su.c revision 1.73
1 /* $NetBSD: su.c,v 1.73 2021/10/17 10:33:57 nia 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. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __COPYRIGHT("@(#) Copyright (c) 1988\ 35 The Regents of the University of California. All rights reserved."); 36 #endif /* not lint */ 37 38 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/ 41 #else 42 __RCSID("$NetBSD: su.c,v 1.73 2021/10/17 10:33:57 nia Exp $"); 43 #endif 44 #endif /* not lint */ 45 46 #include <sys/param.h> 47 #include <sys/time.h> 48 #include <sys/resource.h> 49 #include <err.h> 50 #include <errno.h> 51 #include <grp.h> 52 #include <paths.h> 53 #include <pwd.h> 54 #include <stdio.h> 55 #ifdef SKEY 56 #include <skey.h> 57 #endif 58 #include <stdlib.h> 59 #include <string.h> 60 #include <syslog.h> 61 #include <time.h> 62 #include <tzfile.h> 63 #include <unistd.h> 64 #include <util.h> 65 66 #ifdef LOGIN_CAP 67 #include <login_cap.h> 68 #endif 69 70 #ifdef KERBEROS5 71 #include <krb5.h> 72 #endif 73 74 #ifdef ALLOW_GROUP_CHANGE 75 #include "grutil.h" 76 #endif 77 #include "suutil.h" 78 79 #ifdef KERBEROS5 80 #define ARGSTRX "-Kdflm" 81 static int kerberos5(char *, const char *, uid_t); 82 int use_kerberos = 1; 83 #else 84 #define ARGSTRX "-dflm" 85 #endif 86 87 #ifndef SU_GROUP 88 #define SU_GROUP "wheel" 89 #endif 90 91 #define GROUP_PASSWORD "Group Password:" 92 93 #ifdef LOGIN_CAP 94 #define ARGSTR ARGSTRX "c:" 95 #else 96 #define ARGSTR ARGSTRX 97 #endif 98 99 static int check_ingroup(int, const char *, const char *, int); 100 101 int 102 main(int argc, char **argv) 103 { 104 extern char **environ; 105 struct passwd *pwd; 106 char *p; 107 #ifdef BSD4_4 108 struct timeval tp; 109 #endif 110 uid_t ruid; 111 int asme, ch, asthem, fastlogin, prio, gohome; 112 enum { UNSET, YES, NO } iscsh = UNSET; 113 const char *user, *shell, *avshell; 114 char *username, **np; 115 #ifdef SU_ROOTAUTH 116 char *userpass; 117 #endif 118 char *class; 119 char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN]; 120 time_t pw_warntime = _PASSWORD_WARNDAYS * SECSPERDAY; 121 #ifdef LOGIN_CAP 122 login_cap_t *lc; 123 #endif 124 #ifdef ALLOW_GROUP_CHANGE 125 char *gname; 126 #endif 127 128 (void)setprogname(argv[0]); 129 asme = asthem = fastlogin = 0; 130 gohome = 1; 131 shell = class = NULL; 132 while ((ch = getopt(argc, argv, ARGSTR)) != -1) 133 switch((char)ch) { 134 #ifdef KERBEROS5 135 case 'K': 136 use_kerberos = 0; 137 break; 138 #endif 139 #ifdef LOGIN_CAP 140 case 'c': 141 class = optarg; 142 break; 143 #endif 144 case 'd': 145 asme = 0; 146 asthem = 1; 147 gohome = 0; 148 break; 149 case 'f': 150 fastlogin = 1; 151 break; 152 case '-': 153 case 'l': 154 asme = 0; 155 asthem = 1; 156 break; 157 case 'm': 158 asme = 1; 159 asthem = 0; 160 break; 161 case '?': 162 default: 163 (void)fprintf(stderr, 164 #ifdef ALLOW_GROUP_CHANGE 165 "usage: %s [%s] [login[:group] [shell arguments]]\n", 166 #else 167 "usage: %s [%s] [login [shell arguments]]\n", 168 #endif 169 getprogname(), ARGSTR); 170 exit(EXIT_FAILURE); 171 } 172 argv += optind; 173 174 /* Lower the priority so su runs faster */ 175 errno = 0; 176 prio = getpriority(PRIO_PROCESS, 0); 177 if (errno) 178 prio = 0; 179 if (prio > -2) 180 (void)setpriority(PRIO_PROCESS, 0, -2); 181 openlog("su", 0, LOG_AUTH); 182 183 /* get current login name and shell */ 184 ruid = getuid(); 185 username = getlogin(); 186 if (username == NULL || (pwd = getpwnam(username)) == NULL || 187 pwd->pw_uid != ruid) 188 pwd = getpwuid(ruid); 189 if (pwd == NULL) 190 errx(EXIT_FAILURE, "who are you?"); 191 username = estrdup(pwd->pw_name); 192 #ifdef SU_ROOTAUTH 193 userpass = estrdup(pwd->pw_passwd); 194 #endif 195 196 if (asme) { 197 if (pwd->pw_shell && *pwd->pw_shell) { 198 (void)estrlcpy(shellbuf, pwd->pw_shell, sizeof(shellbuf)); 199 shell = shellbuf; 200 } else { 201 shell = _PATH_BSHELL; 202 iscsh = NO; 203 } 204 } 205 /* get target login information, default to root */ 206 user = *argv ? *argv : "root"; 207 np = *argv ? argv : argv - 1; 208 209 #ifdef ALLOW_GROUP_CHANGE 210 if ((p = strchr(user, ':')) != NULL) { 211 *p = '\0'; 212 gname = ++p; 213 } 214 else 215 gname = NULL; 216 217 #ifdef ALLOW_EMPTY_USER 218 if (user[0] == '\0' && gname != NULL) 219 user = username; 220 #endif 221 #endif 222 if ((pwd = getpwnam(user)) == NULL) 223 errx(EXIT_FAILURE, "unknown login `%s'", user); 224 225 #ifdef LOGIN_CAP 226 /* force the usage of specified class */ 227 if (class) { 228 if (ruid) 229 errx(EXIT_FAILURE, "Only root may use -c"); 230 231 pwd->pw_class = class; 232 } 233 if ((lc = login_getclass(pwd->pw_class)) == NULL) 234 errx(EXIT_FAILURE, "Unknown class %s", pwd->pw_class); 235 236 pw_warntime = (time_t)login_getcaptime(lc, "password-warn", 237 _PASSWORD_WARNDAYS * SECSPERDAY, 238 _PASSWORD_WARNDAYS * SECSPERDAY); 239 #endif 240 241 if (ruid 242 #ifdef KERBEROS5 243 && (!use_kerberos || kerberos5(username, user, pwd->pw_uid)) 244 #endif 245 ) { 246 char *pass = pwd->pw_passwd; 247 int ok = pwd->pw_uid != 0; 248 249 #ifdef SU_ROOTAUTH 250 /* 251 * Allow those in group rootauth to su to root, by supplying 252 * their own password. 253 */ 254 if (!ok) { 255 if ((ok = check_ingroup(-1, SU_ROOTAUTH, username, 0))) { 256 pass = userpass; 257 user = username; 258 } 259 } 260 #endif 261 /* 262 * Only allow those in group SU_GROUP to su to root, 263 * but only if that group has any members. 264 * If SU_GROUP has no members, allow anyone to su root 265 */ 266 if (!ok) 267 ok = check_ingroup(-1, SU_GROUP, username, 1); 268 if (!ok) 269 errx(EXIT_FAILURE, 270 "you are not listed in the correct secondary group (%s) to su %s.", 271 SU_GROUP, user); 272 /* if target requires a password, verify it */ 273 if (*pass && pwd->pw_uid != ruid) { /* XXX - OK? */ 274 p = getpass("Password:"); 275 #ifdef SKEY 276 if (strcasecmp(p, "s/key") == 0) { 277 if (skey_haskey(user)) 278 errx(EXIT_FAILURE, 279 "Sorry, you have no s/key."); 280 else { 281 if (skey_authenticate(user)) { 282 goto badlogin; 283 } 284 } 285 286 } else 287 #endif 288 if (consttime_memequal(pass, 289 crypt(p, pass), strlen(pass)) == 0) { 290 #ifdef SKEY 291 badlogin: 292 #endif 293 (void)fprintf(stderr, "Sorry\n"); 294 syslog(LOG_WARNING, 295 "BAD SU %s to %s%s", username, 296 pwd->pw_name, ontty()); 297 exit(EXIT_FAILURE); 298 } 299 } 300 } 301 302 if (asme) { 303 /* if asme and non-standard target shell, must be root */ 304 if (chshell(pwd->pw_shell) == 0 && ruid) 305 errx(EXIT_FAILURE, "permission denied (shell)."); 306 } else if (pwd->pw_shell && *pwd->pw_shell) { 307 shell = pwd->pw_shell; 308 iscsh = UNSET; 309 } else { 310 shell = _PATH_BSHELL; 311 iscsh = NO; 312 } 313 314 if ((p = strrchr(shell, '/')) != NULL) 315 avshell = p+1; 316 else 317 avshell = shell; 318 319 /* if we're forking a csh, we want to slightly muck the args */ 320 if (iscsh == UNSET) 321 iscsh = strstr(avshell, "csh") ? YES : NO; 322 323 /* set permissions */ 324 #ifdef LOGIN_CAP 325 # ifdef ALLOW_GROUP_CHANGE 326 /* if we aren't changing users, keep the current group members */ 327 if (ruid != pwd->pw_uid && 328 setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) == -1) 329 err(EXIT_FAILURE, "setting user context"); 330 331 addgroup(lc, gname, pwd, ruid, GROUP_PASSWORD); 332 333 if (setusercontext(lc, pwd, pwd->pw_uid, 334 (u_int)(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) | 335 LOGIN_SETRESOURCES | LOGIN_SETUSER) == -1) 336 err(EXIT_FAILURE, "setting user context"); 337 # else 338 if (setusercontext(lc, pwd, pwd->pw_uid, 339 (u_int)(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) | 340 LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER) == -1) 341 err(EXIT_FAILURE, "setting user context"); 342 # endif 343 #else 344 if (setgid(pwd->pw_gid) == -1) 345 err(EXIT_FAILURE, "setgid"); 346 /* if we aren't changing users, keep the current group members */ 347 if (ruid != pwd->pw_uid && initgroups(user, pwd->pw_gid) != 0) 348 errx(EXIT_FAILURE, "initgroups failed"); 349 # ifdef ALLOW_GROUP_CHANGE 350 addgroup(/*EMPTY*/, gname, pwd, ruid, GROUP_PASSWORD); 351 # endif 352 if (setuid(pwd->pw_uid) == -1) 353 err(EXIT_FAILURE, "setuid"); 354 #endif 355 356 if (!asme) { 357 if (asthem) { 358 p = getenv("TERM"); 359 /* Create an empty environment */ 360 environ = emalloc(sizeof(char *)); 361 environ[0] = NULL; 362 #ifdef LOGIN_CAP 363 if (setusercontext(lc, pwd, pwd->pw_uid, 364 LOGIN_SETPATH) == -1) 365 err(EXIT_FAILURE, "setting user context"); 366 #else 367 (void)setenv("PATH", _PATH_DEFPATH, 1); 368 #endif 369 if (p) 370 (void)setenv("TERM", p, 1); 371 if (gohome && chdir(pwd->pw_dir) == -1) 372 errx(EXIT_FAILURE, "no directory"); 373 } 374 375 if (asthem || pwd->pw_uid) { 376 (void)setenv("LOGNAME", pwd->pw_name, 1); 377 (void)setenv("USER", pwd->pw_name, 1); 378 } 379 (void)setenv("HOME", pwd->pw_dir, 1); 380 (void)setenv("SHELL", shell, 1); 381 } 382 (void)setenv("SU_FROM", username, 1); 383 384 if (iscsh == YES) { 385 if (fastlogin) 386 *np-- = __UNCONST("-f"); 387 if (asme) 388 *np-- = __UNCONST("-m"); 389 } else { 390 if (fastlogin) 391 (void)unsetenv("ENV"); 392 } 393 394 if (asthem) { 395 avshellbuf[0] = '-'; 396 (void)estrlcpy(avshellbuf + 1, avshell, sizeof(avshellbuf) - 1); 397 avshell = avshellbuf; 398 } else if (iscsh == YES) { 399 /* csh strips the first character... */ 400 avshellbuf[0] = '_'; 401 (void)estrlcpy(avshellbuf + 1, avshell, sizeof(avshellbuf) - 1); 402 avshell = avshellbuf; 403 } 404 *np = __UNCONST(avshell); 405 406 #ifdef BSD4_4 407 if (pwd->pw_change || pwd->pw_expire) 408 (void)gettimeofday(&tp, NULL); 409 if (pwd->pw_change) { 410 if (tp.tv_sec >= pwd->pw_change) { 411 (void)printf("%s -- %s's password has expired.\n", 412 (ruid ? "Sorry" : "Note"), user); 413 if (ruid != 0) 414 exit(EXIT_FAILURE); 415 } else if (pwd->pw_change - tp.tv_sec < pw_warntime) 416 (void)printf("Warning: %s's password expires on %s", 417 user, ctime(&pwd->pw_change)); 418 } 419 if (pwd->pw_expire) { 420 if (tp.tv_sec >= pwd->pw_expire) { 421 (void)printf("%s -- %s's account has expired.\n", 422 (ruid ? "Sorry" : "Note"), user); 423 if (ruid != 0) 424 exit(EXIT_FAILURE); 425 } else if (pwd->pw_expire - tp.tv_sec < 426 _PASSWORD_WARNDAYS * SECSPERDAY) 427 (void)printf("Warning: %s's account expires on %s", 428 user, ctime(&pwd->pw_expire)); 429 } 430 #endif 431 if (ruid != 0) 432 syslog(LOG_NOTICE, "%s to %s%s", 433 username, pwd->pw_name, ontty()); 434 435 /* Raise our priority back to what we had before */ 436 (void)setpriority(PRIO_PROCESS, 0, prio); 437 438 (void)execv(shell, np); 439 err(EXIT_FAILURE, "%s", shell); 440 /* NOTREACHED */ 441 } 442 443 444 #ifdef KERBEROS5 445 static int 446 kerberos5(char *username, const char *user, uid_t uid) 447 { 448 krb5_error_code ret; 449 krb5_context context; 450 krb5_principal princ = NULL; 451 krb5_ccache ccache, ccache2; 452 char *cc_name; 453 const char *filename; 454 455 ret = krb5_init_context(&context); 456 if (ret) 457 return 1; 458 459 if (strcmp(user, "root") == 0) 460 ret = krb5_make_principal(context, &princ, 461 NULL, username, "root", NULL); 462 else 463 ret = krb5_make_principal(context, &princ, 464 NULL, user, NULL); 465 if (ret) 466 goto fail; 467 if (!krb5_kuserok(context, princ, user) && !uid) { 468 warnx("kerberos5: not in %s's ACL.", user); 469 goto fail; 470 } 471 ret = krb5_cc_new_unique(context, krb5_mcc_ops.prefix, NULL, &ccache); 472 if (ret) 473 goto fail; 474 ret = krb5_verify_user_lrealm(context, princ, ccache, NULL, TRUE, 475 NULL); 476 if (ret) { 477 krb5_cc_destroy(context, ccache); 478 switch (ret) { 479 case KRB5_LIBOS_PWDINTR : 480 break; 481 case KRB5KRB_AP_ERR_BAD_INTEGRITY: 482 case KRB5KRB_AP_ERR_MODIFIED: 483 krb5_warnx(context, "Password incorrect"); 484 break; 485 default : 486 krb5_warn(context, ret, "krb5_verify_user"); 487 break; 488 } 489 goto fail; 490 } 491 ret = krb5_cc_new_unique(context, krb5_mcc_ops.prefix, NULL, &ccache2); 492 if (ret) { 493 krb5_cc_destroy(context, ccache); 494 goto fail; 495 } 496 ret = krb5_cc_copy_cache(context, ccache, ccache2); 497 if (ret) { 498 krb5_cc_destroy(context, ccache); 499 krb5_cc_destroy(context, ccache2); 500 goto fail; 501 } 502 503 filename = krb5_cc_get_name(context, ccache2); 504 (void)easprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2), 505 filename); 506 if (chown(filename, uid, NOGROUP) == -1) { 507 warn("chown %s", filename); 508 free(cc_name); 509 krb5_cc_destroy(context, ccache); 510 krb5_cc_destroy(context, ccache2); 511 goto fail; 512 } 513 514 (void)setenv("KRB5CCNAME", cc_name, 1); 515 free(cc_name); 516 krb5_cc_close(context, ccache2); 517 krb5_cc_destroy(context, ccache); 518 return 0; 519 520 fail: 521 if (princ != NULL) 522 krb5_free_principal(context, princ); 523 krb5_free_context(context); 524 return 1; 525 } 526 #endif /* KERBEROS5 */ 527 528 static int 529 check_ingroup(int gid, const char *gname, const char *user, int ifempty) 530 { 531 struct group *gr; 532 char **g; 533 #ifdef SU_INDIRECT_GROUP 534 char **gr_mem; 535 int n = 0; 536 int i = 0; 537 #endif 538 int ok = 0; 539 540 if (gname == NULL) 541 gr = getgrgid((gid_t) gid); 542 else 543 gr = getgrnam(gname); 544 545 /* 546 * XXX we are relying on the fact that we only set ifempty when 547 * calling to check for SU_GROUP and that is the only time a 548 * missing group is acceptable. 549 */ 550 if (gr == NULL) 551 return ifempty; 552 if (!*gr->gr_mem) /* empty */ 553 return ifempty; 554 555 /* 556 * Ok, first see if user is in gr_mem 557 */ 558 for (g = gr->gr_mem; *g; ++g) { 559 if (strcmp(*g, user) == 0) 560 return 1; /* ok */ 561 #ifdef SU_INDIRECT_GROUP 562 ++n; /* count them */ 563 #endif 564 } 565 #ifdef SU_INDIRECT_GROUP 566 /* 567 * No. 568 * Now we need to duplicate the gr_mem list, and recurse for 569 * each member to see if it is a group, and if so whether user is 570 * in it. 571 */ 572 gr_mem = emalloc((n + 1) * sizeof (char *)); 573 for (g = gr->gr_mem, i = 0; *g; ++g) { 574 gr_mem[i] = estrdup(*g); 575 i++; 576 } 577 gr_mem[i++] = NULL; 578 579 for (g = gr_mem; ok == 0 && *g; ++g) { 580 /* 581 * If we get this far we don't accept empty/missing groups. 582 */ 583 ok = check_ingroup(-1, *g, user, 0); 584 } 585 for (g = gr_mem; *g; ++g) { 586 free(*g); 587 } 588 free(gr_mem); 589 #endif 590 return ok; 591 } 592
Indexes created Thu Oct 30 03:10:01 GMT 2025