su.c revision 1.5
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("USER", pwd->pw_name, 1); 231 (void)setenv("HOME", pwd->pw_dir, 1); 232 (void)setenv("SHELL", shell, 1); 233 } 234 235 if (iscsh == YES) { 236 if (fastlogin) 237 *np-- = "-f"; 238 if (asme) 239 *np-- = "-m"; 240 } 241 242 /* csh strips the first character... */ 243 *np = asthem ? "-su" : iscsh == YES ? "_su" : "su"; 244 245 if (ruid != 0) 246 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 247 username, user, ontty()); 248 249 (void)setpriority(PRIO_PROCESS, 0, prio); 250 251 execv(shell, np); 252 (void)fprintf(stderr, "su: %s not found.\n", shell); 253 exit(1); 254 } 255 256 chshell(sh) 257 char *sh; 258 { 259 register char *cp; 260 char *getusershell(); 261 262 while ((cp = getusershell()) != NULL) 263 if (!strcmp(cp, sh)) 264 return (1); 265 return (0); 266 } 267 268 char * 269 ontty() 270 { 271 char *p, *ttyname(); 272 static char buf[MAXPATHLEN + 4]; 273 274 buf[0] = 0; 275 if (p = ttyname(STDERR_FILENO)) 276 sprintf(buf, " on %s", p); 277 return (buf); 278 } 279 280 #ifdef KERBEROS 281 kerberos(username, user, uid) 282 char *username, *user; 283 int uid; 284 { 285 extern char *krb_err_txt[]; 286 KTEXT_ST ticket; 287 AUTH_DAT authdata; 288 struct hostent *hp; 289 register char *p; 290 int kerno; 291 u_long faddr; 292 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 293 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 294 char *ontty(), *krb_get_phost(); 295 296 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 297 return (1); 298 if (koktologin(username, lrealm, user) && !uid) { 299 (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user); 300 return (1); 301 } 302 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 303 304 (void)setenv("KRBTKFILE", krbtkfile, 1); 305 (void)krb_set_tkt_string(krbtkfile); 306 /* 307 * Set real as well as effective ID to 0 for the moment, 308 * to make the kerberos library do the right thing. 309 */ 310 if (setuid(0) < 0) { 311 perror("su: setuid"); 312 return (1); 313 } 314 315 /* 316 * Little trick here -- if we are su'ing to root, 317 * we need to get a ticket for "xxx.root", where xxx represents 318 * the name of the person su'ing. Otherwise (non-root case), 319 * we need to get a ticket for "yyy.", where yyy represents 320 * the name of the person being su'd to, and the instance is null 321 * 322 * We should have a way to set the ticket lifetime, 323 * with a system default for root. 324 */ 325 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 326 (uid == 0 ? "root" : ""), lrealm, 327 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 328 329 if (kerno != KSUCCESS) { 330 if (kerno == KDC_PR_UNKNOWN) { 331 fprintf(stderr, "principal unknown: %s.%s@%s\n", 332 (uid == 0 ? username : user), 333 (uid == 0 ? "root" : ""), lrealm); 334 return (1); 335 } 336 (void)fprintf(stderr, "su: unable to su: %s\n", 337 krb_err_txt[kerno]); 338 syslog(LOG_NOTICE|LOG_AUTH, 339 "BAD Kerberos SU: %s to %s%s: %s", 340 username, user, ontty(), krb_err_txt[kerno]); 341 return (1); 342 } 343 344 if (chown(krbtkfile, uid, -1) < 0) { 345 perror("su: chown:"); 346 (void)unlink(krbtkfile); 347 return (1); 348 } 349 350 (void)setpriority(PRIO_PROCESS, 0, -2); 351 352 if (gethostname(hostname, sizeof(hostname)) == -1) { 353 perror("su: gethostname"); 354 dest_tkt(); 355 return (1); 356 } 357 358 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 359 savehost[sizeof(savehost) - 1] = '\0'; 360 361 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 362 363 if (kerno == KDC_PR_UNKNOWN) { 364 (void)fprintf(stderr, "Warning: TGT not verified.\n"); 365 syslog(LOG_NOTICE|LOG_AUTH, 366 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 367 username, user, ontty(), krb_err_txt[kerno], 368 "rcmd", savehost); 369 } else if (kerno != KSUCCESS) { 370 (void)fprintf(stderr, "Unable to use TGT: %s\n", 371 krb_err_txt[kerno]); 372 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 373 username, user, ontty(), krb_err_txt[kerno]); 374 dest_tkt(); 375 return (1); 376 } else { 377 if (!(hp = gethostbyname(hostname))) { 378 (void)fprintf(stderr, "su: can't get addr of %s\n", 379 hostname); 380 dest_tkt(); 381 return (1); 382 } 383 (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr)); 384 385 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 386 &authdata, "")) != KSUCCESS) { 387 (void)fprintf(stderr, 388 "su: unable to verify rcmd ticket: %s\n", 389 krb_err_txt[kerno]); 390 syslog(LOG_NOTICE|LOG_AUTH, 391 "failed su: %s to %s%s: %s", username, 392 user, ontty(), krb_err_txt[kerno]); 393 dest_tkt(); 394 return (1); 395 } 396 } 397 return (0); 398 } 399 400 koktologin(name, realm, toname) 401 char *name, *realm, *toname; 402 { 403 register AUTH_DAT *kdata; 404 AUTH_DAT kdata_st; 405 406 kdata = &kdata_st; 407 bzero((caddr_t) kdata, sizeof(*kdata)); 408 (void)strcpy(kdata->pname, name); 409 (void)strcpy(kdata->pinst, 410 ((strcmp(toname, "root") == 0) ? "root" : "")); 411 (void)strcpy(kdata->prealm, realm); 412 return (kuserok(kdata, toname)); 413 } 414 #endif 415
Indexes created Sat Sep 27 14:09:57 GMT 2025