pam_krb5.c revision 1.4
1 /* $NetBSD: pam_krb5.c,v 1.4 2005/02/26 18:03:37 thorpej Exp $ */ 2 3 /*- 4 * This pam_krb5 module contains code that is: 5 * Copyright (c) Derrick J. Brashear, 1996. All rights reserved. 6 * Copyright (c) Frank Cusack, 1999-2001. All rights reserved. 7 * Copyright (c) Jacques A. Vidrine, 2000-2001. All rights reserved. 8 * Copyright (c) Nicolas Williams, 2001. All rights reserved. 9 * Copyright (c) Perot Systems Corporation, 2001. All rights reserved. 10 * Copyright (c) Mark R V Murray, 2001. All rights reserved. 11 * Copyright (c) Networks Associates Technology, Inc., 2002-2005. 12 * All rights reserved. 13 * 14 * Portions of this software were developed for the FreeBSD Project by 15 * ThinkSec AS and NAI Labs, the Security Research Division of Network 16 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 17 * ("CBOSS"), as part of the DARPA CHATS research program. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notices, and the entire permission notice in its entirety, 24 * including the disclaimer of warranties. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 3. The name of the author may not be used to endorse or promote 29 * products derived from this software without specific prior 30 * written permission. 31 * 32 * ALTERNATIVELY, this product may be distributed under the terms of 33 * the GNU Public License, in which case the provisions of the GPL are 34 * required INSTEAD OF the above restrictions. (This clause is 35 * necessary due to a potential bad interaction between the GPL and 36 * the restrictions contained in a BSD-style copyright.) 37 * 38 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED 39 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 40 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 41 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, 42 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 43 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 44 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 46 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 47 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 48 * OF THE POSSIBILITY OF SUCH DAMAGE. 49 * 50 */ 51 52 #include <sys/cdefs.h> 53 #ifdef __FreeBSD__ 54 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_krb5/pam_krb5.c,v 1.22 2005/01/24 16:49:50 rwatson Exp $"); 55 #else 56 __RCSID("$NetBSD: pam_krb5.c,v 1.4 2005/02/26 18:03:37 thorpej Exp $"); 57 #endif 58 59 #include <sys/types.h> 60 #include <sys/stat.h> 61 #include <errno.h> 62 #include <limits.h> 63 #include <pwd.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <syslog.h> 68 #include <unistd.h> 69 70 #include <krb5/krb5.h> 71 #include <krb5/com_err.h> 72 73 #define PAM_SM_AUTH 74 #define PAM_SM_ACCOUNT 75 #define PAM_SM_PASSWORD 76 77 #include <security/pam_appl.h> 78 #include <security/pam_modules.h> 79 #include <security/pam_mod_misc.h> 80 #include <security/openpam.h> 81 82 #define COMPAT_HEIMDAL 83 /* #define COMPAT_MIT */ 84 85 static int verify_krb_v5_tgt(krb5_context, krb5_ccache, char *, int); 86 static void cleanup_cache(pam_handle_t *, void *, int); 87 static const char *compat_princ_component(krb5_context, krb5_principal, int); 88 static void compat_free_data_contents(krb5_context, krb5_data *); 89 90 #define USER_PROMPT "Username: " 91 #define PASSWORD_PROMPT "Password:" 92 #define NEW_PASSWORD_PROMPT "New Password:" 93 94 #define PAM_OPT_CCACHE "ccache" 95 #define PAM_OPT_DEBUG "debug" 96 #define PAM_OPT_FORWARDABLE "forwardable" 97 #define PAM_OPT_NO_CCACHE "no_ccache" 98 #define PAM_OPT_REUSE_CCACHE "reuse_ccache" 99 100 /* 101 * authentication management 102 */ 103 PAM_EXTERN int 104 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused, 105 int argc __unused, const char *argv[] __unused) 106 { 107 krb5_error_code krbret; 108 krb5_context pam_context; 109 krb5_creds creds; 110 krb5_principal princ; 111 krb5_ccache ccache; 112 krb5_get_init_creds_opt opts; 113 struct passwd *pwd; 114 int retval; 115 void *ccache_data; 116 const char *user, *pass; 117 const void *sourceuser, *service; 118 char *principal, *princ_name, *ccache_name, luser[32], *srvdup; 119 120 retval = pam_get_user(pamh, &user, USER_PROMPT); 121 if (retval != PAM_SUCCESS) 122 return (retval); 123 124 PAM_LOG("Got user: %s", user); 125 126 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 127 if (retval != PAM_SUCCESS) 128 return (retval); 129 130 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 131 132 service = NULL; 133 pam_get_item(pamh, PAM_SERVICE, &service); 134 if (service == NULL) 135 service = "unknown"; 136 137 PAM_LOG("Got service: %s", (const char *)service); 138 139 krbret = krb5_init_context(&pam_context); 140 if (krbret != 0) { 141 PAM_VERBOSE_ERROR("Kerberos 5 error"); 142 return (PAM_SERVICE_ERR); 143 } 144 145 PAM_LOG("Context initialised"); 146 147 krb5_get_init_creds_opt_init(&opts); 148 149 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 150 krb5_get_init_creds_opt_set_forwardable(&opts, 1); 151 152 PAM_LOG("Credentials initialised"); 153 154 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 155 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 156 PAM_VERBOSE_ERROR("Kerberos 5 error"); 157 retval = PAM_SERVICE_ERR; 158 goto cleanup3; 159 } 160 161 PAM_LOG("Done krb5_cc_register()"); 162 163 /* Get principal name */ 164 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 165 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 166 else 167 principal = strdup(user); 168 169 PAM_LOG("Created principal: %s", principal); 170 171 krbret = krb5_parse_name(pam_context, principal, &princ); 172 free(principal); 173 if (krbret != 0) { 174 PAM_LOG("Error krb5_parse_name(): %s", 175 krb5_get_err_text(pam_context, krbret)); 176 PAM_VERBOSE_ERROR("Kerberos 5 error"); 177 retval = PAM_SERVICE_ERR; 178 goto cleanup3; 179 } 180 181 PAM_LOG("Done krb5_parse_name()"); 182 183 /* Now convert the principal name into something human readable */ 184 princ_name = NULL; 185 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 186 if (krbret != 0) { 187 PAM_LOG("Error krb5_unparse_name(): %s", 188 krb5_get_err_text(pam_context, krbret)); 189 PAM_VERBOSE_ERROR("Kerberos 5 error"); 190 retval = PAM_SERVICE_ERR; 191 goto cleanup2; 192 } 193 194 PAM_LOG("Got principal: %s", princ_name); 195 196 /* Get password */ 197 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT); 198 if (retval != PAM_SUCCESS) 199 goto cleanup2; 200 201 PAM_LOG("Got password"); 202 203 /* Verify the local user exists (AFTER getting the password) */ 204 if (strchr(user, '@')) { 205 /* get a local account name for this principal */ 206 krbret = krb5_aname_to_localname(pam_context, princ, 207 sizeof(luser), luser); 208 if (krbret != 0) { 209 PAM_VERBOSE_ERROR("Kerberos 5 error"); 210 PAM_LOG("Error krb5_aname_to_localname(): %s", 211 krb5_get_err_text(pam_context, krbret)); 212 retval = PAM_USER_UNKNOWN; 213 goto cleanup2; 214 } 215 216 retval = pam_set_item(pamh, PAM_USER, luser); 217 if (retval != PAM_SUCCESS) 218 goto cleanup2; 219 220 PAM_LOG("PAM_USER Redone"); 221 } 222 223 pwd = getpwnam(user); 224 if (pwd == NULL) { 225 retval = PAM_USER_UNKNOWN; 226 goto cleanup2; 227 } 228 229 PAM_LOG("Done getpwnam()"); 230 231 /* Get a TGT */ 232 memset(&creds, 0, sizeof(krb5_creds)); 233 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 234 pass, NULL, pamh, 0, NULL, &opts); 235 if (krbret != 0) { 236 PAM_VERBOSE_ERROR("Kerberos 5 error"); 237 PAM_LOG("Error krb5_get_init_creds_password(): %s", 238 krb5_get_err_text(pam_context, krbret)); 239 retval = PAM_AUTH_ERR; 240 goto cleanup2; 241 } 242 243 PAM_LOG("Got TGT"); 244 245 /* Generate a temporary cache */ 246 krbret = krb5_cc_gen_new(pam_context, &krb5_mcc_ops, &ccache); 247 if (krbret != 0) { 248 PAM_VERBOSE_ERROR("Kerberos 5 error"); 249 PAM_LOG("Error krb5_cc_gen_new(): %s", 250 krb5_get_err_text(pam_context, krbret)); 251 retval = PAM_SERVICE_ERR; 252 goto cleanup; 253 } 254 krbret = krb5_cc_initialize(pam_context, ccache, princ); 255 if (krbret != 0) { 256 PAM_VERBOSE_ERROR("Kerberos 5 error"); 257 PAM_LOG("Error krb5_cc_initialize(): %s", 258 krb5_get_err_text(pam_context, krbret)); 259 retval = PAM_SERVICE_ERR; 260 goto cleanup; 261 } 262 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 263 if (krbret != 0) { 264 PAM_VERBOSE_ERROR("Kerberos 5 error"); 265 PAM_LOG("Error krb5_cc_store_cred(): %s", 266 krb5_get_err_text(pam_context, krbret)); 267 krb5_cc_destroy(pam_context, ccache); 268 retval = PAM_SERVICE_ERR; 269 goto cleanup; 270 } 271 272 PAM_LOG("Credentials stashed"); 273 274 /* Verify them */ 275 if ((srvdup = strdup(service)) == NULL) { 276 retval = PAM_BUF_ERR; 277 goto cleanup; 278 } 279 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 280 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 281 free(srvdup); 282 if (krbret == -1) { 283 PAM_VERBOSE_ERROR("Kerberos 5 error"); 284 krb5_cc_destroy(pam_context, ccache); 285 retval = PAM_AUTH_ERR; 286 goto cleanup; 287 } 288 289 PAM_LOG("Credentials stash verified"); 290 291 retval = pam_get_data(pamh, "ccache", &ccache_data); 292 if (retval == PAM_SUCCESS) { 293 krb5_cc_destroy(pam_context, ccache); 294 PAM_VERBOSE_ERROR("Kerberos 5 error"); 295 retval = PAM_AUTH_ERR; 296 goto cleanup; 297 } 298 299 PAM_LOG("Credentials stash not pre-existing"); 300 301 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 302 ccache), krb5_cc_get_name(pam_context, ccache)); 303 if (ccache_name == NULL) { 304 PAM_VERBOSE_ERROR("Kerberos 5 error"); 305 retval = PAM_BUF_ERR; 306 goto cleanup; 307 } 308 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 309 if (retval != 0) { 310 krb5_cc_destroy(pam_context, ccache); 311 PAM_VERBOSE_ERROR("Kerberos 5 error"); 312 retval = PAM_SERVICE_ERR; 313 goto cleanup; 314 } 315 316 PAM_LOG("Credentials stash saved"); 317 318 cleanup: 319 krb5_free_cred_contents(pam_context, &creds); 320 PAM_LOG("Done cleanup"); 321 cleanup2: 322 krb5_free_principal(pam_context, princ); 323 PAM_LOG("Done cleanup2"); 324 cleanup3: 325 if (princ_name) 326 free(princ_name); 327 328 krb5_free_context(pam_context); 329 330 PAM_LOG("Done cleanup3"); 331 332 if (retval != PAM_SUCCESS) 333 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 334 335 return (retval); 336 } 337 338 PAM_EXTERN int 339 pam_sm_setcred(pam_handle_t *pamh, int flags, 340 int argc __unused, const char *argv[] __unused) 341 { 342 343 krb5_error_code krbret; 344 krb5_context pam_context; 345 krb5_principal princ; 346 krb5_creds creds; 347 krb5_ccache ccache_temp, ccache_perm; 348 krb5_cc_cursor cursor; 349 struct passwd *pwd = NULL; 350 int retval; 351 const char *cache_name, *q; 352 const void *user; 353 void *cache_data; 354 char *cache_name_buf = NULL, *p; 355 356 uid_t euid; 357 gid_t egid; 358 359 if (flags & PAM_DELETE_CRED) 360 return (PAM_SUCCESS); 361 362 if (flags & PAM_REFRESH_CRED) 363 return (PAM_SUCCESS); 364 365 if (flags & PAM_REINITIALIZE_CRED) 366 return (PAM_SUCCESS); 367 368 if (!(flags & PAM_ESTABLISH_CRED)) 369 return (PAM_SERVICE_ERR); 370 371 /* If a persistent cache isn't desired, stop now. */ 372 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE)) 373 return (PAM_SUCCESS); 374 375 PAM_LOG("Establishing credentials"); 376 377 /* Get username */ 378 retval = pam_get_item(pamh, PAM_USER, &user); 379 if (retval != PAM_SUCCESS) 380 return (retval); 381 382 PAM_LOG("Got user: %s", (const char *)user); 383 384 krbret = krb5_init_context(&pam_context); 385 if (krbret != 0) { 386 PAM_LOG("Error krb5_init_context() failed"); 387 return (PAM_SERVICE_ERR); 388 } 389 390 PAM_LOG("Context initialised"); 391 392 euid = geteuid(); /* Usually 0 */ 393 egid = getegid(); 394 395 PAM_LOG("Got euid, egid: %d %d", euid, egid); 396 397 /* Retrieve the temporary cache */ 398 retval = pam_get_data(pamh, "ccache", &cache_data); 399 if (retval != PAM_SUCCESS) { 400 retval = PAM_CRED_UNAVAIL; 401 goto cleanup3; 402 } 403 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 404 if (krbret != 0) { 405 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 406 krb5_get_err_text(pam_context, krbret)); 407 retval = PAM_SERVICE_ERR; 408 goto cleanup3; 409 } 410 411 /* Get the uid. This should exist. */ 412 pwd = getpwnam(user); 413 if (pwd == NULL) { 414 retval = PAM_USER_UNKNOWN; 415 goto cleanup3; 416 } 417 418 PAM_LOG("Done getpwnam()"); 419 420 /* Avoid following a symlink as root */ 421 if (setegid(pwd->pw_gid)) { 422 retval = PAM_SERVICE_ERR; 423 goto cleanup3; 424 } 425 if (seteuid(pwd->pw_uid)) { 426 retval = PAM_SERVICE_ERR; 427 goto cleanup3; 428 } 429 430 PAM_LOG("Done setegid() & seteuid()"); 431 432 /* Get the cache name */ 433 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 434 if (cache_name == NULL) { 435 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 436 cache_name = cache_name_buf; 437 } 438 439 p = calloc(PATH_MAX + 16, sizeof(char)); 440 q = cache_name; 441 442 if (p == NULL) { 443 PAM_LOG("Error malloc(): failure"); 444 retval = PAM_BUF_ERR; 445 goto cleanup3; 446 } 447 cache_name = p; 448 449 /* convert %u and %p */ 450 while (*q) { 451 if (*q == '%') { 452 q++; 453 if (*q == 'u') { 454 sprintf(p, "%d", pwd->pw_uid); 455 p += strlen(p); 456 } 457 else if (*q == 'p') { 458 sprintf(p, "%d", getpid()); 459 p += strlen(p); 460 } 461 else { 462 /* Not a special token */ 463 *p++ = '%'; 464 q--; 465 } 466 q++; 467 } 468 else { 469 *p++ = *q++; 470 } 471 } 472 473 PAM_LOG("Got cache_name: %s", cache_name); 474 475 /* Initialize the new ccache */ 476 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 477 if (krbret != 0) { 478 PAM_LOG("Error krb5_cc_get_principal(): %s", 479 krb5_get_err_text(pam_context, krbret)); 480 retval = PAM_SERVICE_ERR; 481 goto cleanup3; 482 } 483 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 484 if (krbret != 0) { 485 PAM_LOG("Error krb5_cc_resolve(): %s", 486 krb5_get_err_text(pam_context, krbret)); 487 retval = PAM_SERVICE_ERR; 488 goto cleanup2; 489 } 490 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 491 if (krbret != 0) { 492 PAM_LOG("Error krb5_cc_initialize(): %s", 493 krb5_get_err_text(pam_context, krbret)); 494 retval = PAM_SERVICE_ERR; 495 goto cleanup2; 496 } 497 498 PAM_LOG("Cache initialised"); 499 500 /* Prepare for iteration over creds */ 501 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 502 if (krbret != 0) { 503 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 504 krb5_get_err_text(pam_context, krbret)); 505 krb5_cc_destroy(pam_context, ccache_perm); 506 retval = PAM_SERVICE_ERR; 507 goto cleanup2; 508 } 509 510 PAM_LOG("Prepared for iteration"); 511 512 /* Copy the creds (should be two of them) */ 513 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 514 &cursor, &creds) == 0)) { 515 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 516 if (krbret != 0) { 517 PAM_LOG("Error krb5_cc_store_cred(): %s", 518 krb5_get_err_text(pam_context, krbret)); 519 krb5_cc_destroy(pam_context, ccache_perm); 520 krb5_free_cred_contents(pam_context, &creds); 521 retval = PAM_SERVICE_ERR; 522 goto cleanup2; 523 } 524 krb5_free_cred_contents(pam_context, &creds); 525 PAM_LOG("Iteration"); 526 } 527 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 528 529 PAM_LOG("Done iterating"); 530 531 if (strstr(cache_name, "FILE:") == cache_name) { 532 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 533 PAM_LOG("Error chown(): %s", strerror(errno)); 534 krb5_cc_destroy(pam_context, ccache_perm); 535 retval = PAM_SERVICE_ERR; 536 goto cleanup2; 537 } 538 PAM_LOG("Done chown()"); 539 540 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 541 PAM_LOG("Error chmod(): %s", strerror(errno)); 542 krb5_cc_destroy(pam_context, ccache_perm); 543 retval = PAM_SERVICE_ERR; 544 goto cleanup2; 545 } 546 PAM_LOG("Done chmod()"); 547 } 548 549 krb5_cc_close(pam_context, ccache_perm); 550 551 PAM_LOG("Cache closed"); 552 553 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 554 if (retval != PAM_SUCCESS) { 555 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 556 krb5_cc_destroy(pam_context, ccache_perm); 557 retval = PAM_SERVICE_ERR; 558 goto cleanup2; 559 } 560 561 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 562 563 cleanup2: 564 krb5_free_principal(pam_context, princ); 565 PAM_LOG("Done cleanup2"); 566 cleanup3: 567 krb5_free_context(pam_context); 568 PAM_LOG("Done cleanup3"); 569 570 seteuid(euid); 571 setegid(egid); 572 573 PAM_LOG("Done seteuid() & setegid()"); 574 575 if (cache_name_buf != NULL) 576 free(cache_name_buf); 577 578 return (retval); 579 } 580 581 /* 582 * account management 583 */ 584 PAM_EXTERN int 585 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 586 int argc __unused, const char *argv[] __unused) 587 { 588 krb5_error_code krbret; 589 krb5_context pam_context; 590 krb5_ccache ccache; 591 krb5_principal princ; 592 int retval; 593 const void *user; 594 void *ccache_name; 595 596 retval = pam_get_item(pamh, PAM_USER, &user); 597 if (retval != PAM_SUCCESS) 598 return (retval); 599 600 PAM_LOG("Got user: %s", (const char *)user); 601 602 retval = pam_get_data(pamh, "ccache", &ccache_name); 603 if (retval != PAM_SUCCESS) 604 return (PAM_SUCCESS); 605 606 PAM_LOG("Got credentials"); 607 608 krbret = krb5_init_context(&pam_context); 609 if (krbret != 0) { 610 PAM_LOG("Error krb5_init_context() failed"); 611 return (PAM_PERM_DENIED); 612 } 613 614 PAM_LOG("Context initialised"); 615 616 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 617 if (krbret != 0) { 618 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 619 krb5_get_err_text(pam_context, krbret)); 620 krb5_free_context(pam_context); 621 return (PAM_PERM_DENIED); 622 } 623 624 PAM_LOG("Got ccache %s", (const char *)ccache_name); 625 626 627 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 628 if (krbret != 0) { 629 PAM_LOG("Error krb5_cc_get_principal(): %s", 630 krb5_get_err_text(pam_context, krbret)); 631 retval = PAM_PERM_DENIED;; 632 goto cleanup; 633 } 634 635 PAM_LOG("Got principal"); 636 637 if (krb5_kuserok(pam_context, princ, (const char *)user)) 638 retval = PAM_SUCCESS; 639 else 640 retval = PAM_PERM_DENIED; 641 krb5_free_principal(pam_context, princ); 642 643 PAM_LOG("Done kuserok()"); 644 645 cleanup: 646 krb5_free_context(pam_context); 647 PAM_LOG("Done cleanup"); 648 649 return (retval); 650 651 } 652 653 /* 654 * password management 655 */ 656 PAM_EXTERN int 657 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 658 int argc __unused, const char *argv[] __unused) 659 { 660 krb5_error_code krbret; 661 krb5_context pam_context; 662 krb5_creds creds; 663 krb5_principal princ; 664 krb5_get_init_creds_opt opts; 665 krb5_data result_code_string, result_string; 666 int result_code, retval; 667 const char *pass; 668 const void *user; 669 char *princ_name, *passdup; 670 671 if (flags & PAM_PRELIM_CHECK) { 672 /* Nothing to do here. */ 673 return (PAM_SUCCESS); 674 } 675 676 if (!(flags & PAM_UPDATE_AUTHTOK)) { 677 PAM_LOG("Illegal flags argument"); 678 return (PAM_ABORT); 679 } 680 681 retval = pam_get_item(pamh, PAM_USER, &user); 682 if (retval != PAM_SUCCESS) 683 return (retval); 684 685 PAM_LOG("Got user: %s", (const char *)user); 686 687 krbret = krb5_init_context(&pam_context); 688 if (krbret != 0) { 689 PAM_LOG("Error krb5_init_context() failed"); 690 return (PAM_SERVICE_ERR); 691 } 692 693 PAM_LOG("Context initialised"); 694 695 krb5_get_init_creds_opt_init(&opts); 696 697 PAM_LOG("Credentials options initialised"); 698 699 /* Get principal name */ 700 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 701 if (krbret != 0) { 702 PAM_LOG("Error krb5_parse_name(): %s", 703 krb5_get_err_text(pam_context, krbret)); 704 retval = PAM_USER_UNKNOWN; 705 goto cleanup3; 706 } 707 708 /* Now convert the principal name into something human readable */ 709 princ_name = NULL; 710 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 711 if (krbret != 0) { 712 PAM_LOG("Error krb5_unparse_name(): %s", 713 krb5_get_err_text(pam_context, krbret)); 714 retval = PAM_SERVICE_ERR; 715 goto cleanup2; 716 } 717 718 PAM_LOG("Got principal: %s", princ_name); 719 720 /* Get password */ 721 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT); 722 if (retval != PAM_SUCCESS) 723 goto cleanup2; 724 725 PAM_LOG("Got password"); 726 727 memset(&creds, 0, sizeof(krb5_creds)); 728 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 729 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 730 if (krbret != 0) { 731 PAM_LOG("Error krb5_get_init_creds_password(): %s", 732 krb5_get_err_text(pam_context, krbret)); 733 retval = PAM_AUTH_ERR; 734 goto cleanup2; 735 } 736 737 PAM_LOG("Credentials established"); 738 739 /* Now get the new password */ 740 for (;;) { 741 retval = pam_get_authtok(pamh, 742 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 743 if (retval != PAM_TRY_AGAIN) 744 break; 745 pam_error(pamh, "Mismatch; try again, EOF to quit."); 746 } 747 if (retval != PAM_SUCCESS) 748 goto cleanup; 749 750 PAM_LOG("Got new password"); 751 752 /* Change it */ 753 if ((passdup = strdup(pass)) == NULL) { 754 retval = PAM_BUF_ERR; 755 goto cleanup; 756 } 757 krbret = krb5_change_password(pam_context, &creds, passdup, 758 &result_code, &result_code_string, &result_string); 759 free(passdup); 760 if (krbret != 0) { 761 PAM_LOG("Error krb5_change_password(): %s", 762 krb5_get_err_text(pam_context, krbret)); 763 retval = PAM_AUTHTOK_ERR; 764 goto cleanup; 765 } 766 if (result_code) { 767 PAM_LOG("Error krb5_change_password(): (result_code)"); 768 retval = PAM_AUTHTOK_ERR; 769 goto cleanup; 770 } 771 772 PAM_LOG("Password changed"); 773 774 if (result_string.data) 775 free(result_string.data); 776 if (result_code_string.data) 777 free(result_code_string.data); 778 779 cleanup: 780 krb5_free_cred_contents(pam_context, &creds); 781 PAM_LOG("Done cleanup"); 782 cleanup2: 783 krb5_free_principal(pam_context, princ); 784 PAM_LOG("Done cleanup2"); 785 cleanup3: 786 if (princ_name) 787 free(princ_name); 788 789 krb5_free_context(pam_context); 790 791 PAM_LOG("Done cleanup3"); 792 793 return (retval); 794 } 795 796 PAM_MODULE_ENTRY("pam_krb5"); 797 798 /* 799 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 800 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 801 * for Debian. 802 * 803 * Verify the Kerberos ticket-granting ticket just retrieved for the 804 * user. If the Kerberos server doesn't respond, assume the user is 805 * trying to fake us out (since we DID just get a TGT from what is 806 * supposedly our KDC). If the host/<host> service is unknown (i.e., 807 * the local keytab doesn't have it), and we cannot find another 808 * service we do have, let her in. 809 * 810 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 811 */ 812 /* ARGSUSED */ 813 static int 814 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 815 char *pam_service, int debug) 816 { 817 krb5_error_code retval; 818 krb5_principal princ; 819 krb5_keyblock *keyblock; 820 krb5_data packet; 821 krb5_auth_context auth_context; 822 char phost[BUFSIZ]; 823 const char *services[3], **service; 824 825 packet.data = 0; 826 827 /* If possible we want to try and verify the ticket we have 828 * received against a keytab. We will try multiple service 829 * principals, including at least the host principal and the PAM 830 * service principal. The host principal is preferred because access 831 * to that key is generally sufficient to compromise root, while the 832 * service key for this PAM service may be less carefully guarded. 833 * It is important to check the keytab first before the KDC so we do 834 * not get spoofed by a fake KDC. 835 */ 836 services[0] = "host"; 837 services[1] = pam_service; 838 services[2] = NULL; 839 keyblock = 0; 840 retval = -1; 841 for (service = &services[0]; *service != NULL; service++) { 842 retval = krb5_sname_to_principal(context, NULL, *service, 843 KRB5_NT_SRV_HST, &princ); 844 if (retval != 0) { 845 if (debug) 846 syslog(LOG_DEBUG, 847 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 848 "krb5_sname_to_principal()", 849 krb5_get_err_text(context, retval)); 850 return -1; 851 } 852 853 /* Extract the name directly. */ 854 strncpy(phost, compat_princ_component(context, princ, 1), 855 BUFSIZ); 856 phost[BUFSIZ - 1] = '\0'; 857 858 /* 859 * Do we have service/<host> keys? 860 * (use default/configured keytab, kvno IGNORE_VNO to get the 861 * first match, and ignore enctype.) 862 */ 863 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 864 &keyblock); 865 if (retval != 0) 866 continue; 867 break; 868 } 869 if (retval != 0) { /* failed to find key */ 870 /* Keytab or service key does not exist */ 871 if (debug) 872 syslog(LOG_DEBUG, 873 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 874 "krb5_kt_read_service_key()", 875 krb5_get_err_text(context, retval)); 876 retval = 0; 877 goto cleanup; 878 } 879 if (keyblock) 880 krb5_free_keyblock(context, keyblock); 881 882 /* Talk to the kdc and construct the ticket. */ 883 auth_context = NULL; 884 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 885 NULL, ccache, &packet); 886 if (auth_context) { 887 krb5_auth_con_free(context, auth_context); 888 auth_context = NULL; /* setup for rd_req */ 889 } 890 if (retval) { 891 if (debug) 892 syslog(LOG_DEBUG, 893 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 894 "krb5_mk_req()", 895 krb5_get_err_text(context, retval)); 896 retval = -1; 897 goto cleanup; 898 } 899 900 /* Try to use the ticket. */ 901 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 902 NULL, NULL); 903 if (retval) { 904 if (debug) 905 syslog(LOG_DEBUG, 906 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 907 "krb5_rd_req()", 908 krb5_get_err_text(context, retval)); 909 retval = -1; 910 } 911 else 912 retval = 1; 913 914 cleanup: 915 if (packet.data) 916 compat_free_data_contents(context, &packet); 917 krb5_free_principal(context, princ); 918 return retval; 919 } 920 921 /* Free the memory for cache_name. Called by pam_end() */ 922 /* ARGSUSED */ 923 static void 924 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 925 { 926 krb5_context pam_context; 927 krb5_ccache ccache; 928 krb5_error_code krbret; 929 930 if (krb5_init_context(&pam_context)) 931 return; 932 933 krbret = krb5_cc_resolve(pam_context, data, &ccache); 934 if (krbret == 0) 935 krb5_cc_destroy(pam_context, ccache); 936 krb5_free_context(pam_context); 937 free(data); 938 } 939 940 #ifdef COMPAT_HEIMDAL 941 #ifdef COMPAT_MIT 942 #error This cannot be MIT and Heimdal compatible! 943 #endif 944 #endif 945 946 #ifndef COMPAT_HEIMDAL 947 #ifndef COMPAT_MIT 948 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 949 #endif 950 #endif 951 952 #ifdef COMPAT_HEIMDAL 953 /* ARGSUSED */ 954 static const char * 955 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 956 { 957 return princ->name.name_string.val[n]; 958 } 959 960 /* ARGSUSED */ 961 static void 962 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 963 { 964 krb5_xfree(data->data); 965 } 966 #endif 967 968 #ifdef COMPAT_MIT 969 static const char * 970 compat_princ_component(krb5_context context, krb5_principal princ, int n) 971 { 972 return krb5_princ_component(context, princ, n)->data; 973 } 974 975 static void 976 compat_free_data_contents(krb5_context context, krb5_data * data) 977 { 978 krb5_free_data_contents(context, data); 979 } 980 #endif 981
Indexes created Mon Sep 29 21:09:56 GMT 2025