1/*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 * Copyright (c) 2002 Networks Associates Technologies, Inc.
7 * All rights reserved.
8 *
9 * Portions of this software were developed for the FreeBSD Project by
10 * ThinkSec AS and NAI Labs, the Security Research Division of Network
11 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
12 * ("CBOSS"), as part of the DARPA CHATS research program.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 *    must display the following acknowledgement:
24 *	This product includes software developed by the University of
25 *	California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 *    may be used to endorse or promote products derived from this software
28 *    without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 */
42
43#include <sys/cdefs.h>
44/*
45 * login [ name ]
46 * login -h hostname	(for telnetd, etc.)
47 * login -f name	(for pre-authenticated login: datakit, xterm, etc.)
48 */
49
50#include <sys/param.h>
51#include <sys/file.h>
52#include <sys/stat.h>
53#include <sys/time.h>
54#include <sys/resource.h>
55#include <sys/wait.h>
56
57#include <err.h>
58#include <errno.h>
59#include <grp.h>
60#include <login_cap.h>
61#include <pwd.h>
62#include <setjmp.h>
63#include <signal.h>
64#include <stdio.h>
65#include <stdlib.h>
66#include <string.h>
67#include <syslog.h>
68#include <ttyent.h>
69#include <unistd.h>
70
71#include <security/pam_appl.h>
72#include <security/openpam.h>
73
74#include "login.h"
75#include "pathnames.h"
76
77static int		 auth_pam(void);
78static void		 bail(int, int);
79static void		 bail_internal(int, int, int);
80static int		 export(const char *);
81static void		 export_pam_environment(void);
82static int		 motd(const char *);
83static void		 badlogin(char *);
84static char		*getloginname(void);
85static void		 pam_syslog(const char *);
86static void		 pam_cleanup(void);
87static void		 refused(const char *, const char *, int);
88static const char	*stypeof(char *);
89static void		 sigint(int);
90static void		 timedout(int);
91static void		 bail_sig(int);
92static void		 usage(void);
93
94#define	TTYGRPNAME		"tty"			/* group to own ttys */
95#define	DEFAULT_BACKOFF		3
96#define	DEFAULT_RETRIES		10
97#define	DEFAULT_PROMPT		"login: "
98#define	DEFAULT_PASSWD_PROMPT	"Password:"
99#define	TERM_UNKNOWN		"su"
100#define	DEFAULT_WARN		(2L * 7L * 86400L)	/* Two weeks */
101#define	NO_SLEEP_EXIT		0
102#define	SLEEP_EXIT		5
103
104/*
105 * This bounds the time given to login.  Not a define so it can
106 * be patched on machines where it's too small.
107 */
108static u_int		timeout = 300;
109
110/* Buffer for signal handling of timeout */
111static jmp_buf		 timeout_buf;
112
113char			 pwbuf[1024];
114struct passwd		 pwres;
115struct passwd		*pwd;
116static int		 failures;
117
118static char		*envinit[1];	/* empty environment list */
119
120/*
121 * Command line flags and arguments
122 */
123static int		 fflag;		/* -f: do not perform authentication */
124static int		 hflag;		/* -h: login from remote host */
125static char		*hostname;	/* hostname from command line */
126static int		 pflag;		/* -p: preserve environment */
127
128/*
129 * User name
130 */
131static char		*username;	/* user name */
132static char		*olduser;	/* previous user name */
133
134/*
135 * Prompts
136 */
137static char		 default_prompt[] = DEFAULT_PROMPT;
138static const char	*prompt;
139static char		 default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT;
140static const char	*passwd_prompt;
141
142static char		*tty;
143
144/*
145 * PAM data
146 */
147static pam_handle_t	*pamh = NULL;
148static struct pam_conv	 pamc = { openpam_ttyconv, NULL };
149static int		 pam_err;
150static int		 pam_silent = PAM_SILENT;
151static int		 pam_cred_established;
152static int		 pam_session_established;
153
154int
155main(int argc, char *argv[])
156{
157	struct group *gr;
158	struct stat st;
159	int retries, backoff;
160	int ask, ch, cnt, quietlog, rootlogin, rval;
161	uid_t uid, euid;
162	gid_t egid;
163	char *term;
164	char *p, *ttyn;
165	char tname[sizeof(_PATH_TTY) + 10];
166	char *arg0;
167	const char *tp;
168	const char *shell = NULL;
169	login_cap_t *lc = NULL;
170	login_cap_t *lc_user = NULL;
171	pid_t pid;
172	sigset_t mask, omask;
173	struct sigaction sa;
174#ifdef USE_BSM_AUDIT
175	char auditsuccess = 1;
176#endif
177
178	sa.sa_flags = SA_RESTART;
179	(void)sigfillset(&sa.sa_mask);
180	sa.sa_handler = SIG_IGN;
181	(void)sigaction(SIGQUIT, &sa, NULL);
182	(void)sigaction(SIGINT, &sa, NULL);
183	(void)sigaction(SIGHUP, &sa, NULL);
184	if (setjmp(timeout_buf)) {
185		if (failures)
186			badlogin(username);
187		(void)fprintf(stderr, "Login timed out after %d seconds\n",
188		    timeout);
189		bail(NO_SLEEP_EXIT, 0);
190	}
191	sa.sa_handler = timedout;
192	(void)sigaction(SIGALRM, &sa, NULL);
193	(void)alarm(timeout);
194	(void)setpriority(PRIO_PROCESS, 0, 0);
195
196	openlog("login", LOG_CONS, LOG_AUTH);
197
198	uid = getuid();
199	euid = geteuid();
200	egid = getegid();
201
202	while ((ch = getopt(argc, argv, "fh:p")) != -1)
203		switch (ch) {
204		case 'f':
205			fflag = 1;
206			break;
207		case 'h':
208			if (uid != 0)
209				errx(1, "-h option: %s", strerror(EPERM));
210			if (strlen(optarg) >= MAXHOSTNAMELEN)
211				errx(1, "-h option: %s: exceeds maximum "
212				    "hostname size", optarg);
213			hflag = 1;
214			hostname = optarg;
215			break;
216		case 'p':
217			pflag = 1;
218			break;
219		case '?':
220		default:
221			if (uid == 0)
222				syslog(LOG_ERR, "invalid flag %c", ch);
223			usage();
224		}
225	argc -= optind;
226	argv += optind;
227
228	if (argc > 0) {
229		username = strdup(*argv);
230		if (username == NULL)
231			err(1, "strdup()");
232		ask = 0;
233	} else {
234		ask = 1;
235	}
236
237	setproctitle("-%s", getprogname());
238
239	closefrom(3);
240
241	/*
242	 * Get current TTY
243	 */
244	ttyn = ttyname(STDIN_FILENO);
245	if (ttyn == NULL || *ttyn == '\0') {
246		(void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY);
247		ttyn = tname;
248	}
249	if (strncmp(ttyn, _PATH_DEV, sizeof _PATH_DEV - 1) == 0)
250		tty = ttyn + sizeof _PATH_DEV - 1;
251	else
252		tty = ttyn;
253
254	/*
255	 * Get "login-retries" & "login-backoff" from default class
256	 */
257	lc = login_getclass(NULL);
258	prompt = login_getcapstr(lc, "login_prompt",
259	    default_prompt, default_prompt);
260	passwd_prompt = login_getcapstr(lc, "passwd_prompt",
261	    default_passwd_prompt, default_passwd_prompt);
262	retries = login_getcapnum(lc, "login-retries",
263	    DEFAULT_RETRIES, DEFAULT_RETRIES);
264	backoff = login_getcapnum(lc, "login-backoff",
265	    DEFAULT_BACKOFF, DEFAULT_BACKOFF);
266	login_close(lc);
267	lc = NULL;
268
269	/*
270	 * Try to authenticate the user until we succeed or time out.
271	 */
272	for (cnt = 0;; ask = 1) {
273		if (ask) {
274			fflag = 0;
275			if (olduser != NULL)
276				free(olduser);
277			olduser = username;
278			username = getloginname();
279		}
280		rootlogin = 0;
281
282		/*
283		 * Note if trying multiple user names; log failures for
284		 * previous user name, but don't bother logging one failure
285		 * for nonexistent name (mistyped username).
286		 */
287		if (failures && strcmp(olduser, username) != 0) {
288			if (failures > (pwd ? 0 : 1))
289				badlogin(olduser);
290		}
291
292		/*
293		 * Load the PAM policy and set some variables
294		 */
295		pam_err = pam_start("login", username, &pamc, &pamh);
296		if (pam_err != PAM_SUCCESS) {
297			pam_syslog("pam_start()");
298#ifdef USE_BSM_AUDIT
299			au_login_fail("PAM Error", 1);
300#endif
301			bail(NO_SLEEP_EXIT, 1);
302		}
303		pam_err = pam_set_item(pamh, PAM_TTY, tty);
304		if (pam_err != PAM_SUCCESS) {
305			pam_syslog("pam_set_item(PAM_TTY)");
306#ifdef USE_BSM_AUDIT
307			au_login_fail("PAM Error", 1);
308#endif
309			bail(NO_SLEEP_EXIT, 1);
310		}
311		pam_err = pam_set_item(pamh, PAM_RHOST, hostname);
312		if (pam_err != PAM_SUCCESS) {
313			pam_syslog("pam_set_item(PAM_RHOST)");
314#ifdef USE_BSM_AUDIT
315			au_login_fail("PAM Error", 1);
316#endif
317			bail(NO_SLEEP_EXIT, 1);
318		}
319
320		(void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), &pwd);
321		if (pwd != NULL && pwd->pw_uid == 0)
322			rootlogin = 1;
323
324		/*
325		 * If the -f option was specified and the caller is
326		 * root or the caller isn't changing their uid, don't
327		 * authenticate.
328		 */
329		if (pwd != NULL && fflag &&
330		    (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) {
331			/* already authenticated */
332			rval = 0;
333#ifdef USE_BSM_AUDIT
334			auditsuccess = 0; /* opened a terminal window only */
335#endif
336		} else {
337			fflag = 0;
338			(void)setpriority(PRIO_PROCESS, 0, -4);
339			rval = auth_pam();
340			(void)setpriority(PRIO_PROCESS, 0, 0);
341		}
342
343		if (pwd != NULL && rval == 0)
344			break;
345
346		pam_cleanup();
347
348		/*
349		 * We are not exiting here, but this corresponds to a failed
350		 * login event, so set exitstatus to 1.
351		 */
352#ifdef USE_BSM_AUDIT
353		au_login_fail("Login incorrect", 1);
354#endif
355
356		(void)printf("Login incorrect\n");
357		failures++;
358
359		pwd = NULL;
360
361		/*
362		 * Allow up to 'retry' (10) attempts, but start
363		 * backing off after 'backoff' (3) attempts.
364		 */
365		if (++cnt > backoff) {
366			if (cnt >= retries) {
367				badlogin(username);
368				bail(SLEEP_EXIT, 1);
369			}
370			sleep((u_int)((cnt - backoff) * 5));
371		}
372	}
373
374	/* committed to login -- turn off timeout */
375	(void)alarm((u_int)0);
376
377	(void)sigemptyset(&mask);
378	(void)sigaddset(&mask, SIGHUP);
379	(void)sigaddset(&mask, SIGTERM);
380	(void)sigprocmask(SIG_BLOCK, &mask, &omask);
381	sa.sa_handler = bail_sig;
382	(void)sigaction(SIGHUP, &sa, NULL);
383	(void)sigaction(SIGTERM, &sa, NULL);
384
385	endpwent();
386
387#ifdef USE_BSM_AUDIT
388	/* Audit successful login. */
389	if (auditsuccess)
390		au_login_success();
391#endif
392
393	/*
394	 * This needs to happen before login_getpwclass to support
395	 * home directories on GSS-API authenticated NFS where the
396	 * kerberos credentials need to be saved so that the kernel
397	 * can authenticate to the NFS server.
398	 */
399	pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED);
400	if (pam_err != PAM_SUCCESS) {
401		pam_syslog("pam_setcred()");
402		bail(NO_SLEEP_EXIT, 1);
403	}
404	pam_cred_established = 1;
405
406	/*
407	 * Establish the login class.
408	 */
409	lc = login_getpwclass(pwd);
410	lc_user = login_getuserclass(pwd);
411
412	if (!(quietlog = login_getcapbool(lc_user, "hushlogin", 0)))
413		quietlog = login_getcapbool(lc, "hushlogin", 0);
414
415	/*
416	 * Switching needed for NFS with root access disabled.
417	 *
418	 * XXX: This change fails to modify the additional groups for the
419	 * process, and as such, may restrict rights normally granted
420	 * through those groups.
421	 */
422	(void)setegid(pwd->pw_gid);
423	(void)seteuid(rootlogin ? 0 : pwd->pw_uid);
424	if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) {
425		if (login_getcapbool(lc, "requirehome", 0))
426			refused("Home directory not available", "HOMEDIR", 1);
427		if (chdir("/") < 0)
428			refused("Cannot find root directory", "ROOTDIR", 1);
429		if (!quietlog || *pwd->pw_dir)
430			printf("No home directory.\nLogging in with home = \"/\".\n");
431		pwd->pw_dir = strdup("/");
432		if (pwd->pw_dir == NULL) {
433			syslog(LOG_NOTICE, "strdup(): %m");
434			bail(SLEEP_EXIT, 1);
435		}
436	}
437	(void)seteuid(euid);
438	(void)setegid(egid);
439	if (!quietlog) {
440		quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;
441		if (!quietlog)
442			pam_silent = 0;
443	}
444
445	shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell);
446	if (*pwd->pw_shell == '\0')
447		pwd->pw_shell = strdup(_PATH_BSHELL);
448	if (pwd->pw_shell == NULL) {
449		syslog(LOG_NOTICE, "strdup(): %m");
450		bail(SLEEP_EXIT, 1);
451	}
452	if (*shell == '\0')   /* Not overridden */
453		shell = pwd->pw_shell;
454	if ((shell = strdup(shell)) == NULL) {
455		syslog(LOG_NOTICE, "strdup(): %m");
456		bail(SLEEP_EXIT, 1);
457	}
458
459	/*
460	 * Set device protections, depending on what terminal the
461	 * user is logged in. This feature is used on Suns to give
462	 * console users better privacy.
463	 */
464	login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);
465
466	/*
467	 * Clear flags of the tty.  None should be set, and when the
468	 * user sets them otherwise, this can cause the chown to fail.
469	 * Since it isn't clear that flags are useful on character
470	 * devices, we just clear them.
471	 *
472	 * We don't log in the case of EOPNOTSUPP because dev might be
473	 * on NFS, which doesn't support chflags.
474	 *
475	 * We don't log in the EROFS because that means that /dev is on
476	 * a read only file system and we assume that the permissions there
477	 * are sane.
478	 */
479	if (ttyn != tname && chflags(ttyn, 0))
480		if (errno != EOPNOTSUPP && errno != EROFS)
481			syslog(LOG_ERR, "chflags(%s): %m", ttyn);
482	if (ttyn != tname && chown(ttyn, pwd->pw_uid,
483	    (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid))
484		if (errno != EROFS)
485			syslog(LOG_ERR, "chown(%s): %m", ttyn);
486
487#ifdef LOGALL
488	/*
489	 * Syslog each successful login, so we don't have to watch
490	 * hundreds of wtmp or lastlogin files.
491	 */
492	if (hflag)
493		syslog(LOG_INFO, "login from %s on %s as %s",
494		       hostname, tty, pwd->pw_name);
495	else
496		syslog(LOG_INFO, "login on %s as %s",
497		       tty, pwd->pw_name);
498#endif
499
500	/*
501	 * If fflag is on, assume caller/authenticator has logged root
502	 * login.
503	 */
504	if (rootlogin && fflag == 0) {
505		if (hflag)
506			syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s",
507			    username, tty, hostname);
508		else
509			syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s",
510			    username, tty);
511	}
512
513	/*
514	 * Destroy environment unless user has requested its
515	 * preservation - but preserve TERM in all cases
516	 */
517	term = getenv("TERM");
518	if (!pflag)
519		environ = envinit;
520	if (term != NULL)
521		setenv("TERM", term, 0);
522
523	/*
524	 * PAM modules might add supplementary groups during pam_setcred().
525	 */
526	if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) {
527		syslog(LOG_ERR, "setusercontext() failed - exiting");
528		bail(NO_SLEEP_EXIT, 1);
529	}
530
531	pam_err = pam_setcred(pamh, pam_silent|PAM_REINITIALIZE_CRED);
532	if (pam_err != PAM_SUCCESS) {
533		pam_syslog("pam_setcred()");
534		bail(NO_SLEEP_EXIT, 1);
535	}
536
537	pam_err = pam_open_session(pamh, pam_silent);
538	if (pam_err != PAM_SUCCESS) {
539		pam_syslog("pam_open_session()");
540		bail(NO_SLEEP_EXIT, 1);
541	}
542	pam_session_established = 1;
543
544	/*
545	 * We must fork() before setuid() because we need to call
546	 * pam_close_session() as root.
547	 */
548	pid = fork();
549	if (pid < 0) {
550		err(1, "fork");
551	} else if (pid != 0) {
552		/*
553		 * Parent: wait for child to finish, then clean up
554		 * session.
555		 *
556		 * If we get SIGHUP or SIGTERM, clean up the session
557		 * and exit right away. This will make the terminal
558		 * inaccessible and send SIGHUP to the foreground
559		 * process group.
560		 */
561		int status;
562		setproctitle("-%s [pam]", getprogname());
563		(void)sigprocmask(SIG_SETMASK, &omask, NULL);
564		waitpid(pid, &status, 0);
565		(void)sigprocmask(SIG_BLOCK, &mask, NULL);
566		bail(NO_SLEEP_EXIT, 0);
567	}
568
569	/*
570	 * NOTICE: We are now in the child process!
571	 */
572
573	/*
574	 * Add any environment variables the PAM modules may have set.
575	 */
576	export_pam_environment();
577
578	/*
579	 * We're done with PAM now; our parent will deal with the rest.
580	 */
581	pam_end(pamh, 0);
582	pamh = NULL;
583
584	/*
585	 * We don't need to be root anymore, so set the login name and
586	 * the UID.
587	 */
588	if (setlogin(username) != 0) {
589		syslog(LOG_ERR, "setlogin(%s): %m - exiting", username);
590		bail(NO_SLEEP_EXIT, 1);
591	}
592	if (setusercontext(lc, pwd, pwd->pw_uid,
593	    LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) {
594		syslog(LOG_ERR, "setusercontext() failed - exiting");
595		exit(1);
596	}
597
598	(void)setenv("SHELL", pwd->pw_shell, 1);
599	(void)setenv("HOME", pwd->pw_dir, 1);
600	/* Overwrite "term" from login.conf(5) for any known TERM */
601	if (term == NULL && (tp = stypeof(tty)) != NULL)
602		(void)setenv("TERM", tp, 1);
603	else
604		(void)setenv("TERM", TERM_UNKNOWN, 0);
605	(void)setenv("LOGNAME", username, 1);
606	(void)setenv("USER", username, 1);
607	(void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0);
608
609	if (!quietlog) {
610		const char *cw;
611
612		cw = login_getcapstr(lc, "welcome", NULL, NULL);
613		if (cw != NULL && access(cw, F_OK) == 0)
614			motd(cw);
615		else
616			motd(_PATH_MOTDFILE);
617
618		if (login_getcapbool(lc_user, "nocheckmail", 0) == 0 &&
619		    login_getcapbool(lc, "nocheckmail", 0) == 0) {
620			char *cx;
621
622			/* $MAIL may have been set by class. */
623			cx = getenv("MAIL");
624			if (cx == NULL) {
625				asprintf(&cx, "%s/%s",
626				    _PATH_MAILDIR, pwd->pw_name);
627			}
628			if (cx && stat(cx, &st) == 0 && st.st_size != 0)
629				(void)printf("You have %smail.\n",
630				    (st.st_mtime > st.st_atime) ? "new " : "");
631			if (getenv("MAIL") == NULL)
632				free(cx);
633		}
634	}
635
636	login_close(lc_user);
637	login_close(lc);
638
639	sa.sa_handler = SIG_DFL;
640	(void)sigaction(SIGALRM, &sa, NULL);
641	(void)sigaction(SIGQUIT, &sa, NULL);
642	(void)sigaction(SIGINT, &sa, NULL);
643	(void)sigaction(SIGTERM, &sa, NULL);
644	(void)sigaction(SIGHUP, &sa, NULL);
645	sa.sa_handler = SIG_IGN;
646	(void)sigaction(SIGTSTP, &sa, NULL);
647	(void)sigprocmask(SIG_SETMASK, &omask, NULL);
648
649	/*
650	 * Login shells have a leading '-' in front of argv[0]
651	 */
652	p = strrchr(pwd->pw_shell, '/');
653	if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) {
654		syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size",
655		    username);
656		errx(1, "shell exceeds maximum pathname size");
657	} else if (arg0 == NULL) {
658		err(1, "asprintf()");
659	}
660
661	execlp(shell, arg0, (char *)0);
662	err(1, "%s", shell);
663
664	/*
665	 * That's it, folks!
666	 */
667}
668
669/*
670 * Attempt to authenticate the user using PAM.  Returns 0 if the user is
671 * authenticated, or 1 if not authenticated.  If some sort of PAM system
672 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this
673 * function returns -1.  This can be used as an indication that we should
674 * fall back to a different authentication mechanism.
675 */
676static int
677auth_pam(void)
678{
679	const char *tmpl_user;
680	const void *item;
681	int rval;
682
683	pam_err = pam_authenticate(pamh, pam_silent);
684	switch (pam_err) {
685
686	case PAM_SUCCESS:
687		/*
688		 * With PAM we support the concept of a "template"
689		 * user.  The user enters a login name which is
690		 * authenticated by PAM, usually via a remote service
691		 * such as RADIUS or TACACS+.  If authentication
692		 * succeeds, a different but related "template" name
693		 * is used for setting the credentials, shell, and
694		 * home directory.  The name the user enters need only
695		 * exist on the remote authentication server, but the
696		 * template name must be present in the local password
697		 * database.
698		 *
699		 * This is supported by two various mechanisms in the
700		 * individual modules.  However, from the application's
701		 * point of view, the template user is always passed
702		 * back as a changed value of the PAM_USER item.
703		 */
704		pam_err = pam_get_item(pamh, PAM_USER, &item);
705		if (pam_err == PAM_SUCCESS) {
706			tmpl_user = (const char *)item;
707			if (strcmp(username, tmpl_user) != 0) {
708				(void)getpwnam_r(tmpl_user, &pwres, pwbuf,
709				    sizeof(pwbuf), &pwd);
710			}
711		} else {
712			pam_syslog("pam_get_item(PAM_USER)");
713		}
714		rval = 0;
715		break;
716
717	case PAM_AUTH_ERR:
718	case PAM_USER_UNKNOWN:
719	case PAM_MAXTRIES:
720		rval = 1;
721		break;
722
723	default:
724		pam_syslog("pam_authenticate()");
725		rval = -1;
726		break;
727	}
728
729	if (rval == 0) {
730		pam_err = pam_acct_mgmt(pamh, pam_silent);
731		switch (pam_err) {
732		case PAM_SUCCESS:
733			break;
734		case PAM_NEW_AUTHTOK_REQD:
735			pam_err = pam_chauthtok(pamh,
736			    pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK);
737			if (pam_err != PAM_SUCCESS) {
738				pam_syslog("pam_chauthtok()");
739				rval = 1;
740			}
741			break;
742		default:
743			pam_syslog("pam_acct_mgmt()");
744			rval = 1;
745			break;
746		}
747	}
748
749	if (rval != 0) {
750		pam_end(pamh, pam_err);
751		pamh = NULL;
752	}
753	return (rval);
754}
755
756/*
757 * Export any environment variables PAM modules may have set
758 */
759static void
760export_pam_environment(void)
761{
762	char **pam_env;
763	char **pp;
764
765	pam_env = pam_getenvlist(pamh);
766	if (pam_env != NULL) {
767		for (pp = pam_env; *pp != NULL; pp++) {
768			(void)export(*pp);
769			free(*pp);
770		}
771	}
772}
773
774/*
775 * Perform sanity checks on an environment variable:
776 * - Make sure there is an '=' in the string.
777 * - Make sure the string doesn't run on too long.
778 * - Do not export certain variables.  This list was taken from the
779 *   Solaris pam_putenv(3) man page.
780 * Then export it.
781 */
782static int
783export(const char *s)
784{
785	static const char *noexport[] = {
786		"SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
787		"IFS", "PATH", NULL
788	};
789	char *p;
790	const char **pp;
791	size_t n;
792	int rv;
793
794	if (strlen(s) > 1024 || (p = strchr(s, '=')) == NULL)
795		return (0);
796	if (strncmp(s, "LD_", 3) == 0)
797		return (0);
798	for (pp = noexport; *pp != NULL; pp++) {
799		n = strlen(*pp);
800		if (s[n] == '=' && strncmp(s, *pp, n) == 0)
801			return (0);
802	}
803	*p = '\0';
804	rv = setenv(s, p + 1, 1);
805	*p = '=';
806	if (rv == -1)
807		return (0);
808	return (1);
809}
810
811static void
812usage(void)
813{
814
815	(void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n");
816	exit(1);
817}
818
819/*
820 * Prompt user and read login name from stdin.
821 */
822static char *
823getloginname(void)
824{
825	char *nbuf, *p;
826	int ch;
827
828	nbuf = malloc(MAXLOGNAME);
829	if (nbuf == NULL)
830		err(1, "malloc()");
831	do {
832		(void)printf("%s", prompt);
833		for (p = nbuf; (ch = getchar()) != '\n'; ) {
834			if (ch == EOF) {
835				badlogin(username);
836				bail(NO_SLEEP_EXIT, 0);
837			}
838			if (p < nbuf + MAXLOGNAME - 1)
839				*p++ = ch;
840		}
841	} while (p == nbuf);
842
843	*p = '\0';
844	if (nbuf[0] == '-') {
845		pam_silent = 0;
846		memmove(nbuf, nbuf + 1, strlen(nbuf));
847	} else {
848		pam_silent = PAM_SILENT;
849	}
850	return nbuf;
851}
852
853/*
854 * SIGINT handler for motd().
855 */
856static volatile int motdinterrupt;
857static void
858sigint(int signo __unused)
859{
860	motdinterrupt = 1;
861}
862
863/*
864 * Display the contents of a file (such as /etc/motd).
865 */
866static int
867motd(const char *motdfile)
868{
869	struct sigaction newint, oldint;
870	FILE *f;
871	int ch;
872
873	if ((f = fopen(motdfile, "r")) == NULL)
874		return (-1);
875	motdinterrupt = 0;
876	newint.sa_handler = sigint;
877	newint.sa_flags = 0;
878	sigfillset(&newint.sa_mask);
879	sigaction(SIGINT, &newint, &oldint);
880	while ((ch = fgetc(f)) != EOF && !motdinterrupt)
881		putchar(ch);
882	sigaction(SIGINT, &oldint, NULL);
883	if (ch != EOF || ferror(f)) {
884		fclose(f);
885		return (-1);
886	}
887	fclose(f);
888	return (0);
889}
890
891/*
892 * SIGALRM handler, to enforce login prompt timeout.
893 *
894 * XXX This can potentially confuse the hell out of PAM.  We should
895 * XXX instead implement a conversation function that returns
896 * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal
897 * XXX handler just set a flag.
898 */
899static void
900timedout(int signo __unused)
901{
902
903	longjmp(timeout_buf, signo);
904}
905
906static void
907badlogin(char *name)
908{
909
910	if (failures == 0)
911		return;
912	if (hflag) {
913		syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s",
914		    failures, failures > 1 ? "S" : "", hostname);
915		syslog(LOG_AUTHPRIV|LOG_NOTICE,
916		    "%d LOGIN FAILURE%s FROM %s, %s",
917		    failures, failures > 1 ? "S" : "", hostname, name);
918	} else {
919		syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s",
920		    failures, failures > 1 ? "S" : "", tty);
921		syslog(LOG_AUTHPRIV|LOG_NOTICE,
922		    "%d LOGIN FAILURE%s ON %s, %s",
923		    failures, failures > 1 ? "S" : "", tty, name);
924	}
925	failures = 0;
926}
927
928const char *
929stypeof(char *ttyid)
930{
931	struct ttyent *t;
932
933	if (ttyid != NULL && *ttyid != '\0') {
934		t = getttynam(ttyid);
935		if (t != NULL && t->ty_type != NULL)
936			return (t->ty_type);
937	}
938	return (NULL);
939}
940
941static void
942refused(const char *msg, const char *rtype, int lout)
943{
944
945	if (msg != NULL)
946	    printf("%s.\n", msg);
947	if (hflag)
948		syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s",
949		    pwd->pw_name, rtype, hostname, tty);
950	else
951		syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s",
952		    pwd->pw_name, rtype, tty);
953	if (lout)
954		bail(SLEEP_EXIT, 1);
955}
956
957/*
958 * Log a PAM error
959 */
960static void
961pam_syslog(const char *msg)
962{
963	syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err));
964}
965
966/*
967 * Shut down PAM
968 */
969static void
970pam_cleanup(void)
971{
972
973	if (pamh != NULL) {
974		if (pam_session_established) {
975			pam_err = pam_close_session(pamh, 0);
976			if (pam_err != PAM_SUCCESS)
977				pam_syslog("pam_close_session()");
978		}
979		pam_session_established = 0;
980		if (pam_cred_established) {
981			pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED);
982			if (pam_err != PAM_SUCCESS)
983				pam_syslog("pam_setcred()");
984		}
985		pam_cred_established = 0;
986		pam_end(pamh, pam_err);
987		pamh = NULL;
988	}
989}
990
991static void
992bail_internal(int sec, int eval, int signo)
993{
994	struct sigaction sa;
995
996	pam_cleanup();
997#ifdef USE_BSM_AUDIT
998	if (pwd != NULL)
999		audit_logout();
1000#endif
1001	(void)sleep(sec);
1002	if (signo == 0)
1003		exit(eval);
1004	else {
1005		sa.sa_handler = SIG_DFL;
1006		sa.sa_flags = 0;
1007		(void)sigemptyset(&sa.sa_mask);
1008		(void)sigaction(signo, &sa, NULL);
1009		(void)sigaddset(&sa.sa_mask, signo);
1010		(void)sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL);
1011		raise(signo);
1012		exit(128 + signo);
1013	}
1014}
1015
1016/*
1017 * Exit, optionally after sleeping a few seconds
1018 */
1019static void
1020bail(int sec, int eval)
1021{
1022	bail_internal(sec, eval, 0);
1023}
1024
1025/*
1026 * Exit because of a signal.
1027 * This is not async-signal safe, so only call async-signal safe functions
1028 * while the signal is unmasked.
1029 */
1030static void
1031bail_sig(int signo)
1032{
1033	bail_internal(NO_SLEEP_EXIT, 0, signo);
1034}
1035