init.c revision 1.63 
1/*	$OpenBSD: init.c,v 1.63 2017/03/02 10:38:09 natano 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#include <sys/types.h>
37#include <sys/reboot.h>
38#include <sys/sysctl.h>
39#include <sys/time.h>
40#include <sys/tree.h>
41#include <sys/wait.h>
42#include <machine/cpu.h>
43
44#include <err.h>
45#include <errno.h>
46#include <fcntl.h>
47#include <limits.h>
48#include <signal.h>
49#include <stdarg.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <syslog.h>
54#include <time.h>
55#include <ttyent.h>
56#include <unistd.h>
57#include <util.h>
58
59#ifdef SECURE
60#include <pwd.h>
61#include <readpassphrase.h>
62#endif
63
64#ifdef LOGIN_CAP
65#include <login_cap.h>
66#endif
67
68#include "pathnames.h"
69
70/*
71 * Sleep times; used to prevent thrashing.
72 */
73#define	GETTY_SPACING		 5	/* N secs minimum getty spacing */
74#define	GETTY_SLEEP		30	/* sleep N secs after spacing problem */
75#define	WINDOW_WAIT		 3	/* wait N secs after starting window */
76#define	STALL_TIMEOUT		30	/* wait N secs after warning */
77#define	DEATH_WATCH		10	/* wait N secs for procs to die */
78
79/*
80 * User-based resource limits.
81 */
82#define RESOURCE_RC		"daemon"
83#define RESOURCE_WINDOW		"default"
84#define RESOURCE_GETTY		"default"
85
86#ifndef DEFAULT_STATE
87#define DEFAULT_STATE		runcom
88#endif
89
90void handle(sig_t, ...);
91void delset(sigset_t *, ...);
92
93void stall(char *, ...);
94void warning(char *, ...);
95void emergency(char *, ...);
96void disaster(int);
97void badsys(int);
98
99typedef enum {
100	invalid_state,
101	single_user,
102	runcom,
103	read_ttys,
104	multi_user,
105	clean_ttys,
106	catatonia,
107	death,
108	do_reboot,
109	hard_death,
110	nice_death
111} state_t;
112typedef state_t (*state_func_t)(void);
113
114state_t f_single_user(void);
115state_t f_runcom(void);
116state_t f_read_ttys(void);
117state_t f_multi_user(void);
118state_t f_clean_ttys(void);
119state_t f_catatonia(void);
120state_t f_death(void);
121state_t f_do_reboot(void);
122state_t f_hard_death(void);
123state_t f_nice_death(void);
124
125state_func_t state_funcs[] = {
126	NULL,
127	f_single_user,
128	f_runcom,
129	f_read_ttys,
130	f_multi_user,
131	f_clean_ttys,
132	f_catatonia,
133	f_death,
134	f_do_reboot,
135	f_hard_death,
136	f_nice_death
137};
138
139enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;
140
141void transition(state_t);
142volatile sig_atomic_t requested_transition = DEFAULT_STATE;
143
144void setctty(char *);
145
146typedef struct init_session {
147	int	se_index;		/* index of entry in ttys file */
148	pid_t	se_process;		/* controlling process */
149	time_t	se_started;		/* used to avoid thrashing */
150	int	se_flags;		/* status of session */
151#define	SE_SHUTDOWN	0x1		/* session won't be restarted */
152#define	SE_PRESENT	0x2		/* session is in /etc/ttys */
153#define	SE_DEVEXISTS	0x4		/* open does not result in ENODEV */
154	char	*se_device;		/* filename of port */
155	char	*se_getty;		/* what to run on that port */
156	char	**se_getty_argv;	/* pre-parsed argument array */
157	char	*se_window;		/* window system (started only once) */
158	char	**se_window_argv;	/* pre-parsed argument array */
159	struct	init_session *se_prev;
160	struct	init_session *se_next;
161	RB_ENTRY(init_session) se_entry;
162} session_t;
163
164static int cmp_sessions(session_t *, session_t *);
165RB_HEAD(session_tree, init_session) session_tree = RB_INITIALIZER(session_tree);
166RB_PROTOTYPE(session_tree, init_session, se_entry, cmp_sessions);
167RB_GENERATE(session_tree, init_session, se_entry, cmp_sessions);
168
169void free_session(session_t *);
170session_t *new_session(session_t *, int, struct ttyent *);
171session_t *sessions;
172
173char **construct_argv(char *);
174void start_window_system(session_t *);
175void collect_child(pid_t);
176pid_t start_getty(session_t *);
177void transition_handler(int);
178void alrm_handler(int);
179void setsecuritylevel(int);
180int getsecuritylevel(void);
181int setupargv(session_t *, struct ttyent *);
182int clang;
183
184#ifdef LOGIN_CAP
185void setprocresources(char *);
186#else
187#define setprocresources(p)
188#endif
189
190void clear_session_logs(session_t *);
191
192void add_session(session_t *);
193void del_session(session_t *);
194session_t *find_session(pid_t);
195
196/*
197 * The mother of all processes.
198 */
199int
200main(int argc, char *argv[])
201{
202	int c, fd;
203	struct sigaction sa;
204	sigset_t mask;
205
206	/* Dispose of random users. */
207	if (getuid() != 0) {
208		(void)fprintf(stderr, "init: %s\n", strerror(EPERM));
209		exit (1);
210	}
211
212	/* System V users like to reexec init. */
213	if (getpid() != 1) {
214		(void)fprintf(stderr, "init: already running\n");
215		exit (1);
216	}
217
218	/*
219	 * Paranoia.
220	 */
221	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
222		(void)dup2(fd, STDIN_FILENO);
223		(void)dup2(fd, STDOUT_FILENO);
224		(void)dup2(fd, STDERR_FILENO);
225		if (fd > 2)
226			(void)close(fd);
227	}
228
229	/*
230	 * Note that this does NOT open a file...
231	 * Does 'init' deserve its own facility number?
232	 */
233	openlog("init", LOG_CONS|LOG_ODELAY, LOG_AUTH);
234
235	/*
236	 * Create an initial session.
237	 */
238	if (setsid() < 0)
239		warning("initial setsid() failed: %m");
240
241	/*
242	 * Establish an initial user so that programs running
243	 * single user do not freak out and die (like passwd).
244	 */
245	if (setlogin("root") < 0)
246		warning("setlogin() failed: %m");
247
248	/*
249	 * This code assumes that we always get arguments through flags,
250	 * never through bits set in some random machine register.
251	 */
252	while ((c = getopt(argc, argv, "sf")) != -1)
253		switch (c) {
254		case 's':
255			requested_transition = single_user;
256			break;
257		case 'f':
258			runcom_mode = FASTBOOT;
259			break;
260		default:
261			warning("unrecognized flag '-%c'", c);
262			break;
263		}
264
265	if (optind != argc)
266		warning("ignoring excess arguments");
267
268	/*
269	 * We catch or block signals rather than ignore them,
270	 * so that they get reset on exec.
271	 */
272	handle(badsys, SIGSYS, 0);
273	handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV,
274	    SIGBUS, SIGXCPU, SIGXFSZ, 0);
275	handle(transition_handler, SIGHUP, SIGINT, SIGTERM, SIGTSTP,
276            SIGUSR1, SIGUSR2, 0);
277	handle(alrm_handler, SIGALRM, 0);
278	sigfillset(&mask);
279	delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
280	    SIGXCPU, SIGXFSZ, SIGHUP, SIGINT, SIGTERM, SIGUSR1, SIGUSR2,
281	    SIGTSTP, SIGALRM, 0);
282	sigprocmask(SIG_SETMASK, &mask, NULL);
283	memset(&sa, 0, sizeof sa);
284	sigemptyset(&sa.sa_mask);
285	sa.sa_flags = 0;
286	sa.sa_handler = SIG_IGN;
287	(void) sigaction(SIGTTIN, &sa, NULL);
288	(void) sigaction(SIGTTOU, &sa, NULL);
289
290	/*
291	 * Start the state machine.
292	 */
293	transition(requested_transition);
294
295	/*
296	 * Should never reach here.
297	 */
298	exit(1);
299}
300
301/*
302 * Associate a function with a signal handler.
303 */
304void
305handle(sig_t handler, ...)
306{
307	int sig;
308	struct sigaction sa;
309	sigset_t mask_everything;
310	va_list ap;
311
312	va_start(ap, handler);
313
314	memset(&sa, 0, sizeof sa);
315	sa.sa_handler = handler;
316	sigfillset(&mask_everything);
317
318	while ((sig = va_arg(ap, int))) {
319		sa.sa_mask = mask_everything;
320		/* XXX SA_RESTART? */
321		sa.sa_flags = sig == SIGCHLD ? SA_NOCLDSTOP : 0;
322		sigaction(sig, &sa, NULL);
323	}
324	va_end(ap);
325}
326
327/*
328 * Delete a set of signals from a mask.
329 */
330void
331delset(sigset_t *maskp, ...)
332{
333	int sig;
334	va_list ap;
335
336	va_start(ap, maskp);
337	while ((sig = va_arg(ap, int)))
338		sigdelset(maskp, sig);
339	va_end(ap);
340}
341
342/*
343 * Log a message and sleep for a while (to give someone an opportunity
344 * to read it and to save log or hardcopy output if the problem is chronic).
345 * NB: should send a message to the session logger to avoid blocking.
346 */
347void
348stall(char *message, ...)
349{
350	va_list ap;
351
352	va_start(ap, message);
353	vsyslog(LOG_ALERT, message, ap);
354	va_end(ap);
355	closelog();
356	sleep(STALL_TIMEOUT);
357}
358
359/*
360 * Like stall(), but doesn't sleep.
361 * If cpp had variadic macros, the two functions could be #defines for another.
362 * NB: should send a message to the session logger to avoid blocking.
363 */
364void
365warning(char *message, ...)
366{
367	va_list ap;
368
369	va_start(ap, message);
370	vsyslog(LOG_ALERT, message, ap);
371	va_end(ap);
372	closelog();
373}
374
375/*
376 * Log an emergency message.
377 * NB: should send a message to the session logger to avoid blocking.
378 */
379void
380emergency(char *message, ...)
381{
382	struct syslog_data sdata = SYSLOG_DATA_INIT;
383	va_list ap;
384
385	va_start(ap, message);
386	vsyslog_r(LOG_EMERG, &sdata, message, ap);
387	va_end(ap);
388}
389
390/*
391 * Catch a SIGSYS signal.
392 *
393 * These may arise if a system does not support sysctl.
394 * We tolerate up to 25 of these, then throw in the towel.
395 */
396void
397badsys(int sig)
398{
399	static int badcount = 0;
400
401	if (badcount++ < 25)
402		return;
403	disaster(sig);
404}
405
406/*
407 * Catch an unexpected signal.
408 */
409void
410disaster(int sig)
411{
412	emergency("fatal signal: %s", strsignal(sig));
413
414	sleep(STALL_TIMEOUT);
415	_exit(sig);		/* reboot */
416}
417
418/*
419 * Get the security level of the kernel.
420 */
421int
422getsecuritylevel(void)
423{
424#ifdef KERN_SECURELVL
425	int name[2], curlevel;
426	size_t len;
427
428	name[0] = CTL_KERN;
429	name[1] = KERN_SECURELVL;
430	len = sizeof curlevel;
431	if (sysctl(name, 2, &curlevel, &len, NULL, 0) == -1) {
432		emergency("cannot get kernel security level: %s",
433		    strerror(errno));
434		return (-1);
435	}
436	return (curlevel);
437#else
438	return (-1);
439#endif
440}
441
442/*
443 * Set the security level of the kernel.
444 */
445void
446setsecuritylevel(int newlevel)
447{
448#ifdef KERN_SECURELVL
449	int name[2], curlevel;
450
451	curlevel = getsecuritylevel();
452	if (newlevel == curlevel)
453		return;
454	name[0] = CTL_KERN;
455	name[1] = KERN_SECURELVL;
456	if (sysctl(name, 2, NULL, NULL, &newlevel, sizeof newlevel) == -1) {
457		emergency(
458		    "cannot change kernel security level from %d to %d: %s",
459		    curlevel, newlevel, strerror(errno));
460		return;
461	}
462#ifdef SECURE
463	warning("kernel security level changed from %d to %d",
464	    curlevel, newlevel);
465#endif
466#endif
467}
468
469/*
470 * Change states in the finite state machine.
471 * The initial state is passed as an argument.
472 */
473void
474transition(state_t s)
475{
476	for (;;)
477		s = (*state_funcs[s])();
478}
479
480/*
481 * Close out the accounting files for a login session.
482 * NB: should send a message to the session logger to avoid blocking.
483 */
484void
485clear_session_logs(session_t *sp)
486{
487	char *line = sp->se_device + sizeof(_PATH_DEV) - 1;
488
489	if (logout(line))
490		logwtmp(line, "", "");
491}
492
493/*
494 * Start a session and allocate a controlling terminal.
495 * Only called by children of init after forking.
496 */
497void
498setctty(char *name)
499{
500	int fd;
501
502	(void) revoke(name);
503	sleep(2);			/* leave DTR low */
504	if ((fd = open(name, O_RDWR)) == -1) {
505		stall("can't open %s: %m", name);
506		_exit(1);
507	}
508	if (login_tty(fd) == -1) {
509		stall("can't get %s for controlling terminal: %m", name);
510		_exit(1);
511	}
512}
513
514/*
515 * Bring the system up single user.
516 */
517state_t
518f_single_user(void)
519{
520	pid_t pid, wpid;
521	int status;
522	sigset_t mask;
523	char shell[PATH_MAX];		/* Allocate space here */
524	char name[PATH_MAX];		/* Name (argv[0]) of shell */
525	char *argv[2];
526#ifdef SECURE
527	struct ttyent *typ;
528	struct passwd *pp;
529	static const char banner[] =
530		"Enter root password, or ^D to go multi-user\n";
531	char *clear;
532	char pbuf[1024];
533#endif
534
535	/* Init shell and name */
536	strlcpy(shell, _PATH_BSHELL, sizeof shell);
537	strlcpy(name, "-sh", sizeof name);
538
539	/*
540	 * If the kernel is in secure mode, downgrade it to insecure mode.
541	 */
542	if (getsecuritylevel() > 0)
543		setsecuritylevel(0);
544
545	if ((pid = fork()) == 0) {
546		/*
547		 * Start the single user session.
548		 */
549		setctty(_PATH_CONSOLE);
550
551#ifdef SECURE
552		/*
553		 * Check the root password.
554		 * We don't care if the console is 'on' by default;
555		 * it's the only tty that can be 'off' and 'secure'.
556		 */
557		typ = getttynam("console");
558		pp = getpwnam_shadow("root");
559		if (typ && (typ->ty_status & TTY_SECURE) == 0 && pp &&
560		    *pp->pw_passwd) {
561			write(STDERR_FILENO, banner, sizeof banner - 1);
562			for (;;) {
563				int ok = 0;
564				clear = readpassphrase("Password:", pbuf, sizeof(pbuf), RPP_ECHO_OFF);
565				if (clear == NULL || *clear == '\0')
566					_exit(0);
567				if (crypt_checkpass(clear, pp->pw_passwd) == 0)
568					ok = 1;
569				memset(clear, 0, strlen(clear));
570				if (ok)
571					break;
572				warning("single-user login failed\n");
573			}
574		}
575		endttyent();
576		endpwent();
577#endif /* SECURE */
578
579#ifdef DEBUGSHELL
580		{
581			char altshell[128], *cp = altshell;
582			int num;
583
584#define	SHREQUEST \
585	"Enter pathname of shell or RETURN for sh: "
586
587			(void)write(STDERR_FILENO,
588			    SHREQUEST, sizeof(SHREQUEST) - 1);
589			while ((num = read(STDIN_FILENO, cp, 1)) != -1 &&
590			    num != 0 && *cp != '\n' && cp < &altshell[127])
591				cp++;
592			*cp = '\0';
593
594			/* Copy in alternate shell */
595			if (altshell[0] != '\0'){
596				char *p;
597
598				/* Binary to exec */
599				strlcpy(shell, altshell, sizeof shell);
600
601				/* argv[0] */
602				p = strrchr(altshell, '/');
603				if(p == NULL) p = altshell;
604				else p++;
605
606				name[0] = '-';
607				strlcpy(&name[1], p, sizeof name -1);
608			}
609		}
610#endif /* DEBUGSHELL */
611
612		/*
613		 * Unblock signals.
614		 * We catch all the interesting ones,
615		 * and those are reset to SIG_DFL on exec.
616		 */
617		sigemptyset(&mask);
618		sigprocmask(SIG_SETMASK, &mask, NULL);
619
620		/*
621		 * Fire off a shell.
622		 * If the default one doesn't work, try the Bourne shell.
623		 */
624		argv[0] = name;
625		argv[1] = NULL;
626		setenv("PATH", _PATH_STDPATH, 1);
627		execv(shell, argv);
628		emergency("can't exec %s for single user: %m", shell);
629
630		argv[0] = "-sh";
631		argv[1] = NULL;
632		execv(_PATH_BSHELL, argv);
633		emergency("can't exec %s for single user: %m", _PATH_BSHELL);
634		sleep(STALL_TIMEOUT);
635		_exit(1);
636	}
637
638	if (pid == -1) {
639		/*
640		 * We are seriously hosed.  Do our best.
641		 */
642		emergency("can't fork single-user shell, trying again");
643		while (waitpid(-1, NULL, WNOHANG) > 0)
644			continue;
645		return single_user;
646	}
647
648	requested_transition = 0;
649	do {
650		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
651			collect_child(wpid);
652		if (wpid == -1) {
653			if (errno == EINTR)
654				continue;
655			warning("wait for single-user shell failed: %m; restarting");
656			return single_user;
657		}
658		if (wpid == pid && WIFSTOPPED(status)) {
659			warning("init: shell stopped, restarting\n");
660			kill(pid, SIGCONT);
661			wpid = -1;
662		}
663	} while (wpid != pid && !requested_transition);
664
665	if (requested_transition)
666		return requested_transition;
667
668	if (!WIFEXITED(status)) {
669		if (WTERMSIG(status) == SIGKILL) {
670			/*
671			 *  reboot(8) killed shell?
672			 */
673			warning("single user shell terminated.");
674			sleep(STALL_TIMEOUT);
675			_exit(0);
676		} else {
677			warning("single user shell terminated, restarting");
678			return single_user;
679		}
680	}
681
682	runcom_mode = FASTBOOT;
683	return runcom;
684}
685
686/*
687 * Run the system startup script.
688 */
689state_t
690f_runcom(void)
691{
692	pid_t pid, wpid;
693	int status;
694	char *argv[4];
695	struct sigaction sa;
696
697	if ((pid = fork()) == 0) {
698		memset(&sa, 0, sizeof sa);
699		sigemptyset(&sa.sa_mask);
700		sa.sa_flags = 0;
701		sa.sa_handler = SIG_IGN;
702		(void) sigaction(SIGTSTP, &sa, NULL);
703		(void) sigaction(SIGHUP, &sa, NULL);
704
705		setctty(_PATH_CONSOLE);
706
707		argv[0] = "sh";
708		argv[1] = _PATH_RUNCOM;
709		argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : NULL;
710		argv[3] = NULL;
711
712		sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
713
714		setprocresources(RESOURCE_RC);
715
716		execv(_PATH_BSHELL, argv);
717		stall("can't exec %s for %s: %m", _PATH_BSHELL, _PATH_RUNCOM);
718		_exit(1);	/* force single user mode */
719	}
720
721	if (pid == -1) {
722		emergency("can't fork for %s on %s: %m",
723			_PATH_BSHELL, _PATH_RUNCOM);
724		while (waitpid(-1, NULL, WNOHANG) > 0)
725			continue;
726		sleep(STALL_TIMEOUT);
727		return single_user;
728	}
729
730	/*
731	 * Copied from single_user().  This is a bit paranoid.
732	 */
733	do {
734		if ((wpid = waitpid(-1, &status, WUNTRACED)) != -1)
735			collect_child(wpid);
736		if (wpid == -1) {
737			if (errno == EINTR)
738				continue;
739			warning("wait for %s on %s failed: %m; going to single user mode",
740			    _PATH_BSHELL, _PATH_RUNCOM);
741			return single_user;
742		}
743		if (wpid == pid && WIFSTOPPED(status)) {
744			warning("init: %s on %s stopped, restarting\n",
745			    _PATH_BSHELL, _PATH_RUNCOM);
746			kill(pid, SIGCONT);
747			wpid = -1;
748		}
749	} while (wpid != pid);
750
751	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGTERM &&
752	    requested_transition == catatonia) {
753		/* /etc/rc executed /sbin/reboot; wait for the end quietly */
754		sigset_t s;
755
756		sigfillset(&s);
757		for (;;)
758			sigsuspend(&s);
759	}
760
761	if (!WIFEXITED(status)) {
762		warning("%s on %s terminated abnormally, going to single user mode",
763		    _PATH_BSHELL, _PATH_RUNCOM);
764		return single_user;
765	}
766
767	if (WEXITSTATUS(status))
768		return single_user;
769
770	runcom_mode = AUTOBOOT;		/* the default */
771	/* NB: should send a message to the session logger to avoid blocking. */
772	logwtmp("~", "reboot", "");
773	return read_ttys;
774}
775
776/*
777 * Compare session keys.
778 */
779static int
780cmp_sessions(session_t *sp1, session_t *sp2)
781{
782	if (sp1->se_process < sp2->se_process)
783		return (-1);
784	if (sp1->se_process > sp2->se_process)
785		return (1);
786	return (0);
787}
788
789/*
790 * Add a new login session.
791 */
792void
793add_session(session_t *sp)
794{
795	if (RB_INSERT(session_tree, &session_tree, sp) != NULL)
796		emergency("insert %d: %s", sp->se_process, strerror(errno));
797}
798
799/*
800 * Delete an old login session.
801 */
802void
803del_session(session_t *sp)
804{
805	RB_REMOVE(session_tree, &session_tree, sp);
806}
807
808/*
809 * Look up a login session by pid.
810 */
811session_t *
812find_session(pid_t pid)
813{
814	struct init_session s;
815
816	s.se_process = pid;
817	return (RB_FIND(session_tree, &session_tree, &s));
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 = calloc((strlen(command) + 1) / 2 + 1, sizeof (char *));
828	static const char separators[] = " \t";
829
830	if (argv == NULL)
831		return (0);
832
833	if ((argv[argc++] = strtok(command, separators)) == 0) {
834		free(argv);
835		return (0);
836	}
837	while ((argv[argc++] = strtok(NULL, separators)))
838		continue;
839	return (argv);
840}
841
842/*
843 * Deallocate a session descriptor.
844 */
845void
846free_session(session_t *sp)
847{
848	free(sp->se_device);
849	if (sp->se_getty) {
850		free(sp->se_getty);
851		free(sp->se_getty_argv);
852	}
853	if (sp->se_window) {
854		free(sp->se_window);
855		free(sp->se_window_argv);
856	}
857	free(sp);
858}
859
860/*
861 * Allocate a new session descriptor.
862 */
863session_t *
864new_session(session_t *sprev, int session_index, struct ttyent *typ)
865{
866	session_t *sp;
867
868	if ((typ->ty_status & TTY_ON) == 0 ||
869	    typ->ty_name == 0 ||
870	    typ->ty_getty == 0)
871		return (0);
872
873	sp = calloc(1, sizeof (session_t));
874	if (sp == NULL)
875		err(1, "calloc");
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 = NULL;
889	if (sprev == NULL) {
890		sessions = sp;
891		sp->se_prev = NULL;
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 = NULL;
917		return (0);
918	}
919	if (typ->ty_window) {
920		free(sp->se_window);
921		sp->se_window = strdup(typ->ty_window);
922		if (sp->se_window == NULL) {
923			warning("can't allocate window");
924			return (0);
925		}
926		sp->se_window_argv = construct_argv(sp->se_window);
927		if (sp->se_window_argv == NULL) {
928			warning("can't parse window for port %s",
929			    sp->se_device);
930			free(sp->se_window);
931			sp->se_window = NULL;
932			return (0);
933		}
934	}
935	return (1);
936}
937
938/*
939 * Walk the list of ttys and create sessions for each active line.
940 */
941state_t
942f_read_ttys(void)
943{
944	int session_index = 0;
945	session_t *sp, *snext;
946	struct ttyent *typ;
947
948	/*
949	 * Destroy any previous session state.
950	 * There shouldn't be any, but just in case...
951	 */
952	for (sp = sessions; sp; sp = snext) {
953		if (sp->se_process)
954			clear_session_logs(sp);
955		snext = sp->se_next;
956		free_session(sp);
957	}
958	sessions = NULL;
959
960	/*
961	 * Allocate a session entry for each active port.
962	 * Note that sp starts at 0.
963	 */
964	while ((typ = getttyent()))
965		if ((snext = new_session(sp, ++session_index, typ)))
966			sp = snext;
967
968	endttyent();
969
970	return multi_user;
971}
972
973/*
974 * Start a window system running.
975 */
976void
977start_window_system(session_t *sp)
978{
979	pid_t pid;
980	sigset_t mask;
981
982	if ((pid = fork()) == -1) {
983		emergency("can't fork for window system on port %s: %m",
984		    sp->se_device);
985		/* hope that getty fails and we can try again */
986		return;
987	}
988
989	if (pid)
990		return;
991
992	sigemptyset(&mask);
993	sigprocmask(SIG_SETMASK, &mask, NULL);
994
995	if (setsid() < 0)
996		emergency("setsid failed (window) %m");
997
998	setprocresources(RESOURCE_WINDOW);
999
1000	execv(sp->se_window_argv[0], sp->se_window_argv);
1001	stall("can't exec window system '%s' for port %s: %m",
1002	    sp->se_window_argv[0], sp->se_device);
1003	_exit(1);
1004}
1005
1006/*
1007 * Start a login session running.
1008 * For first open, man-handle tty directly to determine if it
1009 * really exists. It is not efficient to spawn gettys on devices
1010 * that do not exist.
1011 */
1012pid_t
1013start_getty(session_t *sp)
1014{
1015	pid_t pid;
1016	sigset_t mask;
1017	time_t current_time = time(NULL);
1018	int p[2], new = 1;
1019
1020	if (sp->se_flags & SE_DEVEXISTS)
1021		new = 0;
1022
1023	if (new) {
1024		if (pipe(p) == -1)
1025			return (-1);
1026	}
1027
1028	/*
1029	 * fork(), not vfork() -- we can't afford to block.
1030	 */
1031	if ((pid = fork()) == -1) {
1032		emergency("can't fork for getty on port %s: %m", sp->se_device);
1033		return (-1);
1034	}
1035
1036	if (pid) {
1037		if (new) {
1038			char c;
1039
1040			close(p[1]);
1041			if (read(p[0], &c, 1) != 1) {
1042				close(p[0]);
1043				return (-1);
1044			}
1045			close(p[0]);
1046			if (c == '1')
1047				sp->se_flags |= SE_DEVEXISTS;
1048			else
1049				sp->se_flags |= SE_SHUTDOWN;
1050		}
1051		return (pid);
1052	}
1053	if (new) {
1054		int fd;
1055
1056		close(p[0]);
1057		fd = open(sp->se_device, O_RDONLY | O_NONBLOCK, 0666);
1058		if (fd == -1 && (errno == ENXIO || errno == ENOENT ||
1059		    errno == EISDIR)) {
1060			(void)write(p[1], "0", 1);
1061			close(p[1]);
1062			_exit(1);
1063		}
1064		(void)write(p[1], "1", 1);
1065		close(p[1]);
1066		close(fd);
1067		sleep(1);
1068	}
1069
1070	if (current_time > sp->se_started &&
1071	    current_time - sp->se_started < GETTY_SPACING) {
1072		warning("getty repeating too quickly on port %s, sleeping",
1073		    sp->se_device);
1074		sleep(GETTY_SLEEP);
1075	}
1076
1077	if (sp->se_window) {
1078		start_window_system(sp);
1079		sleep(WINDOW_WAIT);
1080	}
1081
1082	sigemptyset(&mask);
1083	sigprocmask(SIG_SETMASK, &mask, NULL);
1084
1085	setprocresources(RESOURCE_GETTY);
1086
1087	execv(sp->se_getty_argv[0], sp->se_getty_argv);
1088	stall("can't exec getty '%s' for port %s: %m",
1089	    sp->se_getty_argv[0], sp->se_device);
1090	_exit(1);
1091}
1092
1093/*
1094 * Collect exit status for a child.
1095 * If an exiting login, start a new login running.
1096 */
1097void
1098collect_child(pid_t pid)
1099{
1100	session_t *sp, *sprev, *snext;
1101
1102	if (sessions == NULL)
1103		return;
1104
1105	if ((sp = find_session(pid)) == NULL)
1106		return;
1107
1108	clear_session_logs(sp);
1109	login_fbtab(sp->se_device + sizeof(_PATH_DEV) - 1, 0, 0);
1110	del_session(sp);
1111	sp->se_process = 0;
1112
1113	if (sp->se_flags & SE_SHUTDOWN) {
1114		if ((sprev = sp->se_prev))
1115			sprev->se_next = sp->se_next;
1116		else
1117			sessions = sp->se_next;
1118		if ((snext = sp->se_next))
1119			snext->se_prev = sp->se_prev;
1120		free_session(sp);
1121		return;
1122	}
1123
1124	if ((pid = start_getty(sp)) == -1) {
1125		/* serious trouble */
1126		requested_transition = clean_ttys;
1127		return;
1128	}
1129
1130	sp->se_process = pid;
1131	sp->se_started = time(NULL);
1132	add_session(sp);
1133}
1134
1135/*
1136 * Catch a signal and request a state transition.
1137 */
1138void
1139transition_handler(int sig)
1140{
1141
1142	switch (sig) {
1143	case SIGHUP:
1144		requested_transition = clean_ttys;
1145		break;
1146	case SIGINT:
1147		requested_transition = do_reboot;
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_t
1171f_multi_user(void)
1172{
1173	pid_t pid;
1174	session_t *sp;
1175
1176	/*
1177	 * If the administrator has not set the security level to -1
1178	 * to indicate that the kernel should not run multiuser in secure
1179	 * mode, and the run script has not set a higher level of security
1180	 * than level 1, then put the kernel into secure mode.
1181	 */
1182	if (requested_transition != catatonia) {
1183		if (getsecuritylevel() == 0)
1184			setsecuritylevel(1);
1185	}
1186
1187	requested_transition = 0;
1188
1189	for (sp = sessions; sp; sp = sp->se_next) {
1190		if (sp->se_process)
1191			continue;
1192		if ((pid = start_getty(sp)) == -1) {
1193			/* serious trouble */
1194			requested_transition = clean_ttys;
1195			break;
1196		}
1197		sp->se_process = pid;
1198		sp->se_started = time(NULL);
1199		add_session(sp);
1200	}
1201
1202	while (!requested_transition)
1203		if ((pid = waitpid(-1, NULL, 0)) != -1)
1204			collect_child(pid);
1205
1206	return requested_transition;
1207}
1208
1209/*
1210 * This is an n-squared algorithm.  We hope it isn't run often...
1211 */
1212state_t
1213f_clean_ttys(void)
1214{
1215	session_t *sp, *sprev;
1216	struct ttyent *typ;
1217	int session_index = 0;
1218	int devlen;
1219
1220	for (sp = sessions; sp; sp = sp->se_next)
1221		sp->se_flags &= ~SE_PRESENT;
1222
1223	devlen = sizeof(_PATH_DEV) - 1;
1224	while ((typ = getttyent())) {
1225		++session_index;
1226
1227		for (sprev = NULL, sp = sessions; sp; sprev = sp, sp = sp->se_next)
1228			if (strcmp(typ->ty_name, sp->se_device + devlen) == 0)
1229				break;
1230
1231		if (sp) {
1232			sp->se_flags |= SE_PRESENT;
1233			if (sp->se_index != session_index) {
1234				warning("port %s changed utmp index from %d to %d",
1235				    sp->se_device, sp->se_index,
1236				    session_index);
1237				sp->se_index = session_index;
1238			}
1239			if ((typ->ty_status & TTY_ON) == 0 ||
1240			    typ->ty_getty == 0) {
1241				sp->se_flags |= SE_SHUTDOWN;
1242				kill(sp->se_process, SIGHUP);
1243				continue;
1244			}
1245			sp->se_flags &= ~SE_SHUTDOWN;
1246			if (setupargv(sp, typ) == 0) {
1247				warning("can't parse getty for port %s",
1248				    sp->se_device);
1249				sp->se_flags |= SE_SHUTDOWN;
1250				kill(sp->se_process, SIGHUP);
1251			}
1252			continue;
1253		}
1254
1255		new_session(sprev, session_index, typ);
1256	}
1257
1258	endttyent();
1259
1260	for (sp = sessions; sp; sp = sp->se_next)
1261		if ((sp->se_flags & SE_PRESENT) == 0) {
1262			sp->se_flags |= SE_SHUTDOWN;
1263			kill(sp->se_process, SIGHUP);
1264		}
1265
1266	return multi_user;
1267}
1268
1269/*
1270 * Block further logins.
1271 */
1272state_t
1273f_catatonia(void)
1274{
1275	session_t *sp;
1276
1277	for (sp = sessions; sp; sp = sp->se_next)
1278		sp->se_flags |= SE_SHUTDOWN;
1279
1280	return multi_user;
1281}
1282
1283/*
1284 * Note SIGALRM.
1285 */
1286void
1287alrm_handler(int sig)
1288{
1289	clang = 1;
1290}
1291
1292int death_howto = RB_HALT;
1293
1294/*
1295 * Reboot the system.
1296 */
1297state_t
1298f_do_reboot(void)
1299{
1300	death_howto = RB_AUTOBOOT;
1301	return nice_death;
1302}
1303
1304/*
1305 * Bring the system down nicely, then we must powerdown because something
1306 * is very wrong.
1307 */
1308state_t
1309f_hard_death(void)
1310{
1311	death_howto |= RB_POWERDOWN;
1312	return nice_death;
1313}
1314
1315/*
1316 * Bring the system down to single user nicely, after run the shutdown script.
1317 */
1318state_t
1319f_nice_death(void)
1320{
1321	session_t *sp;
1322	int i;
1323	pid_t pid;
1324	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1325	int status;
1326
1327#ifdef CPU_LIDSUSPEND
1328	int mib[] = {CTL_MACHDEP, CPU_LIDACTION};
1329	int lidaction = 0;
1330
1331	if ((death_howto & RB_POWERDOWN) &&
1332	    (sysctl(mib, 2, NULL, NULL, &lidaction,
1333		    sizeof(lidaction)) == -1) && (errno != EOPNOTSUPP))
1334			warning("cannot disable lid action");
1335#endif
1336
1337	for (sp = sessions; sp; sp = sp->se_next) {
1338		sp->se_flags &= ~SE_PRESENT;
1339		sp->se_flags |= SE_SHUTDOWN;
1340		kill(sp->se_process, SIGHUP);
1341	}
1342
1343	/* terminate the accounting process */
1344	acct(NULL);
1345
1346	/* NB: should send a message to the session logger to avoid blocking. */
1347	logwtmp("~", "shutdown", "");
1348
1349	if (access(_PATH_RUNCOM, R_OK) != -1) {
1350		struct sigaction sa;
1351
1352		switch ((pid = fork())) {
1353		case -1:
1354			break;
1355		case 0:
1356
1357			memset(&sa, 0, sizeof sa);
1358			sigemptyset(&sa.sa_mask);
1359			sa.sa_flags = 0;
1360			sa.sa_handler = SIG_IGN;
1361			(void) sigaction(SIGTSTP, &sa, NULL);
1362			(void) sigaction(SIGHUP, &sa, NULL);
1363
1364			setctty(_PATH_CONSOLE);
1365
1366			sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
1367
1368			execl(_PATH_BSHELL, "sh", _PATH_RUNCOM, "shutdown",
1369			    (char *)NULL);
1370			stall("can't exec %s for %s %s: %m", _PATH_BSHELL,
1371			    _PATH_RUNCOM, "shutdown");
1372			_exit(1);
1373		default:
1374			waitpid(pid, &status, 0);
1375			if (WIFEXITED(status) && WEXITSTATUS(status) == 2)
1376				death_howto |= RB_POWERDOWN;
1377		}
1378	}
1379
1380	for (i = 0; i < 3; ++i) {
1381		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1382			goto die;
1383
1384		clang = 0;
1385		alarm(DEATH_WATCH);
1386		do {
1387			if ((pid = waitpid(-1, NULL, 0)) != -1)
1388				collect_child(pid);
1389		} while (clang == 0 && errno != ECHILD);
1390
1391		if (errno == ECHILD)
1392			goto die;
1393	}
1394
1395	warning("some processes would not die; ps axl advised");
1396
1397die:
1398	reboot(death_howto);
1399
1400	/* ... and if that fails.. oh well */
1401	return single_user;
1402}
1403
1404/*
1405 * Bring the system down to single user.
1406 */
1407state_t
1408f_death(void)
1409{
1410	session_t *sp;
1411	int i;
1412	pid_t pid;
1413	static const int death_sigs[3] = { SIGHUP, SIGTERM, SIGKILL };
1414
1415	/* terminate the accounting process */
1416	acct(NULL);
1417
1418	for (sp = sessions; sp; sp = sp->se_next)
1419		sp->se_flags |= SE_SHUTDOWN;
1420
1421	/* NB: should send a message to the session logger to avoid blocking. */
1422	logwtmp("~", "shutdown", "");
1423
1424	for (i = 0; i < 3; ++i) {
1425		if (kill(-1, death_sigs[i]) == -1 && errno == ESRCH)
1426			return single_user;
1427
1428		clang = 0;
1429		alarm(DEATH_WATCH);
1430		do {
1431			if ((pid = waitpid(-1, NULL, 0)) != -1)
1432				collect_child(pid);
1433		} while (clang == 0 && errno != ECHILD);
1434
1435		if (errno == ECHILD)
1436			return single_user;
1437	}
1438
1439	warning("some processes would not die; ps axl advised");
1440
1441	return single_user;
1442}
1443
1444#ifdef LOGIN_CAP
1445void
1446setprocresources(char *class)
1447{
1448	login_cap_t *lc;
1449
1450	if ((lc = login_getclass(class)) != NULL) {
1451		setusercontext(lc, NULL, 0,
1452		    LOGIN_SETPRIORITY|LOGIN_SETRESOURCES|LOGIN_SETUMASK);
1453		login_close(lc);
1454	}
1455}
1456#endif
1457