su.c revision 1.14
1 /* $NetBSD: su.c,v 1.14 1997/01/31 22:22:47 ghudson 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 1.14 1997/01/31 22:22:47 ghudson 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, if group 171 * zero has any members. */ 172 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) && 173 *gr->gr_mem) { 174 for (g = gr->gr_mem;; ++g) { 175 if (!*g) 176 errx(1, 177 "you are not in the correct group to su %s.", 178 user); 179 if (!strcmp(username, *g)) 180 break; 181 } 182 } 183 /* if target requires a password, verify it */ 184 if (*pwd->pw_passwd) { 185 p = getpass("Password:"); 186 #ifdef SKEY 187 if (strcasecmp(p, "s/key") == 0) { 188 if (skey_haskey(user)) 189 errx(1, "Sorry, you have no s/key."); 190 else { 191 if (skey_authenticate(user)) { 192 goto badlogin; 193 } 194 } 195 196 } else 197 #endif 198 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 199 badlogin: 200 fprintf(stderr, "Sorry\n"); 201 syslog(LOG_AUTH|LOG_WARNING, 202 "BAD SU %s to %s%s", username, 203 user, ontty()); 204 exit(1); 205 } 206 } 207 } 208 } 209 210 if (asme) { 211 /* if asme and non-standard target shell, must be root */ 212 if (!chshell(pwd->pw_shell) && ruid) 213 errx(1,"permission denied (shell)."); 214 } else if (pwd->pw_shell && *pwd->pw_shell) { 215 shell = pwd->pw_shell; 216 iscsh = UNSET; 217 } else { 218 shell = _PATH_BSHELL; 219 iscsh = NO; 220 } 221 222 if (p = strrchr(shell, '/')) 223 avshell = p+1; 224 else 225 avshell = shell; 226 227 /* if we're forking a csh, we want to slightly muck the args */ 228 if (iscsh == UNSET) 229 iscsh = strstr(avshell, "csh") ? YES : NO; 230 231 /* set permissions */ 232 if (setgid(pwd->pw_gid) < 0) 233 err(1, "setgid"); 234 if (initgroups(user, pwd->pw_gid)) 235 errx(1, "initgroups failed"); 236 if (setuid(pwd->pw_uid) < 0) 237 err(1, "setuid"); 238 239 if (!asme) { 240 if (asthem) { 241 p = getenv("TERM"); 242 cleanenv[0] = NULL; 243 environ = cleanenv; 244 (void)setenv("PATH", _PATH_DEFPATH, 1); 245 if (p) 246 (void)setenv("TERM", p, 1); 247 if (chdir(pwd->pw_dir) < 0) 248 errx(1, "no directory"); 249 } 250 if (asthem || pwd->pw_uid) 251 (void)setenv("USER", pwd->pw_name, 1); 252 (void)setenv("HOME", pwd->pw_dir, 1); 253 (void)setenv("SHELL", shell, 1); 254 } 255 256 if (iscsh == YES) { 257 if (fastlogin) 258 *np-- = "-f"; 259 if (asme) 260 *np-- = "-m"; 261 } 262 263 if (asthem) { 264 avshellbuf[0] = '-'; 265 strcpy(avshellbuf+1, avshell); 266 avshell = avshellbuf; 267 } else if (iscsh == YES) { 268 /* csh strips the first character... */ 269 avshellbuf[0] = '_'; 270 strcpy(avshellbuf+1, avshell); 271 avshell = avshellbuf; 272 } 273 *np = avshell; 274 275 if (ruid != 0) 276 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 277 username, user, ontty()); 278 279 (void)setpriority(PRIO_PROCESS, 0, prio); 280 281 execv(shell, np); 282 err(1, "%s", shell); 283 } 284 285 static int 286 chshell(sh) 287 char *sh; 288 { 289 char *cp; 290 char *getusershell(); 291 292 while ((cp = getusershell()) != NULL) 293 if (!strcmp(cp, sh)) 294 return (1); 295 return (0); 296 } 297 298 static char * 299 ontty() 300 { 301 char *p, *ttyname(); 302 static char buf[MAXPATHLEN + 4]; 303 304 buf[0] = 0; 305 if (p = ttyname(STDERR_FILENO)) 306 sprintf(buf, " on %s", p); 307 return (buf); 308 } 309 310 #ifdef KERBEROS 311 static int 312 kerberos(username, user, uid) 313 char *username, *user; 314 int uid; 315 { 316 KTEXT_ST ticket; 317 AUTH_DAT authdata; 318 struct hostent *hp; 319 register char *p; 320 int kerno; 321 u_long faddr; 322 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 323 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 324 char *ontty(), *krb_get_phost(); 325 326 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 327 return (1); 328 if (koktologin(username, lrealm, user) && !uid) { 329 warnx("kerberos: not in %s's ACL.", user); 330 return (1); 331 } 332 (void)sprintf(krbtkfile, "%s_%s_%d", TKT_ROOT, user, getuid()); 333 334 (void)setenv("KRBTKFILE", krbtkfile, 1); 335 (void)krb_set_tkt_string(krbtkfile); 336 /* 337 * Set real as well as effective ID to 0 for the moment, 338 * to make the kerberos library do the right thing. 339 */ 340 if (setuid(0) < 0) { 341 warn("setuid"); 342 return (1); 343 } 344 345 /* 346 * Little trick here -- if we are su'ing to root, 347 * we need to get a ticket for "xxx.root", where xxx represents 348 * the name of the person su'ing. Otherwise (non-root case), 349 * we need to get a ticket for "yyy.", where yyy represents 350 * the name of the person being su'd to, and the instance is null 351 * 352 * We should have a way to set the ticket lifetime, 353 * with a system default for root. 354 */ 355 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 356 (uid == 0 ? "root" : ""), lrealm, 357 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 358 359 if (kerno != KSUCCESS) { 360 if (kerno == KDC_PR_UNKNOWN) { 361 warnx("kerberos: principal unknown: %s.%s@%s", 362 (uid == 0 ? username : user), 363 (uid == 0 ? "root" : ""), lrealm); 364 return (1); 365 } 366 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 367 syslog(LOG_NOTICE|LOG_AUTH, 368 "BAD Kerberos SU: %s to %s%s: %s", 369 username, user, ontty(), krb_err_txt[kerno]); 370 return (1); 371 } 372 373 if (chown(krbtkfile, uid, -1) < 0) { 374 warn("chown"); 375 (void)unlink(krbtkfile); 376 return (1); 377 } 378 379 (void)setpriority(PRIO_PROCESS, 0, -2); 380 381 if (gethostname(hostname, sizeof(hostname)) == -1) { 382 warn("gethostname"); 383 dest_tkt(); 384 return (1); 385 } 386 387 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 388 savehost[sizeof(savehost) - 1] = '\0'; 389 390 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 391 392 if (kerno == KDC_PR_UNKNOWN) { 393 warnx("Warning: TGT not verified."); 394 syslog(LOG_NOTICE|LOG_AUTH, 395 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 396 username, user, ontty(), krb_err_txt[kerno], 397 "rcmd", savehost); 398 } else if (kerno != KSUCCESS) { 399 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 400 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 401 username, user, ontty(), krb_err_txt[kerno]); 402 dest_tkt(); 403 return (1); 404 } else { 405 if (!(hp = gethostbyname(hostname))) { 406 warnx("can't get addr of %s", hostname); 407 dest_tkt(); 408 return (1); 409 } 410 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 411 412 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 413 &authdata, "")) != KSUCCESS) { 414 warnx("kerberos: unable to verify rcmd ticket: %s\n", 415 krb_err_txt[kerno]); 416 syslog(LOG_NOTICE|LOG_AUTH, 417 "failed su: %s to %s%s: %s", username, 418 user, ontty(), krb_err_txt[kerno]); 419 dest_tkt(); 420 return (1); 421 } 422 } 423 return (0); 424 } 425 426 static int 427 koktologin(name, realm, toname) 428 char *name, *realm, *toname; 429 { 430 register AUTH_DAT *kdata; 431 AUTH_DAT kdata_st; 432 433 kdata = &kdata_st; 434 memset((char *)kdata, 0, sizeof(*kdata)); 435 (void)strcpy(kdata->pname, name); 436 (void)strcpy(kdata->pinst, 437 ((strcmp(toname, "root") == 0) ? "root" : "")); 438 (void)strcpy(kdata->prealm, realm); 439 return (kuserok(kdata, toname)); 440 } 441 #endif 442
Indexes created Mon Sep 29 21:09:56 GMT 2025