su.c revision 1.13
1 /* $NetBSD: su.c,v 1.13 1997/01/09 11:43:07 tls Exp $ */ 2 3 /* 4 * Copyright (c) 1988 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef lint 37 char copyright[] = 38 "@(#) Copyright (c) 1988 The Regents of the University of California.\n\ 39 All rights reserved.\n"; 40 #endif /* not lint */ 41 42 #ifndef lint 43 #if 0 44 static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/ 45 #else 46 static char rcsid[] = "$NetBSD: su.c,v 1.13 1997/01/09 11:43:07 tls Exp $"; 47 #endif 48 #endif /* not lint */ 49 50 #include <sys/param.h> 51 #include <sys/time.h> 52 #include <sys/resource.h> 53 #include <syslog.h> 54 #include <stdio.h> 55 #include <err.h> 56 #include <errno.h> 57 #include <stdlib.h> 58 #include <pwd.h> 59 #include <grp.h> 60 #include <string.h> 61 #include <unistd.h> 62 #include <paths.h> 63 64 #ifdef KERBEROS 65 #include <kerberosIV/des.h> 66 #include <kerberosIV/krb.h> 67 #include <netdb.h> 68 69 #define ARGSTR "-Kflm" 70 71 int use_kerberos = 1; 72 73 static int kerberos __P((char *, char *, int)); 74 static int koktologin __P((char *, char *, char *)); 75 76 #else 77 #define ARGSTR "-flm" 78 #endif 79 80 81 int main __P((int, char **)); 82 83 static int chshell __P((char *)); 84 static char *ontty __P((void)); 85 86 87 int 88 main(argc, argv) 89 int argc; 90 char **argv; 91 { 92 extern char *__progname; 93 extern char **environ; 94 struct passwd *pwd; 95 char *p, **g; 96 struct group *gr; 97 uid_t ruid; 98 int asme, ch, asthem, fastlogin, prio; 99 enum { UNSET, YES, NO } iscsh = UNSET; 100 char *user, *shell, *avshell, *username, *cleanenv[10], **np; 101 char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN]; 102 103 asme = asthem = fastlogin = 0; 104 while ((ch = getopt(argc, argv, ARGSTR)) != EOF) 105 switch((char)ch) { 106 #ifdef KERBEROS 107 case 'K': 108 use_kerberos = 0; 109 break; 110 #endif 111 case 'f': 112 fastlogin = 1; 113 break; 114 case '-': 115 case 'l': 116 asme = 0; 117 asthem = 1; 118 break; 119 case 'm': 120 asme = 1; 121 asthem = 0; 122 break; 123 case '?': 124 default: 125 (void)fprintf(stderr, 126 "Usage: %s [%s] [login [shell arguments]]\n", 127 __progname, ARGSTR); 128 exit(1); 129 } 130 argv += optind; 131 132 errno = 0; 133 prio = getpriority(PRIO_PROCESS, 0); 134 if (errno) 135 prio = 0; 136 (void)setpriority(PRIO_PROCESS, 0, -2); 137 openlog("su", LOG_CONS, 0); 138 139 /* get current login name and shell */ 140 ruid = getuid(); 141 username = getlogin(); 142 if (username == NULL || (pwd = getpwnam(username)) == NULL || 143 pwd->pw_uid != ruid) 144 pwd = getpwuid(ruid); 145 if (pwd == NULL) { 146 errx(1, "who are you?"); 147 } 148 username = strdup(pwd->pw_name); 149 if (asme) 150 if (pwd->pw_shell && *pwd->pw_shell) 151 shell = strcpy(shellbuf, pwd->pw_shell); 152 else { 153 shell = _PATH_BSHELL; 154 iscsh = NO; 155 } 156 157 /* get target login information, default to root */ 158 user = *argv ? *argv : "root"; 159 np = *argv ? argv : argv-1; 160 161 if ((pwd = getpwnam(user)) == NULL) { 162 errx(1, "unknown login %s", user); 163 } 164 165 if (ruid) { 166 #ifdef KERBEROS 167 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 168 #endif 169 { 170 /* only allow those in group zero to su to root. */ 171 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))) 172 for (g = gr->gr_mem;; ++g) { 173 if (!*g) 174 errx(1, 175 "you are not in the correct group to su %s.", 176 user); 177 if (!strcmp(username, *g)) 178 break; 179 } 180 /* if target requires a password, verify it */ 181 if (*pwd->pw_passwd) { 182 p = getpass("Password:"); 183 #ifdef SKEY 184 if (strcasecmp(p, "s/key") == 0) { 185 if (skey_haskey(user)) 186 errx(1, "Sorry, you have no s/key."); 187 else { 188 if (skey_authenticate(user)) { 189 goto badlogin; 190 } 191 } 192 193 } else 194 #endif 195 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 196 badlogin: 197 fprintf(stderr, "Sorry\n"); 198 syslog(LOG_AUTH|LOG_WARNING, 199 "BAD SU %s to %s%s", username, 200 user, ontty()); 201 exit(1); 202 } 203 } 204 } 205 } 206 207 if (asme) { 208 /* if asme and non-standard target shell, must be root */ 209 if (!chshell(pwd->pw_shell) && ruid) 210 errx(1,"permission denied (shell)."); 211 } else if (pwd->pw_shell && *pwd->pw_shell) { 212 shell = pwd->pw_shell; 213 iscsh = UNSET; 214 } else { 215 shell = _PATH_BSHELL; 216 iscsh = NO; 217 } 218 219 if (p = strrchr(shell, '/')) 220 avshell = p+1; 221 else 222 avshell = shell; 223 224 /* if we're forking a csh, we want to slightly muck the args */ 225 if (iscsh == UNSET) 226 iscsh = strstr(avshell, "csh") ? YES : NO; 227 228 /* set permissions */ 229 if (setgid(pwd->pw_gid) < 0) 230 err(1, "setgid"); 231 if (initgroups(user, pwd->pw_gid)) 232 errx(1, "initgroups failed"); 233 if (setuid(pwd->pw_uid) < 0) 234 err(1, "setuid"); 235 236 if (!asme) { 237 if (asthem) { 238 p = getenv("TERM"); 239 cleanenv[0] = NULL; 240 environ = cleanenv; 241 (void)setenv("PATH", _PATH_DEFPATH, 1); 242 if (p) 243 (void)setenv("TERM", p, 1); 244 if (chdir(pwd->pw_dir) < 0) 245 errx(1, "no directory"); 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 *np = avshell; 271 272 if (ruid != 0) 273 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 274 username, user, ontty()); 275 276 (void)setpriority(PRIO_PROCESS, 0, prio); 277 278 execv(shell, np); 279 err(1, "%s", shell); 280 } 281 282 static int 283 chshell(sh) 284 char *sh; 285 { 286 char *cp; 287 char *getusershell(); 288 289 while ((cp = getusershell()) != NULL) 290 if (!strcmp(cp, sh)) 291 return (1); 292 return (0); 293 } 294 295 static char * 296 ontty() 297 { 298 char *p, *ttyname(); 299 static char buf[MAXPATHLEN + 4]; 300 301 buf[0] = 0; 302 if (p = ttyname(STDERR_FILENO)) 303 sprintf(buf, " on %s", p); 304 return (buf); 305 } 306 307 #ifdef KERBEROS 308 static int 309 kerberos(username, user, uid) 310 char *username, *user; 311 int uid; 312 { 313 KTEXT_ST ticket; 314 AUTH_DAT authdata; 315 struct hostent *hp; 316 register char *p; 317 int kerno; 318 u_long faddr; 319 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 320 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 321 char *ontty(), *krb_get_phost(); 322 323 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 324 return (1); 325 if (koktologin(username, lrealm, user) && !uid) { 326 warnx("kerberos: not in %s's ACL.", user); 327 return (1); 328 } 329 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 330 331 (void)setenv("KRBTKFILE", krbtkfile, 1); 332 (void)krb_set_tkt_string(krbtkfile); 333 /* 334 * Set real as well as effective ID to 0 for the moment, 335 * to make the kerberos library do the right thing. 336 */ 337 if (setuid(0) < 0) { 338 warn("setuid"); 339 return (1); 340 } 341 342 /* 343 * Little trick here -- if we are su'ing to root, 344 * we need to get a ticket for "xxx.root", where xxx represents 345 * the name of the person su'ing. Otherwise (non-root case), 346 * we need to get a ticket for "yyy.", where yyy represents 347 * the name of the person being su'd to, and the instance is null 348 * 349 * We should have a way to set the ticket lifetime, 350 * with a system default for root. 351 */ 352 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 353 (uid == 0 ? "root" : ""), lrealm, 354 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 355 356 if (kerno != KSUCCESS) { 357 if (kerno == KDC_PR_UNKNOWN) { 358 warnx("kerberos: principal unknown: %s.%s@%s", 359 (uid == 0 ? username : user), 360 (uid == 0 ? "root" : ""), lrealm); 361 return (1); 362 } 363 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 364 syslog(LOG_NOTICE|LOG_AUTH, 365 "BAD Kerberos SU: %s to %s%s: %s", 366 username, user, ontty(), krb_err_txt[kerno]); 367 return (1); 368 } 369 370 if (chown(krbtkfile, uid, -1) < 0) { 371 warn("chown"); 372 (void)unlink(krbtkfile); 373 return (1); 374 } 375 376 (void)setpriority(PRIO_PROCESS, 0, -2); 377 378 if (gethostname(hostname, sizeof(hostname)) == -1) { 379 warn("gethostname"); 380 dest_tkt(); 381 return (1); 382 } 383 384 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 385 savehost[sizeof(savehost) - 1] = '\0'; 386 387 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 388 389 if (kerno == KDC_PR_UNKNOWN) { 390 warnx("Warning: TGT not verified."); 391 syslog(LOG_NOTICE|LOG_AUTH, 392 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 393 username, user, ontty(), krb_err_txt[kerno], 394 "rcmd", savehost); 395 } else if (kerno != KSUCCESS) { 396 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 397 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 398 username, user, ontty(), krb_err_txt[kerno]); 399 dest_tkt(); 400 return (1); 401 } else { 402 if (!(hp = gethostbyname(hostname))) { 403 warnx("can't get addr of %s", hostname); 404 dest_tkt(); 405 return (1); 406 } 407 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 408 409 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 410 &authdata, "")) != KSUCCESS) { 411 warnx("kerberos: unable to verify rcmd ticket: %s\n", 412 krb_err_txt[kerno]); 413 syslog(LOG_NOTICE|LOG_AUTH, 414 "failed su: %s to %s%s: %s", username, 415 user, ontty(), krb_err_txt[kerno]); 416 dest_tkt(); 417 return (1); 418 } 419 } 420 return (0); 421 } 422 423 static int 424 koktologin(name, realm, toname) 425 char *name, *realm, *toname; 426 { 427 register AUTH_DAT *kdata; 428 AUTH_DAT kdata_st; 429 430 kdata = &kdata_st; 431 memset((char *)kdata, 0, sizeof(*kdata)); 432 (void)strcpy(kdata->pname, name); 433 (void)strcpy(kdata->pinst, 434 ((strcmp(toname, "root") == 0) ? "root" : "")); 435 (void)strcpy(kdata->prealm, realm); 436 return (kuserok(kdata, toname)); 437 } 438 #endif 439
Indexes created Wed Sep 24 22:09:59 GMT 2025