xref: /freebsd/sys/kern/kern_sig.c (revision 3e0f6b97b257a96f7275e4442204263e44b16686)
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. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)kern_sig.c	8.7 (Berkeley) 4/18/94
39  * $FreeBSD$
40  */
41 
42 #include "opt_ktrace.h"
43 
44 #define	SIGPROP		/* include signal properties table */
45 #include <sys/param.h>
46 #include <sys/sysproto.h>
47 #include <sys/signalvar.h>
48 #include <sys/resourcevar.h>
49 #include <sys/namei.h>
50 #include <sys/vnode.h>
51 #include <sys/proc.h>
52 #include <sys/systm.h>
53 #include <sys/timeb.h>
54 #include <sys/times.h>
55 #include <sys/buf.h>
56 #include <sys/acct.h>
57 #include <sys/file.h>
58 #include <sys/kernel.h>
59 #include <sys/wait.h>
60 #include <sys/ktrace.h>
61 #include <sys/syslog.h>
62 #include <sys/stat.h>
63 #include <sys/sysent.h>
64 
65 #include <machine/cpu.h>
66 
67 #include <vm/vm.h>
68 #include <vm/vm_param.h>
69 #include <vm/vm_prot.h>
70 #include <sys/lock.h>
71 #include <vm/pmap.h>
72 #include <vm/vm_map.h>
73 #include <sys/user.h>		/* for coredump */
74 
75 static int coredump     __P((struct proc *p));
76 static int killpg1	__P((struct proc *cp, int signum, int pgid, int all));
77 static void stop	__P((struct proc *));
78 
79 /*
80  * Can process p, with pcred pc, send the signal signum to process q?
81  */
82 #define CANSIGNAL(p, pc, q, signum) \
83 	((pc)->pc_ucred->cr_uid == 0 || \
84 	    (pc)->p_ruid == (q)->p_cred->p_ruid || \
85 	    (pc)->pc_ucred->cr_uid == (q)->p_cred->p_ruid || \
86 	    (pc)->p_ruid == (q)->p_ucred->cr_uid || \
87 	    (pc)->pc_ucred->cr_uid == (q)->p_ucred->cr_uid || \
88 	    ((signum) == SIGCONT && (q)->p_session == (p)->p_session))
89 
90 #ifndef _SYS_SYSPROTO_H_
91 struct sigaction_args {
92 	int	signum;
93 	struct	sigaction *nsa;
94 	struct	sigaction *osa;
95 };
96 #endif
97 /* ARGSUSED */
98 int
99 sigaction(p, uap, retval)
100 	struct proc *p;
101 	register struct sigaction_args *uap;
102 	int *retval;
103 {
104 	struct sigaction vec;
105 	register struct sigaction *sa;
106 	register struct sigacts *ps = p->p_sigacts;
107 	register int signum;
108 	int bit, error;
109 
110 	signum = uap->signum;
111 	if (signum <= 0 || signum >= NSIG)
112 		return (EINVAL);
113 	sa = &vec;
114 	if (uap->osa) {
115 		sa->sa_handler = ps->ps_sigact[signum];
116 		sa->sa_mask = ps->ps_catchmask[signum];
117 		bit = sigmask(signum);
118 		sa->sa_flags = 0;
119 		if ((ps->ps_sigonstack & bit) != 0)
120 			sa->sa_flags |= SA_ONSTACK;
121 		if ((ps->ps_sigintr & bit) == 0)
122 			sa->sa_flags |= SA_RESTART;
123 		if ((ps->ps_sigreset & bit) != 0)
124 			sa->sa_flags |= SA_RESETHAND;
125 		if ((ps->ps_signodefer & bit) != 0)
126 			sa->sa_flags |= SA_NODEFER;
127 		if (signum == SIGCHLD && p->p_flag & P_NOCLDSTOP)
128 			sa->sa_flags |= SA_NOCLDSTOP;
129 		if ((error = copyout((caddr_t)sa, (caddr_t)uap->osa,
130 		    sizeof (vec))))
131 			return (error);
132 	}
133 	if (uap->nsa) {
134 		if ((error = copyin((caddr_t)uap->nsa, (caddr_t)sa,
135 		    sizeof (vec))))
136 			return (error);
137 		if ((signum == SIGKILL || signum == SIGSTOP) &&
138 		    sa->sa_handler != SIG_DFL)
139 			return (EINVAL);
140 		setsigvec(p, signum, sa);
141 	}
142 	return (0);
143 }
144 
145 void
146 setsigvec(p, signum, sa)
147 	register struct proc *p;
148 	int signum;
149 	register struct sigaction *sa;
150 {
151 	register struct sigacts *ps = p->p_sigacts;
152 	register int bit;
153 
154 	bit = sigmask(signum);
155 	/*
156 	 * Change setting atomically.
157 	 */
158 	(void) splhigh();
159 	ps->ps_sigact[signum] = sa->sa_handler;
160 	ps->ps_catchmask[signum] = sa->sa_mask &~ sigcantmask;
161 	if ((sa->sa_flags & SA_RESTART) == 0)
162 		ps->ps_sigintr |= bit;
163 	else
164 		ps->ps_sigintr &= ~bit;
165 	if (sa->sa_flags & SA_ONSTACK)
166 		ps->ps_sigonstack |= bit;
167 	else
168 		ps->ps_sigonstack &= ~bit;
169 	if (sa->sa_flags & SA_RESETHAND)
170 		ps->ps_sigreset |= bit;
171 	else
172 		ps->ps_sigreset &= ~bit;
173 	if (sa->sa_flags & SA_NODEFER)
174 		ps->ps_signodefer |= bit;
175 	else
176 		ps->ps_signodefer &= ~bit;
177 #ifdef COMPAT_SUNOS
178 	if (sa->sa_flags & SA_USERTRAMP)
179 		ps->ps_usertramp |= bit;
180 	else
181 		ps->ps_usertramp &= ~bit;
182 #endif
183 	if (signum == SIGCHLD) {
184 		if (sa->sa_flags & SA_NOCLDSTOP)
185 			p->p_flag |= P_NOCLDSTOP;
186 		else
187 			p->p_flag &= ~P_NOCLDSTOP;
188 	}
189 	/*
190 	 * Set bit in p_sigignore for signals that are set to SIG_IGN,
191 	 * and for signals set to SIG_DFL where the default is to ignore.
192 	 * However, don't put SIGCONT in p_sigignore,
193 	 * as we have to restart the process.
194 	 */
195 	if (sa->sa_handler == SIG_IGN ||
196 	    (sigprop[signum] & SA_IGNORE && sa->sa_handler == SIG_DFL)) {
197 		p->p_siglist &= ~bit;		/* never to be seen again */
198 		if (signum != SIGCONT)
199 			p->p_sigignore |= bit;	/* easier in psignal */
200 		p->p_sigcatch &= ~bit;
201 	} else {
202 		p->p_sigignore &= ~bit;
203 		if (sa->sa_handler == SIG_DFL)
204 			p->p_sigcatch &= ~bit;
205 		else
206 			p->p_sigcatch |= bit;
207 	}
208 	(void) spl0();
209 }
210 
211 /*
212  * Initialize signal state for process 0;
213  * set to ignore signals that are ignored by default.
214  */
215 void
216 siginit(p)
217 	struct proc *p;
218 {
219 	register int i;
220 
221 	for (i = 0; i < NSIG; i++)
222 		if (sigprop[i] & SA_IGNORE && i != SIGCONT)
223 			p->p_sigignore |= sigmask(i);
224 }
225 
226 /*
227  * Reset signals for an exec of the specified process.
228  */
229 void
230 execsigs(p)
231 	register struct proc *p;
232 {
233 	register struct sigacts *ps = p->p_sigacts;
234 	register int nc, mask;
235 
236 	/*
237 	 * Reset caught signals.  Held signals remain held
238 	 * through p_sigmask (unless they were caught,
239 	 * and are now ignored by default).
240 	 */
241 	while (p->p_sigcatch) {
242 		nc = ffs((long)p->p_sigcatch);
243 		mask = sigmask(nc);
244 		p->p_sigcatch &= ~mask;
245 		if (sigprop[nc] & SA_IGNORE) {
246 			if (nc != SIGCONT)
247 				p->p_sigignore |= mask;
248 			p->p_siglist &= ~mask;
249 		}
250 		ps->ps_sigact[nc] = SIG_DFL;
251 	}
252 	/*
253 	 * Reset stack state to the user stack.
254 	 * Clear set of signals caught on the signal stack.
255 	 */
256 	ps->ps_sigstk.ss_flags = SS_DISABLE;
257 	ps->ps_sigstk.ss_size = 0;
258 	ps->ps_sigstk.ss_sp = 0;
259 	ps->ps_flags = 0;
260 }
261 
262 /*
263  * Manipulate signal mask.
264  * Note that we receive new mask, not pointer,
265  * and return old mask as return value;
266  * the library stub does the rest.
267  */
268 #ifndef _SYS_SYSPROTO_H_
269 struct sigprocmask_args {
270 	int	how;
271 	sigset_t mask;
272 };
273 #endif
274 int
275 sigprocmask(p, uap, retval)
276 	register struct proc *p;
277 	struct sigprocmask_args *uap;
278 	int *retval;
279 {
280 	int error = 0;
281 
282 	*retval = p->p_sigmask;
283 	(void) splhigh();
284 
285 	switch (uap->how) {
286 	case SIG_BLOCK:
287 		p->p_sigmask |= uap->mask &~ sigcantmask;
288 		break;
289 
290 	case SIG_UNBLOCK:
291 		p->p_sigmask &= ~uap->mask;
292 		break;
293 
294 	case SIG_SETMASK:
295 		p->p_sigmask = uap->mask &~ sigcantmask;
296 		break;
297 
298 	default:
299 		error = EINVAL;
300 		break;
301 	}
302 	(void) spl0();
303 	return (error);
304 }
305 
306 #ifndef _SYS_SYSPROTO_H_
307 struct sigpending_args {
308 	int	dummy;
309 };
310 #endif
311 /* ARGSUSED */
312 int
313 sigpending(p, uap, retval)
314 	struct proc *p;
315 	struct sigpending_args *uap;
316 	int *retval;
317 {
318 
319 	*retval = p->p_siglist;
320 	return (0);
321 }
322 
323 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
324 /*
325  * Generalized interface signal handler, 4.3-compatible.
326  */
327 #ifndef _SYS_SYSPROTO_H_
328 struct osigvec_args {
329 	int	signum;
330 	struct	sigvec *nsv;
331 	struct	sigvec *osv;
332 };
333 #endif
334 /* ARGSUSED */
335 int
336 osigvec(p, uap, retval)
337 	struct proc *p;
338 	register struct osigvec_args *uap;
339 	int *retval;
340 {
341 	struct sigvec vec;
342 	register struct sigacts *ps = p->p_sigacts;
343 	register struct sigvec *sv;
344 	register int signum;
345 	int bit, error;
346 
347 	signum = uap->signum;
348 	if (signum <= 0 || signum >= NSIG)
349 		return (EINVAL);
350 	sv = &vec;
351 	if (uap->osv) {
352 		*(sig_t *)&sv->sv_handler = ps->ps_sigact[signum];
353 		sv->sv_mask = ps->ps_catchmask[signum];
354 		bit = sigmask(signum);
355 		sv->sv_flags = 0;
356 		if ((ps->ps_sigonstack & bit) != 0)
357 			sv->sv_flags |= SV_ONSTACK;
358 		if ((ps->ps_sigintr & bit) != 0)
359 			sv->sv_flags |= SV_INTERRUPT;
360 		if ((ps->ps_sigreset & bit) != 0)
361 			sv->sv_flags |= SV_RESETHAND;
362 		if ((ps->ps_signodefer & bit) != 0)
363 			sv->sv_flags |= SV_NODEFER;
364 #ifndef COMPAT_SUNOS
365 		if (signum == SIGCHLD && p->p_flag & P_NOCLDSTOP)
366 			sv->sv_flags |= SV_NOCLDSTOP;
367 #endif
368 		if ((error = copyout((caddr_t)sv, (caddr_t)uap->osv,
369 		    sizeof (vec))))
370 			return (error);
371 	}
372 	if (uap->nsv) {
373 		if ((error = copyin((caddr_t)uap->nsv, (caddr_t)sv,
374 		    sizeof (vec))))
375 			return (error);
376 		if ((signum == SIGKILL || signum == SIGSTOP) &&
377 		    sv->sv_handler != SIG_DFL)
378 			return (EINVAL);
379 #ifdef COMPAT_SUNOS
380 		sv->sv_flags |= SA_USERTRAMP;
381 #endif
382 		sv->sv_flags ^= SA_RESTART;	/* opposite of SV_INTERRUPT */
383 		setsigvec(p, signum, (struct sigaction *)sv);
384 	}
385 	return (0);
386 }
387 
388 #ifndef _SYS_SYSPROTO_H_
389 struct osigblock_args {
390 	int	mask;
391 };
392 #endif
393 int
394 osigblock(p, uap, retval)
395 	register struct proc *p;
396 	struct osigblock_args *uap;
397 	int *retval;
398 {
399 
400 	(void) splhigh();
401 	*retval = p->p_sigmask;
402 	p->p_sigmask |= uap->mask &~ sigcantmask;
403 	(void) spl0();
404 	return (0);
405 }
406 
407 #ifndef _SYS_SYSPROTO_H_
408 struct osigsetmask_args {
409 	int	mask;
410 };
411 #endif
412 int
413 osigsetmask(p, uap, retval)
414 	struct proc *p;
415 	struct osigsetmask_args *uap;
416 	int *retval;
417 {
418 
419 	(void) splhigh();
420 	*retval = p->p_sigmask;
421 	p->p_sigmask = uap->mask &~ sigcantmask;
422 	(void) spl0();
423 	return (0);
424 }
425 #endif /* COMPAT_43 || COMPAT_SUNOS */
426 
427 /*
428  * Suspend process until signal, providing mask to be set
429  * in the meantime.  Note nonstandard calling convention:
430  * libc stub passes mask, not pointer, to save a copyin.
431  */
432 #ifndef _SYS_SYSPROTO_H_
433 struct sigsuspend_args {
434 	sigset_t mask;
435 };
436 #endif
437 /* ARGSUSED */
438 int
439 sigsuspend(p, uap, retval)
440 	register struct proc *p;
441 	struct sigsuspend_args *uap;
442 	int *retval;
443 {
444 	register struct sigacts *ps = p->p_sigacts;
445 
446 	/*
447 	 * When returning from sigpause, we want
448 	 * the old mask to be restored after the
449 	 * signal handler has finished.  Thus, we
450 	 * save it here and mark the sigacts structure
451 	 * to indicate this.
452 	 */
453 	ps->ps_oldmask = p->p_sigmask;
454 	ps->ps_flags |= SAS_OLDMASK;
455 	p->p_sigmask = uap->mask &~ sigcantmask;
456 	while (tsleep((caddr_t) ps, PPAUSE|PCATCH, "pause", 0) == 0)
457 		/* void */;
458 	/* always return EINTR rather than ERESTART... */
459 	return (EINTR);
460 }
461 
462 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
463 #ifndef _SYS_SYSPROTO_H_
464 struct osigstack_args {
465 	struct	sigstack *nss;
466 	struct	sigstack *oss;
467 };
468 #endif
469 /* ARGSUSED */
470 int
471 osigstack(p, uap, retval)
472 	struct proc *p;
473 	register struct osigstack_args *uap;
474 	int *retval;
475 {
476 	struct sigstack ss;
477 	struct sigacts *psp;
478 	int error = 0;
479 
480 	psp = p->p_sigacts;
481 	ss.ss_sp = psp->ps_sigstk.ss_sp;
482 	ss.ss_onstack = psp->ps_sigstk.ss_flags & SS_ONSTACK;
483 	if (uap->oss && (error = copyout((caddr_t)&ss, (caddr_t)uap->oss,
484 	    sizeof (struct sigstack))))
485 		return (error);
486 	if (uap->nss && (error = copyin((caddr_t)uap->nss, (caddr_t)&ss,
487 	    sizeof (ss))) == 0) {
488 		psp->ps_sigstk.ss_sp = ss.ss_sp;
489 		psp->ps_sigstk.ss_size = 0;
490 		psp->ps_sigstk.ss_flags |= ss.ss_onstack & SS_ONSTACK;
491 		psp->ps_flags |= SAS_ALTSTACK;
492 	}
493 	return (error);
494 }
495 #endif /* COMPAT_43 || COMPAT_SUNOS */
496 
497 #ifndef _SYS_SYSPROTO_H_
498 struct sigaltstack_args {
499 	struct	sigaltstack *nss;
500 	struct	sigaltstack *oss;
501 };
502 #endif
503 /* ARGSUSED */
504 int
505 sigaltstack(p, uap, retval)
506 	struct proc *p;
507 	register struct sigaltstack_args *uap;
508 	int *retval;
509 {
510 	struct sigacts *psp;
511 	struct sigaltstack ss;
512 	int error;
513 
514 	psp = p->p_sigacts;
515 	if ((psp->ps_flags & SAS_ALTSTACK) == 0)
516 		psp->ps_sigstk.ss_flags |= SS_DISABLE;
517 	if (uap->oss && (error = copyout((caddr_t)&psp->ps_sigstk,
518 	    (caddr_t)uap->oss, sizeof (struct sigaltstack))))
519 		return (error);
520 	if (uap->nss == 0)
521 		return (0);
522 	if ((error = copyin((caddr_t)uap->nss, (caddr_t)&ss, sizeof (ss))))
523 		return (error);
524 	if (ss.ss_flags & SS_DISABLE) {
525 		if (psp->ps_sigstk.ss_flags & SS_ONSTACK)
526 			return (EINVAL);
527 		psp->ps_flags &= ~SAS_ALTSTACK;
528 		psp->ps_sigstk.ss_flags = ss.ss_flags;
529 		return (0);
530 	}
531 	if (ss.ss_size < MINSIGSTKSZ)
532 		return (ENOMEM);
533 	psp->ps_flags |= SAS_ALTSTACK;
534 	psp->ps_sigstk= ss;
535 	return (0);
536 }
537 
538 /*
539  * Common code for kill process group/broadcast kill.
540  * cp is calling process.
541  */
542 int
543 killpg1(cp, signum, pgid, all)
544 	register struct proc *cp;
545 	int signum, pgid, all;
546 {
547 	register struct proc *p;
548 	register struct pcred *pc = cp->p_cred;
549 	struct pgrp *pgrp;
550 	int nfound = 0;
551 
552 	if (all)
553 		/*
554 		 * broadcast
555 		 */
556 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
557 			if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
558 			    p == cp || !CANSIGNAL(cp, pc, p, signum))
559 				continue;
560 			nfound++;
561 			if (signum)
562 				psignal(p, signum);
563 		}
564 	else {
565 		if (pgid == 0)
566 			/*
567 			 * zero pgid means send to my process group.
568 			 */
569 			pgrp = cp->p_pgrp;
570 		else {
571 			pgrp = pgfind(pgid);
572 			if (pgrp == NULL)
573 				return (ESRCH);
574 		}
575 		for (p = pgrp->pg_members.lh_first; p != 0;
576 		     p = p->p_pglist.le_next) {
577 			if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
578 			    p->p_stat == SZOMB ||
579 			    !CANSIGNAL(cp, pc, p, signum))
580 				continue;
581 			nfound++;
582 			if (signum)
583 				psignal(p, signum);
584 		}
585 	}
586 	return (nfound ? 0 : ESRCH);
587 }
588 
589 #ifndef _SYS_SYSPROTO_H_
590 struct kill_args {
591 	int	pid;
592 	int	signum;
593 };
594 #endif
595 /* ARGSUSED */
596 int
597 kill(cp, uap, retval)
598 	register struct proc *cp;
599 	register struct kill_args *uap;
600 	int *retval;
601 {
602 	register struct proc *p;
603 	register struct pcred *pc = cp->p_cred;
604 
605 	if ((u_int)uap->signum >= NSIG)
606 		return (EINVAL);
607 	if (uap->pid > 0) {
608 		/* kill single process */
609 		if ((p = pfind(uap->pid)) == NULL)
610 			return (ESRCH);
611 		if (!CANSIGNAL(cp, pc, p, uap->signum))
612 			return (EPERM);
613 		if (uap->signum)
614 			psignal(p, uap->signum);
615 		return (0);
616 	}
617 	switch (uap->pid) {
618 	case -1:		/* broadcast signal */
619 		return (killpg1(cp, uap->signum, 0, 1));
620 	case 0:			/* signal own process group */
621 		return (killpg1(cp, uap->signum, 0, 0));
622 	default:		/* negative explicit process group */
623 		return (killpg1(cp, uap->signum, -uap->pid, 0));
624 	}
625 	/* NOTREACHED */
626 }
627 
628 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
629 #ifndef _SYS_SYSPROTO_H_
630 struct okillpg_args {
631 	int	pgid;
632 	int	signum;
633 };
634 #endif
635 /* ARGSUSED */
636 int
637 okillpg(p, uap, retval)
638 	struct proc *p;
639 	register struct okillpg_args *uap;
640 	int *retval;
641 {
642 
643 	if ((u_int)uap->signum >= NSIG)
644 		return (EINVAL);
645 	return (killpg1(p, uap->signum, uap->pgid, 0));
646 }
647 #endif /* COMPAT_43 || COMPAT_SUNOS */
648 
649 /*
650  * Send a signal to a process group.
651  */
652 void
653 gsignal(pgid, signum)
654 	int pgid, signum;
655 {
656 	struct pgrp *pgrp;
657 
658 	if (pgid && (pgrp = pgfind(pgid)))
659 		pgsignal(pgrp, signum, 0);
660 }
661 
662 /*
663  * Send a signal to a process group.  If checktty is 1,
664  * limit to members which have a controlling terminal.
665  */
666 void
667 pgsignal(pgrp, signum, checkctty)
668 	struct pgrp *pgrp;
669 	int signum, checkctty;
670 {
671 	register struct proc *p;
672 
673 	if (pgrp)
674 		for (p = pgrp->pg_members.lh_first; p != 0;
675 		     p = p->p_pglist.le_next)
676 			if (checkctty == 0 || p->p_flag & P_CONTROLT)
677 				psignal(p, signum);
678 }
679 
680 /*
681  * Send a signal caused by a trap to the current process.
682  * If it will be caught immediately, deliver it with correct code.
683  * Otherwise, post it normally.
684  */
685 void
686 trapsignal(p, signum, code)
687 	struct proc *p;
688 	register int signum;
689 	u_long code;
690 {
691 	register struct sigacts *ps = p->p_sigacts;
692 	int mask;
693 
694 	mask = sigmask(signum);
695 	if ((p->p_flag & P_TRACED) == 0 && (p->p_sigcatch & mask) != 0 &&
696 	    (p->p_sigmask & mask) == 0) {
697 		p->p_stats->p_ru.ru_nsignals++;
698 #ifdef KTRACE
699 		if (KTRPOINT(p, KTR_PSIG))
700 			ktrpsig(p->p_tracep, signum, ps->ps_sigact[signum],
701 				p->p_sigmask, code);
702 #endif
703 		(*p->p_sysent->sv_sendsig)(ps->ps_sigact[signum], signum,
704 						p->p_sigmask, code);
705 		p->p_sigmask |= ps->ps_catchmask[signum] |
706 				(mask & ~ps->ps_signodefer);
707 		if ((ps->ps_sigreset & mask) != 0) {
708 			/*
709 			 * See setsigvec() for origin of this code.
710 			 */
711 			p->p_sigcatch &= ~mask;
712 			if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
713 				p->p_sigignore |= mask;
714 			ps->ps_sigact[signum] = SIG_DFL;
715 		}
716 	} else {
717 		ps->ps_code = code;	/* XXX for core dump/debugger */
718 		ps->ps_sig = signum;	/* XXX to verify code */
719 		psignal(p, signum);
720 	}
721 }
722 
723 /*
724  * Send the signal to the process.  If the signal has an action, the action
725  * is usually performed by the target process rather than the caller; we add
726  * the signal to the set of pending signals for the process.
727  *
728  * Exceptions:
729  *   o When a stop signal is sent to a sleeping process that takes the
730  *     default action, the process is stopped without awakening it.
731  *   o SIGCONT restarts stopped processes (or puts them back to sleep)
732  *     regardless of the signal action (eg, blocked or ignored).
733  *
734  * Other ignored signals are discarded immediately.
735  */
736 void
737 psignal(p, signum)
738 	register struct proc *p;
739 	register int signum;
740 {
741 	register int s, prop;
742 	register sig_t action;
743 	int mask;
744 
745 	if ((u_int)signum >= NSIG || signum == 0)
746 		panic("psignal signal number");
747 	mask = sigmask(signum);
748 	prop = sigprop[signum];
749 
750 	/*
751 	 * If proc is traced, always give parent a chance.
752 	 */
753 	if (p->p_flag & P_TRACED)
754 		action = SIG_DFL;
755 	else {
756 		/*
757 		 * If the signal is being ignored,
758 		 * then we forget about it immediately.
759 		 * (Note: we don't set SIGCONT in p_sigignore,
760 		 * and if it is set to SIG_IGN,
761 		 * action will be SIG_DFL here.)
762 		 */
763 		if (p->p_sigignore & mask)
764 			return;
765 		if (p->p_sigmask & mask)
766 			action = SIG_HOLD;
767 		else if (p->p_sigcatch & mask)
768 			action = SIG_CATCH;
769 		else
770 			action = SIG_DFL;
771 	}
772 
773 	if (p->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) &&
774 	    (p->p_flag & P_TRACED) == 0)
775 		p->p_nice = NZERO;
776 
777 	if (prop & SA_CONT)
778 		p->p_siglist &= ~stopsigmask;
779 
780 	if (prop & SA_STOP) {
781 		/*
782 		 * If sending a tty stop signal to a member of an orphaned
783 		 * process group, discard the signal here if the action
784 		 * is default; don't stop the process below if sleeping,
785 		 * and don't clear any pending SIGCONT.
786 		 */
787 		if (prop & SA_TTYSTOP && p->p_pgrp->pg_jobc == 0 &&
788 		    action == SIG_DFL)
789 		        return;
790 		p->p_siglist &= ~contsigmask;
791 	}
792 	p->p_siglist |= mask;
793 
794 	/*
795 	 * Defer further processing for signals which are held,
796 	 * except that stopped processes must be continued by SIGCONT.
797 	 */
798 	if (action == SIG_HOLD && ((prop & SA_CONT) == 0 || p->p_stat != SSTOP))
799 		return;
800 	s = splhigh();
801 	switch (p->p_stat) {
802 
803 	case SSLEEP:
804 		/*
805 		 * If process is sleeping uninterruptibly
806 		 * we can't interrupt the sleep... the signal will
807 		 * be noticed when the process returns through
808 		 * trap() or syscall().
809 		 */
810 		if ((p->p_flag & P_SINTR) == 0)
811 			goto out;
812 		/*
813 		 * Process is sleeping and traced... make it runnable
814 		 * so it can discover the signal in issignal() and stop
815 		 * for the parent.
816 		 */
817 		if (p->p_flag & P_TRACED)
818 			goto run;
819 		/*
820 		 * If SIGCONT is default (or ignored) and process is
821 		 * asleep, we are finished; the process should not
822 		 * be awakened.
823 		 */
824 		if ((prop & SA_CONT) && action == SIG_DFL) {
825 			p->p_siglist &= ~mask;
826 			goto out;
827 		}
828 		/*
829 		 * When a sleeping process receives a stop
830 		 * signal, process immediately if possible.
831 		 * All other (caught or default) signals
832 		 * cause the process to run.
833 		 */
834 		if (prop & SA_STOP) {
835 			if (action != SIG_DFL)
836 				goto runfast;
837 			/*
838 			 * If a child holding parent blocked,
839 			 * stopping could cause deadlock.
840 			 */
841 			if (p->p_flag & P_PPWAIT)
842 				goto out;
843 			p->p_siglist &= ~mask;
844 			p->p_xstat = signum;
845 			if ((p->p_pptr->p_flag & P_NOCLDSTOP) == 0)
846 				psignal(p->p_pptr, SIGCHLD);
847 			stop(p);
848 			goto out;
849 		} else
850 			goto runfast;
851 		/*NOTREACHED*/
852 
853 	case SSTOP:
854 		/*
855 		 * If traced process is already stopped,
856 		 * then no further action is necessary.
857 		 */
858 		if (p->p_flag & P_TRACED)
859 			goto out;
860 
861 		/*
862 		 * Kill signal always sets processes running.
863 		 */
864 		if (signum == SIGKILL)
865 			goto runfast;
866 
867 		if (prop & SA_CONT) {
868 			/*
869 			 * If SIGCONT is default (or ignored), we continue the
870 			 * process but don't leave the signal in p_siglist, as
871 			 * it has no further action.  If SIGCONT is held, we
872 			 * continue the process and leave the signal in
873 			 * p_siglist.  If the process catches SIGCONT, let it
874 			 * handle the signal itself.  If it isn't waiting on
875 			 * an event, then it goes back to run state.
876 			 * Otherwise, process goes back to sleep state.
877 			 */
878 			if (action == SIG_DFL)
879 				p->p_siglist &= ~mask;
880 			if (action == SIG_CATCH)
881 				goto runfast;
882 			if (p->p_wchan == 0)
883 				goto run;
884 			p->p_stat = SSLEEP;
885 			goto out;
886 		}
887 
888 		if (prop & SA_STOP) {
889 			/*
890 			 * Already stopped, don't need to stop again.
891 			 * (If we did the shell could get confused.)
892 			 */
893 			p->p_siglist &= ~mask;		/* take it away */
894 			goto out;
895 		}
896 
897 		/*
898 		 * If process is sleeping interruptibly, then simulate a
899 		 * wakeup so that when it is continued, it will be made
900 		 * runnable and can look at the signal.  But don't make
901 		 * the process runnable, leave it stopped.
902 		 */
903 		if (p->p_wchan && p->p_flag & P_SINTR)
904 			unsleep(p);
905 		goto out;
906 
907 	default:
908 		/*
909 		 * SRUN, SIDL, SZOMB do nothing with the signal,
910 		 * other than kicking ourselves if we are running.
911 		 * It will either never be noticed, or noticed very soon.
912 		 */
913 		if (p == curproc)
914 			signotify(p);
915 		goto out;
916 	}
917 	/*NOTREACHED*/
918 
919 runfast:
920 	/*
921 	 * Raise priority to at least PUSER.
922 	 */
923 	if (p->p_priority > PUSER)
924 		p->p_priority = PUSER;
925 run:
926 	setrunnable(p);
927 out:
928 	splx(s);
929 }
930 
931 /*
932  * If the current process has received a signal (should be caught or cause
933  * termination, should interrupt current syscall), return the signal number.
934  * Stop signals with default action are processed immediately, then cleared;
935  * they aren't returned.  This is checked after each entry to the system for
936  * a syscall or trap (though this can usually be done without calling issignal
937  * by checking the pending signal masks in the CURSIG macro.) The normal call
938  * sequence is
939  *
940  *	while (signum = CURSIG(curproc))
941  *		postsig(signum);
942  */
943 int
944 issignal(p)
945 	register struct proc *p;
946 {
947 	register int signum, mask, prop;
948 
949 	for (;;) {
950 		mask = p->p_siglist & ~p->p_sigmask;
951 		if (p->p_flag & P_PPWAIT)
952 			mask &= ~stopsigmask;
953 		if (mask == 0)	 	/* no signal to send */
954 			return (0);
955 		signum = ffs((long)mask);
956 		mask = sigmask(signum);
957 		prop = sigprop[signum];
958 		/*
959 		 * We should see pending but ignored signals
960 		 * only if P_TRACED was on when they were posted.
961 		 */
962 		if (mask & p->p_sigignore && (p->p_flag & P_TRACED) == 0) {
963 			p->p_siglist &= ~mask;
964 			continue;
965 		}
966 		if (p->p_flag & P_TRACED && (p->p_flag & P_PPWAIT) == 0) {
967 			/*
968 			 * If traced, always stop, and stay
969 			 * stopped until released by the parent.
970 			 */
971 			p->p_xstat = signum;
972 			psignal(p->p_pptr, SIGCHLD);
973 			do {
974 				stop(p);
975 				mi_switch();
976 			} while (!trace_req(p) && p->p_flag & P_TRACED);
977 
978 			/*
979 			 * If the traced bit got turned off, go back up
980 			 * to the top to rescan signals.  This ensures
981 			 * that p_sig* and ps_sigact are consistent.
982 			 */
983 			if ((p->p_flag & P_TRACED) == 0)
984 				continue;
985 
986 			/*
987 			 * If parent wants us to take the signal,
988 			 * then it will leave it in p->p_xstat;
989 			 * otherwise we just look for signals again.
990 			 */
991 			p->p_siglist &= ~mask;	/* clear the old signal */
992 			signum = p->p_xstat;
993 			if (signum == 0)
994 				continue;
995 
996 			/*
997 			 * Put the new signal into p_siglist.  If the
998 			 * signal is being masked, look for other signals.
999 			 */
1000 			mask = sigmask(signum);
1001 			p->p_siglist |= mask;
1002 			if (p->p_sigmask & mask)
1003 				continue;
1004 		}
1005 
1006 		/*
1007 		 * Decide whether the signal should be returned.
1008 		 * Return the signal's number, or fall through
1009 		 * to clear it from the pending mask.
1010 		 */
1011 		switch ((int)p->p_sigacts->ps_sigact[signum]) {
1012 
1013 		case (int)SIG_DFL:
1014 			/*
1015 			 * Don't take default actions on system processes.
1016 			 */
1017 			if (p->p_pid <= 1) {
1018 #ifdef DIAGNOSTIC
1019 				/*
1020 				 * Are you sure you want to ignore SIGSEGV
1021 				 * in init? XXX
1022 				 */
1023 				printf("Process (pid %lu) got signal %d\n",
1024 					(u_long)p->p_pid, signum);
1025 #endif
1026 				break;		/* == ignore */
1027 			}
1028 			/*
1029 			 * If there is a pending stop signal to process
1030 			 * with default action, stop here,
1031 			 * then clear the signal.  However,
1032 			 * if process is member of an orphaned
1033 			 * process group, ignore tty stop signals.
1034 			 */
1035 			if (prop & SA_STOP) {
1036 				if (p->p_flag & P_TRACED ||
1037 		    		    (p->p_pgrp->pg_jobc == 0 &&
1038 				    prop & SA_TTYSTOP))
1039 					break;	/* == ignore */
1040 				p->p_xstat = signum;
1041 				stop(p);
1042 				if ((p->p_pptr->p_flag & P_NOCLDSTOP) == 0)
1043 					psignal(p->p_pptr, SIGCHLD);
1044 				mi_switch();
1045 				break;
1046 			} else if (prop & SA_IGNORE) {
1047 				/*
1048 				 * Except for SIGCONT, shouldn't get here.
1049 				 * Default action is to ignore; drop it.
1050 				 */
1051 				break;		/* == ignore */
1052 			} else
1053 				return (signum);
1054 			/*NOTREACHED*/
1055 
1056 		case (int)SIG_IGN:
1057 			/*
1058 			 * Masking above should prevent us ever trying
1059 			 * to take action on an ignored signal other
1060 			 * than SIGCONT, unless process is traced.
1061 			 */
1062 			if ((prop & SA_CONT) == 0 &&
1063 			    (p->p_flag & P_TRACED) == 0)
1064 				printf("issignal\n");
1065 			break;		/* == ignore */
1066 
1067 		default:
1068 			/*
1069 			 * This signal has an action, let
1070 			 * postsig() process it.
1071 			 */
1072 			return (signum);
1073 		}
1074 		p->p_siglist &= ~mask;		/* take the signal! */
1075 	}
1076 	/* NOTREACHED */
1077 }
1078 
1079 /*
1080  * Put the argument process into the stopped state and notify the parent
1081  * via wakeup.  Signals are handled elsewhere.  The process must not be
1082  * on the run queue.
1083  */
1084 void
1085 stop(p)
1086 	register struct proc *p;
1087 {
1088 
1089 	p->p_stat = SSTOP;
1090 	p->p_flag &= ~P_WAITED;
1091 	wakeup((caddr_t)p->p_pptr);
1092 }
1093 
1094 /*
1095  * Take the action for the specified signal
1096  * from the current set of pending signals.
1097  */
1098 void
1099 postsig(signum)
1100 	register int signum;
1101 {
1102 	register struct proc *p = curproc;
1103 	register struct sigacts *ps = p->p_sigacts;
1104 	register sig_t action;
1105 	int code, mask, returnmask;
1106 
1107 #ifdef DIAGNOSTIC
1108 	if (signum == 0)
1109 		panic("postsig");
1110 #endif
1111 	mask = sigmask(signum);
1112 	p->p_siglist &= ~mask;
1113 	action = ps->ps_sigact[signum];
1114 #ifdef KTRACE
1115 	if (KTRPOINT(p, KTR_PSIG))
1116 		ktrpsig(p->p_tracep,
1117 		    signum, action, ps->ps_flags & SAS_OLDMASK ?
1118 		    ps->ps_oldmask : p->p_sigmask, 0);
1119 #endif
1120 	if (action == SIG_DFL) {
1121 		/*
1122 		 * Default action, where the default is to kill
1123 		 * the process.  (Other cases were ignored above.)
1124 		 */
1125 		sigexit(p, signum);
1126 		/* NOTREACHED */
1127 	} else {
1128 		/*
1129 		 * If we get here, the signal must be caught.
1130 		 */
1131 #ifdef DIAGNOSTIC
1132 		if (action == SIG_IGN || (p->p_sigmask & mask))
1133 			panic("postsig action");
1134 #endif
1135 		/*
1136 		 * Set the new mask value and also defer further
1137 		 * occurences of this signal.
1138 		 *
1139 		 * Special case: user has done a sigpause.  Here the
1140 		 * current mask is not of interest, but rather the
1141 		 * mask from before the sigpause is what we want
1142 		 * restored after the signal processing is completed.
1143 		 */
1144 		(void) splhigh();
1145 		if (ps->ps_flags & SAS_OLDMASK) {
1146 			returnmask = ps->ps_oldmask;
1147 			ps->ps_flags &= ~SAS_OLDMASK;
1148 		} else
1149 			returnmask = p->p_sigmask;
1150 		p->p_sigmask |= ps->ps_catchmask[signum] |
1151 				(mask & ~ps->ps_signodefer);
1152 		if ((ps->ps_sigreset & mask) != 0) {
1153 			/*
1154 			 * See setsigvec() for origin of this code.
1155 			 */
1156 			p->p_sigcatch &= ~mask;
1157 			if (signum != SIGCONT && sigprop[signum] & SA_IGNORE)
1158 				p->p_sigignore |= mask;
1159 			ps->ps_sigact[signum] = SIG_DFL;
1160 		}
1161 		(void) spl0();
1162 		p->p_stats->p_ru.ru_nsignals++;
1163 		if (ps->ps_sig != signum) {
1164 			code = 0;
1165 		} else {
1166 			code = ps->ps_code;
1167 			ps->ps_code = 0;
1168 			ps->ps_sig = 0;
1169 		}
1170 		(*p->p_sysent->sv_sendsig)(action, signum, returnmask, code);
1171 	}
1172 }
1173 
1174 /*
1175  * Kill the current process for stated reason.
1176  */
1177 void
1178 killproc(p, why)
1179 	struct proc *p;
1180 	char *why;
1181 {
1182 	log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n", p->p_pid, p->p_comm,
1183 		p->p_cred && p->p_ucred ? p->p_ucred->cr_uid : -1, why);
1184 	psignal(p, SIGKILL);
1185 }
1186 
1187 /*
1188  * Force the current process to exit with the specified signal, dumping core
1189  * if appropriate.  We bypass the normal tests for masked and caught signals,
1190  * allowing unrecoverable failures to terminate the process without changing
1191  * signal state.  Mark the accounting record with the signal termination.
1192  * If dumping core, save the signal number for the debugger.  Calls exit and
1193  * does not return.
1194  */
1195 void
1196 sigexit(p, signum)
1197 	register struct proc *p;
1198 	int signum;
1199 {
1200 
1201 	p->p_acflag |= AXSIG;
1202 	if (sigprop[signum] & SA_CORE) {
1203 		p->p_sigacts->ps_sig = signum;
1204 		/*
1205 		 * Log signals which would cause core dumps
1206 		 * (Log as LOG_INFO to appease those who don't want
1207 		 * these messages.)
1208 		 * XXX : Todo, as well as euid, write out ruid too
1209 		 */
1210 		if (coredump(p) == 0)
1211 			signum |= WCOREFLAG;
1212 		log(LOG_INFO, "pid %d (%s), uid %d: exited on signal %d%s\n",
1213 			p->p_pid, p->p_comm,
1214 			p->p_cred && p->p_ucred ? p->p_ucred->cr_uid : -1,
1215 			signum &~ WCOREFLAG,
1216 			signum & WCOREFLAG ? " (core dumped)" : "");
1217 	}
1218 	exit1(p, W_EXITCODE(0, signum));
1219 	/* NOTREACHED */
1220 }
1221 
1222 /*
1223  * Dump core, into a file named "progname.core", unless the process was
1224  * setuid/setgid.
1225  */
1226 static int
1227 coredump(p)
1228 	register struct proc *p;
1229 {
1230 	register struct vnode *vp;
1231 	register struct ucred *cred = p->p_cred->pc_ucred;
1232 	register struct vmspace *vm = p->p_vmspace;
1233 	struct nameidata nd;
1234 	struct vattr vattr;
1235 	int error, error1;
1236 	char name[MAXCOMLEN+6];		/* progname.core */
1237 
1238 	if (p->p_flag & P_SUGID)
1239 		return (EFAULT);
1240 	if (ctob(UPAGES + vm->vm_dsize + vm->vm_ssize) >=
1241 	    p->p_rlimit[RLIMIT_CORE].rlim_cur)
1242 		return (EFAULT);
1243 	sprintf(name, "%s.core", p->p_comm);
1244 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, name, p);
1245 	if ((error = vn_open(&nd,
1246 	    O_CREAT | FWRITE, S_IRUSR | S_IWUSR)))
1247 		return (error);
1248 	vp = nd.ni_vp;
1249 
1250 	/* Don't dump to non-regular files or files with links. */
1251 	if (vp->v_type != VREG ||
1252 	    VOP_GETATTR(vp, &vattr, cred, p) || vattr.va_nlink != 1) {
1253 		error = EFAULT;
1254 		goto out;
1255 	}
1256 	VATTR_NULL(&vattr);
1257 	vattr.va_size = 0;
1258 	VOP_LEASE(vp, p, cred, LEASE_WRITE);
1259 	VOP_SETATTR(vp, &vattr, cred, p);
1260 	p->p_acflag |= ACORE;
1261 	bcopy(p, &p->p_addr->u_kproc.kp_proc, sizeof(struct proc));
1262 	fill_eproc(p, &p->p_addr->u_kproc.kp_eproc);
1263 	error = cpu_coredump(p, vp, cred);
1264 	if (error == 0)
1265 		error = vn_rdwr(UIO_WRITE, vp, vm->vm_daddr,
1266 		    (int)ctob(vm->vm_dsize), (off_t)ctob(UPAGES), UIO_USERSPACE,
1267 		    IO_NODELOCKED|IO_UNIT, cred, (int *) NULL, p);
1268 	if (error == 0)
1269 		error = vn_rdwr(UIO_WRITE, vp,
1270 		    (caddr_t) trunc_page(USRSTACK - ctob(vm->vm_ssize)),
1271 		    round_page(ctob(vm->vm_ssize)),
1272 		    (off_t)ctob(UPAGES) + ctob(vm->vm_dsize), UIO_USERSPACE,
1273 		    IO_NODELOCKED|IO_UNIT, cred, (int *) NULL, p);
1274 out:
1275 	VOP_UNLOCK(vp, 0, p);
1276 	error1 = vn_close(vp, FWRITE, cred, p);
1277 	if (error == 0)
1278 		error = error1;
1279 	return (error);
1280 }
1281 
1282 /*
1283  * Nonexistent system call-- signal process (may want to handle it).
1284  * Flag error in case process won't see signal immediately (blocked or ignored).
1285  */
1286 #ifndef _SYS_SYSPROTO_H_
1287 struct nosys_args {
1288 	int	dummy;
1289 };
1290 #endif
1291 /* ARGSUSED */
1292 int
1293 nosys(p, args, retval)
1294 	struct proc *p;
1295 	struct nosys_args *args;
1296 	int *retval;
1297 {
1298 
1299 	psignal(p, SIGSYS);
1300 	return (EINVAL);
1301 }
1302