2 * Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 * Copyright (c) 2002 Networks Associates Technologies, Inc.
7 * Portions of this software were developed for the FreeBSD Project by
8 * ThinkSec AS and NAI Labs, the Security Research Division of Network
9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
10 * ("CBOSS"), as part of the DARPA CHATS research program.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94";
47 #include <sys/cdefs.h>
48 __FBSDID("$FreeBSD$");
52 * login -h hostname (for telnetd, etc.)
53 * login -f name (for pre-authenticated login: datakit, xterm, etc.)
56 #include <sys/copyright.h>
57 #include <sys/param.h>
61 #include <sys/resource.h>
68 #include <login_cap.h>
79 #include <security/pam_appl.h>
80 #include <security/openpam.h>
83 #include "pathnames.h"
85 static int auth_pam(void);
86 static void bail(int, int);
87 static int export(const char *);
88 static void export_pam_environment(void);
89 static int motd(const char *);
90 static void badlogin(char *);
91 static char *getloginname(void);
92 static void pam_syslog(const char *);
93 static void pam_cleanup(void);
94 static void refused(const char *, const char *, int);
95 static const char *stypeof(char *);
96 static void sigint(int);
97 static void timedout(int);
98 static void usage(void);
100 #define TTYGRPNAME "tty" /* group to own ttys */
101 #define DEFAULT_BACKOFF 3
102 #define DEFAULT_RETRIES 10
103 #define DEFAULT_PROMPT "login: "
104 #define DEFAULT_PASSWD_PROMPT "Password:"
105 #define TERM_UNKNOWN "su"
106 #define DEFAULT_WARN (2L * 7L * 86400L) /* Two weeks */
107 #define NO_SLEEP_EXIT 0
111 * This bounds the time given to login. Not a define so it can
112 * be patched on machines where it's too small.
114 static u_int timeout = 300;
116 /* Buffer for signal handling of timeout */
117 static jmp_buf timeout_buf;
122 static char *envinit[1]; /* empty environment list */
125 * Command line flags and arguments
127 static int fflag; /* -f: do not perform authentication */
128 static int hflag; /* -h: login from remote host */
129 static char *hostname; /* hostname from command line */
130 static int pflag; /* -p: preserve environment */
135 static char *username; /* user name */
136 static char *olduser; /* previous user name */
141 static char default_prompt[] = DEFAULT_PROMPT;
142 static const char *prompt;
143 static char default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT;
144 static const char *passwd_prompt;
151 static pam_handle_t *pamh = NULL;
152 static struct pam_conv pamc = { openpam_ttyconv, NULL };
154 static int pam_silent = PAM_SILENT;
155 static int pam_cred_established;
156 static int pam_session_established;
159 main(int argc, char *argv[])
163 int retries, backoff;
164 int ask, ch, cnt, quietlog, rootlogin, rval;
169 char tname[sizeof(_PATH_TTY) + 10];
172 const char *shell = NULL;
173 login_cap_t *lc = NULL;
174 login_cap_t *lc_user = NULL;
177 (void)signal(SIGQUIT, SIG_IGN);
178 (void)signal(SIGINT, SIG_IGN);
179 (void)signal(SIGHUP, SIG_IGN);
180 if (setjmp(timeout_buf)) {
183 (void)fprintf(stderr, "Login timed out after %d seconds\n",
185 bail(NO_SLEEP_EXIT, 0);
187 (void)signal(SIGALRM, timedout);
188 (void)alarm(timeout);
189 (void)setpriority(PRIO_PROCESS, 0, 0);
191 openlog("login", LOG_ODELAY, LOG_AUTH);
197 while ((ch = getopt(argc, argv, "fh:p")) != -1)
204 errx(1, "-h option: %s", strerror(EPERM));
205 if (strlen(optarg) >= MAXHOSTNAMELEN)
206 errx(1, "-h option: %s: exceeds maximum "
207 "hostname size", optarg);
217 syslog(LOG_ERR, "invalid flag %c", ch);
224 username = strdup(*argv);
225 if (username == NULL)
232 setproctitle("-%s", getprogname());
234 for (cnt = getdtablesize(); cnt > 2; cnt--)
240 ttyn = ttyname(STDIN_FILENO);
241 if (ttyn == NULL || *ttyn == '\0') {
242 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY);
245 if ((tty = strrchr(ttyn, '/')) != NULL)
251 * Get "login-retries" & "login-backoff" from default class
253 lc = login_getclass(NULL);
254 prompt = login_getcapstr(lc, "login_prompt",
255 default_prompt, default_prompt);
256 passwd_prompt = login_getcapstr(lc, "passwd_prompt",
257 default_passwd_prompt, default_passwd_prompt);
258 retries = login_getcapnum(lc, "login-retries",
259 DEFAULT_RETRIES, DEFAULT_RETRIES);
260 backoff = login_getcapnum(lc, "login-backoff",
261 DEFAULT_BACKOFF, DEFAULT_BACKOFF);
266 * Try to authenticate the user until we succeed or time out.
268 for (cnt = 0;; ask = 1) {
274 username = getloginname();
279 * Note if trying multiple user names; log failures for
280 * previous user name, but don't bother logging one failure
281 * for nonexistent name (mistyped username).
283 if (failures && strcmp(olduser, username) != 0) {
284 if (failures > (pwd ? 0 : 1))
289 * Load the PAM policy and set some variables
291 pam_err = pam_start("login", username, &pamc, &pamh);
292 if (pam_err != PAM_SUCCESS) {
293 pam_syslog("pam_start()");
294 bail(NO_SLEEP_EXIT, 1);
296 pam_err = pam_set_item(pamh, PAM_TTY, tty);
297 if (pam_err != PAM_SUCCESS) {
298 pam_syslog("pam_set_item(PAM_TTY)");
299 bail(NO_SLEEP_EXIT, 1);
301 pam_err = pam_set_item(pamh, PAM_RHOST, hostname);
302 if (pam_err != PAM_SUCCESS) {
303 pam_syslog("pam_set_item(PAM_RHOST)");
304 bail(NO_SLEEP_EXIT, 1);
307 pwd = getpwnam(username);
308 if (pwd != NULL && pwd->pw_uid == 0)
312 * If the -f option was specified and the caller is
313 * root or the caller isn't changing their uid, don't
316 if (pwd != NULL && fflag &&
317 (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) {
318 /* already authenticated */
322 (void)setpriority(PRIO_PROCESS, 0, -4);
324 (void)setpriority(PRIO_PROCESS, 0, 0);
327 if (pwd && rval == 0)
332 (void)printf("Login incorrect\n");
336 * Allow up to 'retry' (10) attempts, but start
337 * backing off after 'backoff' (3) attempts.
339 if (++cnt > backoff) {
340 if (cnt >= retries) {
344 sleep((u_int)((cnt - backoff) * 5));
348 /* committed to login -- turn off timeout */
349 (void)alarm((u_int)0);
350 (void)signal(SIGHUP, SIG_DFL);
355 * Establish the login class.
357 lc = login_getpwclass(pwd);
358 lc_user = login_getuserclass(pwd);
360 if (!(quietlog = login_getcapbool(lc_user, "hushlogin", 0)))
361 quietlog = login_getcapbool(lc, "hushlogin", 0);
364 * Switching needed for NFS with root access disabled.
366 * XXX: This change fails to modify the additional groups for the
367 * process, and as such, may restrict rights normally granted
368 * through those groups.
370 (void)setegid(pwd->pw_gid);
371 (void)seteuid(rootlogin ? 0 : pwd->pw_uid);
372 if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) {
373 if (login_getcapbool(lc, "requirehome", 0))
374 refused("Home directory not available", "HOMEDIR", 1);
376 refused("Cannot find root directory", "ROOTDIR", 1);
377 if (!quietlog || *pwd->pw_dir)
378 printf("No home directory.\nLogging in with home = \"/\".\n");
379 pwd->pw_dir = strdup("/");
380 if (pwd->pw_dir == NULL) {
381 syslog(LOG_NOTICE, "strdup(): %m");
388 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;
393 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell);
394 if (*pwd->pw_shell == '\0')
395 pwd->pw_shell = strdup(_PATH_BSHELL);
396 if (pwd->pw_shell == NULL) {
397 syslog(LOG_NOTICE, "strdup(): %m");
400 if (*shell == '\0') /* Not overridden */
401 shell = pwd->pw_shell;
402 if ((shell = strdup(shell)) == NULL) {
403 syslog(LOG_NOTICE, "strdup(): %m");
408 * Set device protections, depending on what terminal the
409 * user is logged in. This feature is used on Suns to give
410 * console users better privacy.
412 login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);
415 * Clear flags of the tty. None should be set, and when the
416 * user sets them otherwise, this can cause the chown to fail.
417 * Since it isn't clear that flags are useful on character
418 * devices, we just clear them.
420 * We don't log in the case of EOPNOTSUPP because dev might be
421 * on NFS, which doesn't support chflags.
423 * We don't log in the EROFS because that means that /dev is on
424 * a read only file system and we assume that the permissions there
427 if (ttyn != tname && chflags(ttyn, 0))
428 if (errno != EOPNOTSUPP && errno != EROFS)
429 syslog(LOG_ERR, "chflags(%s): %m", ttyn);
430 if (ttyn != tname && chown(ttyn, pwd->pw_uid,
431 (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid))
433 syslog(LOG_ERR, "chown(%s): %m", ttyn);
436 * Exclude cons/vt/ptys only, assume dialup otherwise
437 * TODO: Make dialup tty determination a library call
438 * for consistency (finger etc.)
440 if (hflag && isdialuptty(tty))
441 syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name);
445 * Syslog each successful login, so we don't have to watch
446 * hundreds of wtmp or lastlogin files.
449 syslog(LOG_INFO, "login from %s on %s as %s",
450 hostname, tty, pwd->pw_name);
452 syslog(LOG_INFO, "login on %s as %s",
457 * If fflag is on, assume caller/authenticator has logged root
460 if (rootlogin && fflag == 0) {
462 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s",
463 username, tty, hostname);
465 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s",
470 * Destroy environment unless user has requested its
471 * preservation - but preserve TERM in all cases
473 term = getenv("TERM");
477 setenv("TERM", term, 0);
480 * PAM modules might add supplementary groups during pam_setcred().
482 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) {
483 syslog(LOG_ERR, "setusercontext() failed - exiting");
484 bail(NO_SLEEP_EXIT, 1);
487 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED);
488 if (pam_err != PAM_SUCCESS) {
489 pam_syslog("pam_setcred()");
490 bail(NO_SLEEP_EXIT, 1);
492 pam_cred_established = 1;
494 pam_err = pam_open_session(pamh, pam_silent);
495 if (pam_err != PAM_SUCCESS) {
496 pam_syslog("pam_open_session()");
497 bail(NO_SLEEP_EXIT, 1);
499 pam_session_established = 1;
502 * We must fork() before setuid() because we need to call
503 * pam_close_session() as root.
508 } else if (pid != 0) {
510 * Parent: wait for child to finish, then clean up
514 setproctitle("-%s [pam]", getprogname());
515 waitpid(pid, &status, 0);
516 bail(NO_SLEEP_EXIT, 0);
520 * NOTICE: We are now in the child process!
524 * Add any environment variables the PAM modules may have set.
526 export_pam_environment();
529 * We're done with PAM now; our parent will deal with the rest.
535 * We don't need to be root anymore, so set the login name and
538 if (setlogin(username) != 0) {
539 syslog(LOG_ERR, "setlogin(%s): %m - exiting", username);
540 bail(NO_SLEEP_EXIT, 1);
542 if (setusercontext(lc, pwd, pwd->pw_uid,
543 LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) {
544 syslog(LOG_ERR, "setusercontext() failed - exiting");
548 (void)setenv("SHELL", pwd->pw_shell, 1);
549 (void)setenv("HOME", pwd->pw_dir, 1);
550 /* Overwrite "term" from login.conf(5) for any known TERM */
551 if (term == NULL && (tp = stypeof(tty)) != NULL)
552 (void)setenv("TERM", tp, 1);
554 (void)setenv("TERM", TERM_UNKNOWN, 0);
555 (void)setenv("LOGNAME", username, 1);
556 (void)setenv("USER", username, 1);
557 (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0);
562 cw = login_getcapstr(lc, "copyright", NULL, NULL);
563 if (cw == NULL || motd(cw) == -1)
564 (void)printf("%s", copyright);
568 cw = login_getcapstr(lc, "welcome", NULL, NULL);
569 if (cw != NULL && access(cw, F_OK) == 0)
572 motd(_PATH_MOTDFILE);
574 if (login_getcapbool(lc_user, "nocheckmail", 0) == 0 &&
575 login_getcapbool(lc, "nocheckmail", 0) == 0) {
578 /* $MAIL may have been set by class. */
581 asprintf(&cx, "%s/%s",
582 _PATH_MAILDIR, pwd->pw_name);
584 if (cx && stat(cx, &st) == 0 && st.st_size != 0)
585 (void)printf("You have %smail.\n",
586 (st.st_mtime > st.st_atime) ? "new " : "");
587 if (getenv("MAIL") == NULL)
592 login_close(lc_user);
595 (void)signal(SIGALRM, SIG_DFL);
596 (void)signal(SIGQUIT, SIG_DFL);
597 (void)signal(SIGINT, SIG_DFL);
598 (void)signal(SIGTSTP, SIG_IGN);
601 * Login shells have a leading '-' in front of argv[0]
603 p = strrchr(pwd->pw_shell, '/');
604 if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) {
605 syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size",
607 errx(1, "shell exceeds maximum pathname size");
608 } else if (arg0 == NULL) {
609 err(1, "asprintf()");
612 execlp(shell, arg0, (char *)0);
621 * Attempt to authenticate the user using PAM. Returns 0 if the user is
622 * authenticated, or 1 if not authenticated. If some sort of PAM system
623 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this
624 * function returns -1. This can be used as an indication that we should
625 * fall back to a different authentication mechanism.
630 const char *tmpl_user;
634 pam_err = pam_authenticate(pamh, pam_silent);
639 * With PAM we support the concept of a "template"
640 * user. The user enters a login name which is
641 * authenticated by PAM, usually via a remote service
642 * such as RADIUS or TACACS+. If authentication
643 * succeeds, a different but related "template" name
644 * is used for setting the credentials, shell, and
645 * home directory. The name the user enters need only
646 * exist on the remote authentication server, but the
647 * template name must be present in the local password
650 * This is supported by two various mechanisms in the
651 * individual modules. However, from the application's
652 * point of view, the template user is always passed
653 * back as a changed value of the PAM_USER item.
655 pam_err = pam_get_item(pamh, PAM_USER, &item);
656 if (pam_err == PAM_SUCCESS) {
657 tmpl_user = (const char *)item;
658 if (strcmp(username, tmpl_user) != 0)
659 pwd = getpwnam(tmpl_user);
661 pam_syslog("pam_get_item(PAM_USER)");
667 case PAM_USER_UNKNOWN:
673 pam_syslog("pam_authenticate()");
679 pam_err = pam_acct_mgmt(pamh, pam_silent);
683 case PAM_NEW_AUTHTOK_REQD:
684 pam_err = pam_chauthtok(pamh,
685 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK);
686 if (pam_err != PAM_SUCCESS) {
687 pam_syslog("pam_chauthtok()");
692 pam_syslog("pam_acct_mgmt()");
699 pam_end(pamh, pam_err);
706 * Export any environment variables PAM modules may have set
709 export_pam_environment()
714 pam_env = pam_getenvlist(pamh);
715 if (pam_env != NULL) {
716 for (pp = pam_env; *pp != NULL; pp++) {
724 * Perform sanity checks on an environment variable:
725 * - Make sure there is an '=' in the string.
726 * - Make sure the string doesn't run on too long.
727 * - Do not export certain variables. This list was taken from the
728 * Solaris pam_putenv(3) man page.
732 export(const char *s)
734 static const char *noexport[] = {
735 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
741 if (strlen(s) > 1024 || strchr(s, '=') == NULL)
743 if (strncmp(s, "LD_", 3) == 0)
745 for (pp = noexport; *pp != NULL; pp++) {
747 if (s[n] == '=' && strncmp(s, *pp, n) == 0)
758 (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n");
763 * Prompt user and read login name from stdin.
771 nbuf = malloc(MAXLOGNAME);
775 (void)printf("%s", prompt);
776 for (p = nbuf; (ch = getchar()) != '\n'; ) {
779 bail(NO_SLEEP_EXIT, 0);
781 if (p < nbuf + MAXLOGNAME - 1)
787 if (nbuf[0] == '-') {
789 memmove(nbuf, nbuf + 1, strlen(nbuf));
791 pam_silent = PAM_SILENT;
797 * SIGINT handler for motd().
799 static volatile int motdinterrupt;
801 sigint(int signo __unused)
807 * Display the contents of a file (such as /etc/motd).
810 motd(const char *motdfile)
816 if ((f = fopen(motdfile, "r")) == NULL)
819 oldint = signal(SIGINT, sigint);
820 while ((ch = fgetc(f)) != EOF && !motdinterrupt)
822 signal(SIGINT, oldint);
823 if (ch != EOF || ferror(f)) {
832 * SIGALRM handler, to enforce login prompt timeout.
834 * XXX This can potentially confuse the hell out of PAM. We should
835 * XXX instead implement a conversation function that returns
836 * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal
837 * XXX handler just set a flag.
840 timedout(int signo __unused)
843 longjmp(timeout_buf, signo);
853 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s",
854 failures, failures > 1 ? "S" : "", hostname);
855 syslog(LOG_AUTHPRIV|LOG_NOTICE,
856 "%d LOGIN FAILURE%s FROM %s, %s",
857 failures, failures > 1 ? "S" : "", hostname, name);
859 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s",
860 failures, failures > 1 ? "S" : "", tty);
861 syslog(LOG_AUTHPRIV|LOG_NOTICE,
862 "%d LOGIN FAILURE%s ON %s, %s",
863 failures, failures > 1 ? "S" : "", tty, name);
873 if (ttyid != NULL && *ttyid != '\0') {
874 t = getttynam(ttyid);
875 if (t != NULL && t->ty_type != NULL)
882 refused(const char *msg, const char *rtype, int lout)
886 printf("%s.\n", msg);
888 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s",
889 pwd->pw_name, rtype, hostname, tty);
891 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s",
892 pwd->pw_name, rtype, tty);
901 pam_syslog(const char *msg)
903 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err));
914 if (pam_session_established) {
915 pam_err = pam_close_session(pamh, 0);
916 if (pam_err != PAM_SUCCESS)
917 pam_syslog("pam_close_session()");
919 pam_session_established = 0;
920 if (pam_cred_established) {
921 pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED);
922 if (pam_err != PAM_SUCCESS)
923 pam_syslog("pam_setcred()");
925 pam_cred_established = 0;
926 pam_end(pamh, pam_err);
932 * Exit, optionally after sleeping a few seconds
935 bail(int sec, int eval)