su.c revision 1.16
1 /* $NetBSD: su.c,v 1.16 1997/03/04 00:21:13 explorer 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 1.16 1997/03/04 00:21:13 explorer 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 = strncpy(shellbuf, pwd->pw_shell, 152 sizeof(shellbuf) + 1); 153 else { 154 shell = _PATH_BSHELL; 155 iscsh = NO; 156 } 157 158 /* get target login information, default to root */ 159 user = *argv ? *argv : "root"; 160 np = *argv ? argv : argv-1; 161 162 if ((pwd = getpwnam(user)) == NULL) { 163 errx(1, "unknown login %s", user); 164 } 165 166 if (ruid) { 167 #ifdef KERBEROS 168 if (!use_kerberos || kerberos(username, user, pwd->pw_uid)) 169 #endif 170 { 171 /* only allow those in group zero to su to root, if group 172 * zero has any members. */ 173 if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)) && 174 *gr->gr_mem) { 175 for (g = gr->gr_mem;; ++g) { 176 if (!*g) 177 errx(1, 178 "you are not in the correct group to su %s.", 179 user); 180 if (!strcmp(username, *g)) 181 break; 182 } 183 } 184 /* if target requires a password, verify it */ 185 if (*pwd->pw_passwd) { 186 p = getpass("Password:"); 187 #ifdef SKEY 188 if (strcasecmp(p, "s/key") == 0) { 189 if (skey_haskey(user)) 190 errx(1, "Sorry, you have no s/key."); 191 else { 192 if (skey_authenticate(user)) { 193 goto badlogin; 194 } 195 } 196 197 } else 198 #endif 199 if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) { 200 badlogin: 201 fprintf(stderr, "Sorry\n"); 202 syslog(LOG_AUTH|LOG_WARNING, 203 "BAD SU %s to %s%s", username, 204 user, ontty()); 205 exit(1); 206 } 207 } 208 } 209 } 210 211 if (asme) { 212 /* if asme and non-standard target shell, must be root */ 213 if (!chshell(pwd->pw_shell) && ruid) 214 errx(1,"permission denied (shell)."); 215 } else if (pwd->pw_shell && *pwd->pw_shell) { 216 shell = pwd->pw_shell; 217 iscsh = UNSET; 218 } else { 219 shell = _PATH_BSHELL; 220 iscsh = NO; 221 } 222 223 if (p = strrchr(shell, '/')) 224 avshell = p+1; 225 else 226 avshell = shell; 227 228 /* if we're forking a csh, we want to slightly muck the args */ 229 if (iscsh == UNSET) 230 iscsh = strstr(avshell, "csh") ? YES : NO; 231 232 /* set permissions */ 233 if (setgid(pwd->pw_gid) < 0) 234 err(1, "setgid"); 235 if (initgroups(user, pwd->pw_gid)) 236 errx(1, "initgroups failed"); 237 if (setuid(pwd->pw_uid) < 0) 238 err(1, "setuid"); 239 240 if (!asme) { 241 if (asthem) { 242 p = getenv("TERM"); 243 cleanenv[0] = NULL; 244 environ = cleanenv; 245 (void)setenv("PATH", _PATH_DEFPATH, 1); 246 if (p) 247 (void)setenv("TERM", p, 1); 248 if (chdir(pwd->pw_dir) < 0) 249 errx(1, "no directory"); 250 } 251 if (asthem || pwd->pw_uid) 252 (void)setenv("USER", pwd->pw_name, 1); 253 (void)setenv("HOME", pwd->pw_dir, 1); 254 (void)setenv("SHELL", shell, 1); 255 } 256 257 if (iscsh == YES) { 258 if (fastlogin) 259 *np-- = "-f"; 260 if (asme) 261 *np-- = "-m"; 262 } 263 264 if (asthem) { 265 avshellbuf[0] = '-'; 266 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 267 avshell = avshellbuf; 268 } else if (iscsh == YES) { 269 /* csh strips the first character... */ 270 avshellbuf[0] = '_'; 271 (void)strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2); 272 avshell = avshellbuf; 273 } 274 *np = avshell; 275 276 if (ruid != 0) 277 syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s", 278 username, user, ontty()); 279 280 (void)setpriority(PRIO_PROCESS, 0, prio); 281 282 execv(shell, np); 283 err(1, "%s", shell); 284 } 285 286 static int 287 chshell(sh) 288 char *sh; 289 { 290 char *cp; 291 char *getusershell(); 292 293 while ((cp = getusershell()) != NULL) 294 if (!strcmp(cp, sh)) 295 return (1); 296 return (0); 297 } 298 299 static char * 300 ontty() 301 { 302 char *p, *ttyname(); 303 static char buf[MAXPATHLEN + 4]; 304 305 buf[0] = 0; 306 if (p = ttyname(STDERR_FILENO)) 307 (void)snprintf(buf, sizeof buf, " on %s", p); 308 return (buf); 309 } 310 311 #ifdef KERBEROS 312 static int 313 kerberos(username, user, uid) 314 char *username, *user; 315 int uid; 316 { 317 KTEXT_ST ticket; 318 AUTH_DAT authdata; 319 struct hostent *hp; 320 register char *p; 321 int kerno; 322 u_long faddr; 323 char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN]; 324 char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN]; 325 char *ontty(), *krb_get_phost(); 326 327 if (krb_get_lrealm(lrealm, 1) != KSUCCESS) 328 return (1); 329 if (koktologin(username, lrealm, user) && !uid) { 330 warnx("kerberos: not in %s's ACL.", user); 331 return (1); 332 } 333 (void)(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT, 334 user, getuid()); 335 336 (void)setenv("KRBTKFILE", krbtkfile, 1); 337 (void)krb_set_tkt_string(krbtkfile); 338 /* 339 * Set real as well as effective ID to 0 for the moment, 340 * to make the kerberos library do the right thing. 341 */ 342 if (setuid(0) < 0) { 343 warn("setuid"); 344 return (1); 345 } 346 347 /* 348 * Little trick here -- if we are su'ing to root, 349 * we need to get a ticket for "xxx.root", where xxx represents 350 * the name of the person su'ing. Otherwise (non-root case), 351 * we need to get a ticket for "yyy.", where yyy represents 352 * the name of the person being su'd to, and the instance is null 353 * 354 * We should have a way to set the ticket lifetime, 355 * with a system default for root. 356 */ 357 kerno = krb_get_pw_in_tkt((uid == 0 ? username : user), 358 (uid == 0 ? "root" : ""), lrealm, 359 "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0); 360 361 if (kerno != KSUCCESS) { 362 if (kerno == KDC_PR_UNKNOWN) { 363 warnx("kerberos: principal unknown: %s.%s@%s", 364 (uid == 0 ? username : user), 365 (uid == 0 ? "root" : ""), lrealm); 366 return (1); 367 } 368 warnx("kerberos: unable to su: %s", krb_err_txt[kerno]); 369 syslog(LOG_NOTICE|LOG_AUTH, 370 "BAD Kerberos SU: %s to %s%s: %s", 371 username, user, ontty(), krb_err_txt[kerno]); 372 return (1); 373 } 374 375 if (chown(krbtkfile, uid, -1) < 0) { 376 warn("chown"); 377 (void)unlink(krbtkfile); 378 return (1); 379 } 380 381 (void)setpriority(PRIO_PROCESS, 0, -2); 382 383 if (gethostname(hostname, sizeof(hostname)) == -1) { 384 warn("gethostname"); 385 dest_tkt(); 386 return (1); 387 } 388 389 (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost)); 390 savehost[sizeof(savehost) - 1] = '\0'; 391 392 kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33); 393 394 if (kerno == KDC_PR_UNKNOWN) { 395 warnx("Warning: TGT not verified."); 396 syslog(LOG_NOTICE|LOG_AUTH, 397 "%s to %s%s, TGT not verified (%s); %s.%s not registered?", 398 username, user, ontty(), krb_err_txt[kerno], 399 "rcmd", savehost); 400 } else if (kerno != KSUCCESS) { 401 warnx("Unable to use TGT: %s", krb_err_txt[kerno]); 402 syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s", 403 username, user, ontty(), krb_err_txt[kerno]); 404 dest_tkt(); 405 return (1); 406 } else { 407 if (!(hp = gethostbyname(hostname))) { 408 warnx("can't get addr of %s", hostname); 409 dest_tkt(); 410 return (1); 411 } 412 memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr)); 413 414 if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr, 415 &authdata, "")) != KSUCCESS) { 416 warnx("kerberos: unable to verify rcmd ticket: %s\n", 417 krb_err_txt[kerno]); 418 syslog(LOG_NOTICE|LOG_AUTH, 419 "failed su: %s to %s%s: %s", username, 420 user, ontty(), krb_err_txt[kerno]); 421 dest_tkt(); 422 return (1); 423 } 424 } 425 return (0); 426 } 427 428 static int 429 koktologin(name, realm, toname) 430 char *name, *realm, *toname; 431 { 432 register AUTH_DAT *kdata; 433 AUTH_DAT kdata_st; 434 435 kdata = &kdata_st; 436 memset((char *)kdata, 0, sizeof(*kdata)); 437 (void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1); 438 (void)strncpy(kdata->pinst, 439 ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1); 440 (void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1); 441 return (kuserok(kdata, toname)); 442 } 443 #endif 444
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