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;
176 (void)signal(SIGQUIT, SIG_IGN);
177 (void)signal(SIGINT, SIG_IGN);
178 (void)signal(SIGHUP, SIG_IGN);
179 if (setjmp(timeout_buf)) {
182 (void)fprintf(stderr, "Login timed out after %d seconds\n",
184 bail(NO_SLEEP_EXIT, 0);
186 (void)signal(SIGALRM, timedout);
187 (void)alarm(timeout);
188 (void)setpriority(PRIO_PROCESS, 0, 0);
190 openlog("login", LOG_ODELAY, LOG_AUTH);
196 while ((ch = getopt(argc, argv, "fh:p")) != -1)
203 errx(1, "-h option: %s", strerror(EPERM));
204 if (strlen(optarg) >= MAXHOSTNAMELEN)
205 errx(1, "-h option: %s: exceeds maximum "
206 "hostname size", optarg);
216 syslog(LOG_ERR, "invalid flag %c", ch);
223 username = strdup(*argv);
224 if (username == NULL)
231 setproctitle("-%s", getprogname());
233 for (cnt = getdtablesize(); cnt > 2; cnt--)
239 ttyn = ttyname(STDIN_FILENO);
240 if (ttyn == NULL || *ttyn == '\0') {
241 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY);
244 if ((tty = strrchr(ttyn, '/')) != NULL)
250 * Get "login-retries" & "login-backoff" from default class
252 lc = login_getclass(NULL);
253 prompt = login_getcapstr(lc, "login_prompt",
254 default_prompt, default_prompt);
255 passwd_prompt = login_getcapstr(lc, "passwd_prompt",
256 default_passwd_prompt, default_passwd_prompt);
257 retries = login_getcapnum(lc, "login-retries",
258 DEFAULT_RETRIES, DEFAULT_RETRIES);
259 backoff = login_getcapnum(lc, "login-backoff",
260 DEFAULT_BACKOFF, DEFAULT_BACKOFF);
265 * Try to authenticate the user until we succeed or time out.
267 for (cnt = 0;; ask = 1) {
273 username = getloginname();
278 * Note if trying multiple user names; log failures for
279 * previous user name, but don't bother logging one failure
280 * for nonexistent name (mistyped username).
282 if (failures && strcmp(olduser, username) != 0) {
283 if (failures > (pwd ? 0 : 1))
288 * Load the PAM policy and set some variables
290 pam_err = pam_start("login", username, &pamc, &pamh);
291 if (pam_err != PAM_SUCCESS) {
292 pam_syslog("pam_start()");
293 bail(NO_SLEEP_EXIT, 1);
295 pam_err = pam_set_item(pamh, PAM_TTY, tty);
296 if (pam_err != PAM_SUCCESS) {
297 pam_syslog("pam_set_item(PAM_TTY)");
298 bail(NO_SLEEP_EXIT, 1);
300 pam_err = pam_set_item(pamh, PAM_RHOST, hostname);
301 if (pam_err != PAM_SUCCESS) {
302 pam_syslog("pam_set_item(PAM_RHOST)");
303 bail(NO_SLEEP_EXIT, 1);
306 pwd = getpwnam(username);
307 if (pwd != NULL && pwd->pw_uid == 0)
311 * If the -f option was specified and the caller is
312 * root or the caller isn't changing their uid, don't
315 if (pwd != NULL && fflag &&
316 (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) {
317 /* already authenticated */
321 (void)setpriority(PRIO_PROCESS, 0, -4);
323 (void)setpriority(PRIO_PROCESS, 0, 0);
326 if (pwd && rval == 0)
331 (void)printf("Login incorrect\n");
335 * Allow up to 'retry' (10) attempts, but start
336 * backing off after 'backoff' (3) attempts.
338 if (++cnt > backoff) {
339 if (cnt >= retries) {
343 sleep((u_int)((cnt - backoff) * 5));
347 /* committed to login -- turn off timeout */
348 (void)alarm((u_int)0);
349 (void)signal(SIGHUP, SIG_DFL);
354 * Establish the login class.
356 lc = login_getpwclass(pwd);
358 quietlog = login_getcapbool(lc, "hushlogin", 0);
361 * Switching needed for NFS with root access disabled.
363 * XXX: This change fails to modify the additional groups for the
364 * process, and as such, may restrict rights normally granted
365 * through those groups.
367 (void)setegid(pwd->pw_gid);
368 (void)seteuid(rootlogin ? 0 : pwd->pw_uid);
369 if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) {
370 if (login_getcapbool(lc, "requirehome", 0))
371 refused("Home directory not available", "HOMEDIR", 1);
373 refused("Cannot find root directory", "ROOTDIR", 1);
374 if (!quietlog || *pwd->pw_dir)
375 printf("No home directory.\nLogging in with home = \"/\".\n");
376 pwd->pw_dir = strdup("/");
377 if (pwd->pw_dir == NULL) {
378 syslog(LOG_NOTICE, "strdup(): %m");
385 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0;
390 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell);
391 if (*pwd->pw_shell == '\0')
392 pwd->pw_shell = strdup(_PATH_BSHELL);
393 if (pwd->pw_shell == NULL) {
394 syslog(LOG_NOTICE, "strdup(): %m");
397 if (*shell == '\0') /* Not overridden */
398 shell = pwd->pw_shell;
399 if ((shell = strdup(shell)) == NULL) {
400 syslog(LOG_NOTICE, "strdup(): %m");
405 * Set device protections, depending on what terminal the
406 * user is logged in. This feature is used on Suns to give
407 * console users better privacy.
409 login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);
412 * Clear flags of the tty. None should be set, and when the
413 * user sets them otherwise, this can cause the chown to fail.
414 * Since it isn't clear that flags are useful on character
415 * devices, we just clear them.
417 * We don't log in the case of EOPNOTSUPP because dev might be
418 * on NFS, which doesn't support chflags.
420 * We don't log in the EROFS because that means that /dev is on
421 * a read only file system and we assume that the permissions there
424 if (ttyn != tname && chflags(ttyn, 0))
425 if (errno != EOPNOTSUPP && errno != EROFS)
426 syslog(LOG_ERR, "chflags(%s): %m", ttyn);
427 if (ttyn != tname && chown(ttyn, pwd->pw_uid,
428 (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid))
430 syslog(LOG_ERR, "chown(%s): %m", ttyn);
433 * Exclude cons/vt/ptys only, assume dialup otherwise
434 * TODO: Make dialup tty determination a library call
435 * for consistency (finger etc.)
437 if (hflag && isdialuptty(tty))
438 syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name);
442 * Syslog each successful login, so we don't have to watch
443 * hundreds of wtmp or lastlogin files.
446 syslog(LOG_INFO, "login from %s on %s as %s",
447 hostname, tty, pwd->pw_name);
449 syslog(LOG_INFO, "login on %s as %s",
454 * If fflag is on, assume caller/authenticator has logged root
457 if (rootlogin && fflag == 0) {
459 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s",
460 username, tty, hostname);
462 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s",
467 * Destroy environment unless user has requested its
468 * preservation - but preserve TERM in all cases
470 term = getenv("TERM");
474 setenv("TERM", term, 0);
477 * PAM modules might add supplementary groups during pam_setcred().
479 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) {
480 syslog(LOG_ERR, "setusercontext() failed - exiting");
481 bail(NO_SLEEP_EXIT, 1);
484 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED);
485 if (pam_err != PAM_SUCCESS) {
486 pam_syslog("pam_setcred()");
487 bail(NO_SLEEP_EXIT, 1);
489 pam_cred_established = 1;
491 pam_err = pam_open_session(pamh, pam_silent);
492 if (pam_err != PAM_SUCCESS) {
493 pam_syslog("pam_open_session()");
494 bail(NO_SLEEP_EXIT, 1);
496 pam_session_established = 1;
499 * We must fork() before setuid() because we need to call
500 * pam_close_session() as root.
505 } else if (pid != 0) {
507 * Parent: wait for child to finish, then clean up
511 setproctitle("-%s [pam]", getprogname());
512 waitpid(pid, &status, 0);
513 bail(NO_SLEEP_EXIT, 0);
517 * NOTICE: We are now in the child process!
521 * Add any environment variables the PAM modules may have set.
523 export_pam_environment();
526 * We're done with PAM now; our parent will deal with the rest.
532 * We don't need to be root anymore, so set the login name and
535 if (setlogin(username) != 0) {
536 syslog(LOG_ERR, "setlogin(%s): %m - exiting", username);
537 bail(NO_SLEEP_EXIT, 1);
539 if (setusercontext(lc, pwd, pwd->pw_uid,
540 LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) {
541 syslog(LOG_ERR, "setusercontext() failed - exiting");
545 (void)setenv("SHELL", pwd->pw_shell, 1);
546 (void)setenv("HOME", pwd->pw_dir, 1);
547 /* Overwrite "term" from login.conf(5) for any known TERM */
548 if (term == NULL && (tp = stypeof(tty)) != NULL)
549 (void)setenv("TERM", tp, 1);
551 (void)setenv("TERM", TERM_UNKNOWN, 0);
552 (void)setenv("LOGNAME", username, 1);
553 (void)setenv("USER", username, 1);
554 (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0);
559 cw = login_getcapstr(lc, "copyright", NULL, NULL);
560 if (cw == NULL || motd(cw) == -1)
561 (void)printf("%s", copyright);
565 cw = login_getcapstr(lc, "welcome", NULL, NULL);
566 if (cw != NULL && access(cw, F_OK) == 0)
569 motd(_PATH_MOTDFILE);
571 if (login_getcapbool(lc, "nocheckmail", 0) == 0) {
574 /* $MAIL may have been set by class. */
577 asprintf(&cx, "%s/%s",
578 _PATH_MAILDIR, pwd->pw_name);
580 if (cx && stat(cx, &st) == 0 && st.st_size != 0)
581 (void)printf("You have %smail.\n",
582 (st.st_mtime > st.st_atime) ? "new " : "");
583 if (getenv("MAIL") == NULL)
590 (void)signal(SIGALRM, SIG_DFL);
591 (void)signal(SIGQUIT, SIG_DFL);
592 (void)signal(SIGINT, SIG_DFL);
593 (void)signal(SIGTSTP, SIG_IGN);
596 * Login shells have a leading '-' in front of argv[0]
598 p = strrchr(pwd->pw_shell, '/');
599 if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) {
600 syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size",
602 errx(1, "shell exceeds maximum pathname size");
603 } else if (arg0 == NULL) {
604 err(1, "asprintf()");
607 execlp(shell, arg0, (char *)0);
616 * Attempt to authenticate the user using PAM. Returns 0 if the user is
617 * authenticated, or 1 if not authenticated. If some sort of PAM system
618 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this
619 * function returns -1. This can be used as an indication that we should
620 * fall back to a different authentication mechanism.
625 const char *tmpl_user;
629 pam_err = pam_authenticate(pamh, pam_silent);
634 * With PAM we support the concept of a "template"
635 * user. The user enters a login name which is
636 * authenticated by PAM, usually via a remote service
637 * such as RADIUS or TACACS+. If authentication
638 * succeeds, a different but related "template" name
639 * is used for setting the credentials, shell, and
640 * home directory. The name the user enters need only
641 * exist on the remote authentication server, but the
642 * template name must be present in the local password
645 * This is supported by two various mechanisms in the
646 * individual modules. However, from the application's
647 * point of view, the template user is always passed
648 * back as a changed value of the PAM_USER item.
650 pam_err = pam_get_item(pamh, PAM_USER, &item);
651 if (pam_err == PAM_SUCCESS) {
652 tmpl_user = (const char *)item;
653 if (strcmp(username, tmpl_user) != 0)
654 pwd = getpwnam(tmpl_user);
656 pam_syslog("pam_get_item(PAM_USER)");
662 case PAM_USER_UNKNOWN:
668 pam_syslog("pam_authenticate()");
674 pam_err = pam_acct_mgmt(pamh, pam_silent);
678 case PAM_NEW_AUTHTOK_REQD:
679 pam_err = pam_chauthtok(pamh,
680 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK);
681 if (pam_err != PAM_SUCCESS) {
682 pam_syslog("pam_chauthtok()");
687 pam_syslog("pam_acct_mgmt()");
694 pam_end(pamh, pam_err);
701 * Export any environment variables PAM modules may have set
704 export_pam_environment()
709 pam_env = pam_getenvlist(pamh);
710 if (pam_env != NULL) {
711 for (pp = pam_env; *pp != NULL; pp++) {
719 * Perform sanity checks on an environment variable:
720 * - Make sure there is an '=' in the string.
721 * - Make sure the string doesn't run on too long.
722 * - Do not export certain variables. This list was taken from the
723 * Solaris pam_putenv(3) man page.
727 export(const char *s)
729 static const char *noexport[] = {
730 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
736 if (strlen(s) > 1024 || strchr(s, '=') == NULL)
738 if (strncmp(s, "LD_", 3) == 0)
740 for (pp = noexport; *pp != NULL; pp++) {
742 if (s[n] == '=' && strncmp(s, *pp, n) == 0)
753 (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n");
758 * Prompt user and read login name from stdin.
766 nbuf = malloc(MAXLOGNAME);
770 (void)printf("%s", prompt);
771 for (p = nbuf; (ch = getchar()) != '\n'; ) {
774 bail(NO_SLEEP_EXIT, 0);
776 if (p < nbuf + MAXLOGNAME - 1)
782 if (nbuf[0] == '-') {
784 memmove(nbuf, nbuf + 1, strlen(nbuf));
786 pam_silent = PAM_SILENT;
792 * SIGINT handler for motd().
794 static volatile int motdinterrupt;
796 sigint(int signo __unused)
802 * Display the contents of a file (such as /etc/motd).
805 motd(const char *motdfile)
811 if ((f = fopen(motdfile, "r")) == NULL)
814 oldint = signal(SIGINT, sigint);
815 while ((ch = fgetc(f)) != EOF && !motdinterrupt)
817 signal(SIGINT, oldint);
818 if (ch != EOF || ferror(f)) {
827 * SIGALRM handler, to enforce login prompt timeout.
829 * XXX This can potentially confuse the hell out of PAM. We should
830 * XXX instead implement a conversation function that returns
831 * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal
832 * XXX handler just set a flag.
835 timedout(int signo __unused)
838 longjmp(timeout_buf, signo);
848 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s",
849 failures, failures > 1 ? "S" : "", hostname);
850 syslog(LOG_AUTHPRIV|LOG_NOTICE,
851 "%d LOGIN FAILURE%s FROM %s, %s",
852 failures, failures > 1 ? "S" : "", hostname, name);
854 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s",
855 failures, failures > 1 ? "S" : "", tty);
856 syslog(LOG_AUTHPRIV|LOG_NOTICE,
857 "%d LOGIN FAILURE%s ON %s, %s",
858 failures, failures > 1 ? "S" : "", tty, name);
868 if (ttyid != NULL && *ttyid != '\0') {
869 t = getttynam(ttyid);
870 if (t != NULL && t->ty_type != NULL)
877 refused(const char *msg, const char *rtype, int lout)
881 printf("%s.\n", msg);
883 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s",
884 pwd->pw_name, rtype, hostname, tty);
886 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s",
887 pwd->pw_name, rtype, tty);
896 pam_syslog(const char *msg)
898 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err));
909 if (pam_session_established) {
910 pam_err = pam_close_session(pamh, 0);
911 if (pam_err != PAM_SUCCESS)
912 pam_syslog("pam_close_session()");
914 pam_session_established = 0;
915 if (pam_cred_established) {
916 pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED);
917 if (pam_err != PAM_SUCCESS)
918 pam_syslog("pam_setcred()");
920 pam_cred_established = 0;
921 pam_end(pamh, pam_err);
927 * Exit, optionally after sleeping a few seconds
930 bail(int sec, int eval)