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 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 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 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 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 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 * 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 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 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 900 timedout(int signo __unused) 901 { 902 903 longjmp(timeout_buf, signo); 904 } 905 906 static void 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 * 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 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 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 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 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 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 1031 bail_sig(int signo) 1032 { 1033 bail_internal(NO_SLEEP_EXIT, 0, signo); 1034 } 1035