xref: /src/usr.bin/login/login.c

/*-
 * Copyright (c) 1980, 1987, 1988, 1991 The Regents of the University
 * of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1980, 1987, 1988, 1991 The Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)login.c	5.73 (Berkeley) 6/29/91";
#endif /* not lint */

/*
 * login [ name ]
 * login -h hostname	(for telnetd, etc.)
 * login -f name	(for pre-authenticated login: datakit, xterm, etc.)
 */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/file.h>

#include <utmp.h>
#include <signal.h>
#include <errno.h>
#include <ttyent.h>
#include <syslog.h>
#include <grp.h>
#include <pwd.h>
#include <setjmp.h>
#include <stdio.h>
#include <string.h>
#include <tzfile.h>
#include "pathnames.h"

#define	TTYGRPNAME	"tty"		/* name of group to own ttys */

/*
 * This bounds the time given to login.  Not a define so it can
 * be patched on machines where it's too small.
 */
int	timeout = 300;
int	rootlogin;
#ifdef KERBEROS
int	notickets = 1;
char	*instance;
char	*krbtkfile_env;
int	authok;
#endif

struct	passwd *pwd;
int	failures;
char	term[64], *envinit[1], *hostname, *username, *tty;

main(argc, argv)
	int argc;
	char **argv;
{
	extern int optind;
	extern char *optarg, **environ;
	struct timeval tp;
	struct group *gr;
	register int ch;
	register char *p;
	int ask, fflag, hflag, pflag, cnt, uid;
	int quietlog, rval;
	char *domain, *salt, *ttyn;
	char tbuf[MAXPATHLEN + 2], tname[sizeof(_PATH_TTY) + 10];
	char localhost[MAXHOSTNAMELEN];
	char *ctime(), *ttyname(), *stypeof(), *crypt(), *getpass();
	time_t time();
	off_t lseek();
	void timedout();

	(void)signal(SIGALRM, timedout);
	(void)alarm((u_int)timeout);
	(void)signal(SIGQUIT, SIG_IGN);
	(void)signal(SIGINT, SIG_IGN);
	(void)setpriority(PRIO_PROCESS, 0, 0);

	openlog("login", LOG_ODELAY, LOG_AUTH);

	/*
	 * -p is used by getty to tell login not to destroy the environment
 	 * -f is used to skip a second login authentication
	 * -h is used by other servers to pass the name of the remote
	 *    host to login so that it may be placed in utmp and wtmp
	 */
	domain = NULL;
	if (gethostname(localhost, sizeof(localhost)) < 0)
		syslog(LOG_ERR, "couldn't get local hostname: %m");
	else
		domain = index(localhost, '.');

	fflag = hflag = pflag = 0;
	uid = getuid();
	while ((ch = getopt(argc, argv, "fh:p")) != EOF)
		switch (ch) {
		case 'f':
			fflag = 1;
			break;
		case 'h':
			if (uid) {
				(void)fprintf(stderr,
				    "login: -h option: %s\n", strerror(EPERM));
				exit(1);
			}
			hflag = 1;
			if (domain && (p = index(optarg, '.')) &&
			    strcasecmp(p, domain) == 0)
				*p = 0;
			hostname = optarg;
			break;
		case 'p':
			pflag = 1;
			break;
		case '?':
		default:
			if (!uid)
				syslog(LOG_ERR, "invalid flag %c", ch);
			(void)fprintf(stderr,
			    "usage: login [-fp] [-h hostname] [username]\n");
			exit(1);
		}
	argc -= optind;
	argv += optind;
	if (*argv) {
		username = *argv;
		ask = 0;
	} else
		ask = 1;

	for (cnt = getdtablesize(); cnt > 2; cnt--)
		close(cnt);

	ttyn = ttyname(0);
	if (ttyn == NULL || *ttyn == '\0') {
		(void)sprintf(tname, "%s??", _PATH_TTY);
		ttyn = tname;
	}
	if (tty = rindex(ttyn, '/'))
		++tty;
	else
		tty = ttyn;

	for (cnt = 0;; ask = 1) {
		if (ask) {
			fflag = 0;
			getloginname();
		}
#ifdef	KERBEROS
		if ((instance = index(username, '.')) != NULL) {
			if (strncmp(instance, ".root", 5) == 0)
				rootlogin++;
			*instance++ = '\0';
		} else {
			rootlogin = 0;
			instance = "";
		}
#else
		rootlogin = 0;
#endif
		if (strlen(username) > UT_NAMESIZE)
			username[UT_NAMESIZE] = '\0';

		/*
		 * Note if trying multiple user names; log failures for
		 * previous user name, but don't bother logging one failure
		 * for nonexistent name (mistyped username).
		 */
		if (failures && strcmp(tbuf, username)) {
			if (failures > (pwd ? 0 : 1))
				badlogin(tbuf);
			failures = 0;
		}
		(void)strcpy(tbuf, username);

		if (pwd = getpwnam(username))
			salt = pwd->pw_passwd;
		else
			salt = "xx";

		/*
		 * if we have a valid account name, and it doesn't have a
		 * password, or the -f option was specified and the caller
		 * is root or the caller isn't changing their uid, don't
		 * authenticate.
		 */
		if (pwd && (*pwd->pw_passwd == '\0' ||
		    fflag && (uid == 0 || uid == pwd->pw_uid)))
			break;
		fflag = 0;
		if (pwd && pwd->pw_uid == 0)
			rootlogin = 1;

		(void)setpriority(PRIO_PROCESS, 0, -4);

		p = getpass("Password:");

		if (pwd) {
#ifdef KERBEROS
			rval = klogin(pwd, instance, localhost, p);
			if (rval == 0)
				authok = 1;
			else if (rval == 1) {
				if (pwd->pw_uid != 0)
					rootlogin = 0;
				rval = strcmp(crypt(p, salt), pwd->pw_passwd);
			}
#else
			if (pwd->pw_uid != 0)
				rootlogin = 0;
#ifdef DES
			rval = strcmp(crypt(p, salt), pwd->pw_passwd);
#else
			rval = strcmp(p, pwd->pw_passwd);
#endif
#endif
		}
		bzero(p, strlen(p));

		(void)setpriority(PRIO_PROCESS, 0, 0);

		/*
		 * If trying to log in as root without Kerberos,
		 * but with insecure terminal, refuse the login attempt.
		 */
#ifdef KERBEROS
		if (authok == 0)
#endif
		if (pwd && rootlogin && !rootterm(tty)) {
			(void)fprintf(stderr,
			    "%s login refused on this terminal.\n",
			    pwd->pw_name);
			if (hostname)
				syslog(LOG_NOTICE,
				    "LOGIN %s REFUSED FROM %s ON TTY %s",
				    pwd->pw_name, hostname, tty);
			else
				syslog(LOG_NOTICE,
				    "LOGIN %s REFUSED ON TTY %s",
				     pwd->pw_name, tty);
			continue;
		}

		if (pwd && !rval)
			break;

		(void)printf("Login incorrect\n");
		failures++;
		/* we allow 10 tries, but after 3 we start backing off */
		if (++cnt > 3) {
			if (cnt >= 10) {
				badlogin(username);
				sleepexit(1);
			}
			sleep((u_int)((cnt - 3) * 5));
		}
	}

	/* committed to login -- turn off timeout */
	(void)alarm((u_int)0);

	endpwent();

	/* if user not super-user, check for disabled logins */
	if (!rootlogin)
		checknologin();

	if (chdir(pwd->pw_dir) < 0) {
		(void)printf("No home directory %s!\n", pwd->pw_dir);
		if (chdir("/"))
			exit(0);
		pwd->pw_dir = "/";
		(void)printf("Logging in with home = \"/\".\n");
	}

	quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;

	if (pwd->pw_change || pwd->pw_expire)
		(void)gettimeofday(&tp, (struct timezone *)NULL);
	if (pwd->pw_change)
		if (tp.tv_sec >= pwd->pw_change) {
			(void)printf("Sorry -- your password has expired.\n");
			sleepexit(1);
		} else if (pwd->pw_change - tp.tv_sec <
		    2 * DAYSPERWEEK * SECSPERDAY && !quietlog)
			(void)printf("Warning: your password expires on %s",
			    ctime(&pwd->pw_expire));
	if (pwd->pw_expire)
		if (tp.tv_sec >= pwd->pw_expire) {
			(void)printf("Sorry -- your account has expired.\n");
			sleepexit(1);
		} else if (pwd->pw_expire - tp.tv_sec <
		    2 * DAYSPERWEEK * SECSPERDAY && !quietlog)
			(void)printf("Warning: your account expires on %s",
			    ctime(&pwd->pw_expire));

	/* nothing else left to fail -- really log in */
	{
		struct utmp utmp;

		bzero((void *)&utmp, sizeof(utmp));
		(void)time(&utmp.ut_time);
		strncpy(utmp.ut_name, username, sizeof(utmp.ut_name));
		if (hostname)
			strncpy(utmp.ut_host, hostname, sizeof(utmp.ut_host));
		strncpy(utmp.ut_line, tty, sizeof(utmp.ut_line));
		login(&utmp);
	}

	dolastlog(quietlog);

	(void)chown(ttyn, pwd->pw_uid,
	    (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid);
	(void)setgid(pwd->pw_gid);

	initgroups(username, pwd->pw_gid);

	if (*pwd->pw_shell == '\0')
		pwd->pw_shell = _PATH_BSHELL;

	/* destroy environment unless user has requested preservation */
	if (!pflag)
		environ = envinit;
	(void)setenv("HOME", pwd->pw_dir, 1);
	(void)setenv("SHELL", pwd->pw_shell, 1);
	if (term[0] == '\0')
		strncpy(term, stypeof(tty), sizeof(term));
	(void)setenv("TERM", term, 0);
	(void)setenv("LOGNAME", pwd->pw_name, 1);
	(void)setenv("USER", pwd->pw_name, 1);
	(void)setenv("PATH", _PATH_DEFPATH, 0);
#ifdef KERBEROS
	if (krbtkfile_env)
		(void)setenv("KRBTKFILE", krbtkfile_env, 1);
#endif

	if (tty[sizeof("tty")-1] == 'd')
		syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name);
	/* if fflag is on, assume caller/authenticator has logged root login */
	if (rootlogin && fflag == 0)
		if (hostname)
			syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s",
			    username, tty, hostname);
		else
			syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s", username, tty);

#ifdef KERBEROS
	if (!quietlog && notickets == 1)
		(void)printf("Warning: no Kerberos tickets issued.\n");
#endif

	if (!quietlog) {
		struct stat st;

		printf("%s%s",
			"386BSD Release 0.1 by William and Lynne Jolitz.\n",
"Copyright (c) 1989,1990,1991,1992 William F. Jolitz. All rights reserved.\n\
Based in part on work by the 386BSD User Community and the\n\
BSD Networking Software, Release 2 by UCB EECS Department.\n");

		motd();
		(void)sprintf(tbuf, "%s/%s", _PATH_MAILDIR, pwd->pw_name);
		if (stat(tbuf, &st) == 0 && st.st_size != 0)
			(void)printf("You have %smail.\n",
			    (st.st_mtime > st.st_atime) ? "new " : "");
	}

	(void)signal(SIGALRM, SIG_DFL);
	(void)signal(SIGQUIT, SIG_DFL);
	(void)signal(SIGINT, SIG_DFL);
	(void)signal(SIGTSTP, SIG_IGN);

	tbuf[0] = '-';
	strcpy(tbuf + 1, (p = rindex(pwd->pw_shell, '/')) ?
	    p + 1 : pwd->pw_shell);

	if (setlogin(pwd->pw_name) < 0)
		syslog(LOG_ERR, "setlogin() failure: %m");

	/* discard permissions last so can't get killed and drop core */
	if (rootlogin)
		(void) setuid(0);
	else
		(void) setuid(pwd->pw_uid);

	execlp(pwd->pw_shell, tbuf, 0);
	(void)fprintf(stderr, "%s: %s\n", pwd->pw_shell, strerror(errno));
	exit(1);
}

#ifdef	KERBEROS
#define	NBUFSIZ		(UT_NAMESIZE + 1 + 5) /* .root suffix */
#else
#define	NBUFSIZ		(UT_NAMESIZE + 1)
#endif

getloginname()
{
	register int ch;
	register char *p;
	static char nbuf[NBUFSIZ];

	for (;;) {
		(void)printf("login: ");
		for (p = nbuf; (ch = getchar()) != '\n'; ) {
			if (ch == EOF) {
				badlogin(username);
				exit(0);
			}
			if (p < nbuf + (NBUFSIZ - 1))
				*p++ = ch;
		}
		if (p > nbuf)
			if (nbuf[0] == '-')
				(void)fprintf(stderr,
				    "login names may not start with '-'.\n");
			else {
				*p = '\0';
				username = nbuf;
				break;
			}
	}
}

void
timedout()
{
	(void)fprintf(stderr, "Login timed out after %d seconds\n", timeout);
	exit(0);
}

rootterm(ttyn)
	char *ttyn;
{
	struct ttyent *t;

	return((t = getttynam(ttyn)) && t->ty_status&TTY_SECURE);
}

jmp_buf motdinterrupt;

motd()
{
	register int fd, nchars;
	sig_t oldint;
	void sigint();
	char tbuf[8192];

	if ((fd = open(_PATH_MOTDFILE, O_RDONLY, 0)) < 0)
		return;
	oldint = signal(SIGINT, sigint);
	if (setjmp(motdinterrupt) == 0)
		while ((nchars = read(fd, tbuf, sizeof(tbuf))) > 0)
			(void)write(fileno(stdout), tbuf, nchars);
	(void)signal(SIGINT, oldint);
	(void)close(fd);
}

void
sigint()
{
	longjmp(motdinterrupt, 1);
}

checknologin()
{
	register int fd, nchars;
	char tbuf[8192];

	if ((fd = open(_PATH_NOLOGIN, O_RDONLY, 0)) >= 0) {
		while ((nchars = read(fd, tbuf, sizeof(tbuf))) > 0)
			(void)write(fileno(stdout), tbuf, nchars);
		sleepexit(0);
	}
}

dolastlog(quiet)
	int quiet;
{
	struct lastlog ll;
	int fd;
	char *ctime();

	if ((fd = open(_PATH_LASTLOG, O_RDWR, 0)) >= 0) {
		(void)lseek(fd, (off_t)pwd->pw_uid * sizeof(ll), L_SET);
		if (!quiet) {
			if (read(fd, (char *)&ll, sizeof(ll)) == sizeof(ll) &&
			    ll.ll_time != 0) {
				(void)printf("Last login: %.*s ",
				    24-5, (char *)ctime(&ll.ll_time));
				if (*ll.ll_host != '\0')
					(void)printf("from %.*s\n",
					    sizeof(ll.ll_host), ll.ll_host);
				else
					(void)printf("on %.*s\n",
					    sizeof(ll.ll_line), ll.ll_line);
			}
			(void)lseek(fd, (off_t)pwd->pw_uid * sizeof(ll), L_SET);
		}
		bzero((void *)&ll, sizeof(ll));
		(void)time(&ll.ll_time);
		strncpy(ll.ll_line, tty, sizeof(ll.ll_line));
		if (hostname)
			strncpy(ll.ll_host, hostname, sizeof(ll.ll_host));
		(void)write(fd, (char *)&ll, sizeof(ll));
		(void)close(fd);
	}
}

badlogin(name)
	char *name;
{
	if (failures == 0)
		return;
	if (hostname) {
		syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s",
		    failures, failures > 1 ? "S" : "", hostname);
		syslog(LOG_AUTHPRIV|LOG_NOTICE,
		    "%d LOGIN FAILURE%s FROM %s, %s",
		    failures, failures > 1 ? "S" : "", hostname, name);
	} else {
		syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s",
		    failures, failures > 1 ? "S" : "", tty);
		syslog(LOG_AUTHPRIV|LOG_NOTICE,
		    "%d LOGIN FAILURE%s ON %s, %s",
		    failures, failures > 1 ? "S" : "", tty, name);
	}
}

#undef	UNKNOWN
#define	UNKNOWN	"su"

char *
stypeof(ttyid)
	char *ttyid;
{
	struct ttyent *t;

	return(ttyid && (t = getttynam(ttyid)) ? t->ty_type : UNKNOWN);
}

sleepexit(eval)
	int eval;
{
	sleep((u_int)5);
	exit(eval);
}