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