su.c revision 1.4
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[] = "@(#)su.c 5.26 (Berkeley) 7/6/91"; 42 #endif /* not lint */ 43 44 #include <sys/param.h> 45 #include <sys/time.h> 46 #include <sys/resource.h> 47 #include <syslog.h> 48 #include <stdio.h> 49 #include <pwd.h> 50 #include <grp.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <paths.h> 54 55 #ifdef KERBEROS 56 #include <kerberosIV/des.h> 57 #include <kerberosIV/krb.h> 58 #include <netdb.h> 59 60 #define ARGSTR "-Kflm" 61 62 int use_kerberos = 1; 63 #else 64 #define ARGSTR "-flm" 65 #endif 66 67 extern char *crypt(); 68 69 main(argc, argv) 70 int argc; 71 char **argv; 72 { 73 extern char **environ; 74 extern int errno, optind; 75 register struct passwd *pwd; 76 register char *p, **g; 77 struct group *gr; 78 uid_t ruid, getuid(); 79 int asme, ch, asthem, fastlogin, prio; 80 enum { UNSET, YES, NO } iscsh = UNSET; 81 char *user, *shell, *username, *cleanenv[2], **np; 82 char shellbuf[MAXPATHLEN]; 83 char *getpass(), *getenv(), *getlogin(), *ontty(); 84 85 asme = asthem = fastlogin = 0; 86 while ((ch = getopt(argc, argv, ARGSTR)) != EOF) 87 switch((char)ch) { 88 #ifdef KERBEROS 89 case 'K': 90 use_kerberos = 0; 91 break; 92 #endif 93 case 'f': 94 fastlogin = 1; 95 break; 96 case '-': 97 case 'l': 98 asme = 0; 99 asthem = 1; 100 break; 101 case 'm': 102 asme = 1; 103 asthem = 0; 104 break; 105 case '?': 106 default: 107 (void)fprintf(stderr, "usage: su [%s] [login]\n", 108 ARGSTR); 109 exit(1); 110 } 111 argv += optind; 112 113 errno = 0; 114 prio = getpriority(PRIO_PROCESS, 0); 115 if (errno) 116 prio = 0; 117 (void)setpriority(PRIO_PROCESS, 0, -2); 118 openlog("su", LOG_CONS, 0); 119 120 /* get current login name and shell */ 121 ruid = getuid(); 122 username = getlogin(); 123 if (username == NULL || (pwd = getpwnam(username)) == NULL || 124 pwd->pw_uid != ruid) 125 pwd = getpwuid(ruid); 126 if (pwd == NULL) { 127 fprintf(stderr, "su: who are you?\n"); 128 exit(1); 129 } 130 username = strdup(pwd->pw_name); 131 if (asme) 132 if (pwd->pw_shell && *pwd->pw_shell) 133 shell = strcpy(shellbuf, pwd->pw_shell); 134 else { 135 shell = _PATH_BSHELL; 136 iscsh = NO; 137 } 138 139 /* get target login information, default to root */ 140 user = *argv ? *argv : "root"; 141 np = *argv ? argv : argv-1; 142 143 if ((pwd = getpwnam(user)) == NULL) { 144 fprintf(stderr, "su: unknown login %s\n", user); 145 exit(1); 146 } 147 148 if (ruid) { 149 #ifdef KERBEROS 150 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 151 #endif 152 { 153 /* only allow those in group zero to su to root. */ 154 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))) 155 for (g = gr->gr_mem;; ++g) { 156 if (!*g) { 157 (void)fprintf(stderr, 158 "su: you are not in the correct group to su %s.\n", 159 user); 160 exit(1); 161 } 162 if (!strcmp(username, *g)) 163 break; 164 } 165 /* if target requires a password, verify it */ 166 if (*pwd->pw_passwd) { 167 p = getpass("Password:"); 168 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 169 fprintf(stderr, "Sorry\n"); 170 syslog(LOG_AUTH|LOG_WARNING, 171 "BAD SU %s to %s%s", username, 172 user, ontty()); 173 exit(1); 174 } 175 } 176 } 177 } 178 179 if (asme) { 180 /* if asme and non-standard target shell, must be root */ 181 if (!chshell(pwd->pw_shell) && ruid) { 182 (void)fprintf(stderr, 183 "su: permission denied (shell).\n"); 184 exit(1); 185 } 186 } else if (pwd->pw_shell && *pwd->pw_shell) { 187 shell = pwd->pw_shell; 188 iscsh = UNSET; 189 } else { 190 shell = _PATH_BSHELL; 191 iscsh = NO; 192 } 193 194 /* if we're forking a csh, we want to slightly muck the args */ 195 if (iscsh == UNSET) { 196 if (p = rindex(shell, '/')) 197 ++p; 198 else 199 p = shell; 200 iscsh = strcmp(p, "csh") ? NO : YES; 201 } 202 203 /* set permissions */ 204 if (setgid(pwd->pw_gid) < 0) { 205 perror("su: setgid"); 206 exit(1); 207 } 208 if (initgroups(user, pwd->pw_gid)) { 209 (void)fprintf(stderr, "su: initgroups failed.\n"); 210 exit(1); 211 } 212 if (setuid(pwd->pw_uid) < 0) { 213 perror("su: setuid"); 214 exit(1); 215 } 216 217 if (!asme) { 218 if (asthem) { 219 p = getenv("TERM"); 220 cleanenv[0] = _PATH_DEFPATH; 221 cleanenv[1] = NULL; 222 environ = cleanenv; 223 (void)setenv("TERM", p, 1); 224 if (chdir(pwd->pw_dir) < 0) { 225 fprintf(stderr, "su: no directory\n"); 226 exit(1); 227 } 228 } 229 if (asthem || pwd->pw_uid) { 230 (void)setenv("LOGNAME", pwd->pw_name, 1); 231 (void)setenv("USER", pwd->pw_name, 1); 232 } 233 (void)setenv("HOME", pwd->pw_dir, 1); 234 (void)setenv("SHELL", shell, 1); 235 } 236 237 if (iscsh == YES) { 238 if (fastlogin) 239 *np-- = "-f"; 240 if (asme) 241 *np-- = "-m"; 242 } 243 244 /* csh strips the first character... */ 245 *np = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 246 247 if (ruid != 0) 248 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 249 username, user, ontty()); 250 251 (void)setpriority(PRIO_PROCESS, 0, prio); 252 253 execv(shell, np); 254 (void)fprintf(stderr, "su: %s not found.\n", shell); 255 exit(1); 256 } 257 258 chshell(sh) 259 char *sh; 260 { 261 register char *cp; 262 char *getusershell(); 263 264 while ((cp = getusershell()) != NULL) 265 if (!strcmp(cp, sh)) 266 return (1); 267 return (0); 268 } 269 270 char * 271 ontty() 272 { 273 char *p, *ttyname(); 274 static char buf[MAXPATHLEN + 4]; 275 276 buf[0] = 0; 277 if (p = ttyname(STDERR_FILENO)) 278 sprintf(buf, " on %s", p); 279 return (buf); 280 } 281 282 #ifdef KERBEROS 283 kerberos(username, user, uid) 284 char *username, *user; 285 int uid; 286 { 287 extern char *krb_err_txt[]; 288 KTEXT_ST ticket; 289 AUTH_DAT authdata; 290 struct hostent *hp; 291 register char *p; 292 int kerno; 293 u_long faddr; 294 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 295 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 296 char *ontty(), *krb_get_phost(); 297 298 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 299 return (1); 300 if (koktologin(username, lrealm, user) && !uid) { 301 (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user); 302 return (1); 303 } 304 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 305 306 (void)setenv("KRBTKFILE", krbtkfile, 1); 307 (void)krb_set_tkt_string(krbtkfile); 308 /* 309 * Set real as well as effective ID to 0 for the moment, 310 * to make the kerberos library do the right thing. 311 */ 312 if (setuid(0) < 0) { 313 perror("su: setuid"); 314 return (1); 315 } 316 317 /* 318 * Little trick here -- if we are su'ing to root, 319 * we need to get a ticket for "xxx.root", where xxx represents 320 * the name of the person su'ing. Otherwise (non-root case), 321 * we need to get a ticket for "yyy.", where yyy represents 322 * the name of the person being su'd to, and the instance is null 323 * 324 * We should have a way to set the ticket lifetime, 325 * with a system default for root. 326 */ 327 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 328 (uid == 0 ? "root" : ""), lrealm, 329 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 330 331 if (kerno != KSUCCESS) { 332 if (kerno == KDC_PR_UNKNOWN) { 333 fprintf(stderr, "principal unknown: %s.%s@%s\n", 334 (uid == 0 ? username : user), 335 (uid == 0 ? "root" : ""), lrealm); 336 return (1); 337 } 338 (void)fprintf(stderr, "su: unable to su: %s\n", 339 krb_err_txt[kerno]); 340 syslog(LOG_NOTICE|LOG_AUTH, 341 "BAD Kerberos SU: %s to %s%s: %s", 342 username, user, ontty(), krb_err_txt[kerno]); 343 return (1); 344 } 345 346 if (chown(krbtkfile, uid, -1) < 0) { 347 perror("su: chown:"); 348 (void)unlink(krbtkfile); 349 return (1); 350 } 351 352 (void)setpriority(PRIO_PROCESS, 0, -2); 353 354 if (gethostname(hostname, sizeof(hostname)) == -1) { 355 perror("su: gethostname"); 356 dest_tkt(); 357 return (1); 358 } 359 360 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 361 savehost[sizeof(savehost) - 1] = '\0'; 362 363 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 364 365 if (kerno == KDC_PR_UNKNOWN) { 366 (void)fprintf(stderr, "Warning: TGT not verified.\n"); 367 syslog(LOG_NOTICE|LOG_AUTH, 368 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 369 username, user, ontty(), krb_err_txt[kerno], 370 "rcmd", savehost); 371 } else if (kerno != KSUCCESS) { 372 (void)fprintf(stderr, "Unable to use TGT: %s\n", 373 krb_err_txt[kerno]); 374 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 375 username, user, ontty(), krb_err_txt[kerno]); 376 dest_tkt(); 377 return (1); 378 } else { 379 if (!(hp = gethostbyname(hostname))) { 380 (void)fprintf(stderr, "su: can't get addr of %s\n", 381 hostname); 382 dest_tkt(); 383 return (1); 384 } 385 (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr)); 386 387 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 388 &authdata, "")) != KSUCCESS) { 389 (void)fprintf(stderr, 390 "su: unable to verify rcmd ticket: %s\n", 391 krb_err_txt[kerno]); 392 syslog(LOG_NOTICE|LOG_AUTH, 393 "failed su: %s to %s%s: %s", username, 394 user, ontty(), krb_err_txt[kerno]); 395 dest_tkt(); 396 return (1); 397 } 398 } 399 return (0); 400 } 401 402 koktologin(name, realm, toname) 403 char *name, *realm, *toname; 404 { 405 register AUTH_DAT *kdata; 406 AUTH_DAT kdata_st; 407 408 kdata = &kdata_st; 409 bzero((caddr_t) kdata, sizeof(*kdata)); 410 (void)strcpy(kdata->pname, name); 411 (void)strcpy(kdata->pinst, 412 ((strcmp(toname, "root") == 0) ? "root" : "")); 413 (void)strcpy(kdata->prealm, realm); 414 return (kuserok(kdata, toname)); 415 } 416 #endif 417
Indexes created Mon Oct 27 08:10:08 GMT 2025