIGCONT in p_sigignore, as we
328 * have to restart the process.
329 *
330 * Also remove the signal from the process and lwp signal
331 * list.
332 */
333 if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN ||
334 (sigprop(sig) & SA_IGNORE &&
335 ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)) {
336 SIGDELSET_ATOMIC(p->p_siglist, sig);
337 FOREACH_LWP_IN_PROC(lp, p) {
338 spin_lock(&lp->lwp_spin);
339 SIGDELSET(lp->lwp_siglist, sig);
340 spin_unlock(&lp->lwp_spin);
341 }
342 if (sig != SIGCONT) {
343 /* easier in ksignal */
344 SIGADDSET(p->p_sigignore, sig);
345 }
346 SIGDELSET(p->p_sigcatch, sig);
347 } else {
348 SIGDELSET(p->p_sigignore, sig);
349 if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)
350 SIGDELSET(p->p_sigcatch, sig);
351 else
352 SIGADDSET(p->p_sigcatch, sig);
353 }
354 }
355 lwkt_reltoken(&p->p_token);
356 return (0);
357 }
358
359 int
360 sys_sigaction(struct sigaction_args *uap)
361 {
362 struct sigaction act, oact;
363 struct sigaction *actp, *oactp;
364 int error;
365
366 actp = (uap->act != NULL) ? &act : NULL;
367 oactp = (uap->oact != NULL) ? &oact : NULL;
368 if (actp) {
369 error = copyin(uap->act, actp, sizeof(act));
370 if (error)
371 return (error);
372 }
373 error = kern_sigaction(uap->sig, actp, oactp);
374 if (oactp && !error) {
375 error = copyout(oactp, uap->oact, sizeof(oact));
376 }
377 return (error);
378 }
379
380 /*
381 * Initialize signal state for process 0;
382 * set to ignore signals that are ignored by default.
383 */
384 void
385 siginit(struct proc *p)
386 {
387 int i;
388
389 for (i = 1; i <= NSIG; i++)
390 if (sigprop(i) & SA_IGNORE && i != SIGCONT)
391 SIGADDSET(p->p_sigignore, i);
392 }
393
394 /*
395 * Reset signals for an exec of the specified process.
396 */
397 void
398 execsigs(struct proc *p)
399 {
400 struct sigacts *ps = p->p_sigacts;
401 struct lwp *lp;
402 int sig;
403
404 lp = ONLY_LWP_IN_PROC(p);
405
406 /*
407 * Reset caught signals. Held signals remain held
408 * through p_sigmask (unless they were caught,
409 * and are now ignored by default).
410 */
411 while (SIGNOTEMPTY(p->p_sigcatch)) {
412 sig = sig_ffs(&p->p_sigcatch);
413 SIGDELSET(p->p_sigcatch, sig);
414 if (sigprop(sig) & SA_IGNORE) {
415 if (sig != SIGCONT)
416 SIGADDSET(p->p_sigignore, sig);
417 SIGDELSET_ATOMIC(p->p_siglist, sig);
418 /* don't need spinlock */
419 SIGDELSET(lp->lwp_siglist, sig);
420 }
421 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
422 }
423
424 /*
425 * Reset stack state to the user stack.
426 * Clear set of signals caught on the signal stack.
427 */
428 lp->lwp_sigstk.ss_flags = SS_DISABLE;
429 lp->lwp_sigstk.ss_size = 0;
430 lp->lwp_sigstk.ss_sp = NULL;
431 lp->lwp_flags &= ~LWP_ALTSTACK;
432 /*
433 * Reset no zombies if child dies flag as Solaris does.
434 */
435 p->p_sigacts->ps_flag &= ~(PS_NOCLDWAIT | PS_CLDSIGIGN);
436 if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
437 ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL;
438 }
439
440 /*
441 * kern_sigprocmask() - MP SAFE ONLY IF p == curproc
442 *
443 * Manipulate signal mask. This routine is MP SAFE *ONLY* if
444 * p == curproc.
445 */
446 int
447 kern_sigprocmask(int how, sigset_t *set, sigset_t *oset)
448 {
449 struct thread *td = curthread;
450 struct lwp *lp = td->td_lwp;
451 struct proc *p = td->td_proc;
452 int error;
453
454 lwkt_gettoken(&p->p_token);
455
456 if (oset != NULL)
457 *oset = lp->lwp_sigmask;
458
459 error = 0;
460 if (set != NULL) {
461 switch (how) {
462 case SIG_BLOCK:
463 SIG_CANTMASK(*set);
464 SIGSETOR(lp->lwp_sigmask, *set);
465 break;
466 case SIG_UNBLOCK:
467 SIGSETNAND(lp->lwp_sigmask, *set);
468 break;
469 case SIG_SETMASK:
470 SIG_CANTMASK(*set);
471 lp->lwp_sigmask = *set;
472 break;
473 default:
474 error = EINVAL;
475 break;
476 }
477 }
478
479 lwkt_reltoken(&p->p_token);
480
481 return (error);
482 }
483
484 /*
485 * sigprocmask()
486 *
487 * MPSAFE
488 */
489 int
490 sys_sigprocmask(struct sigprocmask_args *uap)
491 {
492 sigset_t set, oset;
493 sigset_t *setp, *osetp;
494 int error;
495
496 setp = (uap->set != NULL) ? &set : NULL;
497 osetp = (uap->oset != NULL) ? &oset : NULL;
498 if (setp) {
499 error = copyin(uap->set, setp, sizeof(set));
500 if (error)
501 return (error);
502 }
503 error = kern_sigprocmask(uap->how, setp, osetp);
504 if (osetp && !error) {
505 error = copyout(osetp, uap->oset, sizeof(oset));
506 }
507 return (error);
508 }
509
510 /*
511 * MPSAFE
512 */
513 int
514 kern_sigpending(struct __sigset *set)
515 {
516 struct lwp *lp = curthread->td_lwp;
517
518 *set = lwp_sigpend(lp);
519
520 return (0);
521 }
522
523 /*
524 * MPSAFE
525 */
526 int
527 sys_sigpending(struct sigpending_args *uap)
528 {
529 sigset_t set;
530 int error;
531
532 error = kern_sigpending(&set);
533
534 if (error == 0)
535 error = copyout(&set, uap->set, sizeof(set));
536 return (error);
537 }
538
539 /*
540 * Suspend process until signal, providing mask to be set
541 * in the meantime.
542 *
543 * MPSAFE
544 */
545 int
546 kern_sigsuspend(struct __sigset *set)
547 {
548 struct thread *td = curthread;
549 struct lwp *lp = td->td_lwp;
550 struct proc *p = td->td_proc;
551 struct sigacts *ps = p->p_sigacts;
552
553 /*
554 * When returning from sigsuspend, we want
555 * the old mask to be restored after the
556 * signal handler has finished. Thus, we
557 * save it here and mark the sigacts structure
558 * to indicate this.
559 */
560 lp->lwp_oldsigmask = lp->lwp_sigmask;
561 lp->lwp_flags |= LWP_OLDMASK;
562
563 SIG_CANTMASK(*set);
564 lp->lwp_sigmask = *set;
565 while (tsleep(ps, PCATCH, "pause", 0) == 0)
566 /* void */;
567 /* always return EINTR rather than ERESTART... */
568 return (EINTR);
569 }
570
571 /*
572 * Note nonstandard calling convention: libc stub passes mask, not
573 * pointer, to save a copyin.
574 *
575 * MPSAFE
576 */
577 int
578 sys_sigsuspend(struct sigsuspend_args *uap)
579 {
580 sigset_t mask;
581 int error;
582
583 error = copyin(uap->sigmask, &mask, sizeof(mask));
584 if (error)
585 return (error);
586
587 error = kern_sigsuspend(&mask);
588
589 return (error);
590 }
591
592 /*
593 * MPSAFE
594 */
595 int
596 kern_sigaltstack(struct sigaltstack *ss, struct sigaltstack *oss)
597 {
598 struct thread *td = curthread;
599 struct lwp *lp = td->td_lwp;
600 struct proc *p = td->td_proc;
601
602 if ((lp->lwp_flags & LWP_ALTSTACK) == 0)
603 lp->lwp_sigstk.ss_flags |= SS_DISABLE;
604
605 if (oss)
606 *oss = lp->lwp_sigstk;
607
608 if (ss) {
609 if (ss->ss_flags & ~SS_DISABLE)
610 return (EINVAL);
611 if (ss->ss_flags & SS_DISABLE) {
612 if (lp->lwp_sigstk.ss_flags & SS_ONSTACK)
613 return (EPERM);
614 lp->lwp_flags &= ~LWP_ALTSTACK;
615 lp->lwp_sigstk.ss_flags = ss->ss_flags;
616 } else {
617 if (ss->ss_size < p->p_sysent->sv_minsigstksz)
618 return (ENOMEM);
619 lp->lwp_flags |= LWP_ALTSTACK;
620 lp->lwp_sigstk = *ss;
621 }
622 }
623
624 return (0);
625 }
626
627 /*
628 * MPSAFE
629 */
630 int
631 sys_sigaltstack(struct sigaltstack_args *uap)
632 {
633 stack_t ss, oss;
634 int error;
635
636 if (uap->ss) {
637 error = copyin(uap->ss, &ss, sizeof(ss));
638 if (error)
639 return (error);
640 }
641
642 error = kern_sigaltstack(uap->ss ? &ss : NULL, uap->oss ? &oss : NULL);
643
644 if (error == 0 && uap->oss)
645 error = copyout(&oss, uap->oss, sizeof(*uap->oss));
646 return (error);
647 }
648
649 /*
650 * Common code for kill process group/broadcast kill.
651 * cp is calling process.
652 */
653 struct killpg_info {
654 int nfound;
655 int sig;
656 };
657
658 static int killpg_all_callback(struct proc *p, void *data);
659
660 static int
661 dokillpg(int sig, int pgid, int all)
662 {
663 struct killpg_info info;
664 struct proc *cp = curproc;
665 struct proc *p;
666 struct pgrp *pgrp;
667
668 info.nfound = 0;
669 info.sig = sig;
670
671 if (all) {
672 /*
673 * broadcast
674 */
675 allproc_scan(killpg_all_callback, &info);
676 } else {
677 if (pgid == 0) {
678 /*
679 * zero pgid means send to my process group.
680 */
681 pgrp = cp->p_pgrp;
682 pgref(pgrp);
683 } else {
684 pgrp = pgfind(pgid);
685 if (pgrp == NULL)
686 return (ESRCH);
687 }
688
689 /*
690 * Must interlock all signals against fork
691 */
692 lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
693 LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
694 if (p->p_pid <= 1 ||
695 p->p_stat == SZOMB ||
696 (p->p_flags & P_SYSTEM) ||
697 !CANSIGNAL(p, sig)) {
698 continue;
699 }
700 ++info.nfound;
701 if (sig)
702 ksignal(p, sig);
703 }
704 lockmgr(&pgrp->pg_lock, LK_RELEASE);
705 pgrel(pgrp);
706 }
707 return (info.nfound ? 0 : ESRCH);
708 }
709
710 static int
711 killpg_all_callback(struct proc *p, void *data)
712 {
713 struct killpg_info *info = data;
714
715 if (p->p_pid <= 1 || (p->p_flags & P_SYSTEM) ||
716 p == curproc || !CANSIGNAL(p, info->sig)) {
717 return (0);
718 }
719 ++info->nfound;
720 if (info->sig)
721 ksignal(p, info->sig);
722 return(0);
723 }
724
725 /*
726 * Send a general signal to a process or LWPs within that process.
727 *
728 * Note that new signals cannot be sent if a process is exiting or already
729 * a zombie, but we return success anyway as userland is likely to not handle
730 * the race properly.
731 *
732 * No requirements.
733 */
734 int
735 kern_kill(int sig, pid_t pid, lwpid_t tid)
736 {
737 int t;
738
739 if ((u_int)sig > _SIG_MAXSIG)
740 return (EINVAL);
741
742 if (pid > 0) {
743 struct proc *p;
744 struct lwp *lp = NULL;
745
746 /*
747 * Send a signal to a single process. If the kill() is
748 * racing an exiting process which has not yet been reaped
749 * act as though the signal was delivered successfully but
750 * don't actually try to deliver the signal.
751 */
752 if ((p = pfind(pid)) == NULL) {
753 if ((p = zpfind(pid)) == NULL)
754 return (ESRCH);
755 PRELE(p);
756 return (0);
757 }
758 if (p != curproc) {
759 lwkt_gettoken_shared(&p->p_token);
760 if (!CANSIGNAL(p, sig)) {
761 lwkt_reltoken(&p->p_token);
762 PRELE(p);
763 return (EPERM);
764 }
765 lwkt_reltoken(&p->p_token);
766 }
767
768 /*
769 * NOP if the process is exiting. Note that lwpsignal() is
770 * called directly with P_WEXIT set to kill individual LWPs
771 * during exit, which is allowed.
772 */
773 if (p->p_flags & P_WEXIT) {
774 PRELE(p);
775 return (0);
776 }
777 if (tid != -1) {
778 lwkt_gettoken_shared(&p->p_token);
779 lp = lwp_rb_tree_RB_LOOKUP(&p->p_lwp_tree, tid);
780 if (lp == NULL) {
781 lwkt_reltoken(&p->p_token);
782 PRELE(p);
783 return (ESRCH);
784 }
785 LWPHOLD(lp);
786 lwkt_reltoken(&p->p_token);
787 }
788 if (sig)
789 lwpsignal(p, lp, sig);
790 if (lp)
791 LWPRELE(lp);
792 PRELE(p);
793
794 return (0);
795 }
796
797 /*
798 * If we come here, pid is a special broadcast pid.
799 * This doesn't mix with a tid.
800 */
801 if (tid != -1)
802 return (EINVAL);
803
804 switch (pid) {
805 case -1: /* broadcast signal */
806 t = (dokillpg(sig, 0, 1));
807 break;
808 case 0: /* signal own process group */
809 t = (dokillpg(sig, 0, 0));
810 break;
811 default: /* negative explicit process group */
812 t = (dokillpg(sig, -pid, 0));
813 break;
814 }
815 return t;
816 }
817
818 int
819 sys_kill(struct kill_args *uap)
820 {
821 int error;
822
823 error = kern_kill(uap->signum, uap->pid, -1);
824 return (error);
825 }
826
827 int
828 sys_lwp_kill(struct lwp_kill_args *uap)
829 {
830 int error;
831 pid_t pid = uap->pid;
832
833 /*
834 * A tid is mandatory for lwp_kill(), otherwise
835 * you could simply use kill().
836 */
837 if (uap->tid == -1)
838 return (EINVAL);
839
840 /*
841 * To save on a getpid() function call for intra-process
842 * signals, pid == -1 means current process.
843 */
844 if (pid == -1)
845 pid = curproc->p_pid;
846
847 error = kern_kill(uap->signum, pid, uap->tid);
848 return (error);
849 }
850
851 /*
852 * Send a signal to a process group.
853 */
854 void
855 gsignal(int pgid, int sig)
856 {
857 struct pgrp *pgrp;
858
859 if (pgid && (pgrp = pgfind(pgid)))
860 pgsignal(pgrp, sig, 0);
861 }
862
863 /*
864 * Send a signal to a process group. If checktty is 1,
865 * limit to members which have a controlling terminal.
866 *
867 * pg_lock interlocks against a fork that might be in progress, to
868 * ensure that the new child process picks up the signal.
869 */
870 void
871 pgsignal(struct pgrp *pgrp, int sig, int checkctty)
872 {
873 struct proc *p;
874
875 /*
876 * Must interlock all signals against fork
877 */
878 if (pgrp) {
879 pgref(pgrp);
880 lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
881 LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
882 if (checkctty == 0 || p->p_flags & P_CONTROLT)
883 ksignal(p, sig);
884 }
885 lockmgr(&pgrp->pg_lock, LK_RELEASE);
886 pgrel(pgrp);
887 }
888 }
889
890 /*
891 * Send a signal caused by a trap to the current lwp. If it will be caught
892 * immediately, deliver it with correct code. Otherwise, post it normally.
893 *
894 * These signals may ONLY be delivered to the specified lwp and may never
895 * be delivered to the process generically.
896 */
897 void
898 trapsignal(struct lwp *lp, int sig, u_long code)
899 {
900 struct proc *p = lp->lwp_proc;
901 struct sigacts *ps = p->p_sigacts;
902
903 /*
904 * If we are a virtual kernel running an emulated user process
905 * context, switch back to the virtual kernel context before
906 * trying to post the signal.
907 */
908 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
909 struct trapframe *tf = lp->lwp_md.md_regs;
910 tf->tf_trapno = 0;
911 vkernel_trap(lp, tf);
912 }
913
914 if ((p->p_flags & P_TRACED) == 0 && SIGISMEMBER(p->p_sigcatch, sig) &&
915 !SIGISMEMBER(lp->lwp_sigmask, sig)) {
916 lp->lwp_ru.ru_nsignals++;
917 #ifdef KTRACE
918 if (KTRPOINT(lp->lwp_thread, KTR_PSIG))
919 ktrpsig(lp, sig, ps->ps_sigact[_SIG_IDX(sig)],
920 &lp->lwp_sigmask, code);
921 #endif
922 (*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)], sig,
923 &lp->lwp_sigmask, code);
924 SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
925 if (!SIGISMEMBER(ps->ps_signodefer, sig))
926 SIGADDSET(lp->lwp_sigmask, sig);
927 if (SIGISMEMBER(ps->ps_sigreset, sig)) {
928 /*
929 * See kern_sigaction() for origin of this code.
930 */
931 SIGDELSET(p->p_sigcatch, sig);
932 if (sig != SIGCONT &&
933 sigprop(sig) & SA_IGNORE)
934 SIGADDSET(p->p_sigignore, sig);
935 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
936 }
937 } else {
938 lp->lwp_code = code; /* XXX for core dump/debugger */
939 lp->lwp_sig = sig; /* XXX to verify code */
940 lwpsignal(p, lp, sig);
941 }
942 }
943
944 /*
945 * Find a suitable lwp to deliver the signal to. Returns NULL if all
946 * lwps hold the signal blocked.
947 *
948 * Caller must hold p->p_token.
949 *
950 * Returns a lp or NULL. If non-NULL the lp is held and its token is
951 * acquired.
952 */
953 static struct lwp *
954 find_lwp_for_signal(struct proc *p, int sig)
955 {
956 struct lwp *lp;
957 struct lwp *run, *sleep, *stop;
958
959 /*
960 * If the running/preempted thread belongs to the proc to which
961 * the signal is being delivered and this thread does not block
962 * the signal, then we can avoid a context switch by delivering
963 * the signal to this thread, because it will return to userland
964 * soon anyways.
965 */
966 lp = lwkt_preempted_proc();
967 if (lp != NULL && lp->lwp_proc == p) {
968 LWPHOLD(lp);
969 lwkt_gettoken(&lp->lwp_token);
970 if (!SIGISMEMBER(lp->lwp_sigmask, sig)) {
971 /* return w/ token held */
972 return (lp);
973 }
974 lwkt_reltoken(&lp->lwp_token);
975 LWPRELE(lp);
976 }
977
978 run = sleep = stop = NULL;
979 FOREACH_LWP_IN_PROC(lp, p) {
980 /*
981 * If the signal is being blocked by the lwp, then this
982 * lwp is not eligible for receiving the signal.
983 */
984 LWPHOLD(lp);
985 lwkt_gettoken(&lp->lwp_token);
986
987 if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
988 lwkt_reltoken(&lp->lwp_token);
989 LWPRELE(lp);
990 continue;
991 }
992
993 switch (lp->lwp_stat) {
994 case LSRUN:
995 if (sleep) {
996 lwkt_token_swap();
997 lwkt_reltoken(&sleep->lwp_token);
998 LWPRELE(sleep);
999 sleep = NULL;
1000 run = lp;
1001 } else if (stop) {
1002 lwkt_token_swap();
1003 lwkt_reltoken(&stop->lwp_token);
1004 LWPRELE(stop);
1005 stop = NULL;
1006 run = lp;
1007 } else {
1008 run = lp;
1009 }
1010 break;
1011 case LSSLEEP:
1012 if (lp->lwp_flags & LWP_SINTR) {
1013 if (sleep) {
1014 lwkt_reltoken(&lp->lwp_token);
1015 LWPRELE(lp);
1016 } else if (stop) {
1017 lwkt_token_swap();
1018 lwkt_reltoken(&stop->lwp_token);
1019 LWPRELE(stop);
1020 stop = NULL;
1021 sleep = lp;
1022 } else {
1023 sleep = lp;
1024 }
1025 } else {
1026 lwkt_reltoken(&lp->lwp_token);
1027 LWPRELE(lp);
1028 }
1029 break;
1030 case LSSTOP:
1031 if (sleep) {
1032 lwkt_reltoken(&lp->lwp_token);
1033 LWPRELE(lp);
1034 } else if (stop) {
1035 lwkt_reltoken(&lp->lwp_token);
1036 LWPRELE(lp);
1037 } else {
1038 stop = lp;
1039 }
1040 break;
1041 }
1042 if (run)
1043 break;
1044 }
1045
1046 if (run != NULL)
1047 return (run);
1048 else if (sleep != NULL)
1049 return (sleep);
1050 else
1051 return (stop);
1052 }
1053
1054 /*
1055 * Send the signal to the process. If the signal has an action, the action
1056 * is usually performed by the target process rather than the caller; we add
1057 * the signal to the set of pending signals for the process.
1058 *
1059 * Exceptions:
1060 * o When a stop signal is sent to a sleeping process that takes the
1061 * default action, the process is stopped without awakening it.
1062 * o SIGCONT restarts stopped processes (or puts them back to sleep)
1063 * regardless of the signal action (eg, blocked or ignored).
1064 *
1065 * Other ignored signals are discarded immediately.
1066 *
1067 * If the caller wishes to call this function from a hard code section the
1068 * caller must already hold p->p_token (see kern_clock.c).
1069 *
1070 * No requirements.
1071 */
1072 void
1073 ksignal(struct proc *p, int sig)
1074 {
1075 lwpsignal(p, NULL, sig);
1076 }
1077
1078 /*
1079 * The core for ksignal. lp may be NULL, then a suitable thread
1080 * will be chosen. If not, lp MUST be a member of p.
1081 *
1082 * If the caller wishes to call this function from a hard code section the
1083 * caller must already hold p->p_token.
1084 *
1085 * No requirements.
1086 */
1087 void
1088 lwpsignal(struct proc *p, struct lwp *lp, int sig)
1089 {
1090 struct proc *q;
1091 sig_t action;
1092 int prop;
1093
1094 if (sig > _SIG_MAXSIG || sig <= 0) {
1095 kprintf("lwpsignal: signal %d\n", sig);
1096 panic("lwpsignal signal number");
1097 }
1098
1099 KKASSERT(lp == NULL || lp->lwp_proc == p);
1100
1101 /*
1102 * We don't want to race... well, all sorts of things. Get appropriate
1103 * tokens.
1104 *
1105 * Don't try to deliver a generic signal to an exiting process,
1106 * the signal structures could be in flux. We check the LWP later
1107 * on.
1108 */
1109 PHOLD(p);
1110 if (lp) {
1111 LWPHOLD(lp);
1112 lwkt_gettoken(&lp->lwp_token);
1113 } else {
1114 lwkt_gettoken(&p->p_token);
1115 if (p->p_flags & P_WEXIT)
1116 goto out;
1117 }
1118
1119 prop = sigprop(sig);
1120
1121 /*
1122 * If proc is traced, always give parent a chance;
1123 * if signal event is tracked by procfs, give *that*
1124 * a chance, as well.
1125 */
1126 if ((p->p_flags & P_TRACED) || (p->p_stops & S_SIG)) {
1127 action = SIG_DFL;
1128 } else {
1129 /*
1130 * Do not try to deliver signals to an exiting lwp other
1131 * than SIGKILL. Note that we must still deliver the signal
1132 * if P_WEXIT is set in the process flags.
1133 */
1134 if (lp && (lp->lwp_mpflags & LWP_MP_WEXIT) && sig != SIGKILL) {
1135 lwkt_reltoken(&lp->lwp_token);
1136 LWPRELE(lp);
1137 PRELE(p);
1138 return;
1139 }
1140
1141 /*
1142 * If the signal is being ignored, then we forget about
1143 * it immediately. NOTE: We don't set SIGCONT in p_sigignore,
1144 * and if it is set to SIG_IGN, action will be SIG_DFL here.
1145 */
1146 if (SIGISMEMBER(p->p_sigignore, sig)) {
1147 /*
1148 * Even if a signal is set SIG_IGN, it may still be
1149 * lurking in a kqueue.
1150 */
1151 KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
1152 if (lp) {
1153 lwkt_reltoken(&lp->lwp_token);
1154 LWPRELE(lp);
1155 } else {
1156 lwkt_reltoken(&p->p_token);
1157 }
1158 PRELE(p);
1159 return;
1160 }
1161 if (SIGISMEMBER(p->p_sigcatch, sig))
1162 action = SIG_CATCH;
1163 else
1164 action = SIG_DFL;
1165 }
1166
1167 /*
1168 * If continuing, clear any pending STOP signals for the whole
1169 * process.
1170 */
1171 if (prop & SA_CONT) {
1172 lwkt_gettoken(&p->p_token);
1173 SIG_STOPSIGMASK_ATOMIC(p->p_siglist);
1174 lwkt_reltoken(&p->p_token);
1175 }
1176
1177 if (prop & SA_STOP) {
1178 /*
1179 * If sending a tty stop signal to a member of an orphaned
1180 * process group, discard the signal here if the action
1181 * is default; don't stop the process below if sleeping,
1182 * and don't clear any pending SIGCONT.
1183 */
1184 if ((prop & SA_TTYSTOP) && p->p_pgrp->pg_jobc == 0 &&
1185 action == SIG_DFL) {
1186 if (lp) {
1187 lwkt_reltoken(&lp->lwp_token);
1188 LWPRELE(lp);
1189 } else {
1190 lwkt_reltoken(&p->p_token);
1191 }
1192 PRELE(p);
1193 return;
1194 }
1195 lwkt_gettoken(&p->p_token);
1196 SIG_CONTSIGMASK_ATOMIC(p->p_siglist);
1197 p->p_flags &= ~P_CONTINUED;
1198 lwkt_reltoken(&p->p_token);
1199 }
1200
1201 if (p->p_stat == SSTOP) {
1202 /*
1203 * Nobody can handle this signal, add it to the lwp or
1204 * process pending list
1205 */
1206 lwkt_gettoken(&p->p_token);
1207 if (p->p_stat != SSTOP) {
1208 lwkt_reltoken(&p->p_token);
1209 goto not_stopped;
1210 }
1211 if (lp) {
1212 spin_lock(&lp->lwp_spin);
1213 SIGADDSET(lp->lwp_siglist, sig);
1214 spin_unlock(&lp->lwp_spin);
1215 } else {
1216 SIGADDSET_ATOMIC(p->p_siglist, sig);
1217 }
1218
1219 /*
1220 * If the process is stopped and is being traced, then no
1221 * further action is necessary.
1222 */
1223 if (p->p_flags & P_TRACED) {
1224 lwkt_reltoken(&p->p_token);
1225 goto out;
1226 }
1227
1228 /*
1229 * If the process is stopped and receives a KILL signal,
1230 * make the process runnable.
1231 */
1232 if (sig == SIGKILL) {
1233 proc_unstop(p, SSTOP);
1234 lwkt_reltoken(&p->p_token);
1235 goto active_process;
1236 }
1237
1238 /*
1239 * If the process is stopped and receives a CONT signal,
1240 * then try to make the process runnable again.
1241 */
1242 if (prop & SA_CONT) {
1243 /*
1244 * If SIGCONT is default (or ignored), we continue the
1245 * process but don't leave the signal in p_siglist, as
1246 * it has no further action. If SIGCONT is held, we
1247 * continue the process and leave the signal in
1248 * p_siglist. If the process catches SIGCONT, let it
1249 * handle the signal itself.
1250 *
1251 * XXX what if the signal is being held blocked?
1252 *
1253 * Token required to interlock kern_wait().
1254 * Reparenting can also cause a race so we have to
1255 * hold (q).
1256 */
1257 q = p->p_pptr;
1258 PHOLD(q);
1259 lwkt_gettoken(&q->p_token);
1260 p->p_flags |= P_CONTINUED;
1261 wakeup(q);
1262 if (action == SIG_DFL)
1263 SIGDELSET_ATOMIC(p->p_siglist, sig);
1264 proc_unstop(p, SSTOP);
1265 lwkt_reltoken(&q->p_token);
1266 PRELE(q);
1267 lwkt_reltoken(&p->p_token);
1268 if (action == SIG_CATCH)
1269 goto active_process;
1270 goto out;
1271 }
1272
1273 /*
1274 * If the process is stopped and receives another STOP
1275 * signal, we do not need to stop it again. If we did
1276 * the shell could get confused.
1277 *
1278 * However, if the current/preempted lwp is part of the
1279 * process receiving the signal, we need to keep it,
1280 * so that this lwp can stop in issignal() later, as
1281 * we don't want to wait until it reaches userret!
1282 */
1283 if (prop & SA_STOP) {
1284 if (lwkt_preempted_proc() == NULL ||
1285 lwkt_preempted_proc()->lwp_proc != p) {
1286 SIGDELSET_ATOMIC(p->p_siglist, sig);
1287 }
1288 }
1289
1290 /*
1291 * Otherwise the process is stopped and it received some
1292 * signal, which does not change its stopped state. When
1293 * the process is continued a wakeup(p) will be issued which
1294 * will wakeup any threads sleeping in tstop().
1295 */
1296 lwkt_reltoken(&p->p_token);
1297 goto out;
1298 /* NOTREACHED */
1299 }
1300 not_stopped:
1301 ;
1302 /* else not stopped */
1303 active_process:
1304
1305 /*
1306 * Never deliver a lwp-specific signal to a random lwp.
1307 */
1308 if (lp == NULL) {
1309 /* NOTE: returns lp w/ token held */
1310 lp = find_lwp_for_signal(p, sig);
1311 if (lp) {
1312 if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
1313 lwkt_reltoken(&lp->lwp_token);
1314 LWPRELE(lp);
1315 lp = NULL;
1316 /* maintain proc token */
1317 } else {
1318 lwkt_token_swap();
1319 lwkt_reltoken(&p->p_token);
1320 /* maintain lp token */
1321 }
1322 }
1323 }
1324
1325 /*
1326 * Deliver to the process generically if (1) the signal is being
1327 * sent to any thread or (2) we could not find a thread to deliver
1328 * it to.
1329 */
1330 if (lp == NULL) {
1331 KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
1332 SIGADDSET_ATOMIC(p->p_siglist, sig);
1333 goto out;
1334 }
1335
1336 /*
1337 * Deliver to a specific LWP whether it masks it or not. It will
1338 * not be dispatched if masked but we must still deliver it.
1339 */
1340 if (p->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) &&
1341 (p->p_flags & P_TRACED) == 0) {
1342 lwkt_gettoken(&p->p_token);
1343 p->p_nice = NZERO;
1344 lwkt_reltoken(&p->p_token);
1345 }
1346
1347 /*
1348 * If the process receives a STOP signal which indeed needs to
1349 * stop the process, do so. If the process chose to catch the
1350 * signal, it will be treated like any other signal.
1351 */
1352 if ((prop & SA_STOP) && action == SIG_DFL) {
1353 /*
1354 * If a child holding parent blocked, stopping
1355 * could cause deadlock. Take no action at this
1356 * time.
1357 */
1358 lwkt_gettoken(&p->p_token);
1359 if (p->p_flags & P_PPWAIT) {
1360 SIGADDSET_ATOMIC(p->p_siglist, sig);
1361 lwkt_reltoken(&p->p_token);
1362 goto out;
1363 }
1364
1365 /*
1366 * Do not actually try to manipulate the process, but simply
1367 * stop it. Lwps will stop as soon as they safely can.
1368 *
1369 * Ignore stop if the process is exiting.
1370 */
1371 if ((p->p_flags & P_WEXIT) == 0) {
1372 p->p_xstat = sig;
1373 proc_stop(p, SSTOP);
1374 }
1375 lwkt_reltoken(&p->p_token);
1376 goto out;
1377 }
1378
1379 /*
1380 * If it is a CONT signal with default action, just ignore it.
1381 */
1382 if ((prop & SA_CONT) && action == SIG_DFL)
1383 goto out;
1384
1385 /*
1386 * Mark signal pending at this specific thread.
1387 */
1388 spin_lock(&lp->lwp_spin);
1389 SIGADDSET(lp->lwp_siglist, sig);
1390 spin_unlock(&lp->lwp_spin);
1391
1392 lwp_signotify(lp);
1393
1394 out:
1395 if (lp) {
1396 lwkt_reltoken(&lp->lwp_token);
1397 LWPRELE(lp);
1398 } else {
1399 lwkt_reltoken(&p->p_token);
1400 }
1401 PRELE(p);
1402 }
1403
1404 /*
1405 * Notify the LWP that a signal has arrived. The LWP does not have to be
1406 * sleeping on the current cpu.
1407 *
1408 * p->p_token and lp->lwp_token must be held on call.
1409 *
1410 * We can only safely schedule the thread on its current cpu and only if
1411 * one of the SINTR flags is set. If an SINTR flag is set AND we are on
1412 * the correct cpu we are properly interlocked, otherwise we could be
1413 * racing other thread transition states (or the lwp is on the user scheduler
1414 * runq but not scheduled) and must not do anything.
1415 *
1416 * Since we hold the lwp token we know the lwp cannot be ripped out from
1417 * under us so we can safely hold it to prevent it from being ripped out
1418 * from under us if we are forced to IPI another cpu to make the local
1419 * checks there.
1420 *
1421 * Adjustment of lp->lwp_stat can only occur when we hold the lwp_token,
1422 * which we won't in an IPI so any fixups have to be done here, effectively
1423 * replicating part of what setrunnable() does.
1424 */
1425 static void
1426 lwp_signotify(struct lwp *lp)
1427 {
1428 thread_t dtd;
1429
1430 ASSERT_LWKT_TOKEN_HELD(&lp->lwp_token);
1431 dtd = lp->lwp_thread;
1432
1433 crit_enter();
1434 if (lp == lwkt_preempted_proc()) {
1435 /*
1436 * lwp is on the current cpu AND it is currently running
1437 * (we preempted it).
1438 */
1439 signotify();
1440 } else if (lp->lwp_flags & LWP_SINTR) {
1441 /*
1442 * lwp is sitting in tsleep() with PCATCH set
1443 */
1444 if (dtd->td_gd == mycpu) {
1445 setrunnable(lp);
1446 } else {
1447 /*
1448 * We can only adjust lwp_stat while we hold the
1449 * lwp_token, and we won't in the IPI function.
1450 */
1451 LWPHOLD(lp);
1452 if (lp->lwp_stat == LSSTOP)
1453 lp->lwp_stat = LSSLEEP;
1454 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
1455 }
1456 } else if (dtd->td_flags & TDF_SINTR) {
1457 /*
1458 * lwp is sitting in lwkt_sleep() with PCATCH set.
1459 */
1460 if (dtd->td_gd == mycpu) {
1461 setrunnable(lp);
1462 } else {
1463 /*
1464 * We can only adjust lwp_stat while we hold the
1465 * lwp_token, and we won't in the IPI function.
1466 */
1467 LWPHOLD(lp);
1468 if (lp->lwp_stat == LSSTOP)
1469 lp->lwp_stat = LSSLEEP;
1470 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
1471 }
1472 } else {
1473 /*
1474 * Otherwise the lwp is either in some uninterruptible state
1475 * or it is on the userland scheduler's runqueue waiting to
1476 * be scheduled to a cpu, or it is running in userland. We
1477 * generally want to send an IPI so a running target gets the
1478 * signal ASAP, otherwise a scheduler-tick worth of latency
1479 * will occur.
1480 *
1481 * Issue an IPI to the remote cpu to knock it into the kernel,
1482 * remote cpu will issue the cpu-local signotify() if the IPI
1483 * preempts the desired thread.
1484 */
1485 if (dtd->td_gd != mycpu) {
1486 LWPHOLD(lp);
1487 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
1488 }
1489 }
1490 crit_exit();
1491 }
1492
1493 /*
1494 * This function is called via an IPI so we cannot call setrunnable() here
1495 * (because while we hold the lp we don't own its token, and can't get it
1496 * from an IPI).
1497 *
1498 * We are interlocked by virtue of being on the same cpu as the target. If
1499 * we still are and LWP_SINTR or TDF_SINTR is set we can safely schedule
1500 * the target thread.
1501 */
1502 static void
1503 lwp_signotify_remote(void *arg)
1504 {
1505 struct lwp *lp = arg;
1506 thread_t td = lp->lwp_thread;
1507
1508 if (lp == lwkt_preempted_proc()) {
1509 signotify();
1510 LWPRELE(lp);
1511 } else if (td->td_gd == mycpu) {
1512 if ((lp->lwp_flags & LWP_SINTR) ||
1513 (td->td_flags & TDF_SINTR)) {
1514 lwkt_schedule(td);
1515 }
1516 LWPRELE(lp);
1517 } else {
1518 lwkt_send_ipiq(td->td_gd, lwp_signotify_remote, lp);
1519 /* LWPHOLD() is forwarded to the target cpu */
1520 }
1521 }
1522
1523 /*
1524 * Caller must hold p->p_token
1525 */
1526 void
1527 proc_stop(struct proc *p, int sig)
1528 {
1529 struct proc *q;
1530 struct lwp *lp;
1531
1532 ASSERT_LWKT_TOKEN_HELD(&p->p_token);
1533
1534 /*
1535 * If somebody raced us, be happy with it. SCORE overrides SSTOP.
1536 */
1537 if (sig == SCORE) {
1538 if (p->p_stat == SCORE || p->p_stat == SZOMB)
1539 return;
1540 } else {
1541 if (p->p_stat == SSTOP || p->p_stat == SCORE ||
1542 p->p_stat == SZOMB) {
1543 return;
1544 }
1545 }
1546 p->p_stat = sig;
1547
1548 FOREACH_LWP_IN_PROC(lp, p) {
1549 LWPHOLD(lp);
1550 lwkt_gettoken(&lp->lwp_token);
1551
1552 switch (lp->lwp_stat) {
1553 case LSSTOP:
1554 /*
1555 * Do nothing, we are already counted in
1556 * p_nstopped.
1557 */
1558 break;
1559
1560 case LSSLEEP:
1561 /*
1562 * We're sleeping, but we will stop before
1563 * returning to userspace, so count us
1564 * as stopped as well. We set LWP_MP_WSTOP
1565 * to signal the lwp that it should not
1566 * increase p_nstopped when reaching tstop().
1567 *
1568 * LWP_MP_WSTOP is protected by lp->lwp_token.
1569 */
1570 if ((lp->lwp_mpflags & LWP_MP_WSTOP) == 0) {
1571 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WSTOP);
1572 ++p->p_nstopped;
1573 }
1574 break;
1575
1576 case LSRUN:
1577 /*
1578 * We might notify ourself, but that's not
1579 * a problem.
1580 */
1581 lwp_signotify(lp);
1582 break;
1583 }
1584 lwkt_reltoken(&lp->lwp_token);
1585 LWPRELE(lp);
1586 }
1587
1588 if (p->p_nstopped == p->p_nthreads) {
1589 /*
1590 * Token required to interlock kern_wait(). Reparenting can
1591 * also cause a race so we have to hold (q).
1592 */
1593 q = p->p_pptr;
1594 PHOLD(q);
1595 lwkt_gettoken(&q->p_token);
1596 p->p_flags &= ~P_WAITED;
1597 wakeup(q);
1598 if ((q->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0)
1599 ksignal(p->p_pptr, SIGCHLD);
1600 lwkt_reltoken(&q->p_token);
1601 PRELE(q);
1602 }
1603 }
1604
1605 /*
1606 * Caller must hold p_token
1607 */
1608 void
1609 proc_unstop(struct proc *p, int sig)
1610 {
1611 struct lwp *lp;
1612
1613 ASSERT_LWKT_TOKEN_HELD(&p->p_token);
1614
1615 if (p->p_stat != sig)
1616 return;
1617
1618 p->p_stat = SACTIVE;
1619
1620 FOREACH_LWP_IN_PROC(lp, p) {
1621 LWPHOLD(lp);
1622 lwkt_gettoken(&lp->lwp_token);
1623
1624 switch (lp->lwp_stat) {
1625 case LSRUN:
1626 /*
1627 * Uh? Not stopped? Well, I guess that's okay.
1628 */
1629 if (bootverbose)
1630 kprintf("proc_unstop: lwp %d/%d not sleeping\n",
1631 p->p_pid, lp->lwp_tid);
1632 break;
1633
1634 case LSSLEEP:
1635 /*
1636 * Still sleeping. Don't bother waking it up.
1637 * However, if this thread was counted as
1638 * stopped, undo this.
1639 *
1640 * Nevertheless we call setrunnable() so that it
1641 * will wake up in case a signal or timeout arrived
1642 * in the meantime.
1643 *
1644 * LWP_MP_WSTOP is protected by lp->lwp_token.
1645 */
1646 if (lp->lwp_mpflags & LWP_MP_WSTOP) {
1647 atomic_clear_int(&lp->lwp_mpflags,
1648 LWP_MP_WSTOP);
1649 --p->p_nstopped;
1650 } else {
1651 if (bootverbose)
1652 kprintf("proc_unstop: lwp %d/%d sleeping, not stopped\n",
1653 p->p_pid, lp->lwp_tid);
1654 }
1655 /* FALLTHROUGH */
1656
1657 case LSSTOP:
1658 /*
1659 * This handles any lwp's waiting in a tsleep with
1660 * SIGCATCH.
1661 */
1662 lwp_signotify(lp);
1663 break;
1664
1665 }
1666 lwkt_reltoken(&lp->lwp_token);
1667 LWPRELE(lp);
1668 }
1669
1670 /*
1671 * This handles any lwp's waiting in tstop(). We have interlocked
1672 * the setting of p_stat by acquiring and releasing each lpw's
1673 * token.
1674 */
1675 wakeup(p);
1676 }
1677
1678 /*
1679 * Wait for all threads except the current thread to stop.
1680 */
1681 static void
1682 proc_stopwait(struct proc *p)
1683 {
1684 while ((p->p_stat == SSTOP || p->p_stat == SCORE) &&
1685 p->p_nstopped < p->p_nthreads - 1) {
1686 tsleep_interlock(&p->p_nstopped, 0);
1687 if (p->p_nstopped < p->p_nthreads - 1) {
1688 tsleep(&p->p_nstopped, PINTERLOCKED, "stopwt", hz);
1689 }
1690 }
1691 }
1692
1693 /*
1694 * No requirements.
1695 */
1696 static int
1697 kern_sigtimedwait(sigset_t waitset, siginfo_t *info, struct timespec *timeout)
1698 {
1699 sigset_t savedmask, set;
1700 struct proc *p = curproc;
1701 struct lwp *lp = curthread->td_lwp;
1702 int error, sig, hz, timevalid = 0;
1703 struct timespec rts, ets, ts;
1704 struct timeval tv;
1705
1706 error = 0;
1707 sig = 0;
1708 ets.tv_sec = 0; /* silence compiler warning */
1709 ets.tv_nsec = 0; /* silence compiler warning */
1710 SIG_CANTMASK(waitset);
1711 savedmask = lp->lwp_sigmask;
1712
1713 if (timeout) {
1714 if (timeout->tv_sec >= 0 && timeout->tv_nsec >= 0 &&
1715 timeout->tv_nsec < 1000000000) {
1716 timevalid = 1;
1717 getnanouptime(&rts);
1718 ets = rts;
1719 timespecadd(&ets, timeout);
1720 }
1721 }
1722
1723 for (;;) {
1724 set = lwp_sigpend(lp);
1725 SIGSETAND(set, waitset);
1726 if ((sig = sig_ffs(&set)) != 0) {
1727 SIGFILLSET(lp->lwp_sigmask);
1728 SIGDELSET(lp->lwp_sigmask, sig);
1729 SIG_CANTMASK(lp->lwp_sigmask);
1730 sig = issignal(lp, 1, 0);
1731 /*
1732 * It may be a STOP signal, in the case, issignal
1733 * returns 0, because we may stop there, and new
1734 * signal can come in, we should restart if we got
1735 * nothing.
1736 */
1737 if (sig == 0)
1738 continue;
1739 else
1740 break;
1741 }
1742
1743 /*
1744 * Previous checking got nothing, and we retried but still
1745 * got nothing, we should return the error status.
1746 */
1747 if (error)
1748 break;
1749
1750 /*
1751 * POSIX says this must be checked after looking for pending
1752 * signals.
1753 */
1754 if (timeout) {
1755 if (timevalid == 0) {
1756 error = EINVAL;
1757 break;
1758 }
1759 getnanouptime(&rts);
1760 if (timespeccmp(&rts, &ets, >=)) {
1761 error = EAGAIN;
1762 break;
1763 }
1764 ts = ets;
1765 timespecsub(&ts, &rts);
1766 TIMESPEC_TO_TIMEVAL(&tv, &ts);
1767 hz = tvtohz_high(&tv);
1768 } else {
1769 hz = 0;
1770 }
1771
1772 lp->lwp_sigmask = savedmask;
1773 SIGSETNAND(lp->lwp_sigmask, waitset);
1774 /*
1775 * We won't ever be woken up. Instead, our sleep will
1776 * be broken in lwpsignal().
1777 */
1778 error = tsleep(&p->p_sigacts, PCATCH, "sigwt", hz);
1779 if (timeout) {
1780 if (error == ERESTART) {
1781 /* can not restart a timeout wait. */
1782 error = EINTR;
1783 } else if (error == EAGAIN) {
1784 /* will calculate timeout by ourself. */
1785 error = 0;
1786 }
1787 }
1788 /* Retry ... */
1789 }
1790
1791 lp->lwp_sigmask = savedmask;
1792 if (sig) {
1793 error = 0;
1794 bzero(info, sizeof(*info));
1795 info->si_signo = sig;
1796 spin_lock(&lp->lwp_spin);
1797 lwp_delsig(lp, sig, 1); /* take the signal! */
1798 spin_unlock(&lp->lwp_spin);
1799
1800 if (sig == SIGKILL) {
1801 sigexit(lp, sig);
1802 /* NOT REACHED */
1803 }
1804 }
1805
1806 return (error);
1807 }
1808
1809 /*
1810 * MPALMOSTSAFE
1811 */
1812 int
1813 sys_sigtimedwait(struct sigtimedwait_args *uap)
1814 {
1815 struct timespec ts;
1816 struct timespec *timeout;
1817 sigset_t set;
1818 siginfo_t info;
1819 int error;
1820
1821 if (uap->timeout) {
1822 error = copyin(uap->timeout, &ts, sizeof(ts));
1823 if (error)
1824 return (error);
1825 timeout = &ts;
1826 } else {
1827 timeout = NULL;
1828 }
1829 error = copyin(uap->set, &set, sizeof(set));
1830 if (error)
1831 return (error);
1832 error = kern_sigtimedwait(set, &info, timeout);
1833 if (error)
1834 return (error);
1835 if (uap->info)
1836 error = copyout(&info, uap->info, sizeof(info));
1837 /* Repost if we got an error. */
1838 /*
1839 * XXX lwp
1840 *
1841 * This could transform a thread-specific signal to another
1842 * thread / process pending signal.
1843 */
1844 if (error) {
1845 ksignal(curproc, info.si_signo);
1846 } else {
1847 uap->sysmsg_result = info.si_signo;
1848 }
1849 return (error);
1850 }
1851
1852 /*
1853 * MPALMOSTSAFE
1854 */
1855 int
1856 sys_sigwaitinfo(struct sigwaitinfo_args *uap)
1857 {
1858 siginfo_t info;
1859 sigset_t set;
1860 int error;
1861
1862 error = copyin(uap->set, &set, sizeof(set));
1863 if (error)
1864 return (error);
1865 error = kern_sigtimedwait(set, &info, NULL);
1866 if (error)
1867 return (error);
1868 if (uap->info)
1869 error = copyout(&info, uap->info, sizeof(info));
1870 /* Repost if we got an error. */
1871 /*
1872 * XXX lwp
1873 *
1874 * This could transform a thread-specific signal to another
1875 * thread / process pending signal.
1876 */
1877 if (error) {
1878 ksignal(curproc, info.si_signo);
1879 } else {
1880 uap->sysmsg_result = info.si_signo;
1881 }
1882 return (error);
1883 }
1884
1885 /*
1886 * If the current process has received a signal that would interrupt a
1887 * system call, return EINTR or ERESTART as appropriate.
1888 */
1889 int
1890 iscaught(struct lwp *lp)
1891 {
1892 struct proc *p = lp->lwp_proc;
1893 int sig;
1894
1895 if (p) {
1896 if ((sig = CURSIG(lp)) != 0) {
1897 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
1898 return (EINTR);
1899 return (ERESTART);
1900 }
1901 }
1902 return(EWOULDBLOCK);
1903 }
1904
1905 /*
1906 * If the current lwp/proc has received a signal (should be caught or cause
1907 * termination, should interrupt current syscall), return the signal number.
1908 * Stop signals with default action are processed immediately, then cleared;
1909 * they aren't returned. This is checked after each entry to the system for
1910 * a syscall or trap (though this can usually be done without calling issignal
1911 * by checking the pending signal masks in the CURSIG macro).
1912 *
1913 * This routine is called via CURSIG/__cursig. We will acquire and release
1914 * p->p_token but if the caller needs to interlock the test the caller must
1915 * also hold p->p_token.
1916 *
1917 * while (sig = CURSIG(curproc))
1918 * postsig(sig);
1919 */
1920 int
1921 issignal(struct lwp *lp, int maytrace, int *ptokp)
1922 {
1923 struct proc *p = lp->lwp_proc;
1924 sigset_t mask;
1925 int sig, prop;
1926 int haveptok;
1927
1928 for (;;) {
1929 int traced = (p->p_flags & P_TRACED) || (p->p_stops & S_SIG);
1930
1931 haveptok = 0;
1932
1933 /*
1934 * If this process is supposed to stop, stop this thread.
1935 */
1936 if (STOPLWP(p, lp)) {
1937 lwkt_gettoken(&p->p_token);
1938 tstop();
1939 lwkt_reltoken(&p->p_token);
1940 }
1941
1942 /*
1943 * Quick check without token
1944 */
1945 mask = lwp_sigpend(lp);
1946 SIGSETNAND(mask, lp->lwp_sigmask);
1947 if (p->p_flags & P_PPWAIT)
1948 SIG_STOPSIGMASK(mask);
1949 if (SIGISEMPTY(mask)) /* no signal to send */
1950 return (0);
1951
1952 /*
1953 * If the signal is a member of the process signal set
1954 * we need p_token (even if it is also a member of the
1955 * lwp signal set).
1956 */
1957 sig = sig_ffs(&mask);
1958 if (SIGISMEMBER(p->p_siglist, sig)) {
1959 /*
1960 * Recheck with token
1961 */
1962 haveptok = 1;
1963 lwkt_gettoken(&p->p_token);
1964
1965 mask = lwp_sigpend(lp);
1966 SIGSETNAND(mask, lp->lwp_sigmask);
1967 if (p->p_flags & P_PPWAIT)
1968 SIG_STOPSIGMASK(mask);
1969 if (SIGISEMPTY(mask)) { /* no signal to send */
1970 /* haveptok is TRUE */
1971 lwkt_reltoken(&p->p_token);
1972 return (0);
1973 }
1974 sig = sig_ffs(&mask);
1975 }
1976
1977 STOPEVENT(p, S_SIG, sig);
1978
1979 /*
1980 * We should see pending but ignored signals
1981 * only if P_TRACED was on when they were posted.
1982 */
1983 if (SIGISMEMBER(p->p_sigignore, sig) && (traced == 0)) {
1984 spin_lock(&lp->lwp_spin);
1985 lwp_delsig(lp, sig, haveptok);
1986 spin_unlock(&lp->lwp_spin);
1987 if (haveptok)
1988 lwkt_reltoken(&p->p_token);
1989 continue;
1990 }
1991 if (maytrace &&
1992 (p->p_flags & P_TRACED) &&
1993 (p->p_flags & P_PPWAIT) == 0) {
1994 /*
1995 * If traced, always stop, and stay stopped until
1996 * released by the parent.
1997 *
1998 * NOTE: SSTOP may get cleared during the loop,
1999 * but we do not re-notify the parent if we have
2000 * to loop several times waiting for the parent
2001 * to let us continue.
2002 *
2003 * XXX not sure if this is still true
2004 */
2005 if (haveptok == 0) {
2006 lwkt_gettoken(&p->p_token);
2007 haveptok = 1;
2008 }
2009 p->p_xstat = sig;
2010 proc_stop(p, SSTOP);
2011 do {
2012 tstop();
2013 } while (!trace_req(p) && (p->p_flags & P_TRACED));
2014
2015 /*
2016 * If parent wants us to take the signal,
2017 * then it will leave it in p->p_xstat;
2018 * otherwise we just look for signals again.
2019 */
2020 spin_lock(&lp->lwp_spin);
2021 lwp_delsig(lp, sig, 1); /* clear old signal */
2022 spin_unlock(&lp->lwp_spin);
2023 sig = p->p_xstat;
2024 if (sig == 0) {
2025 /* haveptok is TRUE */
2026 lwkt_reltoken(&p->p_token);
2027 continue;
2028 }
2029
2030 /*
2031 * Put the new signal into p_siglist. If the
2032 * signal is being masked, look for other signals.
2033 *
2034 * XXX lwp might need a call to ksignal()
2035 */
2036 SIGADDSET_ATOMIC(p->p_siglist, sig);
2037 if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
2038 /* haveptok is TRUE */
2039 lwkt_reltoken(&p->p_token);
2040 continue;
2041 }
2042
2043 /*
2044 * If the traced bit got turned off, go back up
2045 * to the top to rescan signals. This ensures
2046 * that p_sig* and ps_sigact are consistent.
2047 */
2048 if ((p->p_flags & P_TRACED) == 0) {
2049 /* haveptok is TRUE */
2050 lwkt_reltoken(&p->p_token);
2051 continue;
2052 }
2053 }
2054
2055 /*
2056 * p_token may be held here
2057 */
2058 prop = sigprop(sig);
2059
2060 /*
2061 * Decide whether the signal should be returned.
2062 * Return the signal's number, or fall through
2063 * to clear it from the pending mask.
2064 */
2065 switch ((intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)]) {
2066 case (intptr_t)SIG_DFL:
2067 /*
2068 * Don't take default actions on system processes.
2069 */
2070 if (p->p_pid <= 1) {
2071 #ifdef DIAGNOSTIC
2072 /*
2073 * Are you sure you want to ignore SIGSEGV
2074 * in init? XXX
2075 */
2076 kprintf("Process (pid %lu) got signal %d\n",
2077 (u_long)p->p_pid, sig);
2078 #endif
2079 break; /* == ignore */
2080 }
2081
2082 /*
2083 * Handle the in-kernel checkpoint action
2084 */
2085 if (prop & SA_CKPT) {
2086 if (haveptok == 0) {
2087 lwkt_gettoken(&p->p_token);
2088 haveptok = 1;
2089 }
2090 checkpoint_signal_handler(lp);
2091 break;
2092 }
2093
2094 /*
2095 * If there is a pending stop signal to process
2096 * with default action, stop here,
2097 * then clear the signal. However,
2098 * if process is member of an orphaned
2099 * process group, ignore tty stop signals.
2100 */
2101 if (prop & SA_STOP) {
2102 if (haveptok == 0) {
2103 lwkt_gettoken(&p->p_token);
2104 haveptok = 1;
2105 }
2106 if (p->p_flags & P_TRACED ||
2107 (p->p_pgrp->pg_jobc == 0 &&
2108 prop & SA_TTYSTOP))
2109 break; /* == ignore */
2110 if ((p->p_flags & P_WEXIT) == 0) {
2111 p->p_xstat = sig;
2112 proc_stop(p, SSTOP);
2113 tstop();
2114 }
2115 break;
2116 } else if (prop & SA_IGNORE) {
2117 /*
2118 * Except for SIGCONT, shouldn't get here.
2119 * Default action is to ignore; drop it.
2120 */
2121 break; /* == ignore */
2122 } else {
2123 if (ptokp)
2124 *ptokp = haveptok;
2125 else if (haveptok)
2126 lwkt_reltoken(&p->p_token);
2127 return (sig);
2128 }
2129
2130 /*NOTREACHED*/
2131
2132 case (intptr_t)SIG_IGN:
2133 /*
2134 * Masking above should prevent us ever trying
2135 * to take action on an ignored signal other
2136 * than SIGCONT, unless process is traced.
2137 */
2138 if ((prop & SA_CONT) == 0 &&
2139 (p->p_flags & P_TRACED) == 0)
2140 kprintf("issignal\n");
2141 break; /* == ignore */
2142
2143 default:
2144 /*
2145 * This signal has an action, let
2146 * postsig() process it.
2147 */
2148 if (ptokp)
2149 *ptokp = haveptok;
2150 else if (haveptok)
2151 lwkt_reltoken(&p->p_token);
2152 return (sig);
2153 }
2154 spin_lock(&lp->lwp_spin);
2155 lwp_delsig(lp, sig, haveptok); /* take the signal! */
2156 spin_unlock(&lp->lwp_spin);
2157
2158 if (haveptok)
2159 lwkt_reltoken(&p->p_token);
2160 }
2161 /* NOTREACHED */
2162 }
2163
2164 /*
2165 * Take the action for the specified signal from the current set of
2166 * pending signals.
2167 *
2168 * haveptok indicates whether the caller is holding p->p_token. If the
2169 * caller is, we are responsible for releasing it.
2170 *
2171 * This routine can only be called from the top-level trap from usermode.
2172 * It is expecting to be able to modify the top-level stack frame.
2173 */
2174 void
2175 postsig(int sig, int haveptok)
2176 {
2177 struct lwp *lp = curthread->td_lwp;
2178 struct proc *p = lp->lwp_proc;
2179 struct sigacts *ps = p->p_sigacts;
2180 sig_t action;
2181 sigset_t returnmask;
2182 int code;
2183
2184 KASSERT(sig != 0, ("postsig"));
2185
2186 /*
2187 * If we are a virtual kernel running an emulated user process
2188 * context, switch back to the virtual kernel context before
2189 * trying to post the signal.
2190 */
2191 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
2192 struct trapframe *tf = lp->lwp_md.md_regs;
2193 tf->tf_trapno = 0;
2194 vkernel_trap(lp, tf);
2195 }
2196
2197 KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
2198
2199 spin_lock(&lp->lwp_spin);
2200 lwp_delsig(lp, sig, haveptok);
2201 spin_unlock(&lp->lwp_spin);
2202 action = ps->ps_sigact[_SIG_IDX(sig)];
2203 #ifdef KTRACE
2204 if (KTRPOINT(lp->lwp_thread, KTR_PSIG))
2205 ktrpsig(lp, sig, action, lp->lwp_flags & LWP_OLDMASK ?
2206 &lp->lwp_oldsigmask : &lp->lwp_sigmask, 0);
2207 #endif
2208 /*
2209 * We don't need p_token after this point.
2210 */
2211 if (haveptok)
2212 lwkt_reltoken(&p->p_token);
2213
2214 STOPEVENT(p, S_SIG, sig);
2215
2216 if (action == SIG_DFL) {
2217 /*
2218 * Default action, where the default is to kill
2219 * the process. (Other cases were ignored above.)
2220 */
2221 sigexit(lp, sig);
2222 /* NOTREACHED */
2223 } else {
2224 /*
2225 * If we get here, the signal must be caught.
2226 */
2227 KASSERT(action != SIG_IGN && !SIGISMEMBER(lp->lwp_sigmask, sig),
2228 ("postsig action"));
2229
2230 /*
2231 * Reset the signal handler if asked to
2232 */
2233 if (SIGISMEMBER(ps->ps_sigreset, sig)) {
2234 /*
2235 * See kern_sigaction() for origin of this code.
2236 */
2237 SIGDELSET(p->p_sigcatch, sig);
2238 if (sig != SIGCONT &&
2239 sigprop(sig) & SA_IGNORE)
2240 SIGADDSET(p->p_sigignore, sig);
2241 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
2242 }
2243
2244 /*
2245 * Set the signal mask and calculate the mask to restore
2246 * when the signal function returns.
2247 *
2248 * Special case: user has done a sigsuspend. Here the
2249 * current mask is not of interest, but rather the
2250 * mask from before the sigsuspend is what we want
2251 * restored after the signal processing is completed.
2252 */
2253 if (lp->lwp_flags & LWP_OLDMASK) {
2254 returnmask = lp->lwp_oldsigmask;
2255 lp->lwp_flags &= ~LWP_OLDMASK;
2256 } else {
2257 returnmask = lp->lwp_sigmask;
2258 }
2259
2260 SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
2261 if (!SIGISMEMBER(ps->ps_signodefer, sig))
2262 SIGADDSET(lp->lwp_sigmask, sig);
2263
2264 lp->lwp_ru.ru_nsignals++;
2265 if (lp->lwp_sig != sig) {
2266 code = 0;
2267 } else {
2268 code = lp->lwp_code;
2269 lp->lwp_code = 0;
2270 lp->lwp_sig = 0;
2271 }
2272 (*p->p_sysent->sv_sendsig)(action, sig, &returnmask, code);
2273 }
2274 }
2275
2276 /*
2277 * Kill the current process for stated reason.
2278 */
2279 void
2280 killproc(struct proc *p, char *why)
2281 {
2282 log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n",
2283 p->p_pid, p->p_comm,
2284 p->p_ucred ? p->p_ucred->cr_uid : -1, why);
2285 ksignal(p, SIGKILL);
2286 }
2287
2288 /*
2289 * Force the current process to exit with the specified signal, dumping core
2290 * if appropriate. We bypass the normal tests for masked and caught signals,
2291 * allowing unrecoverable failures to terminate the process without changing
2292 * signal state. Mark the accounting record with the signal termination.
2293 * If dumping core, save the signal number for the debugger. Calls exit and
2294 * does not return.
2295 *
2296 * This routine does not return.
2297 */
2298 void
2299 sigexit(struct lwp *lp, int sig)
2300 {
2301 struct proc *p = lp->lwp_proc;
2302
2303 lwkt_gettoken(&p->p_token);
2304 p->p_acflag |= AXSIG;
2305 if (sigprop(sig) & SA_CORE) {
2306 lp->lwp_sig = sig;
2307
2308 /*
2309 * All threads must be stopped before we can safely coredump.
2310 * Stop threads using SCORE, which cannot be overridden.
2311 */
2312 if (p->p_stat != SCORE) {
2313 proc_stop(p, SCORE);
2314 proc_stopwait(p);
2315
2316 if (coredump(lp, sig) == 0)
2317 sig |= WCOREFLAG;
2318 p->p_stat = SSTOP;
2319 }
2320
2321 /*
2322 * Log signals which would cause core dumps
2323 * (Log as LOG_INFO to appease those who don't want
2324 * these messages.)
2325 * XXX : Todo, as well as euid, write out ruid too
2326 */
2327 if (kern_logsigexit) {
2328 log(LOG_INFO,
2329 "pid %d (%s), uid %d: exited on signal %d%s\n",
2330 p->p_pid, p->p_comm,
2331 p->p_ucred ? p->p_ucred->cr_uid : -1,
2332 sig &~ WCOREFLAG,
2333 sig & WCOREFLAG ? " (core dumped)" : "");
2334 }
2335 }
2336 lwkt_reltoken(&p->p_token);
2337 exit1(W_EXITCODE(0, sig));
2338 /* NOTREACHED */
2339 }
2340
2341 static char corefilename[MAXPATHLEN+1] = {"%N.core"};
2342 SYSCTL_STRING(_kern, OID_AUTO, corefile, CTLFLAG_RW, corefilename,
2343 sizeof(corefilename), "process corefile name format string");
2344
2345 /*
2346 * expand_name(name, uid, pid)
2347 * Expand the name described in corefilename, using name, uid, and pid.
2348 * corefilename is a kprintf-like string, with three format specifiers:
2349 * %N name of process ("name")
2350 * %P process id (pid)
2351 * %U user id (uid)
2352 * For example, "%N.core" is the default; they can be disabled completely
2353 * by using "/dev/null", or all core files can be stored in "/cores/%U/%N-%P".
2354 * This is controlled by the sysctl variable kern.corefile (see above).
2355 */
2356
2357 static char *
2358 expand_name(const char *name, uid_t uid, pid_t pid)
2359 {
2360 char *temp;
2361 char buf[11]; /* Buffer for pid/uid -- max 4B */
2362 int i, n;
2363 char *format = corefilename;
2364 size_t namelen;
2365
2366 temp = kmalloc(MAXPATHLEN + 1, M_TEMP, M_NOWAIT);
2367 if (temp == NULL)
2368 return NULL;
2369 namelen = strlen(name);
2370 for (i = 0, n = 0; n < MAXPATHLEN && format[i]; i++) {
2371 int l;
2372 switch (format[i]) {
2373 case '%': /* Format character */
2374 i++;
2375 switch (format[i]) {
2376 case '%':
2377 temp[n++] = '%';
2378 break;
2379 case 'N': /* process name */
2380 if ((n + namelen) > MAXPATHLEN) {
2381 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n",
2382 pid, name, uid, temp, name);
2383 kfree(temp, M_TEMP);
2384 return NULL;
2385 }
2386 memcpy(temp+n, name, namelen);
2387 n += namelen;
2388 break;
2389 case 'P': /* process id */
2390 l = ksprintf(buf, "%u", pid);
2391 if ((n + l) > MAXPATHLEN) {
2392 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n",
2393 pid, name, uid, temp, name);
2394 kfree(temp, M_TEMP);
2395 return NULL;
2396 }
2397 memcpy(temp+n, buf, l);
2398 n += l;
2399 break;
2400 case 'U': /* user id */
2401 l = ksprintf(buf, "%u", uid);
2402 if ((n + l) > MAXPATHLEN) {
2403 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n",
2404 pid, name, uid, temp, name);
2405 kfree(temp, M_TEMP);
2406 return NULL;
2407 }
2408 memcpy(temp+n, buf, l);
2409 n += l;
2410 break;
2411 default:
2412 log(LOG_ERR, "Unknown format character %c in `%s'\n", format[i], format);
2413 }
2414 break;
2415 default:
2416 temp[n++] = format[i];
2417 }
2418 }
2419 temp[n] = '\0';
2420 return temp;
2421 }
2422
2423 /*
2424 * Dump a process' core. The main routine does some
2425 * policy checking, and creates the name of the coredump;
2426 * then it passes on a vnode and a size limit to the process-specific
2427 * coredump routine if there is one; if there _is not_ one, it returns
2428 * ENOSYS; otherwise it returns the error from the process-specific routine.
2429 *
2430 * The parameter `lp' is the lwp which triggered the coredump.
2431 */
2432
2433 static int
2434 coredump(struct lwp *lp, int sig)
2435 {
2436 struct proc *p = lp->lwp_proc;
2437 struct vnode *vp;
2438 struct ucred *cred = p->p_ucred;
2439 struct flock lf;
2440 struct nlookupdata nd;
2441 struct vattr vattr;
2442 int error, error1;
2443 char *name; /* name of corefile */
2444 off_t limit;
2445
2446 STOPEVENT(p, S_CORE, 0);
2447
2448 if (((sugid_coredump == 0) && p->p_flags & P_SUGID) || do_coredump == 0)
2449 return (EFAULT);
2450
2451 /*
2452 * Note that the bulk of limit checking is done after
2453 * the corefile is created. The exception is if the limit
2454 * for corefiles is 0, in which case we don't bother
2455 * creating the corefile at all. This layout means that
2456 * a corefile is truncated instead of not being created,
2457 * if it is larger than the limit.
2458 */
2459 limit = p->p_rlimit[RLIMIT_CORE].rlim_cur;
2460 if (limit == 0)
2461 return EFBIG;
2462
2463 name = expand_name(p->p_comm, p->p_ucred->cr_uid, p->p_pid);
2464 if (name == NULL)
2465 return (EINVAL);
2466 error = nlookup_init(&nd, name, UIO_SYSSPACE, NLC_LOCKVP);
2467 if (error == 0)
2468 error = vn_open(&nd, NULL,
2469 O_CREAT | FWRITE | O_NOFOLLOW,
2470 S_IRUSR | S_IWUSR);
2471 kfree(name, M_TEMP);
2472 if (error) {
2473 nlookup_done(&nd);
2474 return (error);
2475 }
2476 vp = nd.nl_open_vp;
2477 nd.nl_open_vp = NULL;
2478 nlookup_done(&nd);
2479
2480 vn_unlock(vp);
2481 lf.l_whence = SEEK_SET;
2482 lf.l_start = 0;
2483 lf.l_len = 0;
2484 lf.l_type = F_WRLCK;
2485 error = VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &lf, 0);
2486 if (error)
2487 goto out2;
2488
2489 /* Don't dump to non-regular files or files with links. */
2490 if (vp->v_type != VREG ||
2491 VOP_GETATTR(vp, &vattr) || vattr.va_nlink != 1) {
2492 error = EFAULT;
2493 goto out1;
2494 }
2495
2496 /* Don't dump to files current user does not own */
2497 if (vattr.va_uid != p->p_ucred->cr_uid) {
2498 error = EFAULT;
2499 goto out1;
2500 }
2501
2502 VATTR_NULL(&vattr);
2503 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
2504 vattr.va_size = 0;
2505 VOP_SETATTR(vp, &vattr, cred);
2506 p->p_acflag |= ACORE;
2507 vn_unlock(vp);
2508
2509 error = p->p_sysent->sv_coredump ?
2510 p->p_sysent->sv_coredump(lp, sig, vp, limit) : ENOSYS;
2511
2512 out1:
2513 lf.l_type = F_UNLCK;
2514 VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &lf, 0);
2515 out2:
2516 error1 = vn_close(vp, FWRITE, NULL);
2517 if (error == 0)
2518 error = error1;
2519 return (error);
2520 }
2521
2522 /*
2523 * Nonexistent system call-- signal process (may want to handle it).
2524 * Flag error in case process won't see signal immediately (blocked or ignored).
2525 *
2526 * MPALMOSTSAFE
2527 */
2528 /* ARGSUSED */
2529 int
2530 sys_nosys(struct nosys_args *args)
2531 {
2532 lwpsignal(curproc, curthread->td_lwp, SIGSYS);
2533 return (EINVAL);
2534 }
2535
2536 /*
2537 * Send a SIGIO or SIGURG signal to a process or process group using
2538 * stored credentials rather than those of the current process.
2539 */
2540 void
2541 pgsigio(struct sigio *sigio, int sig, int checkctty)
2542 {
2543 if (sigio == NULL)
2544 return;
2545
2546 if (sigio->sio_pgid > 0) {
2547 if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred,
2548 sigio->sio_proc))
2549 ksignal(sigio->sio_proc, sig);
2550 } else if (sigio->sio_pgid < 0) {
2551 struct proc *p;
2552 struct pgrp *pg = sigio->sio_pgrp;
2553
2554 /*
2555 * Must interlock all signals against fork
2556 */
2557 pgref(pg);
2558 lockmgr(&pg->pg_lock, LK_EXCLUSIVE);
2559 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
2560 if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, p) &&
2561 (checkctty == 0 || (p->p_flags & P_CONTROLT)))
2562 ksignal(p, sig);
2563 }
2564 lockmgr(&pg->pg_lock, LK_RELEASE);
2565 pgrel(pg);
2566 }
2567 }
2568
2569 static int
2570 filt_sigattach(struct knote *kn)
2571 {
2572 struct proc *p = curproc;
2573
2574 kn->kn_ptr.p_proc = p;
2575 kn->kn_flags |= EV_CLEAR; /* automatically set */
2576
2577 /* XXX lock the proc here while adding to the list? */
2578 knote_insert(&p->p_klist, kn);
2579
2580 return (0);
2581 }
2582
2583 static void
2584 filt_sigdetach(struct knote *kn)
2585 {
2586 struct proc *p = kn->kn_ptr.p_proc;
2587
2588 knote_remove(&p->p_klist, kn);
2589 }
2590
2591 /*
2592 * signal knotes are shared with proc knotes, so we apply a mask to
2593 * the hint in order to differentiate them from process hints. This
2594 * could be avoided by using a signal-specific knote list, but probably
2595 * isn't worth the trouble.
2596 */
2597 static int
2598 filt_signal(struct knote *kn, long hint)
2599 {
2600 if (hint & NOTE_SIGNAL) {
2601 hint &= ~NOTE_SIGNAL;
2602
2603 if (kn->kn_id == hint)
2604 kn->kn_data++;
2605 }
2606 return (kn->kn_data != 0);
2607 }
DragonFly BSD