pam_krb5.c revision 1.10
1 /* $NetBSD: pam_krb5.c,v 1.10 2005/09/27 14:38:19 tsarna 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 1.10 2005/09/27 14:38:19 tsarna 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); /* XXX */ 366 367 if (!(flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED|PAM_ESTABLISH_CRED))) 368 return (PAM_SERVICE_ERR); 369 370 /* If a persistent cache isn't desired, stop now. */ 371 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE)) 372 return (PAM_SUCCESS); 373 374 PAM_LOG("Establishing credentials"); 375 376 /* Get username */ 377 retval = pam_get_item(pamh, PAM_USER, &user); 378 if (retval != PAM_SUCCESS) 379 return (retval); 380 381 PAM_LOG("Got user: %s", (const char *)user); 382 383 krbret = krb5_init_context(&pam_context); 384 if (krbret != 0) { 385 PAM_LOG("Error krb5_init_context() failed"); 386 return (PAM_SERVICE_ERR); 387 } 388 389 PAM_LOG("Context initialised"); 390 391 euid = geteuid(); /* Usually 0 */ 392 egid = getegid(); 393 394 PAM_LOG("Got euid, egid: %d %d", euid, egid); 395 396 /* Retrieve the temporary cache */ 397 retval = pam_get_data(pamh, "ccache", &cache_data); 398 if (retval != PAM_SUCCESS) { 399 retval = PAM_CRED_UNAVAIL; 400 goto cleanup3; 401 } 402 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 403 if (krbret != 0) { 404 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)cache_data, 405 krb5_get_err_text(pam_context, krbret)); 406 retval = PAM_SERVICE_ERR; 407 goto cleanup3; 408 } 409 410 /* Get the uid. This should exist. */ 411 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 412 pwd == NULL) { 413 retval = PAM_USER_UNKNOWN; 414 goto cleanup3; 415 } 416 417 PAM_LOG("Done getpwnam_r()"); 418 419 /* Avoid following a symlink as root */ 420 if (setegid(pwd->pw_gid)) { 421 retval = PAM_SERVICE_ERR; 422 goto cleanup3; 423 } 424 if (seteuid(pwd->pw_uid)) { 425 retval = PAM_SERVICE_ERR; 426 goto cleanup3; 427 } 428 429 PAM_LOG("Done setegid() & seteuid()"); 430 431 if (flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED)) { 432 cache_name = getenv("KRB5CCNAME"); 433 if (!cache_name) 434 goto cleanup3; 435 } else { 436 /* Get the cache name */ 437 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 438 if (cache_name == NULL) { 439 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 440 cache_name = cache_name_buf; 441 } 442 443 /* XXX potential overflow */ 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 } 478 479 PAM_LOG("Got cache_name: %s", cache_name); 480 481 /* Initialize the new ccache */ 482 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 483 if (krbret != 0) { 484 PAM_LOG("Error krb5_cc_get_principal(): %s", 485 krb5_get_err_text(pam_context, krbret)); 486 retval = PAM_SERVICE_ERR; 487 goto cleanup3; 488 } 489 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 490 if (krbret != 0) { 491 PAM_LOG("Error krb5_cc_resolve(): %s", 492 krb5_get_err_text(pam_context, krbret)); 493 retval = PAM_SERVICE_ERR; 494 goto cleanup2; 495 } 496 497 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 498 if (krbret != 0) { 499 PAM_LOG("Error krb5_cc_initialize(): %s", 500 krb5_get_err_text(pam_context, krbret)); 501 retval = PAM_SERVICE_ERR; 502 goto cleanup2; 503 } 504 505 PAM_LOG("Cache initialised"); 506 507 /* Prepare for iteration over creds */ 508 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 509 if (krbret != 0) { 510 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 511 krb5_get_err_text(pam_context, krbret)); 512 krb5_cc_destroy(pam_context, ccache_perm); 513 retval = PAM_SERVICE_ERR; 514 goto cleanup2; 515 } 516 517 PAM_LOG("Prepared for iteration"); 518 519 /* Copy the creds (should be two of them) */ 520 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 521 &cursor, &creds) == 0)) { 522 523 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 524 if (krbret != 0) { 525 PAM_LOG("Error krb5_cc_store_cred(): %s", 526 krb5_get_err_text(pam_context, krbret)); 527 krb5_cc_destroy(pam_context, ccache_perm); 528 krb5_free_cred_contents(pam_context, &creds); 529 retval = PAM_SERVICE_ERR; 530 goto cleanup2; 531 } 532 533 krb5_free_cred_contents(pam_context, &creds); 534 PAM_LOG("Iteration"); 535 } 536 537 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 538 539 PAM_LOG("Done iterating"); 540 541 if (flags & PAM_ESTABLISH_CRED) { 542 if (strstr(cache_name, "FILE:") == cache_name) { 543 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 544 PAM_LOG("Error chown(): %s", strerror(errno)); 545 krb5_cc_destroy(pam_context, ccache_perm); 546 retval = PAM_SERVICE_ERR; 547 goto cleanup2; 548 } 549 PAM_LOG("Done chown()"); 550 551 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 552 PAM_LOG("Error chmod(): %s", strerror(errno)); 553 krb5_cc_destroy(pam_context, ccache_perm); 554 retval = PAM_SERVICE_ERR; 555 goto cleanup2; 556 } 557 PAM_LOG("Done chmod()"); 558 } 559 } 560 561 krb5_cc_close(pam_context, ccache_perm); 562 563 PAM_LOG("Cache closed"); 564 565 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 566 if (retval != PAM_SUCCESS) { 567 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 568 krb5_cc_destroy(pam_context, ccache_perm); 569 retval = PAM_SERVICE_ERR; 570 goto cleanup2; 571 } 572 573 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 574 575 cleanup2: 576 krb5_free_principal(pam_context, princ); 577 PAM_LOG("Done cleanup2"); 578 cleanup3: 579 krb5_free_context(pam_context); 580 PAM_LOG("Done cleanup3"); 581 582 seteuid(euid); 583 setegid(egid); 584 585 PAM_LOG("Done seteuid() & setegid()"); 586 587 if (cache_name_buf != NULL) 588 free(cache_name_buf); 589 590 return (retval); 591 } 592 593 /* 594 * account management 595 */ 596 PAM_EXTERN int 597 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 598 int argc __unused, const char *argv[] __unused) 599 { 600 krb5_error_code krbret; 601 krb5_context pam_context; 602 krb5_ccache ccache; 603 krb5_principal princ; 604 int retval; 605 const void *user; 606 void *ccache_name; 607 608 retval = pam_get_item(pamh, PAM_USER, &user); 609 if (retval != PAM_SUCCESS) 610 return (retval); 611 612 PAM_LOG("Got user: %s", (const char *)user); 613 614 retval = pam_get_data(pamh, "ccache", &ccache_name); 615 if (retval != PAM_SUCCESS) 616 return (PAM_SUCCESS); 617 618 PAM_LOG("Got credentials"); 619 620 krbret = krb5_init_context(&pam_context); 621 if (krbret != 0) { 622 PAM_LOG("Error krb5_init_context() failed"); 623 return (PAM_PERM_DENIED); 624 } 625 626 PAM_LOG("Context initialised"); 627 628 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 629 if (krbret != 0) { 630 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 631 krb5_get_err_text(pam_context, krbret)); 632 krb5_free_context(pam_context); 633 return (PAM_PERM_DENIED); 634 } 635 636 PAM_LOG("Got ccache %s", (const char *)ccache_name); 637 638 639 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 640 if (krbret != 0) { 641 PAM_LOG("Error krb5_cc_get_principal(): %s", 642 krb5_get_err_text(pam_context, krbret)); 643 retval = PAM_PERM_DENIED;; 644 goto cleanup; 645 } 646 647 PAM_LOG("Got principal"); 648 649 if (krb5_kuserok(pam_context, princ, (const char *)user)) 650 retval = PAM_SUCCESS; 651 else 652 retval = PAM_PERM_DENIED; 653 krb5_free_principal(pam_context, princ); 654 655 PAM_LOG("Done kuserok()"); 656 657 cleanup: 658 krb5_free_context(pam_context); 659 PAM_LOG("Done cleanup"); 660 661 return (retval); 662 663 } 664 665 /* 666 * password management 667 */ 668 PAM_EXTERN int 669 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 670 int argc __unused, const char *argv[] __unused) 671 { 672 krb5_error_code krbret; 673 krb5_context pam_context; 674 krb5_creds creds; 675 krb5_principal princ; 676 krb5_get_init_creds_opt opts; 677 krb5_data result_code_string, result_string; 678 int result_code, retval; 679 const char *pass; 680 const void *user; 681 char *princ_name, *passdup; 682 char password_prompt[80]; 683 684 if (flags & PAM_PRELIM_CHECK) { 685 /* Nothing to do here. */ 686 return (PAM_SUCCESS); 687 } 688 689 if (!(flags & PAM_UPDATE_AUTHTOK)) { 690 PAM_LOG("Illegal flags argument"); 691 return (PAM_ABORT); 692 } 693 694 retval = pam_get_item(pamh, PAM_USER, &user); 695 if (retval != PAM_SUCCESS) 696 return (retval); 697 698 PAM_LOG("Got user: %s", (const char *)user); 699 700 krbret = krb5_init_context(&pam_context); 701 if (krbret != 0) { 702 PAM_LOG("Error krb5_init_context() failed"); 703 return (PAM_SERVICE_ERR); 704 } 705 706 PAM_LOG("Context initialised"); 707 708 krb5_get_init_creds_opt_init(&opts); 709 710 krb5_get_init_creds_opt_set_tkt_life(&opts, 300); 711 krb5_get_init_creds_opt_set_forwardable(&opts, FALSE); 712 krb5_get_init_creds_opt_set_proxiable(&opts, FALSE); 713 714 PAM_LOG("Credentials options initialised"); 715 716 /* Get principal name */ 717 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 718 if (krbret != 0) { 719 PAM_LOG("Error krb5_parse_name(): %s", 720 krb5_get_err_text(pam_context, krbret)); 721 retval = PAM_USER_UNKNOWN; 722 goto cleanup3; 723 } 724 725 /* Now convert the principal name into something human readable */ 726 princ_name = NULL; 727 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 728 if (krbret != 0) { 729 PAM_LOG("Error krb5_unparse_name(): %s", 730 krb5_get_err_text(pam_context, krbret)); 731 retval = PAM_SERVICE_ERR; 732 goto cleanup2; 733 } 734 735 PAM_LOG("Got principal: %s", princ_name); 736 737 /* Get password */ 738 (void) snprintf(password_prompt, sizeof(password_prompt), 739 PASSWORD_PROMPT, princ_name); 740 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt); 741 if (retval != PAM_SUCCESS) 742 goto cleanup2; 743 744 PAM_LOG("Got password"); 745 746 memset(&creds, 0, sizeof(krb5_creds)); 747 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 748 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 749 if (krbret != 0) { 750 PAM_LOG("Error krb5_get_init_creds_password(): %s", 751 krb5_get_err_text(pam_context, krbret)); 752 retval = PAM_AUTH_ERR; 753 goto cleanup2; 754 } 755 756 PAM_LOG("Credentials established"); 757 758 /* Now get the new password */ 759 for (;;) { 760 retval = pam_get_authtok(pamh, 761 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 762 if (retval != PAM_TRY_AGAIN) 763 break; 764 pam_error(pamh, "Mismatch; try again, EOF to quit."); 765 } 766 if (retval != PAM_SUCCESS) 767 goto cleanup; 768 769 PAM_LOG("Got new password"); 770 771 /* Change it */ 772 if ((passdup = strdup(pass)) == NULL) { 773 retval = PAM_BUF_ERR; 774 goto cleanup; 775 } 776 777 krb5_data_zero(&result_code_string); 778 krb5_data_zero(&result_string); 779 780 krbret = krb5_change_password(pam_context, &creds, passdup, 781 &result_code, &result_code_string, &result_string); 782 free(passdup); 783 if (krbret != 0) { 784 pam_error(pamh, "Unable to set password: %s", 785 krb5_get_err_text(pam_context, krbret)); 786 retval = PAM_AUTHTOK_ERR; 787 goto cleanup; 788 } 789 if (result_code) { 790 pam_info(pamh, "%s%s%.*s", 791 krb5_passwd_result_to_string(pam_context, result_code), 792 result_string.length > 0 ? ": " : "", 793 (int)result_string.length, 794 result_string.length > 0 ? (char *)result_string.data : ""); 795 retval = PAM_AUTHTOK_ERR; 796 } else { 797 PAM_LOG("Password changed"); 798 } 799 800 krb5_data_free(&result_string); 801 krb5_data_free(&result_code_string); 802 803 cleanup: 804 krb5_free_cred_contents(pam_context, &creds); 805 PAM_LOG("Done cleanup"); 806 cleanup2: 807 krb5_free_principal(pam_context, princ); 808 PAM_LOG("Done cleanup2"); 809 cleanup3: 810 if (princ_name) 811 free(princ_name); 812 813 krb5_free_context(pam_context); 814 815 PAM_LOG("Done cleanup3"); 816 817 return (retval); 818 } 819 820 PAM_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 (at) 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 */ 837 static int 838 verify_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 syslog(LOG_DEBUG, 871 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 872 "krb5_sname_to_principal()", 873 krb5_get_err_text(context, retval)); 874 return -1; 875 } 876 877 /* Extract the name directly. */ 878 strncpy(phost, compat_princ_component(context, princ, 1), 879 BUFSIZ); 880 phost[BUFSIZ - 1] = '\0'; 881 882 /* 883 * Do we have service/<host> keys? 884 * (use default/configured keytab, kvno IGNORE_VNO to get the 885 * first match, and ignore enctype.) 886 */ 887 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 888 &keyblock); 889 if (retval != 0) 890 continue; 891 break; 892 } 893 if (retval != 0) { /* failed to find key */ 894 /* Keytab or service key does not exist */ 895 if (debug) 896 syslog(LOG_DEBUG, 897 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 898 "krb5_kt_read_service_key()", 899 krb5_get_err_text(context, retval)); 900 retval = 0; 901 goto cleanup; 902 } 903 if (keyblock) 904 krb5_free_keyblock(context, keyblock); 905 906 /* Talk to the kdc and construct the ticket. */ 907 auth_context = NULL; 908 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 909 NULL, ccache, &packet); 910 if (auth_context) { 911 krb5_auth_con_free(context, auth_context); 912 auth_context = NULL; /* setup for rd_req */ 913 } 914 if (retval) { 915 if (debug) 916 syslog(LOG_DEBUG, 917 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 918 "krb5_mk_req()", 919 krb5_get_err_text(context, retval)); 920 retval = -1; 921 goto cleanup; 922 } 923 924 /* Try to use the ticket. */ 925 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 926 NULL, NULL); 927 if (retval) { 928 if (debug) 929 syslog(LOG_DEBUG, 930 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 931 "krb5_rd_req()", 932 krb5_get_err_text(context, retval)); 933 retval = -1; 934 } 935 else 936 retval = 1; 937 938 cleanup: 939 if (packet.data) 940 compat_free_data_contents(context, &packet); 941 krb5_free_principal(context, princ); 942 return retval; 943 } 944 945 /* Free the memory for cache_name. Called by pam_end() */ 946 /* ARGSUSED */ 947 static void 948 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 949 { 950 krb5_context pam_context; 951 krb5_ccache ccache; 952 krb5_error_code krbret; 953 954 if (krb5_init_context(&pam_context)) 955 return; 956 957 krbret = krb5_cc_resolve(pam_context, data, &ccache); 958 if (krbret == 0) 959 krb5_cc_destroy(pam_context, ccache); 960 krb5_free_context(pam_context); 961 free(data); 962 } 963 964 #ifdef COMPAT_HEIMDAL 965 #ifdef COMPAT_MIT 966 #error This cannot be MIT and Heimdal compatible! 967 #endif 968 #endif 969 970 #ifndef COMPAT_HEIMDAL 971 #ifndef COMPAT_MIT 972 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 973 #endif 974 #endif 975 976 #ifdef COMPAT_HEIMDAL 977 /* ARGSUSED */ 978 static const char * 979 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 980 { 981 return princ->name.name_string.val[n]; 982 } 983 984 /* ARGSUSED */ 985 static void 986 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 987 { 988 krb5_xfree(data->data); 989 } 990 #endif 991 992 #ifdef COMPAT_MIT 993 static const char * 994 compat_princ_component(krb5_context context, krb5_principal princ, int n) 995 { 996 return krb5_princ_component(context, princ, n)->data; 997 } 998 999 static void 1000 compat_free_data_contents(krb5_context context, krb5_data * data) 1001 { 1002 krb5_free_data_contents(context, data); 1003 } 1004 #endif 1005
Indexes created Mon Sep 29 21:09:56 GMT 2025