init.c revision 1.32 
1/*	$OpenBSD: init.c,v 1.32 2003/06/02 20:06:15 millert Exp $	*/
2/*	$NetBSD: init.c,v 1.22 1996/05/15 23:29:33 jtc Exp $	*/
3
4/*-
5 * Copyright (c) 1991, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Donn Seeley at Berkeley Software Design, Inc.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#ifndef lint
37static char copyright[] =
38"@(#) Copyright (c) 1991, 1993\n\
39	The Regents of the University of California.  All rights reserved.\n";
40#endif /* not lint */
41
42#ifndef lint
43#if 0
44static char sccsid[] = "@(#)init.c	8.2 (Berkeley) 4/28/95";
45#else
46static char rcsid[] = "$OpenBSD: init.c,v 1.32 2003/06/02 20:06:15 millert Exp $";
47#endif
48#endif /* not lint */
49
50#include <sys/param.h>
51#include <sys/sysctl.h>
52#include <sys/wait.h>
53#include <sys/reboot.h>
54
55#include <db.h>
56#include <errno.h>
57#include <fcntl.h>
58#include <signal.h>
59#include <stdarg.h>
60#include <stdio.h>
61#include <stdlib.h>
62#include <string.h>
63#include <syslog.h>
64#include <time.h>
65#include <ttyent.h>
66#include <unistd.h>
67#include <util.h>
68
69#ifdef SECURE
70#include <pwd.h>
71#endif
72
73#ifdef LOGIN_CAP
74#include <login_cap.h>
75#endif
76
77#include "pathnames.h"
78
79/*
80 * Sleep times; used to prevent thrashing.
81 */
82#define	GETTY_SPACING		 5	/* N secs minimum getty spacing */
83#define	GETTY_SLEEP		30	/* sleep N secs after spacing problem */
84#define	WINDOW_WAIT		 3	/* wait N secs after starting window */
85#define	STALL_TIMEOUT		30	/* wait N secs after warning */
86#define	DEATH_WATCH		10	/* wait N secs for procs to die */
87
88/*
89 * User-based resource limits.
90 */
91#define RESOURCE_RC		"daemon"
92#define RESOURCE_WINDOW		"default"
93#define RESOURCE_GETTY		"default"
94
95#ifndef DEFAULT_STATE
96#define DEFAULT_STATE		runcom
97#endif
98
99void handle(sig_t, ...);
100void delset(sigset_t *, ...);
101
102void stall(char *, ...);
103void warning(char *, ...);
104void emergency(char *, ...);
105void disaster(int);
106void badsys(int);
107
108/*
109 * We really need a recursive typedef...
110 * The following at least guarantees that the return type of (*state_t)()
111 * is sufficiently wide to hold a function pointer.
112 */
113typedef long (*state_func_t)(void);
114typedef state_func_t (*state_t)(void);
115
116state_func_t single_user(void);
117state_func_t runcom(void);
118state_func_t read_ttys(void);
119state_func_t multi_user(void);
120state_func_t clean_ttys(void);
121state_func_t catatonia(void);
122state_func_t death(void);
123state_func_t nice_death(void);
124
125enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;
126
127void transition(state_t);
128state_t requested_transition = DEFAULT_STATE;
129
130void setctty(char *);
131
132typedef struct init_session {
133	int	se_index;		/* index of entry in ttys file */
134	pid_t	se_process;		/* controlling process */
135	time_t	se_started;		/* used to avoid thrashing */
136	int	se_flags;		/* status of session */
137#define	SE_SHUTDOWN	0x1		/* session won't be restarted */
138#define	SE_PRESENT	0x2		/* session is in /etc/ttys */
139#define	SE_DEVEXISTS	0x4		/* open does not result in ENODEV */
140	char	*se_device;		/* filename of port */
141	char	*se_getty;		/* what to run on that port */
142	char	**se_getty_argv;	/* pre-parsed argument array */
143	char	*se_window;		/* window system (started only once) */
144	char	**se_window_argv;	/* pre-parsed argument array */
145	struct	init_session *se_prev;
146	struct	init_session *se_next;
147} session_t;
148
149void free_session(session_t *);
150session_t *new_session(session_t *, int, struct ttyent *);
151session_t *sessions;
152
153char **construct_argv(char *);
154void start_window_system(session_t *);
155void collect_child(pid_t);
156pid_t start_getty(session_t *);
157void transition_handler(int);
158void alrm_handler(int);
159void setsecuritylevel(int);
160int getsecuritylevel(void);
161int setupargv(session_t *, struct ttyent *);
162int clang;
163
164#ifdef LOGIN_CAP
165void setprocresources(char *);
166#else
167#define setprocresources(p)
168#endif
169
170void clear_session_logs(session_t *);
171
172int start_session_db(void);
173void add_session(session_t *);
174void del_session(session_t *);
175session_t *find_session(pid_t);
176DB *session_db;
177
178/*
179 * The mother of all processes.
180 */
181int
182main(int argc, char *argv[])
183{
184	int c;
185	struct sigaction sa;
186	sigset_t mask;
187
188	/* Dispose of random users. */
189	if (getuid() != 0) {
190		(void)fprintf(stderr, "init: %s\n", strerror(EPERM));
191		exit (1);
192	}
193
194	/* System V users like to reexec init. */
195	if (getpid() != 1) {
196		(void)fprintf(stderr, "init: already running\n");
197		exit (1);
198	}
199
200	/*
201	 * Note that this does NOT open a file...
202	 * Does 'init' deserve its own facility number?
203	 */
204	openlog("init", LOG_CONS|LOG_ODELAY, LOG_AUTH);
205
206	/*
207	 * Create an initial session.
208	 */
209	if (setsid() < 0)
210		warning("initial setsid() failed: %m");
211
212	/*
213	 * Establish an initial user so that programs running
214	 * single user do not freak out and die (like passwd).
215	 */
216	if (setlogin("root") < 0)
217		warning("setlogin() failed: %m");
218
219	/*
220	 * This code assumes that we always get arguments through flags,
221	 * never through bits set in some random machine register.
222	 */
223	while ((c = getopt(argc, argv, "sf")) != -1)
224		switch (c) {
225		case 's':
226			requested_transition = single_user;
227			break;
228		case 'f':
229			runcom_mode = FASTBOOT;
230			break;
231		default:
232			warning("unrecognized flag '-%c'", c);
233			break;
234		}
235
236	if (optind != argc)
237		warning("ignoring excess arguments");
238
239	/*
240	 * We catch or block signals rather than ignore them,
241	 * so that they get reset on exec.
242	 */
243	handle(badsys, SIGSYS, 0);
244	handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV,
245	       SIGBUS, SIGXCPU, SIGXFSZ, 0);
246	handle(transition_handler, SIGHUP, SIGTERM, SIGTSTP, SIGUSR1, 0);
247	handle(alrm_handler, SIGALRM, 0);
248	sigfillset(&mask);
249	delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
250		SIGXCPU, SIGXFSZ, SIGHUP, SIGTERM, SIGUSR1, SIGTSTP, SIGALRM, 0);
251	sigprocmask(SIG_SETMASK, &mask, NULL);
252	memset(&sa, 0, sizeof sa);
253	sigemptyset(&sa.sa_mask);
254	sa.sa_flags = 0;
255	sa.sa_handler = SIG_IGN;
256	(void) sigaction(SIGTTIN, &sa, NULL);
257	(void) sigaction(SIGTTOU, &sa, NULL);
258
259	/*
260	 * Paranoia.
261	 */
262	close(STDIN_FILENO);
263	close(STDOUT_FILENO);
264	close(STDERR_FILENO);
265
266	/*
267	 * Start the state machine.
268	 */
269	transition(requested_transition);
270
271	/*
272	 * Should never reach here.
273	 */
274	exit(1);
275}
276
277/*
278 * Associate a function with a signal handler.
279 */
280void
281handle(sig_t handler, ...)
282{
283	int sig;
284	struct sigaction sa;
285	sigset_t mask_everything;
286	va_list ap;
287
288	va_start(ap, handler);
289
290	memset(&sa, 0, sizeof sa);
291	sa.sa_handler = handler;
292	sigfillset(&mask_everything);
293
294	while ((sig = va_arg(ap, int))) {
295		sa.sa_mask = mask_everything;
296		/* XXX SA_RESTART? */
297		sa.sa_flags = sig == SIGCHLD ? SA_NOCLDSTOP : 0;
298		sigaction(sig, &sa, NULL);
299	}
300	va_end(ap);
301}
302
303/*
304 * Delete a set of signals from a mask.
305 */
306void
307delset(sigset_t *maskp, ...)
308{
309	int sig;
310	va_list ap;
311
312	va_start(ap, maskp);
313	while ((sig = va_arg(ap, int)))
314		sigdelset(maskp, sig);
315	va_end(ap);
316}
317
318/*
319 * Log a message and sleep for a while (to give someone an opportunity
320 * to read it and to save log or hardcopy output if the problem is chronic).
321 * NB: should send a message to the session logger to avoid blocking.
322 */
323void
324stall(char *message, ...)
325{
326	va_list ap;
327
328	va_start(ap, message);
329	vsyslog(LOG_ALERT, message, ap);
330	va_end(ap);
331	closelog();
332	sleep(STALL_TIMEOUT);
333}
334
335/*
336 * Like stall(), but doesn't sleep.
337 * If cpp had variadic macros, the two functions could be #defines for another.
338 * NB: should send a message to the session logger to avoid blocking.
339 */
340void
341warning(char *message, ...)
342{
343	va_list ap;
344
345	va_start(ap, message);
346	vsyslog(LOG_ALERT, message, ap);
347	va_end(ap);
348	closelog();
349}
350
351/*
352 * Log an emergency message.
353 * NB: should send a message to the session logger to avoid blocking.
354 */
355void
356emergency(char *message, ...)
357{
358	struct syslog_data sdata = SYSLOG_DATA_INIT;
359	va_list ap;
360
361	va_start(ap, message);
362	vsyslog_r(LOG_EMERG, &sdata, message, ap);
363	va_end(ap);
364}
365
366/*
367 * Catch a SIGSYS signal.
368 *
369 * These may arise if a system does not support sysctl.
370 * We tolerate up to 25 of these, then throw in the towel.
371 */
372void
373badsys(int sig)
374{
375	static int badcount = 0;
376
377	if (badcount++ < 25)
378		return;
379	disaster(sig);
380}
381
382/*
383 * Catch an unexpected signal.
384 */
385void
386disaster(int sig)
387{
388	emergency("fatal signal: %s", strsignal(sig));
389
390	sleep(STALL_TIMEOUT);
391	_exit(sig);		/* reboot */
392}
393
394/*
395 * Get the security level of the kernel.
396 */
397int
398getsecuritylevel(void)
399{
400#ifdef KERN_SECURELVL
401	int name[2], curlevel;
402	size_t len;
403
404	name[0] = CTL_KERN;
405	name[1] = KERN_SECURELVL;
406	len = sizeof curlevel;
407	if (sysctl(name, 2, &curlevel, &len, NULL, 0) == -1) {
408		emergency("cannot get kernel security level: %s",
409		    strerror(errno));
410		return (-1);
411	}
412	return (curlevel);
413#else
414	return (-1);
415#endif
416}
417
418/*
419 * Set the security level of the kernel.
420 */
421void
422setsecuritylevel(int newlevel)
423{
424#ifdef KERN_SECURELVL
425	int name[2], curlevel;
426	extern int errno;
427
428	curlevel = getsecuritylevel();
429	if (newlevel == curlevel)
430		return;
431	name[0] = CTL_KERN;
432	name[1] = KERN_SECURELVL;
433	if (sysctl(name, 2, NULL, NULL, &newlevel, sizeof newlevel) == -1) {
434		emergency(
435		    "cannot change kernel security level from %d to %d: %s",
436		    curlevel, newlevel, strerror(errno));
437		return;
438	}
439#ifdef SECURE
440	warning("kernel security level changed from %d to %d",
441	    curlevel, newlevel);
442#endif
443#endif
444}
445
446/*
447 * Change states in the finite state machine.
448 * The initial state is passed as an argument.
449 */
450void
451transition(state_t s)
452{
453	for (;;)
454		s = (state_t) (*s)();
455}
456
457/*
458 * Close out the accounting files for a login session.
459 * NB: should send a message to the session logger to avoid blocking.
460 */
461void
462clear_session_logs(session_t *sp)
463{
464	char *line = sp->se_device + sizeof(_PATH_DEV) - 1;
465
466	if (logout(line))
467		logwtmp(line, "", "");
468}
469
470/*
471 * Start a session and allocate a controlling terminal.
472 * Only called by children of init after forking.
473 */
474void
475setctty(char *name)
476{
477	int fd;
478
479	(void) revoke(name);
480	sleep(2);			/* leave DTR low */
481	if ((fd = open(name, O_RDWR)) == -1) {
482		stall("can't open %s: %m", name);
483		_exit(1);
484	}
485	if (login_tty(fd) == -1) {
486		stall("can't get %s for controlling terminal: %m", name);
487		_exit(1);
488	}
489}
490
491/*
492 * Bring the system up single user.
493 */
494state_func_t
495single_user(void)
496{
497	pid_t pid, wpid;
498	int status;
499	sigset_t mask;
500	char shell[MAXPATHLEN];		/* Allocate space here */
501	char name[MAXPATHLEN];		/* Name (argv[0]) of shell */
502	char *argv[2];
503#ifdef SECURE
504	struct ttyent *typ;
505	struct passwd *pp;
506	static const char banner[] =
507		"Enter root password, or ^D to go multi-user\n";
508	char *clear, *password;
509#endif
510
511	/* Init shell and name */
512	strlcpy(shell, _PATH_BSHELL, sizeof shell);
513	strlcpy(name, "-sh", sizeof name);
514
515	/*
516	 * If the kernel is in secure mode, downgrade it to insecure mode.
517	 */
518	if (getsecuritylevel() > 0)
519		setsecuritylevel(0);
520
521	if ((pid = fork()) == 0) {
522		/*
523		 * Start the single user session.
524		 */
525		setctty(_PATH_CONSOLE);
526
527#ifdef SECURE
528		/*
529		 * Check the root password.
530		 * We don't care if the console is 'on' by default;
531		 * it's the only tty that can be 'off' and 'secure'.
532		 */
533		typ = getttynam("console");
534		pp = getpwnam("root");
535		if (typ && (typ->ty_status & TTY_SECURE) == 0 && pp &&
536		    *pp->pw_passwd) {
537			write(STDERR_FILENO, banner, sizeof banner - 1);
538			for (;;) {
539				clear = getpass("Password:");
540				if (clear == 0 || *clear == '\0')
541					_exit(0);
542				password = crypt(clear, pp->pw_passwd);
543				memset(clear, 0, _PASSWORD_LEN);
544				if (strcmp(password, pp->pw_passwd) == 0)
545					break;
546				warning("single-user login failed\n");
547			}
548		}
549		endttyent();
550		endpwent();
551#endif /* SECURE */
552
553#ifdef DEBUGSHELL
554		{
555			char altshell[128], *cp = altshell;
556			int num;
557
558#define	SHREQUEST \
559	"Enter pathname of shell or RETURN for sh: "
560
561			(void)write(STDERR_FILENO,
562			    SHREQUEST, sizeof(SHREQUEST) - 1);
563			while ((num = read(STDIN_FILENO, cp, 1)) != -1 &&
564			    num != 0 && *cp != '\n' && cp < &altshell[127])
565				cp++;
566			*cp = '\0';
567
568			/* Copy in alternate shell */
569			if (altshell[0] != '\0'){
570				char *p;
571
572				/* Binary to exec */
573				strlcpy(shell, altshell, sizeof shell);
574
575				/* argv[0] */
576				p = strrchr(altshell, '/');
577				if(p == NULL) p = altshell;
578				else p++;
579
580				name[0] = '-';
581				strlcpy(&name[1], p, sizeof name -1);
582			}
583		}
584#endif /* DEBUGSHELL */
585
586		/*
587		 * Unblock signals.
588		 * We catch all the interesting ones,
589		 * and those are reset to SIG_DFL on exec.
590		 */
591		sigemptyset(&mask);
592		sigprocmask(SIG_SETMASK, &mask, NULL);
593
594		/*
595		 * Fire off a shell.
596		 * If the default one doesn't work, try the Bourne shell.
597		 */
598		argv[0] = name;
599		argv[1] = NULL;
600		setenv("PATH", _PATH_STDPATH, 1);
601		execv(shell, argv);
602		emergency("can't exec %s for single user: %m", shell);
603
604		argv[0] = "-sh";
605		argv[1] = NULL;
606		execv(_PATH_BSHELL, argv);
607		emergency("can't exec %s for single user: %m", _PATH_BSHELL);
608		sleep(STALL_TIMEOUT);
609		_exit(1);
610	}
611
612	if (pid == -1) {
613		/*
614		 * We are seriously hosed.  Do our best.
615		 */
616		emergency("can't fork single-user shell, trying again");
617		while (waitpid(-1, NULL, WNOHANG) > 0)
618			continue;
619		return (state_func_t) single_user;
620	}
621
622	requested_transition = 0;
623	do {
624		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
625			collect_child(wpid);
626		if (wpid == -1) {
627			if (errno == EINTR)
628				continue;
629			warning("wait for single-user shell failed: %m; restarting");
630			return (state_func_t) single_user;
631		}
632		if (wpid == pid && WIFSTOPPED(status)) {
633			warning("init: shell stopped, restarting\n");
634			kill(pid, SIGCONT);
635			wpid = -1;
636		}
637	} while (wpid != pid && !requested_transition);
638
639	if (requested_transition)
640		return (state_func_t) requested_transition;
641
642	if (!WIFEXITED(status)) {
643		if (WTERMSIG(status) == SIGKILL) {
644			/*
645			 *  reboot(8) killed shell?
646			 */
647			warning("single user shell terminated.");
648			sleep(STALL_TIMEOUT);
649			_exit(0);
650		} else {
651			warning("single user shell terminated, restarting");
652			return (state_func_t) single_user;
653		}
654	}
655
656	runcom_mode = FASTBOOT;
657	return (state_func_t) runcom;
658}
659
660/*
661 * Run the system startup script.
662 */
663state_func_t
664runcom(void)
665{
666	pid_t pid, wpid;
667	int status;
668	char *argv[4];
669	struct sigaction sa;
670
671	if ((pid = fork()) == 0) {
672		memset(&sa, 0, sizeof sa);
673		sigemptyset(&sa.sa_mask);
674		sa.sa_flags = 0;
675		sa.sa_handler = SIG_IGN;
676		(void) sigaction(SIGTSTP, &sa, NULL);
677		(void) sigaction(SIGHUP, &sa, NULL);
678
679		setctty(_PATH_CONSOLE);
680
681		argv[0] = "sh";
682		argv[1] = _PATH_RUNCOM;
683		argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : 0;
684		argv[3] = 0;
685
686		sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
687
688		setprocresources(RESOURCE_RC);
689
690		execv(_PATH_BSHELL, argv);
691		stall("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNCOM);
692		_exit(1);	/* force single user mode */
693	}
694
695	if (pid == -1) {
696		emergency("can't fork for %s on %s: %m",
697			_PATH_BSHELL, _PATH_RUNCOM);
698		while (waitpid(-1, NULL, WNOHANG) > 0)
699			continue;
700		sleep(STALL_TIMEOUT);
701		return (state_func_t) single_user;
702	}
703
704	/*
705	 * Copied from single_user().  This is a bit paranoid.
706	 */
707	do {
708		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
709			collect_child(wpid);
710		if (wpid == -1) {
711			if (errno == EINTR)
712				continue;
713			warning("wait for %s on %s failed: %m; going to single user mode",
714				_PATH_BSHELL, _PATH_RUNCOM);
715			return (state_func_t) single_user;
716		}
717		if (wpid == pid && WIFSTOPPED(status)) {
718			warning("init: %s on %s stopped, restarting\n",
719				_PATH_BSHELL, _PATH_RUNCOM);
720			kill(pid, SIGCONT);
721			wpid = -1;
722		}
723	} while (wpid != pid);
724
725	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
726	    requested_transition == catatonia) {
727		/* /etc/rc executed /sbin/reboot; wait for the end quietly */
728		sigset_t s;
729
730		sigfillset(&s);
731		for (;;)
732			sigsuspend(&s);
733	}
734
735	if (!WIFEXITED(status)) {
736		warning("%s on %s terminated abnormally, going to single user mode",
737			_PATH_BSHELL, _PATH_RUNCOM);
738		return (state_func_t) single_user;
739	}
740
741	if (WEXITSTATUS(status))
742		return (state_func_t) single_user;
743
744	runcom_mode = AUTOBOOT;		/* the default */
745	/* NB: should send a message to the session logger to avoid blocking. */
746	logwtmp("~", "reboot", "");
747	return (state_func_t) read_ttys;
748}
749
750/*
751 * Open the session database.
752 *
753 * NB: We could pass in the size here; is it necessary?
754 */
755int
756start_session_db(void)
757{
758	if (session_db && (*session_db->close)(session_db))
759		emergency("session database close: %s", strerror(errno));
760	if ((session_db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == 0) {
761		emergency("session database open: %s", strerror(errno));
762		return (1);
763	}
764	return (0);
765}
766
767/*
768 * Add a new login session.
769 */
770void
771add_session(session_t *sp)
772{
773	DBT key;
774	DBT data;
775
776	key.data = &sp->se_process;
777	key.size = sizeof sp->se_process;
778	data.data = &sp;
779	data.size = sizeof sp;
780
781	if ((*session_db->put)(session_db, &key, &data, 0))
782		emergency("insert %d: %s", sp->se_process, strerror(errno));
783}
784
785/*
786 * Delete an old login session.
787 */
788void
789del_session(session_t *sp)
790{
791	DBT key;
792
793	key.data = &sp->se_process;
794	key.size = sizeof sp->se_process;
795
796	if ((*session_db->del)(session_db, &key, 0))
797		emergency("delete %d: %s", sp->se_process, strerror(errno));
798}
799
800/*
801 * Look up a login session by pid.
802 */
803session_t *
804find_session(pid_t pid)
805{
806	DBT key;
807	DBT data;
808	session_t *ret;
809
810	key.data = &pid;
811	key.size = sizeof pid;
812	if ((*session_db->get)(session_db, &key, &data, 0) != 0)
813		return (0);
814	memcpy(&ret, data.data, sizeof(ret));
815	return (ret);
816}
817
818/*
819 * Construct an argument vector from a command line.
820 */
821char **
822construct_argv(char *command)
823{
824	int argc = 0;
825	char **argv = (char **) malloc(((strlen(command) + 1) / 2 + 1)
826						* sizeof (char *));
827	static const char separators[] = " \t";
828
829	if ((argv[argc++] = strtok(command, separators)) == 0)
830		return (0);
831	while ((argv[argc++] = strtok(NULL, separators)))
832		continue;
833	return (argv);
834}
835
836/*
837 * Deallocate a session descriptor.
838 */
839void
840free_session(session_t *sp)
841{
842	free(sp->se_device);
843	if (sp->se_getty) {
844		free(sp->se_getty);
845		free(sp->se_getty_argv);
846	}
847	if (sp->se_window) {
848		free(sp->se_window);
849		free(sp->se_window_argv);
850	}
851	free(sp);
852}
853
854/*
855 * Allocate a new session descriptor.
856 */
857session_t *
858new_session(session_t *sprev, int session_index, struct ttyent *typ)
859{
860	session_t *sp;
861	size_t len;
862
863	if ((typ->ty_status & TTY_ON) == 0 ||
864	    typ->ty_name == 0 ||
865	    typ->ty_getty == 0)
866		return (0);
867
868	sp = (session_t *) malloc(sizeof (session_t));
869	memset(sp, 0, sizeof *sp);
870
871	sp->se_flags = SE_PRESENT;
872	sp->se_index = session_index;
873
874	len = sizeof(_PATH_DEV) + strlen(typ->ty_name);
875	sp->se_device = malloc(len);
876	(void) snprintf(sp->se_device, len, "%s%s", _PATH_DEV, typ->ty_name);
877
878	if (setupargv(sp, typ) == 0) {
879		free_session(sp);
880		return (0);
881	}
882
883	sp->se_next = 0;
884	if (sprev == 0) {
885		sessions = sp;
886		sp->se_prev = 0;
887	} else {
888		sprev->se_next = sp;
889		sp->se_prev = sprev;
890	}
891
892	return (sp);
893}
894
895/*
896 * Calculate getty and if useful window argv vectors.
897 */
898int
899setupargv(session_t *sp, struct ttyent *typ)
900{
901	size_t len;
902
903	if (sp->se_getty) {
904		free(sp->se_getty);
905		free(sp->se_getty_argv);
906	}
907	len = strlen(typ->ty_getty) + strlen(typ->ty_name) + 2;
908	sp->se_getty = malloc(len);
909	(void) snprintf(sp->se_getty, len, "%s %s", typ->ty_getty, typ->ty_name);
910	sp->se_getty_argv = construct_argv(sp->se_getty);
911	if (sp->se_getty_argv == 0) {
912		warning("can't parse getty for port %s", sp->se_device);
913		free(sp->se_getty);
914		sp->se_getty = 0;
915		return (0);
916	}
917	if (typ->ty_window) {
918		if (sp->se_window)
919			free(sp->se_window);
920		sp->se_window = strdup(typ->ty_window);
921		sp->se_window_argv = construct_argv(sp->se_window);
922		if (sp->se_window_argv == 0) {
923			warning("can't parse window for port %s",
924				sp->se_device);
925			free(sp->se_window);
926			sp->se_window = 0;
927			return (0);
928		}
929	}
930	return (1);
931}
932
933/*
934 * Walk the list of ttys and create sessions for each active line.
935 */
936state_func_t
937read_ttys(void)
938{
939	int session_index = 0;
940	session_t *sp, *snext;
941	struct ttyent *typ;
942
943	/*
944	 * Destroy any previous session state.
945	 * There shouldn't be any, but just in case...
946	 */
947	for (sp = sessions; sp; sp = snext) {
948		if (sp->se_process)
949			clear_session_logs(sp);
950		snext = sp->se_next;
951		free_session(sp);
952	}
953	sessions = 0;
954	if (start_session_db())
955		return (state_func_t) single_user;
956
957	/*
958	 * Allocate a session entry for each active port.
959	 * Note that sp starts at 0.
960	 */
961	while ((typ = getttyent()))
962		if ((snext = new_session(sp, ++session_index, typ)))
963			sp = snext;
964
965	endttyent();
966
967	return (state_func_t) multi_user;
968}
969
970/*
971 * Start a window system running.
972 */
973void
974start_window_system(session_t *sp)
975{
976	pid_t pid;
977	sigset_t mask;
978
979	if ((pid = fork()) == -1) {
980		emergency("can't fork for window system on port %s: %m",
981			sp->se_device);
982		/* hope that getty fails and we can try again */
983		return;
984	}
985
986	if (pid)
987		return;
988
989	sigemptyset(&mask);
990	sigprocmask(SIG_SETMASK, &mask, NULL);
991
992	if (setsid() < 0)
993		emergency("setsid failed (window) %m");
994
995	setprocresources(RESOURCE_WINDOW);
996
997	execv(sp->se_window_argv[0], sp->se_window_argv);
998	stall("can't exec window system '%s' for port %s: %m",
999		sp->se_window_argv[0], sp->se_device);
1000	_exit(1);
1001}
1002
1003/*
1004 * Start a login session running.
1005 * For first open, man-handle tty directly to determine if it
1006 * really exists. It is not efficient to spawn gettys on devices
1007 * that do not exist.
1008 */
1009pid_t
1010start_getty(session_t *sp)
1011{
1012	pid_t pid;
1013	sigset_t mask;
1014	time_t current_time = time(NULL);
1015	int p[2], new = 1;
1016
1017	if (sp->se_flags & SE_DEVEXISTS)
1018		new = 0;
1019
1020	if (new) {
1021		if (pipe(p) == -1)
1022			return (-1);
1023	}
1024
1025	/*
1026	 * fork(), not vfork() -- we can't afford to block.
1027	 */
1028	if ((pid = fork()) == -1) {
1029		emergency("can't fork for getty on port %s: %m", sp->se_device);
1030		return (-1);
1031	}
1032
1033	if (pid) {
1034		if (new) {
1035			char c;
1036
1037			close(p[1]);
1038			if (read(p[0], &c, 1) != 1) {
1039				close(p[0]);
1040				return (-1);
1041			}
1042			close(p[0]);
1043			if (c == '1')
1044				sp->se_flags |= SE_DEVEXISTS;
1045			else
1046				sp->se_flags |= SE_SHUTDOWN;
1047		}
1048		return (pid);
1049	}
1050	if (new) {
1051		int fd;
1052
1053		close(p[0]);
1054		fd = open(sp->se_device, O_RDONLY | O_NONBLOCK, 0666);
1055		if (fd == -1 && (errno == ENXIO || errno == ENOENT ||
1056		    errno == EISDIR)) {
1057			(void)write(p[1], "0", 1);
1058			close(p[1]);
1059			_exit(1);
1060		}
1061		(void)write(p[1], "1", 1);
1062		close(p[1]);
1063		close(fd);
1064		sleep(1);
1065	}
1066
1067	if (current_time > sp->se_started &&
1068	    current_time - sp->se_started < GETTY_SPACING) {
1069		warning("getty repeating too quickly on port %s, sleeping",
1070		        sp->se_device);
1071		sleep((unsigned) GETTY_SLEEP);
1072	}
1073
1074	if (sp->se_window) {
1075		start_window_system(sp);
1076		sleep(WINDOW_WAIT);
1077	}
1078
1079	sigemptyset(&mask);
1080	sigprocmask(SIG_SETMASK, &mask, NULL);
1081
1082	setprocresources(RESOURCE_GETTY);
1083
1084	execv(sp->se_getty_argv[0], sp->se_getty_argv);
1085	stall("can't exec getty '%s' for port %s: %m",
1086		sp->se_getty_argv[0], sp->se_device);
1087	_exit(1);
1088}
1089
1090/*
1091 * Collect exit status for a child.
1092 * If an exiting login, start a new login running.
1093 */
1094void
1095collect_child(pid_t pid)
1096{
1097	session_t *sp, *sprev, *snext;
1098
1099	if (sessions == NULL)
1100		return;
1101
1102	if ((sp = find_session(pid)) == NULL)
1103		return;
1104
1105	clear_session_logs(sp);
1106	login_fbtab(sp->se_device + sizeof(_PATH_DEV) - 1, 0, 0);
1107	del_session(sp);
1108	sp->se_process = 0;
1109
1110	if (sp->se_flags & SE_SHUTDOWN) {
1111		if ((sprev = sp->se_prev))
1112			sprev->se_next = sp->se_next;
1113		else
1114			sessions = sp->se_next;
1115		if ((snext = sp->se_next))
1116			snext->se_prev = sp->se_prev;
1117		free_session(sp);
1118		return;
1119	}
1120
1121	if ((pid = start_getty(sp)) == -1) {
1122		/* serious trouble */
1123		requested_transition = clean_ttys;
1124		return;
1125	}
1126
1127	sp->se_process = pid;
1128	sp->se_started = time(NULL);
1129	add_session(sp);
1130}
1131
1132/*
1133 * Catch a signal and request a state transition.
1134 */
1135void
1136transition_handler(int sig)
1137{
1138
1139	switch (sig) {
1140	case SIGHUP:
1141		requested_transition = clean_ttys;
1142		break;
1143	case SIGTERM:
1144		requested_transition = death;
1145		break;
1146	case SIGUSR1:
1147		requested_transition = nice_death;
1148		break;
1149	case SIGTSTP:
1150		requested_transition = catatonia;
1151		break;
1152	default:
1153		requested_transition = 0;
1154		break;
1155	}
1156}
1157
1158/*
1159 * Take the system multiuser.
1160 */
1161state_func_t
1162multi_user(void)
1163{
1164	pid_t pid;
1165	session_t *sp;
1166
1167	requested_transition = 0;
1168
1169	/*
1170	 * If the administrator has not set the security level to -1
1171	 * to indicate that the kernel should not run multiuser in secure
1172	 * mode, and the run script has not set a higher level of security
1173	 * than level 1, then put the kernel into secure mode.
1174	 */
1175	if (getsecuritylevel() == 0)
1176		setsecuritylevel(1);
1177
1178	for (sp = sessions; sp; sp = sp->se_next) {
1179		if (sp->se_process)
1180			continue;
1181		if ((pid = start_getty(sp)) == -1) {
1182			/* serious trouble */
1183			requested_transition = clean_ttys;
1184			break;
1185		}
1186		sp->se_process = pid;
1187		sp->se_started = time(NULL);
1188		add_session(sp);
1189	}
1190
1191	while (!requested_transition)
1192		if ((pid = waitpid(-1, NULL, 0)) != -1)
1193			collect_child(pid);
1194
1195	return (state_func_t) requested_transition;
1196}
1197
1198/*
1199 * This is an n-squared algorithm.  We hope it isn't run often...
1200 */
1201state_func_t
1202clean_ttys(void)
1203{
1204	session_t *sp, *sprev;
1205	struct ttyent *typ;
1206	int session_index = 0;
1207	int devlen;
1208
1209	for (sp = sessions; sp; sp = sp->se_next)
1210		sp->se_flags &= ~SE_PRESENT;
1211
1212	devlen = sizeof(_PATH_DEV) - 1;
1213	while ((typ = getttyent())) {
1214		++session_index;
1215
1216		for (sprev = 0, sp = sessions; sp; sprev = sp, sp = sp->se_next)
1217			if (strcmp(typ->ty_name, sp->se_device + devlen) == 0)
1218				break;
1219
1220		if (sp) {
1221			sp->se_flags |= SE_PRESENT;
1222			if (sp->se_index != session_index) {
1223				warning("port %s changed utmp index from %d to %d",
1224				       sp->se_device, sp->se_index,
1225				       session_index);
1226				sp->se_index = session_index;
1227			}
1228			if ((typ->ty_status & TTY_ON) == 0 ||
1229			    typ->ty_getty == 0) {
1230				sp->se_flags |= SE_SHUTDOWN;
1231				kill(sp->se_process, SIGHUP);
1232				continue;
1233			}
1234			sp->se_flags &= ~SE_SHUTDOWN;
1235			if (setupargv(sp, typ) == 0) {
1236				warning("can't parse getty for port %s",
1237					sp->se_device);
1238				sp->se_flags |= SE_SHUTDOWN;
1239				kill(sp->se_process, SIGHUP);
1240			}
1241			continue;
1242		}
1243
1244		new_session(sprev, session_index, typ);
1245	}
1246
1247	endttyent();
1248
1249	for (sp = sessions; sp; sp = sp->se_next)
1250		if ((sp->se_flags & SE_PRESENT) == 0) {
1251			sp->se_flags |= SE_SHUTDOWN;
1252			kill(sp->se_process, SIGHUP);
1253		}
1254
1255	return (state_func_t) multi_user;
1256}
1257
1258/*
1259 * Block further logins.
1260 */
1261state_func_t
1262catatonia(void)
1263{
1264	session_t *sp;
1265
1266	for (sp = sessions; sp; sp = sp->se_next)
1267		sp->se_flags |= SE_SHUTDOWN;
1268
1269	return (state_func_t) multi_user;
1270}
1271
1272/*
1273 * Note SIGALRM.
1274 */
1275void
1276alrm_handler(int sig)
1277{
1278	clang = 1;
1279}
1280
1281/*
1282 * Bring the system down to single user nicely, after run the shutdown script.
1283 */
1284state_func_t
1285nice_death(void)
1286{
1287	session_t *sp;
1288	int i;
1289	pid_t pid;
1290	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1291	int howto = RB_HALT;
1292	int status;
1293
1294	for (sp = sessions; sp; sp = sp->se_next) {
1295		sp->se_flags &= ~SE_PRESENT;
1296		sp->se_flags |= SE_SHUTDOWN;
1297		kill(sp->se_process, SIGHUP);
1298	}
1299
1300	/* NB: should send a message to the session logger to avoid blocking. */
1301	logwtmp("~", "shutdown", "");
1302
1303	if (access(_PATH_RUNCOM, R_OK) != -1) {
1304		pid_t pid;
1305		struct sigaction sa;
1306
1307		switch ((pid = fork())) {
1308		case -1:
1309			break;
1310		case 0:
1311
1312			memset(&sa, 0, sizeof sa);
1313			sigemptyset(&sa.sa_mask);
1314			sa.sa_flags = 0;
1315			sa.sa_handler = SIG_IGN;
1316			(void) sigaction(SIGTSTP, &sa, NULL);
1317			(void) sigaction(SIGHUP, &sa, NULL);
1318
1319			setctty(_PATH_CONSOLE);
1320
1321			sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
1322
1323			execl(_PATH_BSHELL, "sh", _PATH_RUNCOM, "shutdown",
1324			    (char *)NULL);
1325			stall("can't exec %s for %s %s: %m", _PATH_BSHELL,
1326			    _PATH_RUNCOM, "shutdown");
1327			_exit(1);
1328		default:
1329			waitpid(pid, &status, 0);
1330			if (WIFEXITED(status) && WEXITSTATUS(status) == 2)
1331				howto |= RB_POWERDOWN;
1332		}
1333	}
1334
1335	for (i = 0; i < 3; ++i) {
1336		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1337			goto die;
1338
1339		clang = 0;
1340		alarm(DEATH_WATCH);
1341		do
1342			if ((pid = waitpid(-1, NULL, 0)) != -1)
1343				collect_child(pid);
1344		while (clang == 0 && errno != ECHILD);
1345
1346		if (errno == ECHILD)
1347			goto die;
1348	}
1349
1350	warning("some processes would not die; ps axl advised");
1351
1352die:
1353	reboot(howto);
1354
1355	/* ... and if that fails.. oh well */
1356	return (state_func_t) single_user;
1357}
1358
1359/*
1360 * Bring the system down to single user.
1361 */
1362state_func_t
1363death(void)
1364{
1365	session_t *sp;
1366	int i;
1367	pid_t pid;
1368	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1369
1370	for (sp = sessions; sp; sp = sp->se_next)
1371		sp->se_flags |= SE_SHUTDOWN;
1372
1373	/* NB: should send a message to the session logger to avoid blocking. */
1374	logwtmp("~", "shutdown", "");
1375
1376	for (i = 0; i < 3; ++i) {
1377		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1378			return (state_func_t) single_user;
1379
1380		clang = 0;
1381		alarm(DEATH_WATCH);
1382		do
1383			if ((pid = waitpid(-1, NULL, 0)) != -1)
1384				collect_child(pid);
1385		while (clang == 0 && errno != ECHILD);
1386
1387		if (errno == ECHILD)
1388			return (state_func_t) single_user;
1389	}
1390
1391	warning("some processes would not die; ps axl advised");
1392
1393	return (state_func_t) single_user;
1394}
1395
1396#ifdef LOGIN_CAP
1397void
1398setprocresources(char *class)
1399{
1400	login_cap_t *lc;
1401
1402	if ((lc = login_getclass(class)) != NULL) {
1403		setusercontext(lc, NULL, 0,
1404		    LOGIN_SETPRIORITY|LOGIN_SETRESOURCES|LOGIN_SETUMASK);
1405		login_close(lc);
1406	}
1407}
1408#endif
1409