su.c revision 1.7
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 1.7 1993/08/27 22:30:44 jtc 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, *username, *cleanenv[2], **np; 86 char shellbuf[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 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 173 fprintf(stderr, "Sorry\n"); 174 syslog(LOG_AUTH|LOG_WARNING, 175 "BAD SU %s to %s%s", username, 176 user, ontty()); 177 exit(1); 178 } 179 } 180 } 181 } 182 183 if (asme) { 184 /* if asme and non-standard target shell, must be root */ 185 if (!chshell(pwd->pw_shell) && ruid) { 186 (void)fprintf(stderr, 187 "su: permission denied (shell).\n"); 188 exit(1); 189 } 190 } else if (pwd->pw_shell && *pwd->pw_shell) { 191 shell = pwd->pw_shell; 192 iscsh = UNSET; 193 } else { 194 shell = _PATH_BSHELL; 195 iscsh = NO; 196 } 197 198 /* if we're forking a csh, we want to slightly muck the args */ 199 if (iscsh == UNSET) { 200 if (p = rindex(shell, '/')) 201 ++p; 202 else 203 p = shell; 204 iscsh = strcmp(p, "csh") ? NO : YES; 205 } 206 207 /* set permissions */ 208 if (setgid(pwd->pw_gid) < 0) { 209 perror("su: setgid"); 210 exit(1); 211 } 212 if (initgroups(user, pwd->pw_gid)) { 213 (void)fprintf(stderr, "su: initgroups failed.\n"); 214 exit(1); 215 } 216 if (setuid(pwd->pw_uid) < 0) { 217 perror("su: setuid"); 218 exit(1); 219 } 220 221 if (!asme) { 222 if (asthem) { 223 p = getenv("TERM"); 224 cleanenv[0] = _PATH_DEFPATH; 225 cleanenv[1] = NULL; 226 environ = cleanenv; 227 (void)setenv("TERM", p, 1); 228 if (chdir(pwd->pw_dir) < 0) { 229 fprintf(stderr, "su: no directory\n"); 230 exit(1); 231 } 232 } 233 if (asthem || pwd->pw_uid) 234 (void)setenv("USER", pwd->pw_name, 1); 235 (void)setenv("HOME", pwd->pw_dir, 1); 236 (void)setenv("SHELL", shell, 1); 237 } 238 239 if (iscsh == YES) { 240 if (fastlogin) 241 *np-- = "-f"; 242 if (asme) 243 *np-- = "-m"; 244 } 245 246 /* csh strips the first character... */ 247 *np = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 248 249 if (ruid != 0) 250 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 251 username, user, ontty()); 252 253 (void)setpriority(PRIO_PROCESS, 0, prio); 254 255 execv(shell, np); 256 (void)fprintf(stderr, "su: %s not found.\n", shell); 257 exit(1); 258 } 259 260 int 261 chshell(sh) 262 char *sh; 263 { 264 register char *cp; 265 char *getusershell(); 266 267 while ((cp = getusershell()) != NULL) 268 if (!strcmp(cp, sh)) 269 return (1); 270 return (0); 271 } 272 273 char * 274 ontty() 275 { 276 char *p, *ttyname(); 277 static char buf[MAXPATHLEN + 4]; 278 279 buf[0] = 0; 280 if (p = ttyname(STDERR_FILENO)) 281 sprintf(buf, " on %s", p); 282 return (buf); 283 } 284 285 #ifdef KERBEROS 286 kerberos(username, user, uid) 287 char *username, *user; 288 int uid; 289 { 290 extern char *krb_err_txt[]; 291 KTEXT_ST ticket; 292 AUTH_DAT authdata; 293 struct hostent *hp; 294 register char *p; 295 int kerno; 296 u_long faddr; 297 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 298 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 299 char *ontty(), *krb_get_phost(); 300 301 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 302 return (1); 303 if (koktologin(username, lrealm, user) && !uid) { 304 (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user); 305 return (1); 306 } 307 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 308 309 (void)setenv("KRBTKFILE", krbtkfile, 1); 310 (void)krb_set_tkt_string(krbtkfile); 311 /* 312 * Set real as well as effective ID to 0 for the moment, 313 * to make the kerberos library do the right thing. 314 */ 315 if (setuid(0) < 0) { 316 perror("su: setuid"); 317 return (1); 318 } 319 320 /* 321 * Little trick here -- if we are su'ing to root, 322 * we need to get a ticket for "xxx.root", where xxx represents 323 * the name of the person su'ing. Otherwise (non-root case), 324 * we need to get a ticket for "yyy.", where yyy represents 325 * the name of the person being su'd to, and the instance is null 326 * 327 * We should have a way to set the ticket lifetime, 328 * with a system default for root. 329 */ 330 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 331 (uid == 0 ? "root" : ""), lrealm, 332 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 333 334 if (kerno != KSUCCESS) { 335 if (kerno == KDC_PR_UNKNOWN) { 336 fprintf(stderr, "principal unknown: %s.%s@%s\n", 337 (uid == 0 ? username : user), 338 (uid == 0 ? "root" : ""), lrealm); 339 return (1); 340 } 341 (void)fprintf(stderr, "su: unable to su: %s\n", 342 krb_err_txt[kerno]); 343 syslog(LOG_NOTICE|LOG_AUTH, 344 "BAD Kerberos SU: %s to %s%s: %s", 345 username, user, ontty(), krb_err_txt[kerno]); 346 return (1); 347 } 348 349 if (chown(krbtkfile, uid, -1) < 0) { 350 perror("su: chown:"); 351 (void)unlink(krbtkfile); 352 return (1); 353 } 354 355 (void)setpriority(PRIO_PROCESS, 0, -2); 356 357 if (gethostname(hostname, sizeof(hostname)) == -1) { 358 perror("su: gethostname"); 359 dest_tkt(); 360 return (1); 361 } 362 363 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 364 savehost[sizeof(savehost) - 1] = '\0'; 365 366 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 367 368 if (kerno == KDC_PR_UNKNOWN) { 369 (void)fprintf(stderr, "Warning: TGT not verified.\n"); 370 syslog(LOG_NOTICE|LOG_AUTH, 371 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 372 username, user, ontty(), krb_err_txt[kerno], 373 "rcmd", savehost); 374 } else if (kerno != KSUCCESS) { 375 (void)fprintf(stderr, "Unable to use TGT: %s\n", 376 krb_err_txt[kerno]); 377 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 378 username, user, ontty(), krb_err_txt[kerno]); 379 dest_tkt(); 380 return (1); 381 } else { 382 if (!(hp = gethostbyname(hostname))) { 383 (void)fprintf(stderr, "su: can't get addr of %s\n", 384 hostname); 385 dest_tkt(); 386 return (1); 387 } 388 (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr)); 389 390 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 391 &authdata, "")) != KSUCCESS) { 392 (void)fprintf(stderr, 393 "su: unable to verify rcmd ticket: %s\n", 394 krb_err_txt[kerno]); 395 syslog(LOG_NOTICE|LOG_AUTH, 396 "failed su: %s to %s%s: %s", username, 397 user, ontty(), krb_err_txt[kerno]); 398 dest_tkt(); 399 return (1); 400 } 401 } 402 return (0); 403 } 404 405 koktologin(name, realm, toname) 406 char *name, *realm, *toname; 407 { 408 register AUTH_DAT *kdata; 409 AUTH_DAT kdata_st; 410 411 kdata = &kdata_st; 412 bzero((caddr_t) kdata, sizeof(*kdata)); 413 (void)strcpy(kdata->pname, name); 414 (void)strcpy(kdata->pinst, 415 ((strcmp(toname, "root") == 0) ? "root" : "")); 416 (void)strcpy(kdata->prealm, realm); 417 return (kuserok(kdata, toname)); 418 } 419 #endif 420
Indexes created Fri Sep 26 08:10:20 GMT 2025