login_pam.c revision 1.20
1 /* $NetBSD: login_pam.c,v 1.20 2009/12/29 19:26:13 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1988, 1991, 1993, 1994\ 35 The Regents of the University of California. All rights reserved."); 36 #endif /* not lint */ 37 38 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)login.c 8.4 (Berkeley) 4/2/94"; 41 #endif 42 __RCSID("$NetBSD: login_pam.c,v 1.20 2009/12/29 19:26:13 christos Exp $"); 43 #endif /* not lint */ 44 45 /* 46 * login [ name ] 47 * login -h hostname (for telnetd, etc.) 48 * login -f name (for pre-authenticated login: datakit, xterm, etc.) 49 */ 50 51 #include <sys/param.h> 52 #include <sys/stat.h> 53 #include <sys/time.h> 54 #include <sys/resource.h> 55 #include <sys/file.h> 56 #include <sys/wait.h> 57 #include <sys/socket.h> 58 59 #include <err.h> 60 #include <errno.h> 61 #include <grp.h> 62 #include <pwd.h> 63 #include <setjmp.h> 64 #include <signal.h> 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <string.h> 68 #include <syslog.h> 69 #include <time.h> 70 #include <ttyent.h> 71 #include <tzfile.h> 72 #include <unistd.h> 73 #include <util.h> 74 #include <login_cap.h> 75 #include <vis.h> 76 77 #include <security/pam_appl.h> 78 #include <security/openpam.h> 79 80 #include "pathnames.h" 81 #include "common.h" 82 83 #if 0 84 static int rootterm(char *); 85 #endif 86 static void usage(void) __attribute__((__noreturn__)); 87 88 static struct pam_conv pamc = { openpam_ttyconv, NULL }; 89 90 #define TTYGRPNAME "tty" /* name of group to own ttys */ 91 92 #define DEFAULT_BACKOFF 3 93 #define DEFAULT_RETRIES 10 94 95 static struct passwd pwres; 96 static char pwbuf[1024]; 97 static struct group grs, *grp; 98 static char grbuf[1024]; 99 extern char **environ; 100 101 int 102 main(int argc, char *argv[]) 103 { 104 struct stat st; 105 int ask, ch, cnt, fflag, pflag, quietlog, rootlogin; 106 int auth_passed; 107 uid_t uid, saved_uid; 108 gid_t saved_gid, saved_gids[NGROUPS_MAX]; 109 int nsaved_gids; 110 char *domain, *p, *ttyn, *pwprompt; 111 char tbuf[MAXPATHLEN + 2], tname[sizeof(_PATH_TTY) + 10]; 112 char localhost[MAXHOSTNAMELEN + 1]; 113 int need_chpass, require_chpass; 114 int login_retries = DEFAULT_RETRIES, 115 login_backoff = DEFAULT_BACKOFF; 116 char *shell = NULL; 117 login_cap_t *lc = NULL; 118 pam_handle_t *pamh = NULL; 119 int pam_err; 120 sig_t oint, oabrt, oquit, oalrm; 121 const void *newuser; 122 int pam_silent = PAM_SILENT; 123 pid_t xpid, pid; 124 int status; 125 char *saved_term; 126 char **pamenv; 127 128 tbuf[0] = '\0'; 129 pwprompt = NULL; 130 nested = NULL; 131 need_chpass = require_chpass = 0; 132 133 oabrt = signal(SIGABRT, SIG_IGN); 134 oalrm = signal(SIGALRM, timedout); 135 oint = signal(SIGINT, SIG_IGN); 136 oquit = signal(SIGQUIT, SIG_IGN); 137 138 (void)alarm(timeout); 139 (void)setpriority(PRIO_PROCESS, 0, 0); 140 141 openlog("login", 0, LOG_AUTH); 142 143 /* 144 * -p is used by getty to tell login not to destroy the environment 145 * -f is used to skip a second login authentication 146 * -h is used by other servers to pass the name of the remote host to 147 * login so that it may be placed in utmp/utmpx and wtmp/wtmpx 148 * -a in addition to -h, a server my supply -a to pass the actual 149 * server address. 150 */ 151 domain = NULL; 152 if (gethostname(localhost, sizeof(localhost)) < 0) 153 syslog(LOG_ERR, "couldn't get local hostname: %m"); 154 else 155 domain = strchr(localhost, '.'); 156 localhost[sizeof(localhost) - 1] = '\0'; 157 158 fflag = pflag = 0; 159 have_ss = 0; 160 uid = getuid(); 161 while ((ch = getopt(argc, argv, "a:fh:p")) != -1) 162 switch (ch) { 163 case 'a': 164 if (uid) { 165 errno = EPERM; 166 err(EXIT_FAILURE, "-a option"); 167 } 168 decode_ss(optarg); 169 break; 170 case 'f': 171 fflag = 1; 172 break; 173 case 'h': 174 if (uid) { 175 errno = EPERM; 176 err(EXIT_FAILURE, "-h option"); 177 } 178 if (domain && (p = strchr(optarg, '.')) != NULL && 179 strcasecmp(p, domain) == 0) 180 *p = '\0'; 181 hostname = optarg; 182 break; 183 case 'p': 184 pflag = 1; 185 break; 186 default: 187 case '?': 188 usage(); 189 break; 190 } 191 192 setproctitle(NULL); 193 argc -= optind; 194 argv += optind; 195 196 if (*argv) { 197 username = *argv; 198 ask = 0; 199 } else 200 ask = 1; 201 202 #ifdef F_CLOSEM 203 (void)fcntl(3, F_CLOSEM, 0); 204 #else 205 for (cnt = getdtablesize(); cnt > 2; cnt--) 206 (void)close(cnt); 207 #endif 208 209 ttyn = ttyname(STDIN_FILENO); 210 if (ttyn == NULL || *ttyn == '\0') { 211 (void)snprintf(tname, sizeof(tname), "%s??", _PATH_TTY); 212 ttyn = tname; 213 } 214 if ((tty = strstr(ttyn, "/pts/")) != NULL) 215 ++tty; 216 else if ((tty = strrchr(ttyn, '/')) != NULL) 217 ++tty; 218 else 219 tty = ttyn; 220 221 if (issetugid()) { 222 nested = strdup(user_from_uid(getuid(), 0)); 223 if (nested == NULL) { 224 syslog(LOG_ERR, "strdup: %m"); 225 sleepexit(EXIT_FAILURE); 226 } 227 } 228 229 /* Get "login-retries" and "login-backoff" from default class */ 230 if ((lc = login_getclass(NULL)) != NULL) { 231 login_retries = (int)login_getcapnum(lc, "login-retries", 232 DEFAULT_RETRIES, DEFAULT_RETRIES); 233 login_backoff = (int)login_getcapnum(lc, "login-backoff", 234 DEFAULT_BACKOFF, DEFAULT_BACKOFF); 235 login_close(lc); 236 lc = NULL; 237 } 238 239 240 for (cnt = 0;; ask = 1) { 241 if (ask) { 242 fflag = 0; 243 getloginname(); 244 } 245 rootlogin = 0; 246 auth_passed = 0; 247 if (strlen(username) > MAXLOGNAME) 248 username[MAXLOGNAME] = '\0'; 249 250 /* 251 * Note if trying multiple user names; log failures for 252 * previous user name, but don't bother logging one failure 253 * for nonexistent name (mistyped username). 254 */ 255 if (failures && strcmp(tbuf, username)) { 256 if (failures > (pwd ? 0 : 1)) 257 badlogin(tbuf); 258 failures = 0; 259 } 260 261 #define PAM_END(msg) do { \ 262 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); \ 263 warnx("%s: %s", msg, pam_strerror(pamh, pam_err)); \ 264 pam_end(pamh, pam_err); \ 265 sleepexit(EXIT_FAILURE); \ 266 } while (/*CONSTCOND*/0) 267 268 pam_err = pam_start("login", username, &pamc, &pamh); 269 if (pam_err != PAM_SUCCESS) { 270 if (pamh != NULL) 271 PAM_END("pam_start"); 272 /* Things went really bad... */ 273 syslog(LOG_ERR, "pam_start failed: %s", 274 pam_strerror(pamh, pam_err)); 275 errx(EXIT_FAILURE, "pam_start failed"); 276 } 277 278 #define PAM_SET_ITEM(item, var) do { \ 279 pam_err = pam_set_item(pamh, (item), (var)); \ 280 if (pam_err != PAM_SUCCESS) \ 281 PAM_END("pam_set_item(" # item ")"); \ 282 } while (/*CONSTCOND*/0) 283 284 /* 285 * Fill hostname tty, and nested user 286 */ 287 PAM_SET_ITEM(PAM_RHOST, hostname); 288 PAM_SET_ITEM(PAM_TTY, tty); 289 if (nested) 290 PAM_SET_ITEM(PAM_NUSER, nested); 291 if (have_ss) 292 PAM_SET_ITEM(PAM_SOCKADDR, &ss); 293 294 /* 295 * Don't check for errors, because we don't want to give 296 * out any information. 297 */ 298 pwd = NULL; 299 (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), &pwd); 300 301 /* 302 * Establish the class now, before we might goto 303 * within the next block. pwd can be NULL since it 304 * falls back to the "default" class if it is. 305 */ 306 lc = login_getclass(pwd ? pwd->pw_class : NULL); 307 308 /* 309 * if we have a valid account name, and it doesn't have a 310 * password, or the -f option was specified and the caller 311 * is root or the caller isn't changing their uid, don't 312 * authenticate. 313 */ 314 if (pwd) { 315 if (pwd->pw_uid == 0) 316 rootlogin = 1; 317 318 if (fflag && (uid == 0 || uid == pwd->pw_uid)) { 319 /* already authenticated */ 320 auth_passed = 1; 321 goto skip_auth; 322 } 323 } 324 325 (void)setpriority(PRIO_PROCESS, 0, -4); 326 327 switch(pam_err = pam_authenticate(pamh, pam_silent)) { 328 case PAM_SUCCESS: 329 /* 330 * PAM can change the user, refresh 331 * username, pwd, and lc. 332 */ 333 pam_err = pam_get_item(pamh, PAM_USER, &newuser); 334 if (pam_err != PAM_SUCCESS) 335 PAM_END("pam_get_item(PAM_USER)"); 336 337 username = (char *)newuser; 338 /* 339 * Don't check for errors, because we don't want to give 340 * out any information. 341 */ 342 pwd = NULL; 343 (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), 344 &pwd); 345 lc = login_getpwclass(pwd); 346 auth_passed = 1; 347 348 switch (pam_err = pam_acct_mgmt(pamh, pam_silent)) { 349 case PAM_SUCCESS: 350 break; 351 352 case PAM_NEW_AUTHTOK_REQD: 353 pam_err = pam_chauthtok(pamh, 354 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); 355 356 if (pam_err != PAM_SUCCESS) 357 PAM_END("pam_chauthtok"); 358 break; 359 360 case PAM_AUTH_ERR: 361 case PAM_USER_UNKNOWN: 362 case PAM_MAXTRIES: 363 auth_passed = 0; 364 break; 365 366 default: 367 PAM_END("pam_acct_mgmt"); 368 break; 369 } 370 break; 371 372 case PAM_AUTH_ERR: 373 case PAM_USER_UNKNOWN: 374 case PAM_MAXTRIES: 375 auth_passed = 0; 376 break; 377 378 default: 379 PAM_END("pam_authenticate"); 380 break; 381 } 382 383 (void)setpriority(PRIO_PROCESS, 0, 0); 384 385 skip_auth: 386 /* 387 * If the user exists and authentication passed, 388 * get out of the loop and login the user. 389 */ 390 if (pwd && auth_passed) 391 break; 392 393 (void)printf("Login incorrect or refused on this terminal.\n"); 394 failures++; 395 cnt++; 396 /* 397 * We allow login_retries tries, but after login_backoff 398 * we start backing off. These default to 10 and 3 399 * respectively. 400 */ 401 if (cnt > login_backoff) { 402 if (cnt >= login_retries) { 403 badlogin(username); 404 pam_end(pamh, PAM_SUCCESS); 405 sleepexit(EXIT_FAILURE); 406 } 407 sleep((u_int)((cnt - login_backoff) * 5)); 408 } 409 } 410 411 /* committed to login -- turn off timeout */ 412 (void)alarm((u_int)0); 413 414 endpwent(); 415 416 quietlog = login_getcapbool(lc, "hushlogin", 0); 417 418 /* 419 * Temporarily give up special privileges so we can change 420 * into NFS-mounted homes that are exported for non-root 421 * access and have mode 7x0 422 */ 423 saved_uid = geteuid(); 424 saved_gid = getegid(); 425 nsaved_gids = getgroups(NGROUPS_MAX, saved_gids); 426 427 (void)setegid(pwd->pw_gid); 428 initgroups(username, pwd->pw_gid); 429 (void)seteuid(pwd->pw_uid); 430 431 if (chdir(pwd->pw_dir) != 0) { 432 if (login_getcapbool(lc, "requirehome", 0)) { 433 (void)printf("Home directory %s required\n", 434 pwd->pw_dir); 435 pam_end(pamh, PAM_SUCCESS); 436 exit(EXIT_FAILURE); 437 } 438 439 (void)printf("No home directory %s!\n", pwd->pw_dir); 440 if (chdir("/") == -1) { 441 pam_end(pamh, PAM_SUCCESS); 442 exit(EXIT_FAILURE); 443 } 444 pwd->pw_dir = "/"; 445 (void)printf("Logging in with home = \"/\".\n"); 446 } 447 448 if (!quietlog) { 449 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; 450 pam_silent = quietlog ? PAM_SILENT : 0; 451 } 452 453 /* regain special privileges */ 454 setegid(saved_gid); 455 setgroups(nsaved_gids, saved_gids); 456 seteuid(saved_uid); 457 458 (void)getgrnam_r(TTYGRPNAME, &grs, grbuf, sizeof(grbuf), &grp); 459 (void)chown(ttyn, pwd->pw_uid, 460 (grp != NULL) ? grp->gr_gid : pwd->pw_gid); 461 462 if (ttyaction(ttyn, "login", pwd->pw_name)) 463 (void)printf("Warning: ttyaction failed.\n"); 464 465 /* Nothing else left to fail -- really log in. */ 466 update_db(quietlog, rootlogin, fflag); 467 468 if (nested == NULL && setusercontext(lc, pwd, pwd->pw_uid, 469 LOGIN_SETLOGIN) != 0) { 470 syslog(LOG_ERR, "setusercontext failed"); 471 pam_end(pamh, PAM_SUCCESS); 472 exit(EXIT_FAILURE); 473 } 474 475 if (tty[sizeof("tty")-1] == 'd') 476 syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name); 477 478 479 /* 480 * Establish groups 481 */ 482 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { 483 syslog(LOG_ERR, "setusercontext failed"); 484 pam_end(pamh, PAM_SUCCESS); 485 exit(EXIT_FAILURE); 486 } 487 488 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); 489 if (pam_err != PAM_SUCCESS) 490 PAM_END("pam_setcred"); 491 492 pam_err = pam_open_session(pamh, pam_silent); 493 if (pam_err != PAM_SUCCESS) 494 PAM_END("pam_open_session"); 495 496 /* 497 * Fork because we need to call pam_closesession as root. 498 * Make sure signals cannot kill the parent. 499 * This has been handled in the begining of main. 500 */ 501 502 switch(pid = fork()) { 503 case -1: 504 pam_err = pam_close_session(pamh, 0); 505 if (pam_err != PAM_SUCCESS) { 506 syslog(LOG_ERR, "pam_close_session: %s", 507 pam_strerror(pamh, pam_err)); 508 warnx("pam_close_session: %s", 509 pam_strerror(pamh, pam_err)); 510 } 511 syslog(LOG_ERR, "fork failed: %m"); 512 warn("fork failed"); 513 pam_end(pamh, pam_err); 514 exit(EXIT_FAILURE); 515 break; 516 517 case 0: /* Child */ 518 break; 519 520 default: 521 /* 522 * Parent: wait for the child to terminate 523 * and call pam_close_session. 524 */ 525 if ((xpid = waitpid(pid, &status, 0)) != pid) { 526 pam_err = pam_close_session(pamh, 0); 527 if (pam_err != PAM_SUCCESS) { 528 syslog(LOG_ERR, 529 "pam_close_session: %s", 530 pam_strerror(pamh, pam_err)); 531 warnx("pam_close_session: %s", 532 pam_strerror(pamh, pam_err)); 533 } 534 pam_end(pamh, pam_err); 535 if (xpid != -1) 536 warnx("wrong PID: %d != %d", pid, xpid); 537 else 538 warn("wait for pid %d failed", pid); 539 exit(EXIT_FAILURE); 540 } 541 542 (void)signal(SIGABRT, oabrt); 543 (void)signal(SIGALRM, oalrm); 544 (void)signal(SIGINT, oint); 545 (void)signal(SIGQUIT, oquit); 546 if ((pam_err = pam_close_session(pamh, 0)) != PAM_SUCCESS) { 547 syslog(LOG_ERR, "pam_close_session: %s", 548 pam_strerror(pamh, pam_err)); 549 warnx("pam_close_session: %s", 550 pam_strerror(pamh, pam_err)); 551 } 552 pam_end(pamh, PAM_SUCCESS); 553 exit(EXIT_SUCCESS); 554 break; 555 } 556 557 /* 558 * The child: starting here, we don't have to care about 559 * handling PAM issues if we exit, the parent will do the 560 * job when we exit. 561 * 562 * Destroy environment unless user has requested its preservation. 563 * Try to preserve TERM anyway. 564 */ 565 saved_term = getenv("TERM"); 566 if (!pflag) { 567 environ = envinit; 568 if (saved_term) 569 setenv("TERM", saved_term, 0); 570 } 571 572 if (*pwd->pw_shell == '\0') 573 pwd->pw_shell = _PATH_BSHELL; 574 575 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); 576 if (*shell == '\0') 577 shell = pwd->pw_shell; 578 579 if ((pwd->pw_shell = strdup(shell)) == NULL) { 580 syslog(LOG_ERR, "Cannot alloc mem"); 581 exit(EXIT_FAILURE); 582 } 583 584 (void)setenv("HOME", pwd->pw_dir, 1); 585 (void)setenv("SHELL", pwd->pw_shell, 1); 586 if (term[0] == '\0') { 587 char *tt = (char *)stypeof(tty); 588 589 if (tt == NULL) 590 tt = login_getcapstr(lc, "term", NULL, NULL); 591 592 /* unknown term -> "su" */ 593 (void)strlcpy(term, tt != NULL ? tt : "su", sizeof(term)); 594 } 595 (void)setenv("TERM", term, 0); 596 (void)setenv("LOGNAME", pwd->pw_name, 1); 597 (void)setenv("USER", pwd->pw_name, 1); 598 599 /* 600 * Add PAM environement 601 */ 602 if ((pamenv = pam_getenvlist(pamh)) != NULL) { 603 char **envitem; 604 605 for (envitem = pamenv; *envitem; envitem++) { 606 putenv(*envitem); 607 free(*envitem); 608 } 609 610 free(pamenv); 611 } 612 613 /* This drops root privs */ 614 if (setusercontext(lc, pwd, pwd->pw_uid, 615 (LOGIN_SETALL & ~LOGIN_SETLOGIN)) != 0) { 616 syslog(LOG_ERR, "setusercontext failed"); 617 exit(EXIT_FAILURE); 618 } 619 620 if (!quietlog) { 621 char *fname; 622 623 fname = login_getcapstr(lc, "copyright", NULL, NULL); 624 if (fname != NULL && access(fname, F_OK) == 0) 625 motd(fname); 626 else 627 (void)printf("%s", copyrightstr); 628 629 fname = login_getcapstr(lc, "welcome", NULL, NULL); 630 if (fname == NULL || access(fname, F_OK) != 0) 631 fname = _PATH_MOTDFILE; 632 motd(fname); 633 634 (void)snprintf(tbuf, 635 sizeof(tbuf), "%s/%s", _PATH_MAILDIR, pwd->pw_name); 636 if (stat(tbuf, &st) == 0 && st.st_size != 0) 637 (void)printf("You have %smail.\n", 638 (st.st_mtime > st.st_atime) ? "new " : ""); 639 } 640 641 login_close(lc); 642 643 644 tbuf[0] = '-'; 645 (void)strlcpy(tbuf + 1, (p = strrchr(pwd->pw_shell, '/')) ? 646 p + 1 : pwd->pw_shell, sizeof(tbuf) - 1); 647 648 (void)signal(SIGABRT, oabrt); 649 (void)signal(SIGALRM, oalrm); 650 (void)signal(SIGINT, oint); 651 (void)signal(SIGQUIT, oquit); 652 (void)signal(SIGTSTP, SIG_IGN); 653 654 execlp(pwd->pw_shell, tbuf, NULL); 655 err(EXIT_FAILURE, "%s", pwd->pw_shell); 656 } 657 658 static void 659 usage(void) 660 { 661 (void)fprintf(stderr, 662 "Usage: %s [-fp] [-a address] [-h hostname] [username]\n", 663 getprogname()); 664 exit(EXIT_FAILURE); 665 } 666 667 #if 0 668 static int 669 rootterm(char *ttyn) 670 { 671 struct ttyent *t; 672 673 return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE); 674 } 675 #endif 676
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