pam_krb5.c revision 1.2
1 /* $NetBSD: pam_krb5.c,v 1.2 2004/12/12 08:18:45 christos 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., 2002-2003. 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 1.20 2004/02/10 10:13:20 des Exp $"); 55 #else 56 __RCSID("$NetBSD: pam_krb5.c,v 1.2 2004/12/12 08:18:45 christos 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_FORWARDABLE "forwardable" 96 #define PAM_OPT_NO_CCACHE "no_ccache" 97 #define PAM_OPT_REUSE_CCACHE "reuse_ccache" 98 99 /* 100 * authentication management 101 */ 102 PAM_EXTERN int 103 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused, 104 int argc __unused, const char *argv[] __unused) 105 { 106 krb5_error_code krbret; 107 krb5_context pam_context; 108 krb5_creds creds; 109 krb5_principal princ; 110 krb5_ccache ccache; 111 krb5_get_init_creds_opt opts; 112 struct passwd *pwd; 113 int retval; 114 void *ccache_data; 115 const char *user, *pass; 116 const void *sourceuser, *service; 117 char *principal, *princ_name, *ccache_name, luser[32], *srvdup; 118 119 retval = pam_get_user(pamh, &user, USER_PROMPT); 120 if (retval != PAM_SUCCESS) 121 return (retval); 122 123 PAM_LOG("Got user: %s", user); 124 125 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 126 if (retval != PAM_SUCCESS) 127 return (retval); 128 129 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 130 131 service = NULL; 132 pam_get_item(pamh, PAM_SERVICE, &service); 133 if (service == NULL) 134 service = "unknown"; 135 136 PAM_LOG("Got service: %s", (const char *)service); 137 138 krbret = krb5_init_context(&pam_context); 139 if (krbret != 0) { 140 PAM_VERBOSE_ERROR("Kerberos 5 error"); 141 return (PAM_SERVICE_ERR); 142 } 143 144 PAM_LOG("Context initialised"); 145 146 krb5_get_init_creds_opt_init(&opts); 147 148 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 149 krb5_get_init_creds_opt_set_forwardable(&opts, 1); 150 151 PAM_LOG("Credentials initialised"); 152 153 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 154 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 155 PAM_VERBOSE_ERROR("Kerberos 5 error"); 156 retval = PAM_SERVICE_ERR; 157 goto cleanup3; 158 } 159 160 PAM_LOG("Done krb5_cc_register()"); 161 162 /* Get principal name */ 163 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 164 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 165 else 166 principal = strdup(user); 167 168 PAM_LOG("Created principal: %s", principal); 169 170 krbret = krb5_parse_name(pam_context, principal, &princ); 171 free(principal); 172 if (krbret != 0) { 173 PAM_LOG("Error krb5_parse_name(): %s", 174 krb5_get_err_text(pam_context, krbret)); 175 PAM_VERBOSE_ERROR("Kerberos 5 error"); 176 retval = PAM_SERVICE_ERR; 177 goto cleanup3; 178 } 179 180 PAM_LOG("Done krb5_parse_name()"); 181 182 /* Now convert the principal name into something human readable */ 183 princ_name = NULL; 184 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 185 if (krbret != 0) { 186 PAM_LOG("Error krb5_unparse_name(): %s", 187 krb5_get_err_text(pam_context, krbret)); 188 PAM_VERBOSE_ERROR("Kerberos 5 error"); 189 retval = PAM_SERVICE_ERR; 190 goto cleanup2; 191 } 192 193 PAM_LOG("Got principal: %s", princ_name); 194 195 /* Get password */ 196 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT); 197 if (retval != PAM_SUCCESS) 198 goto cleanup2; 199 200 PAM_LOG("Got password"); 201 202 /* Verify the local user exists (AFTER getting the password) */ 203 if (strchr(user, '@')) { 204 /* get a local account name for this principal */ 205 krbret = krb5_aname_to_localname(pam_context, princ, 206 sizeof(luser), luser); 207 if (krbret != 0) { 208 PAM_VERBOSE_ERROR("Kerberos 5 error"); 209 PAM_LOG("Error krb5_aname_to_localname(): %s", 210 krb5_get_err_text(pam_context, krbret)); 211 retval = PAM_USER_UNKNOWN; 212 goto cleanup2; 213 } 214 215 retval = pam_set_item(pamh, PAM_USER, luser); 216 if (retval != PAM_SUCCESS) 217 goto cleanup2; 218 219 PAM_LOG("PAM_USER Redone"); 220 } 221 222 pwd = getpwnam(user); 223 if (pwd == NULL) { 224 retval = PAM_USER_UNKNOWN; 225 goto cleanup2; 226 } 227 228 PAM_LOG("Done getpwnam()"); 229 230 /* Get a TGT */ 231 memset(&creds, 0, sizeof(krb5_creds)); 232 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 233 pass, NULL, pamh, 0, NULL, &opts); 234 if (krbret != 0) { 235 PAM_VERBOSE_ERROR("Kerberos 5 error"); 236 PAM_LOG("Error krb5_get_init_creds_password(): %s", 237 krb5_get_err_text(pam_context, krbret)); 238 retval = PAM_AUTH_ERR; 239 goto cleanup2; 240 } 241 242 PAM_LOG("Got TGT"); 243 244 /* Generate a temporary cache */ 245 krbret = krb5_cc_gen_new(pam_context, &krb5_mcc_ops, &ccache); 246 if (krbret != 0) { 247 PAM_VERBOSE_ERROR("Kerberos 5 error"); 248 PAM_LOG("Error krb5_cc_gen_new(): %s", 249 krb5_get_err_text(pam_context, krbret)); 250 retval = PAM_SERVICE_ERR; 251 goto cleanup; 252 } 253 krbret = krb5_cc_initialize(pam_context, ccache, princ); 254 if (krbret != 0) { 255 PAM_VERBOSE_ERROR("Kerberos 5 error"); 256 PAM_LOG("Error krb5_cc_initialize(): %s", 257 krb5_get_err_text(pam_context, krbret)); 258 retval = PAM_SERVICE_ERR; 259 goto cleanup; 260 } 261 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 262 if (krbret != 0) { 263 PAM_VERBOSE_ERROR("Kerberos 5 error"); 264 PAM_LOG("Error krb5_cc_store_cred(): %s", 265 krb5_get_err_text(pam_context, krbret)); 266 krb5_cc_destroy(pam_context, ccache); 267 retval = PAM_SERVICE_ERR; 268 goto cleanup; 269 } 270 271 PAM_LOG("Credentials stashed"); 272 273 /* Verify them */ 274 if ((srvdup = strdup(service)) == NULL) { 275 retval = PAM_BUF_ERR; 276 goto cleanup; 277 } 278 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 279 openpam_get_option(pamh, PAM_OPT_FORWARDABLE) ? 1 : 0); 280 free(srvdup); 281 if (krbret == -1) { 282 PAM_VERBOSE_ERROR("Kerberos 5 error"); 283 krb5_cc_destroy(pam_context, ccache); 284 retval = PAM_AUTH_ERR; 285 goto cleanup; 286 } 287 288 PAM_LOG("Credentials stash verified"); 289 290 retval = pam_get_data(pamh, "ccache", &ccache_data); 291 if (retval == PAM_SUCCESS) { 292 krb5_cc_destroy(pam_context, ccache); 293 PAM_VERBOSE_ERROR("Kerberos 5 error"); 294 retval = PAM_AUTH_ERR; 295 goto cleanup; 296 } 297 298 PAM_LOG("Credentials stash not pre-existing"); 299 300 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 301 ccache), krb5_cc_get_name(pam_context, ccache)); 302 if (ccache_name == NULL) { 303 PAM_VERBOSE_ERROR("Kerberos 5 error"); 304 retval = PAM_BUF_ERR; 305 goto cleanup; 306 } 307 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 308 if (retval != 0) { 309 krb5_cc_destroy(pam_context, ccache); 310 PAM_VERBOSE_ERROR("Kerberos 5 error"); 311 retval = PAM_SERVICE_ERR; 312 goto cleanup; 313 } 314 315 PAM_LOG("Credentials stash saved"); 316 317 cleanup: 318 krb5_free_cred_contents(pam_context, &creds); 319 PAM_LOG("Done cleanup"); 320 cleanup2: 321 krb5_free_principal(pam_context, princ); 322 PAM_LOG("Done cleanup2"); 323 cleanup3: 324 if (princ_name) 325 free(princ_name); 326 327 krb5_free_context(pam_context); 328 329 PAM_LOG("Done cleanup3"); 330 331 if (retval != PAM_SUCCESS) 332 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 333 334 return (retval); 335 } 336 337 PAM_EXTERN int 338 pam_sm_setcred(pam_handle_t *pamh, int flags, 339 int argc __unused, const char *argv[] __unused) 340 { 341 342 krb5_error_code krbret; 343 krb5_context pam_context; 344 krb5_principal princ; 345 krb5_creds creds; 346 krb5_ccache ccache_temp, ccache_perm; 347 krb5_cc_cursor cursor; 348 struct passwd *pwd = NULL; 349 int retval; 350 const char *cache_name, *q; 351 const void *user; 352 void *cache_data; 353 char *cache_name_buf = NULL, *p; 354 355 uid_t euid; 356 gid_t egid; 357 358 if (flags & PAM_DELETE_CRED) 359 return (PAM_SUCCESS); 360 361 if (flags & PAM_REFRESH_CRED) 362 return (PAM_SUCCESS); 363 364 if (flags & PAM_REINITIALIZE_CRED) 365 return (PAM_SUCCESS); 366 367 if (!(flags & PAM_ESTABLISH_CRED)) 368 return (PAM_SERVICE_ERR); 369 370 PAM_LOG("Establishing credentials"); 371 372 /* Get username */ 373 retval = pam_get_item(pamh, PAM_USER, &user); 374 if (retval != PAM_SUCCESS) 375 return (retval); 376 377 PAM_LOG("Got user: %s", (const char *)user); 378 379 krbret = krb5_init_context(&pam_context); 380 if (krbret != 0) { 381 PAM_LOG("Error krb5_init_context() failed"); 382 return (PAM_SERVICE_ERR); 383 } 384 385 PAM_LOG("Context initialised"); 386 387 euid = geteuid(); /* Usually 0 */ 388 egid = getegid(); 389 390 PAM_LOG("Got euid, egid: %d %d", euid, egid); 391 392 /* Retrieve the temporary cache */ 393 retval = pam_get_data(pamh, "ccache", &cache_data); 394 if (retval != PAM_SUCCESS) { 395 retval = PAM_CRED_UNAVAIL; 396 goto cleanup3; 397 } 398 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 399 if (krbret != 0) { 400 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 401 krb5_get_err_text(pam_context, krbret)); 402 retval = PAM_SERVICE_ERR; 403 goto cleanup3; 404 } 405 406 /* Get the uid. This should exist. */ 407 pwd = getpwnam(user); 408 if (pwd == NULL) { 409 retval = PAM_USER_UNKNOWN; 410 goto cleanup3; 411 } 412 413 PAM_LOG("Done getpwnam()"); 414 415 /* Avoid following a symlink as root */ 416 if (setegid(pwd->pw_gid)) { 417 retval = PAM_SERVICE_ERR; 418 goto cleanup3; 419 } 420 if (seteuid(pwd->pw_uid)) { 421 retval = PAM_SERVICE_ERR; 422 goto cleanup3; 423 } 424 425 PAM_LOG("Done setegid() & seteuid()"); 426 427 /* Get the cache name */ 428 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 429 if (cache_name == NULL) { 430 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 431 cache_name = cache_name_buf; 432 } 433 434 p = calloc(PATH_MAX + 16, sizeof(char)); 435 q = cache_name; 436 437 if (p == NULL) { 438 PAM_LOG("Error malloc(): failure"); 439 retval = PAM_BUF_ERR; 440 goto cleanup3; 441 } 442 cache_name = p; 443 444 /* convert %u and %p */ 445 while (*q) { 446 if (*q == '%') { 447 q++; 448 if (*q == 'u') { 449 sprintf(p, "%d", pwd->pw_uid); 450 p += strlen(p); 451 } 452 else if (*q == 'p') { 453 sprintf(p, "%d", getpid()); 454 p += strlen(p); 455 } 456 else { 457 /* Not a special token */ 458 *p++ = '%'; 459 q--; 460 } 461 q++; 462 } 463 else { 464 *p++ = *q++; 465 } 466 } 467 468 PAM_LOG("Got cache_name: %s", cache_name); 469 470 /* Initialize the new ccache */ 471 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 472 if (krbret != 0) { 473 PAM_LOG("Error krb5_cc_get_principal(): %s", 474 krb5_get_err_text(pam_context, krbret)); 475 retval = PAM_SERVICE_ERR; 476 goto cleanup3; 477 } 478 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 479 if (krbret != 0) { 480 PAM_LOG("Error krb5_cc_resolve(): %s", 481 krb5_get_err_text(pam_context, krbret)); 482 retval = PAM_SERVICE_ERR; 483 goto cleanup2; 484 } 485 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 486 if (krbret != 0) { 487 PAM_LOG("Error krb5_cc_initialize(): %s", 488 krb5_get_err_text(pam_context, krbret)); 489 retval = PAM_SERVICE_ERR; 490 goto cleanup2; 491 } 492 493 PAM_LOG("Cache initialised"); 494 495 /* Prepare for iteration over creds */ 496 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 497 if (krbret != 0) { 498 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 499 krb5_get_err_text(pam_context, krbret)); 500 krb5_cc_destroy(pam_context, ccache_perm); 501 retval = PAM_SERVICE_ERR; 502 goto cleanup2; 503 } 504 505 PAM_LOG("Prepared for iteration"); 506 507 /* Copy the creds (should be two of them) */ 508 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 509 &cursor, &creds) == 0)) { 510 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 511 if (krbret != 0) { 512 PAM_LOG("Error krb5_cc_store_cred(): %s", 513 krb5_get_err_text(pam_context, krbret)); 514 krb5_cc_destroy(pam_context, ccache_perm); 515 krb5_free_cred_contents(pam_context, &creds); 516 retval = PAM_SERVICE_ERR; 517 goto cleanup2; 518 } 519 krb5_free_cred_contents(pam_context, &creds); 520 PAM_LOG("Iteration"); 521 } 522 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 523 524 PAM_LOG("Done iterating"); 525 526 if (strstr(cache_name, "FILE:") == cache_name) { 527 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 528 PAM_LOG("Error chown(): %s", strerror(errno)); 529 krb5_cc_destroy(pam_context, ccache_perm); 530 retval = PAM_SERVICE_ERR; 531 goto cleanup2; 532 } 533 PAM_LOG("Done chown()"); 534 535 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 536 PAM_LOG("Error chmod(): %s", strerror(errno)); 537 krb5_cc_destroy(pam_context, ccache_perm); 538 retval = PAM_SERVICE_ERR; 539 goto cleanup2; 540 } 541 PAM_LOG("Done chmod()"); 542 } 543 544 krb5_cc_close(pam_context, ccache_perm); 545 546 PAM_LOG("Cache closed"); 547 548 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 549 if (retval != PAM_SUCCESS) { 550 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 551 krb5_cc_destroy(pam_context, ccache_perm); 552 retval = PAM_SERVICE_ERR; 553 goto cleanup2; 554 } 555 556 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 557 558 cleanup2: 559 krb5_free_principal(pam_context, princ); 560 PAM_LOG("Done cleanup2"); 561 cleanup3: 562 krb5_free_context(pam_context); 563 PAM_LOG("Done cleanup3"); 564 565 seteuid(euid); 566 setegid(egid); 567 568 PAM_LOG("Done seteuid() & setegid()"); 569 570 if (cache_name_buf != NULL) 571 free(cache_name_buf); 572 573 return (retval); 574 } 575 576 /* 577 * account management 578 */ 579 PAM_EXTERN int 580 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 581 int argc __unused, const char *argv[] __unused) 582 { 583 krb5_error_code krbret; 584 krb5_context pam_context; 585 krb5_ccache ccache; 586 krb5_principal princ; 587 int retval; 588 const void *user; 589 void *ccache_name; 590 591 retval = pam_get_item(pamh, PAM_USER, &user); 592 if (retval != PAM_SUCCESS) 593 return (retval); 594 595 PAM_LOG("Got user: %s", (const char *)user); 596 597 retval = pam_get_data(pamh, "ccache", &ccache_name); 598 if (retval != PAM_SUCCESS) 599 return (PAM_SUCCESS); 600 601 PAM_LOG("Got credentials"); 602 603 krbret = krb5_init_context(&pam_context); 604 if (krbret != 0) { 605 PAM_LOG("Error krb5_init_context() failed"); 606 return (PAM_PERM_DENIED); 607 } 608 609 PAM_LOG("Context initialised"); 610 611 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 612 if (krbret != 0) { 613 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 614 krb5_get_err_text(pam_context, krbret)); 615 krb5_free_context(pam_context); 616 return (PAM_PERM_DENIED); 617 } 618 619 PAM_LOG("Got ccache %s", (const char *)ccache_name); 620 621 622 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 623 if (krbret != 0) { 624 PAM_LOG("Error krb5_cc_get_principal(): %s", 625 krb5_get_err_text(pam_context, krbret)); 626 retval = PAM_PERM_DENIED;; 627 goto cleanup; 628 } 629 630 PAM_LOG("Got principal"); 631 632 if (krb5_kuserok(pam_context, princ, (const char *)user)) 633 retval = PAM_SUCCESS; 634 else 635 retval = PAM_PERM_DENIED; 636 krb5_free_principal(pam_context, princ); 637 638 PAM_LOG("Done kuserok()"); 639 640 cleanup: 641 krb5_free_context(pam_context); 642 PAM_LOG("Done cleanup"); 643 644 return (retval); 645 646 } 647 648 /* 649 * password management 650 */ 651 PAM_EXTERN int 652 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 653 int argc __unused, const char *argv[] __unused) 654 { 655 krb5_error_code krbret; 656 krb5_context pam_context; 657 krb5_creds creds; 658 krb5_principal princ; 659 krb5_get_init_creds_opt opts; 660 krb5_data result_code_string, result_string; 661 int result_code, retval; 662 const char *pass; 663 const void *user; 664 char *princ_name, *passdup; 665 666 if (!(flags & PAM_UPDATE_AUTHTOK)) 667 return (PAM_AUTHTOK_ERR); 668 669 retval = pam_get_item(pamh, PAM_USER, &user); 670 if (retval != PAM_SUCCESS) 671 return (retval); 672 673 PAM_LOG("Got user: %s", (const char *)user); 674 675 krbret = krb5_init_context(&pam_context); 676 if (krbret != 0) { 677 PAM_LOG("Error krb5_init_context() failed"); 678 return (PAM_SERVICE_ERR); 679 } 680 681 PAM_LOG("Context initialised"); 682 683 krb5_get_init_creds_opt_init(&opts); 684 685 PAM_LOG("Credentials options initialised"); 686 687 /* Get principal name */ 688 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 689 if (krbret != 0) { 690 PAM_LOG("Error krb5_parse_name(): %s", 691 krb5_get_err_text(pam_context, krbret)); 692 retval = PAM_USER_UNKNOWN; 693 goto cleanup3; 694 } 695 696 /* Now convert the principal name into something human readable */ 697 princ_name = NULL; 698 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 699 if (krbret != 0) { 700 PAM_LOG("Error krb5_unparse_name(): %s", 701 krb5_get_err_text(pam_context, krbret)); 702 retval = PAM_SERVICE_ERR; 703 goto cleanup2; 704 } 705 706 PAM_LOG("Got principal: %s", princ_name); 707 708 /* Get password */ 709 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT); 710 if (retval != PAM_SUCCESS) 711 goto cleanup2; 712 713 PAM_LOG("Got password"); 714 715 memset(&creds, 0, sizeof(krb5_creds)); 716 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 717 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 718 if (krbret != 0) { 719 PAM_LOG("Error krb5_get_init_creds_password(): %s", 720 krb5_get_err_text(pam_context, krbret)); 721 retval = PAM_AUTH_ERR; 722 goto cleanup2; 723 } 724 725 PAM_LOG("Credentials established"); 726 727 /* Now get the new password */ 728 for (;;) { 729 retval = pam_get_authtok(pamh, 730 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 731 if (retval != PAM_TRY_AGAIN) 732 break; 733 pam_error(pamh, "Mismatch; try again, EOF to quit."); 734 } 735 if (retval != PAM_SUCCESS) 736 goto cleanup; 737 738 PAM_LOG("Got new password"); 739 740 /* Change it */ 741 if ((passdup = strdup(pass)) == NULL) { 742 retval = PAM_BUF_ERR; 743 goto cleanup; 744 } 745 krbret = krb5_change_password(pam_context, &creds, passdup, 746 &result_code, &result_code_string, &result_string); 747 free(passdup); 748 if (krbret != 0) { 749 PAM_LOG("Error krb5_change_password(): %s", 750 krb5_get_err_text(pam_context, krbret)); 751 retval = PAM_AUTHTOK_ERR; 752 goto cleanup; 753 } 754 if (result_code) { 755 PAM_LOG("Error krb5_change_password(): (result_code)"); 756 retval = PAM_AUTHTOK_ERR; 757 goto cleanup; 758 } 759 760 PAM_LOG("Password changed"); 761 762 if (result_string.data) 763 free(result_string.data); 764 if (result_code_string.data) 765 free(result_code_string.data); 766 767 cleanup: 768 krb5_free_cred_contents(pam_context, &creds); 769 PAM_LOG("Done cleanup"); 770 cleanup2: 771 krb5_free_principal(pam_context, princ); 772 PAM_LOG("Done cleanup2"); 773 cleanup3: 774 if (princ_name) 775 free(princ_name); 776 777 krb5_free_context(pam_context); 778 779 PAM_LOG("Done cleanup3"); 780 781 return (retval); 782 } 783 784 PAM_MODULE_ENTRY("pam_krb5"); 785 786 /* 787 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 788 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 789 * for Debian. 790 * 791 * Verify the Kerberos ticket-granting ticket just retrieved for the 792 * user. If the Kerberos server doesn't respond, assume the user is 793 * trying to fake us out (since we DID just get a TGT from what is 794 * supposedly our KDC). If the host/<host> service is unknown (i.e., 795 * the local keytab doesn't have it), and we cannot find another 796 * service we do have, let her in. 797 * 798 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 799 */ 800 /* ARGSUSED */ 801 static int 802 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 803 char *pam_service, int debug) 804 { 805 krb5_error_code retval; 806 krb5_principal princ; 807 krb5_keyblock *keyblock; 808 krb5_data packet; 809 krb5_auth_context auth_context; 810 char phost[BUFSIZ]; 811 const char *services[3], **service; 812 813 packet.data = 0; 814 815 /* If possible we want to try and verify the ticket we have 816 * received against a keytab. We will try multiple service 817 * principals, including at least the host principal and the PAM 818 * service principal. The host principal is preferred because access 819 * to that key is generally sufficient to compromise root, while the 820 * service key for this PAM service may be less carefully guarded. 821 * It is important to check the keytab first before the KDC so we do 822 * not get spoofed by a fake KDC. 823 */ 824 services[0] = "host"; 825 services[1] = pam_service; 826 services[2] = NULL; 827 keyblock = 0; 828 retval = -1; 829 for (service = &services[0]; *service != NULL; service++) { 830 retval = krb5_sname_to_principal(context, NULL, *service, 831 KRB5_NT_SRV_HST, &princ); 832 if (retval != 0) { 833 if (debug) 834 syslog(LOG_DEBUG, 835 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 836 "krb5_sname_to_principal()", 837 krb5_get_err_text(context, retval)); 838 return -1; 839 } 840 841 /* Extract the name directly. */ 842 strncpy(phost, compat_princ_component(context, princ, 1), 843 BUFSIZ); 844 phost[BUFSIZ - 1] = '\0'; 845 846 /* 847 * Do we have service/<host> keys? 848 * (use default/configured keytab, kvno IGNORE_VNO to get the 849 * first match, and ignore enctype.) 850 */ 851 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 852 &keyblock); 853 if (retval != 0) 854 continue; 855 break; 856 } 857 if (retval != 0) { /* failed to find key */ 858 /* Keytab or service key does not exist */ 859 if (debug) 860 syslog(LOG_DEBUG, 861 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 862 "krb5_kt_read_service_key()", 863 krb5_get_err_text(context, retval)); 864 retval = 0; 865 goto cleanup; 866 } 867 if (keyblock) 868 krb5_free_keyblock(context, keyblock); 869 870 /* Talk to the kdc and construct the ticket. */ 871 auth_context = NULL; 872 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 873 NULL, ccache, &packet); 874 if (auth_context) { 875 krb5_auth_con_free(context, auth_context); 876 auth_context = NULL; /* setup for rd_req */ 877 } 878 if (retval) { 879 if (debug) 880 syslog(LOG_DEBUG, 881 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 882 "krb5_mk_req()", 883 krb5_get_err_text(context, retval)); 884 retval = -1; 885 goto cleanup; 886 } 887 888 /* Try to use the ticket. */ 889 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 890 NULL, NULL); 891 if (retval) { 892 if (debug) 893 syslog(LOG_DEBUG, 894 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 895 "krb5_rd_req()", 896 krb5_get_err_text(context, retval)); 897 retval = -1; 898 } 899 else 900 retval = 1; 901 902 cleanup: 903 if (packet.data) 904 compat_free_data_contents(context, &packet); 905 krb5_free_principal(context, princ); 906 return retval; 907 } 908 909 /* Free the memory for cache_name. Called by pam_end() */ 910 /* ARGSUSED */ 911 static void 912 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 913 { 914 krb5_context pam_context; 915 krb5_ccache ccache; 916 krb5_error_code krbret; 917 918 if (krb5_init_context(&pam_context)) 919 return; 920 921 krbret = krb5_cc_resolve(pam_context, data, &ccache); 922 if (krbret == 0) 923 krb5_cc_destroy(pam_context, ccache); 924 krb5_free_context(pam_context); 925 free(data); 926 } 927 928 #ifdef COMPAT_HEIMDAL 929 #ifdef COMPAT_MIT 930 #error This cannot be MIT and Heimdal compatible! 931 #endif 932 #endif 933 934 #ifndef COMPAT_HEIMDAL 935 #ifndef COMPAT_MIT 936 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 937 #endif 938 #endif 939 940 #ifdef COMPAT_HEIMDAL 941 /* ARGSUSED */ 942 static const char * 943 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 944 { 945 return princ->name.name_string.val[n]; 946 } 947 948 /* ARGSUSED */ 949 static void 950 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 951 { 952 krb5_xfree(data->data); 953 } 954 #endif 955 956 #ifdef COMPAT_MIT 957 static const char * 958 compat_princ_component(krb5_context context, krb5_principal princ, int n) 959 { 960 return krb5_princ_component(context, princ, n)->data; 961 } 962 963 static void 964 compat_free_data_contents(krb5_context context, krb5_data * data) 965 { 966 krb5_free_data_contents(context, data); 967 } 968 #endif 969
Indexes created Mon Sep 29 21:09:56 GMT 2025