init.c revision 1.39 
1/*	$OpenBSD: init.c,v 1.39 2006/06/22 00:25:22 deraadt 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 1.39 2006/06/22 00:25:22 deraadt 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 hard_death(void);
124state_func_t nice_death(void);
125
126enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;
127
128void transition(state_t);
129state_t requested_transition = DEFAULT_STATE;
130
131void setctty(char *);
132
133typedef struct init_session {
134	int	se_index;		/* index of entry in ttys file */
135	pid_t	se_process;		/* controlling process */
136	time_t	se_started;		/* used to avoid thrashing */
137	int	se_flags;		/* status of session */
138#define	SE_SHUTDOWN	0x1		/* session won't be restarted */
139#define	SE_PRESENT	0x2		/* session is in /etc/ttys */
140#define	SE_DEVEXISTS	0x4		/* open does not result in ENODEV */
141	char	*se_device;		/* filename of port */
142	char	*se_getty;		/* what to run on that port */
143	char	**se_getty_argv;	/* pre-parsed argument array */
144	char	*se_window;		/* window system (started only once) */
145	char	**se_window_argv;	/* pre-parsed argument array */
146	struct	init_session *se_prev;
147	struct	init_session *se_next;
148} session_t;
149
150void free_session(session_t *);
151session_t *new_session(session_t *, int, struct ttyent *);
152session_t *sessions;
153
154char **construct_argv(char *);
155void start_window_system(session_t *);
156void collect_child(pid_t);
157pid_t start_getty(session_t *);
158void transition_handler(int);
159void alrm_handler(int);
160void setsecuritylevel(int);
161int getsecuritylevel(void);
162int setupargv(session_t *, struct ttyent *);
163int clang;
164
165#ifdef LOGIN_CAP
166void setprocresources(char *);
167#else
168#define setprocresources(p)
169#endif
170
171void clear_session_logs(session_t *);
172
173int start_session_db(void);
174void add_session(session_t *);
175void del_session(session_t *);
176session_t *find_session(pid_t);
177DB *session_db;
178
179/*
180 * The mother of all processes.
181 */
182int
183main(int argc, char *argv[])
184{
185	int c;
186	struct sigaction sa;
187	sigset_t mask;
188
189	/* Dispose of random users. */
190	if (getuid() != 0) {
191		(void)fprintf(stderr, "init: %s\n", strerror(EPERM));
192		exit (1);
193	}
194
195	/* System V users like to reexec init. */
196	if (getpid() != 1) {
197		(void)fprintf(stderr, "init: already running\n");
198		exit (1);
199	}
200
201	/*
202	 * Note that this does NOT open a file...
203	 * Does 'init' deserve its own facility number?
204	 */
205	openlog("init", LOG_CONS|LOG_ODELAY, LOG_AUTH);
206
207	/*
208	 * Create an initial session.
209	 */
210	if (setsid() < 0)
211		warning("initial setsid() failed: %m");
212
213	/*
214	 * Establish an initial user so that programs running
215	 * single user do not freak out and die (like passwd).
216	 */
217	if (setlogin("root") < 0)
218		warning("setlogin() failed: %m");
219
220	/*
221	 * This code assumes that we always get arguments through flags,
222	 * never through bits set in some random machine register.
223	 */
224	while ((c = getopt(argc, argv, "sf")) != -1)
225		switch (c) {
226		case 's':
227			requested_transition = single_user;
228			break;
229		case 'f':
230			runcom_mode = FASTBOOT;
231			break;
232		default:
233			warning("unrecognized flag '-%c'", c);
234			break;
235		}
236
237	if (optind != argc)
238		warning("ignoring excess arguments");
239
240	/*
241	 * We catch or block signals rather than ignore them,
242	 * so that they get reset on exec.
243	 */
244	handle(badsys, SIGSYS, 0);
245	handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV,
246	    SIGBUS, SIGXCPU, SIGXFSZ, 0);
247	handle(transition_handler, SIGHUP, SIGTERM, SIGTSTP, SIGUSR1,
248	    SIGUSR2, 0);
249	handle(alrm_handler, SIGALRM, 0);
250	sigfillset(&mask);
251	delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
252	    SIGXCPU, SIGXFSZ, SIGHUP, SIGTERM, SIGUSR1, SIGUSR2,
253	    SIGTSTP, SIGALRM, 0);
254	sigprocmask(SIG_SETMASK, &mask, NULL);
255	memset(&sa, 0, sizeof sa);
256	sigemptyset(&sa.sa_mask);
257	sa.sa_flags = 0;
258	sa.sa_handler = SIG_IGN;
259	(void) sigaction(SIGTTIN, &sa, NULL);
260	(void) sigaction(SIGTTOU, &sa, NULL);
261
262	/*
263	 * Paranoia.
264	 */
265	close(STDIN_FILENO);
266	close(STDOUT_FILENO);
267	close(STDERR_FILENO);
268
269	/*
270	 * Start the state machine.
271	 */
272	transition(requested_transition);
273
274	/*
275	 * Should never reach here.
276	 */
277	exit(1);
278}
279
280/*
281 * Associate a function with a signal handler.
282 */
283void
284handle(sig_t handler, ...)
285{
286	int sig;
287	struct sigaction sa;
288	sigset_t mask_everything;
289	va_list ap;
290
291	va_start(ap, handler);
292
293	memset(&sa, 0, sizeof sa);
294	sa.sa_handler = handler;
295	sigfillset(&mask_everything);
296
297	while ((sig = va_arg(ap, int))) {
298		sa.sa_mask = mask_everything;
299		/* XXX SA_RESTART? */
300		sa.sa_flags = sig == SIGCHLD ? SA_NOCLDSTOP : 0;
301		sigaction(sig, &sa, NULL);
302	}
303	va_end(ap);
304}
305
306/*
307 * Delete a set of signals from a mask.
308 */
309void
310delset(sigset_t *maskp, ...)
311{
312	int sig;
313	va_list ap;
314
315	va_start(ap, maskp);
316	while ((sig = va_arg(ap, int)))
317		sigdelset(maskp, sig);
318	va_end(ap);
319}
320
321/*
322 * Log a message and sleep for a while (to give someone an opportunity
323 * to read it and to save log or hardcopy output if the problem is chronic).
324 * NB: should send a message to the session logger to avoid blocking.
325 */
326void
327stall(char *message, ...)
328{
329	va_list ap;
330
331	va_start(ap, message);
332	vsyslog(LOG_ALERT, message, ap);
333	va_end(ap);
334	closelog();
335	sleep(STALL_TIMEOUT);
336}
337
338/*
339 * Like stall(), but doesn't sleep.
340 * If cpp had variadic macros, the two functions could be #defines for another.
341 * NB: should send a message to the session logger to avoid blocking.
342 */
343void
344warning(char *message, ...)
345{
346	va_list ap;
347
348	va_start(ap, message);
349	vsyslog(LOG_ALERT, message, ap);
350	va_end(ap);
351	closelog();
352}
353
354/*
355 * Log an emergency message.
356 * NB: should send a message to the session logger to avoid blocking.
357 */
358void
359emergency(char *message, ...)
360{
361	struct syslog_data sdata = SYSLOG_DATA_INIT;
362	va_list ap;
363
364	va_start(ap, message);
365	vsyslog_r(LOG_EMERG, &sdata, message, ap);
366	va_end(ap);
367}
368
369/*
370 * Catch a SIGSYS signal.
371 *
372 * These may arise if a system does not support sysctl.
373 * We tolerate up to 25 of these, then throw in the towel.
374 */
375void
376badsys(int sig)
377{
378	static int badcount = 0;
379
380	if (badcount++ < 25)
381		return;
382	disaster(sig);
383}
384
385/*
386 * Catch an unexpected signal.
387 */
388void
389disaster(int sig)
390{
391	emergency("fatal signal: %s", strsignal(sig));
392
393	sleep(STALL_TIMEOUT);
394	_exit(sig);		/* reboot */
395}
396
397/*
398 * Get the security level of the kernel.
399 */
400int
401getsecuritylevel(void)
402{
403#ifdef KERN_SECURELVL
404	int name[2], curlevel;
405	size_t len;
406
407	name[0] = CTL_KERN;
408	name[1] = KERN_SECURELVL;
409	len = sizeof curlevel;
410	if (sysctl(name, 2, &curlevel, &len, NULL, 0) == -1) {
411		emergency("cannot get kernel security level: %s",
412		    strerror(errno));
413		return (-1);
414	}
415	return (curlevel);
416#else
417	return (-1);
418#endif
419}
420
421/*
422 * Set the security level of the kernel.
423 */
424void
425setsecuritylevel(int newlevel)
426{
427#ifdef KERN_SECURELVL
428	int name[2], curlevel;
429
430	curlevel = getsecuritylevel();
431	if (newlevel == curlevel)
432		return;
433	name[0] = CTL_KERN;
434	name[1] = KERN_SECURELVL;
435	if (sysctl(name, 2, NULL, NULL, &newlevel, sizeof newlevel) == -1) {
436		emergency(
437		    "cannot change kernel security level from %d to %d: %s",
438		    curlevel, newlevel, strerror(errno));
439		return;
440	}
441#ifdef SECURE
442	warning("kernel security level changed from %d to %d",
443	    curlevel, newlevel);
444#endif
445#endif
446}
447
448/*
449 * Change states in the finite state machine.
450 * The initial state is passed as an argument.
451 */
452void
453transition(state_t s)
454{
455	for (;;)
456		s = (state_t) (*s)();
457}
458
459/*
460 * Close out the accounting files for a login session.
461 * NB: should send a message to the session logger to avoid blocking.
462 */
463void
464clear_session_logs(session_t *sp)
465{
466	char *line = sp->se_device + sizeof(_PATH_DEV) - 1;
467
468	if (logout(line))
469		logwtmp(line, "", "");
470}
471
472/*
473 * Start a session and allocate a controlling terminal.
474 * Only called by children of init after forking.
475 */
476void
477setctty(char *name)
478{
479	int fd;
480
481	(void) revoke(name);
482	sleep(2);			/* leave DTR low */
483	if ((fd = open(name, O_RDWR)) == -1) {
484		stall("can't open %s: %m", name);
485		_exit(1);
486	}
487	if (login_tty(fd) == -1) {
488		stall("can't get %s for controlling terminal: %m", name);
489		_exit(1);
490	}
491}
492
493/*
494 * Bring the system up single user.
495 */
496state_func_t
497single_user(void)
498{
499	pid_t pid, wpid;
500	int status;
501	sigset_t mask;
502	char shell[MAXPATHLEN];		/* Allocate space here */
503	char name[MAXPATHLEN];		/* Name (argv[0]) of shell */
504	char *argv[2];
505#ifdef SECURE
506	struct ttyent *typ;
507	struct passwd *pp;
508	static const char banner[] =
509		"Enter root password, or ^D to go multi-user\n";
510	char *clear, *password;
511#endif
512
513	/* Init shell and name */
514	strlcpy(shell, _PATH_BSHELL, sizeof shell);
515	strlcpy(name, "-sh", sizeof name);
516
517	/*
518	 * If the kernel is in secure mode, downgrade it to insecure mode.
519	 */
520	if (getsecuritylevel() > 0)
521		setsecuritylevel(0);
522
523	if ((pid = fork()) == 0) {
524		/*
525		 * Start the single user session.
526		 */
527		setctty(_PATH_CONSOLE);
528
529#ifdef SECURE
530		/*
531		 * Check the root password.
532		 * We don't care if the console is 'on' by default;
533		 * it's the only tty that can be 'off' and 'secure'.
534		 */
535		typ = getttynam("console");
536		pp = getpwnam("root");
537		if (typ && (typ->ty_status & TTY_SECURE) == 0 && pp &&
538		    *pp->pw_passwd) {
539			write(STDERR_FILENO, banner, sizeof banner - 1);
540			for (;;) {
541				clear = getpass("Password:");
542				if (clear == 0 || *clear == '\0')
543					_exit(0);
544				password = crypt(clear, pp->pw_passwd);
545				memset(clear, 0, _PASSWORD_LEN);
546				if (strcmp(password, pp->pw_passwd) == 0)
547					break;
548				warning("single-user login failed\n");
549			}
550		}
551		endttyent();
552		endpwent();
553#endif /* SECURE */
554
555#ifdef DEBUGSHELL
556		{
557			char altshell[128], *cp = altshell;
558			int num;
559
560#define	SHREQUEST \
561	"Enter pathname of shell or RETURN for sh: "
562
563			(void)write(STDERR_FILENO,
564			    SHREQUEST, sizeof(SHREQUEST) - 1);
565			while ((num = read(STDIN_FILENO, cp, 1)) != -1 &&
566			    num != 0 && *cp != '\n' && cp < &altshell[127])
567				cp++;
568			*cp = '\0';
569
570			/* Copy in alternate shell */
571			if (altshell[0] != '\0'){
572				char *p;
573
574				/* Binary to exec */
575				strlcpy(shell, altshell, sizeof shell);
576
577				/* argv[0] */
578				p = strrchr(altshell, '/');
579				if(p == NULL) p = altshell;
580				else p++;
581
582				name[0] = '-';
583				strlcpy(&name[1], p, sizeof name -1);
584			}
585		}
586#endif /* DEBUGSHELL */
587
588		/*
589		 * Unblock signals.
590		 * We catch all the interesting ones,
591		 * and those are reset to SIG_DFL on exec.
592		 */
593		sigemptyset(&mask);
594		sigprocmask(SIG_SETMASK, &mask, NULL);
595
596		/*
597		 * Fire off a shell.
598		 * If the default one doesn't work, try the Bourne shell.
599		 */
600		argv[0] = name;
601		argv[1] = NULL;
602		setenv("PATH", _PATH_STDPATH, 1);
603		execv(shell, argv);
604		emergency("can't exec %s for single user: %m", shell);
605
606		argv[0] = "-sh";
607		argv[1] = NULL;
608		execv(_PATH_BSHELL, argv);
609		emergency("can't exec %s for single user: %m", _PATH_BSHELL);
610		sleep(STALL_TIMEOUT);
611		_exit(1);
612	}
613
614	if (pid == -1) {
615		/*
616		 * We are seriously hosed.  Do our best.
617		 */
618		emergency("can't fork single-user shell, trying again");
619		while (waitpid(-1, NULL, WNOHANG) > 0)
620			continue;
621		return (state_func_t) single_user;
622	}
623
624	requested_transition = 0;
625	do {
626		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
627			collect_child(wpid);
628		if (wpid == -1) {
629			if (errno == EINTR)
630				continue;
631			warning("wait for single-user shell failed: %m; restarting");
632			return (state_func_t) single_user;
633		}
634		if (wpid == pid && WIFSTOPPED(status)) {
635			warning("init: shell stopped, restarting\n");
636			kill(pid, SIGCONT);
637			wpid = -1;
638		}
639	} while (wpid != pid && !requested_transition);
640
641	if (requested_transition)
642		return (state_func_t) requested_transition;
643
644	if (!WIFEXITED(status)) {
645		if (WTERMSIG(status) == SIGKILL) {
646			/*
647			 *  reboot(8) killed shell?
648			 */
649			warning("single user shell terminated.");
650			sleep(STALL_TIMEOUT);
651			_exit(0);
652		} else {
653			warning("single user shell terminated, restarting");
654			return (state_func_t) single_user;
655		}
656	}
657
658	runcom_mode = FASTBOOT;
659	return (state_func_t) runcom;
660}
661
662/*
663 * Run the system startup script.
664 */
665state_func_t
666runcom(void)
667{
668	pid_t pid, wpid;
669	int status;
670	char *argv[4];
671	struct sigaction sa;
672
673	if ((pid = fork()) == 0) {
674		memset(&sa, 0, sizeof sa);
675		sigemptyset(&sa.sa_mask);
676		sa.sa_flags = 0;
677		sa.sa_handler = SIG_IGN;
678		(void) sigaction(SIGTSTP, &sa, NULL);
679		(void) sigaction(SIGHUP, &sa, NULL);
680
681		setctty(_PATH_CONSOLE);
682
683		argv[0] = "sh";
684		argv[1] = _PATH_RUNCOM;
685		argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : 0;
686		argv[3] = 0;
687
688		sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
689
690		setprocresources(RESOURCE_RC);
691
692		execv(_PATH_BSHELL, argv);
693		stall("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNCOM);
694		_exit(1);	/* force single user mode */
695	}
696
697	if (pid == -1) {
698		emergency("can't fork for %s on %s: %m",
699			_PATH_BSHELL, _PATH_RUNCOM);
700		while (waitpid(-1, NULL, WNOHANG) > 0)
701			continue;
702		sleep(STALL_TIMEOUT);
703		return (state_func_t) single_user;
704	}
705
706	/*
707	 * Copied from single_user().  This is a bit paranoid.
708	 */
709	do {
710		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
711			collect_child(wpid);
712		if (wpid == -1) {
713			if (errno == EINTR)
714				continue;
715			warning("wait for %s on %s failed: %m; going to single user mode",
716			    _PATH_BSHELL, _PATH_RUNCOM);
717			return (state_func_t) single_user;
718		}
719		if (wpid == pid && WIFSTOPPED(status)) {
720			warning("init: %s on %s stopped, restarting\n",
721			    _PATH_BSHELL, _PATH_RUNCOM);
722			kill(pid, SIGCONT);
723			wpid = -1;
724		}
725	} while (wpid != pid);
726
727	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
728	    requested_transition == catatonia) {
729		/* /etc/rc executed /sbin/reboot; wait for the end quietly */
730		sigset_t s;
731
732		sigfillset(&s);
733		for (;;)
734			sigsuspend(&s);
735	}
736
737	if (!WIFEXITED(status)) {
738		warning("%s on %s terminated abnormally, going to single user mode",
739		    _PATH_BSHELL, _PATH_RUNCOM);
740		return (state_func_t) single_user;
741	}
742
743	if (WEXITSTATUS(status))
744		return (state_func_t) single_user;
745
746	runcom_mode = AUTOBOOT;		/* the default */
747	/* NB: should send a message to the session logger to avoid blocking. */
748	logwtmp("~", "reboot", "");
749	return (state_func_t) read_ttys;
750}
751
752/*
753 * Open the session database.
754 *
755 * NB: We could pass in the size here; is it necessary?
756 */
757int
758start_session_db(void)
759{
760	if (session_db && (*session_db->close)(session_db))
761		emergency("session database close: %s", strerror(errno));
762	if ((session_db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == 0) {
763		emergency("session database open: %s", strerror(errno));
764		return (1);
765	}
766	return (0);
767}
768
769/*
770 * Add a new login session.
771 */
772void
773add_session(session_t *sp)
774{
775	DBT key;
776	DBT data;
777
778	key.data = &sp->se_process;
779	key.size = sizeof sp->se_process;
780	data.data = &sp;
781	data.size = sizeof sp;
782
783	if ((*session_db->put)(session_db, &key, &data, 0))
784		emergency("insert %d: %s", sp->se_process, strerror(errno));
785}
786
787/*
788 * Delete an old login session.
789 */
790void
791del_session(session_t *sp)
792{
793	DBT key;
794
795	key.data = &sp->se_process;
796	key.size = sizeof sp->se_process;
797
798	if ((*session_db->del)(session_db, &key, 0))
799		emergency("delete %d: %s", sp->se_process, strerror(errno));
800}
801
802/*
803 * Look up a login session by pid.
804 */
805session_t *
806find_session(pid_t pid)
807{
808	DBT key;
809	DBT data;
810	session_t *ret;
811
812	key.data = &pid;
813	key.size = sizeof pid;
814	if ((*session_db->get)(session_db, &key, &data, 0) != 0)
815		return (0);
816	memcpy(&ret, data.data, sizeof(ret));
817	return (ret);
818}
819
820/*
821 * Construct an argument vector from a command line.
822 */
823char **
824construct_argv(char *command)
825{
826	int argc = 0;
827	char **argv = (char **) malloc(((strlen(command) + 1) / 2 + 1) *
828	    sizeof (char *));
829	static const char separators[] = " \t";
830
831	if (argv == NULL)
832		return (0);
833
834	if ((argv[argc++] = strtok(command, separators)) == 0) {
835		free(argv);
836		return (0);
837	}
838	while ((argv[argc++] = strtok(NULL, separators)))
839		continue;
840	return (argv);
841}
842
843/*
844 * Deallocate a session descriptor.
845 */
846void
847free_session(session_t *sp)
848{
849	free(sp->se_device);
850	if (sp->se_getty) {
851		free(sp->se_getty);
852		free(sp->se_getty_argv);
853	}
854	if (sp->se_window) {
855		free(sp->se_window);
856		free(sp->se_window_argv);
857	}
858	free(sp);
859}
860
861/*
862 * Allocate a new session descriptor.
863 */
864session_t *
865new_session(session_t *sprev, int session_index, struct ttyent *typ)
866{
867	session_t *sp;
868
869	if ((typ->ty_status & TTY_ON) == 0 ||
870	    typ->ty_name == 0 ||
871	    typ->ty_getty == 0)
872		return (0);
873
874	sp = (session_t *) malloc(sizeof (session_t));
875	memset(sp, 0, sizeof *sp);
876
877	sp->se_flags = SE_PRESENT;
878	sp->se_index = session_index;
879
880	if (asprintf(&sp->se_device, "%s%s", _PATH_DEV, typ->ty_name) == -1)
881		err(1, "asprintf");
882
883	if (setupargv(sp, typ) == 0) {
884		free_session(sp);
885		return (0);
886	}
887
888	sp->se_next = 0;
889	if (sprev == 0) {
890		sessions = sp;
891		sp->se_prev = 0;
892	} else {
893		sprev->se_next = sp;
894		sp->se_prev = sprev;
895	}
896
897	return (sp);
898}
899
900/*
901 * Calculate getty and if useful window argv vectors.
902 */
903int
904setupargv(session_t *sp, struct ttyent *typ)
905{
906	if (sp->se_getty) {
907		free(sp->se_getty);
908		free(sp->se_getty_argv);
909	}
910	if (asprintf(&sp->se_getty, "%s %s", typ->ty_getty, typ->ty_name) == -1)
911		err(1, "asprintf");
912	sp->se_getty_argv = construct_argv(sp->se_getty);
913	if (sp->se_getty_argv == 0) {
914		warning("can't parse getty for port %s", sp->se_device);
915		free(sp->se_getty);
916		sp->se_getty = 0;
917		return (0);
918	}
919	if (typ->ty_window) {
920		if (sp->se_window)
921			free(sp->se_window);
922		sp->se_window = strdup(typ->ty_window);
923		if (sp->se_window == NULL) {
924			warning("can't allocate window");
925			return (0);
926		}
927		sp->se_window_argv = construct_argv(sp->se_window);
928		if (sp->se_window_argv == NULL) {
929			warning("can't parse window for port %s",
930			    sp->se_device);
931			free(sp->se_window);
932			sp->se_window = NULL;
933			return (0);
934		}
935	}
936	return (1);
937}
938
939/*
940 * Walk the list of ttys and create sessions for each active line.
941 */
942state_func_t
943read_ttys(void)
944{
945	int session_index = 0;
946	session_t *sp, *snext;
947	struct ttyent *typ;
948
949	/*
950	 * Destroy any previous session state.
951	 * There shouldn't be any, but just in case...
952	 */
953	for (sp = sessions; sp; sp = snext) {
954		if (sp->se_process)
955			clear_session_logs(sp);
956		snext = sp->se_next;
957		free_session(sp);
958	}
959	sessions = 0;
960	if (start_session_db())
961		return (state_func_t) single_user;
962
963	/*
964	 * Allocate a session entry for each active port.
965	 * Note that sp starts at 0.
966	 */
967	while ((typ = getttyent()))
968		if ((snext = new_session(sp, ++session_index, typ)))
969			sp = snext;
970
971	endttyent();
972
973	return (state_func_t) multi_user;
974}
975
976/*
977 * Start a window system running.
978 */
979void
980start_window_system(session_t *sp)
981{
982	pid_t pid;
983	sigset_t mask;
984
985	if ((pid = fork()) == -1) {
986		emergency("can't fork for window system on port %s: %m",
987		    sp->se_device);
988		/* hope that getty fails and we can try again */
989		return;
990	}
991
992	if (pid)
993		return;
994
995	sigemptyset(&mask);
996	sigprocmask(SIG_SETMASK, &mask, NULL);
997
998	if (setsid() < 0)
999		emergency("setsid failed (window) %m");
1000
1001	setprocresources(RESOURCE_WINDOW);
1002
1003	execv(sp->se_window_argv[0], sp->se_window_argv);
1004	stall("can't exec window system '%s' for port %s: %m",
1005	    sp->se_window_argv[0], sp->se_device);
1006	_exit(1);
1007}
1008
1009/*
1010 * Start a login session running.
1011 * For first open, man-handle tty directly to determine if it
1012 * really exists. It is not efficient to spawn gettys on devices
1013 * that do not exist.
1014 */
1015pid_t
1016start_getty(session_t *sp)
1017{
1018	pid_t pid;
1019	sigset_t mask;
1020	time_t current_time = time(NULL);
1021	int p[2], new = 1;
1022
1023	if (sp->se_flags & SE_DEVEXISTS)
1024		new = 0;
1025
1026	if (new) {
1027		if (pipe(p) == -1)
1028			return (-1);
1029	}
1030
1031	/*
1032	 * fork(), not vfork() -- we can't afford to block.
1033	 */
1034	if ((pid = fork()) == -1) {
1035		emergency("can't fork for getty on port %s: %m", sp->se_device);
1036		return (-1);
1037	}
1038
1039	if (pid) {
1040		if (new) {
1041			char c;
1042
1043			close(p[1]);
1044			if (read(p[0], &c, 1) != 1) {
1045				close(p[0]);
1046				return (-1);
1047			}
1048			close(p[0]);
1049			if (c == '1')
1050				sp->se_flags |= SE_DEVEXISTS;
1051			else
1052				sp->se_flags |= SE_SHUTDOWN;
1053		}
1054		return (pid);
1055	}
1056	if (new) {
1057		int fd;
1058
1059		close(p[0]);
1060		fd = open(sp->se_device, O_RDONLY | O_NONBLOCK, 0666);
1061		if (fd == -1 && (errno == ENXIO || errno == ENOENT ||
1062		    errno == EISDIR)) {
1063			(void)write(p[1], "0", 1);
1064			close(p[1]);
1065			_exit(1);
1066		}
1067		(void)write(p[1], "1", 1);
1068		close(p[1]);
1069		close(fd);
1070		sleep(1);
1071	}
1072
1073	if (current_time > sp->se_started &&
1074	    current_time - sp->se_started < GETTY_SPACING) {
1075		warning("getty repeating too quickly on port %s, sleeping",
1076		    sp->se_device);
1077		sleep((unsigned) GETTY_SLEEP);
1078	}
1079
1080	if (sp->se_window) {
1081		start_window_system(sp);
1082		sleep(WINDOW_WAIT);
1083	}
1084
1085	sigemptyset(&mask);
1086	sigprocmask(SIG_SETMASK, &mask, NULL);
1087
1088	setprocresources(RESOURCE_GETTY);
1089
1090	execv(sp->se_getty_argv[0], sp->se_getty_argv);
1091	stall("can't exec getty '%s' for port %s: %m",
1092	    sp->se_getty_argv[0], sp->se_device);
1093	_exit(1);
1094}
1095
1096/*
1097 * Collect exit status for a child.
1098 * If an exiting login, start a new login running.
1099 */
1100void
1101collect_child(pid_t pid)
1102{
1103	session_t *sp, *sprev, *snext;
1104
1105	if (sessions == NULL)
1106		return;
1107
1108	if ((sp = find_session(pid)) == NULL)
1109		return;
1110
1111	clear_session_logs(sp);
1112	login_fbtab(sp->se_device + sizeof(_PATH_DEV) - 1, 0, 0);
1113	del_session(sp);
1114	sp->se_process = 0;
1115
1116	if (sp->se_flags & SE_SHUTDOWN) {
1117		if ((sprev = sp->se_prev))
1118			sprev->se_next = sp->se_next;
1119		else
1120			sessions = sp->se_next;
1121		if ((snext = sp->se_next))
1122			snext->se_prev = sp->se_prev;
1123		free_session(sp);
1124		return;
1125	}
1126
1127	if ((pid = start_getty(sp)) == -1) {
1128		/* serious trouble */
1129		requested_transition = clean_ttys;
1130		return;
1131	}
1132
1133	sp->se_process = pid;
1134	sp->se_started = time(NULL);
1135	add_session(sp);
1136}
1137
1138/*
1139 * Catch a signal and request a state transition.
1140 */
1141void
1142transition_handler(int sig)
1143{
1144
1145	switch (sig) {
1146	case SIGHUP:
1147		requested_transition = clean_ttys;
1148		break;
1149	case SIGTERM:
1150		requested_transition = death;
1151		break;
1152	case SIGUSR1:
1153		requested_transition = nice_death;
1154		break;
1155	case SIGUSR2:
1156		requested_transition = hard_death;
1157		break;
1158	case SIGTSTP:
1159		requested_transition = catatonia;
1160		break;
1161	default:
1162		requested_transition = 0;
1163		break;
1164	}
1165}
1166
1167/*
1168 * Take the system multiuser.
1169 */
1170state_func_t
1171multi_user(void)
1172{
1173	pid_t pid;
1174	session_t *sp;
1175
1176	requested_transition = 0;
1177
1178	/*
1179	 * If the administrator has not set the security level to -1
1180	 * to indicate that the kernel should not run multiuser in secure
1181	 * mode, and the run script has not set a higher level of security
1182	 * than level 1, then put the kernel into secure mode.
1183	 */
1184	if (getsecuritylevel() == 0)
1185		setsecuritylevel(1);
1186
1187	for (sp = sessions; sp; sp = sp->se_next) {
1188		if (sp->se_process)
1189			continue;
1190		if ((pid = start_getty(sp)) == -1) {
1191			/* serious trouble */
1192			requested_transition = clean_ttys;
1193			break;
1194		}
1195		sp->se_process = pid;
1196		sp->se_started = time(NULL);
1197		add_session(sp);
1198	}
1199
1200	while (!requested_transition)
1201		if ((pid = waitpid(-1, NULL, 0)) != -1)
1202			collect_child(pid);
1203
1204	return (state_func_t) requested_transition;
1205}
1206
1207/*
1208 * This is an n-squared algorithm.  We hope it isn't run often...
1209 */
1210state_func_t
1211clean_ttys(void)
1212{
1213	session_t *sp, *sprev;
1214	struct ttyent *typ;
1215	int session_index = 0;
1216	int devlen;
1217
1218	for (sp = sessions; sp; sp = sp->se_next)
1219		sp->se_flags &= ~SE_PRESENT;
1220
1221	devlen = sizeof(_PATH_DEV) - 1;
1222	while ((typ = getttyent())) {
1223		++session_index;
1224
1225		for (sprev = 0, sp = sessions; sp; sprev = sp, sp = sp->se_next)
1226			if (strcmp(typ->ty_name, sp->se_device + devlen) == 0)
1227				break;
1228
1229		if (sp) {
1230			sp->se_flags |= SE_PRESENT;
1231			if (sp->se_index != session_index) {
1232				warning("port %s changed utmp index from %d to %d",
1233				    sp->se_device, sp->se_index,
1234				    session_index);
1235				sp->se_index = session_index;
1236			}
1237			if ((typ->ty_status & TTY_ON) == 0 ||
1238			    typ->ty_getty == 0) {
1239				sp->se_flags |= SE_SHUTDOWN;
1240				kill(sp->se_process, SIGHUP);
1241				continue;
1242			}
1243			sp->se_flags &= ~SE_SHUTDOWN;
1244			if (setupargv(sp, typ) == 0) {
1245				warning("can't parse getty for port %s",
1246				    sp->se_device);
1247				sp->se_flags |= SE_SHUTDOWN;
1248				kill(sp->se_process, SIGHUP);
1249			}
1250			continue;
1251		}
1252
1253		new_session(sprev, session_index, typ);
1254	}
1255
1256	endttyent();
1257
1258	for (sp = sessions; sp; sp = sp->se_next)
1259		if ((sp->se_flags & SE_PRESENT) == 0) {
1260			sp->se_flags |= SE_SHUTDOWN;
1261			kill(sp->se_process, SIGHUP);
1262		}
1263
1264	return (state_func_t) multi_user;
1265}
1266
1267/*
1268 * Block further logins.
1269 */
1270state_func_t
1271catatonia(void)
1272{
1273	session_t *sp;
1274
1275	for (sp = sessions; sp; sp = sp->se_next)
1276		sp->se_flags |= SE_SHUTDOWN;
1277
1278	return (state_func_t) multi_user;
1279}
1280
1281/*
1282 * Note SIGALRM.
1283 */
1284void
1285alrm_handler(int sig)
1286{
1287	clang = 1;
1288}
1289
1290int death_howto = RB_HALT;
1291
1292/*
1293 * Bring the system down nicely, then we must powerdown because something
1294 * is very wrong.
1295 */
1296state_func_t
1297hard_death(void)
1298{
1299	death_howto |= RB_POWERDOWN;
1300	return nice_death();
1301}
1302
1303/*
1304 * Bring the system down to single user nicely, after run the shutdown script.
1305 */
1306state_func_t
1307nice_death(void)
1308{
1309	session_t *sp;
1310	int i;
1311	pid_t pid;
1312	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1313	int status;
1314
1315	for (sp = sessions; sp; sp = sp->se_next) {
1316		sp->se_flags &= ~SE_PRESENT;
1317		sp->se_flags |= SE_SHUTDOWN;
1318		kill(sp->se_process, SIGHUP);
1319	}
1320
1321	/* terminate the accounting process */
1322	acct(NULL);
1323
1324	/* NB: should send a message to the session logger to avoid blocking. */
1325	logwtmp("~", "shutdown", "");
1326
1327	if (access(_PATH_RUNCOM, R_OK) != -1) {
1328		pid_t pid;
1329		struct sigaction sa;
1330
1331		switch ((pid = fork())) {
1332		case -1:
1333			break;
1334		case 0:
1335
1336			memset(&sa, 0, sizeof sa);
1337			sigemptyset(&sa.sa_mask);
1338			sa.sa_flags = 0;
1339			sa.sa_handler = SIG_IGN;
1340			(void) sigaction(SIGTSTP, &sa, NULL);
1341			(void) sigaction(SIGHUP, &sa, NULL);
1342
1343			setctty(_PATH_CONSOLE);
1344
1345			sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
1346
1347			execl(_PATH_BSHELL, "sh", _PATH_RUNCOM, "shutdown",
1348			    (char *)NULL);
1349			stall("can't exec %s for %s %s: %m", _PATH_BSHELL,
1350			    _PATH_RUNCOM, "shutdown");
1351			_exit(1);
1352		default:
1353			waitpid(pid, &status, 0);
1354			if (WIFEXITED(status) && WEXITSTATUS(status) == 2)
1355				death_howto |= RB_POWERDOWN;
1356		}
1357	}
1358
1359	for (i = 0; i < 3; ++i) {
1360		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1361			goto die;
1362
1363		clang = 0;
1364		alarm(DEATH_WATCH);
1365		do {
1366			if ((pid = waitpid(-1, NULL, 0)) != -1)
1367				collect_child(pid);
1368		} while (clang == 0 && errno != ECHILD);
1369
1370		if (errno == ECHILD)
1371			goto die;
1372	}
1373
1374	warning("some processes would not die; ps axl advised");
1375
1376die:
1377	reboot(death_howto);
1378
1379	/* ... and if that fails.. oh well */
1380	return (state_func_t) single_user;
1381}
1382
1383/*
1384 * Bring the system down to single user.
1385 */
1386state_func_t
1387death(void)
1388{
1389	session_t *sp;
1390	int i;
1391	pid_t pid;
1392	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1393
1394	/* terminate the accounting process */
1395	acct(NULL);
1396
1397	for (sp = sessions; sp; sp = sp->se_next)
1398		sp->se_flags |= SE_SHUTDOWN;
1399
1400	/* NB: should send a message to the session logger to avoid blocking. */
1401	logwtmp("~", "shutdown", "");
1402
1403	for (i = 0; i < 3; ++i) {
1404		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1405			return (state_func_t) single_user;
1406
1407		clang = 0;
1408		alarm(DEATH_WATCH);
1409		do {
1410			if ((pid = waitpid(-1, NULL, 0)) != -1)
1411				collect_child(pid);
1412		} while (clang == 0 && errno != ECHILD);
1413
1414		if (errno == ECHILD)
1415			return (state_func_t) single_user;
1416	}
1417
1418	warning("some processes would not die; ps axl advised");
1419
1420	return (state_func_t) single_user;
1421}
1422
1423#ifdef LOGIN_CAP
1424void
1425setprocresources(char *class)
1426{
1427	login_cap_t *lc;
1428
1429	if ((lc = login_getclass(class)) != NULL) {
1430		setusercontext(lc, NULL, 0,
1431		    LOGIN_SETPRIORITY|LOGIN_SETRESOURCES|LOGIN_SETUMASK);
1432		login_close(lc);
1433	}
1434}
1435#endif
1436