pam_krb5.c revision 1.9
1 /* $NetBSD: pam_krb5.c,v 1.9 2005/04/19 03:38:47 lukem 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 1.9 2005/04/19 03:38:47 lukem 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, pwres; 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 char pwbuf[1024]; 121 122 retval = pam_get_user(pamh, &user, USER_PROMPT); 123 if (retval != PAM_SUCCESS) 124 return (retval); 125 126 PAM_LOG("Got user: %s", user); 127 128 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 129 if (retval != PAM_SUCCESS) 130 return (retval); 131 132 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 133 134 service = NULL; 135 pam_get_item(pamh, PAM_SERVICE, &service); 136 if (service == NULL) 137 service = "unknown"; 138 139 PAM_LOG("Got service: %s", (const char *)service); 140 141 krbret = krb5_init_context(&pam_context); 142 if (krbret != 0) { 143 PAM_VERBOSE_ERROR("Kerberos 5 error"); 144 return (PAM_SERVICE_ERR); 145 } 146 147 PAM_LOG("Context initialised"); 148 149 krb5_get_init_creds_opt_init(&opts); 150 151 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 152 krb5_get_init_creds_opt_set_forwardable(&opts, 1); 153 154 PAM_LOG("Credentials initialised"); 155 156 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 157 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 158 PAM_VERBOSE_ERROR("Kerberos 5 error"); 159 retval = PAM_SERVICE_ERR; 160 goto cleanup3; 161 } 162 163 PAM_LOG("Done krb5_cc_register()"); 164 165 /* Get principal name */ 166 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 167 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 168 else 169 principal = strdup(user); 170 171 PAM_LOG("Created principal: %s", principal); 172 173 krbret = krb5_parse_name(pam_context, principal, &princ); 174 free(principal); 175 if (krbret != 0) { 176 PAM_LOG("Error krb5_parse_name(): %s", 177 krb5_get_err_text(pam_context, krbret)); 178 PAM_VERBOSE_ERROR("Kerberos 5 error"); 179 retval = PAM_SERVICE_ERR; 180 goto cleanup3; 181 } 182 183 PAM_LOG("Done krb5_parse_name()"); 184 185 /* Now convert the principal name into something human readable */ 186 princ_name = NULL; 187 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 188 if (krbret != 0) { 189 PAM_LOG("Error krb5_unparse_name(): %s", 190 krb5_get_err_text(pam_context, krbret)); 191 PAM_VERBOSE_ERROR("Kerberos 5 error"); 192 retval = PAM_SERVICE_ERR; 193 goto cleanup2; 194 } 195 196 PAM_LOG("Got principal: %s", princ_name); 197 198 /* Get password */ 199 (void) snprintf(password_prompt, sizeof(password_prompt), 200 PASSWORD_PROMPT, princ_name); 201 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, password_prompt); 202 if (retval != PAM_SUCCESS) 203 goto cleanup2; 204 205 PAM_LOG("Got password"); 206 207 /* Verify the local user exists (AFTER getting the password) */ 208 if (strchr(user, '@')) { 209 /* get a local account name for this principal */ 210 krbret = krb5_aname_to_localname(pam_context, princ, 211 sizeof(luser), luser); 212 if (krbret != 0) { 213 PAM_VERBOSE_ERROR("Kerberos 5 error"); 214 PAM_LOG("Error krb5_aname_to_localname(): %s", 215 krb5_get_err_text(pam_context, krbret)); 216 retval = PAM_USER_UNKNOWN; 217 goto cleanup2; 218 } 219 220 retval = pam_set_item(pamh, PAM_USER, luser); 221 if (retval != PAM_SUCCESS) 222 goto cleanup2; 223 224 PAM_LOG("PAM_USER Redone"); 225 } 226 227 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 228 pwd == NULL) { 229 retval = PAM_USER_UNKNOWN; 230 goto cleanup2; 231 } 232 233 PAM_LOG("Done getpwnam_r()"); 234 235 /* Get a TGT */ 236 memset(&creds, 0, sizeof(krb5_creds)); 237 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 238 pass, NULL, pamh, 0, NULL, &opts); 239 if (krbret != 0) { 240 PAM_VERBOSE_ERROR("Kerberos 5 error"); 241 PAM_LOG("Error krb5_get_init_creds_password(): %s", 242 krb5_get_err_text(pam_context, krbret)); 243 retval = PAM_AUTH_ERR; 244 goto cleanup2; 245 } 246 247 PAM_LOG("Got TGT"); 248 249 /* Generate a temporary cache */ 250 krbret = krb5_cc_gen_new(pam_context, &krb5_mcc_ops, &ccache); 251 if (krbret != 0) { 252 PAM_VERBOSE_ERROR("Kerberos 5 error"); 253 PAM_LOG("Error krb5_cc_gen_new(): %s", 254 krb5_get_err_text(pam_context, krbret)); 255 retval = PAM_SERVICE_ERR; 256 goto cleanup; 257 } 258 krbret = krb5_cc_initialize(pam_context, ccache, princ); 259 if (krbret != 0) { 260 PAM_VERBOSE_ERROR("Kerberos 5 error"); 261 PAM_LOG("Error krb5_cc_initialize(): %s", 262 krb5_get_err_text(pam_context, krbret)); 263 retval = PAM_SERVICE_ERR; 264 goto cleanup; 265 } 266 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 267 if (krbret != 0) { 268 PAM_VERBOSE_ERROR("Kerberos 5 error"); 269 PAM_LOG("Error krb5_cc_store_cred(): %s", 270 krb5_get_err_text(pam_context, krbret)); 271 krb5_cc_destroy(pam_context, ccache); 272 retval = PAM_SERVICE_ERR; 273 goto cleanup; 274 } 275 276 PAM_LOG("Credentials stashed"); 277 278 /* Verify them */ 279 if ((srvdup = strdup(service)) == NULL) { 280 retval = PAM_BUF_ERR; 281 goto cleanup; 282 } 283 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 284 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 285 free(srvdup); 286 if (krbret == -1) { 287 PAM_VERBOSE_ERROR("Kerberos 5 error"); 288 krb5_cc_destroy(pam_context, ccache); 289 retval = PAM_AUTH_ERR; 290 goto cleanup; 291 } 292 293 PAM_LOG("Credentials stash verified"); 294 295 retval = pam_get_data(pamh, "ccache", &ccache_data); 296 if (retval == PAM_SUCCESS) { 297 krb5_cc_destroy(pam_context, ccache); 298 PAM_VERBOSE_ERROR("Kerberos 5 error"); 299 retval = PAM_AUTH_ERR; 300 goto cleanup; 301 } 302 303 PAM_LOG("Credentials stash not pre-existing"); 304 305 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 306 ccache), krb5_cc_get_name(pam_context, ccache)); 307 if (ccache_name == NULL) { 308 PAM_VERBOSE_ERROR("Kerberos 5 error"); 309 retval = PAM_BUF_ERR; 310 goto cleanup; 311 } 312 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 313 if (retval != 0) { 314 krb5_cc_destroy(pam_context, ccache); 315 PAM_VERBOSE_ERROR("Kerberos 5 error"); 316 retval = PAM_SERVICE_ERR; 317 goto cleanup; 318 } 319 320 PAM_LOG("Credentials stash saved"); 321 322 cleanup: 323 krb5_free_cred_contents(pam_context, &creds); 324 PAM_LOG("Done cleanup"); 325 cleanup2: 326 krb5_free_principal(pam_context, princ); 327 PAM_LOG("Done cleanup2"); 328 cleanup3: 329 if (princ_name) 330 free(princ_name); 331 332 krb5_free_context(pam_context); 333 334 PAM_LOG("Done cleanup3"); 335 336 if (retval != PAM_SUCCESS) 337 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 338 339 return (retval); 340 } 341 342 PAM_EXTERN int 343 pam_sm_setcred(pam_handle_t *pamh, int flags, 344 int argc __unused, const char *argv[] __unused) 345 { 346 347 krb5_error_code krbret; 348 krb5_context pam_context; 349 krb5_principal princ; 350 krb5_creds creds; 351 krb5_ccache ccache_temp, ccache_perm; 352 krb5_cc_cursor cursor; 353 struct passwd *pwd = NULL, pwres; 354 int retval; 355 const char *cache_name, *q; 356 const void *user; 357 void *cache_data; 358 char *cache_name_buf = NULL, *p; 359 char pwbuf[1024]; 360 361 uid_t euid; 362 gid_t egid; 363 364 if (flags & PAM_DELETE_CRED) 365 return (PAM_SUCCESS); 366 367 if (flags & PAM_REFRESH_CRED) 368 return (PAM_SUCCESS); 369 370 if (flags & PAM_REINITIALIZE_CRED) 371 return (PAM_SUCCESS); 372 373 if (!(flags & PAM_ESTABLISH_CRED)) 374 return (PAM_SERVICE_ERR); 375 376 /* If a persistent cache isn't desired, stop now. */ 377 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE)) 378 return (PAM_SUCCESS); 379 380 PAM_LOG("Establishing credentials"); 381 382 /* Get username */ 383 retval = pam_get_item(pamh, PAM_USER, &user); 384 if (retval != PAM_SUCCESS) 385 return (retval); 386 387 PAM_LOG("Got user: %s", (const char *)user); 388 389 krbret = krb5_init_context(&pam_context); 390 if (krbret != 0) { 391 PAM_LOG("Error krb5_init_context() failed"); 392 return (PAM_SERVICE_ERR); 393 } 394 395 PAM_LOG("Context initialised"); 396 397 euid = geteuid(); /* Usually 0 */ 398 egid = getegid(); 399 400 PAM_LOG("Got euid, egid: %d %d", euid, egid); 401 402 /* Retrieve the temporary cache */ 403 retval = pam_get_data(pamh, "ccache", &cache_data); 404 if (retval != PAM_SUCCESS) { 405 retval = PAM_CRED_UNAVAIL; 406 goto cleanup3; 407 } 408 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 409 if (krbret != 0) { 410 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 411 krb5_get_err_text(pam_context, krbret)); 412 retval = PAM_SERVICE_ERR; 413 goto cleanup3; 414 } 415 416 /* Get the uid. This should exist. */ 417 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 418 pwd == NULL) { 419 retval = PAM_USER_UNKNOWN; 420 goto cleanup3; 421 } 422 423 PAM_LOG("Done getpwnam_r()"); 424 425 /* Avoid following a symlink as root */ 426 if (setegid(pwd->pw_gid)) { 427 retval = PAM_SERVICE_ERR; 428 goto cleanup3; 429 } 430 if (seteuid(pwd->pw_uid)) { 431 retval = PAM_SERVICE_ERR; 432 goto cleanup3; 433 } 434 435 PAM_LOG("Done setegid() & seteuid()"); 436 437 /* Get the cache name */ 438 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 439 if (cache_name == NULL) { 440 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 441 cache_name = cache_name_buf; 442 } 443 444 p = calloc(PATH_MAX + 16, sizeof(char)); 445 q = cache_name; 446 447 if (p == NULL) { 448 PAM_LOG("Error malloc(): failure"); 449 retval = PAM_BUF_ERR; 450 goto cleanup3; 451 } 452 cache_name = p; 453 454 /* convert %u and %p */ 455 while (*q) { 456 if (*q == '%') { 457 q++; 458 if (*q == 'u') { 459 sprintf(p, "%d", pwd->pw_uid); 460 p += strlen(p); 461 } 462 else if (*q == 'p') { 463 sprintf(p, "%d", getpid()); 464 p += strlen(p); 465 } 466 else { 467 /* Not a special token */ 468 *p++ = '%'; 469 q--; 470 } 471 q++; 472 } 473 else { 474 *p++ = *q++; 475 } 476 } 477 478 PAM_LOG("Got cache_name: %s", cache_name); 479 480 /* Initialize the new ccache */ 481 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 482 if (krbret != 0) { 483 PAM_LOG("Error krb5_cc_get_principal(): %s", 484 krb5_get_err_text(pam_context, krbret)); 485 retval = PAM_SERVICE_ERR; 486 goto cleanup3; 487 } 488 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 489 if (krbret != 0) { 490 PAM_LOG("Error krb5_cc_resolve(): %s", 491 krb5_get_err_text(pam_context, krbret)); 492 retval = PAM_SERVICE_ERR; 493 goto cleanup2; 494 } 495 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 496 if (krbret != 0) { 497 PAM_LOG("Error krb5_cc_initialize(): %s", 498 krb5_get_err_text(pam_context, krbret)); 499 retval = PAM_SERVICE_ERR; 500 goto cleanup2; 501 } 502 503 PAM_LOG("Cache initialised"); 504 505 /* Prepare for iteration over creds */ 506 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 507 if (krbret != 0) { 508 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 509 krb5_get_err_text(pam_context, krbret)); 510 krb5_cc_destroy(pam_context, ccache_perm); 511 retval = PAM_SERVICE_ERR; 512 goto cleanup2; 513 } 514 515 PAM_LOG("Prepared for iteration"); 516 517 /* Copy the creds (should be two of them) */ 518 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 519 &cursor, &creds) == 0)) { 520 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 521 if (krbret != 0) { 522 PAM_LOG("Error krb5_cc_store_cred(): %s", 523 krb5_get_err_text(pam_context, krbret)); 524 krb5_cc_destroy(pam_context, ccache_perm); 525 krb5_free_cred_contents(pam_context, &creds); 526 retval = PAM_SERVICE_ERR; 527 goto cleanup2; 528 } 529 krb5_free_cred_contents(pam_context, &creds); 530 PAM_LOG("Iteration"); 531 } 532 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 533 534 PAM_LOG("Done iterating"); 535 536 if (strstr(cache_name, "FILE:") == cache_name) { 537 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 538 PAM_LOG("Error chown(): %s", strerror(errno)); 539 krb5_cc_destroy(pam_context, ccache_perm); 540 retval = PAM_SERVICE_ERR; 541 goto cleanup2; 542 } 543 PAM_LOG("Done chown()"); 544 545 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 546 PAM_LOG("Error chmod(): %s", strerror(errno)); 547 krb5_cc_destroy(pam_context, ccache_perm); 548 retval = PAM_SERVICE_ERR; 549 goto cleanup2; 550 } 551 PAM_LOG("Done chmod()"); 552 } 553 554 krb5_cc_close(pam_context, ccache_perm); 555 556 PAM_LOG("Cache closed"); 557 558 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 559 if (retval != PAM_SUCCESS) { 560 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 561 krb5_cc_destroy(pam_context, ccache_perm); 562 retval = PAM_SERVICE_ERR; 563 goto cleanup2; 564 } 565 566 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 567 568 cleanup2: 569 krb5_free_principal(pam_context, princ); 570 PAM_LOG("Done cleanup2"); 571 cleanup3: 572 krb5_free_context(pam_context); 573 PAM_LOG("Done cleanup3"); 574 575 seteuid(euid); 576 setegid(egid); 577 578 PAM_LOG("Done seteuid() & setegid()"); 579 580 if (cache_name_buf != NULL) 581 free(cache_name_buf); 582 583 return (retval); 584 } 585 586 /* 587 * account management 588 */ 589 PAM_EXTERN int 590 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 591 int argc __unused, const char *argv[] __unused) 592 { 593 krb5_error_code krbret; 594 krb5_context pam_context; 595 krb5_ccache ccache; 596 krb5_principal princ; 597 int retval; 598 const void *user; 599 void *ccache_name; 600 601 retval = pam_get_item(pamh, PAM_USER, &user); 602 if (retval != PAM_SUCCESS) 603 return (retval); 604 605 PAM_LOG("Got user: %s", (const char *)user); 606 607 retval = pam_get_data(pamh, "ccache", &ccache_name); 608 if (retval != PAM_SUCCESS) 609 return (PAM_SUCCESS); 610 611 PAM_LOG("Got credentials"); 612 613 krbret = krb5_init_context(&pam_context); 614 if (krbret != 0) { 615 PAM_LOG("Error krb5_init_context() failed"); 616 return (PAM_PERM_DENIED); 617 } 618 619 PAM_LOG("Context initialised"); 620 621 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 622 if (krbret != 0) { 623 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 624 krb5_get_err_text(pam_context, krbret)); 625 krb5_free_context(pam_context); 626 return (PAM_PERM_DENIED); 627 } 628 629 PAM_LOG("Got ccache %s", (const char *)ccache_name); 630 631 632 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 633 if (krbret != 0) { 634 PAM_LOG("Error krb5_cc_get_principal(): %s", 635 krb5_get_err_text(pam_context, krbret)); 636 retval = PAM_PERM_DENIED;; 637 goto cleanup; 638 } 639 640 PAM_LOG("Got principal"); 641 642 if (krb5_kuserok(pam_context, princ, (const char *)user)) 643 retval = PAM_SUCCESS; 644 else 645 retval = PAM_PERM_DENIED; 646 krb5_free_principal(pam_context, princ); 647 648 PAM_LOG("Done kuserok()"); 649 650 cleanup: 651 krb5_free_context(pam_context); 652 PAM_LOG("Done cleanup"); 653 654 return (retval); 655 656 } 657 658 /* 659 * password management 660 */ 661 PAM_EXTERN int 662 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 663 int argc __unused, const char *argv[] __unused) 664 { 665 krb5_error_code krbret; 666 krb5_context pam_context; 667 krb5_creds creds; 668 krb5_principal princ; 669 krb5_get_init_creds_opt opts; 670 krb5_data result_code_string, result_string; 671 int result_code, retval; 672 const char *pass; 673 const void *user; 674 char *princ_name, *passdup; 675 char password_prompt[80]; 676 677 if (flags & PAM_PRELIM_CHECK) { 678 /* Nothing to do here. */ 679 return (PAM_SUCCESS); 680 } 681 682 if (!(flags & PAM_UPDATE_AUTHTOK)) { 683 PAM_LOG("Illegal flags argument"); 684 return (PAM_ABORT); 685 } 686 687 retval = pam_get_item(pamh, PAM_USER, &user); 688 if (retval != PAM_SUCCESS) 689 return (retval); 690 691 PAM_LOG("Got user: %s", (const char *)user); 692 693 krbret = krb5_init_context(&pam_context); 694 if (krbret != 0) { 695 PAM_LOG("Error krb5_init_context() failed"); 696 return (PAM_SERVICE_ERR); 697 } 698 699 PAM_LOG("Context initialised"); 700 701 krb5_get_init_creds_opt_init(&opts); 702 703 krb5_get_init_creds_opt_set_tkt_life(&opts, 300); 704 krb5_get_init_creds_opt_set_forwardable(&opts, FALSE); 705 krb5_get_init_creds_opt_set_proxiable(&opts, FALSE); 706 707 PAM_LOG("Credentials options initialised"); 708 709 /* Get principal name */ 710 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 711 if (krbret != 0) { 712 PAM_LOG("Error krb5_parse_name(): %s", 713 krb5_get_err_text(pam_context, krbret)); 714 retval = PAM_USER_UNKNOWN; 715 goto cleanup3; 716 } 717 718 /* Now convert the principal name into something human readable */ 719 princ_name = NULL; 720 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 721 if (krbret != 0) { 722 PAM_LOG("Error krb5_unparse_name(): %s", 723 krb5_get_err_text(pam_context, krbret)); 724 retval = PAM_SERVICE_ERR; 725 goto cleanup2; 726 } 727 728 PAM_LOG("Got principal: %s", princ_name); 729 730 /* Get password */ 731 (void) snprintf(password_prompt, sizeof(password_prompt), 732 PASSWORD_PROMPT, princ_name); 733 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt); 734 if (retval != PAM_SUCCESS) 735 goto cleanup2; 736 737 PAM_LOG("Got password"); 738 739 memset(&creds, 0, sizeof(krb5_creds)); 740 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 741 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 742 if (krbret != 0) { 743 PAM_LOG("Error krb5_get_init_creds_password(): %s", 744 krb5_get_err_text(pam_context, krbret)); 745 retval = PAM_AUTH_ERR; 746 goto cleanup2; 747 } 748 749 PAM_LOG("Credentials established"); 750 751 /* Now get the new password */ 752 for (;;) { 753 retval = pam_get_authtok(pamh, 754 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 755 if (retval != PAM_TRY_AGAIN) 756 break; 757 pam_error(pamh, "Mismatch; try again, EOF to quit."); 758 } 759 if (retval != PAM_SUCCESS) 760 goto cleanup; 761 762 PAM_LOG("Got new password"); 763 764 /* Change it */ 765 if ((passdup = strdup(pass)) == NULL) { 766 retval = PAM_BUF_ERR; 767 goto cleanup; 768 } 769 770 krb5_data_zero(&result_code_string); 771 krb5_data_zero(&result_string); 772 773 krbret = krb5_change_password(pam_context, &creds, passdup, 774 &result_code, &result_code_string, &result_string); 775 free(passdup); 776 if (krbret != 0) { 777 pam_error(pamh, "Unable to set password: %s", 778 krb5_get_err_text(pam_context, krbret)); 779 retval = PAM_AUTHTOK_ERR; 780 goto cleanup; 781 } 782 if (result_code) { 783 pam_info(pamh, "%s%s%.*s", 784 krb5_passwd_result_to_string(pam_context, result_code), 785 result_string.length > 0 ? ": " : "", 786 (int)result_string.length, 787 result_string.length > 0 ? (char *)result_string.data : ""); 788 retval = PAM_AUTHTOK_ERR; 789 } else { 790 PAM_LOG("Password changed"); 791 } 792 793 krb5_data_free(&result_string); 794 krb5_data_free(&result_code_string); 795 796 cleanup: 797 krb5_free_cred_contents(pam_context, &creds); 798 PAM_LOG("Done cleanup"); 799 cleanup2: 800 krb5_free_principal(pam_context, princ); 801 PAM_LOG("Done cleanup2"); 802 cleanup3: 803 if (princ_name) 804 free(princ_name); 805 806 krb5_free_context(pam_context); 807 808 PAM_LOG("Done cleanup3"); 809 810 return (retval); 811 } 812 813 PAM_MODULE_ENTRY("pam_krb5"); 814 815 /* 816 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 817 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 818 * for Debian. 819 * 820 * Verify the Kerberos ticket-granting ticket just retrieved for the 821 * user. If the Kerberos server doesn't respond, assume the user is 822 * trying to fake us out (since we DID just get a TGT from what is 823 * supposedly our KDC). If the host/<host> service is unknown (i.e., 824 * the local keytab doesn't have it), and we cannot find another 825 * service we do have, let her in. 826 * 827 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 828 */ 829 /* ARGSUSED */ 830 static int 831 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 832 char *pam_service, int debug) 833 { 834 krb5_error_code retval; 835 krb5_principal princ; 836 krb5_keyblock *keyblock; 837 krb5_data packet; 838 krb5_auth_context auth_context; 839 char phost[BUFSIZ]; 840 const char *services[3], **service; 841 842 packet.data = 0; 843 844 /* If possible we want to try and verify the ticket we have 845 * received against a keytab. We will try multiple service 846 * principals, including at least the host principal and the PAM 847 * service principal. The host principal is preferred because access 848 * to that key is generally sufficient to compromise root, while the 849 * service key for this PAM service may be less carefully guarded. 850 * It is important to check the keytab first before the KDC so we do 851 * not get spoofed by a fake KDC. 852 */ 853 services[0] = "host"; 854 services[1] = pam_service; 855 services[2] = NULL; 856 keyblock = 0; 857 retval = -1; 858 for (service = &services[0]; *service != NULL; service++) { 859 retval = krb5_sname_to_principal(context, NULL, *service, 860 KRB5_NT_SRV_HST, &princ); 861 if (retval != 0) { 862 if (debug) 863 syslog(LOG_DEBUG, 864 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 865 "krb5_sname_to_principal()", 866 krb5_get_err_text(context, retval)); 867 return -1; 868 } 869 870 /* Extract the name directly. */ 871 strncpy(phost, compat_princ_component(context, princ, 1), 872 BUFSIZ); 873 phost[BUFSIZ - 1] = '\0'; 874 875 /* 876 * Do we have service/<host> keys? 877 * (use default/configured keytab, kvno IGNORE_VNO to get the 878 * first match, and ignore enctype.) 879 */ 880 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 881 &keyblock); 882 if (retval != 0) 883 continue; 884 break; 885 } 886 if (retval != 0) { /* failed to find key */ 887 /* Keytab or service key does not exist */ 888 if (debug) 889 syslog(LOG_DEBUG, 890 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 891 "krb5_kt_read_service_key()", 892 krb5_get_err_text(context, retval)); 893 retval = 0; 894 goto cleanup; 895 } 896 if (keyblock) 897 krb5_free_keyblock(context, keyblock); 898 899 /* Talk to the kdc and construct the ticket. */ 900 auth_context = NULL; 901 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 902 NULL, ccache, &packet); 903 if (auth_context) { 904 krb5_auth_con_free(context, auth_context); 905 auth_context = NULL; /* setup for rd_req */ 906 } 907 if (retval) { 908 if (debug) 909 syslog(LOG_DEBUG, 910 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 911 "krb5_mk_req()", 912 krb5_get_err_text(context, retval)); 913 retval = -1; 914 goto cleanup; 915 } 916 917 /* Try to use the ticket. */ 918 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 919 NULL, NULL); 920 if (retval) { 921 if (debug) 922 syslog(LOG_DEBUG, 923 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 924 "krb5_rd_req()", 925 krb5_get_err_text(context, retval)); 926 retval = -1; 927 } 928 else 929 retval = 1; 930 931 cleanup: 932 if (packet.data) 933 compat_free_data_contents(context, &packet); 934 krb5_free_principal(context, princ); 935 return retval; 936 } 937 938 /* Free the memory for cache_name. Called by pam_end() */ 939 /* ARGSUSED */ 940 static void 941 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 942 { 943 krb5_context pam_context; 944 krb5_ccache ccache; 945 krb5_error_code krbret; 946 947 if (krb5_init_context(&pam_context)) 948 return; 949 950 krbret = krb5_cc_resolve(pam_context, data, &ccache); 951 if (krbret == 0) 952 krb5_cc_destroy(pam_context, ccache); 953 krb5_free_context(pam_context); 954 free(data); 955 } 956 957 #ifdef COMPAT_HEIMDAL 958 #ifdef COMPAT_MIT 959 #error This cannot be MIT and Heimdal compatible! 960 #endif 961 #endif 962 963 #ifndef COMPAT_HEIMDAL 964 #ifndef COMPAT_MIT 965 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 966 #endif 967 #endif 968 969 #ifdef COMPAT_HEIMDAL 970 /* ARGSUSED */ 971 static const char * 972 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 973 { 974 return princ->name.name_string.val[n]; 975 } 976 977 /* ARGSUSED */ 978 static void 979 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 980 { 981 krb5_xfree(data->data); 982 } 983 #endif 984 985 #ifdef COMPAT_MIT 986 static const char * 987 compat_princ_component(krb5_context context, krb5_principal princ, int n) 988 { 989 return krb5_princ_component(context, princ, n)->data; 990 } 991 992 static void 993 compat_free_data_contents(krb5_context context, krb5_data * data) 994 { 995 krb5_free_data_contents(context, data); 996 } 997 #endif 998
Indexes created Mon Sep 29 21:09:56 GMT 2025