k5login.c revision 1.26
1 /* $NetBSD: k5login.c,v 1.26 2005/01/20 15:41:14 xtraeme Exp $ */ 2 3 /*- 4 * Copyright (c) 1990 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 /* 33 * Copyright (c) 1980, 1987, 1988 The Regents of the University of California. 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms are permitted 37 * provided that the above copyright notice and this paragraph are 38 * duplicated in all such forms and that any documentation, 39 * advertising materials, and other materials related to such 40 * distribution and use acknowledge that the software was developed 41 * by the University of California, Berkeley. The name of the 42 * University may not be used to endorse or promote products derived 43 * from this software without specific prior written permission. 44 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 45 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 46 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 47 */ 48 49 #include <sys/cdefs.h> 50 #ifndef lint 51 #if 0 52 static char sccsid[] = "@(#)klogin.c 5.11 (Berkeley) 7/12/92"; 53 #endif 54 __RCSID("$NetBSD: k5login.c,v 1.26 2005/01/20 15:41:14 xtraeme Exp $"); 55 #endif /* not lint */ 56 57 #ifdef KERBEROS5 58 #include <sys/param.h> 59 #include <sys/syslog.h> 60 #include <krb5/krb5.h> 61 #ifdef KERBEROS 62 #include <kerberosIV/krb.h> 63 #endif 64 #include <pwd.h> 65 #include <netdb.h> 66 #include <stdio.h> 67 #include <stdlib.h> 68 #include <string.h> 69 #include <unistd.h> 70 #include <errno.h> 71 72 #define KRB5_DEFAULT_OPTIONS 0 73 #define KRB5_DEFAULT_LIFE 60*60*10 /* 10 hours */ 74 75 krb5_context kcontext; 76 77 int notickets; 78 int krb5_configured; 79 char *krb5tkfile_env; 80 extern char *tty; 81 extern int login_krb5_forwardable_tgt; 82 extern int has_ccache; 83 84 static char tkt_location[MAXPATHLEN]; 85 #ifdef KERBEROS 86 char krb4tkfile[MAXPATHLEN]; 87 #endif 88 static krb5_creds forw_creds; 89 int have_forward; 90 static krb5_principal me, server; 91 92 int k5_read_creds(char *); 93 int k5_write_creds(void); 94 int k5_verify_creds(krb5_context, krb5_ccache); 95 int k5login(struct passwd *, char *, char *, char *); 96 void k5destroy(void); 97 98 #ifdef KERBEROS 99 static krb5_error_code 100 krb5_to4 (struct passwd *pw, krb5_context context, krb5_ccache id); 101 #endif 102 103 #ifndef krb5_realm_length 104 #define krb5_realm_length(r) ((r).length) 105 #endif 106 #ifndef krb5_realm_data 107 #define krb5_realm_data(r) ((r).data) 108 #endif 109 110 /* 111 * Verify the Kerberos ticket-granting ticket just retrieved for the 112 * user. If the Kerberos server doesn't respond, assume the user is 113 * trying to fake us out (since we DID just get a TGT from what is 114 * supposedly our KDC). If the host/<host> service is unknown (i.e., 115 * the local keytab doesn't have it), let her in. 116 * 117 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 118 */ 119 int 120 k5_verify_creds(krb5_context c, krb5_ccache ccache) 121 { 122 char phost[MAXHOSTNAMELEN]; 123 int retval, have_keys; 124 krb5_principal princ; 125 krb5_keyblock *kb = 0; 126 krb5_error_code kerror; 127 krb5_data packet; 128 krb5_auth_context auth_context = NULL; 129 krb5_ticket *ticket = NULL; 130 131 kerror = krb5_sname_to_principal(c, 0, 0, KRB5_NT_SRV_HST, &princ); 132 if (kerror) { 133 krb5_warn(kcontext, kerror, "constructing local service name"); 134 return (-1); 135 } 136 137 /* Do we have host/<host> keys? */ 138 /* (use default keytab, kvno IGNORE_VNO to get the first match, 139 * and default enctype.) */ 140 kerror = krb5_kt_read_service_key(c, NULL, princ, 0, 0, &kb); 141 if (kb) 142 krb5_free_keyblock(c, kb); 143 /* any failure means we don't have keys at all. */ 144 have_keys = kerror ? 0 : 1; 145 146 /* XXX there should be a krb5 function like mk_req, but taking a full 147 * principal, instead of a service/hostname. (Did I miss one?) */ 148 gethostname(phost, sizeof(phost)); 149 phost[sizeof(phost) - 1] = '\0'; 150 151 /* talk to the kdc and construct the ticket */ 152 kerror = krb5_mk_req(c, &auth_context, 0, "host", phost, 153 0, ccache, &packet); 154 /* wipe the auth context for rd_req */ 155 if (auth_context) { 156 krb5_auth_con_free(c, auth_context); 157 auth_context = NULL; 158 } 159 if (kerror == KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN) { 160 /* we have a service key, so something should be 161 * in the database, therefore this error packet could 162 * have come from an attacker. */ 163 if (have_keys) { 164 retval = -1; 165 goto EGRESS; 166 } 167 /* but if it is unknown and we've got no key, we don't 168 * have any security anyhow, so it is ok. */ 169 else { 170 retval = 0; 171 goto EGRESS; 172 } 173 } 174 else if (kerror) { 175 krb5_warn(kcontext, kerror, 176 "Unable to verify Kerberos V5 TGT: %s", phost); 177 syslog(LOG_NOTICE, "Kerberos V5 TGT bad: %s", 178 krb5_get_err_text(kcontext, kerror)); 179 retval = -1; 180 goto EGRESS; 181 } 182 /* got ticket, try to use it */ 183 kerror = krb5_rd_req(c, &auth_context, &packet, 184 princ, NULL, NULL, &ticket); 185 if (kerror) { 186 if (!have_keys) { 187 /* The krb5 errors aren't specified well, but I think 188 * these values cover the cases we expect. */ 189 switch (kerror) { 190 case ENOENT: /* no keytab */ 191 case KRB5_KT_NOTFOUND: 192 retval = 0; 193 break; 194 default: 195 /* unexpected error: fail */ 196 retval = -1; 197 break; 198 } 199 } 200 else { 201 /* we have keys, so if we got any error, we could be 202 * under attack. */ 203 retval = -1; 204 } 205 krb5_warn(kcontext, kerror, "Unable to verify host ticket"); 206 syslog(LOG_NOTICE, "can't verify v5 ticket: %s; %s\n", 207 krb5_get_err_text(kcontext, kerror), 208 retval 209 ? "keytab found, assuming failure" 210 : "no keytab found, assuming success"); 211 goto EGRESS; 212 } 213 /* 214 * The host/<host> ticket has been received _and_ verified. 215 */ 216 retval = 1; 217 218 /* do cleanup and return */ 219 EGRESS: 220 if (auth_context) 221 krb5_auth_con_free(c, auth_context); 222 krb5_free_principal(c, princ); 223 /* possibly ticket and packet need freeing here as well */ 224 return (retval); 225 } 226 227 /* 228 * Attempt to read forwarded kerberos creds 229 * 230 * return 0 on success (forwarded creds in memory) 231 * 1 if no forwarded creds. 232 */ 233 int 234 k5_read_creds(char *username) 235 { 236 krb5_error_code kerror; 237 krb5_creds mcreds; 238 krb5_ccache ccache; 239 240 have_forward = 0; 241 memset((char*) &mcreds, 0, sizeof(forw_creds)); 242 memset((char*) &forw_creds, 0, sizeof(forw_creds)); 243 244 kerror = krb5_cc_default(kcontext, &ccache); 245 if (kerror) { 246 krb5_warn(kcontext, kerror, "while getting default ccache"); 247 return(1); 248 } 249 250 kerror = krb5_parse_name(kcontext, username, &me); 251 if (kerror) { 252 krb5_warn(kcontext, kerror, "when parsing name %s", username); 253 return(1); 254 } 255 256 mcreds.client = me; 257 kerror = krb5_build_principal_ext(kcontext, &mcreds.server, 258 krb5_realm_length(*krb5_princ_realm(kcontext, me)), 259 krb5_realm_data(*krb5_princ_realm(kcontext, me)), 260 KRB5_TGS_NAME_SIZE, 261 KRB5_TGS_NAME, 262 krb5_realm_length(*krb5_princ_realm(kcontext, me)), 263 krb5_realm_data(*krb5_princ_realm(kcontext, me)), 264 0); 265 if (kerror) { 266 krb5_warn(kcontext, kerror, "while building server name"); 267 goto nuke_ccache; 268 } 269 270 kerror = krb5_cc_retrieve_cred(kcontext, ccache, 0, 271 &mcreds, &forw_creds); 272 if (kerror) { 273 krb5_warn(kcontext, kerror, 274 "while retrieving V5 initial ticket for copy"); 275 goto nuke_ccache; 276 } 277 278 have_forward = 1; 279 280 strlcpy(tkt_location, getenv("KRB5CCNAME"), sizeof(tkt_location)); 281 krb5tkfile_env = tkt_location; 282 has_ccache = 1; 283 notickets = 0; 284 285 nuke_ccache: 286 krb5_cc_destroy(kcontext, ccache); 287 return(!have_forward); 288 } 289 290 int 291 k5_write_creds(void) 292 { 293 krb5_error_code kerror; 294 krb5_ccache ccache; 295 296 if (!have_forward) 297 return (1); 298 299 kerror = krb5_cc_default(kcontext, &ccache); 300 if (kerror) { 301 krb5_warn(kcontext, kerror, "while getting default ccache"); 302 return (1); 303 } 304 305 kerror = krb5_cc_initialize(kcontext, ccache, me); 306 if (kerror) { 307 krb5_warn(kcontext, kerror, 308 "while re-initializing V5 ccache as user"); 309 goto nuke_ccache_contents; 310 } 311 312 kerror = krb5_cc_store_cred(kcontext, ccache, &forw_creds); 313 if (kerror) { 314 krb5_warn(kcontext, kerror, 315 "while re-storing V5 ccache as user"); 316 goto nuke_ccache_contents; 317 } 318 319 nuke_ccache_contents: 320 krb5_free_cred_contents(kcontext, &forw_creds); 321 return (kerror != 0); 322 } 323 324 /* 325 * Get krb4 credentials if needed 326 */ 327 #ifdef KERBEROS 328 static krb5_error_code 329 krb5_to4 (struct passwd *pw, krb5_context context, krb5_ccache id) 330 { 331 if (krb5_config_get_bool(context, NULL, 332 "libdefaults", 333 "krb4_get_tickets", 334 NULL)) { 335 CREDENTIALS c; 336 krb5_creds mcred, cred; 337 krb5_error_code ret; 338 krb5_principal princ; 339 340 ret = krb5_cc_get_principal (context, id, &princ); 341 if (ret) 342 return ret; 343 344 ret = krb5_make_principal(context, &mcred.server, 345 princ->realm, 346 "krbtgt", 347 princ->realm, 348 NULL); 349 krb5_free_principal (context, princ); 350 if (ret) 351 return ret; 352 353 ret = krb5_cc_retrieve_cred(context, id, 0, &mcred, &cred); 354 if(ret == 0) { 355 ret = krb524_convert_creds_kdc_ccache(context, id, 356 &cred, &c); 357 if(ret == 0) { 358 snprintf(krb4tkfile, sizeof(krb4tkfile), 359 "%s%d",TKT_ROOT, pw->pw_uid); 360 krb_set_tkt_string(krb4tkfile); 361 tf_setup(&c, c.pname, c.pinst); 362 if (chown(krb4tkfile, pw->pw_uid, 363 pw->pw_gid) < 0) 364 syslog(LOG_ERR, 365 "chown tkfile (%s): %m", 366 krb4tkfile); 367 } 368 memset(&c, 0, sizeof(c)); 369 krb5_free_creds_contents(context, &cred); 370 } 371 krb5_free_principal(context, mcred.server); 372 } 373 return 0; 374 } 375 #endif /* KERBEROS */ 376 377 /* 378 * Attempt to log the user in using Kerberos authentication 379 * 380 * return 0 on success (will be logged in) 381 * 1 if Kerberos failed (try local password in login) 382 */ 383 int 384 k5login(struct passwd *pw, char *instance, char *localhost, char *password) 385 { 386 krb5_error_code kerror; 387 krb5_creds my_creds; 388 krb5_timestamp now; 389 krb5_ccache ccache = NULL; 390 long lifetime = KRB5_DEFAULT_LIFE; 391 int options = KRB5_DEFAULT_OPTIONS; 392 char *realm, *client_name; 393 char *principal; 394 395 krb5_configured = 1; 396 397 if (login_krb5_forwardable_tgt) 398 options |= KDC_OPT_FORWARDABLE; 399 400 /* 401 * Root logins don't use Kerberos. 402 * If we have a realm, try getting a ticket-granting ticket 403 * and using it to authenticate. Otherwise, return 404 * failure so that we can try the normal passwd file 405 * for a password. If that's ok, log the user in 406 * without issuing any tickets. 407 */ 408 if (strcmp(pw->pw_name, "root") == 0 || 409 krb5_get_default_realm(kcontext, &realm)) { 410 krb5_configured = 0; 411 return (1); 412 } 413 414 /* 415 * get TGT for local realm 416 * tickets are stored in a file named TKT_ROOT plus uid 417 * except for user.root tickets. 418 */ 419 420 if (strcmp(instance, "root") != 0) 421 (void)snprintf(tkt_location, sizeof tkt_location, 422 "FILE:/tmp/krb5cc_%d.%s", pw->pw_uid, tty); 423 else 424 (void)snprintf(tkt_location, sizeof tkt_location, 425 "FILE:/tmp/krb5cc_root_%d.%s", pw->pw_uid, tty); 426 krb5tkfile_env = tkt_location; 427 has_ccache = 1; 428 429 if (strlen(instance)) 430 asprintf(&principal, "%s/%s", pw->pw_name, instance); 431 else 432 principal = strdup(pw->pw_name); 433 if (!principal) { 434 syslog(LOG_NOTICE, "fatal: %s", strerror(errno)); 435 return (1); 436 } 437 438 if ((kerror = krb5_cc_resolve(kcontext, tkt_location, &ccache)) != 0) { 439 syslog(LOG_NOTICE, "warning: %s while getting default ccache", 440 krb5_get_err_text(kcontext, kerror)); 441 return (1); 442 } 443 444 if ((kerror = krb5_parse_name(kcontext, principal, &me)) != 0) { 445 syslog(LOG_NOTICE, "warning: %s when parsing name %s", 446 krb5_get_err_text(kcontext, kerror), principal); 447 return (1); 448 } 449 450 if ((kerror = krb5_unparse_name(kcontext, me, &client_name)) != 0) { 451 syslog(LOG_NOTICE, "warning: %s when unparsing name %s", 452 krb5_get_err_text(kcontext, kerror), principal); 453 return (1); 454 } 455 456 kerror = krb5_cc_initialize(kcontext, ccache, me); 457 if (kerror != 0) { 458 syslog(LOG_NOTICE, "%s when initializing cache %s", 459 krb5_get_err_text(kcontext, kerror), tkt_location); 460 return (1); 461 } 462 463 memset((char *)&my_creds, 0, sizeof(my_creds)); 464 465 my_creds.client = me; 466 467 if ((kerror = krb5_build_principal_ext(kcontext, 468 &server, 469 krb5_realm_length(*krb5_princ_realm(kcontext, me)), 470 krb5_realm_data(*krb5_princ_realm(kcontext, me)), 471 KRB5_TGS_NAME_SIZE, 472 KRB5_TGS_NAME, 473 krb5_realm_length(*krb5_princ_realm(kcontext, me)), 474 krb5_realm_data(*krb5_princ_realm(kcontext, me)), 475 0)) != 0) { 476 syslog(LOG_NOTICE, "%s while building server name", 477 krb5_get_err_text(kcontext, kerror)); 478 return (1); 479 } 480 481 my_creds.server = server; 482 483 if ((kerror = krb5_timeofday(kcontext, &now)) != 0) { 484 syslog(LOG_NOTICE, "%s while getting time of day", 485 krb5_get_err_text(kcontext, kerror)); 486 return (1); 487 } 488 489 my_creds.times.starttime = 0; /* start timer when request 490 gets to KDC */ 491 my_creds.times.endtime = now + lifetime; 492 my_creds.times.renew_till = 0; 493 494 kerror = krb5_get_in_tkt_with_password(kcontext, options, 495 NULL, 496 NULL, 497 NULL, 498 password, 499 ccache, 500 &my_creds, 0); 501 502 if (my_creds.server != NULL) 503 krb5_free_principal(kcontext, my_creds.server); 504 505 if (chown(&tkt_location[5], pw->pw_uid, pw->pw_gid) < 0) 506 syslog(LOG_ERR, "chown tkfile (%s): %m", &tkt_location[5]); 507 508 if (kerror) { 509 if (kerror == KRB5KRB_AP_ERR_BAD_INTEGRITY) 510 printf("%s: Kerberos Password incorrect\n", principal); 511 else 512 krb5_warn(kcontext, kerror, 513 "while getting initial credentials"); 514 515 return (1); 516 } 517 518 if (k5_verify_creds(kcontext, ccache) < 0) 519 return (1); 520 521 #ifdef KERBEROS 522 if ((kerror = krb5_to4(pw, kcontext, ccache)) != 0) 523 krb5_warn(kcontext, kerror, "error converting krb4 creds"); 524 #endif 525 526 /* Success */ 527 notickets = 0; 528 return (0); 529 } 530 531 /* 532 * Remove any credentials 533 */ 534 void 535 k5destroy(void) 536 { 537 krb5_error_code kerror; 538 krb5_ccache ccache = NULL; 539 540 if (krb5tkfile_env == NULL) 541 return; 542 543 kerror = krb5_cc_resolve(kcontext, krb5tkfile_env, &ccache); 544 if (kerror == 0) 545 (void)krb5_cc_destroy(kcontext, ccache); 546 } 547 #endif /* KERBEROS5 */ 548
Indexes created Thu Sep 25 16:09:42 GMT 2025