1 /* 2 * Copyright (c) 1988 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 char copyright[] = 36 "@(#) Copyright (c) 1988 The Regents of the University of California.\n\ 37 All rights reserved.\n"; 38 #endif /* not lint */ 39 40 #ifndef lint 41 /*static char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";*/ 42 static char rcsid[] = "$Id: su.c,v 1.10 1994/05/24 06:52:23 deraadt Exp $"; 43 #endif /* not lint */ 44 45 #include <sys/param.h> 46 #include <sys/time.h> 47 #include <sys/resource.h> 48 #include <syslog.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <pwd.h> 52 #include <grp.h> 53 #include <string.h> 54 #include <unistd.h> 55 #include <paths.h> 56 57 #ifdef KERBEROS 58 #include <kerberosIV/des.h> 59 #include <kerberosIV/krb.h> 60 #include <netdb.h> 61 62 #define ARGSTR "-Kflm" 63 64 int use_kerberos = 1; 65 #else 66 #define ARGSTR "-flm" 67 #endif 68 69 extern char *crypt(); 70 int chshell(); 71 72 int 73 main(argc, argv) 74 int argc; 75 char **argv; 76 { 77 extern char **environ; 78 extern int errno, optind; 79 register struct passwd *pwd; 80 register char *p, **g; 81 struct group *gr; 82 uid_t ruid, getuid(); 83 int asme, ch, asthem, fastlogin, prio; 84 enum { UNSET, YES, NO } iscsh = UNSET; 85 char *user, *shell, *avshell, *username, *cleanenv[10], **np; 86 char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN]; 87 char *getpass(), *getenv(), *getlogin(), *ontty(); 88 89 asme = asthem = fastlogin = 0; 90 while ((ch = getopt(argc, argv, ARGSTR)) != EOF) 91 switch((char)ch) { 92 #ifdef KERBEROS 93 case 'K': 94 use_kerberos = 0; 95 break; 96 #endif 97 case 'f': 98 fastlogin = 1; 99 break; 100 case '-': 101 case 'l': 102 asme = 0; 103 asthem = 1; 104 break; 105 case 'm': 106 asme = 1; 107 asthem = 0; 108 break; 109 case '?': 110 default: 111 (void)fprintf(stderr, "usage: su [%s] [login]\n", 112 ARGSTR); 113 exit(1); 114 } 115 argv += optind; 116 117 errno = 0; 118 prio = getpriority(PRIO_PROCESS, 0); 119 if (errno) 120 prio = 0; 121 (void)setpriority(PRIO_PROCESS, 0, -2); 122 openlog("su", LOG_CONS, 0); 123 124 /* get current login name and shell */ 125 ruid = getuid(); 126 username = getlogin(); 127 if (username == NULL || (pwd = getpwnam(username)) == NULL || 128 pwd->pw_uid != ruid) 129 pwd = getpwuid(ruid); 130 if (pwd == NULL) { 131 fprintf(stderr, "su: who are you?\n"); 132 exit(1); 133 } 134 username = strdup(pwd->pw_name); 135 if (asme) 136 if (pwd->pw_shell && *pwd->pw_shell) 137 shell = strcpy(shellbuf, pwd->pw_shell); 138 else { 139 shell = _PATH_BSHELL; 140 iscsh = NO; 141 } 142 143 /* get target login information, default to root */ 144 user = *argv ? *argv : "root"; 145 np = *argv ? argv : argv-1; 146 147 if ((pwd = getpwnam(user)) == NULL) { 148 fprintf(stderr, "su: unknown login %s\n", user); 149 exit(1); 150 } 151 152 if (ruid) { 153 #ifdef KERBEROS 154 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 155 #endif 156 { 157 /* only allow those in group zero to su to root. */ 158 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))) 159 for (g = gr->gr_mem;; ++g) { 160 if (!*g) { 161 (void)fprintf(stderr, 162 "su: you are not in the correct group to su %s.\n", 163 user); 164 exit(1); 165 } 166 if (!strcmp(username, *g)) 167 break; 168 } 169 /* if target requires a password, verify it */ 170 if (*pwd->pw_passwd) { 171 p = getpass("Password:"); 172 #ifdef SKEY 173 if (strcasecmp(p, "s/key") == 0) { 174 if (skey_haskey(user)) { 175 fprintf(stderr, "Sorry, you have no s/key.\n"); 176 exit(1); 177 } else { 178 if (skey_authenticate(user)) { 179 goto badlogin; 180 } 181 } 182 183 } else 184 #endif 185 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 186 badlogin: 187 fprintf(stderr, "Sorry\n"); 188 syslog(LOG_AUTH|LOG_WARNING, 189 "BAD SU %s to %s%s", username, 190 user, ontty()); 191 exit(1); 192 } 193 } 194 } 195 } 196 197 if (asme) { 198 /* if asme and non-standard target shell, must be root */ 199 if (!chshell(pwd->pw_shell) && ruid) { 200 (void)fprintf(stderr, 201 "su: permission denied (shell).\n"); 202 exit(1); 203 } 204 } else if (pwd->pw_shell && *pwd->pw_shell) { 205 shell = pwd->pw_shell; 206 iscsh = UNSET; 207 } else { 208 shell = _PATH_BSHELL; 209 iscsh = NO; 210 } 211 212 if (p = rindex(shell, '/')) 213 avshell = p+1; 214 else 215 avshell = shell; 216 217 /* if we're forking a csh, we want to slightly muck the args */ 218 if (iscsh == UNSET) 219 iscsh = strcmp(avshell, "csh") ? NO : YES; 220 221 /* set permissions */ 222 if (setgid(pwd->pw_gid) < 0) { 223 perror("su: setgid"); 224 exit(1); 225 } 226 if (initgroups(user, pwd->pw_gid)) { 227 (void)fprintf(stderr, "su: initgroups failed.\n"); 228 exit(1); 229 } 230 if (setuid(pwd->pw_uid) < 0) { 231 perror("su: setuid"); 232 exit(1); 233 } 234 235 if (!asme) { 236 if (asthem) { 237 p = getenv("TERM"); 238 cleanenv[0] = NULL; 239 environ = cleanenv; 240 (void)setenv("PATH", _PATH_DEFPATH, 1); 241 (void)setenv("TERM", p, 1); 242 if (chdir(pwd->pw_dir) < 0) { 243 fprintf(stderr, "su: no directory\n"); 244 exit(1); 245 } 246 } 247 if (asthem || pwd->pw_uid) 248 (void)setenv("USER", pwd->pw_name, 1); 249 (void)setenv("HOME", pwd->pw_dir, 1); 250 (void)setenv("SHELL", shell, 1); 251 } 252 253 if (iscsh == YES) { 254 if (fastlogin) 255 *np-- = "-f"; 256 if (asme) 257 *np-- = "-m"; 258 } 259 260 if (asthem) { 261 avshellbuf[0] = '-'; 262 strcpy(avshellbuf+1, avshell); 263 avshell = avshellbuf; 264 } else if (iscsh == YES) { 265 /* csh strips the first character... */ 266 avshellbuf[0] = '_'; 267 strcpy(avshellbuf+1, avshell); 268 avshell = avshellbuf; 269 } 270 271 *np = avshell; 272 273 if (ruid != 0) 274 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 275 username, user, ontty()); 276 277 (void)setpriority(PRIO_PROCESS, 0, prio); 278 279 execv(shell, np); 280 (void)fprintf(stderr, "su: %s not found.\n", shell); 281 exit(1); 282 } 283 284 int 285 chshell(sh) 286 char *sh; 287 { 288 register char *cp; 289 char *getusershell(); 290 291 while ((cp = getusershell()) != NULL) 292 if (!strcmp(cp, sh)) 293 return (1); 294 return (0); 295 } 296 297 char * 298 ontty() 299 { 300 char *p, *ttyname(); 301 static char buf[MAXPATHLEN + 4]; 302 303 buf[0] = 0; 304 if (p = ttyname(STDERR_FILENO)) 305 sprintf(buf, " on %s", p); 306 return (buf); 307 } 308 309 #ifdef KERBEROS 310 kerberos(username, user, uid) 311 char *username, *user; 312 int uid; 313 { 314 extern char *krb_err_txt[]; 315 KTEXT_ST ticket; 316 AUTH_DAT authdata; 317 struct hostent *hp; 318 register char *p; 319 int kerno; 320 u_long faddr; 321 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 322 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 323 char *ontty(), *krb_get_phost(); 324 325 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 326 return (1); 327 if (koktologin(username, lrealm, user) && !uid) { 328 (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user); 329 return (1); 330 } 331 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 332 333 (void)setenv("KRBTKFILE", krbtkfile, 1); 334 (void)krb_set_tkt_string(krbtkfile); 335 /* 336 * Set real as well as effective ID to 0 for the moment, 337 * to make the kerberos library do the right thing. 338 */ 339 if (setuid(0) < 0) { 340 perror("su: setuid"); 341 return (1); 342 } 343 344 /* 345 * Little trick here -- if we are su'ing to root, 346 * we need to get a ticket for "xxx.root", where xxx represents 347 * the name of the person su'ing. Otherwise (non-root case), 348 * we need to get a ticket for "yyy.", where yyy represents 349 * the name of the person being su'd to, and the instance is null 350 * 351 * We should have a way to set the ticket lifetime, 352 * with a system default for root. 353 */ 354 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 355 (uid == 0 ? "root" : ""), lrealm, 356 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 357 358 if (kerno != KSUCCESS) { 359 if (kerno == KDC_PR_UNKNOWN) { 360 fprintf(stderr, "principal unknown: %s.%s@%s\n", 361 (uid == 0 ? username : user), 362 (uid == 0 ? "root" : ""), lrealm); 363 return (1); 364 } 365 (void)fprintf(stderr, "su: unable to su: %s\n", 366 krb_err_txt[kerno]); 367 syslog(LOG_NOTICE|LOG_AUTH, 368 "BAD Kerberos SU: %s to %s%s: %s", 369 username, user, ontty(), krb_err_txt[kerno]); 370 return (1); 371 } 372 373 if (chown(krbtkfile, uid, -1) < 0) { 374 perror("su: chown:"); 375 (void)unlink(krbtkfile); 376 return (1); 377 } 378 379 (void)setpriority(PRIO_PROCESS, 0, -2); 380 381 if (gethostname(hostname, sizeof(hostname)) == -1) { 382 perror("su: gethostname"); 383 dest_tkt(); 384 return (1); 385 } 386 387 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 388 savehost[sizeof(savehost) - 1] = '\0'; 389 390 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 391 392 if (kerno == KDC_PR_UNKNOWN) { 393 (void)fprintf(stderr, "Warning: TGT not verified.\n"); 394 syslog(LOG_NOTICE|LOG_AUTH, 395 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 396 username, user, ontty(), krb_err_txt[kerno], 397 "rcmd", savehost); 398 } else if (kerno != KSUCCESS) { 399 (void)fprintf(stderr, "Unable to use TGT: %s\n", 400 krb_err_txt[kerno]); 401 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 402 username, user, ontty(), krb_err_txt[kerno]); 403 dest_tkt(); 404 return (1); 405 } else { 406 if (!(hp = gethostbyname(hostname))) { 407 (void)fprintf(stderr, "su: can't get addr of %s\n", 408 hostname); 409 dest_tkt(); 410 return (1); 411 } 412 (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr)); 413 414 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 415 &authdata, "")) != KSUCCESS) { 416 (void)fprintf(stderr, 417 "su: unable to verify rcmd ticket: %s\n", 418 krb_err_txt[kerno]); 419 syslog(LOG_NOTICE|LOG_AUTH, 420 "failed su: %s to %s%s: %s", username, 421 user, ontty(), krb_err_txt[kerno]); 422 dest_tkt(); 423 return (1); 424 } 425 } 426 return (0); 427 } 428 429 koktologin(name, realm, toname) 430 char *name, *realm, *toname; 431 { 432 register AUTH_DAT *kdata; 433 AUTH_DAT kdata_st; 434 435 kdata = &kdata_st; 436 bzero((caddr_t) kdata, sizeof(*kdata)); 437 (void)strcpy(kdata->pname, name); 438 (void)strcpy(kdata->pinst, 439 ((strcmp(toname, "root") == 0) ? "root" : "")); 440 (void)strcpy(kdata->prealm, realm); 441 return (kuserok(kdata, toname)); 442 } 443 #endif 444