su.c revision 1.23
1 /* $NetBSD: su.c,v 1.23 1998/07/06 11:36:14 mrg 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 1.23 1998/07/06 11:36:14 mrg 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 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 username = strdup(pwd->pw_name); 158 if (username == NULL) 159 err(1, "strdup"); 160 161 /* get target login information, default to root */ 162 user = *argv ? *argv : "root"; 163 np = *argv ? argv : argv-1; 164 165 if ((pwd = getpwnam(user)) == NULL) 166 errx(1, "unknown login %s", user); 167 168 if (ruid) { 169 #ifdef KERBEROS 170 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 171 #endif 172 { 173 /* Only allow those in group SUGROUP to su to root, 174 but only if that group has any members. 175 If SUGROUP has no members, allow anyone to su root */ 176 if (pwd->pw_uid == 0 && 177 (gr = getgrnam(SUGROUP)) && *gr->gr_mem) { 178 char **g; 179 180 for (g = gr->gr_mem; ; g++) { 181 if (*g == NULL) 182 errx(1, 183 "you are not listed in the correct secondary group (%s) to su %s.", 184 SUGROUP, user); 185 if (strcmp(username, *g) == 0) 186 break; 187 } 188 } 189 /* if target requires a password, verify it */ 190 if (*pwd->pw_passwd) { 191 p = getpass("Password:"); 192 #ifdef SKEY 193 if (strcasecmp(p, "s/key") == 0) { 194 if (skey_haskey(user)) 195 errx(1, "Sorry, you have no s/key."); 196 else { 197 if (skey_authenticate(user)) { 198 goto badlogin; 199 } 200 } 201 202 } else 203 #endif 204 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 205 badlogin: 206 fprintf(stderr, "Sorry\n"); 207 syslog(LOG_AUTH|LOG_WARNING, 208 "BAD SU %s to %s%s", username, 209 user, ontty()); 210 exit(1); 211 } 212 } 213 } 214 } 215 216 if (asme) { 217 /* if asme and non-standard target shell, must be root */ 218 if (!chshell(pwd->pw_shell) && ruid) 219 errx(1,"permission denied (shell)."); 220 } else if (pwd->pw_shell && *pwd->pw_shell) { 221 shell = pwd->pw_shell; 222 iscsh = UNSET; 223 } else { 224 shell = _PATH_BSHELL; 225 iscsh = NO; 226 } 227 228 if ((p = strrchr(shell, '/')) != NULL) 229 avshell = p+1; 230 else 231 avshell = shell; 232 233 /* if we're forking a csh, we want to slightly muck the args */ 234 if (iscsh == UNSET) 235 iscsh = strstr(avshell, "csh") ? YES : NO; 236 237 /* set permissions */ 238 if (setgid(pwd->pw_gid) < 0) 239 err(1, "setgid"); 240 if (initgroups(user, pwd->pw_gid)) 241 errx(1, "initgroups failed"); 242 if (setuid(pwd->pw_uid) < 0) 243 err(1, "setuid"); 244 245 if (!asme) { 246 if (asthem) { 247 p = getenv("TERM"); 248 cleanenv[0] = NULL; 249 environ = cleanenv; 250 (void)setenv("PATH", _PATH_DEFPATH, 1); 251 if (p) 252 (void)setenv("TERM", p, 1); 253 if (chdir(pwd->pw_dir) < 0) 254 errx(1, "no directory"); 255 } 256 if (asthem || pwd->pw_uid) 257 (void)setenv("USER", pwd->pw_name, 1); 258 (void)setenv("HOME", pwd->pw_dir, 1); 259 (void)setenv("SHELL", shell, 1); 260 } 261 262 if (iscsh == YES) { 263 if (fastlogin) 264 *np-- = "-f"; 265 if (asme) 266 *np-- = "-m"; 267 } 268 269 if (asthem) { 270 avshellbuf[0] = '-'; 271 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 272 avshell = avshellbuf; 273 } else if (iscsh == YES) { 274 /* csh strips the first character... */ 275 avshellbuf[0] = '_'; 276 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 277 avshell = avshellbuf; 278 } 279 *np = avshell; 280 281 if (pwd->pw_change || pwd->pw_expire) 282 (void)gettimeofday(&tp, (struct timezone *)NULL); 283 if (pwd->pw_change) 284 if (tp.tv_sec >= pwd->pw_change) { 285 (void)printf("%s -- %s's password has expired.\n", 286 (ruid ? "Sorry" : "Note"), user); 287 if (ruid != 0) 288 exit(1); 289 } else if (pwd->pw_change - tp.tv_sec < 290 _PASSWORD_WARNDAYS * SECSPERDAY) 291 (void)printf("Warning: %s's password expires on %s", 292 user, ctime(&pwd->pw_change)); 293 if (pwd->pw_expire) 294 if (tp.tv_sec >= pwd->pw_expire) { 295 (void)printf("%s -- %s's account has expired.\n", 296 (ruid ? "Sorry" : "Note"), user); 297 if (ruid != 0) 298 exit(1); 299 } else if (pwd->pw_expire - tp.tv_sec < 300 _PASSWORD_WARNDAYS * SECSPERDAY) 301 (void)printf("Warning: %s's account expires on %s", 302 user, ctime(&pwd->pw_expire)); 303 304 if (ruid != 0) 305 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 306 username, user, ontty()); 307 308 (void)setpriority(PRIO_PROCESS, 0, prio); 309 310 execv(shell, np); 311 err(1, "%s", shell); 312 } 313 314 static int 315 chshell(sh) 316 char *sh; 317 { 318 char *cp; 319 320 while ((cp = getusershell()) != NULL) 321 if (!strcmp(cp, sh)) 322 return (1); 323 return (0); 324 } 325 326 static char * 327 ontty() 328 { 329 char *p; 330 static char buf[MAXPATHLEN + 4]; 331 332 buf[0] = 0; 333 if ((p = ttyname(STDERR_FILENO)) != NULL) 334 (void)snprintf(buf, sizeof buf, " on %s", p); 335 return (buf); 336 } 337 338 #ifdef KERBEROS 339 static int 340 kerberos(username, user, uid) 341 char *username, *user; 342 int uid; 343 { 344 KTEXT_ST ticket; 345 AUTH_DAT authdata; 346 struct hostent *hp; 347 int kerno; 348 u_long faddr; 349 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 350 char hostname[MAXHOSTNAMELEN + 1], savehost[MAXHOSTNAMELEN + 1]; 351 352 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 353 return (1); 354 if (koktologin(username, lrealm, user) && !uid) { 355 warnx("kerberos: not in %s's ACL.", user); 356 return (1); 357 } 358 (void)(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT, 359 user, getuid()); 360 361 (void)setenv("KRBTKFILE", krbtkfile, 1); 362 (void)krb_set_tkt_string(krbtkfile); 363 /* 364 * Set real as well as effective ID to 0 for the moment, 365 * to make the kerberos library do the right thing. 366 */ 367 if (setuid(0) < 0) { 368 warn("setuid"); 369 return (1); 370 } 371 372 /* 373 * Little trick here -- if we are su'ing to root, 374 * we need to get a ticket for "xxx.root", where xxx represents 375 * the name of the person su'ing. Otherwise (non-root case), 376 * we need to get a ticket for "yyy.", where yyy represents 377 * the name of the person being su'd to, and the instance is null 378 * 379 * We should have a way to set the ticket lifetime, 380 * with a system default for root. 381 */ 382 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 383 (uid == 0 ? "root" : ""), lrealm, 384 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 385 386 if (kerno != KSUCCESS) { 387 if (kerno == KDC_PR_UNKNOWN) { 388 warnx("kerberos: principal unknown: %s.%s@%s", 389 (uid == 0 ? username : user), 390 (uid == 0 ? "root" : ""), lrealm); 391 return (1); 392 } 393 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 394 syslog(LOG_NOTICE|LOG_AUTH, 395 "BAD Kerberos SU: %s to %s%s: %s", 396 username, user, ontty(), krb_err_txt[kerno]); 397 return (1); 398 } 399 400 if (chown(krbtkfile, uid, -1) < 0) { 401 warn("chown"); 402 (void)unlink(krbtkfile); 403 return (1); 404 } 405 406 (void)setpriority(PRIO_PROCESS, 0, -2); 407 408 if (gethostname(hostname, sizeof(hostname)) == -1) { 409 warn("gethostname"); 410 dest_tkt(); 411 return (1); 412 } 413 hostname[sizeof(hostname) - 1] = '\0'; 414 415 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 416 savehost[sizeof(savehost) - 1] = '\0'; 417 418 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 419 420 if (kerno == KDC_PR_UNKNOWN) { 421 warnx("Warning: TGT not verified."); 422 syslog(LOG_NOTICE|LOG_AUTH, 423 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 424 username, user, ontty(), krb_err_txt[kerno], 425 "rcmd", savehost); 426 } else if (kerno != KSUCCESS) { 427 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 428 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 429 username, user, ontty(), krb_err_txt[kerno]); 430 dest_tkt(); 431 return (1); 432 } else { 433 if (!(hp = gethostbyname(hostname))) { 434 warnx("can't get addr of %s", hostname); 435 dest_tkt(); 436 return (1); 437 } 438 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 439 440 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 441 &authdata, "")) != KSUCCESS) { 442 warnx("kerberos: unable to verify rcmd ticket: %s\n", 443 krb_err_txt[kerno]); 444 syslog(LOG_NOTICE|LOG_AUTH, 445 "failed su: %s to %s%s: %s", username, 446 user, ontty(), krb_err_txt[kerno]); 447 dest_tkt(); 448 return (1); 449 } 450 } 451 return (0); 452 } 453 454 static int 455 koktologin(name, realm, toname) 456 char *name, *realm, *toname; 457 { 458 AUTH_DAT *kdata; 459 AUTH_DAT kdata_st; 460 461 kdata = &kdata_st; 462 memset((char *)kdata, 0, sizeof(*kdata)); 463 (void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1); 464 (void)strncpy(kdata->pinst, 465 ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1); 466 (void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1); 467 return (kuserok(kdata, toname)); 468 } 469 #endif 470
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