su.c revision 1.27
1 /* $NetBSD: su.c,v 1.27 1998/10/14 00:56:48 wsanchez 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 1.27 1998/10/14 00:56:48 wsanchez 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 #ifdef SKEY 61 #include <skey.h> 62 #endif 63 #include <stdlib.h> 64 #include <string.h> 65 #include <syslog.h> 66 #include <time.h> 67 #include <tzfile.h> 68 #include <unistd.h> 69 70 #ifdef KERBEROS 71 #include <kerberosIV/des.h> 72 #include <kerberosIV/krb.h> 73 #include <netdb.h> 74 75 #define ARGSTR "-Kflm" 76 77 int use_kerberos = 1; 78 79 static int kerberos __P((char *, char *, int)); 80 static int koktologin __P((char *, char *, char *)); 81 82 #else 83 #define ARGSTR "-flm" 84 #endif 85 86 #ifndef SUGROUP 87 #define SUGROUP "wheel" 88 #endif 89 90 91 int main __P((int, char **)); 92 93 static int chshell __P((const char *)); 94 static char *ontty __P((void)); 95 96 97 int 98 main(argc, argv) 99 int argc; 100 char **argv; 101 { 102 extern char *__progname; 103 extern char **environ; 104 struct passwd *pwd; 105 char *p; 106 struct group *gr; 107 struct timeval tp; 108 uid_t ruid; 109 int asme, ch, asthem, fastlogin, prio; 110 enum { UNSET, YES, NO } iscsh = UNSET; 111 char *user, *shell, *avshell, *username, *cleanenv[10], **np; 112 char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN]; 113 114 asme = asthem = fastlogin = 0; 115 shell = NULL; 116 while ((ch = getopt(argc, argv, ARGSTR)) != -1) 117 switch((char)ch) { 118 #ifdef KERBEROS 119 case 'K': 120 use_kerberos = 0; 121 break; 122 #endif 123 case 'f': 124 fastlogin = 1; 125 break; 126 case '-': 127 case 'l': 128 asme = 0; 129 asthem = 1; 130 break; 131 case 'm': 132 asme = 1; 133 asthem = 0; 134 break; 135 case '?': 136 default: 137 (void)fprintf(stderr, 138 "Usage: %s [%s] [login [shell arguments]]\n", 139 __progname, ARGSTR); 140 exit(1); 141 } 142 argv += optind; 143 144 errno = 0; 145 prio = getpriority(PRIO_PROCESS, 0); 146 if (errno) 147 prio = 0; 148 (void)setpriority(PRIO_PROCESS, 0, -2); 149 openlog("su", LOG_CONS, 0); 150 151 /* get current login name and shell */ 152 ruid = getuid(); 153 username = getlogin(); 154 if (username == NULL || (pwd = getpwnam(username)) == NULL || 155 pwd->pw_uid != ruid) 156 pwd = getpwuid(ruid); 157 if (pwd == NULL) 158 errx(1, "who are you?"); 159 username = strdup(pwd->pw_name); 160 if (username == NULL) 161 err(1, "strdup"); 162 163 if (asme) { 164 if (pwd->pw_shell && *pwd->pw_shell) { 165 shell = strncpy(shellbuf, pwd->pw_shell, 166 sizeof(shellbuf) - 1); 167 shellbuf[sizeof(shellbuf) - 1] = '\0'; 168 } else { 169 shell = _PATH_BSHELL; 170 iscsh = NO; 171 } 172 } 173 /* get target login information, default to root */ 174 user = *argv ? *argv : "root"; 175 np = *argv ? argv : argv-1; 176 177 if ((pwd = getpwnam(user)) == NULL) 178 errx(1, "unknown login %s", user); 179 180 if (ruid 181 #ifdef KERBEROS 182 && (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 183 #endif 184 ) { 185 /* 186 * Only allow those in group SUGROUP to su to root, 187 * but only if that group has any members. 188 * If SUGROUP has no members, allow anyone to su root 189 */ 190 if (pwd->pw_uid == 0 && 191 (gr = getgrnam(SUGROUP)) && *gr->gr_mem) { 192 char **g; 193 194 for (g = gr->gr_mem; ; g++) { 195 if (*g == NULL) 196 errx(1, 197 "you are not listed in the correct secondary group (%s) to su %s.", 198 SUGROUP, user); 199 if (strcmp(username, *g) == 0) 200 break; 201 } 202 } 203 /* if target requires a password, verify it */ 204 if (*pwd->pw_passwd) { 205 p = getpass("Password:"); 206 #ifdef SKEY 207 if (strcasecmp(p, "s/key") == 0) { 208 if (skey_haskey(user)) 209 errx(1, "Sorry, you have no s/key."); 210 else { 211 if (skey_authenticate(user)) { 212 goto badlogin; 213 } 214 } 215 216 } else 217 #endif 218 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 219 #ifdef SKEY 220 badlogin: 221 #endif 222 fprintf(stderr, "Sorry\n"); 223 syslog(LOG_AUTH|LOG_WARNING, 224 "BAD SU %s to %s%s", username, 225 user, ontty()); 226 exit(1); 227 } 228 } 229 } 230 231 if (asme) { 232 /* if asme and non-standard target shell, must be root */ 233 if (!chshell(pwd->pw_shell) && ruid) 234 errx(1,"permission denied (shell)."); 235 } else if (pwd->pw_shell && *pwd->pw_shell) { 236 shell = pwd->pw_shell; 237 iscsh = UNSET; 238 } else { 239 shell = _PATH_BSHELL; 240 iscsh = NO; 241 } 242 243 if ((p = strrchr(shell, '/')) != NULL) 244 avshell = p+1; 245 else 246 avshell = shell; 247 248 /* if we're forking a csh, we want to slightly muck the args */ 249 if (iscsh == UNSET) 250 iscsh = strstr(avshell, "csh") ? YES : NO; 251 252 /* set permissions */ 253 if (setgid(pwd->pw_gid) < 0) 254 err(1, "setgid"); 255 if (initgroups(user, pwd->pw_gid)) 256 errx(1, "initgroups failed"); 257 if (setuid(pwd->pw_uid) < 0) 258 err(1, "setuid"); 259 260 if (!asme) { 261 if (asthem) { 262 p = getenv("TERM"); 263 cleanenv[0] = NULL; 264 environ = cleanenv; 265 (void)setenv("PATH", _PATH_DEFPATH, 1); 266 if (p) 267 (void)setenv("TERM", p, 1); 268 if (chdir(pwd->pw_dir) < 0) 269 errx(1, "no directory"); 270 } 271 if (asthem || pwd->pw_uid) 272 (void)setenv("USER", pwd->pw_name, 1); 273 (void)setenv("HOME", pwd->pw_dir, 1); 274 (void)setenv("SHELL", shell, 1); 275 } 276 277 if (iscsh == YES) { 278 if (fastlogin) 279 *np-- = "-f"; 280 if (asme) 281 *np-- = "-m"; 282 } 283 284 if (asthem) { 285 avshellbuf[0] = '-'; 286 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 287 avshell = avshellbuf; 288 } else if (iscsh == YES) { 289 /* csh strips the first character... */ 290 avshellbuf[0] = '_'; 291 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 292 avshell = avshellbuf; 293 } 294 *np = avshell; 295 296 if (pwd->pw_change || pwd->pw_expire) 297 (void)gettimeofday(&tp, (struct timezone *)NULL); 298 if (pwd->pw_change) { 299 if (tp.tv_sec >= pwd->pw_change) { 300 (void)printf("%s -- %s's password has expired.\n", 301 (ruid ? "Sorry" : "Note"), user); 302 if (ruid != 0) 303 exit(1); 304 } else if (pwd->pw_change - tp.tv_sec < 305 _PASSWORD_WARNDAYS * SECSPERDAY) 306 (void)printf("Warning: %s's password expires on %s", 307 user, ctime(&pwd->pw_change)); 308 } 309 if (pwd->pw_expire) { 310 if (tp.tv_sec >= pwd->pw_expire) { 311 (void)printf("%s -- %s's account has expired.\n", 312 (ruid ? "Sorry" : "Note"), user); 313 if (ruid != 0) 314 exit(1); 315 } else if (pwd->pw_expire - tp.tv_sec < 316 _PASSWORD_WARNDAYS * SECSPERDAY) 317 (void)printf("Warning: %s's account expires on %s", 318 user, ctime(&pwd->pw_expire)); 319 } 320 if (ruid != 0) 321 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 322 username, user, ontty()); 323 324 (void)setpriority(PRIO_PROCESS, 0, prio); 325 326 execv(shell, np); 327 err(1, "%s", shell); 328 /* NOTREACHED */ 329 } 330 331 static int 332 chshell(sh) 333 const char *sh; 334 { 335 const char *cp; 336 337 while ((cp = getusershell()) != NULL) 338 if (!strcmp(cp, sh)) 339 return (1); 340 return (0); 341 } 342 343 static char * 344 ontty() 345 { 346 char *p; 347 static char buf[MAXPATHLEN + 4]; 348 349 buf[0] = 0; 350 if ((p = ttyname(STDERR_FILENO)) != NULL) 351 (void)snprintf(buf, sizeof buf, " on %s", p); 352 return (buf); 353 } 354 355 #ifdef KERBEROS 356 static int 357 kerberos(username, user, uid) 358 char *username, *user; 359 int uid; 360 { 361 KTEXT_ST ticket; 362 AUTH_DAT authdata; 363 struct hostent *hp; 364 int kerno; 365 u_long faddr; 366 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 367 char hostname[MAXHOSTNAMELEN + 1], savehost[MAXHOSTNAMELEN + 1]; 368 369 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 370 return (1); 371 if (koktologin(username, lrealm, user) && !uid) { 372 warnx("kerberos: not in %s's ACL.", user); 373 return (1); 374 } 375 (void)(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT, 376 user, getuid()); 377 378 (void)setenv("KRBTKFILE", krbtkfile, 1); 379 (void)krb_set_tkt_string(krbtkfile); 380 /* 381 * Set real as well as effective ID to 0 for the moment, 382 * to make the kerberos library do the right thing. 383 */ 384 if (setuid(0) < 0) { 385 warn("setuid"); 386 return (1); 387 } 388 389 /* 390 * Little trick here -- if we are su'ing to root, 391 * we need to get a ticket for "xxx.root", where xxx represents 392 * the name of the person su'ing. Otherwise (non-root case), 393 * we need to get a ticket for "yyy.", where yyy represents 394 * the name of the person being su'd to, and the instance is null 395 * 396 * We should have a way to set the ticket lifetime, 397 * with a system default for root. 398 */ 399 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 400 (uid == 0 ? "root" : ""), lrealm, 401 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 402 403 if (kerno != KSUCCESS) { 404 if (kerno == KDC_PR_UNKNOWN) { 405 warnx("kerberos: principal unknown: %s.%s@%s", 406 (uid == 0 ? username : user), 407 (uid == 0 ? "root" : ""), lrealm); 408 return (1); 409 } 410 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 411 syslog(LOG_NOTICE|LOG_AUTH, 412 "BAD Kerberos SU: %s to %s%s: %s", 413 username, user, ontty(), krb_err_txt[kerno]); 414 return (1); 415 } 416 417 if (chown(krbtkfile, uid, -1) < 0) { 418 warn("chown"); 419 (void)unlink(krbtkfile); 420 return (1); 421 } 422 423 (void)setpriority(PRIO_PROCESS, 0, -2); 424 425 if (gethostname(hostname, sizeof(hostname)) == -1) { 426 warn("gethostname"); 427 dest_tkt(); 428 return (1); 429 } 430 hostname[sizeof(hostname) - 1] = '\0'; 431 432 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 433 savehost[sizeof(savehost) - 1] = '\0'; 434 435 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 436 437 if (kerno == KDC_PR_UNKNOWN) { 438 warnx("Warning: TGT not verified."); 439 syslog(LOG_NOTICE|LOG_AUTH, 440 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 441 username, user, ontty(), krb_err_txt[kerno], 442 "rcmd", savehost); 443 } else if (kerno != KSUCCESS) { 444 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 445 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 446 username, user, ontty(), krb_err_txt[kerno]); 447 dest_tkt(); 448 return (1); 449 } else { 450 if (!(hp = gethostbyname(hostname))) { 451 warnx("can't get addr of %s", hostname); 452 dest_tkt(); 453 return (1); 454 } 455 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 456 457 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 458 &authdata, "")) != KSUCCESS) { 459 warnx("kerberos: unable to verify rcmd ticket: %s\n", 460 krb_err_txt[kerno]); 461 syslog(LOG_NOTICE|LOG_AUTH, 462 "failed su: %s to %s%s: %s", username, 463 user, ontty(), krb_err_txt[kerno]); 464 dest_tkt(); 465 return (1); 466 } 467 } 468 return (0); 469 } 470 471 static int 472 koktologin(name, realm, toname) 473 char *name, *realm, *toname; 474 { 475 AUTH_DAT *kdata; 476 AUTH_DAT kdata_st; 477 478 kdata = &kdata_st; 479 memset((char *)kdata, 0, sizeof(*kdata)); 480 (void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1); 481 (void)strncpy(kdata->pinst, 482 ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1); 483 (void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1); 484 return (kuserok(kdata, toname)); 485 } 486 #endif 487
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