pam_krb5.c revision 1.6
1 /* $NetBSD: pam_krb5.c,v 1.6 2005/02/26 18:25:28 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 1.6 2005/02/26 18:25:28 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 "%s's 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 char password_prompt[80]; 120 121 retval = pam_get_user(pamh, &user, USER_PROMPT); 122 if (retval != PAM_SUCCESS) 123 return (retval); 124 125 PAM_LOG("Got user: %s", user); 126 127 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 128 if (retval != PAM_SUCCESS) 129 return (retval); 130 131 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 132 133 service = NULL; 134 pam_get_item(pamh, PAM_SERVICE, &service); 135 if (service == NULL) 136 service = "unknown"; 137 138 PAM_LOG("Got service: %s", (const char *)service); 139 140 krbret = krb5_init_context(&pam_context); 141 if (krbret != 0) { 142 PAM_VERBOSE_ERROR("Kerberos 5 error"); 143 return (PAM_SERVICE_ERR); 144 } 145 146 PAM_LOG("Context initialised"); 147 148 krb5_get_init_creds_opt_init(&opts); 149 150 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 151 krb5_get_init_creds_opt_set_forwardable(&opts, 1); 152 153 PAM_LOG("Credentials initialised"); 154 155 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 156 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 157 PAM_VERBOSE_ERROR("Kerberos 5 error"); 158 retval = PAM_SERVICE_ERR; 159 goto cleanup3; 160 } 161 162 PAM_LOG("Done krb5_cc_register()"); 163 164 /* Get principal name */ 165 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 166 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 167 else 168 principal = strdup(user); 169 170 PAM_LOG("Created principal: %s", principal); 171 172 krbret = krb5_parse_name(pam_context, principal, &princ); 173 free(principal); 174 if (krbret != 0) { 175 PAM_LOG("Error krb5_parse_name(): %s", 176 krb5_get_err_text(pam_context, krbret)); 177 PAM_VERBOSE_ERROR("Kerberos 5 error"); 178 retval = PAM_SERVICE_ERR; 179 goto cleanup3; 180 } 181 182 PAM_LOG("Done krb5_parse_name()"); 183 184 /* Now convert the principal name into something human readable */ 185 princ_name = NULL; 186 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 187 if (krbret != 0) { 188 PAM_LOG("Error krb5_unparse_name(): %s", 189 krb5_get_err_text(pam_context, krbret)); 190 PAM_VERBOSE_ERROR("Kerberos 5 error"); 191 retval = PAM_SERVICE_ERR; 192 goto cleanup2; 193 } 194 195 PAM_LOG("Got principal: %s", princ_name); 196 197 /* Get password */ 198 (void) snprintf(password_prompt, sizeof(password_prompt), 199 PASSWORD_PROMPT, princ_name); 200 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, password_prompt); 201 if (retval != PAM_SUCCESS) 202 goto cleanup2; 203 204 PAM_LOG("Got password"); 205 206 /* Verify the local user exists (AFTER getting the password) */ 207 if (strchr(user, '@')) { 208 /* get a local account name for this principal */ 209 krbret = krb5_aname_to_localname(pam_context, princ, 210 sizeof(luser), luser); 211 if (krbret != 0) { 212 PAM_VERBOSE_ERROR("Kerberos 5 error"); 213 PAM_LOG("Error krb5_aname_to_localname(): %s", 214 krb5_get_err_text(pam_context, krbret)); 215 retval = PAM_USER_UNKNOWN; 216 goto cleanup2; 217 } 218 219 retval = pam_set_item(pamh, PAM_USER, luser); 220 if (retval != PAM_SUCCESS) 221 goto cleanup2; 222 223 PAM_LOG("PAM_USER Redone"); 224 } 225 226 pwd = getpwnam(user); 227 if (pwd == NULL) { 228 retval = PAM_USER_UNKNOWN; 229 goto cleanup2; 230 } 231 232 PAM_LOG("Done getpwnam()"); 233 234 /* Get a TGT */ 235 memset(&creds, 0, sizeof(krb5_creds)); 236 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 237 pass, NULL, pamh, 0, NULL, &opts); 238 if (krbret != 0) { 239 PAM_VERBOSE_ERROR("Kerberos 5 error"); 240 PAM_LOG("Error krb5_get_init_creds_password(): %s", 241 krb5_get_err_text(pam_context, krbret)); 242 retval = PAM_AUTH_ERR; 243 goto cleanup2; 244 } 245 246 PAM_LOG("Got TGT"); 247 248 /* Generate a temporary cache */ 249 krbret = krb5_cc_gen_new(pam_context, &krb5_mcc_ops, &ccache); 250 if (krbret != 0) { 251 PAM_VERBOSE_ERROR("Kerberos 5 error"); 252 PAM_LOG("Error krb5_cc_gen_new(): %s", 253 krb5_get_err_text(pam_context, krbret)); 254 retval = PAM_SERVICE_ERR; 255 goto cleanup; 256 } 257 krbret = krb5_cc_initialize(pam_context, ccache, princ); 258 if (krbret != 0) { 259 PAM_VERBOSE_ERROR("Kerberos 5 error"); 260 PAM_LOG("Error krb5_cc_initialize(): %s", 261 krb5_get_err_text(pam_context, krbret)); 262 retval = PAM_SERVICE_ERR; 263 goto cleanup; 264 } 265 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 266 if (krbret != 0) { 267 PAM_VERBOSE_ERROR("Kerberos 5 error"); 268 PAM_LOG("Error krb5_cc_store_cred(): %s", 269 krb5_get_err_text(pam_context, krbret)); 270 krb5_cc_destroy(pam_context, ccache); 271 retval = PAM_SERVICE_ERR; 272 goto cleanup; 273 } 274 275 PAM_LOG("Credentials stashed"); 276 277 /* Verify them */ 278 if ((srvdup = strdup(service)) == NULL) { 279 retval = PAM_BUF_ERR; 280 goto cleanup; 281 } 282 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 283 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 284 free(srvdup); 285 if (krbret == -1) { 286 PAM_VERBOSE_ERROR("Kerberos 5 error"); 287 krb5_cc_destroy(pam_context, ccache); 288 retval = PAM_AUTH_ERR; 289 goto cleanup; 290 } 291 292 PAM_LOG("Credentials stash verified"); 293 294 retval = pam_get_data(pamh, "ccache", &ccache_data); 295 if (retval == PAM_SUCCESS) { 296 krb5_cc_destroy(pam_context, ccache); 297 PAM_VERBOSE_ERROR("Kerberos 5 error"); 298 retval = PAM_AUTH_ERR; 299 goto cleanup; 300 } 301 302 PAM_LOG("Credentials stash not pre-existing"); 303 304 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 305 ccache), krb5_cc_get_name(pam_context, ccache)); 306 if (ccache_name == NULL) { 307 PAM_VERBOSE_ERROR("Kerberos 5 error"); 308 retval = PAM_BUF_ERR; 309 goto cleanup; 310 } 311 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 312 if (retval != 0) { 313 krb5_cc_destroy(pam_context, ccache); 314 PAM_VERBOSE_ERROR("Kerberos 5 error"); 315 retval = PAM_SERVICE_ERR; 316 goto cleanup; 317 } 318 319 PAM_LOG("Credentials stash saved"); 320 321 cleanup: 322 krb5_free_cred_contents(pam_context, &creds); 323 PAM_LOG("Done cleanup"); 324 cleanup2: 325 krb5_free_principal(pam_context, princ); 326 PAM_LOG("Done cleanup2"); 327 cleanup3: 328 if (princ_name) 329 free(princ_name); 330 331 krb5_free_context(pam_context); 332 333 PAM_LOG("Done cleanup3"); 334 335 if (retval != PAM_SUCCESS) 336 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 337 338 return (retval); 339 } 340 341 PAM_EXTERN int 342 pam_sm_setcred(pam_handle_t *pamh, int flags, 343 int argc __unused, const char *argv[] __unused) 344 { 345 346 krb5_error_code krbret; 347 krb5_context pam_context; 348 krb5_principal princ; 349 krb5_creds creds; 350 krb5_ccache ccache_temp, ccache_perm; 351 krb5_cc_cursor cursor; 352 struct passwd *pwd = NULL; 353 int retval; 354 const char *cache_name, *q; 355 const void *user; 356 void *cache_data; 357 char *cache_name_buf = NULL, *p; 358 359 uid_t euid; 360 gid_t egid; 361 362 if (flags & PAM_DELETE_CRED) 363 return (PAM_SUCCESS); 364 365 if (flags & PAM_REFRESH_CRED) 366 return (PAM_SUCCESS); 367 368 if (flags & PAM_REINITIALIZE_CRED) 369 return (PAM_SUCCESS); 370 371 if (!(flags & PAM_ESTABLISH_CRED)) 372 return (PAM_SERVICE_ERR); 373 374 /* If a persistent cache isn't desired, stop now. */ 375 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE)) 376 return (PAM_SUCCESS); 377 378 PAM_LOG("Establishing credentials"); 379 380 /* Get username */ 381 retval = pam_get_item(pamh, PAM_USER, &user); 382 if (retval != PAM_SUCCESS) 383 return (retval); 384 385 PAM_LOG("Got user: %s", (const char *)user); 386 387 krbret = krb5_init_context(&pam_context); 388 if (krbret != 0) { 389 PAM_LOG("Error krb5_init_context() failed"); 390 return (PAM_SERVICE_ERR); 391 } 392 393 PAM_LOG("Context initialised"); 394 395 euid = geteuid(); /* Usually 0 */ 396 egid = getegid(); 397 398 PAM_LOG("Got euid, egid: %d %d", euid, egid); 399 400 /* Retrieve the temporary cache */ 401 retval = pam_get_data(pamh, "ccache", &cache_data); 402 if (retval != PAM_SUCCESS) { 403 retval = PAM_CRED_UNAVAIL; 404 goto cleanup3; 405 } 406 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 407 if (krbret != 0) { 408 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 409 krb5_get_err_text(pam_context, krbret)); 410 retval = PAM_SERVICE_ERR; 411 goto cleanup3; 412 } 413 414 /* Get the uid. This should exist. */ 415 pwd = getpwnam(user); 416 if (pwd == NULL) { 417 retval = PAM_USER_UNKNOWN; 418 goto cleanup3; 419 } 420 421 PAM_LOG("Done getpwnam()"); 422 423 /* Avoid following a symlink as root */ 424 if (setegid(pwd->pw_gid)) { 425 retval = PAM_SERVICE_ERR; 426 goto cleanup3; 427 } 428 if (seteuid(pwd->pw_uid)) { 429 retval = PAM_SERVICE_ERR; 430 goto cleanup3; 431 } 432 433 PAM_LOG("Done setegid() & seteuid()"); 434 435 /* Get the cache name */ 436 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 437 if (cache_name == NULL) { 438 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 439 cache_name = cache_name_buf; 440 } 441 442 p = calloc(PATH_MAX + 16, sizeof(char)); 443 q = cache_name; 444 445 if (p == NULL) { 446 PAM_LOG("Error malloc(): failure"); 447 retval = PAM_BUF_ERR; 448 goto cleanup3; 449 } 450 cache_name = p; 451 452 /* convert %u and %p */ 453 while (*q) { 454 if (*q == '%') { 455 q++; 456 if (*q == 'u') { 457 sprintf(p, "%d", pwd->pw_uid); 458 p += strlen(p); 459 } 460 else if (*q == 'p') { 461 sprintf(p, "%d", getpid()); 462 p += strlen(p); 463 } 464 else { 465 /* Not a special token */ 466 *p++ = '%'; 467 q--; 468 } 469 q++; 470 } 471 else { 472 *p++ = *q++; 473 } 474 } 475 476 PAM_LOG("Got cache_name: %s", cache_name); 477 478 /* Initialize the new ccache */ 479 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 480 if (krbret != 0) { 481 PAM_LOG("Error krb5_cc_get_principal(): %s", 482 krb5_get_err_text(pam_context, krbret)); 483 retval = PAM_SERVICE_ERR; 484 goto cleanup3; 485 } 486 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 487 if (krbret != 0) { 488 PAM_LOG("Error krb5_cc_resolve(): %s", 489 krb5_get_err_text(pam_context, krbret)); 490 retval = PAM_SERVICE_ERR; 491 goto cleanup2; 492 } 493 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 494 if (krbret != 0) { 495 PAM_LOG("Error krb5_cc_initialize(): %s", 496 krb5_get_err_text(pam_context, krbret)); 497 retval = PAM_SERVICE_ERR; 498 goto cleanup2; 499 } 500 501 PAM_LOG("Cache initialised"); 502 503 /* Prepare for iteration over creds */ 504 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 505 if (krbret != 0) { 506 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 507 krb5_get_err_text(pam_context, krbret)); 508 krb5_cc_destroy(pam_context, ccache_perm); 509 retval = PAM_SERVICE_ERR; 510 goto cleanup2; 511 } 512 513 PAM_LOG("Prepared for iteration"); 514 515 /* Copy the creds (should be two of them) */ 516 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 517 &cursor, &creds) == 0)) { 518 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 519 if (krbret != 0) { 520 PAM_LOG("Error krb5_cc_store_cred(): %s", 521 krb5_get_err_text(pam_context, krbret)); 522 krb5_cc_destroy(pam_context, ccache_perm); 523 krb5_free_cred_contents(pam_context, &creds); 524 retval = PAM_SERVICE_ERR; 525 goto cleanup2; 526 } 527 krb5_free_cred_contents(pam_context, &creds); 528 PAM_LOG("Iteration"); 529 } 530 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 531 532 PAM_LOG("Done iterating"); 533 534 if (strstr(cache_name, "FILE:") == cache_name) { 535 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 536 PAM_LOG("Error chown(): %s", strerror(errno)); 537 krb5_cc_destroy(pam_context, ccache_perm); 538 retval = PAM_SERVICE_ERR; 539 goto cleanup2; 540 } 541 PAM_LOG("Done chown()"); 542 543 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 544 PAM_LOG("Error chmod(): %s", strerror(errno)); 545 krb5_cc_destroy(pam_context, ccache_perm); 546 retval = PAM_SERVICE_ERR; 547 goto cleanup2; 548 } 549 PAM_LOG("Done chmod()"); 550 } 551 552 krb5_cc_close(pam_context, ccache_perm); 553 554 PAM_LOG("Cache closed"); 555 556 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 557 if (retval != PAM_SUCCESS) { 558 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 559 krb5_cc_destroy(pam_context, ccache_perm); 560 retval = PAM_SERVICE_ERR; 561 goto cleanup2; 562 } 563 564 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 565 566 cleanup2: 567 krb5_free_principal(pam_context, princ); 568 PAM_LOG("Done cleanup2"); 569 cleanup3: 570 krb5_free_context(pam_context); 571 PAM_LOG("Done cleanup3"); 572 573 seteuid(euid); 574 setegid(egid); 575 576 PAM_LOG("Done seteuid() & setegid()"); 577 578 if (cache_name_buf != NULL) 579 free(cache_name_buf); 580 581 return (retval); 582 } 583 584 /* 585 * account management 586 */ 587 PAM_EXTERN int 588 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 589 int argc __unused, const char *argv[] __unused) 590 { 591 krb5_error_code krbret; 592 krb5_context pam_context; 593 krb5_ccache ccache; 594 krb5_principal princ; 595 int retval; 596 const void *user; 597 void *ccache_name; 598 599 retval = pam_get_item(pamh, PAM_USER, &user); 600 if (retval != PAM_SUCCESS) 601 return (retval); 602 603 PAM_LOG("Got user: %s", (const char *)user); 604 605 retval = pam_get_data(pamh, "ccache", &ccache_name); 606 if (retval != PAM_SUCCESS) 607 return (PAM_SUCCESS); 608 609 PAM_LOG("Got credentials"); 610 611 krbret = krb5_init_context(&pam_context); 612 if (krbret != 0) { 613 PAM_LOG("Error krb5_init_context() failed"); 614 return (PAM_PERM_DENIED); 615 } 616 617 PAM_LOG("Context initialised"); 618 619 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 620 if (krbret != 0) { 621 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 622 krb5_get_err_text(pam_context, krbret)); 623 krb5_free_context(pam_context); 624 return (PAM_PERM_DENIED); 625 } 626 627 PAM_LOG("Got ccache %s", (const char *)ccache_name); 628 629 630 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 631 if (krbret != 0) { 632 PAM_LOG("Error krb5_cc_get_principal(): %s", 633 krb5_get_err_text(pam_context, krbret)); 634 retval = PAM_PERM_DENIED;; 635 goto cleanup; 636 } 637 638 PAM_LOG("Got principal"); 639 640 if (krb5_kuserok(pam_context, princ, (const char *)user)) 641 retval = PAM_SUCCESS; 642 else 643 retval = PAM_PERM_DENIED; 644 krb5_free_principal(pam_context, princ); 645 646 PAM_LOG("Done kuserok()"); 647 648 cleanup: 649 krb5_free_context(pam_context); 650 PAM_LOG("Done cleanup"); 651 652 return (retval); 653 654 } 655 656 /* 657 * password management 658 */ 659 PAM_EXTERN int 660 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 661 int argc __unused, const char *argv[] __unused) 662 { 663 krb5_error_code krbret; 664 krb5_context pam_context; 665 krb5_creds creds; 666 krb5_principal princ; 667 krb5_get_init_creds_opt opts; 668 krb5_data result_code_string, result_string; 669 int result_code, retval; 670 const char *pass; 671 const void *user; 672 char *princ_name, *passdup; 673 char password_prompt[80]; 674 675 if (flags & PAM_PRELIM_CHECK) { 676 /* Nothing to do here. */ 677 return (PAM_SUCCESS); 678 } 679 680 if (!(flags & PAM_UPDATE_AUTHTOK)) { 681 PAM_LOG("Illegal flags argument"); 682 return (PAM_ABORT); 683 } 684 685 retval = pam_get_item(pamh, PAM_USER, &user); 686 if (retval != PAM_SUCCESS) 687 return (retval); 688 689 PAM_LOG("Got user: %s", (const char *)user); 690 691 krbret = krb5_init_context(&pam_context); 692 if (krbret != 0) { 693 PAM_LOG("Error krb5_init_context() failed"); 694 return (PAM_SERVICE_ERR); 695 } 696 697 PAM_LOG("Context initialised"); 698 699 krb5_get_init_creds_opt_init(&opts); 700 701 krb5_get_init_creds_opt_set_tkt_life(&opts, 300); 702 krb5_get_init_creds_opt_set_forwardable(&opts, FALSE); 703 krb5_get_init_creds_opt_set_proxiable(&opts, FALSE); 704 705 PAM_LOG("Credentials options initialised"); 706 707 /* Get principal name */ 708 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 709 if (krbret != 0) { 710 PAM_LOG("Error krb5_parse_name(): %s", 711 krb5_get_err_text(pam_context, krbret)); 712 retval = PAM_USER_UNKNOWN; 713 goto cleanup3; 714 } 715 716 /* Now convert the principal name into something human readable */ 717 princ_name = NULL; 718 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 719 if (krbret != 0) { 720 PAM_LOG("Error krb5_unparse_name(): %s", 721 krb5_get_err_text(pam_context, krbret)); 722 retval = PAM_SERVICE_ERR; 723 goto cleanup2; 724 } 725 726 PAM_LOG("Got principal: %s", princ_name); 727 728 /* Get password */ 729 (void) snprintf(password_prompt, sizeof(password_prompt), 730 PASSWORD_PROMPT, princ_name); 731 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt); 732 if (retval != PAM_SUCCESS) 733 goto cleanup2; 734 735 PAM_LOG("Got password"); 736 737 memset(&creds, 0, sizeof(krb5_creds)); 738 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 739 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 740 if (krbret != 0) { 741 PAM_LOG("Error krb5_get_init_creds_password(): %s", 742 krb5_get_err_text(pam_context, krbret)); 743 retval = PAM_AUTH_ERR; 744 goto cleanup2; 745 } 746 747 PAM_LOG("Credentials established"); 748 749 /* Now get the new password */ 750 for (;;) { 751 retval = pam_get_authtok(pamh, 752 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 753 if (retval != PAM_TRY_AGAIN) 754 break; 755 pam_error(pamh, "Mismatch; try again, EOF to quit."); 756 } 757 if (retval != PAM_SUCCESS) 758 goto cleanup; 759 760 PAM_LOG("Got new password"); 761 762 /* Change it */ 763 if ((passdup = strdup(pass)) == NULL) { 764 retval = PAM_BUF_ERR; 765 goto cleanup; 766 } 767 768 krb5_data_zero(&result_code_string); 769 krb5_data_zero(&result_string); 770 771 krbret = krb5_change_password(pam_context, &creds, passdup, 772 &result_code, &result_code_string, &result_string); 773 free(passdup); 774 if (krbret != 0) { 775 pam_error(pamh, "Unable to set password: %s", 776 krb5_get_err_text(pam_context, krbret)); 777 retval = PAM_AUTHTOK_ERR; 778 goto cleanup; 779 } 780 if (result_code) { 781 pam_info(pamh, "%s%s%.*s", 782 krb5_passwd_result_to_string(pam_context, result_code), 783 result_string.length > 0 ? ": " : "", 784 (int)result_string.length, 785 result_string.length > 0 ? (char *)result_string.data : ""); 786 retval = PAM_AUTHTOK_ERR; 787 } else { 788 PAM_LOG("Password changed"); 789 } 790 791 krb5_data_free(&result_string); 792 krb5_data_free(&result_code_string); 793 794 cleanup: 795 krb5_free_cred_contents(pam_context, &creds); 796 PAM_LOG("Done cleanup"); 797 cleanup2: 798 krb5_free_principal(pam_context, princ); 799 PAM_LOG("Done cleanup2"); 800 cleanup3: 801 if (princ_name) 802 free(princ_name); 803 804 krb5_free_context(pam_context); 805 806 PAM_LOG("Done cleanup3"); 807 808 return (retval); 809 } 810 811 PAM_MODULE_ENTRY("pam_krb5"); 812 813 /* 814 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 815 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 816 * for Debian. 817 * 818 * Verify the Kerberos ticket-granting ticket just retrieved for the 819 * user. If the Kerberos server doesn't respond, assume the user is 820 * trying to fake us out (since we DID just get a TGT from what is 821 * supposedly our KDC). If the host/<host> service is unknown (i.e., 822 * the local keytab doesn't have it), and we cannot find another 823 * service we do have, let her in. 824 * 825 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 826 */ 827 /* ARGSUSED */ 828 static int 829 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 830 char *pam_service, int debug) 831 { 832 krb5_error_code retval; 833 krb5_principal princ; 834 krb5_keyblock *keyblock; 835 krb5_data packet; 836 krb5_auth_context auth_context; 837 char phost[BUFSIZ]; 838 const char *services[3], **service; 839 840 packet.data = 0; 841 842 /* If possible we want to try and verify the ticket we have 843 * received against a keytab. We will try multiple service 844 * principals, including at least the host principal and the PAM 845 * service principal. The host principal is preferred because access 846 * to that key is generally sufficient to compromise root, while the 847 * service key for this PAM service may be less carefully guarded. 848 * It is important to check the keytab first before the KDC so we do 849 * not get spoofed by a fake KDC. 850 */ 851 services[0] = "host"; 852 services[1] = pam_service; 853 services[2] = NULL; 854 keyblock = 0; 855 retval = -1; 856 for (service = &services[0]; *service != NULL; service++) { 857 retval = krb5_sname_to_principal(context, NULL, *service, 858 KRB5_NT_SRV_HST, &princ); 859 if (retval != 0) { 860 if (debug) 861 syslog(LOG_DEBUG, 862 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 863 "krb5_sname_to_principal()", 864 krb5_get_err_text(context, retval)); 865 return -1; 866 } 867 868 /* Extract the name directly. */ 869 strncpy(phost, compat_princ_component(context, princ, 1), 870 BUFSIZ); 871 phost[BUFSIZ - 1] = '\0'; 872 873 /* 874 * Do we have service/<host> keys? 875 * (use default/configured keytab, kvno IGNORE_VNO to get the 876 * first match, and ignore enctype.) 877 */ 878 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 879 &keyblock); 880 if (retval != 0) 881 continue; 882 break; 883 } 884 if (retval != 0) { /* failed to find key */ 885 /* Keytab or service key does not exist */ 886 if (debug) 887 syslog(LOG_DEBUG, 888 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 889 "krb5_kt_read_service_key()", 890 krb5_get_err_text(context, retval)); 891 retval = 0; 892 goto cleanup; 893 } 894 if (keyblock) 895 krb5_free_keyblock(context, keyblock); 896 897 /* Talk to the kdc and construct the ticket. */ 898 auth_context = NULL; 899 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 900 NULL, ccache, &packet); 901 if (auth_context) { 902 krb5_auth_con_free(context, auth_context); 903 auth_context = NULL; /* setup for rd_req */ 904 } 905 if (retval) { 906 if (debug) 907 syslog(LOG_DEBUG, 908 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 909 "krb5_mk_req()", 910 krb5_get_err_text(context, retval)); 911 retval = -1; 912 goto cleanup; 913 } 914 915 /* Try to use the ticket. */ 916 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 917 NULL, NULL); 918 if (retval) { 919 if (debug) 920 syslog(LOG_DEBUG, 921 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 922 "krb5_rd_req()", 923 krb5_get_err_text(context, retval)); 924 retval = -1; 925 } 926 else 927 retval = 1; 928 929 cleanup: 930 if (packet.data) 931 compat_free_data_contents(context, &packet); 932 krb5_free_principal(context, princ); 933 return retval; 934 } 935 936 /* Free the memory for cache_name. Called by pam_end() */ 937 /* ARGSUSED */ 938 static void 939 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 940 { 941 krb5_context pam_context; 942 krb5_ccache ccache; 943 krb5_error_code krbret; 944 945 if (krb5_init_context(&pam_context)) 946 return; 947 948 krbret = krb5_cc_resolve(pam_context, data, &ccache); 949 if (krbret == 0) 950 krb5_cc_destroy(pam_context, ccache); 951 krb5_free_context(pam_context); 952 free(data); 953 } 954 955 #ifdef COMPAT_HEIMDAL 956 #ifdef COMPAT_MIT 957 #error This cannot be MIT and Heimdal compatible! 958 #endif 959 #endif 960 961 #ifndef COMPAT_HEIMDAL 962 #ifndef COMPAT_MIT 963 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 964 #endif 965 #endif 966 967 #ifdef COMPAT_HEIMDAL 968 /* ARGSUSED */ 969 static const char * 970 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 971 { 972 return princ->name.name_string.val[n]; 973 } 974 975 /* ARGSUSED */ 976 static void 977 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 978 { 979 krb5_xfree(data->data); 980 } 981 #endif 982 983 #ifdef COMPAT_MIT 984 static const char * 985 compat_princ_component(krb5_context context, krb5_principal princ, int n) 986 { 987 return krb5_princ_component(context, princ, n)->data; 988 } 989 990 static void 991 compat_free_data_contents(krb5_context context, krb5_data * data) 992 { 993 krb5_free_data_contents(context, data); 994 } 995 #endif 996
Indexes created Mon Sep 29 21:09:56 GMT 2025