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 && creds_set) { \ 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 local_ret = pam_end(pamh, local_ret); \ 85 if (local_ret != PAM_SUCCESS) \ 86 syslog(LOG_ERR, "pam_end: %s", \ 87 pam_strerror(pamh, local_ret)); \ 88 } \ 89 } while (0) 90 91 92 #define PAM_SET_ITEM(what, item) do { \ 93 int local_ret; \ 94 local_ret = pam_set_item(pamh, what, item); \ 95 if (local_ret != PAM_SUCCESS) { \ 96 syslog(LOG_ERR, "pam_set_item(" #what "): %s", \ 97 pam_strerror(pamh, local_ret)); \ 98 errx(1, "pam_set_item(" #what "): %s", \ 99 pam_strerror(pamh, local_ret)); \ 100 } \ 101 } while (0) 102 103 enum tristate { UNSET, YES, NO }; 104 105 static pam_handle_t *pamh = NULL; 106 static int creds_set = 0; 107 static char **environ_pam; 108 109 static char *ontty(void); 110 static int chshell(char *); 111 static void usage(void); 112 static int export_pam_environment(void); 113 static int ok_to_export(const char *); 114 115 extern char **environ; 116 117 int 118 main(int argc, char *argv[]) 119 { 120 struct passwd *pwd; 121 struct pam_conv conv = { openpam_ttyconv, NULL }; 122 enum tristate iscsh; 123 login_cap_t *lc; 124 union { 125 const char **a; 126 char * const *b; 127 } np; 128 uid_t ruid; 129 int asme, ch, asthem, fastlogin, prio, i, setwhat, retcode, 130 statusp, child_pid, child_pgrp, ret_pid, setmaclabel; 131 char *username, *cleanenv, *class, shellbuf[MAXPATHLEN]; 132 const char *p, *user, *shell, *mytty, **nargv; 133 134 struct sigaction sa, sa_int, sa_quit, sa_tstp; 135 136 shell = class = cleanenv = NULL; 137 asme = asthem = fastlogin = statusp = 0; 138 user = "root"; 139 iscsh = UNSET; 140 setmaclabel = 0; 141 142 while ((ch = getopt(argc, argv, "-flmsc:")) != -1) 143 switch ((char)ch) { 144 case 'f': 145 fastlogin = 1; 146 break; 147 case '-': 148 case 'l': 149 asme = 0; 150 asthem = 1; 151 break; 152 case 'm': 153 asme = 1; 154 asthem = 0; 155 break; 156 case 's': 157 setmaclabel = 1; 158 break; 159 case 'c': 160 class = optarg; 161 break; 162 case '?': 163 default: 164 usage(); 165 } 166 167 if (optind < argc) 168 user = argv[optind++]; 169 170 if (user == NULL) 171 usage(); 172 173 if (strlen(user) > MAXLOGNAME - 1) 174 errx(1, "username too long"); 175 176 nargv = malloc(sizeof(char *) * (argc + 4)); 177 if (nargv == NULL) 178 errx(1, "malloc failure"); 179 180 nargv[argc + 3] = NULL; 181 for (i = argc; i >= optind; i--) 182 nargv[i + 3] = argv[i]; 183 np.a = &nargv[i + 3]; 184 185 argv += optind; 186 187 errno = 0; 188 prio = getpriority(PRIO_PROCESS, 0); 189 if (errno) 190 prio = 0; 191 192 setpriority(PRIO_PROCESS, 0, -2); 193 openlog("su", LOG_CONS, LOG_AUTH); 194 195 /* get current login name, real uid and shell */ 196 ruid = getuid(); 197 username = getlogin(); 198 pwd = getpwnam(username); 199 if (username == NULL || pwd == NULL || pwd->pw_uid != ruid) 200 pwd = getpwuid(ruid); 201 if (pwd == NULL) 202 errx(1, "who are you?"); 203 204 username = strdup(pwd->pw_name); 205 if (username == NULL) 206 err(1, "strdup failure"); 207 208 if (asme) { 209 if (pwd->pw_shell != NULL && *pwd->pw_shell != '\0') { 210 /* must copy - pwd memory is recycled */ 211 shell = strncpy(shellbuf, pwd->pw_shell, 212 sizeof(shellbuf)); 213 shellbuf[sizeof(shellbuf) - 1] = '\0'; 214 } 215 else { 216 shell = _PATH_BSHELL; 217 iscsh = NO; 218 } 219 } 220 221 /* Do the whole PAM startup thing */ 222 retcode = pam_start("su", user, &conv, &pamh); 223 if (retcode != PAM_SUCCESS) { 224 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode)); 225 errx(1, "pam_start: %s", pam_strerror(pamh, retcode)); 226 } 227 228 PAM_SET_ITEM(PAM_RUSER, getlogin()); 229 230 mytty = ttyname(STDERR_FILENO); 231 if (!mytty) 232 mytty = "tty"; 233 PAM_SET_ITEM(PAM_TTY, mytty); 234 235 retcode = pam_authenticate(pamh, 0); 236 if (retcode != PAM_SUCCESS) { 237 #if 0 238 syslog(LOG_ERR, "pam_authenticate: %s", 239 pam_strerror(pamh, retcode)); 240 #endif 241 syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s on %s", 242 username, user, mytty); 243 errx(1, "Sorry"); 244 } 245 retcode = pam_get_item(pamh, PAM_USER, (const void **)&p); 246 if (retcode == PAM_SUCCESS) 247 user = p; 248 else 249 syslog(LOG_ERR, "pam_get_item(PAM_USER): %s", 250 pam_strerror(pamh, retcode)); 251 252 retcode = pam_acct_mgmt(pamh, 0); 253 if (retcode == PAM_NEW_AUTHTOK_REQD) { 254 retcode = pam_chauthtok(pamh, 255 PAM_CHANGE_EXPIRED_AUTHTOK); 256 if (retcode != PAM_SUCCESS) { 257 syslog(LOG_ERR, "pam_chauthtok: %s", 258 pam_strerror(pamh, retcode)); 259 errx(1, "Sorry"); 260 } 261 } 262 if (retcode != PAM_SUCCESS) { 263 syslog(LOG_ERR, "pam_acct_mgmt: %s", 264 pam_strerror(pamh, retcode)); 265 errx(1, "Sorry"); 266 } 267 268 /* get target login information, default to root */ 269 pwd = getpwnam(user); 270 if (pwd == NULL) 271 errx(1, "unknown login: %s", user); 272 if (class == NULL) 273 lc = login_getpwclass(pwd); 274 else { 275 if (ruid != 0) 276 errx(1, "only root may use -c"); 277 lc = login_getclass(class); 278 if (lc == NULL) 279 errx(1, "unknown class: %s", class); 280 } 281 282 /* if asme and non-standard target shell, must be root */ 283 if (asme) { 284 if (ruid != 0 && !chshell(pwd->pw_shell)) 285 errx(1, "permission denied (shell)."); 286 } 287 else if (pwd->pw_shell && *pwd->pw_shell) { 288 shell = pwd->pw_shell; 289 iscsh = UNSET; 290 } 291 else { 292 shell = _PATH_BSHELL; 293 iscsh = NO; 294 } 295 296 /* if we're forking a csh, we want to slightly muck the args */ 297 if (iscsh == UNSET) { 298 p = strrchr(shell, '/'); 299 if (p) 300 ++p; 301 else 302 p = shell; 303 iscsh = strcmp(p, "csh") ? (strcmp(p, "tcsh") ? NO : YES) : YES; 304 } 305 setpriority(PRIO_PROCESS, 0, prio); 306 307 /* 308 * PAM modules might add supplementary groups in pam_setcred(), so 309 * initialize them first. 310 */ 311 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0) 312 err(1, "setusercontext"); 313 314 retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED); 315 if (retcode != PAM_SUCCESS) 316 syslog(LOG_ERR, "pam_setcred(pamh, PAM_ESTABLISH_CRED): %s", 317 pam_strerror(pamh, retcode)); 318 else 319 creds_set = 1; 320 321 /* 322 * We must fork() before setuid() because we need to call 323 * pam_setcred(pamh, PAM_DELETE_CRED) as root. 324 */ 325 sa.sa_flags = SA_RESTART; 326 sa.sa_handler = SIG_IGN; 327 sigemptyset(&sa.sa_mask); 328 sigaction(SIGINT, &sa, &sa_int); 329 sigaction(SIGQUIT, &sa, &sa_quit); 330 sigaction(SIGTSTP, &sa, &sa_tstp); 331 332 statusp = 1; 333 child_pid = fork(); 334 switch (child_pid) { 335 default: 336 while ((ret_pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) { 337 if (WIFSTOPPED(statusp)) { 338 kill(getpid(), SIGSTOP); 339 child_pgrp = getpgid(child_pid); 340 if (tcgetpgrp(1) == getpgrp()) { 341 tcsetpgrp(1, child_pgrp); 342 kill(child_pid, SIGCONT); 343 } 344 statusp = 1; 345 continue; 346 } 347 break; 348 } 349 if (ret_pid == -1) 350 err(1, "waitpid"); 351 PAM_END(); 352 exit(statusp); 353 case -1: 354 err(1, "fork"); 355 PAM_END(); 356 exit(1); 357 case 0: 358 sigaction(SIGINT, &sa_int, NULL); 359 sigaction(SIGQUIT, &sa_quit, NULL); 360 sigaction(SIGTSTP, &sa_tstp, NULL); 361 /* 362 * Set all user context except for: Environmental variables 363 * Umask Login records (wtmp, etc) Path 364 */ 365 setwhat = LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK | 366 LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP | 367 LOGIN_SETMAC); 368 /* 369 * If -s is present, also set the MAC label. 370 */ 371 if (setmaclabel) 372 setwhat |= LOGIN_SETMAC; 373 /* 374 * Don't touch resource/priority settings if -m has been used 375 * or -l and -c hasn't, and we're not su'ing to root. 376 */ 377 if ((asme || (!asthem && class == NULL)) && pwd->pw_uid) 378 setwhat &= ~(LOGIN_SETPRIORITY | LOGIN_SETRESOURCES); 379 if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0) 380 err(1, "setusercontext"); 381 382 if (!asme) { 383 if (asthem) { 384 p = getenv("TERM"); 385 environ = &cleanenv; 386 387 /* 388 * Add any environmental variables that the 389 * PAM modules may have set. 390 */ 391 environ_pam = pam_getenvlist(pamh); 392 if (environ_pam) 393 export_pam_environment(); 394 395 /* set the su'd user's environment & umask */ 396 setusercontext(lc, pwd, pwd->pw_uid, 397 LOGIN_SETPATH | LOGIN_SETUMASK | 398 LOGIN_SETENV); 399 if (p) 400 setenv("TERM", p, 1); 401 if (chdir(pwd->pw_dir) < 0) 402 errx(1, "no directory"); 403 } 404 if (asthem || pwd->pw_uid) 405 setenv("USER", pwd->pw_name, 1); 406 setenv("HOME", pwd->pw_dir, 1); 407 setenv("SHELL", shell, 1); 408 } 409 login_close(lc); 410 411 if (iscsh == YES) { 412 if (fastlogin) 413 *np.a-- = "-f"; 414 if (asme) 415 *np.a-- = "-m"; 416 } 417 /* csh strips the first character... */ 418 *np.a = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 419 420 if (ruid != 0) 421 syslog(LOG_NOTICE, "%s to %s%s", username, user, 422 ontty()); 423 424 execv(shell, np.b); 425 err(1, "%s", shell); 426 } 427 } 428 429 static int 430 export_pam_environment(void) 431 { 432 char **pp; 433 434 for (pp = environ_pam; *pp != NULL; pp++) { 435 if (ok_to_export(*pp)) 436 putenv(*pp); 437 free(*pp); 438 } 439 return PAM_SUCCESS; 440 } 441 442 /* 443 * Sanity checks on PAM environmental variables: 444 * - Make sure there is an '=' in the string. 445 * - Make sure the string doesn't run on too long. 446 * - Do not export certain variables. This list was taken from the 447 * Solaris pam_putenv(3) man page. 448 */ 449 static int 450 ok_to_export(const char *s) 451 { 452 static const char *noexport[] = { 453 "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH", 454 "IFS", "PATH", NULL 455 }; 456 const char **pp; 457 size_t n; 458 459 if (strlen(s) > 1024 || strchr(s, '=') == NULL) 460 return 0; 461 if (strncmp(s, "LD_", 3) == 0) 462 return 0; 463 for (pp = noexport; *pp != NULL; pp++) { 464 n = strlen(*pp); 465 if (s[n] == '=' && strncmp(s, *pp, n) == 0) 466 return 0; 467 } 468 return 1; 469 } 470 471 static void 472 usage(void) 473 { 474 475 fprintf(stderr, "usage: su [-] [-flms] [-c class] [login [args]]\n"); 476 exit(1); 477 } 478 479 static int 480 chshell(char *sh) 481 { 482 int r; 483 char *cp; 484 485 r = 0; 486 setusershell(); 487 do { 488 cp = getusershell(); 489 r = strcmp(cp, sh); 490 } while (!r && cp != NULL); 491 endusershell(); 492 return r; 493 } 494 495 static char * 496 ontty(void) 497 { 498 char *p; 499 static char buf[MAXPATHLEN + 4]; 500 501 buf[0] = 0; 502 p = ttyname(STDERR_FILENO); 503 if (p) 504 snprintf(buf, sizeof(buf), " on %s", p); 505 return buf; 506 } 507