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 #ifndef lint 48 #if 0 49 static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94"; 50 #endif 51 static const char rcsid[] = 52 "$FreeBSD$"; 53 #endif /* not lint */ 54 55 #include <sys/param.h> 56 #include <sys/time.h> 57 #include <sys/resource.h> 58 #include <sys/wait.h> 59 60 #include <err.h> 61 #include <errno.h> 62 #include <grp.h> 63 #include <libutil.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 } \ 107 } while (0) 108 109 enum tristate { UNSET, YES, NO }; 110 111 static pam_handle_t *pamh = NULL; 112 static char **environ_pam; 113 114 static char *ontty(void); 115 static int chshell(char *); 116 static void usage(void); 117 static int export_pam_environment(void); 118 static int ok_to_export(const char *); 119 120 extern char **environ; 121 122 int 123 main(int argc, char *argv[]) 124 { 125 struct passwd *pwd; 126 struct pam_conv conv = { openpam_ttyconv, NULL }; 127 enum tristate iscsh; 128 login_cap_t *lc; 129 union { 130 const char **a; 131 char * const *b; 132 } np; 133 uid_t ruid; 134 pid_t child_pid, child_pgrp, pid; 135 int asme, ch, asthem, fastlogin, prio, i, setwhat, retcode, 136 statusp, setmaclabel; 137 char *username, *cleanenv, *class, shellbuf[MAXPATHLEN]; 138 const char *p, *user, *shell, *mytty, **nargv; 139 struct sigaction sa, sa_int, sa_quit, sa_pipe; 140 int temp, fds[2]; 141 142 shell = class = cleanenv = NULL; 143 asme = asthem = fastlogin = statusp = 0; 144 user = "root"; 145 iscsh = UNSET; 146 setmaclabel = 0; 147 148 while ((ch = getopt(argc, argv, "-flmsc:")) != -1) 149 switch ((char)ch) { 150 case 'f': 151 fastlogin = 1; 152 break; 153 case '-': 154 case 'l': 155 asme = 0; 156 asthem = 1; 157 break; 158 case 'm': 159 asme = 1; 160 asthem = 0; 161 break; 162 case 's': 163 setmaclabel = 1; 164 break; 165 case 'c': 166 class = optarg; 167 break; 168 case '?': 169 default: 170 usage(); 171 } 172 173 if (optind < argc) 174 user = argv[optind++]; 175 176 if (user == NULL) 177 usage(); 178 179 if (strlen(user) > MAXLOGNAME - 1) 180 errx(1, "username too long"); 181 182 nargv = malloc(sizeof(char *) * (argc + 4)); 183 if (nargv == NULL) 184 errx(1, "malloc failure"); 185 186 nargv[argc + 3] = NULL; 187 for (i = argc; i >= optind; i--) 188 nargv[i + 3] = argv[i]; 189 np.a = &nargv[i + 3]; 190 191 argv += optind; 192 193 errno = 0; 194 prio = getpriority(PRIO_PROCESS, 0); 195 if (errno) 196 prio = 0; 197 198 setpriority(PRIO_PROCESS, 0, -2); 199 openlog("su", LOG_CONS, LOG_AUTH); 200 201 /* get current login name, real uid and shell */ 202 ruid = getuid(); 203 username = getlogin(); 204 pwd = getpwnam(username); 205 if (username == NULL || pwd == NULL || pwd->pw_uid != ruid) 206 pwd = getpwuid(ruid); 207 if (pwd == NULL) 208 errx(1, "who are you?"); 209 210 username = strdup(pwd->pw_name); 211 if (username == NULL) 212 err(1, "strdup failure"); 213 214 if (asme) { 215 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') { 216 /* must copy - pwd memory is recycled */ 217 shell = strncpy(shellbuf, pwd->pw_shell, 218 sizeof(shellbuf)); 219 shellbuf[sizeof(shellbuf) - 1] = '\0'; 220 } 221 else { 222 shell = _PATH_BSHELL; 223 iscsh = NO; 224 } 225 } 226 227 /* Do the whole PAM startup thing */ 228 retcode = pam_start("su", user, &conv, &pamh); 229 if (retcode != PAM_SUCCESS) { 230 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode)); 231 errx(1, "pam_start: %s", pam_strerror(pamh, retcode)); 232 } 233 234 PAM_SET_ITEM(PAM_RUSER, username); 235 236 mytty = ttyname(STDERR_FILENO); 237 if (!mytty) 238 mytty = "tty"; 239 PAM_SET_ITEM(PAM_TTY, mytty); 240 241 retcode = pam_authenticate(pamh, 0); 242 if (retcode != PAM_SUCCESS) { 243 #if 0 244 syslog(LOG_ERR, "pam_authenticate: %s", 245 pam_strerror(pamh, retcode)); 246 #endif 247 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s", 248 username, user, mytty); 249 errx(1, "Sorry"); 250 } 251 retcode = pam_get_item(pamh, PAM_USER, (const void **)&p); 252 if (retcode == PAM_SUCCESS) 253 user = p; 254 else 255 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s", 256 pam_strerror(pamh, retcode)); 257 258 retcode = pam_acct_mgmt(pamh, 0); 259 if (retcode == PAM_NEW_AUTHTOK_REQD) { 260 retcode = pam_chauthtok(pamh, 261 PAM_CHANGE_EXPIRED_AUTHTOK); 262 if (retcode != PAM_SUCCESS) { 263 syslog(LOG_ERR, "pam_chauthtok: %s", 264 pam_strerror(pamh, retcode)); 265 errx(1, "Sorry"); 266 } 267 } 268 if (retcode != PAM_SUCCESS) { 269 syslog(LOG_ERR, "pam_acct_mgmt: %s", 270 pam_strerror(pamh, retcode)); 271 errx(1, "Sorry"); 272 } 273 274 /* get target login information, default to root */ 275 pwd = getpwnam(user); 276 if (pwd == NULL) 277 errx(1, "unknown login: %s", user); 278 if (class == NULL) 279 lc = login_getpwclass(pwd); 280 else { 281 if (ruid != 0) 282 errx(1, "only root may use -c"); 283 lc = login_getclass(class); 284 if (lc == NULL) 285 errx(1, "unknown class: %s", class); 286 } 287 288 /* if asme and non-standard target shell, must be root */ 289 if (asme) { 290 if (ruid != 0 && !chshell(pwd->pw_shell)) 291 errx(1, "permission denied (shell)."); 292 } 293 else if (pwd->pw_shell && *pwd->pw_shell) { 294 shell = pwd->pw_shell; 295 iscsh = UNSET; 296 } 297 else { 298 shell = _PATH_BSHELL; 299 iscsh = NO; 300 } 301 302 /* if we're forking a csh, we want to slightly muck the args */ 303 if (iscsh == UNSET) { 304 p = strrchr(shell, '/'); 305 if (p) 306 ++p; 307 else 308 p = shell; 309 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES; 310 } 311 setpriority(PRIO_PROCESS, 0, prio); 312 313 /* Switch to home directory */ 314 if (asthem) { 315 if (chdir(pwd->pw_dir) < 0) 316 errx(1, "no directory"); 317 } 318 319 /* 320 * PAM modules might add supplementary groups in pam_setcred(), so 321 * initialize them first. 322 */ 323 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0) 324 err(1, "setusercontext"); 325 326 retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED); 327 if (retcode != PAM_SUCCESS) { 328 syslog(LOG_ERR, "pam_setcred: %s", 329 pam_strerror(pamh, retcode)); 330 errx(1, "failed to establish credentials."); 331 } 332 if (asthem) { 333 retcode = pam_open_session(pamh, 0); 334 if (retcode != PAM_SUCCESS) { 335 syslog(LOG_ERR, "pam_open_session: %s", 336 pam_strerror(pamh, retcode)); 337 errx(1, "failed to open session."); 338 } 339 } 340 341 /* 342 * We must fork() before setuid() because we need to call 343 * pam_setcred(pamh, PAM_DELETE_CRED) as root. 344 */ 345 sa.sa_flags = SA_RESTART; 346 sa.sa_handler = SIG_IGN; 347 sigemptyset(&sa.sa_mask); 348 sigaction(SIGINT, &sa, &sa_int); 349 sigaction(SIGQUIT, &sa, &sa_quit); 350 sigaction(SIGPIPE, &sa, &sa_pipe); 351 sa.sa_handler = SIG_DFL; 352 sigaction(SIGTSTP, &sa, NULL); 353 statusp = 1; 354 if (pipe(fds) == -1) { 355 err(1, "pipe"); 356 PAM_END(); 357 exit(1); 358 } 359 child_pid = fork(); 360 switch (child_pid) { 361 default: 362 close(fds[0]); 363 setpgid(child_pid, child_pid); 364 tcsetpgrp(1, child_pid); 365 close(fds[1]); 366 sigaction(SIGPIPE, &sa_pipe, NULL); 367 while ((pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) { 368 if (WIFSTOPPED(statusp)) { 369 kill(getpid(), SIGSTOP); 370 child_pgrp = getpgid(child_pid); 371 tcsetpgrp(1, child_pgrp); 372 kill(child_pid, SIGCONT); 373 statusp = 1; 374 continue; 375 } 376 break; 377 } 378 if (pid == -1) 379 err(1, "waitpid"); 380 PAM_END(); 381 exit(statusp); 382 case -1: 383 err(1, "fork"); 384 PAM_END(); 385 exit(1); 386 case 0: 387 close(fds[1]); 388 read(fds[0], &temp, 1); 389 close(fds[0]); 390 sigaction(SIGPIPE, &sa_pipe, NULL); 391 sigaction(SIGINT, &sa_int, NULL); 392 sigaction(SIGQUIT, &sa_quit, NULL); 393 394 /* 395 * Set all user context except for: Environmental variables 396 * Umask Login records (wtmp, etc) Path 397 */ 398 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK | 399 LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP | 400 LOGIN_SETMAC); 401 /* 402 * If -s is present, also set the MAC label. 403 */ 404 if (setmaclabel) 405 setwhat |= LOGIN_SETMAC; 406 /* 407 * Don't touch resource/priority settings if -m has been used 408 * or -l and -c hasn't, and we're not su'ing to root. 409 */ 410 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid) 411 setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES); 412 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0) 413 err(1, "setusercontext"); 414 415 if (!asme) { 416 if (asthem) { 417 p = getenv("TERM"); 418 environ = &cleanenv; 419 } 420 421 if (asthem || pwd->pw_uid) 422 setenv("USER", pwd->pw_name, 1); 423 setenv("HOME", pwd->pw_dir, 1); 424 setenv("SHELL", shell, 1); 425 426 if (asthem) { 427 /* 428 * Add any environmental variables that the 429 * PAM modules may have set. 430 */ 431 environ_pam = pam_getenvlist(pamh); 432 if (environ_pam) 433 export_pam_environment(); 434 435 /* set the su'd user's environment & umask */ 436 setusercontext(lc, pwd, pwd->pw_uid, 437 LOGIN_SETPATH | LOGIN_SETUMASK | 438 LOGIN_SETENV); 439 if (p) 440 setenv("TERM", p, 1); 441 } 442 } 443 login_close(lc); 444 445 if (iscsh == YES) { 446 if (fastlogin) 447 *np.a-- = "-f"; 448 if (asme) 449 *np.a-- = "-m"; 450 } 451 /* csh strips the first character... */ 452 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 453 454 if (ruid != 0) 455 syslog(LOG_NOTICE, "%s to %s%s", username, user, 456 ontty()); 457 458 execv(shell, np.b); 459 err(1, "%s", shell); 460 } 461 } 462 463 static int 464 export_pam_environment(void) 465 { 466 char **pp; 467 468 for (pp = environ_pam; *pp != NULL; pp++) { 469 if (ok_to_export(*pp)) 470 putenv(*pp); 471 free(*pp); 472 } 473 return PAM_SUCCESS; 474 } 475 476 /* 477 * Sanity checks on PAM environmental variables: 478 * - Make sure there is an '=' in the string. 479 * - Make sure the string doesn't run on too long. 480 * - Do not export certain variables. This list was taken from the 481 * Solaris pam_putenv(3) man page. 482 * Note that if the user is chrooted, PAM may have a better idea than we 483 * do of where her home directory is. 484 */ 485 static int 486 ok_to_export(const char *s) 487 { 488 static const char *noexport[] = { 489 "SHELL", /* "HOME", */ "LOGNAME", "MAIL", "CDPATH", 490 "IFS", "PATH", NULL 491 }; 492 const char **pp; 493 size_t n; 494 495 if (strlen(s) > 1024 || strchr(s, '=') == NULL) 496 return 0; 497 if (strncmp(s, "LD_", 3) == 0) 498 return 0; 499 for (pp = noexport; *pp != NULL; pp++) { 500 n = strlen(*pp); 501 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 502 return 0; 503 } 504 return 1; 505 } 506 507 static void 508 usage(void) 509 { 510 511 fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n"); 512 exit(1); 513 } 514 515 static int 516 chshell(char *sh) 517 { 518 int r; 519 char *cp; 520 521 r = 0; 522 setusershell(); 523 do { 524 cp = getusershell(); 525 r = strcmp(cp, sh); 526 } while (!r && cp != NULL); 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