1 /* 2 * Copyright (c) 2002, 2005 Networks Associates Technologies, Inc. 3 * All rights reserved. 4 * 5 * Portions of this software were developed for the FreeBSD Project by 6 * ThinkSec AS and NAI Labs, the Security Research Division of Network 7 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 8 * ("CBOSS"), as part of the DARPA CHATS research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 * Copyright (c) 1988, 1993, 1994 33 * The Regents of the University of California. All rights reserved. 34 * 35 * Redistribution and use in source and binary forms, with or without 36 * modification, are permitted provided that the following conditions 37 * are met: 38 * 1. Redistributions of source code must retain the above copyright 39 * notice, this list of conditions and the following disclaimer. 40 * 2. Redistributions in binary form must reproduce the above copyright 41 * notice, this list of conditions and the following disclaimer in the 42 * documentation and/or other materials provided with the distribution. 43 * 3. Neither the name of the University nor the names of its contributors 44 * may be used to endorse or promote products derived from this software 45 * without specific prior written permission. 46 * 47 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 48 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 50 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 51 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 52 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 53 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 54 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 55 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 56 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 57 * SUCH DAMAGE. 58 * 59 * @(#)su.c 8.3 (Berkeley) 4/2/94 60 * $FreeBSD: src/usr.bin/su/su.c,v 1.88 2008/06/04 19:16:54 dwmalone Exp $ 61 * $DragonFly: src/usr.bin/su/su.c,v 1.9 2006/01/12 13:43:11 corecode Exp $ 62 */ 63 64 #include <sys/param.h> 65 #include <sys/time.h> 66 #include <sys/resource.h> 67 #include <sys/wait.h> 68 69 #ifdef USE_BSM_AUDIT 70 #include <bsm/libbsm.h> 71 #include <bsm/audit_uevents.h> 72 #endif 73 74 #include <err.h> 75 #include <errno.h> 76 #include <grp.h> 77 #include <login_cap.h> 78 #include <paths.h> 79 #include <pwd.h> 80 #include <signal.h> 81 #include <stdio.h> 82 #include <stdlib.h> 83 #include <string.h> 84 #include <syslog.h> 85 #include <unistd.h> 86 #include <stdarg.h> 87 88 #include <security/pam_appl.h> 89 #include <security/openpam.h> 90 91 #define PAM_END() do { \ 92 int local_ret; \ 93 if (pamh != NULL) { \ 94 local_ret = pam_setcred(pamh, PAM_DELETE_CRED); \ 95 if (local_ret != PAM_SUCCESS) \ 96 syslog(LOG_ERR, "pam_setcred: %s", \ 97 pam_strerror(pamh, local_ret)); \ 98 if (asthem) { \ 99 local_ret = pam_close_session(pamh, 0); \ 100 if (local_ret != PAM_SUCCESS) \ 101 syslog(LOG_ERR, "pam_close_session: %s",\ 102 pam_strerror(pamh, local_ret)); \ 103 } \ 104 local_ret = pam_end(pamh, local_ret); \ 105 if (local_ret != PAM_SUCCESS) \ 106 syslog(LOG_ERR, "pam_end: %s", \ 107 pam_strerror(pamh, local_ret)); \ 108 } \ 109 } while (0) 110 111 112 #define PAM_SET_ITEM(what, item) do { \ 113 int local_ret; \ 114 local_ret = pam_set_item(pamh, what, item); \ 115 if (local_ret != PAM_SUCCESS) { \ 116 syslog(LOG_ERR, "pam_set_item(" #what "): %s", \ 117 pam_strerror(pamh, local_ret)); \ 118 errx(1, "pam_set_item(" #what "): %s", \ 119 pam_strerror(pamh, local_ret)); \ 120 /* NOTREACHED */ \ 121 } \ 122 } while (0) 123 124 enum tristate { UNSET, YES, NO }; 125 126 static pam_handle_t *pamh = NULL; 127 static char **environ_pam; 128 129 static char *ontty(void); 130 static int chshell(const char *); 131 static void usage(void) __dead2; 132 static void export_pam_environment(void); 133 static int ok_to_export(const char *); 134 135 extern char **environ; 136 137 int 138 main(int argc, char **argv) 139 { 140 static char *cleanenv; 141 struct passwd *pwd; 142 struct pam_conv conv = { openpam_ttyconv, NULL }; 143 enum tristate iscsh; 144 login_cap_t *lc; 145 union { 146 const char **a; 147 char * const *b; 148 } np; 149 uid_t ruid; 150 pid_t child_pid, child_pgrp, pid; 151 int asme, ch, asthem, fastlogin, prio, i, retcode, 152 statusp; 153 u_int setwhat; 154 char *username, *class, shellbuf[MAXPATHLEN]; 155 const char *p = p, *user, *shell, *mytty, **nargv; 156 const void *v; 157 struct sigaction sa, sa_int, sa_quit, sa_pipe; 158 int temp, fds[2]; 159 #ifdef USE_BSM_AUDIT 160 const char *aerr; 161 au_id_t auid; 162 #endif 163 164 shell = class = cleanenv = NULL; 165 asme = asthem = fastlogin = statusp = 0; 166 user = "root"; 167 iscsh = UNSET; 168 169 while ((ch = getopt(argc, argv, "-flmc:")) != -1) 170 switch ((char)ch) { 171 case 'f': 172 fastlogin = 1; 173 break; 174 case '-': 175 case 'l': 176 asme = 0; 177 asthem = 1; 178 break; 179 case 'm': 180 asme = 1; 181 asthem = 0; 182 break; 183 case 'c': 184 class = optarg; 185 break; 186 case '?': 187 default: 188 usage(); 189 /* NOTREACHED */ 190 } 191 192 if (optind < argc && strcmp(argv[optind], "-") == 0) { 193 asme = 0; 194 asthem = 1; 195 optind++; 196 } 197 198 if (optind < argc) 199 user = argv[optind++]; 200 201 if (user == NULL) 202 usage(); 203 /* NOTREACHED */ 204 205 /* 206 * Try to provide more helpful debugging output if su(1) is running 207 * non-setuid, or was run from a file system not mounted setuid. 208 */ 209 if (geteuid() != 0) 210 errx(1, "not running setuid"); 211 212 #ifdef USE_BSM_AUDIT 213 if (getauid(&auid) < 0 && errno != ENOSYS) { 214 syslog(LOG_AUTH | LOG_ERR, "getauid: %s", strerror(errno)); 215 errx(1, "Permission denied"); 216 } 217 #endif 218 if (strlen(user) > MAXLOGNAME - 1) { 219 #ifdef USE_BSM_AUDIT 220 if (audit_submit(AUE_su, auid, 221 1, EPERM, "username too long: '%s'", user)) 222 errx(1, "Permission denied"); 223 #endif 224 errx(1, "username too long"); 225 } 226 227 nargv = malloc(sizeof(char *) * (size_t)(argc + 4)); 228 if (nargv == NULL) 229 errx(1, "malloc failure"); 230 231 nargv[argc + 3] = NULL; 232 for (i = argc; i >= optind; i--) 233 nargv[i + 3] = argv[i]; 234 np.a = &nargv[i + 3]; 235 236 argv += optind; 237 238 errno = 0; 239 prio = getpriority(PRIO_PROCESS, 0); 240 if (errno) 241 prio = 0; 242 243 setpriority(PRIO_PROCESS, 0, -2); 244 openlog("su", LOG_CONS, LOG_AUTH); 245 246 /* get current login name, real uid and shell */ 247 ruid = getuid(); 248 username = getlogin(); 249 pwd = getpwnam(username); 250 if (username == NULL || pwd == NULL || pwd->pw_uid != ruid) 251 pwd = getpwuid(ruid); 252 if (pwd == NULL) { 253 #ifdef USE_BSM_AUDIT 254 if (audit_submit(AUE_su, auid, 1, EPERM, 255 "unable to determine invoking subject: '%s'", username)) 256 errx(1, "Permission denied"); 257 #endif 258 errx(1, "who are you?"); 259 } 260 261 username = strdup(pwd->pw_name); 262 if (username == NULL) 263 err(1, "strdup failure"); 264 265 if (asme) { 266 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') { 267 /* must copy - pwd memory is recycled */ 268 shell = strncpy(shellbuf, pwd->pw_shell, 269 sizeof(shellbuf)); 270 shellbuf[sizeof(shellbuf) - 1] = '\0'; 271 } 272 else { 273 shell = _PATH_BSHELL; 274 iscsh = NO; 275 } 276 } 277 278 /* Do the whole PAM startup thing */ 279 retcode = pam_start("su", user, &conv, &pamh); 280 if (retcode != PAM_SUCCESS) { 281 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode)); 282 errx(1, "pam_start: %s", pam_strerror(pamh, retcode)); 283 } 284 285 PAM_SET_ITEM(PAM_RUSER, username); 286 287 mytty = ttyname(STDERR_FILENO); 288 if (!mytty) 289 mytty = "tty"; 290 PAM_SET_ITEM(PAM_TTY, mytty); 291 292 retcode = pam_authenticate(pamh, 0); 293 if (retcode != PAM_SUCCESS) { 294 #ifdef USE_BSM_AUDIT 295 if (audit_submit(AUE_su, auid, 1, EPERM, "bad su %s to %s on %s", 296 username, user, mytty)) 297 errx(1, "Permission denied"); 298 #endif 299 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s", 300 username, user, mytty); 301 errx(1, "Sorry"); 302 } 303 #ifdef USE_BSM_AUDIT 304 if (audit_submit(AUE_su, auid, 0, 0, "successful authentication")) 305 errx(1, "Permission denied"); 306 #endif 307 retcode = pam_get_item(pamh, PAM_USER, &v); 308 if (retcode == PAM_SUCCESS) 309 user = v; 310 else 311 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s", 312 pam_strerror(pamh, retcode)); 313 pwd = getpwnam(user); 314 if (pwd == NULL) { 315 #ifdef USE_BSM_AUDIT 316 if (audit_submit(AUE_su, auid, 1, EPERM, 317 "unknown subject: %s", user)) 318 errx(1, "Permission denied"); 319 #endif 320 errx(1, "unknown login: %s", user); 321 } 322 323 retcode = pam_acct_mgmt(pamh, 0); 324 if (retcode == PAM_NEW_AUTHTOK_REQD) { 325 retcode = pam_chauthtok(pamh, 326 PAM_CHANGE_EXPIRED_AUTHTOK); 327 if (retcode != PAM_SUCCESS) { 328 #ifdef USE_BSM_AUDIT 329 aerr = pam_strerror(pamh, retcode); 330 if (aerr == NULL) 331 aerr = "Unknown PAM error"; 332 if (audit_submit(AUE_su, auid, 1, EPERM, 333 "pam_chauthtok: %s", aerr)) 334 errx(1, "Permission denied"); 335 #endif 336 syslog(LOG_ERR, "pam_chauthtok: %s", 337 pam_strerror(pamh, retcode)); 338 errx(1, "Sorry"); 339 } 340 } 341 if (retcode != PAM_SUCCESS) { 342 #ifdef USE_BSM_AUDIT 343 if (audit_submit(AUE_su, auid, 1, EPERM, "pam_acct_mgmt: %s", 344 pam_strerror(pamh, retcode))) 345 errx(1, "Permission denied"); 346 #endif 347 syslog(LOG_ERR, "pam_acct_mgmt: %s", 348 pam_strerror(pamh, retcode)); 349 errx(1, "Sorry"); 350 } 351 352 /* get target login information */ 353 if (class == NULL) 354 lc = login_getpwclass(pwd); 355 else { 356 if (ruid != 0) { 357 #ifdef USE_BSM_AUDIT 358 if (audit_submit(AUE_su, auid, 1, EPERM, 359 "only root may use -c")) 360 errx(1, "Permission denied"); 361 #endif 362 errx(1, "only root may use -c"); 363 } 364 lc = login_getclass(class); 365 if (lc == NULL) 366 errx(1, "unknown class: %s", class); 367 } 368 369 /* if asme and non-standard target shell, must be root */ 370 if (asme) { 371 if (ruid != 0 && !chshell(pwd->pw_shell)) 372 errx(1, "permission denied (shell)"); 373 } 374 else if (pwd->pw_shell && *pwd->pw_shell) { 375 shell = pwd->pw_shell; 376 iscsh = UNSET; 377 } 378 else { 379 shell = _PATH_BSHELL; 380 iscsh = NO; 381 } 382 383 /* if we're forking a csh, we want to slightly muck the args */ 384 if (iscsh == UNSET) { 385 p = strrchr(shell, '/'); 386 if (p) 387 ++p; 388 else 389 p = shell; 390 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES; 391 } 392 setpriority(PRIO_PROCESS, 0, prio); 393 394 /* 395 * PAM modules might add supplementary groups in pam_setcred(), so 396 * initialize them first. 397 */ 398 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0) 399 err(1, "setusercontext"); 400 401 retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED); 402 if (retcode != PAM_SUCCESS) { 403 syslog(LOG_ERR, "pam_setcred: %s", 404 pam_strerror(pamh, retcode)); 405 errx(1, "failed to establish credentials."); 406 } 407 if (asthem) { 408 retcode = pam_open_session(pamh, 0); 409 if (retcode != PAM_SUCCESS) { 410 syslog(LOG_ERR, "pam_open_session: %s", 411 pam_strerror(pamh, retcode)); 412 errx(1, "failed to open session."); 413 } 414 } 415 416 /* 417 * We must fork() before setuid() because we need to call 418 * pam_setcred(pamh, PAM_DELETE_CRED) as root. 419 */ 420 sa.sa_flags = SA_RESTART; 421 sa.sa_handler = SIG_IGN; 422 sigemptyset(&sa.sa_mask); 423 sigaction(SIGINT, &sa, &sa_int); 424 sigaction(SIGQUIT, &sa, &sa_quit); 425 sigaction(SIGPIPE, &sa, &sa_pipe); 426 sa.sa_handler = SIG_DFL; 427 sigaction(SIGTSTP, &sa, NULL); 428 statusp = 1; 429 if (pipe(fds) == -1) { 430 PAM_END(); 431 err(1, "pipe"); 432 } 433 child_pid = fork(); 434 switch (child_pid) { 435 default: 436 sa.sa_handler = SIG_IGN; 437 sigaction(SIGTTOU, &sa, NULL); 438 close(fds[0]); 439 setpgid(child_pid, child_pid); 440 if (tcgetpgrp(STDERR_FILENO) == getpgrp()) 441 tcsetpgrp(STDERR_FILENO, child_pid); 442 close(fds[1]); 443 sigaction(SIGPIPE, &sa_pipe, NULL); 444 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) { 445 if (WIFSTOPPED(statusp)) { 446 child_pgrp = getpgid(child_pid); 447 if (tcgetpgrp(STDERR_FILENO) == child_pgrp) 448 tcsetpgrp(STDERR_FILENO, getpgrp()); 449 kill(getpid(), SIGSTOP); 450 if (tcgetpgrp(STDERR_FILENO) == getpgrp()) { 451 child_pgrp = getpgid(child_pid); 452 tcsetpgrp(STDERR_FILENO, child_pgrp); 453 } 454 kill(child_pid, SIGCONT); 455 statusp = 1; 456 continue; 457 } 458 break; 459 } 460 tcsetpgrp(STDERR_FILENO, getpgrp()); 461 if (pid == -1) 462 err(1, "waitpid"); 463 PAM_END(); 464 exit(WEXITSTATUS(statusp)); 465 case -1: 466 PAM_END(); 467 err(1, "fork"); 468 case 0: 469 close(fds[1]); 470 read(fds[0], &temp, 1); 471 close(fds[0]); 472 sigaction(SIGPIPE, &sa_pipe, NULL); 473 sigaction(SIGINT, &sa_int, NULL); 474 sigaction(SIGQUIT, &sa_quit, NULL); 475 476 /* 477 * Set all user context except for: Environmental variables 478 * Umask Login records (wtmp, etc) Path 479 * XXX Missing LOGIN_SETMAC 480 */ 481 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK | 482 LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP); 483 #if 0 484 /* 485 * If -s is present, also set the MAC label. 486 */ 487 if (setmaclabel) 488 setwhat |= LOGIN_SETMAC; 489 #endif 490 /* 491 * Don't touch resource/priority settings if -m has been used 492 * or -l and -c hasn't, and we're not su'ing to root. 493 */ 494 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid) 495 setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES); 496 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0) 497 err(1, "setusercontext"); 498 499 if (!asme) { 500 if (asthem) { 501 p = getenv("TERM"); 502 environ = &cleanenv; 503 } 504 505 if (asthem || pwd->pw_uid) { 506 if (setenv("USER", pwd->pw_name, 1) == -1) { 507 err(1, "setenv: cannot set USER=%s", 508 pwd->pw_name); 509 } 510 } 511 if (setenv("HOME", pwd->pw_dir, 1) == -1) { 512 err(1, "setenv: cannot set HOME=%s", 513 pwd->pw_dir); 514 } 515 if (setenv("SHELL", shell, 1) == -1) 516 err(1, "setenv: cannot set SHELL=%s", shell); 517 518 if (asthem) { 519 /* 520 * Add any environmental variables that the 521 * PAM modules may have set. 522 */ 523 environ_pam = pam_getenvlist(pamh); 524 if (environ_pam) 525 export_pam_environment(); 526 527 /* set the su'd user's environment & umask */ 528 setusercontext(lc, pwd, pwd->pw_uid, 529 LOGIN_SETPATH | LOGIN_SETUMASK | 530 LOGIN_SETENV); 531 if (p) { 532 if (setenv("TERM", p, 1) == -1) { 533 err(1, 534 "setenv: cannot set TERM=%s", 535 p); 536 } 537 } 538 539 p = pam_getenv(pamh, "HOME"); 540 if (chdir(p ? p : pwd->pw_dir) < 0) 541 errx(1, "no directory"); 542 } 543 } 544 login_close(lc); 545 546 if (iscsh == YES) { 547 if (fastlogin) 548 *np.a-- = "-f"; 549 if (asme) 550 *np.a-- = "-m"; 551 } 552 /* csh strips the first character... */ 553 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 554 555 if (ruid != 0) 556 syslog(LOG_NOTICE, "%s to %s%s", username, user, 557 ontty()); 558 559 execv(shell, np.b); 560 err(1, "%s", shell); 561 } 562 } 563 564 static void 565 export_pam_environment(void) 566 { 567 char **pp; 568 char *p; 569 570 for (pp = environ_pam; *pp != NULL; pp++) { 571 if (ok_to_export(*pp)) { 572 p = strchr(*pp, '='); 573 *p = '\0'; 574 if (setenv(*pp, p + 1, 1) == -1) 575 err(1, "setenv: cannot set %s=%s", *pp, p + 1); 576 } 577 free(*pp); 578 } 579 } 580 581 /* 582 * Sanity checks on PAM environmental variables: 583 * - Make sure there is an '=' in the string. 584 * - Make sure the string doesn't run on too long. 585 * - Do not export certain variables. This list was taken from the 586 * Solaris pam_putenv(3) man page. 587 * Note that if the user is chrooted, PAM may have a better idea than we 588 * do of where her home directory is. 589 */ 590 static int 591 ok_to_export(const char *s) 592 { 593 static const char *noexport[] = { 594 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH", 595 "IFS", "PATH", NULL 596 }; 597 const char **pp; 598 size_t n; 599 600 if (strlen(s) > 1024 || strchr(s, '=') == NULL) 601 return 0; 602 if (strncmp(s, "LD_", 3) == 0) 603 return 0; 604 for (pp = noexport; *pp != NULL; pp++) { 605 n = strlen(*pp); 606 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 607 return 0; 608 } 609 return 1; 610 } 611 612 static void 613 usage(void) 614 { 615 616 fprintf(stderr, "usage: su [-] [-flm] [-c class] [login [args]]\n"); 617 exit(1); 618 /* NOTREACHED */ 619 } 620 621 static int 622 chshell(const char *sh) 623 { 624 int r; 625 char *cp; 626 627 r = 0; 628 setusershell(); 629 while ((cp = getusershell()) != NULL && !r) 630 r = (strcmp(cp, sh) == 0); 631 endusershell(); 632 return r; 633 } 634 635 static char * 636 ontty(void) 637 { 638 char *p; 639 static char buf[MAXPATHLEN + 4]; 640 641 buf[0] = 0; 642 p = ttyname(STDERR_FILENO); 643 if (p) 644 snprintf(buf, sizeof(buf), " on %s", p); 645 return buf; 646 } 647