pam_krb5.c revision 1.1
1 /*- 2 * This pam_krb5 module contains code that is: 3 * Copyright (c) Derrick J. Brashear, 1996. All rights reserved. 4 * Copyright (c) Frank Cusack, 1999-2001. All rights reserved. 5 * Copyright (c) Jacques A. Vidrine, 2000-2001. All rights reserved. 6 * Copyright (c) Nicolas Williams, 2001. All rights reserved. 7 * Copyright (c) Perot Systems Corporation, 2001. All rights reserved. 8 * Copyright (c) Mark R V Murray, 2001. All rights reserved. 9 * Copyright (c) Networks Associates Technology, Inc., 2002-2003. 10 * All rights reserved. 11 * 12 * Portions of this software were developed for the FreeBSD Project by 13 * ThinkSec AS and NAI Labs, the Security Research Division of Network 14 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 15 * ("CBOSS"), as part of the DARPA CHATS research program. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notices, and the entire permission notice in its entirety, 22 * including the disclaimer of warranties. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 3. The name of the author may not be used to endorse or promote 27 * products derived from this software without specific prior 28 * written permission. 29 * 30 * ALTERNATIVELY, this product may be distributed under the terms of 31 * the GNU Public License, in which case the provisions of the GPL are 32 * required INSTEAD OF the above restrictions. (This clause is 33 * necessary due to a potential bad interaction between the GPL and 34 * the restrictions contained in a BSD-style copyright.) 35 * 36 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED 37 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 38 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 39 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, 40 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 41 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 42 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 44 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 45 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 46 * OF THE POSSIBILITY OF SUCH DAMAGE. 47 * 48 */ 49 50 #include <sys/cdefs.h> 51 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_krb5/pam_krb5.c,v 1.20 2004/02/10 10:13:20 des Exp $"); 52 53 #include <sys/types.h> 54 #include <sys/stat.h> 55 #include <errno.h> 56 #include <limits.h> 57 #include <pwd.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <syslog.h> 62 #include <unistd.h> 63 64 #include <krb5.h> 65 #include <com_err.h> 66 67 #define PAM_SM_AUTH 68 #define PAM_SM_ACCOUNT 69 #define PAM_SM_PASSWORD 70 71 #include <security/pam_appl.h> 72 #include <security/pam_modules.h> 73 #include <security/pam_mod_misc.h> 74 #include <security/openpam.h> 75 76 #define COMPAT_HEIMDAL 77 /* #define COMPAT_MIT */ 78 79 static int verify_krb_v5_tgt(krb5_context, krb5_ccache, char *, int); 80 static void cleanup_cache(pam_handle_t *, void *, int); 81 static const char *compat_princ_component(krb5_context, krb5_principal, int); 82 static void compat_free_data_contents(krb5_context, krb5_data *); 83 84 #define USER_PROMPT "Username: " 85 #define PASSWORD_PROMPT "Password:" 86 #define NEW_PASSWORD_PROMPT "New Password:" 87 88 #define PAM_OPT_CCACHE "ccache" 89 #define PAM_OPT_FORWARDABLE "forwardable" 90 #define PAM_OPT_NO_CCACHE "no_ccache" 91 #define PAM_OPT_REUSE_CCACHE "reuse_ccache" 92 93 /* 94 * authentication management 95 */ 96 PAM_EXTERN int 97 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused, 98 int argc __unused, const char *argv[] __unused) 99 { 100 krb5_error_code krbret; 101 krb5_context pam_context; 102 krb5_creds creds; 103 krb5_principal princ; 104 krb5_ccache ccache; 105 krb5_get_init_creds_opt opts; 106 struct passwd *pwd; 107 int retval; 108 void *ccache_data; 109 const char *user, *pass; 110 const void *sourceuser, *service; 111 char *principal, *princ_name, *ccache_name, luser[32], *srvdup; 112 113 retval = pam_get_user(pamh, &user, USER_PROMPT); 114 if (retval != PAM_SUCCESS) 115 return (retval); 116 117 PAM_LOG("Got user: %s", user); 118 119 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 120 if (retval != PAM_SUCCESS) 121 return (retval); 122 123 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 124 125 service = NULL; 126 pam_get_item(pamh, PAM_SERVICE, &service); 127 if (service == NULL) 128 service = "unknown"; 129 130 PAM_LOG("Got service: %s", (const char *)service); 131 132 krbret = krb5_init_context(&pam_context); 133 if (krbret != 0) { 134 PAM_VERBOSE_ERROR("Kerberos 5 error"); 135 return (PAM_SERVICE_ERR); 136 } 137 138 PAM_LOG("Context initialised"); 139 140 krb5_get_init_creds_opt_init(&opts); 141 142 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 143 krb5_get_init_creds_opt_set_forwardable(&opts, 1); 144 145 PAM_LOG("Credentials initialised"); 146 147 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 148 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 149 PAM_VERBOSE_ERROR("Kerberos 5 error"); 150 retval = PAM_SERVICE_ERR; 151 goto cleanup3; 152 } 153 154 PAM_LOG("Done krb5_cc_register()"); 155 156 /* Get principal name */ 157 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 158 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 159 else 160 principal = strdup(user); 161 162 PAM_LOG("Created principal: %s", principal); 163 164 krbret = krb5_parse_name(pam_context, principal, &princ); 165 free(principal); 166 if (krbret != 0) { 167 PAM_LOG("Error krb5_parse_name(): %s", 168 krb5_get_err_text(pam_context, krbret)); 169 PAM_VERBOSE_ERROR("Kerberos 5 error"); 170 retval = PAM_SERVICE_ERR; 171 goto cleanup3; 172 } 173 174 PAM_LOG("Done krb5_parse_name()"); 175 176 /* Now convert the principal name into something human readable */ 177 princ_name = NULL; 178 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 179 if (krbret != 0) { 180 PAM_LOG("Error krb5_unparse_name(): %s", 181 krb5_get_err_text(pam_context, krbret)); 182 PAM_VERBOSE_ERROR("Kerberos 5 error"); 183 retval = PAM_SERVICE_ERR; 184 goto cleanup2; 185 } 186 187 PAM_LOG("Got principal: %s", princ_name); 188 189 /* Get password */ 190 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT); 191 if (retval != PAM_SUCCESS) 192 goto cleanup2; 193 194 PAM_LOG("Got password"); 195 196 /* Verify the local user exists (AFTER getting the password) */ 197 if (strchr(user, '@')) { 198 /* get a local account name for this principal */ 199 krbret = krb5_aname_to_localname(pam_context, princ, 200 sizeof(luser), luser); 201 if (krbret != 0) { 202 PAM_VERBOSE_ERROR("Kerberos 5 error"); 203 PAM_LOG("Error krb5_aname_to_localname(): %s", 204 krb5_get_err_text(pam_context, krbret)); 205 retval = PAM_USER_UNKNOWN; 206 goto cleanup2; 207 } 208 209 retval = pam_set_item(pamh, PAM_USER, luser); 210 if (retval != PAM_SUCCESS) 211 goto cleanup2; 212 213 PAM_LOG("PAM_USER Redone"); 214 } 215 216 pwd = getpwnam(user); 217 if (pwd == NULL) { 218 retval = PAM_USER_UNKNOWN; 219 goto cleanup2; 220 } 221 222 PAM_LOG("Done getpwnam()"); 223 224 /* Get a TGT */ 225 memset(&creds, 0, sizeof(krb5_creds)); 226 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 227 pass, NULL, pamh, 0, NULL, &opts); 228 if (krbret != 0) { 229 PAM_VERBOSE_ERROR("Kerberos 5 error"); 230 PAM_LOG("Error krb5_get_init_creds_password(): %s", 231 krb5_get_err_text(pam_context, krbret)); 232 retval = PAM_AUTH_ERR; 233 goto cleanup2; 234 } 235 236 PAM_LOG("Got TGT"); 237 238 /* Generate a temporary cache */ 239 krbret = krb5_cc_gen_new(pam_context, &krb5_mcc_ops, &ccache); 240 if (krbret != 0) { 241 PAM_VERBOSE_ERROR("Kerberos 5 error"); 242 PAM_LOG("Error krb5_cc_gen_new(): %s", 243 krb5_get_err_text(pam_context, krbret)); 244 retval = PAM_SERVICE_ERR; 245 goto cleanup; 246 } 247 krbret = krb5_cc_initialize(pam_context, ccache, princ); 248 if (krbret != 0) { 249 PAM_VERBOSE_ERROR("Kerberos 5 error"); 250 PAM_LOG("Error krb5_cc_initialize(): %s", 251 krb5_get_err_text(pam_context, krbret)); 252 retval = PAM_SERVICE_ERR; 253 goto cleanup; 254 } 255 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 256 if (krbret != 0) { 257 PAM_VERBOSE_ERROR("Kerberos 5 error"); 258 PAM_LOG("Error krb5_cc_store_cred(): %s", 259 krb5_get_err_text(pam_context, krbret)); 260 krb5_cc_destroy(pam_context, ccache); 261 retval = PAM_SERVICE_ERR; 262 goto cleanup; 263 } 264 265 PAM_LOG("Credentials stashed"); 266 267 /* Verify them */ 268 if ((srvdup = strdup(service)) == NULL) { 269 retval = PAM_BUF_ERR; 270 goto cleanup; 271 } 272 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 273 openpam_get_option(pamh, PAM_OPT_FORWARDABLE) ? 1 : 0); 274 free(srvdup); 275 if (krbret == -1) { 276 PAM_VERBOSE_ERROR("Kerberos 5 error"); 277 krb5_cc_destroy(pam_context, ccache); 278 retval = PAM_AUTH_ERR; 279 goto cleanup; 280 } 281 282 PAM_LOG("Credentials stash verified"); 283 284 retval = pam_get_data(pamh, "ccache", &ccache_data); 285 if (retval == PAM_SUCCESS) { 286 krb5_cc_destroy(pam_context, ccache); 287 PAM_VERBOSE_ERROR("Kerberos 5 error"); 288 retval = PAM_AUTH_ERR; 289 goto cleanup; 290 } 291 292 PAM_LOG("Credentials stash not pre-existing"); 293 294 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 295 ccache), krb5_cc_get_name(pam_context, ccache)); 296 if (ccache_name == NULL) { 297 PAM_VERBOSE_ERROR("Kerberos 5 error"); 298 retval = PAM_BUF_ERR; 299 goto cleanup; 300 } 301 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 302 if (retval != 0) { 303 krb5_cc_destroy(pam_context, ccache); 304 PAM_VERBOSE_ERROR("Kerberos 5 error"); 305 retval = PAM_SERVICE_ERR; 306 goto cleanup; 307 } 308 309 PAM_LOG("Credentials stash saved"); 310 311 cleanup: 312 krb5_free_cred_contents(pam_context, &creds); 313 PAM_LOG("Done cleanup"); 314 cleanup2: 315 krb5_free_principal(pam_context, princ); 316 PAM_LOG("Done cleanup2"); 317 cleanup3: 318 if (princ_name) 319 free(princ_name); 320 321 krb5_free_context(pam_context); 322 323 PAM_LOG("Done cleanup3"); 324 325 if (retval != PAM_SUCCESS) 326 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 327 328 return (retval); 329 } 330 331 PAM_EXTERN int 332 pam_sm_setcred(pam_handle_t *pamh, int flags, 333 int argc __unused, const char *argv[] __unused) 334 { 335 336 krb5_error_code krbret; 337 krb5_context pam_context; 338 krb5_principal princ; 339 krb5_creds creds; 340 krb5_ccache ccache_temp, ccache_perm; 341 krb5_cc_cursor cursor; 342 struct passwd *pwd = NULL; 343 int retval; 344 const char *cache_name, *q; 345 const void *user; 346 void *cache_data; 347 char *cache_name_buf = NULL, *p; 348 349 uid_t euid; 350 gid_t egid; 351 352 if (flags & PAM_DELETE_CRED) 353 return (PAM_SUCCESS); 354 355 if (flags & PAM_REFRESH_CRED) 356 return (PAM_SUCCESS); 357 358 if (flags & PAM_REINITIALIZE_CRED) 359 return (PAM_SUCCESS); 360 361 if (!(flags & PAM_ESTABLISH_CRED)) 362 return (PAM_SERVICE_ERR); 363 364 PAM_LOG("Establishing credentials"); 365 366 /* Get username */ 367 retval = pam_get_item(pamh, PAM_USER, &user); 368 if (retval != PAM_SUCCESS) 369 return (retval); 370 371 PAM_LOG("Got user: %s", (const char *)user); 372 373 krbret = krb5_init_context(&pam_context); 374 if (krbret != 0) { 375 PAM_LOG("Error krb5_init_context() failed"); 376 return (PAM_SERVICE_ERR); 377 } 378 379 PAM_LOG("Context initialised"); 380 381 euid = geteuid(); /* Usually 0 */ 382 egid = getegid(); 383 384 PAM_LOG("Got euid, egid: %d %d", euid, egid); 385 386 /* Retrieve the temporary cache */ 387 retval = pam_get_data(pamh, "ccache", &cache_data); 388 if (retval != PAM_SUCCESS) { 389 retval = PAM_CRED_UNAVAIL; 390 goto cleanup3; 391 } 392 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 393 if (krbret != 0) { 394 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 395 krb5_get_err_text(pam_context, krbret)); 396 retval = PAM_SERVICE_ERR; 397 goto cleanup3; 398 } 399 400 /* Get the uid. This should exist. */ 401 pwd = getpwnam(user); 402 if (pwd == NULL) { 403 retval = PAM_USER_UNKNOWN; 404 goto cleanup3; 405 } 406 407 PAM_LOG("Done getpwnam()"); 408 409 /* Avoid following a symlink as root */ 410 if (setegid(pwd->pw_gid)) { 411 retval = PAM_SERVICE_ERR; 412 goto cleanup3; 413 } 414 if (seteuid(pwd->pw_uid)) { 415 retval = PAM_SERVICE_ERR; 416 goto cleanup3; 417 } 418 419 PAM_LOG("Done setegid() & seteuid()"); 420 421 /* Get the cache name */ 422 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 423 if (cache_name == NULL) { 424 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 425 cache_name = cache_name_buf; 426 } 427 428 p = calloc(PATH_MAX + 16, sizeof(char)); 429 q = cache_name; 430 431 if (p == NULL) { 432 PAM_LOG("Error malloc(): failure"); 433 retval = PAM_BUF_ERR; 434 goto cleanup3; 435 } 436 cache_name = p; 437 438 /* convert %u and %p */ 439 while (*q) { 440 if (*q == '%') { 441 q++; 442 if (*q == 'u') { 443 sprintf(p, "%d", pwd->pw_uid); 444 p += strlen(p); 445 } 446 else if (*q == 'p') { 447 sprintf(p, "%d", getpid()); 448 p += strlen(p); 449 } 450 else { 451 /* Not a special token */ 452 *p++ = '%'; 453 q--; 454 } 455 q++; 456 } 457 else { 458 *p++ = *q++; 459 } 460 } 461 462 PAM_LOG("Got cache_name: %s", cache_name); 463 464 /* Initialize the new ccache */ 465 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 466 if (krbret != 0) { 467 PAM_LOG("Error krb5_cc_get_principal(): %s", 468 krb5_get_err_text(pam_context, krbret)); 469 retval = PAM_SERVICE_ERR; 470 goto cleanup3; 471 } 472 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 473 if (krbret != 0) { 474 PAM_LOG("Error krb5_cc_resolve(): %s", 475 krb5_get_err_text(pam_context, krbret)); 476 retval = PAM_SERVICE_ERR; 477 goto cleanup2; 478 } 479 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 480 if (krbret != 0) { 481 PAM_LOG("Error krb5_cc_initialize(): %s", 482 krb5_get_err_text(pam_context, krbret)); 483 retval = PAM_SERVICE_ERR; 484 goto cleanup2; 485 } 486 487 PAM_LOG("Cache initialised"); 488 489 /* Prepare for iteration over creds */ 490 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 491 if (krbret != 0) { 492 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 493 krb5_get_err_text(pam_context, krbret)); 494 krb5_cc_destroy(pam_context, ccache_perm); 495 retval = PAM_SERVICE_ERR; 496 goto cleanup2; 497 } 498 499 PAM_LOG("Prepared for iteration"); 500 501 /* Copy the creds (should be two of them) */ 502 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 503 &cursor, &creds) == 0)) { 504 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 505 if (krbret != 0) { 506 PAM_LOG("Error krb5_cc_store_cred(): %s", 507 krb5_get_err_text(pam_context, krbret)); 508 krb5_cc_destroy(pam_context, ccache_perm); 509 krb5_free_cred_contents(pam_context, &creds); 510 retval = PAM_SERVICE_ERR; 511 goto cleanup2; 512 } 513 krb5_free_cred_contents(pam_context, &creds); 514 PAM_LOG("Iteration"); 515 } 516 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 517 518 PAM_LOG("Done iterating"); 519 520 if (strstr(cache_name, "FILE:") == cache_name) { 521 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 522 PAM_LOG("Error chown(): %s", strerror(errno)); 523 krb5_cc_destroy(pam_context, ccache_perm); 524 retval = PAM_SERVICE_ERR; 525 goto cleanup2; 526 } 527 PAM_LOG("Done chown()"); 528 529 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 530 PAM_LOG("Error chmod(): %s", strerror(errno)); 531 krb5_cc_destroy(pam_context, ccache_perm); 532 retval = PAM_SERVICE_ERR; 533 goto cleanup2; 534 } 535 PAM_LOG("Done chmod()"); 536 } 537 538 krb5_cc_close(pam_context, ccache_perm); 539 540 PAM_LOG("Cache closed"); 541 542 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 543 if (retval != PAM_SUCCESS) { 544 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 545 krb5_cc_destroy(pam_context, ccache_perm); 546 retval = PAM_SERVICE_ERR; 547 goto cleanup2; 548 } 549 550 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 551 552 cleanup2: 553 krb5_free_principal(pam_context, princ); 554 PAM_LOG("Done cleanup2"); 555 cleanup3: 556 krb5_free_context(pam_context); 557 PAM_LOG("Done cleanup3"); 558 559 seteuid(euid); 560 setegid(egid); 561 562 PAM_LOG("Done seteuid() & setegid()"); 563 564 if (cache_name_buf != NULL) 565 free(cache_name_buf); 566 567 return (retval); 568 } 569 570 /* 571 * account management 572 */ 573 PAM_EXTERN int 574 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 575 int argc __unused, const char *argv[] __unused) 576 { 577 krb5_error_code krbret; 578 krb5_context pam_context; 579 krb5_ccache ccache; 580 krb5_principal princ; 581 int retval; 582 const void *user; 583 void *ccache_name; 584 585 retval = pam_get_item(pamh, PAM_USER, &user); 586 if (retval != PAM_SUCCESS) 587 return (retval); 588 589 PAM_LOG("Got user: %s", (const char *)user); 590 591 retval = pam_get_data(pamh, "ccache", &ccache_name); 592 if (retval != PAM_SUCCESS) 593 return (PAM_SUCCESS); 594 595 PAM_LOG("Got credentials"); 596 597 krbret = krb5_init_context(&pam_context); 598 if (krbret != 0) { 599 PAM_LOG("Error krb5_init_context() failed"); 600 return (PAM_PERM_DENIED); 601 } 602 603 PAM_LOG("Context initialised"); 604 605 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 606 if (krbret != 0) { 607 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 608 krb5_get_err_text(pam_context, krbret)); 609 krb5_free_context(pam_context); 610 return (PAM_PERM_DENIED); 611 } 612 613 PAM_LOG("Got ccache %s", (const char *)ccache_name); 614 615 616 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 617 if (krbret != 0) { 618 PAM_LOG("Error krb5_cc_get_principal(): %s", 619 krb5_get_err_text(pam_context, krbret)); 620 retval = PAM_PERM_DENIED;; 621 goto cleanup; 622 } 623 624 PAM_LOG("Got principal"); 625 626 if (krb5_kuserok(pam_context, princ, (const char *)user)) 627 retval = PAM_SUCCESS; 628 else 629 retval = PAM_PERM_DENIED; 630 krb5_free_principal(pam_context, princ); 631 632 PAM_LOG("Done kuserok()"); 633 634 cleanup: 635 krb5_free_context(pam_context); 636 PAM_LOG("Done cleanup"); 637 638 return (retval); 639 640 } 641 642 /* 643 * password management 644 */ 645 PAM_EXTERN int 646 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 647 int argc __unused, const char *argv[] __unused) 648 { 649 krb5_error_code krbret; 650 krb5_context pam_context; 651 krb5_creds creds; 652 krb5_principal princ; 653 krb5_get_init_creds_opt opts; 654 krb5_data result_code_string, result_string; 655 int result_code, retval; 656 const char *pass; 657 const void *user; 658 char *princ_name, *passdup; 659 660 if (!(flags & PAM_UPDATE_AUTHTOK)) 661 return (PAM_AUTHTOK_ERR); 662 663 retval = pam_get_item(pamh, PAM_USER, &user); 664 if (retval != PAM_SUCCESS) 665 return (retval); 666 667 PAM_LOG("Got user: %s", (const char *)user); 668 669 krbret = krb5_init_context(&pam_context); 670 if (krbret != 0) { 671 PAM_LOG("Error krb5_init_context() failed"); 672 return (PAM_SERVICE_ERR); 673 } 674 675 PAM_LOG("Context initialised"); 676 677 krb5_get_init_creds_opt_init(&opts); 678 679 PAM_LOG("Credentials options initialised"); 680 681 /* Get principal name */ 682 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 683 if (krbret != 0) { 684 PAM_LOG("Error krb5_parse_name(): %s", 685 krb5_get_err_text(pam_context, krbret)); 686 retval = PAM_USER_UNKNOWN; 687 goto cleanup3; 688 } 689 690 /* Now convert the principal name into something human readable */ 691 princ_name = NULL; 692 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 693 if (krbret != 0) { 694 PAM_LOG("Error krb5_unparse_name(): %s", 695 krb5_get_err_text(pam_context, krbret)); 696 retval = PAM_SERVICE_ERR; 697 goto cleanup2; 698 } 699 700 PAM_LOG("Got principal: %s", princ_name); 701 702 /* Get password */ 703 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT); 704 if (retval != PAM_SUCCESS) 705 goto cleanup2; 706 707 PAM_LOG("Got password"); 708 709 memset(&creds, 0, sizeof(krb5_creds)); 710 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 711 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 712 if (krbret != 0) { 713 PAM_LOG("Error krb5_get_init_creds_password(): %s", 714 krb5_get_err_text(pam_context, krbret)); 715 retval = PAM_AUTH_ERR; 716 goto cleanup2; 717 } 718 719 PAM_LOG("Credentials established"); 720 721 /* Now get the new password */ 722 for (;;) { 723 retval = pam_get_authtok(pamh, 724 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 725 if (retval != PAM_TRY_AGAIN) 726 break; 727 pam_error(pamh, "Mismatch; try again, EOF to quit."); 728 } 729 if (retval != PAM_SUCCESS) 730 goto cleanup; 731 732 PAM_LOG("Got new password"); 733 734 /* Change it */ 735 if ((passdup = strdup(pass)) == NULL) { 736 retval = PAM_BUF_ERR; 737 goto cleanup; 738 } 739 krbret = krb5_change_password(pam_context, &creds, passdup, 740 &result_code, &result_code_string, &result_string); 741 free(passdup); 742 if (krbret != 0) { 743 PAM_LOG("Error krb5_change_password(): %s", 744 krb5_get_err_text(pam_context, krbret)); 745 retval = PAM_AUTHTOK_ERR; 746 goto cleanup; 747 } 748 if (result_code) { 749 PAM_LOG("Error krb5_change_password(): (result_code)"); 750 retval = PAM_AUTHTOK_ERR; 751 goto cleanup; 752 } 753 754 PAM_LOG("Password changed"); 755 756 if (result_string.data) 757 free(result_string.data); 758 if (result_code_string.data) 759 free(result_code_string.data); 760 761 cleanup: 762 krb5_free_cred_contents(pam_context, &creds); 763 PAM_LOG("Done cleanup"); 764 cleanup2: 765 krb5_free_principal(pam_context, princ); 766 PAM_LOG("Done cleanup2"); 767 cleanup3: 768 if (princ_name) 769 free(princ_name); 770 771 krb5_free_context(pam_context); 772 773 PAM_LOG("Done cleanup3"); 774 775 return (retval); 776 } 777 778 PAM_MODULE_ENTRY("pam_krb5"); 779 780 /* 781 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 782 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 783 * for Debian. 784 * 785 * Verify the Kerberos ticket-granting ticket just retrieved for the 786 * user. If the Kerberos server doesn't respond, assume the user is 787 * trying to fake us out (since we DID just get a TGT from what is 788 * supposedly our KDC). If the host/<host> service is unknown (i.e., 789 * the local keytab doesn't have it), and we cannot find another 790 * service we do have, let her in. 791 * 792 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 793 */ 794 /* ARGSUSED */ 795 static int 796 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 797 char *pam_service, int debug) 798 { 799 krb5_error_code retval; 800 krb5_principal princ; 801 krb5_keyblock *keyblock; 802 krb5_data packet; 803 krb5_auth_context auth_context; 804 char phost[BUFSIZ]; 805 const char *services[3], **service; 806 807 packet.data = 0; 808 809 /* If possible we want to try and verify the ticket we have 810 * received against a keytab. We will try multiple service 811 * principals, including at least the host principal and the PAM 812 * service principal. The host principal is preferred because access 813 * to that key is generally sufficient to compromise root, while the 814 * service key for this PAM service may be less carefully guarded. 815 * It is important to check the keytab first before the KDC so we do 816 * not get spoofed by a fake KDC. 817 */ 818 services[0] = "host"; 819 services[1] = pam_service; 820 services[2] = NULL; 821 keyblock = 0; 822 retval = -1; 823 for (service = &services[0]; *service != NULL; service++) { 824 retval = krb5_sname_to_principal(context, NULL, *service, 825 KRB5_NT_SRV_HST, &princ); 826 if (retval != 0) { 827 if (debug) 828 syslog(LOG_DEBUG, 829 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 830 "krb5_sname_to_principal()", 831 krb5_get_err_text(context, retval)); 832 return -1; 833 } 834 835 /* Extract the name directly. */ 836 strncpy(phost, compat_princ_component(context, princ, 1), 837 BUFSIZ); 838 phost[BUFSIZ - 1] = '\0'; 839 840 /* 841 * Do we have service/<host> keys? 842 * (use default/configured keytab, kvno IGNORE_VNO to get the 843 * first match, and ignore enctype.) 844 */ 845 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 846 &keyblock); 847 if (retval != 0) 848 continue; 849 break; 850 } 851 if (retval != 0) { /* failed to find key */ 852 /* Keytab or service key does not exist */ 853 if (debug) 854 syslog(LOG_DEBUG, 855 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 856 "krb5_kt_read_service_key()", 857 krb5_get_err_text(context, retval)); 858 retval = 0; 859 goto cleanup; 860 } 861 if (keyblock) 862 krb5_free_keyblock(context, keyblock); 863 864 /* Talk to the kdc and construct the ticket. */ 865 auth_context = NULL; 866 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 867 NULL, ccache, &packet); 868 if (auth_context) { 869 krb5_auth_con_free(context, auth_context); 870 auth_context = NULL; /* setup for rd_req */ 871 } 872 if (retval) { 873 if (debug) 874 syslog(LOG_DEBUG, 875 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 876 "krb5_mk_req()", 877 krb5_get_err_text(context, retval)); 878 retval = -1; 879 goto cleanup; 880 } 881 882 /* Try to use the ticket. */ 883 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 884 NULL, NULL); 885 if (retval) { 886 if (debug) 887 syslog(LOG_DEBUG, 888 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 889 "krb5_rd_req()", 890 krb5_get_err_text(context, retval)); 891 retval = -1; 892 } 893 else 894 retval = 1; 895 896 cleanup: 897 if (packet.data) 898 compat_free_data_contents(context, &packet); 899 krb5_free_principal(context, princ); 900 return retval; 901 } 902 903 /* Free the memory for cache_name. Called by pam_end() */ 904 /* ARGSUSED */ 905 static void 906 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 907 { 908 krb5_context pam_context; 909 krb5_ccache ccache; 910 krb5_error_code krbret; 911 912 if (krb5_init_context(&pam_context)) 913 return; 914 915 krbret = krb5_cc_resolve(pam_context, data, &ccache); 916 if (krbret == 0) 917 krb5_cc_destroy(pam_context, ccache); 918 krb5_free_context(pam_context); 919 free(data); 920 } 921 922 #ifdef COMPAT_HEIMDAL 923 #ifdef COMPAT_MIT 924 #error This cannot be MIT and Heimdal compatible! 925 #endif 926 #endif 927 928 #ifndef COMPAT_HEIMDAL 929 #ifndef COMPAT_MIT 930 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 931 #endif 932 #endif 933 934 #ifdef COMPAT_HEIMDAL 935 /* ARGSUSED */ 936 static const char * 937 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 938 { 939 return princ->name.name_string.val[n]; 940 } 941 942 /* ARGSUSED */ 943 static void 944 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 945 { 946 krb5_xfree(data->data); 947 } 948 #endif 949 950 #ifdef COMPAT_MIT 951 static const char * 952 compat_princ_component(krb5_context context, krb5_principal princ, int n) 953 { 954 return krb5_princ_component(context, princ, n)->data; 955 } 956 957 static void 958 compat_free_data_contents(krb5_context context, krb5_data * data) 959 { 960 krb5_free_data_contents(context, data); 961 } 962 #endif 963
Indexes created Mon Sep 29 21:09:56 GMT 2025