pam_krb5.c revision 239099
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., 2002-2005. 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: head/lib/libpam/modules/pam_krb5/pam_krb5.c 239099 2012-08-06 18:40:14Z dim $"); 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 79static int verify_krb_v5_tgt(krb5_context, krb5_ccache, char *, int); 80static void cleanup_cache(pam_handle_t *, void *, int); 81static const char *compat_princ_component(krb5_context, krb5_principal, int); 82static 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_DEBUG "debug" 90#define PAM_OPT_FORWARDABLE "forwardable" 91#define PAM_OPT_NO_CCACHE "no_ccache" 92#define PAM_OPT_NO_USER_CHECK "no_user_check" 93#define PAM_OPT_REUSE_CCACHE "reuse_ccache" 94#define PAM_OPT_NO_USER_CHECK "no_user_check" 95 96#define PAM_LOG_KRB5_ERR(ctx, rv, fmt, ...) \ 97 do { \ 98 const char *krb5msg = krb5_get_error_message(ctx, rv); \ 99 PAM_LOG(fmt ": %s", ##__VA_ARGS__, krb5msg); \ 100 krb5_free_error_message(ctx, krb5msg); \ 101 } while (0) 102 103/* 104 * authentication management 105 */ 106PAM_EXTERN int 107pam_sm_authenticate(pam_handle_t *pamh, int flags __unused, 108 int argc __unused, const char *argv[] __unused) 109{ 110 krb5_error_code krbret; 111 krb5_context pam_context; 112 krb5_creds creds; 113 krb5_principal princ; 114 krb5_ccache ccache; 115 krb5_get_init_creds_opt *opts; 116 struct passwd *pwd; 117 int retval; 118 const void *ccache_data; 119 const char *user, *pass; 120 const void *sourceuser, *service; 121 char *principal, *princ_name, *ccache_name, luser[32], *srvdup; 122 123 retval = pam_get_user(pamh, &user, USER_PROMPT); 124 if (retval != PAM_SUCCESS) 125 return (retval); 126 127 PAM_LOG("Got user: %s", user); 128 129 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 130 if (retval != PAM_SUCCESS) 131 return (retval); 132 133 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 134 135 service = NULL; 136 pam_get_item(pamh, PAM_SERVICE, &service); 137 if (service == NULL) 138 service = "unknown"; 139 140 PAM_LOG("Got service: %s", (const char *)service); 141 142 krbret = krb5_init_context(&pam_context); 143 if (krbret != 0) { 144 PAM_VERBOSE_ERROR("Kerberos 5 error"); 145 return (PAM_SERVICE_ERR); 146 } 147 148 PAM_LOG("Context initialised"); 149 150 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 151 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 152 PAM_VERBOSE_ERROR("Kerberos 5 error"); 153 retval = PAM_SERVICE_ERR; 154 goto cleanup3; 155 } 156 157 PAM_LOG("Done krb5_cc_register()"); 158 159 /* Get principal name */ 160 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 161 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 162 else 163 principal = strdup(user); 164 165 PAM_LOG("Created principal: %s", principal); 166 167 krbret = krb5_parse_name(pam_context, principal, &princ); 168 free(principal); 169 if (krbret != 0) { 170 PAM_LOG_KRB5_ERR(pam_context, krbret, "Error krb5_parse_name()"); 171 PAM_VERBOSE_ERROR("Kerberos 5 error"); 172 retval = PAM_SERVICE_ERR; 173 goto cleanup3; 174 } 175 176 PAM_LOG("Done krb5_parse_name()"); 177 178 /* Now convert the principal name into something human readable */ 179 princ_name = NULL; 180 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 181 if (krbret != 0) { 182 PAM_LOG_KRB5_ERR(pam_context, krbret, 183 "Error krb5_unparse_name()"); 184 PAM_VERBOSE_ERROR("Kerberos 5 error"); 185 retval = PAM_SERVICE_ERR; 186 goto cleanup2; 187 } 188 189 PAM_LOG("Got principal: %s", princ_name); 190 191 /* Get password */ 192 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, PASSWORD_PROMPT); 193 if (retval != PAM_SUCCESS) 194 goto cleanup2; 195 196 PAM_LOG("Got password"); 197 198 if (openpam_get_option(pamh, PAM_OPT_NO_USER_CHECK)) 199 PAM_LOG("Skipping local user check"); 200 else { 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_KRB5_ERR(pam_context, krbret, 210 "Error krb5_aname_to_localname()"); 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 if (!openpam_get_option(pamh, PAM_OPT_NO_USER_CHECK)) { 223 pwd = getpwnam(user); 224 if (pwd == NULL) { 225 retval = PAM_USER_UNKNOWN; 226 goto cleanup2; 227 } 228 } 229 230 PAM_LOG("Done getpwnam()"); 231 } 232 233 /* Initialize credentials request options. */ 234 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 235 if (krbret != 0) { 236 PAM_LOG_KRB5_ERR(pam_context, krbret, 237 "Error krb5_get_init_creds_opt_alloc()"); 238 PAM_VERBOSE_ERROR("Kerberos 5 error"); 239 retval = PAM_SERVICE_ERR; 240 goto cleanup2; 241 } 242 243 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 244 krb5_get_init_creds_opt_set_forwardable(opts, 1); 245 246 PAM_LOG("Credential options initialised"); 247 248 /* Get a TGT */ 249 memset(&creds, 0, sizeof(krb5_creds)); 250 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 251 pass, NULL, pamh, 0, NULL, opts); 252 krb5_get_init_creds_opt_free(pam_context, opts); 253 if (krbret != 0) { 254 PAM_VERBOSE_ERROR("Kerberos 5 error"); 255 PAM_LOG_KRB5_ERR(pam_context, krbret, 256 "Error krb5_get_init_creds_password()"); 257 retval = PAM_AUTH_ERR; 258 goto cleanup2; 259 } 260 261 PAM_LOG("Got TGT"); 262 263 /* Generate a temporary cache */ 264 krbret = krb5_cc_new_unique(pam_context, krb5_cc_type_memory, NULL, &ccache); 265 if (krbret != 0) { 266 PAM_VERBOSE_ERROR("Kerberos 5 error"); 267 PAM_LOG_KRB5_ERR(pam_context, krbret, 268 "Error krb5_cc_new_unique()"); 269 retval = PAM_SERVICE_ERR; 270 goto cleanup; 271 } 272 krbret = krb5_cc_initialize(pam_context, ccache, princ); 273 if (krbret != 0) { 274 PAM_VERBOSE_ERROR("Kerberos 5 error"); 275 PAM_LOG_KRB5_ERR(pam_context, krbret, 276 "Error krb5_cc_initialize()"); 277 retval = PAM_SERVICE_ERR; 278 goto cleanup; 279 } 280 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 281 if (krbret != 0) { 282 PAM_VERBOSE_ERROR("Kerberos 5 error"); 283 PAM_LOG_KRB5_ERR(pam_context, krbret, 284 "Error krb5_cc_store_cred()"); 285 krb5_cc_destroy(pam_context, ccache); 286 retval = PAM_SERVICE_ERR; 287 goto cleanup; 288 } 289 290 PAM_LOG("Credentials stashed"); 291 292 /* Verify them */ 293 if ((srvdup = strdup(service)) == NULL) { 294 retval = PAM_BUF_ERR; 295 goto cleanup; 296 } 297 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 298 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 299 free(srvdup); 300 if (krbret == -1) { 301 PAM_VERBOSE_ERROR("Kerberos 5 error"); 302 krb5_cc_destroy(pam_context, ccache); 303 retval = PAM_AUTH_ERR; 304 goto cleanup; 305 } 306 307 PAM_LOG("Credentials stash verified"); 308 309 retval = pam_get_data(pamh, "ccache", &ccache_data); 310 if (retval == PAM_SUCCESS) { 311 krb5_cc_destroy(pam_context, ccache); 312 PAM_VERBOSE_ERROR("Kerberos 5 error"); 313 retval = PAM_AUTH_ERR; 314 goto cleanup; 315 } 316 317 PAM_LOG("Credentials stash not pre-existing"); 318 319 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 320 ccache), krb5_cc_get_name(pam_context, ccache)); 321 if (ccache_name == NULL) { 322 PAM_VERBOSE_ERROR("Kerberos 5 error"); 323 retval = PAM_BUF_ERR; 324 goto cleanup; 325 } 326 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 327 if (retval != 0) { 328 krb5_cc_destroy(pam_context, ccache); 329 PAM_VERBOSE_ERROR("Kerberos 5 error"); 330 retval = PAM_SERVICE_ERR; 331 goto cleanup; 332 } 333 334 PAM_LOG("Credentials stash saved"); 335 336cleanup: 337 krb5_free_cred_contents(pam_context, &creds); 338 PAM_LOG("Done cleanup"); 339cleanup2: 340 krb5_free_principal(pam_context, princ); 341 if (princ_name) 342 free(princ_name); 343 PAM_LOG("Done cleanup2"); 344 345cleanup3: 346 krb5_free_context(pam_context); 347 348 PAM_LOG("Done cleanup3"); 349 350 if (retval != PAM_SUCCESS) 351 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 352 353 return (retval); 354} 355 356PAM_EXTERN int 357pam_sm_setcred(pam_handle_t *pamh, int flags, 358 int argc __unused, const char *argv[] __unused) 359{ 360#ifdef _FREEFALL_CONFIG 361 return (PAM_SUCCESS); 362#else 363 364 krb5_error_code krbret; 365 krb5_context pam_context; 366 krb5_principal princ; 367 krb5_creds creds; 368 krb5_ccache ccache_temp, ccache_perm; 369 krb5_cc_cursor cursor; 370 struct passwd *pwd = NULL; 371 int retval; 372 const char *cache_name, *q; 373 const void *user; 374 const void *cache_data; 375 char *cache_name_buf = NULL, *p; 376 377 uid_t euid; 378 gid_t egid; 379 380 if (flags & PAM_DELETE_CRED) 381 return (PAM_SUCCESS); 382 383 if (flags & PAM_REFRESH_CRED) 384 return (PAM_SUCCESS); 385 386 if (flags & PAM_REINITIALIZE_CRED) 387 return (PAM_SUCCESS); 388 389 if (!(flags & PAM_ESTABLISH_CRED)) 390 return (PAM_SERVICE_ERR); 391 392 /* If a persistent cache isn't desired, stop now. */ 393 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE) || 394 openpam_get_option(pamh, PAM_OPT_NO_USER_CHECK)) 395 return (PAM_SUCCESS); 396 397 PAM_LOG("Establishing credentials"); 398 399 /* Get username */ 400 retval = pam_get_item(pamh, PAM_USER, &user); 401 if (retval != PAM_SUCCESS) 402 return (retval); 403 404 PAM_LOG("Got user: %s", (const char *)user); 405 406 krbret = krb5_init_context(&pam_context); 407 if (krbret != 0) { 408 PAM_LOG("Error krb5_init_context() failed"); 409 return (PAM_SERVICE_ERR); 410 } 411 412 PAM_LOG("Context initialised"); 413 414 euid = geteuid(); /* Usually 0 */ 415 egid = getegid(); 416 417 PAM_LOG("Got euid, egid: %d %d", euid, egid); 418 419 /* Retrieve the temporary cache */ 420 retval = pam_get_data(pamh, "ccache", &cache_data); 421 if (retval != PAM_SUCCESS) { 422 retval = PAM_CRED_UNAVAIL; 423 goto cleanup3; 424 } 425 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 426 if (krbret != 0) { 427 PAM_LOG_KRB5_ERR(pam_context, krbret, 428 "Error krb5_cc_resolve(\"%s\")", (const char *)cache_data); 429 retval = PAM_SERVICE_ERR; 430 goto cleanup3; 431 } 432 433 /* Get the uid. This should exist. */ 434 pwd = getpwnam(user); 435 if (pwd == NULL) { 436 retval = PAM_USER_UNKNOWN; 437 goto cleanup3; 438 } 439 440 PAM_LOG("Done getpwnam()"); 441 442 /* Avoid following a symlink as root */ 443 if (setegid(pwd->pw_gid)) { 444 retval = PAM_SERVICE_ERR; 445 goto cleanup3; 446 } 447 if (seteuid(pwd->pw_uid)) { 448 retval = PAM_SERVICE_ERR; 449 goto cleanup3; 450 } 451 452 PAM_LOG("Done setegid() & seteuid()"); 453 454 /* Get the cache name */ 455 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 456 if (cache_name == NULL) { 457 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 458 cache_name = cache_name_buf; 459 } 460 461 p = calloc(PATH_MAX + 16, sizeof(char)); 462 q = cache_name; 463 464 if (p == NULL) { 465 PAM_LOG("Error malloc(): failure"); 466 retval = PAM_BUF_ERR; 467 goto cleanup3; 468 } 469 cache_name = p; 470 471 /* convert %u and %p */ 472 while (*q) { 473 if (*q == '%') { 474 q++; 475 if (*q == 'u') { 476 sprintf(p, "%d", pwd->pw_uid); 477 p += strlen(p); 478 } 479 else if (*q == 'p') { 480 sprintf(p, "%d", getpid()); 481 p += strlen(p); 482 } 483 else { 484 /* Not a special token */ 485 *p++ = '%'; 486 q--; 487 } 488 q++; 489 } 490 else { 491 *p++ = *q++; 492 } 493 } 494 495 PAM_LOG("Got cache_name: %s", cache_name); 496 497 /* Initialize the new ccache */ 498 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 499 if (krbret != 0) { 500 PAM_LOG_KRB5_ERR(pam_context, krbret, 501 "Error krb5_cc_get_principal()"); 502 retval = PAM_SERVICE_ERR; 503 goto cleanup3; 504 } 505 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 506 if (krbret != 0) { 507 PAM_LOG_KRB5_ERR(pam_context, krbret, "Error krb5_cc_resolve()"); 508 retval = PAM_SERVICE_ERR; 509 goto cleanup2; 510 } 511 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 512 if (krbret != 0) { 513 PAM_LOG_KRB5_ERR(pam_context, krbret, 514 "Error krb5_cc_initialize()"); 515 retval = PAM_SERVICE_ERR; 516 goto cleanup2; 517 } 518 519 PAM_LOG("Cache initialised"); 520 521 /* Prepare for iteration over creds */ 522 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 523 if (krbret != 0) { 524 PAM_LOG_KRB5_ERR(pam_context, krbret, 525 "Error krb5_cc_start_seq_get()"); 526 krb5_cc_destroy(pam_context, ccache_perm); 527 retval = PAM_SERVICE_ERR; 528 goto cleanup2; 529 } 530 531 PAM_LOG("Prepared for iteration"); 532 533 /* Copy the creds (should be two of them) */ 534 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 535 &cursor, &creds) == 0)) { 536 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 537 if (krbret != 0) { 538 PAM_LOG_KRB5_ERR(pam_context, krbret, 539 "Error krb5_cc_store_cred()"); 540 krb5_cc_destroy(pam_context, ccache_perm); 541 krb5_free_cred_contents(pam_context, &creds); 542 retval = PAM_SERVICE_ERR; 543 goto cleanup2; 544 } 545 krb5_free_cred_contents(pam_context, &creds); 546 PAM_LOG("Iteration"); 547 } 548 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 549 550 PAM_LOG("Done iterating"); 551 552 if (strstr(cache_name, "FILE:") == cache_name) { 553 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 554 PAM_LOG("Error chown(): %s", strerror(errno)); 555 krb5_cc_destroy(pam_context, ccache_perm); 556 retval = PAM_SERVICE_ERR; 557 goto cleanup2; 558 } 559 PAM_LOG("Done chown()"); 560 561 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 562 PAM_LOG("Error chmod(): %s", strerror(errno)); 563 krb5_cc_destroy(pam_context, ccache_perm); 564 retval = PAM_SERVICE_ERR; 565 goto cleanup2; 566 } 567 PAM_LOG("Done chmod()"); 568 } 569 570 krb5_cc_close(pam_context, ccache_perm); 571 572 PAM_LOG("Cache closed"); 573 574 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 575 if (retval != PAM_SUCCESS) { 576 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 577 krb5_cc_destroy(pam_context, ccache_perm); 578 retval = PAM_SERVICE_ERR; 579 goto cleanup2; 580 } 581 582 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 583 584cleanup2: 585 krb5_free_principal(pam_context, princ); 586 PAM_LOG("Done cleanup2"); 587cleanup3: 588 krb5_free_context(pam_context); 589 PAM_LOG("Done cleanup3"); 590 591 seteuid(euid); 592 setegid(egid); 593 594 PAM_LOG("Done seteuid() & setegid()"); 595 596 if (cache_name_buf != NULL) 597 free(cache_name_buf); 598 599 return (retval); 600#endif 601} 602 603/* 604 * account management 605 */ 606PAM_EXTERN int 607pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 608 int argc __unused, const char *argv[] __unused) 609{ 610 krb5_error_code krbret; 611 krb5_context pam_context; 612 krb5_ccache ccache; 613 krb5_principal princ; 614 int retval; 615 const void *user; 616 const void *ccache_name; 617 618 retval = pam_get_item(pamh, PAM_USER, &user); 619 if (retval != PAM_SUCCESS) 620 return (retval); 621 622 PAM_LOG("Got user: %s", (const char *)user); 623 624 retval = pam_get_data(pamh, "ccache", &ccache_name); 625 if (retval != PAM_SUCCESS) 626 return (PAM_SUCCESS); 627 628 PAM_LOG("Got credentials"); 629 630 krbret = krb5_init_context(&pam_context); 631 if (krbret != 0) { 632 PAM_LOG("Error krb5_init_context() failed"); 633 return (PAM_PERM_DENIED); 634 } 635 636 PAM_LOG("Context initialised"); 637 638 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 639 if (krbret != 0) { 640 PAM_LOG_KRB5_ERR(pam_context, krbret, 641 "Error krb5_cc_resolve(\"%s\")", (const char *)ccache_name); 642 krb5_free_context(pam_context); 643 return (PAM_PERM_DENIED); 644 } 645 646 PAM_LOG("Got ccache %s", (const char *)ccache_name); 647 648 649 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 650 if (krbret != 0) { 651 PAM_LOG_KRB5_ERR(pam_context, krbret, 652 "Error krb5_cc_get_principal()"); 653 retval = PAM_PERM_DENIED;; 654 goto cleanup; 655 } 656 657 PAM_LOG("Got principal"); 658 659 if (krb5_kuserok(pam_context, princ, (const char *)user)) 660 retval = PAM_SUCCESS; 661 else 662 retval = PAM_PERM_DENIED; 663 krb5_free_principal(pam_context, princ); 664 665 PAM_LOG("Done kuserok()"); 666 667cleanup: 668 krb5_free_context(pam_context); 669 PAM_LOG("Done cleanup"); 670 671 return (retval); 672 673} 674 675/* 676 * password management 677 */ 678PAM_EXTERN int 679pam_sm_chauthtok(pam_handle_t *pamh, int flags, 680 int argc __unused, const char *argv[] __unused) 681{ 682 krb5_error_code krbret; 683 krb5_context pam_context; 684 krb5_creds creds; 685 krb5_principal princ; 686 krb5_get_init_creds_opt *opts; 687 krb5_data result_code_string, result_string; 688 int result_code, retval; 689 const char *pass; 690 const void *user; 691 char *princ_name, *passdup; 692 693 if (!(flags & PAM_UPDATE_AUTHTOK)) 694 return (PAM_AUTHTOK_ERR); 695 696 retval = pam_get_item(pamh, PAM_USER, &user); 697 if (retval != PAM_SUCCESS) 698 return (retval); 699 700 PAM_LOG("Got user: %s", (const char *)user); 701 702 krbret = krb5_init_context(&pam_context); 703 if (krbret != 0) { 704 PAM_LOG("Error krb5_init_context() failed"); 705 return (PAM_SERVICE_ERR); 706 } 707 708 PAM_LOG("Context initialised"); 709 710 /* Get principal name */ 711 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 712 if (krbret != 0) { 713 PAM_LOG_KRB5_ERR(pam_context, krbret, 714 "Error krb5_parse_name()"); 715 retval = PAM_USER_UNKNOWN; 716 goto cleanup3; 717 } 718 719 /* Now convert the principal name into something human readable */ 720 princ_name = NULL; 721 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 722 if (krbret != 0) { 723 PAM_LOG_KRB5_ERR(pam_context, krbret, 724 "Error krb5_unparse_name()"); 725 retval = PAM_SERVICE_ERR; 726 goto cleanup2; 727 } 728 729 PAM_LOG("Got principal: %s", princ_name); 730 731 /* Get password */ 732 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT); 733 if (retval != PAM_SUCCESS) 734 goto cleanup2; 735 736 PAM_LOG("Got password"); 737 738 /* Initialize credentials request options. */ 739 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 740 if (krbret != 0) { 741 PAM_LOG_KRB5_ERR(pam_context, krbret, 742 "Error krb5_get_init_creds_opt_alloc()"); 743 PAM_VERBOSE_ERROR("Kerberos 5 error"); 744 retval = PAM_SERVICE_ERR; 745 goto cleanup2; 746 } 747 748 PAM_LOG("Credentials options initialised"); 749 750 memset(&creds, 0, sizeof(krb5_creds)); 751 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 752 pass, NULL, pamh, 0, "kadmin/changepw", opts); 753 krb5_get_init_creds_opt_free(pam_context, opts); 754 if (krbret != 0) { 755 PAM_LOG_KRB5_ERR(pam_context, krbret, 756 "Error krb5_get_init_creds_password()"); 757 retval = PAM_AUTH_ERR; 758 goto cleanup2; 759 } 760 761 PAM_LOG("Credentials established"); 762 763 /* Now get the new password */ 764 for (;;) { 765 retval = pam_get_authtok(pamh, 766 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 767 if (retval != PAM_TRY_AGAIN) 768 break; 769 pam_error(pamh, "Mismatch; try again, EOF to quit."); 770 } 771 if (retval != PAM_SUCCESS) 772 goto cleanup; 773 774 PAM_LOG("Got new password"); 775 776 /* Change it */ 777 if ((passdup = strdup(pass)) == NULL) { 778 retval = PAM_BUF_ERR; 779 goto cleanup; 780 } 781 krbret = krb5_set_password(pam_context, &creds, passdup, NULL, 782 &result_code, &result_code_string, &result_string); 783 free(passdup); 784 if (krbret != 0) { 785 PAM_LOG_KRB5_ERR(pam_context, krbret, 786 "Error krb5_change_password()"); 787 retval = PAM_AUTHTOK_ERR; 788 goto cleanup; 789 } 790 if (result_code) { 791 PAM_LOG("Error krb5_change_password(): (result_code)"); 792 retval = PAM_AUTHTOK_ERR; 793 goto cleanup; 794 } 795 796 PAM_LOG("Password changed"); 797 798 if (result_string.data) 799 free(result_string.data); 800 if (result_code_string.data) 801 free(result_code_string.data); 802 803cleanup: 804 krb5_free_cred_contents(pam_context, &creds); 805 PAM_LOG("Done cleanup"); 806cleanup2: 807 krb5_free_principal(pam_context, princ); 808 if (princ_name) 809 free(princ_name); 810 PAM_LOG("Done cleanup2"); 811 812cleanup3: 813 krb5_free_context(pam_context); 814 815 PAM_LOG("Done cleanup3"); 816 817 return (retval); 818} 819 820PAM_MODULE_ENTRY("pam_krb5"); 821 822/* 823 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 824 * Modified by Sam Hartman <hartmans@mit.edu> to support PAM services 825 * for Debian. 826 * 827 * Verify the Kerberos ticket-granting ticket just retrieved for the 828 * user. If the Kerberos server doesn't respond, assume the user is 829 * trying to fake us out (since we DID just get a TGT from what is 830 * supposedly our KDC). If the host/<host> service is unknown (i.e., 831 * the local keytab doesn't have it), and we cannot find another 832 * service we do have, let her in. 833 * 834 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 835 */ 836/* ARGSUSED */ 837static int 838verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 839 char *pam_service, int debug) 840{ 841 krb5_error_code retval; 842 krb5_principal princ; 843 krb5_keyblock *keyblock; 844 krb5_data packet; 845 krb5_auth_context auth_context; 846 char phost[BUFSIZ]; 847 const char *services[3], **service; 848 849 packet.data = 0; 850 851 /* If possible we want to try and verify the ticket we have 852 * received against a keytab. We will try multiple service 853 * principals, including at least the host principal and the PAM 854 * service principal. The host principal is preferred because access 855 * to that key is generally sufficient to compromise root, while the 856 * service key for this PAM service may be less carefully guarded. 857 * It is important to check the keytab first before the KDC so we do 858 * not get spoofed by a fake KDC. 859 */ 860 services[0] = "host"; 861 services[1] = pam_service; 862 services[2] = NULL; 863 keyblock = 0; 864 retval = -1; 865 for (service = &services[0]; *service != NULL; service++) { 866 retval = krb5_sname_to_principal(context, NULL, *service, 867 KRB5_NT_SRV_HST, &princ); 868 if (retval != 0) { 869 if (debug) { 870 const char *msg = krb5_get_error_message( 871 context, retval); 872 syslog(LOG_DEBUG, 873 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 874 "krb5_sname_to_principal()", msg); 875 krb5_free_error_message(context, msg); 876 } 877 return -1; 878 } 879 880 /* Extract the name directly. */ 881 strncpy(phost, compat_princ_component(context, princ, 1), 882 BUFSIZ); 883 phost[BUFSIZ - 1] = '\0'; 884 885 /* 886 * Do we have service/<host> keys? 887 * (use default/configured keytab, kvno IGNORE_VNO to get the 888 * first match, and ignore enctype.) 889 */ 890 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 891 &keyblock); 892 if (retval != 0) 893 continue; 894 break; 895 } 896 if (retval != 0) { /* failed to find key */ 897 /* Keytab or service key does not exist */ 898 if (debug) { 899 const char *msg = krb5_get_error_message(context, 900 retval); 901 syslog(LOG_DEBUG, 902 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 903 "krb5_kt_read_service_key()", msg); 904 krb5_free_error_message(context, msg); 905 } 906 retval = 0; 907 goto cleanup; 908 } 909 if (keyblock) 910 krb5_free_keyblock(context, keyblock); 911 912 /* Talk to the kdc and construct the ticket. */ 913 auth_context = NULL; 914 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 915 NULL, ccache, &packet); 916 if (auth_context) { 917 krb5_auth_con_free(context, auth_context); 918 auth_context = NULL; /* setup for rd_req */ 919 } 920 if (retval) { 921 if (debug) { 922 const char *msg = krb5_get_error_message(context, 923 retval); 924 syslog(LOG_DEBUG, 925 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 926 "krb5_mk_req()", msg); 927 krb5_free_error_message(context, msg); 928 } 929 retval = -1; 930 goto cleanup; 931 } 932 933 /* Try to use the ticket. */ 934 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 935 NULL, NULL); 936 if (retval) { 937 if (debug) { 938 const char *msg = krb5_get_error_message(context, 939 retval); 940 syslog(LOG_DEBUG, 941 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 942 "krb5_rd_req()", msg); 943 krb5_free_error_message(context, msg); 944 } 945 retval = -1; 946 } 947 else 948 retval = 1; 949 950cleanup: 951 if (packet.data) 952 compat_free_data_contents(context, &packet); 953 krb5_free_principal(context, princ); 954 return retval; 955} 956 957/* Free the memory for cache_name. Called by pam_end() */ 958/* ARGSUSED */ 959static void 960cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 961{ 962 krb5_context pam_context; 963 krb5_ccache ccache; 964 krb5_error_code krbret; 965 966 if (krb5_init_context(&pam_context)) 967 return; 968 969 krbret = krb5_cc_resolve(pam_context, data, &ccache); 970 if (krbret == 0) 971 krb5_cc_destroy(pam_context, ccache); 972 krb5_free_context(pam_context); 973 free(data); 974} 975 976#ifdef COMPAT_HEIMDAL 977#ifdef COMPAT_MIT 978#error This cannot be MIT and Heimdal compatible! 979#endif 980#endif 981 982#ifndef COMPAT_HEIMDAL 983#ifndef COMPAT_MIT 984#error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 985#endif 986#endif 987 988#ifdef COMPAT_HEIMDAL 989/* ARGSUSED */ 990static const char * 991compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 992{ 993 return princ->name.name_string.val[n]; 994} 995 996/* ARGSUSED */ 997static void 998compat_free_data_contents(krb5_context context __unused, krb5_data * data) 999{ 1000 krb5_xfree(data->data); 1001} 1002#endif 1003 1004#ifdef COMPAT_MIT 1005static const char * 1006compat_princ_component(krb5_context context, krb5_principal princ, int n) 1007{ 1008 return krb5_princ_component(context, princ, n)->data; 1009} 1010 1011static void 1012compat_free_data_contents(krb5_context context, krb5_data * data) 1013{ 1014 krb5_free_data_contents(context, data); 1015} 1016#endif 1017