login_pam.c revision 1.22
1 /* $NetBSD: login_pam.c,v 1.22 2012/04/23 09:27:36 martin 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 1.22 2012/04/23 09:27:36 martin 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 = trimloginname(*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 username = trimloginname(getloginname()); 244 } 245 rootlogin = 0; 246 auth_passed = 0; 247 248 /* 249 * Note if trying multiple user names; log failures for 250 * previous user name, but don't bother logging one failure 251 * for nonexistent name (mistyped username). 252 */ 253 if (failures && strcmp(tbuf, username)) { 254 if (failures > (pwd ? 0 : 1)) 255 badlogin(tbuf); 256 failures = 0; 257 } 258 259 #define PAM_END(msg) do { \ 260 syslog(LOG_ERR, "%s: %s", msg, pam_strerror(pamh, pam_err)); \ 261 warnx("%s: %s", msg, pam_strerror(pamh, pam_err)); \ 262 pam_end(pamh, pam_err); \ 263 sleepexit(EXIT_FAILURE); \ 264 } while (/*CONSTCOND*/0) 265 266 pam_err = pam_start("login", username, &pamc, &pamh); 267 if (pam_err != PAM_SUCCESS) { 268 if (pamh != NULL) 269 PAM_END("pam_start"); 270 /* Things went really bad... */ 271 syslog(LOG_ERR, "pam_start failed: %s", 272 pam_strerror(pamh, pam_err)); 273 errx(EXIT_FAILURE, "pam_start failed"); 274 } 275 276 #define PAM_SET_ITEM(item, var) do { \ 277 pam_err = pam_set_item(pamh, (item), (var)); \ 278 if (pam_err != PAM_SUCCESS) \ 279 PAM_END("pam_set_item(" # item ")"); \ 280 } while (/*CONSTCOND*/0) 281 282 /* 283 * Fill hostname tty, and nested user 284 */ 285 PAM_SET_ITEM(PAM_RHOST, hostname); 286 PAM_SET_ITEM(PAM_TTY, tty); 287 if (nested) 288 PAM_SET_ITEM(PAM_NUSER, nested); 289 if (have_ss) 290 PAM_SET_ITEM(PAM_SOCKADDR, &ss); 291 292 /* 293 * Don't check for errors, because we don't want to give 294 * out any information. 295 */ 296 pwd = NULL; 297 (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), &pwd); 298 299 /* 300 * Establish the class now, before we might goto 301 * within the next block. pwd can be NULL since it 302 * falls back to the "default" class if it is. 303 */ 304 lc = login_getclass(pwd ? pwd->pw_class : NULL); 305 306 /* 307 * if we have a valid account name, and it doesn't have a 308 * password, or the -f option was specified and the caller 309 * is root or the caller isn't changing their uid, don't 310 * authenticate. 311 */ 312 if (pwd) { 313 if (pwd->pw_uid == 0) 314 rootlogin = 1; 315 316 if (fflag && (uid == 0 || uid == pwd->pw_uid)) { 317 /* already authenticated */ 318 auth_passed = 1; 319 goto skip_auth; 320 } 321 } 322 323 (void)setpriority(PRIO_PROCESS, 0, -4); 324 325 switch(pam_err = pam_authenticate(pamh, pam_silent)) { 326 case PAM_SUCCESS: 327 /* 328 * PAM can change the user, refresh 329 * username, pwd, and lc. 330 */ 331 pam_err = pam_get_item(pamh, PAM_USER, &newuser); 332 if (pam_err != PAM_SUCCESS) 333 PAM_END("pam_get_item(PAM_USER)"); 334 335 username = newuser; 336 /* 337 * Don't check for errors, because we don't want to give 338 * out any information. 339 */ 340 pwd = NULL; 341 (void)getpwnam_r(username, &pwres, pwbuf, sizeof(pwbuf), 342 &pwd); 343 lc = login_getpwclass(pwd); 344 auth_passed = 1; 345 346 switch (pam_err = pam_acct_mgmt(pamh, pam_silent)) { 347 case PAM_SUCCESS: 348 break; 349 350 case PAM_NEW_AUTHTOK_REQD: 351 pam_err = pam_chauthtok(pamh, 352 pam_silent|PAM_CHANGE_EXPIRED_AUTHTOK); 353 354 if (pam_err != PAM_SUCCESS) 355 PAM_END("pam_chauthtok"); 356 break; 357 358 case PAM_AUTH_ERR: 359 case PAM_USER_UNKNOWN: 360 case PAM_MAXTRIES: 361 auth_passed = 0; 362 break; 363 364 default: 365 PAM_END("pam_acct_mgmt"); 366 break; 367 } 368 break; 369 370 case PAM_AUTH_ERR: 371 case PAM_USER_UNKNOWN: 372 case PAM_MAXTRIES: 373 auth_passed = 0; 374 break; 375 376 default: 377 PAM_END("pam_authenticate"); 378 break; 379 } 380 381 (void)setpriority(PRIO_PROCESS, 0, 0); 382 383 skip_auth: 384 /* 385 * If the user exists and authentication passed, 386 * get out of the loop and login the user. 387 */ 388 if (pwd && auth_passed) 389 break; 390 391 (void)printf("Login incorrect or refused on this terminal.\n"); 392 failures++; 393 cnt++; 394 /* 395 * We allow login_retries tries, but after login_backoff 396 * we start backing off. These default to 10 and 3 397 * respectively. 398 */ 399 if (cnt > login_backoff) { 400 if (cnt >= login_retries) { 401 badlogin(username); 402 pam_end(pamh, PAM_SUCCESS); 403 sleepexit(EXIT_FAILURE); 404 } 405 sleep((u_int)((cnt - login_backoff) * 5)); 406 } 407 } 408 409 /* committed to login -- turn off timeout */ 410 (void)alarm((u_int)0); 411 412 endpwent(); 413 414 quietlog = login_getcapbool(lc, "hushlogin", 0); 415 416 /* 417 * Temporarily give up special privileges so we can change 418 * into NFS-mounted homes that are exported for non-root 419 * access and have mode 7x0 420 */ 421 saved_uid = geteuid(); 422 saved_gid = getegid(); 423 nsaved_gids = getgroups(NGROUPS_MAX, saved_gids); 424 425 (void)setegid(pwd->pw_gid); 426 initgroups(username, pwd->pw_gid); 427 (void)seteuid(pwd->pw_uid); 428 429 if (chdir(pwd->pw_dir) != 0) { 430 if (login_getcapbool(lc, "requirehome", 0)) { 431 (void)printf("Home directory %s required\n", 432 pwd->pw_dir); 433 pam_end(pamh, PAM_SUCCESS); 434 exit(EXIT_FAILURE); 435 } 436 437 (void)printf("No home directory %s!\n", pwd->pw_dir); 438 if (chdir("/") == -1) { 439 pam_end(pamh, PAM_SUCCESS); 440 exit(EXIT_FAILURE); 441 } 442 pwd->pw_dir = __UNCONST("/"); 443 (void)printf("Logging in with home = \"/\".\n"); 444 } 445 446 if (!quietlog) { 447 quietlog = access(_PATH_HUSHLOGIN, F_OK) == 0; 448 pam_silent = quietlog ? PAM_SILENT : 0; 449 } 450 451 /* regain special privileges */ 452 setegid(saved_gid); 453 setgroups(nsaved_gids, saved_gids); 454 seteuid(saved_uid); 455 456 (void)getgrnam_r(TTYGRPNAME, &grs, grbuf, sizeof(grbuf), &grp); 457 (void)chown(ttyn, pwd->pw_uid, 458 (grp != NULL) ? grp->gr_gid : pwd->pw_gid); 459 460 if (ttyaction(ttyn, "login", pwd->pw_name)) 461 (void)printf("Warning: ttyaction failed.\n"); 462 463 /* Nothing else left to fail -- really log in. */ 464 update_db(quietlog, rootlogin, fflag); 465 466 if (nested == NULL && setusercontext(lc, pwd, pwd->pw_uid, 467 LOGIN_SETLOGIN) != 0) { 468 syslog(LOG_ERR, "setusercontext failed"); 469 pam_end(pamh, PAM_SUCCESS); 470 exit(EXIT_FAILURE); 471 } 472 473 if (tty[sizeof("tty")-1] == 'd') 474 syslog(LOG_INFO, "DIALUP %s, %s", tty, pwd->pw_name); 475 476 477 /* 478 * Establish groups 479 */ 480 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { 481 syslog(LOG_ERR, "setusercontext failed"); 482 pam_end(pamh, PAM_SUCCESS); 483 exit(EXIT_FAILURE); 484 } 485 486 pam_err = pam_setcred(pamh, pam_silent|PAM_ESTABLISH_CRED); 487 if (pam_err != PAM_SUCCESS) 488 PAM_END("pam_setcred"); 489 490 pam_err = pam_open_session(pamh, pam_silent); 491 if (pam_err != PAM_SUCCESS) 492 PAM_END("pam_open_session"); 493 494 /* 495 * Fork because we need to call pam_closesession as root. 496 * Make sure signals cannot kill the parent. 497 * This has been handled in the begining of main. 498 */ 499 500 switch(pid = fork()) { 501 case -1: 502 pam_err = pam_close_session(pamh, 0); 503 if (pam_err != PAM_SUCCESS) { 504 syslog(LOG_ERR, "pam_close_session: %s", 505 pam_strerror(pamh, pam_err)); 506 warnx("pam_close_session: %s", 507 pam_strerror(pamh, pam_err)); 508 } 509 syslog(LOG_ERR, "fork failed: %m"); 510 warn("fork failed"); 511 pam_end(pamh, pam_err); 512 exit(EXIT_FAILURE); 513 break; 514 515 case 0: /* Child */ 516 break; 517 518 default: 519 /* 520 * Parent: wait for the child to terminate 521 * and call pam_close_session. 522 */ 523 if ((xpid = waitpid(pid, &status, 0)) != pid) { 524 pam_err = pam_close_session(pamh, 0); 525 if (pam_err != PAM_SUCCESS) { 526 syslog(LOG_ERR, 527 "pam_close_session: %s", 528 pam_strerror(pamh, pam_err)); 529 warnx("pam_close_session: %s", 530 pam_strerror(pamh, pam_err)); 531 } 532 pam_end(pamh, pam_err); 533 if (xpid != -1) 534 warnx("wrong PID: %d != %d", pid, xpid); 535 else 536 warn("wait for pid %d failed", pid); 537 exit(EXIT_FAILURE); 538 } 539 540 (void)signal(SIGABRT, oabrt); 541 (void)signal(SIGALRM, oalrm); 542 (void)signal(SIGINT, oint); 543 (void)signal(SIGQUIT, oquit); 544 if ((pam_err = pam_close_session(pamh, 0)) != PAM_SUCCESS) { 545 syslog(LOG_ERR, "pam_close_session: %s", 546 pam_strerror(pamh, pam_err)); 547 warnx("pam_close_session: %s", 548 pam_strerror(pamh, pam_err)); 549 } 550 pam_end(pamh, PAM_SUCCESS); 551 exit(EXIT_SUCCESS); 552 break; 553 } 554 555 /* 556 * The child: starting here, we don't have to care about 557 * handling PAM issues if we exit, the parent will do the 558 * job when we exit. 559 * 560 * Destroy environment unless user has requested its preservation. 561 * Try to preserve TERM anyway. 562 */ 563 saved_term = getenv("TERM"); 564 if (!pflag) { 565 environ = envinit; 566 if (saved_term) 567 setenv("TERM", saved_term, 0); 568 } 569 570 if (*pwd->pw_shell == '\0') 571 pwd->pw_shell = __UNCONST(_PATH_BSHELL); 572 573 shell = login_getcapstr(lc, "shell", pwd->pw_shell, pwd->pw_shell); 574 if (*shell == '\0') 575 shell = pwd->pw_shell; 576 577 if ((pwd->pw_shell = strdup(shell)) == NULL) { 578 syslog(LOG_ERR, "Cannot alloc mem"); 579 exit(EXIT_FAILURE); 580 } 581 582 (void)setenv("HOME", pwd->pw_dir, 1); 583 (void)setenv("SHELL", pwd->pw_shell, 1); 584 if (term[0] == '\0') { 585 const char *tt = stypeof(tty); 586 587 if (tt == NULL) 588 tt = login_getcapstr(lc, "term", NULL, NULL); 589 590 /* unknown term -> "su" */ 591 (void)strlcpy(term, tt != NULL ? tt : "su", sizeof(term)); 592 } 593 (void)setenv("TERM", term, 0); 594 (void)setenv("LOGNAME", pwd->pw_name, 1); 595 (void)setenv("USER", pwd->pw_name, 1); 596 597 /* 598 * Add PAM environement 599 */ 600 if ((pamenv = pam_getenvlist(pamh)) != NULL) { 601 char **envitem; 602 603 for (envitem = pamenv; *envitem; envitem++) { 604 putenv(*envitem); 605 free(*envitem); 606 } 607 608 free(pamenv); 609 } 610 611 /* This drops root privs */ 612 if (setusercontext(lc, pwd, pwd->pw_uid, 613 (LOGIN_SETALL & ~LOGIN_SETLOGIN)) != 0) { 614 syslog(LOG_ERR, "setusercontext failed"); 615 exit(EXIT_FAILURE); 616 } 617 618 if (!quietlog) { 619 const char *fname; 620 621 fname = login_getcapstr(lc, "copyright", NULL, NULL); 622 if (fname != NULL && access(fname, F_OK) == 0) 623 motd(fname); 624 else 625 (void)printf("%s", copyrightstr); 626 627 fname = login_getcapstr(lc, "welcome", NULL, NULL); 628 if (fname == NULL || access(fname, F_OK) != 0) 629 fname = _PATH_MOTDFILE; 630 motd(fname); 631 632 (void)snprintf(tbuf, 633 sizeof(tbuf), "%s/%s", _PATH_MAILDIR, pwd->pw_name); 634 if (stat(tbuf, &st) == 0 && st.st_size != 0) 635 (void)printf("You have %smail.\n", 636 (st.st_mtime > st.st_atime) ? "new " : ""); 637 } 638 639 login_close(lc); 640 641 642 tbuf[0] = '-'; 643 (void)strlcpy(tbuf + 1, (p = strrchr(pwd->pw_shell, '/')) ? 644 p + 1 : pwd->pw_shell, sizeof(tbuf) - 1); 645 646 (void)signal(SIGABRT, oabrt); 647 (void)signal(SIGALRM, oalrm); 648 (void)signal(SIGINT, oint); 649 (void)signal(SIGQUIT, oquit); 650 (void)signal(SIGTSTP, SIG_IGN); 651 652 execlp(pwd->pw_shell, tbuf, NULL); 653 err(EXIT_FAILURE, "%s", pwd->pw_shell); 654 } 655 656 static void 657 usage(void) 658 { 659 (void)fprintf(stderr, 660 "Usage: %s [-fp] [-a address] [-h hostname] [username]\n", 661 getprogname()); 662 exit(EXIT_FAILURE); 663 } 664 665 #if 0 666 static int 667 rootterm(char *ttyn) 668 { 669 struct ttyent *t; 670 671 return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE); 672 } 673 #endif 674
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