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
77 static int auth_pam(void);
78 static void bail(int, int);
79 static void bail_internal(int, int, int);
80 static int export(const char *);
81 static void export_pam_environment(void);
82 static int motd(const char *);
83 static void badlogin(char *);
84 static char *getloginname(void);
85 static void pam_syslog(const char *);
86 static void pam_cleanup(void);
87 static void refused(const char *, const char *, int);
88 static const char *stypeof(char *);
89 static void sigint(int);
90 static void timedout(int);
91 static void bail_sig(int);
92 static 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 */
108 static u_int timeout = 300;
109
110 /* Buffer for signal handling of timeout */
111 static jmp_buf timeout_buf;
112
113 char pwbuf[1024];
114 struct passwd pwres;
115 struct passwd *pwd;
116 static int failures;
117
118 static char *envinit[1]; /* empty environment list */
119
120 /*
121 * Command line flags and arguments
122 */
123 static int fflag; /* -f: do not perform authentication */
124 static int hflag; /* -h: login from remote host */
125 static char *hostname; /* hostname from command line */
126 static int pflag; /* -p: preserve environment */
127
128 /*
129 * User name
130 */
131 static char *username; /* user name */
132 static char *olduser; /* previous user name */
133
134 /*
135 * Prompts
136 */
137 static char default_prompt[] = DEFAULT_PROMPT;
138 static const char *prompt;
139 static char default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT;
140 static const char *passwd_prompt;
141
142 static char *tty;
143
144 /*
145 * PAM data
146 */
147 static pam_handle_t *pamh = NULL;
148 static struct pam_conv pamc = { openpam_ttyconv, NULL };
149 static int pam_err;
150 static int pam_silent = PAM_SILENT;
151 static int pam_cred_established;
152 static int pam_session_established;
153
154 int
main(int argc,char * argv[])155 main(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 */
676 static int
auth_pam(void)677 auth_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 */
759 static void
export_pam_environment(void)760 export_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 */
782 static int
export(const char * s)783 export(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
811 static void
usage(void)812 usage(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 */
822 static char *
getloginname(void)823 getloginname(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 */
856 static volatile int motdinterrupt;
857 static void
sigint(int signo __unused)858 sigint(int signo __unused)
859 {
860 motdinterrupt = 1;
861 }
862
863 /*
864 * Display the contents of a file (such as /etc/motd).
865 */
866 static int
motd(const char * motdfile)867 motd(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 */
899 static void
timedout(int signo __unused)900 timedout(int signo __unused)
901 {
902
903 longjmp(timeout_buf, signo);
904 }
905
906 static void
badlogin(char * name)907 badlogin(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
928 const char *
stypeof(char * ttyid)929 stypeof(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
941 static void
refused(const char * msg,const char * rtype,int lout)942 refused(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 */
960 static void
pam_syslog(const char * msg)961 pam_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 */
969 static void
pam_cleanup(void)970 pam_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
991 static void
bail_internal(int sec,int eval,int signo)992 bail_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 */
1019 static void
bail(int sec,int eval)1020 bail(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 */
1030 static void
bail_sig(int signo)1031 bail_sig(int signo)
1032 {
1033 bail_internal(NO_SLEEP_EXIT, 0, signo);
1034 }
1035