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 struct passwd *pwd; 114 static int failures; 115 116 static char *envinit[1]; /* empty environment list */ 117 118 /* 119 * Command line flags and arguments 120 */ 121 static int fflag; /* -f: do not perform authentication */ 122 static int hflag; /* -h: login from remote host */ 123 static char *hostname; /* hostname from command line */ 124 static int pflag; /* -p: preserve environment */ 125 126 /* 127 * User name 128 */ 129 static char *username; /* user name */ 130 static char *olduser; /* previous user name */ 131 132 /* 133 * Prompts 134 */ 135 static char default_prompt[] = DEFAULT_PROMPT; 136 static const char *prompt; 137 static char default_passwd_prompt[] = DEFAULT_PASSWD_PROMPT; 138 static const char *passwd_prompt; 139 140 static char *tty; 141 142 /* 143 * PAM data 144 */ 145 static pam_handle_t *pamh = NULL; 146 static struct pam_conv pamc = { openpam_ttyconv, NULL }; 147 static int pam_err; 148 static int pam_silent = PAM_SILENT; 149 static int pam_cred_established; 150 static int pam_session_established; 151 152 int 153 main(int argc, char *argv[]) 154 { 155 struct group *gr; 156 struct stat st; 157 int retries, backoff; 158 int ask, ch, cnt, quietlog, rootlogin, rval; 159 uid_t uid, euid; 160 gid_t egid; 161 char *term; 162 char *p, *ttyn; 163 char tname[sizeof(_PATH_TTY) + 10]; 164 char *arg0; 165 const char *tp; 166 const char *shell = NULL; 167 login_cap_t *lc = NULL; 168 login_cap_t *lc_user = NULL; 169 pid_t pid; 170 sigset_t mask, omask; 171 struct sigaction sa; 172 #ifdef USE_BSM_AUDIT 173 char auditsuccess = 1; 174 #endif 175 176 sa.sa_flags = SA_RESTART; 177 (void)sigfillset(&sa.sa_mask); 178 sa.sa_handler = SIG_IGN; 179 (void)sigaction(SIGQUIT, &sa, NULL); 180 (void)sigaction(SIGINT, &sa, NULL); 181 (void)sigaction(SIGHUP, &sa, NULL); 182 if (setjmp(timeout_buf)) { 183 if (failures) 184 badlogin(username); 185 (void)fprintf(stderr, "Login timed out after %d seconds\n", 186 timeout); 187 bail(NO_SLEEP_EXIT, 0); 188 } 189 sa.sa_handler = timedout; 190 (void)sigaction(SIGALRM, &sa, NULL); 191 (void)alarm(timeout); 192 (void)setpriority(PRIO_PROCESS, 0, 0); 193 194 openlog("login", LOG_CONS, LOG_AUTH); 195 196 uid = getuid(); 197 euid = geteuid(); 198 egid = getegid(); 199 200 while ((ch = getopt(argc, argv, "fh:p")) != -1) 201 switch (ch) { 202 case 'f': 203 fflag = 1; 204 break; 205 case 'h': 206 if (uid != 0) 207 errx(1, "-h option: %s", strerror(EPERM)); 208 if (strlen(optarg) >= MAXHOSTNAMELEN) 209 errx(1, "-h option: %s: exceeds maximum " 210 "hostname size", optarg); 211 hflag = 1; 212 hostname = optarg; 213 break; 214 case 'p': 215 pflag = 1; 216 break; 217 case '?': 218 default: 219 if (uid == 0) 220 syslog(LOG_ERR, "invalid flag %c", ch); 221 usage(); 222 } 223 argc -= optind; 224 argv += optind; 225 226 if (argc > 0) { 227 username = strdup(*argv); 228 if (username == NULL) 229 err(1, "strdup()"); 230 ask = 0; 231 } else { 232 ask = 1; 233 } 234 235 setproctitle("-%s", getprogname()); 236 237 closefrom(3); 238 239 /* 240 * Get current TTY 241 */ 242 ttyn = ttyname(STDIN_FILENO); 243 if (ttyn == NULL || *ttyn == '\0') { 244 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY); 245 ttyn = tname; 246 } 247 if (strncmp(ttyn, _PATH_DEV, sizeof _PATH_DEV - 1) == 0) 248 tty = ttyn + sizeof _PATH_DEV - 1; 249 else 250 tty = ttyn; 251 252 /* 253 * Get "login-retries" & "login-backoff" from default class 254 */ 255 lc = login_getclass(NULL); 256 prompt = login_getcapstr(lc, "login_prompt", 257 default_prompt, default_prompt); 258 passwd_prompt = login_getcapstr(lc, "passwd_prompt", 259 default_passwd_prompt, default_passwd_prompt); 260 retries = login_getcapnum(lc, "login-retries", 261 DEFAULT_RETRIES, DEFAULT_RETRIES); 262 backoff = login_getcapnum(lc, "login-backoff", 263 DEFAULT_BACKOFF, DEFAULT_BACKOFF); 264 login_close(lc); 265 lc = NULL; 266 267 /* 268 * Try to authenticate the user until we succeed or time out. 269 */ 270 for (cnt = 0;; ask = 1) { 271 if (ask) { 272 fflag = 0; 273 if (olduser != NULL) 274 free(olduser); 275 olduser = username; 276 username = getloginname(); 277 } 278 rootlogin = 0; 279 280 /* 281 * Note if trying multiple user names; log failures for 282 * previous user name, but don't bother logging one failure 283 * for nonexistent name (mistyped username). 284 */ 285 if (failures && strcmp(olduser, username) != 0) { 286 if (failures > (pwd ? 0 : 1)) 287 badlogin(olduser); 288 } 289 290 /* 291 * Load the PAM policy and set some variables 292 */ 293 pam_err = pam_start("login", username, &pamc, &pamh); 294 if (pam_err != PAM_SUCCESS) { 295 pam_syslog("pam_start()"); 296 #ifdef USE_BSM_AUDIT 297 au_login_fail("PAM Error", 1); 298 #endif 299 bail(NO_SLEEP_EXIT, 1); 300 } 301 pam_err = pam_set_item(pamh, PAM_TTY, tty); 302 if (pam_err != PAM_SUCCESS) { 303 pam_syslog("pam_set_item(PAM_TTY)"); 304 #ifdef USE_BSM_AUDIT 305 au_login_fail("PAM Error", 1); 306 #endif 307 bail(NO_SLEEP_EXIT, 1); 308 } 309 pam_err = pam_set_item(pamh, PAM_RHOST, hostname); 310 if (pam_err != PAM_SUCCESS) { 311 pam_syslog("pam_set_item(PAM_RHOST)"); 312 #ifdef USE_BSM_AUDIT 313 au_login_fail("PAM Error", 1); 314 #endif 315 bail(NO_SLEEP_EXIT, 1); 316 } 317 318 pwd = getpwnam(username); 319 if (pwd != NULL && pwd->pw_uid == 0) 320 rootlogin = 1; 321 322 /* 323 * If the -f option was specified and the caller is 324 * root or the caller isn't changing their uid, don't 325 * authenticate. 326 */ 327 if (pwd != NULL && fflag && 328 (uid == (uid_t)0 || uid == (uid_t)pwd->pw_uid)) { 329 /* already authenticated */ 330 rval = 0; 331 #ifdef USE_BSM_AUDIT 332 auditsuccess = 0; /* opened a terminal window only */ 333 #endif 334 } else { 335 fflag = 0; 336 (void)setpriority(PRIO_PROCESS, 0, -4); 337 rval = auth_pam(); 338 (void)setpriority(PRIO_PROCESS, 0, 0); 339 } 340 341 if (pwd && rval == 0) 342 break; 343 344 pam_cleanup(); 345 346 /* 347 * We are not exiting here, but this corresponds to a failed 348 * login event, so set exitstatus to 1. 349 */ 350 #ifdef USE_BSM_AUDIT 351 au_login_fail("Login incorrect", 1); 352 #endif 353 354 (void)printf("Login incorrect\n"); 355 failures++; 356 357 pwd = NULL; 358 359 /* 360 * Allow up to 'retry' (10) attempts, but start 361 * backing off after 'backoff' (3) attempts. 362 */ 363 if (++cnt > backoff) { 364 if (cnt >= retries) { 365 badlogin(username); 366 bail(SLEEP_EXIT, 1); 367 } 368 sleep((u_int)((cnt - backoff) * 5)); 369 } 370 } 371 372 /* committed to login -- turn off timeout */ 373 (void)alarm((u_int)0); 374 375 (void)sigemptyset(&mask); 376 (void)sigaddset(&mask, SIGHUP); 377 (void)sigaddset(&mask, SIGTERM); 378 (void)sigprocmask(SIG_BLOCK, &mask, &omask); 379 sa.sa_handler = bail_sig; 380 (void)sigaction(SIGHUP, &sa, NULL); 381 (void)sigaction(SIGTERM, &sa, NULL); 382 383 endpwent(); 384 385 #ifdef USE_BSM_AUDIT 386 /* Audit successful login. */ 387 if (auditsuccess) 388 au_login_success(); 389 #endif 390 391 /* 392 * This needs to happen before login_getpwclass to support 393 * home directories on GSS-API authenticated NFS where the 394 * kerberos credentials need to be saved so that the kernel 395 * can authenticate to the NFS server. 396 */ 397 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); 398 if (pam_err != PAM_SUCCESS) { 399 pam_syslog("pam_setcred()"); 400 bail(NO_SLEEP_EXIT, 1); 401 } 402 pam_cred_established = 1; 403 404 /* 405 * Establish the login class. 406 */ 407 lc = login_getpwclass(pwd); 408 lc_user = login_getuserclass(pwd); 409 410 if (!(quietlog = login_getcapbool(lc_user, "hushlogin", 0))) 411 quietlog = login_getcapbool(lc, "hushlogin", 0); 412 413 /* 414 * Switching needed for NFS with root access disabled. 415 * 416 * XXX: This change fails to modify the additional groups for the 417 * process, and as such, may restrict rights normally granted 418 * through those groups. 419 */ 420 (void)setegid(pwd->pw_gid); 421 (void)seteuid(rootlogin ? 0 : pwd->pw_uid); 422 if (!*pwd->pw_dir || chdir(pwd->pw_dir) < 0) { 423 if (login_getcapbool(lc, "requirehome", 0)) 424 refused("Home directory not available", "HOMEDIR", 1); 425 if (chdir("/") < 0) 426 refused("Cannot find root directory", "ROOTDIR", 1); 427 if (!quietlog || *pwd->pw_dir) 428 printf("No home directory.\nLogging in with home = \"/\".\n"); 429 pwd->pw_dir = strdup("/"); 430 if (pwd->pw_dir == NULL) { 431 syslog(LOG_NOTICE, "strdup(): %m"); 432 bail(SLEEP_EXIT, 1); 433 } 434 } 435 (void)seteuid(euid); 436 (void)setegid(egid); 437 if (!quietlog) { 438 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; 439 if (!quietlog) 440 pam_silent = 0; 441 } 442 443 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); 444 if (*pwd->pw_shell == '\0') 445 pwd->pw_shell = strdup(_PATH_BSHELL); 446 if (pwd->pw_shell == NULL) { 447 syslog(LOG_NOTICE, "strdup(): %m"); 448 bail(SLEEP_EXIT, 1); 449 } 450 if (*shell == '\0') /* Not overridden */ 451 shell = pwd->pw_shell; 452 if ((shell = strdup(shell)) == NULL) { 453 syslog(LOG_NOTICE, "strdup(): %m"); 454 bail(SLEEP_EXIT, 1); 455 } 456 457 /* 458 * Set device protections, depending on what terminal the 459 * user is logged in. This feature is used on Suns to give 460 * console users better privacy. 461 */ 462 login_fbtab(tty, pwd->pw_uid, pwd->pw_gid); 463 464 /* 465 * Clear flags of the tty. None should be set, and when the 466 * user sets them otherwise, this can cause the chown to fail. 467 * Since it isn't clear that flags are useful on character 468 * devices, we just clear them. 469 * 470 * We don't log in the case of EOPNOTSUPP because dev might be 471 * on NFS, which doesn't support chflags. 472 * 473 * We don't log in the EROFS because that means that /dev is on 474 * a read only file system and we assume that the permissions there 475 * are sane. 476 */ 477 if (ttyn != tname && chflags(ttyn, 0)) 478 if (errno != EOPNOTSUPP && errno != EROFS) 479 syslog(LOG_ERR, "chflags(%s): %m", ttyn); 480 if (ttyn != tname && chown(ttyn, pwd->pw_uid, 481 (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid)) 482 if (errno != EROFS) 483 syslog(LOG_ERR, "chown(%s): %m", ttyn); 484 485 #ifdef LOGALL 486 /* 487 * Syslog each successful login, so we don't have to watch 488 * hundreds of wtmp or lastlogin files. 489 */ 490 if (hflag) 491 syslog(LOG_INFO, "login from %s on %s as %s", 492 hostname, tty, pwd->pw_name); 493 else 494 syslog(LOG_INFO, "login on %s as %s", 495 tty, pwd->pw_name); 496 #endif 497 498 /* 499 * If fflag is on, assume caller/authenticator has logged root 500 * login. 501 */ 502 if (rootlogin && fflag == 0) { 503 if (hflag) 504 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s FROM %s", 505 username, tty, hostname); 506 else 507 syslog(LOG_NOTICE, "ROOT LOGIN (%s) ON %s", 508 username, tty); 509 } 510 511 /* 512 * Destroy environment unless user has requested its 513 * preservation - but preserve TERM in all cases 514 */ 515 term = getenv("TERM"); 516 if (!pflag) 517 environ = envinit; 518 if (term != NULL) 519 setenv("TERM", term, 0); 520 521 /* 522 * PAM modules might add supplementary groups during pam_setcred(). 523 */ 524 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { 525 syslog(LOG_ERR, "setusercontext() failed - exiting"); 526 bail(NO_SLEEP_EXIT, 1); 527 } 528 529 pam_err = pam_setcred(pamh, pam_silent|PAM_REINITIALIZE_CRED); 530 if (pam_err != PAM_SUCCESS) { 531 pam_syslog("pam_setcred()"); 532 bail(NO_SLEEP_EXIT, 1); 533 } 534 535 pam_err = pam_open_session(pamh, pam_silent); 536 if (pam_err != PAM_SUCCESS) { 537 pam_syslog("pam_open_session()"); 538 bail(NO_SLEEP_EXIT, 1); 539 } 540 pam_session_established = 1; 541 542 /* 543 * We must fork() before setuid() because we need to call 544 * pam_close_session() as root. 545 */ 546 pid = fork(); 547 if (pid < 0) { 548 err(1, "fork"); 549 } else if (pid != 0) { 550 /* 551 * Parent: wait for child to finish, then clean up 552 * session. 553 * 554 * If we get SIGHUP or SIGTERM, clean up the session 555 * and exit right away. This will make the terminal 556 * inaccessible and send SIGHUP to the foreground 557 * process group. 558 */ 559 int status; 560 setproctitle("-%s [pam]", getprogname()); 561 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 562 waitpid(pid, &status, 0); 563 (void)sigprocmask(SIG_BLOCK, &mask, NULL); 564 bail(NO_SLEEP_EXIT, 0); 565 } 566 567 /* 568 * NOTICE: We are now in the child process! 569 */ 570 571 /* 572 * Add any environment variables the PAM modules may have set. 573 */ 574 export_pam_environment(); 575 576 /* 577 * We're done with PAM now; our parent will deal with the rest. 578 */ 579 pam_end(pamh, 0); 580 pamh = NULL; 581 582 /* 583 * We don't need to be root anymore, so set the login name and 584 * the UID. 585 */ 586 if (setlogin(username) != 0) { 587 syslog(LOG_ERR, "setlogin(%s): %m - exiting", username); 588 bail(NO_SLEEP_EXIT, 1); 589 } 590 if (setusercontext(lc, pwd, pwd->pw_uid, 591 LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETGROUP)) != 0) { 592 syslog(LOG_ERR, "setusercontext() failed - exiting"); 593 exit(1); 594 } 595 596 (void)setenv("SHELL", pwd->pw_shell, 1); 597 (void)setenv("HOME", pwd->pw_dir, 1); 598 /* Overwrite "term" from login.conf(5) for any known TERM */ 599 if (term == NULL && (tp = stypeof(tty)) != NULL) 600 (void)setenv("TERM", tp, 1); 601 else 602 (void)setenv("TERM", TERM_UNKNOWN, 0); 603 (void)setenv("LOGNAME", username, 1); 604 (void)setenv("USER", username, 1); 605 (void)setenv("PATH", rootlogin ? _PATH_STDPATH : _PATH_DEFPATH, 0); 606 607 if (!quietlog) { 608 const char *cw; 609 610 cw = login_getcapstr(lc, "welcome", NULL, NULL); 611 if (cw != NULL && access(cw, F_OK) == 0) 612 motd(cw); 613 else 614 motd(_PATH_MOTDFILE); 615 616 if (login_getcapbool(lc_user, "nocheckmail", 0) == 0 && 617 login_getcapbool(lc, "nocheckmail", 0) == 0) { 618 char *cx; 619 620 /* $MAIL may have been set by class. */ 621 cx = getenv("MAIL"); 622 if (cx == NULL) { 623 asprintf(&cx, "%s/%s", 624 _PATH_MAILDIR, pwd->pw_name); 625 } 626 if (cx && stat(cx, &st) == 0 && st.st_size != 0) 627 (void)printf("You have %smail.\n", 628 (st.st_mtime > st.st_atime) ? "new " : ""); 629 if (getenv("MAIL") == NULL) 630 free(cx); 631 } 632 } 633 634 login_close(lc_user); 635 login_close(lc); 636 637 sa.sa_handler = SIG_DFL; 638 (void)sigaction(SIGALRM, &sa, NULL); 639 (void)sigaction(SIGQUIT, &sa, NULL); 640 (void)sigaction(SIGINT, &sa, NULL); 641 (void)sigaction(SIGTERM, &sa, NULL); 642 (void)sigaction(SIGHUP, &sa, NULL); 643 sa.sa_handler = SIG_IGN; 644 (void)sigaction(SIGTSTP, &sa, NULL); 645 (void)sigprocmask(SIG_SETMASK, &omask, NULL); 646 647 /* 648 * Login shells have a leading '-' in front of argv[0] 649 */ 650 p = strrchr(pwd->pw_shell, '/'); 651 if (asprintf(&arg0, "-%s", p ? p + 1 : pwd->pw_shell) >= MAXPATHLEN) { 652 syslog(LOG_ERR, "user: %s: shell exceeds maximum pathname size", 653 username); 654 errx(1, "shell exceeds maximum pathname size"); 655 } else if (arg0 == NULL) { 656 err(1, "asprintf()"); 657 } 658 659 execlp(shell, arg0, (char *)0); 660 err(1, "%s", shell); 661 662 /* 663 * That's it, folks! 664 */ 665 } 666 667 /* 668 * Attempt to authenticate the user using PAM. Returns 0 if the user is 669 * authenticated, or 1 if not authenticated. If some sort of PAM system 670 * error occurs (e.g., the "/etc/pam.conf" file is missing) then this 671 * function returns -1. This can be used as an indication that we should 672 * fall back to a different authentication mechanism. 673 */ 674 static int 675 auth_pam(void) 676 { 677 const char *tmpl_user; 678 const void *item; 679 int rval; 680 681 pam_err = pam_authenticate(pamh, pam_silent); 682 switch (pam_err) { 683 684 case PAM_SUCCESS: 685 /* 686 * With PAM we support the concept of a "template" 687 * user. The user enters a login name which is 688 * authenticated by PAM, usually via a remote service 689 * such as RADIUS or TACACS+. If authentication 690 * succeeds, a different but related "template" name 691 * is used for setting the credentials, shell, and 692 * home directory. The name the user enters need only 693 * exist on the remote authentication server, but the 694 * template name must be present in the local password 695 * database. 696 * 697 * This is supported by two various mechanisms in the 698 * individual modules. However, from the application's 699 * point of view, the template user is always passed 700 * back as a changed value of the PAM_USER item. 701 */ 702 pam_err = pam_get_item(pamh, PAM_USER, &item); 703 if (pam_err == PAM_SUCCESS) { 704 tmpl_user = (const char *)item; 705 if (strcmp(username, tmpl_user) != 0) 706 pwd = getpwnam(tmpl_user); 707 } else { 708 pam_syslog("pam_get_item(PAM_USER)"); 709 } 710 rval = 0; 711 break; 712 713 case PAM_AUTH_ERR: 714 case PAM_USER_UNKNOWN: 715 case PAM_MAXTRIES: 716 rval = 1; 717 break; 718 719 default: 720 pam_syslog("pam_authenticate()"); 721 rval = -1; 722 break; 723 } 724 725 if (rval == 0) { 726 pam_err = pam_acct_mgmt(pamh, pam_silent); 727 switch (pam_err) { 728 case PAM_SUCCESS: 729 break; 730 case PAM_NEW_AUTHTOK_REQD: 731 pam_err = pam_chauthtok(pamh, 732 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); 733 if (pam_err != PAM_SUCCESS) { 734 pam_syslog("pam_chauthtok()"); 735 rval = 1; 736 } 737 break; 738 default: 739 pam_syslog("pam_acct_mgmt()"); 740 rval = 1; 741 break; 742 } 743 } 744 745 if (rval != 0) { 746 pam_end(pamh, pam_err); 747 pamh = NULL; 748 } 749 return (rval); 750 } 751 752 /* 753 * Export any environment variables PAM modules may have set 754 */ 755 static void 756 export_pam_environment(void) 757 { 758 char **pam_env; 759 char **pp; 760 761 pam_env = pam_getenvlist(pamh); 762 if (pam_env != NULL) { 763 for (pp = pam_env; *pp != NULL; pp++) { 764 (void)export(*pp); 765 free(*pp); 766 } 767 } 768 } 769 770 /* 771 * Perform sanity checks on an environment variable: 772 * - Make sure there is an '=' in the string. 773 * - Make sure the string doesn't run on too long. 774 * - Do not export certain variables. This list was taken from the 775 * Solaris pam_putenv(3) man page. 776 * Then export it. 777 */ 778 static int 779 export(const char *s) 780 { 781 static const char *noexport[] = { 782 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH", 783 "IFS", "PATH", NULL 784 }; 785 char *p; 786 const char **pp; 787 size_t n; 788 int rv; 789 790 if (strlen(s) > 1024 || (p = strchr(s, '=')) == NULL) 791 return (0); 792 if (strncmp(s, "LD_", 3) == 0) 793 return (0); 794 for (pp = noexport; *pp != NULL; pp++) { 795 n = strlen(*pp); 796 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 797 return (0); 798 } 799 *p = '\0'; 800 rv = setenv(s, p + 1, 1); 801 *p = '='; 802 if (rv == -1) 803 return (0); 804 return (1); 805 } 806 807 static void 808 usage(void) 809 { 810 811 (void)fprintf(stderr, "usage: login [-fp] [-h hostname] [username]\n"); 812 exit(1); 813 } 814 815 /* 816 * Prompt user and read login name from stdin. 817 */ 818 static char * 819 getloginname(void) 820 { 821 char *nbuf, *p; 822 int ch; 823 824 nbuf = malloc(MAXLOGNAME); 825 if (nbuf == NULL) 826 err(1, "malloc()"); 827 do { 828 (void)printf("%s", prompt); 829 for (p = nbuf; (ch = getchar()) != '\n'; ) { 830 if (ch == EOF) { 831 badlogin(username); 832 bail(NO_SLEEP_EXIT, 0); 833 } 834 if (p < nbuf + MAXLOGNAME - 1) 835 *p++ = ch; 836 } 837 } while (p == nbuf); 838 839 *p = '\0'; 840 if (nbuf[0] == '-') { 841 pam_silent = 0; 842 memmove(nbuf, nbuf + 1, strlen(nbuf)); 843 } else { 844 pam_silent = PAM_SILENT; 845 } 846 return nbuf; 847 } 848 849 /* 850 * SIGINT handler for motd(). 851 */ 852 static volatile int motdinterrupt; 853 static void 854 sigint(int signo __unused) 855 { 856 motdinterrupt = 1; 857 } 858 859 /* 860 * Display the contents of a file (such as /etc/motd). 861 */ 862 static int 863 motd(const char *motdfile) 864 { 865 struct sigaction newint, oldint; 866 FILE *f; 867 int ch; 868 869 if ((f = fopen(motdfile, "r")) == NULL) 870 return (-1); 871 motdinterrupt = 0; 872 newint.sa_handler = sigint; 873 newint.sa_flags = 0; 874 sigfillset(&newint.sa_mask); 875 sigaction(SIGINT, &newint, &oldint); 876 while ((ch = fgetc(f)) != EOF && !motdinterrupt) 877 putchar(ch); 878 sigaction(SIGINT, &oldint, NULL); 879 if (ch != EOF || ferror(f)) { 880 fclose(f); 881 return (-1); 882 } 883 fclose(f); 884 return (0); 885 } 886 887 /* 888 * SIGALRM handler, to enforce login prompt timeout. 889 * 890 * XXX This can potentially confuse the hell out of PAM. We should 891 * XXX instead implement a conversation function that returns 892 * XXX PAM_CONV_ERR when interrupted by a signal, and have the signal 893 * XXX handler just set a flag. 894 */ 895 static void 896 timedout(int signo __unused) 897 { 898 899 longjmp(timeout_buf, signo); 900 } 901 902 static void 903 badlogin(char *name) 904 { 905 906 if (failures == 0) 907 return; 908 if (hflag) { 909 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s FROM %s", 910 failures, failures > 1 ? "S" : "", hostname); 911 syslog(LOG_AUTHPRIV|LOG_NOTICE, 912 "%d LOGIN FAILURE%s FROM %s, %s", 913 failures, failures > 1 ? "S" : "", hostname, name); 914 } else { 915 syslog(LOG_NOTICE, "%d LOGIN FAILURE%s ON %s", 916 failures, failures > 1 ? "S" : "", tty); 917 syslog(LOG_AUTHPRIV|LOG_NOTICE, 918 "%d LOGIN FAILURE%s ON %s, %s", 919 failures, failures > 1 ? "S" : "", tty, name); 920 } 921 failures = 0; 922 } 923 924 const char * 925 stypeof(char *ttyid) 926 { 927 struct ttyent *t; 928 929 if (ttyid != NULL && *ttyid != '\0') { 930 t = getttynam(ttyid); 931 if (t != NULL && t->ty_type != NULL) 932 return (t->ty_type); 933 } 934 return (NULL); 935 } 936 937 static void 938 refused(const char *msg, const char *rtype, int lout) 939 { 940 941 if (msg != NULL) 942 printf("%s.\n", msg); 943 if (hflag) 944 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) FROM %s ON TTY %s", 945 pwd->pw_name, rtype, hostname, tty); 946 else 947 syslog(LOG_NOTICE, "LOGIN %s REFUSED (%s) ON TTY %s", 948 pwd->pw_name, rtype, tty); 949 if (lout) 950 bail(SLEEP_EXIT, 1); 951 } 952 953 /* 954 * Log a PAM error 955 */ 956 static void 957 pam_syslog(const char *msg) 958 { 959 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); 960 } 961 962 /* 963 * Shut down PAM 964 */ 965 static void 966 pam_cleanup(void) 967 { 968 969 if (pamh != NULL) { 970 if (pam_session_established) { 971 pam_err = pam_close_session(pamh, 0); 972 if (pam_err != PAM_SUCCESS) 973 pam_syslog("pam_close_session()"); 974 } 975 pam_session_established = 0; 976 if (pam_cred_established) { 977 pam_err = pam_setcred(pamh, pam_silent|PAM_DELETE_CRED); 978 if (pam_err != PAM_SUCCESS) 979 pam_syslog("pam_setcred()"); 980 } 981 pam_cred_established = 0; 982 pam_end(pamh, pam_err); 983 pamh = NULL; 984 } 985 } 986 987 static void 988 bail_internal(int sec, int eval, int signo) 989 { 990 struct sigaction sa; 991 992 pam_cleanup(); 993 #ifdef USE_BSM_AUDIT 994 if (pwd != NULL) 995 audit_logout(); 996 #endif 997 (void)sleep(sec); 998 if (signo == 0) 999 exit(eval); 1000 else { 1001 sa.sa_handler = SIG_DFL; 1002 sa.sa_flags = 0; 1003 (void)sigemptyset(&sa.sa_mask); 1004 (void)sigaction(signo, &sa, NULL); 1005 (void)sigaddset(&sa.sa_mask, signo); 1006 (void)sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL); 1007 raise(signo); 1008 exit(128 + signo); 1009 } 1010 } 1011 1012 /* 1013 * Exit, optionally after sleeping a few seconds 1014 */ 1015 static void 1016 bail(int sec, int eval) 1017 { 1018 bail_internal(sec, eval, 0); 1019 } 1020 1021 /* 1022 * Exit because of a signal. 1023 * This is not async-signal safe, so only call async-signal safe functions 1024 * while the signal is unmasked. 1025 */ 1026 static void 1027 bail_sig(int signo) 1028 { 1029 bail_internal(NO_SLEEP_EXIT, 0, signo); 1030 } 1031