pam_krb5.c revision 315152
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: stable/10/lib/libpam/modules/pam_krb5/pam_krb5.c 315152 2017-03-12 13:23:23Z des $"); 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 krb5_get_init_creds_opt_set_default_flags(pam_context, 243 service, NULL, opts); 244 245 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 246 krb5_get_init_creds_opt_set_forwardable(opts, 1); 247 248 PAM_LOG("Credential options initialised"); 249 250 /* Get a TGT */ 251 memset(&creds, 0, sizeof(krb5_creds)); 252 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 253 pass, NULL, pamh, 0, NULL, opts); 254 krb5_get_init_creds_opt_free(pam_context, opts); 255 if (krbret != 0) { 256 PAM_VERBOSE_ERROR("Kerberos 5 error"); 257 PAM_LOG_KRB5_ERR(pam_context, krbret, 258 "Error krb5_get_init_creds_password()"); 259 retval = PAM_AUTH_ERR; 260 goto cleanup2; 261 } 262 263 PAM_LOG("Got TGT"); 264 265 /* Generate a temporary cache */ 266 krbret = krb5_cc_new_unique(pam_context, krb5_cc_type_memory, NULL, &ccache); 267 if (krbret != 0) { 268 PAM_VERBOSE_ERROR("Kerberos 5 error"); 269 PAM_LOG_KRB5_ERR(pam_context, krbret, 270 "Error krb5_cc_new_unique()"); 271 retval = PAM_SERVICE_ERR; 272 goto cleanup; 273 } 274 krbret = krb5_cc_initialize(pam_context, ccache, princ); 275 if (krbret != 0) { 276 PAM_VERBOSE_ERROR("Kerberos 5 error"); 277 PAM_LOG_KRB5_ERR(pam_context, krbret, 278 "Error krb5_cc_initialize()"); 279 retval = PAM_SERVICE_ERR; 280 goto cleanup; 281 } 282 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 283 if (krbret != 0) { 284 PAM_VERBOSE_ERROR("Kerberos 5 error"); 285 PAM_LOG_KRB5_ERR(pam_context, krbret, 286 "Error krb5_cc_store_cred()"); 287 krb5_cc_destroy(pam_context, ccache); 288 retval = PAM_SERVICE_ERR; 289 goto cleanup; 290 } 291 292 PAM_LOG("Credentials stashed"); 293 294 /* Verify them */ 295 if ((srvdup = strdup(service)) == NULL) { 296 retval = PAM_BUF_ERR; 297 goto cleanup; 298 } 299 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 300 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 301 free(srvdup); 302 if (krbret == -1) { 303 PAM_VERBOSE_ERROR("Kerberos 5 error"); 304 krb5_cc_destroy(pam_context, ccache); 305 retval = PAM_AUTH_ERR; 306 goto cleanup; 307 } 308 309 PAM_LOG("Credentials stash verified"); 310 311 retval = pam_get_data(pamh, "ccache", &ccache_data); 312 if (retval == PAM_SUCCESS) { 313 krb5_cc_destroy(pam_context, ccache); 314 PAM_VERBOSE_ERROR("Kerberos 5 error"); 315 retval = PAM_AUTH_ERR; 316 goto cleanup; 317 } 318 319 PAM_LOG("Credentials stash not pre-existing"); 320 321 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 322 ccache), krb5_cc_get_name(pam_context, ccache)); 323 if (ccache_name == NULL) { 324 PAM_VERBOSE_ERROR("Kerberos 5 error"); 325 retval = PAM_BUF_ERR; 326 goto cleanup; 327 } 328 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 329 if (retval != 0) { 330 krb5_cc_destroy(pam_context, ccache); 331 PAM_VERBOSE_ERROR("Kerberos 5 error"); 332 retval = PAM_SERVICE_ERR; 333 goto cleanup; 334 } 335 336 PAM_LOG("Credentials stash saved"); 337 338cleanup: 339 krb5_free_cred_contents(pam_context, &creds); 340 PAM_LOG("Done cleanup"); 341cleanup2: 342 krb5_free_principal(pam_context, princ); 343 if (princ_name) 344 free(princ_name); 345 PAM_LOG("Done cleanup2"); 346 347cleanup3: 348 krb5_free_context(pam_context); 349 350 PAM_LOG("Done cleanup3"); 351 352 if (retval != PAM_SUCCESS) 353 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 354 355 return (retval); 356} 357 358PAM_EXTERN int 359pam_sm_setcred(pam_handle_t *pamh, int flags, 360 int argc __unused, const char *argv[] __unused) 361{ 362#ifdef _FREEFALL_CONFIG 363 return (PAM_SUCCESS); 364#else 365 366 krb5_error_code krbret; 367 krb5_context pam_context; 368 krb5_principal princ; 369 krb5_creds creds; 370 krb5_ccache ccache_temp, ccache_perm; 371 krb5_cc_cursor cursor; 372 struct passwd *pwd = NULL; 373 int retval; 374 const char *cache_name, *q; 375 const void *user; 376 const void *cache_data; 377 char *cache_name_buf = NULL, *p; 378 379 uid_t euid; 380 gid_t egid; 381 382 if (flags & PAM_DELETE_CRED) 383 return (PAM_SUCCESS); 384 385 if (flags & PAM_REFRESH_CRED) 386 return (PAM_SUCCESS); 387 388 if (flags & PAM_REINITIALIZE_CRED) 389 return (PAM_SUCCESS); 390 391 if (!(flags & PAM_ESTABLISH_CRED)) 392 return (PAM_SERVICE_ERR); 393 394 /* If a persistent cache isn't desired, stop now. */ 395 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE) || 396 openpam_get_option(pamh, PAM_OPT_NO_USER_CHECK)) 397 return (PAM_SUCCESS); 398 399 PAM_LOG("Establishing credentials"); 400 401 /* Get username */ 402 retval = pam_get_item(pamh, PAM_USER, &user); 403 if (retval != PAM_SUCCESS) 404 return (retval); 405 406 PAM_LOG("Got user: %s", (const char *)user); 407 408 krbret = krb5_init_context(&pam_context); 409 if (krbret != 0) { 410 PAM_LOG("Error krb5_init_context() failed"); 411 return (PAM_SERVICE_ERR); 412 } 413 414 PAM_LOG("Context initialised"); 415 416 euid = geteuid(); /* Usually 0 */ 417 egid = getegid(); 418 419 PAM_LOG("Got euid, egid: %d %d", euid, egid); 420 421 /* Retrieve the temporary cache */ 422 retval = pam_get_data(pamh, "ccache", &cache_data); 423 if (retval != PAM_SUCCESS) { 424 retval = PAM_CRED_UNAVAIL; 425 goto cleanup3; 426 } 427 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 428 if (krbret != 0) { 429 PAM_LOG_KRB5_ERR(pam_context, krbret, 430 "Error krb5_cc_resolve(\"%s\")", (const char *)cache_data); 431 retval = PAM_SERVICE_ERR; 432 goto cleanup3; 433 } 434 435 /* Get the uid. This should exist. */ 436 pwd = getpwnam(user); 437 if (pwd == NULL) { 438 retval = PAM_USER_UNKNOWN; 439 goto cleanup3; 440 } 441 442 PAM_LOG("Done getpwnam()"); 443 444 /* Avoid following a symlink as root */ 445 if (setegid(pwd->pw_gid)) { 446 retval = PAM_SERVICE_ERR; 447 goto cleanup3; 448 } 449 if (seteuid(pwd->pw_uid)) { 450 retval = PAM_SERVICE_ERR; 451 goto cleanup3; 452 } 453 454 PAM_LOG("Done setegid() & seteuid()"); 455 456 /* Get the cache name */ 457 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 458 if (cache_name == NULL) { 459 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 460 cache_name = cache_name_buf; 461 } 462 463 p = calloc(PATH_MAX + 16, sizeof(char)); 464 q = cache_name; 465 466 if (p == NULL) { 467 PAM_LOG("Error malloc(): failure"); 468 retval = PAM_BUF_ERR; 469 goto cleanup3; 470 } 471 cache_name = p; 472 473 /* convert %u and %p */ 474 while (*q) { 475 if (*q == '%') { 476 q++; 477 if (*q == 'u') { 478 sprintf(p, "%d", pwd->pw_uid); 479 p += strlen(p); 480 } 481 else if (*q == 'p') { 482 sprintf(p, "%d", getpid()); 483 p += strlen(p); 484 } 485 else { 486 /* Not a special token */ 487 *p++ = '%'; 488 q--; 489 } 490 q++; 491 } 492 else { 493 *p++ = *q++; 494 } 495 } 496 497 PAM_LOG("Got cache_name: %s", cache_name); 498 499 /* Initialize the new ccache */ 500 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 501 if (krbret != 0) { 502 PAM_LOG_KRB5_ERR(pam_context, krbret, 503 "Error krb5_cc_get_principal()"); 504 retval = PAM_SERVICE_ERR; 505 goto cleanup3; 506 } 507 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 508 if (krbret != 0) { 509 PAM_LOG_KRB5_ERR(pam_context, krbret, "Error krb5_cc_resolve()"); 510 retval = PAM_SERVICE_ERR; 511 goto cleanup2; 512 } 513 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 514 if (krbret != 0) { 515 PAM_LOG_KRB5_ERR(pam_context, krbret, 516 "Error krb5_cc_initialize()"); 517 retval = PAM_SERVICE_ERR; 518 goto cleanup2; 519 } 520 521 PAM_LOG("Cache initialised"); 522 523 /* Prepare for iteration over creds */ 524 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 525 if (krbret != 0) { 526 PAM_LOG_KRB5_ERR(pam_context, krbret, 527 "Error krb5_cc_start_seq_get()"); 528 krb5_cc_destroy(pam_context, ccache_perm); 529 retval = PAM_SERVICE_ERR; 530 goto cleanup2; 531 } 532 533 PAM_LOG("Prepared for iteration"); 534 535 /* Copy the creds (should be two of them) */ 536 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 537 &cursor, &creds) == 0)) { 538 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 539 if (krbret != 0) { 540 PAM_LOG_KRB5_ERR(pam_context, krbret, 541 "Error krb5_cc_store_cred()"); 542 krb5_cc_destroy(pam_context, ccache_perm); 543 krb5_free_cred_contents(pam_context, &creds); 544 retval = PAM_SERVICE_ERR; 545 goto cleanup2; 546 } 547 krb5_free_cred_contents(pam_context, &creds); 548 PAM_LOG("Iteration"); 549 } 550 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 551 552 PAM_LOG("Done iterating"); 553 554 if (strstr(cache_name, "FILE:") == cache_name) { 555 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 556 PAM_LOG("Error chown(): %s", strerror(errno)); 557 krb5_cc_destroy(pam_context, ccache_perm); 558 retval = PAM_SERVICE_ERR; 559 goto cleanup2; 560 } 561 PAM_LOG("Done chown()"); 562 563 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 564 PAM_LOG("Error chmod(): %s", strerror(errno)); 565 krb5_cc_destroy(pam_context, ccache_perm); 566 retval = PAM_SERVICE_ERR; 567 goto cleanup2; 568 } 569 PAM_LOG("Done chmod()"); 570 } 571 572 krb5_cc_close(pam_context, ccache_perm); 573 574 PAM_LOG("Cache closed"); 575 576 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 577 if (retval != PAM_SUCCESS) { 578 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 579 krb5_cc_destroy(pam_context, ccache_perm); 580 retval = PAM_SERVICE_ERR; 581 goto cleanup2; 582 } 583 584 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 585 586cleanup2: 587 krb5_free_principal(pam_context, princ); 588 PAM_LOG("Done cleanup2"); 589cleanup3: 590 krb5_free_context(pam_context); 591 PAM_LOG("Done cleanup3"); 592 593 seteuid(euid); 594 setegid(egid); 595 596 PAM_LOG("Done seteuid() & setegid()"); 597 598 if (cache_name_buf != NULL) 599 free(cache_name_buf); 600 601 return (retval); 602#endif 603} 604 605/* 606 * account management 607 */ 608PAM_EXTERN int 609pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 610 int argc __unused, const char *argv[] __unused) 611{ 612 krb5_error_code krbret; 613 krb5_context pam_context; 614 krb5_ccache ccache; 615 krb5_principal princ; 616 int retval; 617 const void *user; 618 const void *ccache_name; 619 620 retval = pam_get_item(pamh, PAM_USER, &user); 621 if (retval != PAM_SUCCESS) 622 return (retval); 623 624 PAM_LOG("Got user: %s", (const char *)user); 625 626 retval = pam_get_data(pamh, "ccache", &ccache_name); 627 if (retval != PAM_SUCCESS) 628 return (PAM_SUCCESS); 629 630 PAM_LOG("Got credentials"); 631 632 krbret = krb5_init_context(&pam_context); 633 if (krbret != 0) { 634 PAM_LOG("Error krb5_init_context() failed"); 635 return (PAM_PERM_DENIED); 636 } 637 638 PAM_LOG("Context initialised"); 639 640 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 641 if (krbret != 0) { 642 PAM_LOG_KRB5_ERR(pam_context, krbret, 643 "Error krb5_cc_resolve(\"%s\")", (const char *)ccache_name); 644 krb5_free_context(pam_context); 645 return (PAM_PERM_DENIED); 646 } 647 648 PAM_LOG("Got ccache %s", (const char *)ccache_name); 649 650 651 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 652 if (krbret != 0) { 653 PAM_LOG_KRB5_ERR(pam_context, krbret, 654 "Error krb5_cc_get_principal()"); 655 retval = PAM_PERM_DENIED; 656 goto cleanup; 657 } 658 659 PAM_LOG("Got principal"); 660 661 if (krb5_kuserok(pam_context, princ, (const char *)user)) 662 retval = PAM_SUCCESS; 663 else 664 retval = PAM_PERM_DENIED; 665 krb5_free_principal(pam_context, princ); 666 667 PAM_LOG("Done kuserok()"); 668 669cleanup: 670 krb5_free_context(pam_context); 671 PAM_LOG("Done cleanup"); 672 673 return (retval); 674 675} 676 677/* 678 * password management 679 */ 680PAM_EXTERN int 681pam_sm_chauthtok(pam_handle_t *pamh, int flags, 682 int argc __unused, const char *argv[] __unused) 683{ 684 krb5_error_code krbret; 685 krb5_context pam_context; 686 krb5_creds creds; 687 krb5_principal princ; 688 krb5_get_init_creds_opt *opts; 689 krb5_data result_code_string, result_string; 690 int result_code, retval; 691 const char *pass; 692 const void *user; 693 char *princ_name, *passdup; 694 695 if (!(flags & PAM_UPDATE_AUTHTOK)) 696 return (PAM_AUTHTOK_ERR); 697 698 retval = pam_get_item(pamh, PAM_USER, &user); 699 if (retval != PAM_SUCCESS) 700 return (retval); 701 702 PAM_LOG("Got user: %s", (const char *)user); 703 704 krbret = krb5_init_context(&pam_context); 705 if (krbret != 0) { 706 PAM_LOG("Error krb5_init_context() failed"); 707 return (PAM_SERVICE_ERR); 708 } 709 710 PAM_LOG("Context initialised"); 711 712 /* Get principal name */ 713 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 714 if (krbret != 0) { 715 PAM_LOG_KRB5_ERR(pam_context, krbret, 716 "Error krb5_parse_name()"); 717 retval = PAM_USER_UNKNOWN; 718 goto cleanup3; 719 } 720 721 /* Now convert the principal name into something human readable */ 722 princ_name = NULL; 723 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 724 if (krbret != 0) { 725 PAM_LOG_KRB5_ERR(pam_context, krbret, 726 "Error krb5_unparse_name()"); 727 retval = PAM_SERVICE_ERR; 728 goto cleanup2; 729 } 730 731 PAM_LOG("Got principal: %s", princ_name); 732 733 /* Get password */ 734 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, PASSWORD_PROMPT); 735 if (retval != PAM_SUCCESS) 736 goto cleanup2; 737 738 PAM_LOG("Got password"); 739 740 /* Initialize credentials request options. */ 741 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 742 if (krbret != 0) { 743 PAM_LOG_KRB5_ERR(pam_context, krbret, 744 "Error krb5_get_init_creds_opt_alloc()"); 745 PAM_VERBOSE_ERROR("Kerberos 5 error"); 746 retval = PAM_SERVICE_ERR; 747 goto cleanup2; 748 } 749 750 PAM_LOG("Credentials options initialised"); 751 752 memset(&creds, 0, sizeof(krb5_creds)); 753 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 754 pass, NULL, pamh, 0, "kadmin/changepw", opts); 755 krb5_get_init_creds_opt_free(pam_context, opts); 756 if (krbret != 0) { 757 PAM_LOG_KRB5_ERR(pam_context, krbret, 758 "Error krb5_get_init_creds_password()"); 759 retval = PAM_AUTH_ERR; 760 goto cleanup2; 761 } 762 763 PAM_LOG("Credentials established"); 764 765 /* Now get the new password */ 766 for (;;) { 767 retval = pam_get_authtok(pamh, 768 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 769 if (retval != PAM_TRY_AGAIN) 770 break; 771 pam_error(pamh, "Mismatch; try again, EOF to quit."); 772 } 773 if (retval != PAM_SUCCESS) 774 goto cleanup; 775 776 PAM_LOG("Got new password"); 777 778 /* Change it */ 779 if ((passdup = strdup(pass)) == NULL) { 780 retval = PAM_BUF_ERR; 781 goto cleanup; 782 } 783 krbret = krb5_set_password(pam_context, &creds, passdup, NULL, 784 &result_code, &result_code_string, &result_string); 785 free(passdup); 786 if (krbret != 0) { 787 PAM_LOG_KRB5_ERR(pam_context, krbret, 788 "Error krb5_change_password()"); 789 retval = PAM_AUTHTOK_ERR; 790 goto cleanup; 791 } 792 if (result_code) { 793 PAM_LOG("Error krb5_change_password(): (result_code)"); 794 retval = PAM_AUTHTOK_ERR; 795 goto cleanup; 796 } 797 798 PAM_LOG("Password changed"); 799 800 if (result_string.data) 801 free(result_string.data); 802 if (result_code_string.data) 803 free(result_code_string.data); 804 805cleanup: 806 krb5_free_cred_contents(pam_context, &creds); 807 PAM_LOG("Done cleanup"); 808cleanup2: 809 krb5_free_principal(pam_context, princ); 810 if (princ_name) 811 free(princ_name); 812 PAM_LOG("Done cleanup2"); 813 814cleanup3: 815 krb5_free_context(pam_context); 816 817 PAM_LOG("Done cleanup3"); 818 819 return (retval); 820} 821 822PAM_MODULE_ENTRY("pam_krb5"); 823 824/* 825 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 826 * Modified by Sam Hartman <hartmans@mit.edu> to support PAM services 827 * for Debian. 828 * 829 * Verify the Kerberos ticket-granting ticket just retrieved for the 830 * user. If the Kerberos server doesn't respond, assume the user is 831 * trying to fake us out (since we DID just get a TGT from what is 832 * supposedly our KDC). If the host/<host> service is unknown (i.e., 833 * the local keytab doesn't have it), and we cannot find another 834 * service we do have, let her in. 835 * 836 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 837 */ 838/* ARGSUSED */ 839static int 840verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 841 char *pam_service, int debug) 842{ 843 krb5_error_code retval; 844 krb5_principal princ; 845 krb5_keyblock *keyblock; 846 krb5_data packet; 847 krb5_auth_context auth_context; 848 char phost[BUFSIZ]; 849 const char *services[3], **service; 850 851 packet.data = 0; 852 853 /* If possible we want to try and verify the ticket we have 854 * received against a keytab. We will try multiple service 855 * principals, including at least the host principal and the PAM 856 * service principal. The host principal is preferred because access 857 * to that key is generally sufficient to compromise root, while the 858 * service key for this PAM service may be less carefully guarded. 859 * It is important to check the keytab first before the KDC so we do 860 * not get spoofed by a fake KDC. 861 */ 862 services[0] = "host"; 863 services[1] = pam_service; 864 services[2] = NULL; 865 keyblock = 0; 866 retval = -1; 867 for (service = &services[0]; *service != NULL; service++) { 868 retval = krb5_sname_to_principal(context, NULL, *service, 869 KRB5_NT_SRV_HST, &princ); 870 if (retval != 0) { 871 if (debug) { 872 const char *msg = krb5_get_error_message( 873 context, retval); 874 syslog(LOG_DEBUG, 875 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 876 "krb5_sname_to_principal()", msg); 877 krb5_free_error_message(context, msg); 878 } 879 return -1; 880 } 881 882 /* Extract the name directly. */ 883 strncpy(phost, compat_princ_component(context, princ, 1), 884 BUFSIZ); 885 phost[BUFSIZ - 1] = '\0'; 886 887 /* 888 * Do we have service/<host> keys? 889 * (use default/configured keytab, kvno IGNORE_VNO to get the 890 * first match, and ignore enctype.) 891 */ 892 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 893 &keyblock); 894 if (retval != 0) 895 continue; 896 break; 897 } 898 if (retval != 0) { /* failed to find key */ 899 /* Keytab or service key does not exist */ 900 if (debug) { 901 const char *msg = krb5_get_error_message(context, 902 retval); 903 syslog(LOG_DEBUG, 904 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 905 "krb5_kt_read_service_key()", msg); 906 krb5_free_error_message(context, msg); 907 } 908 retval = 0; 909 goto cleanup; 910 } 911 if (keyblock) 912 krb5_free_keyblock(context, keyblock); 913 914 /* Talk to the kdc and construct the ticket. */ 915 auth_context = NULL; 916 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 917 NULL, ccache, &packet); 918 if (auth_context) { 919 krb5_auth_con_free(context, auth_context); 920 auth_context = NULL; /* setup for rd_req */ 921 } 922 if (retval) { 923 if (debug) { 924 const char *msg = krb5_get_error_message(context, 925 retval); 926 syslog(LOG_DEBUG, 927 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 928 "krb5_mk_req()", msg); 929 krb5_free_error_message(context, msg); 930 } 931 retval = -1; 932 goto cleanup; 933 } 934 935 /* Try to use the ticket. */ 936 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 937 NULL, NULL); 938 if (retval) { 939 if (debug) { 940 const char *msg = krb5_get_error_message(context, 941 retval); 942 syslog(LOG_DEBUG, 943 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 944 "krb5_rd_req()", msg); 945 krb5_free_error_message(context, msg); 946 } 947 retval = -1; 948 } 949 else 950 retval = 1; 951 952cleanup: 953 if (packet.data) 954 compat_free_data_contents(context, &packet); 955 krb5_free_principal(context, princ); 956 return retval; 957} 958 959/* Free the memory for cache_name. Called by pam_end() */ 960/* ARGSUSED */ 961static void 962cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 963{ 964 krb5_context pam_context; 965 krb5_ccache ccache; 966 krb5_error_code krbret; 967 968 if (krb5_init_context(&pam_context)) 969 return; 970 971 krbret = krb5_cc_resolve(pam_context, data, &ccache); 972 if (krbret == 0) 973 krb5_cc_destroy(pam_context, ccache); 974 krb5_free_context(pam_context); 975 free(data); 976} 977 978#ifdef COMPAT_HEIMDAL 979#ifdef COMPAT_MIT 980#error This cannot be MIT and Heimdal compatible! 981#endif 982#endif 983 984#ifndef COMPAT_HEIMDAL 985#ifndef COMPAT_MIT 986#error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 987#endif 988#endif 989 990#ifdef COMPAT_HEIMDAL 991/* ARGSUSED */ 992static const char * 993compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 994{ 995 return princ->name.name_string.val[n]; 996} 997 998/* ARGSUSED */ 999static void 1000compat_free_data_contents(krb5_context context __unused, krb5_data * data) 1001{ 1002 krb5_xfree(data->data); 1003} 1004#endif 1005 1006#ifdef COMPAT_MIT 1007static const char * 1008compat_princ_component(krb5_context context, krb5_principal princ, int n) 1009{ 1010 return krb5_princ_component(context, princ, n)->data; 1011} 1012 1013static void 1014compat_free_data_contents(krb5_context context, krb5_data * data) 1015{ 1016 krb5_free_data_contents(context, data); 1017} 1018#endif 1019