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 #if 0 44 #ifndef lint 45 static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94"; 46 #endif 47 #endif 48 49 #include <sys/cdefs.h> 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 <login_cap.h> 67 #include <pwd.h> 68 #include <setjmp.h> 69 #include <signal.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <syslog.h> 74 #include <ttyent.h> 75 #include <unistd.h> 76 77 #include <security/pam_appl.h> 78 #include <security/openpam.h> 79 80 #include "login.h" 81 #include "pathnames.h" 82 83 static int auth_pam(void); 84 static void bail(int, int); 85 static void bail_internal(int, int, int); 86 static int export(const char *); 87 static void export_pam_environment(void); 88 static int motd(const char *); 89 static void badlogin(char *); 90 static char *getloginname(void); 91 static void pam_syslog(const char *); 92 static void pam_cleanup(void); 93 static void refused(const char *, const char *, int); 94 static const char *stypeof(char *); 95 static void sigint(int); 96 static void timedout(int); 97 static void bail_sig(int); 98 static void usage(void); 99 100 #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 0 108 #define SLEEP_EXIT 5 109 110 /* 111 * This bounds the time given to login. Not a define so it can 112 * be patched on machines where it's too small. 113 */ 114 static u_int timeout = 300; 115 116 /* Buffer for signal handling of timeout */ 117 static jmp_buf timeout_buf; 118 119 struct passwd *pwd; 120 static int failures; 121 122 static char *envinit[1]; /* empty environment list */ 123 124 /* 125 * Command line flags and arguments 126 */ 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 */ 131 132 /* 133 * User name 134 */ 135 static char *username; /* user name */ 136 static char *olduser; /* previous user name */ 137 138 /* 139 * Prompts 140 */ 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; 145 146 static char *tty; 147 148 /* 149 * PAM data 150 */ 151 static pam_handle_t *pamh = NULL; 152 static struct pam_conv pamc = { openpam_ttyconv, NULL }; 153 static int pam_err; 154 static int pam_silent = PAM_SILENT; 155 static int pam_cred_established; 156 static int pam_session_established; 157 158 int 159 main(int argc, char *argv[]) 160 { 161 struct group *gr; 162 struct stat st; 163 int retries, backoff; 164 int ask, ch, cnt, quietlog, rootlogin, rval; 165 uid_t uid, euid; 166 gid_t egid; 167 char *term; 168 char *p, *ttyn; 169 char tname[sizeof(_PATH_TTY) + 10]; 170 char *arg0; 171 const char *tp; 172 const char *shell = NULL; 173 login_cap_t *lc = NULL; 174 login_cap_t *lc_user = NULL; 175 pid_t pid; 176 sigset_t mask, omask; 177 struct sigaction sa; 178 #ifdef USE_BSM_AUDIT 179 char auditsuccess = 1; 180 #endif 181 182 sa.sa_flags = SA_RESTART; 183 (void)sigfillset(&sa.sa_mask); 184 sa.sa_handler = SIG_IGN; 185 (void)sigaction(SIGQUIT, &sa, NULL); 186 (void)sigaction(SIGINT, &sa, NULL); 187 (void)sigaction(SIGHUP, &sa, NULL); 188 if (setjmp(timeout_buf)) { 189 if (failures) 190 badlogin(username); 191 (void)fprintf(stderr, "Login timed out after %d seconds\n", 192 timeout); 193 bail(NO_SLEEP_EXIT, 0); 194 } 195 sa.sa_handler = timedout; 196 (void)sigaction(SIGALRM, &sa, NULL); 197 (void)alarm(timeout); 198 (void)setpriority(PRIO_PROCESS, 0, 0); 199 200 openlog("login", LOG_CONS, LOG_AUTH); 201 202 uid = getuid(); 203 euid = geteuid(); 204 egid = getegid(); 205 206 while ((ch = getopt(argc, argv, "fh:p")) != -1) 207 switch (ch) { 208 case 'f': 209 fflag = 1; 210 break; 211 case 'h': 212 if (uid != 0) 213 errx(1, "-h option: %s", strerror(EPERM)); 214 if (strlen(optarg) >= MAXHOSTNAMELEN) 215 errx(1, "-h option: %s: exceeds maximum " 216 "hostname size", optarg); 217 hflag = 1; 218 hostname = optarg; 219 break; 220 case 'p': 221 pflag = 1; 222 break; 223 case '?': 224 default: 225 if (uid == 0) 226 syslog(LOG_ERR, "invalid flag %c", ch); 227 usage(); 228 } 229 argc -= optind; 230 argv += optind; 231 232 if (argc > 0) { 233 username = strdup(*argv); 234 if (username == NULL) 235 err(1, "strdup()"); 236 ask = 0; 237 } else { 238 ask = 1; 239 } 240 241 setproctitle("-%s", getprogname()); 242 243 closefrom(3); 244 245 /* 246 * Get current TTY 247 */ 248 ttyn = ttyname(STDIN_FILENO); 249 if (ttyn == NULL || *ttyn == '\0') { 250 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY); 251 ttyn = tname; 252 } 253 if (strncmp(ttyn, _PATH_DEV, sizeof _PATH_DEV - 1) == 0) 254 tty = ttyn + sizeof _PATH_DEV - 1; 255 else 256 tty = ttyn; 257 258 /* 259 * Get "login-retries" & "login-backoff" from default class 260 */ 261 lc = login_getclass(NULL); 262 prompt = login_getcapstr(lc, "login_prompt", 263 default_prompt, default_prompt); 264 passwd_prompt = login_getcapstr(lc, "passwd_prompt", 265 default_passwd_prompt, default_passwd_prompt); 266 retries = login_getcapnum(lc, "login-retries", 267 DEFAULT_RETRIES, DEFAULT_RETRIES); 268 backoff = login_getcapnum(lc, "login-backoff", 269 DEFAULT_BACKOFF, DEFAULT_BACKOFF); 270 login_close(lc); 271 lc = NULL; 272 273 /* 274 * Try to authenticate the user until we succeed or time out. 275 */ 276 for (cnt = 0;; ask = 1) { 277 if (ask) { 278 fflag = 0; 279 if (olduser != NULL) 280 free(olduser); 281 olduser = username; 282 username = getloginname(); 283 } 284 rootlogin = 0; 285 286 /* 287 * Note if trying multiple user names; log failures for 288 * previous user name, but don't bother logging one failure 289 * for nonexistent name (mistyped username). 290 */ 291 if (failures && strcmp(olduser, username) != 0) { 292 if (failures > (pwd ? 0 : 1)) 293 badlogin(olduser); 294 } 295 296 /* 297 * Load the PAM policy and set some variables 298 */ 299 pam_err = pam_start("login", username, &pamc, &pamh); 300 if (pam_err != PAM_SUCCESS) { 301 pam_syslog("pam_start()"); 302 #ifdef USE_BSM_AUDIT 303 au_login_fail("PAM Error", 1); 304 #endif 305 bail(NO_SLEEP_EXIT, 1); 306 } 307 pam_err = pam_set_item(pamh, PAM_TTY, tty); 308 if (pam_err != PAM_SUCCESS) { 309 pam_syslog("pam_set_item(PAM_TTY)"); 310 #ifdef USE_BSM_AUDIT 311 au_login_fail("PAM Error", 1); 312 #endif 313 bail(NO_SLEEP_EXIT, 1); 314 } 315 pam_err = pam_set_item(pamh, PAM_RHOST, hostname); 316 if (pam_err != PAM_SUCCESS) { 317 pam_syslog("pam_set_item(PAM_RHOST)"); 318 #ifdef USE_BSM_AUDIT 319 au_login_fail("PAM Error", 1); 320 #endif 321 bail(NO_SLEEP_EXIT, 1); 322 } 323 324 pwd = getpwnam(username); 325 if (pwd != NULL && pwd->pw_uid == 0) 326 rootlogin = 1; 327 328 /* 329 * If the -f option was specified and the caller is 330 * root or the caller isn't changing their uid, don't 331 * authenticate. 332 */ 333 if (pwd != NULL && fflag && 334 (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) { 335 /* already authenticated */ 336 rval = 0; 337 #ifdef USE_BSM_AUDIT 338 auditsuccess = 0; /* opened a terminal window only */ 339 #endif 340 } else { 341 fflag = 0; 342 (void)setpriority(PRIO_PROCESS, 0, -4); 343 rval = auth_pam(); 344 (void)setpriority(PRIO_PROCESS, 0, 0); 345 } 346 347 if (pwd && rval == 0) 348 break; 349 350 pam_cleanup(); 351 352 /* 353 * We are not exiting here, but this corresponds to a failed 354 * login event, so set exitstatus to 1. 355 */ 356 #ifdef USE_BSM_AUDIT 357 au_login_fail("Login incorrect", 1); 358 #endif 359 360 (void)printf("Login incorrect\n"); 361 failures++; 362 363 pwd = NULL; 364 365 /* 366 * Allow up to 'retry' (10) attempts, but start 367 * backing off after 'backoff' (3) attempts. 368 */ 369 if (++cnt > backoff) { 370 if (cnt >= retries) { 371 badlogin(username); 372 bail(SLEEP_EXIT, 1); 373 } 374 sleep((u_int)((cnt - backoff) * 5)); 375 } 376 } 377 378 /* committed to login -- turn off timeout */ 379 (void)alarm((u_int)0); 380 381 (void)sigemptyset(&mask); 382 (void)sigaddset(&mask, SIGHUP); 383 (void)sigaddset(&mask, SIGTERM); 384 (void)sigprocmask(SIG_BLOCK, &mask, &omask); 385 sa.sa_handler = bail_sig; 386 (void)sigaction(SIGHUP, &sa, NULL); 387 (void)sigaction(SIGTERM, &sa, NULL); 388 389 endpwent(); 390 391 #ifdef USE_BSM_AUDIT 392 /* Audit successful login. */ 393 if (auditsuccess) 394 au_login_success(); 395 #endif 396 397 /* 398 * This needs to happen before login_getpwclass to support 399 * home directories on GSS-API authenticated NFS where the 400 * kerberos credentials need to be saved so that the kernel 401 * can authenticate to the NFS server. 402 */ 403 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); 404 if (pam_err != PAM_SUCCESS) { 405 pam_syslog("pam_setcred()"); 406 bail(NO_SLEEP_EXIT, 1); 407 } 408 pam_cred_established = 1; 409 410 /* 411 * Establish the login class. 412 */ 413 lc = login_getpwclass(pwd); 414 lc_user = login_getuserclass(pwd); 415 416 if (!(quietlog = login_getcapbool(lc_user, "hushlogin", 0))) 417 quietlog = login_getcapbool(lc, "hushlogin", 0); 418 419 /* 420 * Switching needed for NFS with root access disabled. 421 * 422 * XXX: This change fails to modify the additional groups for the 423 * process, and as such, may restrict rights normally granted 424 * through those groups. 425 */ 426 (void)setegid(pwd->pw_gid); 427 (void)seteuid(rootlogin ? 0 : pwd->pw_uid); 428 if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) { 429 if (login_getcapbool(lc, "requirehome", 0)) 430 refused("Home directory not available", "HOMEDIR", 1); 431 if (chdir("/") < 0) 432 refused("Cannot find root directory", "ROOTDIR", 1); 433 if (!quietlog || *pwd->pw_dir) 434 printf("No home directory.\nLogging in with home = \"/\".\n"); 435 pwd->pw_dir = strdup("/"); 436 if (pwd->pw_dir == NULL) { 437 syslog(LOG_NOTICE, "strdup(): %m"); 438 bail(SLEEP_EXIT, 1); 439 } 440 } 441 (void)seteuid(euid); 442 (void)setegid(egid); 443 if (!quietlog) { 444 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; 445 if (!quietlog) 446 pam_silent = 0; 447 } 448 449 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); 450 if (*pwd->pw_shell == '\0') 451 pwd->pw_shell = strdup(_PATH_BSHELL); 452 if (pwd->pw_shell == NULL) { 453 syslog(LOG_NOTICE, "strdup(): %m"); 454 bail(SLEEP_EXIT, 1); 455 } 456 if (*shell == '\0') /* Not overridden */ 457 shell = pwd->pw_shell; 458 if ((shell = strdup(shell)) == NULL) { 459 syslog(LOG_NOTICE, "strdup(): %m"); 460 bail(SLEEP_EXIT, 1); 461 } 462 463 /* 464 * Set device protections, depending on what terminal the 465 * user is logged in. This feature is used on Suns to give 466 * console users better privacy. 467 */ 468 login_fbtab(tty, pwd->pw_uid, pwd->pw_gid); 469 470 /* 471 * Clear flags of the tty. None should be set, and when the 472 * user sets them otherwise, this can cause the chown to fail. 473 * Since it isn't clear that flags are useful on character 474 * devices, we just clear them. 475 * 476 * We don't log in the case of EOPNOTSUPP because dev might be 477 * on NFS, which doesn't support chflags. 478 * 479 * We don't log in the EROFS because that means that /dev is on 480 * a read only file system and we assume that the permissions there 481 * are sane. 482 */ 483 if (ttyn != tname && chflags(ttyn, 0)) 484 if (errno != EOPNOTSUPP && errno != EROFS) 485 syslog(LOG_ERR, "chflags(%s): %m", ttyn); 486 if (ttyn != tname && chown(ttyn, pwd->pw_uid, 487 (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid)) 488 if (errno != EROFS) 489 syslog(LOG_ERR, "chown(%s): %m", ttyn); 490 491 #ifdef LOGALL 492 /* 493 * Syslog each successful login, so we don't have to watch 494 * hundreds of wtmp or lastlogin files. 495 */ 496 if (hflag) 497 syslog(LOG_INFO, "login from %s on %s as %s", 498 hostname, tty, pwd->pw_name); 499 else 500 syslog(LOG_INFO, "login on %s as %s", 501 tty, pwd->pw_name); 502 #endif 503 504 /* 505 * If fflag is on, assume caller/authenticator has logged root 506 * login. 507 */ 508 if (rootlogin && fflag == 0) { 509 if (hflag) 510 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s", 511 username, tty, hostname); 512 else 513 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s", 514 username, tty); 515 } 516 517 /* 518 * Destroy environment unless user has requested its 519 * preservation - but preserve TERM in all cases 520 */ 521 term = getenv("TERM"); 522 if (!pflag) 523 environ = envinit; 524 if (term != NULL) 525 setenv("TERM", term, 0); 526 527 /* 528 * PAM modules might add supplementary groups during pam_setcred(). 529 */ 530 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { 531 syslog(LOG_ERR, "setusercontext() failed - exiting"); 532 bail(NO_SLEEP_EXIT, 1); 533 } 534 535 pam_err = pam_setcred(pamh, pam_silent|PAM_REINITIALIZE_CRED); 536 if (pam_err != PAM_SUCCESS) { 537 pam_syslog("pam_setcred()"); 538 bail(NO_SLEEP_EXIT, 1); 539 } 540 541 pam_err = pam_open_session(pamh, pam_silent); 542 if (pam_err != PAM_SUCCESS) { 543 pam_syslog("pam_open_session()"); 544 bail(NO_SLEEP_EXIT, 1); 545 } 546 pam_session_established = 1; 547 548 /* 549 * We must fork() before setuid() because we need to call 550 * pam_close_session() as root. 551 */ 552 pid = fork(); 553 if (pid < 0) { 554 err(1, "fork"); 555 } else if (pid != 0) { 556 /* 557 * Parent: wait for child to finish, then clean up 558 * session. 559 * 560 * If we get SIGHUP or SIGTERM, clean up the session 561 * and exit right away. This will make the terminal 562 * inaccessible and send SIGHUP to the foreground 563 * process group. 564 */ 565 int status; 566 setproctitle("-%s [pam]", getprogname()); 567 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 568 waitpid(pid, &status, 0); 569 (void)sigprocmask(SIG_BLOCK, &mask, NULL); 570 bail(NO_SLEEP_EXIT, 0); 571 } 572 573 /* 574 * NOTICE: We are now in the child process! 575 */ 576 577 /* 578 * Add any environment variables the PAM modules may have set. 579 */ 580 export_pam_environment(); 581 582 /* 583 * We're done with PAM now; our parent will deal with the rest. 584 */ 585 pam_end(pamh, 0); 586 pamh = NULL; 587 588 /* 589 * We don't need to be root anymore, so set the login name and 590 * the UID. 591 */ 592 if (setlogin(username) != 0) { 593 syslog(LOG_ERR, "setlogin(%s): %m - exiting", username); 594 bail(NO_SLEEP_EXIT, 1); 595 } 596 if (setusercontext(lc, pwd, pwd->pw_uid, 597 LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) { 598 syslog(LOG_ERR, "setusercontext() failed - exiting"); 599 exit(1); 600 } 601 602 (void)setenv("SHELL", pwd->pw_shell, 1); 603 (void)setenv("HOME", pwd->pw_dir, 1); 604 /* Overwrite "term" from login.conf(5) for any known TERM */ 605 if (term == NULL && (tp = stypeof(tty)) != NULL) 606 (void)setenv("TERM", tp, 1); 607 else 608 (void)setenv("TERM", TERM_UNKNOWN, 0); 609 (void)setenv("LOGNAME", username, 1); 610 (void)setenv("USER", username, 1); 611 (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0); 612 613 if (!quietlog) { 614 const char *cw; 615 616 cw = login_getcapstr(lc, "welcome", NULL, NULL); 617 if (cw != NULL && access(cw, F_OK) == 0) 618 motd(cw); 619 else 620 motd(_PATH_MOTDFILE); 621 622 if (login_getcapbool(lc_user, "nocheckmail", 0) == 0 && 623 login_getcapbool(lc, "nocheckmail", 0) == 0) { 624 char *cx; 625 626 /* $MAIL may have been set by class. */ 627 cx = getenv("MAIL"); 628 if (cx == NULL) { 629 asprintf(&cx, "%s/%s", 630 _PATH_MAILDIR, pwd->pw_name); 631 } 632 if (cx && stat(cx, &st) == 0 && st.st_size != 0) 633 (void)printf("You have %smail.\n", 634 (st.st_mtime > st.st_atime) ? "new " : ""); 635 if (getenv("MAIL") == NULL) 636 free(cx); 637 } 638 } 639 640 login_close(lc_user); 641 login_close(lc); 642 643 sa.sa_handler = SIG_DFL; 644 (void)sigaction(SIGALRM, &sa, NULL); 645 (void)sigaction(SIGQUIT, &sa, NULL); 646 (void)sigaction(SIGINT, &sa, NULL); 647 (void)sigaction(SIGTERM, &sa, NULL); 648 (void)sigaction(SIGHUP, &sa, NULL); 649 sa.sa_handler = SIG_IGN; 650 (void)sigaction(SIGTSTP, &sa, NULL); 651 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 652 653 /* 654 * Login shells have a leading '-' in front of argv[0] 655 */ 656 p = strrchr(pwd->pw_shell, '/'); 657 if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) { 658 syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size", 659 username); 660 errx(1, "shell exceeds maximum pathname size"); 661 } else if (arg0 == NULL) { 662 err(1, "asprintf()"); 663 } 664 665 execlp(shell, arg0, (char *)0); 666 err(1, "%s", shell); 667 668 /* 669 * That's it, folks! 670 */ 671 } 672 673 /* 674 * Attempt to authenticate the user using PAM. Returns 0 if the user is 675 * authenticated, or 1 if not authenticated. If some sort of PAM system 676 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this 677 * function returns -1. This can be used as an indication that we should 678 * fall back to a different authentication mechanism. 679 */ 680 static int 681 auth_pam(void) 682 { 683 const char *tmpl_user; 684 const void *item; 685 int rval; 686 687 pam_err = pam_authenticate(pamh, pam_silent); 688 switch (pam_err) { 689 690 case PAM_SUCCESS: 691 /* 692 * With PAM we support the concept of a "template" 693 * user. The user enters a login name which is 694 * authenticated by PAM, usually via a remote service 695 * such as RADIUS or TACACS+. If authentication 696 * succeeds, a different but related "template" name 697 * is used for setting the credentials, shell, and 698 * home directory. The name the user enters need only 699 * exist on the remote authentication server, but the 700 * template name must be present in the local password 701 * database. 702 * 703 * This is supported by two various mechanisms in the 704 * individual modules. However, from the application's 705 * point of view, the template user is always passed 706 * back as a changed value of the PAM_USER item. 707 */ 708 pam_err = pam_get_item(pamh, PAM_USER, &item); 709 if (pam_err == PAM_SUCCESS) { 710 tmpl_user = (const char *)item; 711 if (strcmp(username, tmpl_user) != 0) 712 pwd = getpwnam(tmpl_user); 713 } else { 714 pam_syslog("pam_get_item(PAM_USER)"); 715 } 716 rval = 0; 717 break; 718 719 case PAM_AUTH_ERR: 720 case PAM_USER_UNKNOWN: 721 case PAM_MAXTRIES: 722 rval = 1; 723 break; 724 725 default: 726 pam_syslog("pam_authenticate()"); 727 rval = -1; 728 break; 729 } 730 731 if (rval == 0) { 732 pam_err = pam_acct_mgmt(pamh, pam_silent); 733 switch (pam_err) { 734 case PAM_SUCCESS: 735 break; 736 case PAM_NEW_AUTHTOK_REQD: 737 pam_err = pam_chauthtok(pamh, 738 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); 739 if (pam_err != PAM_SUCCESS) { 740 pam_syslog("pam_chauthtok()"); 741 rval = 1; 742 } 743 break; 744 default: 745 pam_syslog("pam_acct_mgmt()"); 746 rval = 1; 747 break; 748 } 749 } 750 751 if (rval != 0) { 752 pam_end(pamh, pam_err); 753 pamh = NULL; 754 } 755 return (rval); 756 } 757 758 /* 759 * Export any environment variables PAM modules may have set 760 */ 761 static void 762 export_pam_environment(void) 763 { 764 char **pam_env; 765 char **pp; 766 767 pam_env = pam_getenvlist(pamh); 768 if (pam_env != NULL) { 769 for (pp = pam_env; *pp != NULL; pp++) { 770 (void)export(*pp); 771 free(*pp); 772 } 773 } 774 } 775 776 /* 777 * Perform sanity checks on an environment variable: 778 * - Make sure there is an '=' in the string. 779 * - Make sure the string doesn't run on too long. 780 * - Do not export certain variables. This list was taken from the 781 * Solaris pam_putenv(3) man page. 782 * Then export it. 783 */ 784 static int 785 export(const char *s) 786 { 787 static const char *noexport[] = { 788 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH", 789 "IFS", "PATH", NULL 790 }; 791 char *p; 792 const char **pp; 793 size_t n; 794 int rv; 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 rv = setenv(s, p + 1, 1); 807 *p = '='; 808 if (rv == -1) 809 return (0); 810 return (1); 811 } 812 813 static void 814 usage(void) 815 { 816 817 (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n"); 818 exit(1); 819 } 820 821 /* 822 * Prompt user and read login name from stdin. 823 */ 824 static char * 825 getloginname(void) 826 { 827 char *nbuf, *p; 828 int ch; 829 830 nbuf = malloc(MAXLOGNAME); 831 if (nbuf == NULL) 832 err(1, "malloc()"); 833 do { 834 (void)printf("%s", prompt); 835 for (p = nbuf; (ch = getchar()) != '\n'; ) { 836 if (ch == EOF) { 837 badlogin(username); 838 bail(NO_SLEEP_EXIT, 0); 839 } 840 if (p < nbuf + MAXLOGNAME - 1) 841 *p++ = ch; 842 } 843 } while (p == nbuf); 844 845 *p = '\0'; 846 if (nbuf[0] == '-') { 847 pam_silent = 0; 848 memmove(nbuf, nbuf + 1, strlen(nbuf)); 849 } else { 850 pam_silent = PAM_SILENT; 851 } 852 return nbuf; 853 } 854 855 /* 856 * SIGINT handler for motd(). 857 */ 858 static volatile int motdinterrupt; 859 static void 860 sigint(int signo __unused) 861 { 862 motdinterrupt = 1; 863 } 864 865 /* 866 * Display the contents of a file (such as /etc/motd). 867 */ 868 static int 869 motd(const char *motdfile) 870 { 871 struct sigaction newint, oldint; 872 FILE *f; 873 int ch; 874 875 if ((f = fopen(motdfile, "r")) == NULL) 876 return (-1); 877 motdinterrupt = 0; 878 newint.sa_handler = sigint; 879 newint.sa_flags = 0; 880 sigfillset(&newint.sa_mask); 881 sigaction(SIGINT, &newint, &oldint); 882 while ((ch = fgetc(f)) != EOF && !motdinterrupt) 883 putchar(ch); 884 sigaction(SIGINT, &oldint, NULL); 885 if (ch != EOF || ferror(f)) { 886 fclose(f); 887 return (-1); 888 } 889 fclose(f); 890 return (0); 891 } 892 893 /* 894 * SIGALRM handler, to enforce login prompt timeout. 895 * 896 * XXX This can potentially confuse the hell out of PAM. We should 897 * XXX instead implement a conversation function that returns 898 * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal 899 * XXX handler just set a flag. 900 */ 901 static void 902 timedout(int signo __unused) 903 { 904 905 longjmp(timeout_buf, signo); 906 } 907 908 static void 909 badlogin(char *name) 910 { 911 912 if (failures == 0) 913 return; 914 if (hflag) { 915 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s", 916 failures, failures > 1 ? "S" : "", hostname); 917 syslog(LOG_AUTHPRIV|LOG_NOTICE, 918 "%d LOGIN FAILURE%s FROM %s, %s", 919 failures, failures > 1 ? "S" : "", hostname, name); 920 } else { 921 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s", 922 failures, failures > 1 ? "S" : "", tty); 923 syslog(LOG_AUTHPRIV|LOG_NOTICE, 924 "%d LOGIN FAILURE%s ON %s, %s", 925 failures, failures > 1 ? "S" : "", tty, name); 926 } 927 failures = 0; 928 } 929 930 const char * 931 stypeof(char *ttyid) 932 { 933 struct ttyent *t; 934 935 if (ttyid != NULL && *ttyid != '\0') { 936 t = getttynam(ttyid); 937 if (t != NULL && t->ty_type != NULL) 938 return (t->ty_type); 939 } 940 return (NULL); 941 } 942 943 static void 944 refused(const char *msg, const char *rtype, int lout) 945 { 946 947 if (msg != NULL) 948 printf("%s.\n", msg); 949 if (hflag) 950 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s", 951 pwd->pw_name, rtype, hostname, tty); 952 else 953 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s", 954 pwd->pw_name, rtype, tty); 955 if (lout) 956 bail(SLEEP_EXIT, 1); 957 } 958 959 /* 960 * Log a PAM error 961 */ 962 static void 963 pam_syslog(const char *msg) 964 { 965 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); 966 } 967 968 /* 969 * Shut down PAM 970 */ 971 static void 972 pam_cleanup(void) 973 { 974 975 if (pamh != NULL) { 976 if (pam_session_established) { 977 pam_err = pam_close_session(pamh, 0); 978 if (pam_err != PAM_SUCCESS) 979 pam_syslog("pam_close_session()"); 980 } 981 pam_session_established = 0; 982 if (pam_cred_established) { 983 pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED); 984 if (pam_err != PAM_SUCCESS) 985 pam_syslog("pam_setcred()"); 986 } 987 pam_cred_established = 0; 988 pam_end(pamh, pam_err); 989 pamh = NULL; 990 } 991 } 992 993 static void 994 bail_internal(int sec, int eval, int signo) 995 { 996 struct sigaction sa; 997 998 pam_cleanup(); 999 #ifdef USE_BSM_AUDIT 1000 if (pwd != NULL) 1001 audit_logout(); 1002 #endif 1003 (void)sleep(sec); 1004 if (signo == 0) 1005 exit(eval); 1006 else { 1007 sa.sa_handler = SIG_DFL; 1008 sa.sa_flags = 0; 1009 (void)sigemptyset(&sa.sa_mask); 1010 (void)sigaction(signo, &sa, NULL); 1011 (void)sigaddset(&sa.sa_mask, signo); 1012 (void)sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL); 1013 raise(signo); 1014 exit(128 + signo); 1015 } 1016 } 1017 1018 /* 1019 * Exit, optionally after sleeping a few seconds 1020 */ 1021 static void 1022 bail(int sec, int eval) 1023 { 1024 bail_internal(sec, eval, 0); 1025 } 1026 1027 /* 1028 * Exit because of a signal. 1029 * This is not async-signal safe, so only call async-signal safe functions 1030 * while the signal is unmasked. 1031 */ 1032 static void 1033 bail_sig(int signo) 1034 { 1035 bail_internal(NO_SLEEP_EXIT, 0, signo); 1036 } 1037