1 /*- 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. 5 * All rights reserved. 6 * 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. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 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. 27 * 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 38 * SUCH DAMAGE. 39 */ 40 41 #if 0 42 #ifndef lint 43 static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94"; 44 #endif 45 #endif 46 47 #include <sys/cdefs.h> 48 __FBSDID("$FreeBSD$"); 49 50 /* 51 * login [ name ] 52 * login -h hostname (for telnetd, etc.) 53 * login -f name (for pre-authenticated login: datakit, xterm, etc.) 54 */ 55 56 #include <sys/param.h> 57 #include <sys/file.h> 58 #include <sys/stat.h> 59 #include <sys/time.h> 60 #include <sys/resource.h> 61 #include <sys/wait.h> 62 63 #include <err.h> 64 #include <errno.h> 65 #include <grp.h> 66 #include <libutil.h> 67 #include <login_cap.h> 68 #include <pwd.h> 69 #include <setjmp.h> 70 #include <signal.h> 71 #include <stdio.h> 72 #include <stdlib.h> 73 #include <string.h> 74 #include <syslog.h> 75 #include <ttyent.h> 76 #include <unistd.h> 77 78 #include <security/pam_appl.h> 79 #include <security/openpam.h> 80 81 #include "login.h" 82 #include "pathnames.h" 83 84 static int auth_pam(void); 85 static void bail(int, int); 86 static void bail_internal(int, 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 bail_sig(int); 99 static void usage(void); 100 101 #define TTYGRPNAME "tty" /* group to own ttys */ 102 #define DEFAULT_BACKOFF 3 103 #define DEFAULT_RETRIES 10 104 #define DEFAULT_PROMPT "login: " 105 #define DEFAULT_PASSWD_PROMPT "Password:" 106 #define TERM_UNKNOWN "su" 107 #define DEFAULT_WARN (2L * 7L * 86400L) /* Two weeks */ 108 #define NO_SLEEP_EXIT 0 109 #define SLEEP_EXIT 5 110 111 /* 112 * This bounds the time given to login. Not a define so it can 113 * be patched on machines where it's too small. 114 */ 115 static u_int timeout = 300; 116 117 /* Buffer for signal handling of timeout */ 118 static jmp_buf timeout_buf; 119 120 struct passwd *pwd; 121 static int failures; 122 123 static char *envinit[1]; /* empty environment list */ 124 125 /* 126 * Command line flags and arguments 127 */ 128 static int fflag; /* -f: do not perform authentication */ 129 static int hflag; /* -h: login from remote host */ 130 static char *hostname; /* hostname from command line */ 131 static int pflag; /* -p: preserve environment */ 132 133 /* 134 * User name 135 */ 136 static char *username; /* user name */ 137 static char *olduser; /* previous user name */ 138 139 /* 140 * Prompts 141 */ 142 static char default_prompt[] = DEFAULT_PROMPT; 143 static const char *prompt; 144 static char default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT; 145 static const char *passwd_prompt; 146 147 static char *tty; 148 149 /* 150 * PAM data 151 */ 152 static pam_handle_t *pamh = NULL; 153 static struct pam_conv pamc = { openpam_ttyconv, NULL }; 154 static int pam_err; 155 static int pam_silent = PAM_SILENT; 156 static int pam_cred_established; 157 static int pam_session_established; 158 159 int 160 main(int argc, char *argv[]) 161 { 162 struct group *gr; 163 struct stat st; 164 int retries, backoff; 165 int ask, ch, cnt, quietlog, rootlogin, rval; 166 uid_t uid, euid; 167 gid_t egid; 168 char *term; 169 char *p, *ttyn; 170 char tname[sizeof(_PATH_TTY) + 10]; 171 char *arg0; 172 const char *tp; 173 const char *shell = NULL; 174 login_cap_t *lc = NULL; 175 login_cap_t *lc_user = NULL; 176 pid_t pid; 177 sigset_t mask, omask; 178 struct sigaction sa; 179 #ifdef USE_BSM_AUDIT 180 char auditsuccess = 1; 181 #endif 182 183 sa.sa_flags = SA_RESTART; 184 (void)sigfillset(&sa.sa_mask); 185 sa.sa_handler = SIG_IGN; 186 (void)sigaction(SIGQUIT, &sa, NULL); 187 (void)sigaction(SIGINT, &sa, NULL); 188 (void)sigaction(SIGHUP, &sa, NULL); 189 if (setjmp(timeout_buf)) { 190 if (failures) 191 badlogin(username); 192 (void)fprintf(stderr, "Login timed out after %d seconds\n", 193 timeout); 194 bail(NO_SLEEP_EXIT, 0); 195 } 196 sa.sa_handler = timedout; 197 (void)sigaction(SIGALRM, &sa, NULL); 198 (void)alarm(timeout); 199 (void)setpriority(PRIO_PROCESS, 0, 0); 200 201 openlog("login", LOG_ODELAY, LOG_AUTH); 202 203 uid = getuid(); 204 euid = geteuid(); 205 egid = getegid(); 206 207 while ((ch = getopt(argc, argv, "fh:p")) != -1) 208 switch (ch) { 209 case 'f': 210 fflag = 1; 211 break; 212 case 'h': 213 if (uid != 0) 214 errx(1, "-h option: %s", strerror(EPERM)); 215 if (strlen(optarg) >= MAXHOSTNAMELEN) 216 errx(1, "-h option: %s: exceeds maximum " 217 "hostname size", optarg); 218 hflag = 1; 219 hostname = optarg; 220 break; 221 case 'p': 222 pflag = 1; 223 break; 224 case '?': 225 default: 226 if (uid == 0) 227 syslog(LOG_ERR, "invalid flag %c", ch); 228 usage(); 229 } 230 argc -= optind; 231 argv += optind; 232 233 if (argc > 0) { 234 username = strdup(*argv); 235 if (username == NULL) 236 err(1, "strdup()"); 237 ask = 0; 238 } else { 239 ask = 1; 240 } 241 242 setproctitle("-%s", getprogname()); 243 244 closefrom(3); 245 246 /* 247 * Get current TTY 248 */ 249 ttyn = ttyname(STDIN_FILENO); 250 if (ttyn == NULL || *ttyn == '\0') { 251 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY); 252 ttyn = tname; 253 } 254 if (strncmp(ttyn, _PATH_DEV, sizeof _PATH_DEV - 1) == 0) 255 tty = ttyn + sizeof _PATH_DEV - 1; 256 else 257 tty = ttyn; 258 259 /* 260 * Get "login-retries" & "login-backoff" from default class 261 */ 262 lc = login_getclass(NULL); 263 prompt = login_getcapstr(lc, "login_prompt", 264 default_prompt, default_prompt); 265 passwd_prompt = login_getcapstr(lc, "passwd_prompt", 266 default_passwd_prompt, default_passwd_prompt); 267 retries = login_getcapnum(lc, "login-retries", 268 DEFAULT_RETRIES, DEFAULT_RETRIES); 269 backoff = login_getcapnum(lc, "login-backoff", 270 DEFAULT_BACKOFF, DEFAULT_BACKOFF); 271 login_close(lc); 272 lc = NULL; 273 274 /* 275 * Try to authenticate the user until we succeed or time out. 276 */ 277 for (cnt = 0;; ask = 1) { 278 if (ask) { 279 fflag = 0; 280 if (olduser != NULL) 281 free(olduser); 282 olduser = username; 283 username = getloginname(); 284 } 285 rootlogin = 0; 286 287 /* 288 * Note if trying multiple user names; log failures for 289 * previous user name, but don't bother logging one failure 290 * for nonexistent name (mistyped username). 291 */ 292 if (failures && strcmp(olduser, username) != 0) { 293 if (failures > (pwd ? 0 : 1)) 294 badlogin(olduser); 295 } 296 297 /* 298 * Load the PAM policy and set some variables 299 */ 300 pam_err = pam_start("login", username, &pamc, &pamh); 301 if (pam_err != PAM_SUCCESS) { 302 pam_syslog("pam_start()"); 303 #ifdef USE_BSM_AUDIT 304 au_login_fail("PAM Error", 1); 305 #endif 306 bail(NO_SLEEP_EXIT, 1); 307 } 308 pam_err = pam_set_item(pamh, PAM_TTY, tty); 309 if (pam_err != PAM_SUCCESS) { 310 pam_syslog("pam_set_item(PAM_TTY)"); 311 #ifdef USE_BSM_AUDIT 312 au_login_fail("PAM Error", 1); 313 #endif 314 bail(NO_SLEEP_EXIT, 1); 315 } 316 pam_err = pam_set_item(pamh, PAM_RHOST, hostname); 317 if (pam_err != PAM_SUCCESS) { 318 pam_syslog("pam_set_item(PAM_RHOST)"); 319 #ifdef USE_BSM_AUDIT 320 au_login_fail("PAM Error", 1); 321 #endif 322 bail(NO_SLEEP_EXIT, 1); 323 } 324 325 pwd = getpwnam(username); 326 if (pwd != NULL && pwd->pw_uid == 0) 327 rootlogin = 1; 328 329 /* 330 * If the -f option was specified and the caller is 331 * root or the caller isn't changing their uid, don't 332 * authenticate. 333 */ 334 if (pwd != NULL && fflag && 335 (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) { 336 /* already authenticated */ 337 rval = 0; 338 #ifdef USE_BSM_AUDIT 339 auditsuccess = 0; /* opened a terminal window only */ 340 #endif 341 } else { 342 fflag = 0; 343 (void)setpriority(PRIO_PROCESS, 0, -4); 344 rval = auth_pam(); 345 (void)setpriority(PRIO_PROCESS, 0, 0); 346 } 347 348 if (pwd && rval == 0) 349 break; 350 351 pam_cleanup(); 352 353 /* 354 * We are not exiting here, but this corresponds to a failed 355 * login event, so set exitstatus to 1. 356 */ 357 #ifdef USE_BSM_AUDIT 358 au_login_fail("Login incorrect", 1); 359 #endif 360 361 (void)printf("Login incorrect\n"); 362 failures++; 363 364 pwd = NULL; 365 366 /* 367 * Allow up to 'retry' (10) attempts, but start 368 * backing off after 'backoff' (3) attempts. 369 */ 370 if (++cnt > backoff) { 371 if (cnt >= retries) { 372 badlogin(username); 373 bail(SLEEP_EXIT, 1); 374 } 375 sleep((u_int)((cnt - backoff) * 5)); 376 } 377 } 378 379 /* committed to login -- turn off timeout */ 380 (void)alarm((u_int)0); 381 382 (void)sigemptyset(&mask); 383 (void)sigaddset(&mask, SIGHUP); 384 (void)sigaddset(&mask, SIGTERM); 385 (void)sigprocmask(SIG_BLOCK, &mask, &omask); 386 sa.sa_handler = bail_sig; 387 (void)sigaction(SIGHUP, &sa, NULL); 388 (void)sigaction(SIGTERM, &sa, NULL); 389 390 endpwent(); 391 392 #ifdef USE_BSM_AUDIT 393 /* Audit successful login. */ 394 if (auditsuccess) 395 au_login_success(); 396 #endif 397 398 /* 399 * This needs to happen before login_getpwclass to support 400 * home directories on GSS-API authenticated NFS where the 401 * kerberos credentials need to be saved so that the kernel 402 * can authenticate to the NFS server. 403 */ 404 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); 405 if (pam_err != PAM_SUCCESS) { 406 pam_syslog("pam_setcred()"); 407 bail(NO_SLEEP_EXIT, 1); 408 } 409 pam_cred_established = 1; 410 411 /* 412 * Establish the login class. 413 */ 414 lc = login_getpwclass(pwd); 415 lc_user = login_getuserclass(pwd); 416 417 if (!(quietlog = login_getcapbool(lc_user, "hushlogin", 0))) 418 quietlog = login_getcapbool(lc, "hushlogin", 0); 419 420 /* 421 * Switching needed for NFS with root access disabled. 422 * 423 * XXX: This change fails to modify the additional groups for the 424 * process, and as such, may restrict rights normally granted 425 * through those groups. 426 */ 427 (void)setegid(pwd->pw_gid); 428 (void)seteuid(rootlogin ? 0 : pwd->pw_uid); 429 if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) { 430 if (login_getcapbool(lc, "requirehome", 0)) 431 refused("Home directory not available", "HOMEDIR", 1); 432 if (chdir("/") < 0) 433 refused("Cannot find root directory", "ROOTDIR", 1); 434 if (!quietlog || *pwd->pw_dir) 435 printf("No home directory.\nLogging in with home = \"/\".\n"); 436 pwd->pw_dir = strdup("/"); 437 if (pwd->pw_dir == NULL) { 438 syslog(LOG_NOTICE, "strdup(): %m"); 439 bail(SLEEP_EXIT, 1); 440 } 441 } 442 (void)seteuid(euid); 443 (void)setegid(egid); 444 if (!quietlog) { 445 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; 446 if (!quietlog) 447 pam_silent = 0; 448 } 449 450 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); 451 if (*pwd->pw_shell == '\0') 452 pwd->pw_shell = strdup(_PATH_BSHELL); 453 if (pwd->pw_shell == NULL) { 454 syslog(LOG_NOTICE, "strdup(): %m"); 455 bail(SLEEP_EXIT, 1); 456 } 457 if (*shell == '\0') /* Not overridden */ 458 shell = pwd->pw_shell; 459 if ((shell = strdup(shell)) == NULL) { 460 syslog(LOG_NOTICE, "strdup(): %m"); 461 bail(SLEEP_EXIT, 1); 462 } 463 464 /* 465 * Set device protections, depending on what terminal the 466 * user is logged in. This feature is used on Suns to give 467 * console users better privacy. 468 */ 469 login_fbtab(tty, pwd->pw_uid, pwd->pw_gid); 470 471 /* 472 * Clear flags of the tty. None should be set, and when the 473 * user sets them otherwise, this can cause the chown to fail. 474 * Since it isn't clear that flags are useful on character 475 * devices, we just clear them. 476 * 477 * We don't log in the case of EOPNOTSUPP because dev might be 478 * on NFS, which doesn't support chflags. 479 * 480 * We don't log in the EROFS because that means that /dev is on 481 * a read only file system and we assume that the permissions there 482 * are sane. 483 */ 484 if (ttyn != tname && chflags(ttyn, 0)) 485 if (errno != EOPNOTSUPP && errno != EROFS) 486 syslog(LOG_ERR, "chflags(%s): %m", ttyn); 487 if (ttyn != tname && chown(ttyn, pwd->pw_uid, 488 (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid)) 489 if (errno != EROFS) 490 syslog(LOG_ERR, "chown(%s): %m", ttyn); 491 492 #ifdef LOGALL 493 /* 494 * Syslog each successful login, so we don't have to watch 495 * hundreds of wtmp or lastlogin files. 496 */ 497 if (hflag) 498 syslog(LOG_INFO, "login from %s on %s as %s", 499 hostname, tty, pwd->pw_name); 500 else 501 syslog(LOG_INFO, "login on %s as %s", 502 tty, pwd->pw_name); 503 #endif 504 505 /* 506 * If fflag is on, assume caller/authenticator has logged root 507 * login. 508 */ 509 if (rootlogin && fflag == 0) { 510 if (hflag) 511 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s", 512 username, tty, hostname); 513 else 514 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s", 515 username, tty); 516 } 517 518 /* 519 * Destroy environment unless user has requested its 520 * preservation - but preserve TERM in all cases 521 */ 522 term = getenv("TERM"); 523 if (!pflag) 524 environ = envinit; 525 if (term != NULL) 526 setenv("TERM", term, 0); 527 528 /* 529 * PAM modules might add supplementary groups during pam_setcred(). 530 */ 531 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { 532 syslog(LOG_ERR, "setusercontext() failed - exiting"); 533 bail(NO_SLEEP_EXIT, 1); 534 } 535 536 pam_err = pam_setcred(pamh, pam_silent|PAM_REINITIALIZE_CRED); 537 if (pam_err != PAM_SUCCESS) { 538 pam_syslog("pam_setcred()"); 539 bail(NO_SLEEP_EXIT, 1); 540 } 541 542 pam_err = pam_open_session(pamh, pam_silent); 543 if (pam_err != PAM_SUCCESS) { 544 pam_syslog("pam_open_session()"); 545 bail(NO_SLEEP_EXIT, 1); 546 } 547 pam_session_established = 1; 548 549 /* 550 * We must fork() before setuid() because we need to call 551 * pam_close_session() as root. 552 */ 553 pid = fork(); 554 if (pid < 0) { 555 err(1, "fork"); 556 } else if (pid != 0) { 557 /* 558 * Parent: wait for child to finish, then clean up 559 * session. 560 * 561 * If we get SIGHUP or SIGTERM, clean up the session 562 * and exit right away. This will make the terminal 563 * inaccessible and send SIGHUP to the foreground 564 * process group. 565 */ 566 int status; 567 setproctitle("-%s [pam]", getprogname()); 568 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 569 waitpid(pid, &status, 0); 570 (void)sigprocmask(SIG_BLOCK, &mask, NULL); 571 bail(NO_SLEEP_EXIT, 0); 572 } 573 574 /* 575 * NOTICE: We are now in the child process! 576 */ 577 578 /* 579 * Add any environment variables the PAM modules may have set. 580 */ 581 export_pam_environment(); 582 583 /* 584 * We're done with PAM now; our parent will deal with the rest. 585 */ 586 pam_end(pamh, 0); 587 pamh = NULL; 588 589 /* 590 * We don't need to be root anymore, so set the login name and 591 * the UID. 592 */ 593 if (setlogin(username) != 0) { 594 syslog(LOG_ERR, "setlogin(%s): %m - exiting", username); 595 bail(NO_SLEEP_EXIT, 1); 596 } 597 if (setusercontext(lc, pwd, pwd->pw_uid, 598 LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) { 599 syslog(LOG_ERR, "setusercontext() failed - exiting"); 600 exit(1); 601 } 602 603 (void)setenv("SHELL", pwd->pw_shell, 1); 604 (void)setenv("HOME", pwd->pw_dir, 1); 605 /* Overwrite "term" from login.conf(5) for any known TERM */ 606 if (term == NULL && (tp = stypeof(tty)) != NULL) 607 (void)setenv("TERM", tp, 1); 608 else 609 (void)setenv("TERM", TERM_UNKNOWN, 0); 610 (void)setenv("LOGNAME", username, 1); 611 (void)setenv("USER", username, 1); 612 (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0); 613 614 if (!quietlog) { 615 const char *cw; 616 617 cw = login_getcapstr(lc, "welcome", NULL, NULL); 618 if (cw != NULL && access(cw, F_OK) == 0) 619 motd(cw); 620 else 621 motd(_PATH_MOTDFILE); 622 623 if (login_getcapbool(lc_user, "nocheckmail", 0) == 0 && 624 login_getcapbool(lc, "nocheckmail", 0) == 0) { 625 char *cx; 626 627 /* $MAIL may have been set by class. */ 628 cx = getenv("MAIL"); 629 if (cx == NULL) { 630 asprintf(&cx, "%s/%s", 631 _PATH_MAILDIR, pwd->pw_name); 632 } 633 if (cx && stat(cx, &st) == 0 && st.st_size != 0) 634 (void)printf("You have %smail.\n", 635 (st.st_mtime > st.st_atime) ? "new " : ""); 636 if (getenv("MAIL") == NULL) 637 free(cx); 638 } 639 } 640 641 login_close(lc_user); 642 login_close(lc); 643 644 sa.sa_handler = SIG_DFL; 645 (void)sigaction(SIGALRM, &sa, NULL); 646 (void)sigaction(SIGQUIT, &sa, NULL); 647 (void)sigaction(SIGINT, &sa, NULL); 648 (void)sigaction(SIGTERM, &sa, NULL); 649 (void)sigaction(SIGHUP, &sa, NULL); 650 sa.sa_handler = SIG_IGN; 651 (void)sigaction(SIGTSTP, &sa, NULL); 652 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 653 654 /* 655 * Login shells have a leading '-' in front of argv[0] 656 */ 657 p = strrchr(pwd->pw_shell, '/'); 658 if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) { 659 syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size", 660 username); 661 errx(1, "shell exceeds maximum pathname size"); 662 } else if (arg0 == NULL) { 663 err(1, "asprintf()"); 664 } 665 666 execlp(shell, arg0, (char *)0); 667 err(1, "%s", shell); 668 669 /* 670 * That's it, folks! 671 */ 672 } 673 674 /* 675 * Attempt to authenticate the user using PAM. Returns 0 if the user is 676 * authenticated, or 1 if not authenticated. If some sort of PAM system 677 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this 678 * function returns -1. This can be used as an indication that we should 679 * fall back to a different authentication mechanism. 680 */ 681 static int 682 auth_pam(void) 683 { 684 const char *tmpl_user; 685 const void *item; 686 int rval; 687 688 pam_err = pam_authenticate(pamh, pam_silent); 689 switch (pam_err) { 690 691 case PAM_SUCCESS: 692 /* 693 * With PAM we support the concept of a "template" 694 * user. The user enters a login name which is 695 * authenticated by PAM, usually via a remote service 696 * such as RADIUS or TACACS+. If authentication 697 * succeeds, a different but related "template" name 698 * is used for setting the credentials, shell, and 699 * home directory. The name the user enters need only 700 * exist on the remote authentication server, but the 701 * template name must be present in the local password 702 * database. 703 * 704 * This is supported by two various mechanisms in the 705 * individual modules. However, from the application's 706 * point of view, the template user is always passed 707 * back as a changed value of the PAM_USER item. 708 */ 709 pam_err = pam_get_item(pamh, PAM_USER, &item); 710 if (pam_err == PAM_SUCCESS) { 711 tmpl_user = (const char *)item; 712 if (strcmp(username, tmpl_user) != 0) 713 pwd = getpwnam(tmpl_user); 714 } else { 715 pam_syslog("pam_get_item(PAM_USER)"); 716 } 717 rval = 0; 718 break; 719 720 case PAM_AUTH_ERR: 721 case PAM_USER_UNKNOWN: 722 case PAM_MAXTRIES: 723 rval = 1; 724 break; 725 726 default: 727 pam_syslog("pam_authenticate()"); 728 rval = -1; 729 break; 730 } 731 732 if (rval == 0) { 733 pam_err = pam_acct_mgmt(pamh, pam_silent); 734 switch (pam_err) { 735 case PAM_SUCCESS: 736 break; 737 case PAM_NEW_AUTHTOK_REQD: 738 pam_err = pam_chauthtok(pamh, 739 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); 740 if (pam_err != PAM_SUCCESS) { 741 pam_syslog("pam_chauthtok()"); 742 rval = 1; 743 } 744 break; 745 default: 746 pam_syslog("pam_acct_mgmt()"); 747 rval = 1; 748 break; 749 } 750 } 751 752 if (rval != 0) { 753 pam_end(pamh, pam_err); 754 pamh = NULL; 755 } 756 return (rval); 757 } 758 759 /* 760 * Export any environment variables PAM modules may have set 761 */ 762 static void 763 export_pam_environment(void) 764 { 765 char **pam_env; 766 char **pp; 767 768 pam_env = pam_getenvlist(pamh); 769 if (pam_env != NULL) { 770 for (pp = pam_env; *pp != NULL; pp++) { 771 (void)export(*pp); 772 free(*pp); 773 } 774 } 775 } 776 777 /* 778 * Perform sanity checks on an environment variable: 779 * - Make sure there is an '=' in the string. 780 * - Make sure the string doesn't run on too long. 781 * - Do not export certain variables. This list was taken from the 782 * Solaris pam_putenv(3) man page. 783 * Then export it. 784 */ 785 static int 786 export(const char *s) 787 { 788 static const char *noexport[] = { 789 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH", 790 "IFS", "PATH", NULL 791 }; 792 char *p; 793 const char **pp; 794 size_t n; 795 796 if (strlen(s) > 1024 || (p = strchr(s, '=')) == NULL) 797 return (0); 798 if (strncmp(s, "LD_", 3) == 0) 799 return (0); 800 for (pp = noexport; *pp != NULL; pp++) { 801 n = strlen(*pp); 802 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 803 return (0); 804 } 805 *p = '\0'; 806 (void)setenv(s, p + 1, 1); 807 *p = '='; 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