1 /* 2 * Copyright (c) 1988, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 2002 Networks Associates Technologies, Inc. 5 * All rights reserved. 6 * 7 * Portions of this software were developed for the FreeBSD Project by 8 * ThinkSec AS and NAI Labs, the Security Research Division of Network 9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 10 * ("CBOSS"), as part of the DARPA CHATS research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 */ 40 41 #ifndef lint 42 static const char copyright[] = 43 "@(#) Copyright (c) 1988, 1993, 1994\n\ 44 The Regents of the University of California. All rights reserved.\n"; 45 #endif /* not lint */ 46 47 #if 0 48 #ifndef lint 49 static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94"; 50 #endif /* not lint */ 51 #endif 52 53 #include <sys/cdefs.h> 54 __FBSDID("$FreeBSD$"); 55 56 #include <sys/param.h> 57 #include <sys/time.h> 58 #include <sys/resource.h> 59 #include <sys/wait.h> 60 61 #include <err.h> 62 #include <errno.h> 63 #include <grp.h> 64 #include <login_cap.h> 65 #include <paths.h> 66 #include <pwd.h> 67 #include <signal.h> 68 #include <stdio.h> 69 #include <stdlib.h> 70 #include <string.h> 71 #include <syslog.h> 72 #include <unistd.h> 73 74 #include <security/pam_appl.h> 75 #include <security/openpam.h> 76 77 #define PAM_END() do { \ 78 int local_ret; \ 79 if (pamh != NULL) { \ 80 local_ret = pam_setcred(pamh, PAM_DELETE_CRED); \ 81 if (local_ret != PAM_SUCCESS) \ 82 syslog(LOG_ERR, "pam_setcred: %s", \ 83 pam_strerror(pamh, local_ret)); \ 84 if (asthem) { \ 85 local_ret = pam_close_session(pamh, 0); \ 86 if (local_ret != PAM_SUCCESS) \ 87 syslog(LOG_ERR, "pam_close_session: %s",\ 88 pam_strerror(pamh, local_ret)); \ 89 } \ 90 local_ret = pam_end(pamh, local_ret); \ 91 if (local_ret != PAM_SUCCESS) \ 92 syslog(LOG_ERR, "pam_end: %s", \ 93 pam_strerror(pamh, local_ret)); \ 94 } \ 95 } while (0) 96 97 98 #define PAM_SET_ITEM(what, item) do { \ 99 int local_ret; \ 100 local_ret = pam_set_item(pamh, what, item); \ 101 if (local_ret != PAM_SUCCESS) { \ 102 syslog(LOG_ERR, "pam_set_item(" #what "): %s", \ 103 pam_strerror(pamh, local_ret)); \ 104 errx(1, "pam_set_item(" #what "): %s", \ 105 pam_strerror(pamh, local_ret)); \ 106 /* NOTREACHED */ \ 107 } \ 108 } while (0) 109 110 enum tristate { UNSET, YES, NO }; 111 112 static pam_handle_t *pamh = NULL; 113 static char **environ_pam; 114 115 static char *ontty(void); 116 static int chshell(const char *); 117 static void usage(void) __dead2; 118 static void export_pam_environment(void); 119 static int ok_to_export(const char *); 120 121 extern char **environ; 122 123 int 124 main(int argc, char *argv[]) 125 { 126 static char *cleanenv; 127 struct passwd *pwd; 128 struct pam_conv conv = { openpam_ttyconv, NULL }; 129 enum tristate iscsh; 130 login_cap_t *lc; 131 union { 132 const char **a; 133 char * const *b; 134 } np; 135 uid_t ruid; 136 pid_t child_pid, child_pgrp, pid; 137 int asme, ch, asthem, fastlogin, prio, i, retcode, 138 statusp, setmaclabel; 139 u_int setwhat; 140 char *username, *class, shellbuf[MAXPATHLEN]; 141 const char *p, *user, *shell, *mytty, **nargv; 142 struct sigaction sa, sa_int, sa_quit, sa_pipe; 143 int temp, fds[2]; 144 145 shell = class = cleanenv = NULL; 146 asme = asthem = fastlogin = statusp = 0; 147 user = "root"; 148 iscsh = UNSET; 149 setmaclabel = 0; 150 151 while ((ch = getopt(argc, argv, "-flmsc:")) != -1) 152 switch ((char)ch) { 153 case 'f': 154 fastlogin = 1; 155 break; 156 case '-': 157 case 'l': 158 asme = 0; 159 asthem = 1; 160 break; 161 case 'm': 162 asme = 1; 163 asthem = 0; 164 break; 165 case 's': 166 setmaclabel = 1; 167 break; 168 case 'c': 169 class = optarg; 170 break; 171 case '?': 172 default: 173 usage(); 174 /* NOTREACHED */ 175 } 176 177 if (optind < argc) 178 user = argv[optind++]; 179 180 if (user == NULL) 181 usage(); 182 /* NOTREACHED */ 183 184 if (strlen(user) > MAXLOGNAME - 1) 185 errx(1, "username too long"); 186 187 nargv = malloc(sizeof(char *) * (size_t)(argc + 4)); 188 if (nargv == NULL) 189 errx(1, "malloc failure"); 190 191 nargv[argc + 3] = NULL; 192 for (i = argc; i >= optind; i--) 193 nargv[i + 3] = argv[i]; 194 np.a = &nargv[i + 3]; 195 196 argv += optind; 197 198 errno = 0; 199 prio = getpriority(PRIO_PROCESS, 0); 200 if (errno) 201 prio = 0; 202 203 setpriority(PRIO_PROCESS, 0, -2); 204 openlog("su", LOG_CONS, LOG_AUTH); 205 206 /* get current login name, real uid and shell */ 207 ruid = getuid(); 208 username = getlogin(); 209 pwd = getpwnam(username); 210 if (username == NULL || pwd == NULL || pwd->pw_uid != ruid) 211 pwd = getpwuid(ruid); 212 if (pwd == NULL) 213 errx(1, "who are you?"); 214 215 username = strdup(pwd->pw_name); 216 if (username == NULL) 217 err(1, "strdup failure"); 218 219 if (asme) { 220 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') { 221 /* must copy - pwd memory is recycled */ 222 shell = strncpy(shellbuf, pwd->pw_shell, 223 sizeof(shellbuf)); 224 shellbuf[sizeof(shellbuf) - 1] = '\0'; 225 } 226 else { 227 shell = _PATH_BSHELL; 228 iscsh = NO; 229 } 230 } 231 232 /* Do the whole PAM startup thing */ 233 retcode = pam_start("su", user, &conv, &pamh); 234 if (retcode != PAM_SUCCESS) { 235 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode)); 236 errx(1, "pam_start: %s", pam_strerror(pamh, retcode)); 237 } 238 239 PAM_SET_ITEM(PAM_RUSER, username); 240 241 mytty = ttyname(STDERR_FILENO); 242 if (!mytty) 243 mytty = "tty"; 244 PAM_SET_ITEM(PAM_TTY, mytty); 245 246 retcode = pam_authenticate(pamh, 0); 247 if (retcode != PAM_SUCCESS) { 248 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s", 249 username, user, mytty); 250 errx(1, "Sorry"); 251 } 252 retcode = pam_get_item(pamh, PAM_USER, (const void **)&p); 253 if (retcode == PAM_SUCCESS) 254 user = p; 255 else 256 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s", 257 pam_strerror(pamh, retcode)); 258 pwd = getpwnam(user); 259 if (pwd == NULL) 260 errx(1, "unknown login: %s", user); 261 262 retcode = pam_acct_mgmt(pamh, 0); 263 if (retcode == PAM_NEW_AUTHTOK_REQD) { 264 retcode = pam_chauthtok(pamh, 265 PAM_CHANGE_EXPIRED_AUTHTOK); 266 if (retcode != PAM_SUCCESS) { 267 syslog(LOG_ERR, "pam_chauthtok: %s", 268 pam_strerror(pamh, retcode)); 269 errx(1, "Sorry"); 270 } 271 } 272 if (retcode != PAM_SUCCESS) { 273 syslog(LOG_ERR, "pam_acct_mgmt: %s", 274 pam_strerror(pamh, retcode)); 275 errx(1, "Sorry"); 276 } 277 278 /* get target login information */ 279 if (class == NULL) 280 lc = login_getpwclass(pwd); 281 else { 282 if (ruid != 0) 283 errx(1, "only root may use -c"); 284 lc = login_getclass(class); 285 if (lc == NULL) 286 errx(1, "unknown class: %s", class); 287 } 288 289 /* if asme and non-standard target shell, must be root */ 290 if (asme) { 291 if (ruid != 0 && !chshell(pwd->pw_shell)) 292 errx(1, "permission denied (shell)"); 293 } 294 else if (pwd->pw_shell && *pwd->pw_shell) { 295 shell = pwd->pw_shell; 296 iscsh = UNSET; 297 } 298 else { 299 shell = _PATH_BSHELL; 300 iscsh = NO; 301 } 302 303 /* if we're forking a csh, we want to slightly muck the args */ 304 if (iscsh == UNSET) { 305 p = strrchr(shell, '/'); 306 if (p) 307 ++p; 308 else 309 p = shell; 310 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES; 311 } 312 setpriority(PRIO_PROCESS, 0, prio); 313 314 /* Switch to home directory */ 315 if (asthem) { 316 if (chdir(pwd->pw_dir) < 0) 317 errx(1, "no directory"); 318 } 319 320 /* 321 * PAM modules might add supplementary groups in pam_setcred(), so 322 * initialize them first. 323 */ 324 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0) 325 err(1, "setusercontext"); 326 327 retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED); 328 if (retcode != PAM_SUCCESS) { 329 syslog(LOG_ERR, "pam_setcred: %s", 330 pam_strerror(pamh, retcode)); 331 errx(1, "failed to establish credentials."); 332 } 333 if (asthem) { 334 retcode = pam_open_session(pamh, 0); 335 if (retcode != PAM_SUCCESS) { 336 syslog(LOG_ERR, "pam_open_session: %s", 337 pam_strerror(pamh, retcode)); 338 errx(1, "failed to open session."); 339 } 340 } 341 342 /* 343 * We must fork() before setuid() because we need to call 344 * pam_setcred(pamh, PAM_DELETE_CRED) as root. 345 */ 346 sa.sa_flags = SA_RESTART; 347 sa.sa_handler = SIG_IGN; 348 sigemptyset(&sa.sa_mask); 349 sigaction(SIGINT, &sa, &sa_int); 350 sigaction(SIGQUIT, &sa, &sa_quit); 351 sigaction(SIGPIPE, &sa, &sa_pipe); 352 sa.sa_handler = SIG_DFL; 353 sigaction(SIGTSTP, &sa, NULL); 354 statusp = 1; 355 if (pipe(fds) == -1) { 356 PAM_END(); 357 err(1, "pipe"); 358 } 359 child_pid = fork(); 360 switch (child_pid) { 361 default: 362 sa.sa_handler = SIG_IGN; 363 sigaction(SIGTTOU, &sa, NULL); 364 close(fds[0]); 365 setpgid(child_pid, child_pid); 366 tcsetpgrp(STDERR_FILENO, child_pid); 367 close(fds[1]); 368 sigaction(SIGPIPE, &sa_pipe, NULL); 369 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) { 370 if (WIFSTOPPED(statusp)) { 371 kill(getpid(), SIGSTOP); 372 child_pgrp = getpgid(child_pid); 373 tcsetpgrp(1, child_pgrp); 374 kill(child_pid, SIGCONT); 375 statusp = 1; 376 continue; 377 } 378 break; 379 } 380 tcsetpgrp(STDERR_FILENO, getpgrp()); 381 if (pid == -1) 382 err(1, "waitpid"); 383 PAM_END(); 384 exit(WEXITSTATUS(statusp)); 385 case -1: 386 PAM_END(); 387 err(1, "fork"); 388 case 0: 389 close(fds[1]); 390 read(fds[0], &temp, 1); 391 close(fds[0]); 392 sigaction(SIGPIPE, &sa_pipe, NULL); 393 sigaction(SIGINT, &sa_int, NULL); 394 sigaction(SIGQUIT, &sa_quit, NULL); 395 396 /* 397 * Set all user context except for: Environmental variables 398 * Umask Login records (wtmp, etc) Path 399 */ 400 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK | 401 LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP | 402 LOGIN_SETMAC); 403 /* 404 * If -s is present, also set the MAC label. 405 */ 406 if (setmaclabel) 407 setwhat |= LOGIN_SETMAC; 408 /* 409 * Don't touch resource/priority settings if -m has been used 410 * or -l and -c hasn't, and we're not su'ing to root. 411 */ 412 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid) 413 setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES); 414 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0) 415 err(1, "setusercontext"); 416 417 if (!asme) { 418 if (asthem) { 419 p = getenv("TERM"); 420 environ = &cleanenv; 421 } 422 423 if (asthem || pwd->pw_uid) 424 setenv("USER", pwd->pw_name, 1); 425 setenv("HOME", pwd->pw_dir, 1); 426 setenv("SHELL", shell, 1); 427 428 if (asthem) { 429 /* 430 * Add any environmental variables that the 431 * PAM modules may have set. 432 */ 433 environ_pam = pam_getenvlist(pamh); 434 if (environ_pam) 435 export_pam_environment(); 436 437 /* set the su'd user's environment & umask */ 438 setusercontext(lc, pwd, pwd->pw_uid, 439 LOGIN_SETPATH | LOGIN_SETUMASK | 440 LOGIN_SETENV); 441 if (p) 442 setenv("TERM", p, 1); 443 } 444 } 445 login_close(lc); 446 447 if (iscsh == YES) { 448 if (fastlogin) 449 *np.a-- = "-f"; 450 if (asme) 451 *np.a-- = "-m"; 452 } 453 /* csh strips the first character... */ 454 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 455 456 if (ruid != 0) 457 syslog(LOG_NOTICE, "%s to %s%s", username, user, 458 ontty()); 459 460 execv(shell, np.b); 461 err(1, "%s", shell); 462 } 463 } 464 465 static void 466 export_pam_environment(void) 467 { 468 char **pp; 469 470 for (pp = environ_pam; *pp != NULL; pp++) { 471 if (ok_to_export(*pp)) 472 putenv(*pp); 473 free(*pp); 474 } 475 } 476 477 /* 478 * Sanity checks on PAM environmental variables: 479 * - Make sure there is an '=' in the string. 480 * - Make sure the string doesn't run on too long. 481 * - Do not export certain variables. This list was taken from the 482 * Solaris pam_putenv(3) man page. 483 * Note that if the user is chrooted, PAM may have a better idea than we 484 * do of where her home directory is. 485 */ 486 static int 487 ok_to_export(const char *s) 488 { 489 static const char *noexport[] = { 490 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH", 491 "IFS", "PATH", NULL 492 }; 493 const char **pp; 494 size_t n; 495 496 if (strlen(s) > 1024 || strchr(s, '=') == NULL) 497 return 0; 498 if (strncmp(s, "LD_", 3) == 0) 499 return 0; 500 for (pp = noexport; *pp != NULL; pp++) { 501 n = strlen(*pp); 502 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 503 return 0; 504 } 505 return 1; 506 } 507 508 static void 509 usage(void) 510 { 511 512 fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n"); 513 exit(1); 514 /* NOTREACHED */ 515 } 516 517 static int 518 chshell(const char *sh) 519 { 520 int r; 521 char *cp; 522 523 r = 0; 524 setusershell(); 525 while ((cp = getusershell()) != NULL && !r) 526 r = (strcmp(cp, sh) == 0); 527 endusershell(); 528 return r; 529 } 530 531 static char * 532 ontty(void) 533 { 534 char *p; 535 static char buf[MAXPATHLEN + 4]; 536 537 buf[0] = 0; 538 p = ttyname(STDERR_FILENO); 539 if (p) 540 snprintf(buf, sizeof(buf), " on %s", p); 541 return buf; 542 } 543