su.c revision 1.21
1 /* $NetBSD: su.c,v 1.21 1998/04/02 11:13:33 kleink 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 #include <sys/cdefs.h> 37 #ifndef lint 38 __COPYRIGHT( 39 "@(#) Copyright (c) 1988 The Regents of the University of California.\n\ 40 All rights reserved.\n"); 41 #endif /* not lint */ 42 43 #ifndef lint 44 #if 0 45 static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/ 46 #else 47 __RCSID("$NetBSD: su.c,v 1.21 1998/04/02 11:13:33 kleink Exp $"); 48 #endif 49 #endif /* not lint */ 50 51 #include <sys/param.h> 52 #include <sys/time.h> 53 #include <sys/resource.h> 54 #include <err.h> 55 #include <errno.h> 56 #include <grp.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <stdio.h> 60 #include <skey.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <syslog.h> 64 #include <time.h> 65 #include <tzfile.h> 66 #include <unistd.h> 67 68 #ifdef KERBEROS 69 #include <kerberosIV/des.h> 70 #include <kerberosIV/krb.h> 71 #include <netdb.h> 72 73 #define ARGSTR "-Kflm" 74 75 int use_kerberos = 1; 76 77 static int kerberos __P((char *, char *, int)); 78 static int koktologin __P((char *, char *, char *)); 79 80 #else 81 #define ARGSTR "-flm" 82 #endif 83 84 #ifndef SUGROUP 85 #define SUGROUP "wheel" 86 #endif 87 88 89 int main __P((int, char **)); 90 91 static int chshell __P((char *)); 92 static char *ontty __P((void)); 93 94 95 int 96 main(argc, argv) 97 int argc; 98 char **argv; 99 { 100 extern char *__progname; 101 extern char **environ; 102 struct passwd *pwd; 103 char *p; 104 struct group *gr; 105 struct timeval tp; 106 uid_t ruid; 107 int asme, ch, asthem, fastlogin, prio; 108 enum { UNSET, YES, NO } iscsh = UNSET; 109 char *user, *shell, *avshell, *username, *cleanenv[10], **np; 110 char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN]; 111 112 asme = asthem = fastlogin = 0; 113 shell = NULL; 114 while ((ch = getopt(argc, argv, ARGSTR)) != -1) 115 switch((char)ch) { 116 #ifdef KERBEROS 117 case 'K': 118 use_kerberos = 0; 119 break; 120 #endif 121 case 'f': 122 fastlogin = 1; 123 break; 124 case '-': 125 case 'l': 126 asme = 0; 127 asthem = 1; 128 break; 129 case 'm': 130 asme = 1; 131 asthem = 0; 132 break; 133 case '?': 134 default: 135 (void)fprintf(stderr, 136 "Usage: %s [%s] [login [shell arguments]]\n", 137 __progname, ARGSTR); 138 exit(1); 139 } 140 argv += optind; 141 142 errno = 0; 143 prio = getpriority(PRIO_PROCESS, 0); 144 if (errno) 145 prio = 0; 146 (void)setpriority(PRIO_PROCESS, 0, -2); 147 openlog("su", LOG_CONS, 0); 148 149 /* get current login name and shell */ 150 ruid = getuid(); 151 username = getlogin(); 152 if (username == NULL || (pwd = getpwnam(username)) == NULL || 153 pwd->pw_uid != ruid) 154 pwd = getpwuid(ruid); 155 if (pwd == NULL) { 156 errx(1, "who are you?"); 157 } 158 username = strdup(pwd->pw_name); 159 if (asme) 160 if (pwd->pw_shell && *pwd->pw_shell) 161 shell = strncpy(shellbuf, pwd->pw_shell, 162 sizeof(shellbuf) + 1); 163 else { 164 shell = _PATH_BSHELL; 165 iscsh = NO; 166 } 167 168 /* get target login information, default to root */ 169 user = *argv ? *argv : "root"; 170 np = *argv ? argv : argv-1; 171 172 if ((pwd = getpwnam(user)) == NULL) { 173 errx(1, "unknown login %s", user); 174 } 175 176 if (ruid) { 177 #ifdef KERBEROS 178 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 179 #endif 180 { 181 /* Only allow those in group SUGROUP to su to root, 182 but only if that group has any members. 183 If SUGROUP has no members, allow anyone to su root */ 184 if (pwd->pw_uid == 0 && 185 (gr = getgrnam(SUGROUP)) && *gr->gr_mem) { 186 char **g; 187 188 for (g = gr->gr_mem; ; g++) { 189 if (*g == NULL) 190 errx(1, 191 "you are not listed in the correct secondary group (%s) to su %s.", 192 SUGROUP, user); 193 if (strcmp(username, *g) == 0) 194 break; 195 } 196 } 197 /* if target requires a password, verify it */ 198 if (*pwd->pw_passwd) { 199 p = getpass("Password:"); 200 #ifdef SKEY 201 if (strcasecmp(p, "s/key") == 0) { 202 if (skey_haskey(user)) 203 errx(1, "Sorry, you have no s/key."); 204 else { 205 if (skey_authenticate(user)) { 206 goto badlogin; 207 } 208 } 209 210 } else 211 #endif 212 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 213 badlogin: 214 fprintf(stderr, "Sorry\n"); 215 syslog(LOG_AUTH|LOG_WARNING, 216 "BAD SU %s to %s%s", username, 217 user, ontty()); 218 exit(1); 219 } 220 } 221 } 222 } 223 224 if (asme) { 225 /* if asme and non-standard target shell, must be root */ 226 if (!chshell(pwd->pw_shell) && ruid) 227 errx(1,"permission denied (shell)."); 228 } else if (pwd->pw_shell && *pwd->pw_shell) { 229 shell = pwd->pw_shell; 230 iscsh = UNSET; 231 } else { 232 shell = _PATH_BSHELL; 233 iscsh = NO; 234 } 235 236 if ((p = strrchr(shell, '/')) != NULL) 237 avshell = p+1; 238 else 239 avshell = shell; 240 241 /* if we're forking a csh, we want to slightly muck the args */ 242 if (iscsh == UNSET) 243 iscsh = strstr(avshell, "csh") ? YES : NO; 244 245 /* set permissions */ 246 if (setgid(pwd->pw_gid) < 0) 247 err(1, "setgid"); 248 if (initgroups(user, pwd->pw_gid)) 249 errx(1, "initgroups failed"); 250 if (setuid(pwd->pw_uid) < 0) 251 err(1, "setuid"); 252 253 if (!asme) { 254 if (asthem) { 255 p = getenv("TERM"); 256 cleanenv[0] = NULL; 257 environ = cleanenv; 258 (void)setenv("PATH", _PATH_DEFPATH, 1); 259 if (p) 260 (void)setenv("TERM", p, 1); 261 if (chdir(pwd->pw_dir) < 0) 262 errx(1, "no directory"); 263 } 264 if (asthem || pwd->pw_uid) 265 (void)setenv("USER", pwd->pw_name, 1); 266 (void)setenv("HOME", pwd->pw_dir, 1); 267 (void)setenv("SHELL", shell, 1); 268 } 269 270 if (iscsh == YES) { 271 if (fastlogin) 272 *np-- = "-f"; 273 if (asme) 274 *np-- = "-m"; 275 } 276 277 if (asthem) { 278 avshellbuf[0] = '-'; 279 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 280 avshell = avshellbuf; 281 } else if (iscsh == YES) { 282 /* csh strips the first character... */ 283 avshellbuf[0] = '_'; 284 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 285 avshell = avshellbuf; 286 } 287 *np = avshell; 288 289 if (pwd->pw_change || pwd->pw_expire) 290 (void)gettimeofday(&tp, (struct timezone *)NULL); 291 if (pwd->pw_change) 292 if (tp.tv_sec >= pwd->pw_change) { 293 (void)printf("%s -- %s's password has expired.\n", 294 (ruid ? "Sorry" : "Note"), user); 295 if (ruid != 0) 296 exit(1); 297 } else if (pwd->pw_change - tp.tv_sec < 298 _PASSWORD_WARNDAYS * SECSPERDAY) 299 (void)printf("Warning: %s's password expires on %s", 300 user, ctime(&pwd->pw_change)); 301 if (pwd->pw_expire) 302 if (tp.tv_sec >= pwd->pw_expire) { 303 (void)printf("%s -- %s's account has expired.\n", 304 (ruid ? "Sorry" : "Note"), user); 305 if (ruid != 0) 306 exit(1); 307 } else if (pwd->pw_expire - tp.tv_sec < 308 _PASSWORD_WARNDAYS * SECSPERDAY) 309 (void)printf("Warning: %s's account expires on %s", 310 user, ctime(&pwd->pw_expire)); 311 312 if (ruid != 0) 313 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 314 username, user, ontty()); 315 316 (void)setpriority(PRIO_PROCESS, 0, prio); 317 318 execv(shell, np); 319 err(1, "%s", shell); 320 } 321 322 static int 323 chshell(sh) 324 char *sh; 325 { 326 char *cp; 327 328 while ((cp = getusershell()) != NULL) 329 if (!strcmp(cp, sh)) 330 return (1); 331 return (0); 332 } 333 334 static char * 335 ontty() 336 { 337 char *p; 338 static char buf[MAXPATHLEN + 4]; 339 340 buf[0] = 0; 341 if ((p = ttyname(STDERR_FILENO)) != NULL) 342 (void)snprintf(buf, sizeof buf, " on %s", p); 343 return (buf); 344 } 345 346 #ifdef KERBEROS 347 static int 348 kerberos(username, user, uid) 349 char *username, *user; 350 int uid; 351 { 352 KTEXT_ST ticket; 353 AUTH_DAT authdata; 354 struct hostent *hp; 355 int kerno; 356 u_long faddr; 357 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 358 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 359 360 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 361 return (1); 362 if (koktologin(username, lrealm, user) && !uid) { 363 warnx("kerberos: not in %s's ACL.", user); 364 return (1); 365 } 366 (void)(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT, 367 user, getuid()); 368 369 (void)setenv("KRBTKFILE", krbtkfile, 1); 370 (void)krb_set_tkt_string(krbtkfile); 371 /* 372 * Set real as well as effective ID to 0 for the moment, 373 * to make the kerberos library do the right thing. 374 */ 375 if (setuid(0) < 0) { 376 warn("setuid"); 377 return (1); 378 } 379 380 /* 381 * Little trick here -- if we are su'ing to root, 382 * we need to get a ticket for "xxx.root", where xxx represents 383 * the name of the person su'ing. Otherwise (non-root case), 384 * we need to get a ticket for "yyy.", where yyy represents 385 * the name of the person being su'd to, and the instance is null 386 * 387 * We should have a way to set the ticket lifetime, 388 * with a system default for root. 389 */ 390 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 391 (uid == 0 ? "root" : ""), lrealm, 392 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 393 394 if (kerno != KSUCCESS) { 395 if (kerno == KDC_PR_UNKNOWN) { 396 warnx("kerberos: principal unknown: %s.%s@%s", 397 (uid == 0 ? username : user), 398 (uid == 0 ? "root" : ""), lrealm); 399 return (1); 400 } 401 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 402 syslog(LOG_NOTICE|LOG_AUTH, 403 "BAD Kerberos SU: %s to %s%s: %s", 404 username, user, ontty(), krb_err_txt[kerno]); 405 return (1); 406 } 407 408 if (chown(krbtkfile, uid, -1) < 0) { 409 warn("chown"); 410 (void)unlink(krbtkfile); 411 return (1); 412 } 413 414 (void)setpriority(PRIO_PROCESS, 0, -2); 415 416 if (gethostname(hostname, sizeof(hostname)) == -1) { 417 warn("gethostname"); 418 dest_tkt(); 419 return (1); 420 } 421 422 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 423 savehost[sizeof(savehost) - 1] = '\0'; 424 425 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 426 427 if (kerno == KDC_PR_UNKNOWN) { 428 warnx("Warning: TGT not verified."); 429 syslog(LOG_NOTICE|LOG_AUTH, 430 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 431 username, user, ontty(), krb_err_txt[kerno], 432 "rcmd", savehost); 433 } else if (kerno != KSUCCESS) { 434 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 435 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 436 username, user, ontty(), krb_err_txt[kerno]); 437 dest_tkt(); 438 return (1); 439 } else { 440 if (!(hp = gethostbyname(hostname))) { 441 warnx("can't get addr of %s", hostname); 442 dest_tkt(); 443 return (1); 444 } 445 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 446 447 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 448 &authdata, "")) != KSUCCESS) { 449 warnx("kerberos: unable to verify rcmd ticket: %s\n", 450 krb_err_txt[kerno]); 451 syslog(LOG_NOTICE|LOG_AUTH, 452 "failed su: %s to %s%s: %s", username, 453 user, ontty(), krb_err_txt[kerno]); 454 dest_tkt(); 455 return (1); 456 } 457 } 458 return (0); 459 } 460 461 static int 462 koktologin(name, realm, toname) 463 char *name, *realm, *toname; 464 { 465 AUTH_DAT *kdata; 466 AUTH_DAT kdata_st; 467 468 kdata = &kdata_st; 469 memset((char *)kdata, 0, sizeof(*kdata)); 470 (void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1); 471 (void)strncpy(kdata->pinst, 472 ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1); 473 (void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1); 474 return (kuserok(kdata, toname)); 475 } 476 #endif 477
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