pam_krb5.c revision 1.8
1 /* $NetBSD: pam_krb5.c,v 1.8 2005/04/19 03:15:35 christos 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 1.8 2005/04/19 03:15:35 christos 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 retval = PAM_USER_UNKNOWN; 419 goto cleanup3; 420 } 421 422 PAM_LOG("Done getpwnam_r()"); 423 424 /* Avoid following a symlink as root */ 425 if (setegid(pwd->pw_gid)) { 426 retval = PAM_SERVICE_ERR; 427 goto cleanup3; 428 } 429 if (seteuid(pwd->pw_uid)) { 430 retval = PAM_SERVICE_ERR; 431 goto cleanup3; 432 } 433 434 PAM_LOG("Done setegid() & seteuid()"); 435 436 /* 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 p = calloc(PATH_MAX + 16, sizeof(char)); 444 q = cache_name; 445 446 if (p == NULL) { 447 PAM_LOG("Error malloc(): failure"); 448 retval = PAM_BUF_ERR; 449 goto cleanup3; 450 } 451 cache_name = p; 452 453 /* convert %u and %p */ 454 while (*q) { 455 if (*q == '%') { 456 q++; 457 if (*q == 'u') { 458 sprintf(p, "%d", pwd->pw_uid); 459 p += strlen(p); 460 } 461 else if (*q == 'p') { 462 sprintf(p, "%d", getpid()); 463 p += strlen(p); 464 } 465 else { 466 /* Not a special token */ 467 *p++ = '%'; 468 q--; 469 } 470 q++; 471 } 472 else { 473 *p++ = *q++; 474 } 475 } 476 477 PAM_LOG("Got cache_name: %s", cache_name); 478 479 /* Initialize the new ccache */ 480 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 481 if (krbret != 0) { 482 PAM_LOG("Error krb5_cc_get_principal(): %s", 483 krb5_get_err_text(pam_context, krbret)); 484 retval = PAM_SERVICE_ERR; 485 goto cleanup3; 486 } 487 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 488 if (krbret != 0) { 489 PAM_LOG("Error krb5_cc_resolve(): %s", 490 krb5_get_err_text(pam_context, krbret)); 491 retval = PAM_SERVICE_ERR; 492 goto cleanup2; 493 } 494 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 495 if (krbret != 0) { 496 PAM_LOG("Error krb5_cc_initialize(): %s", 497 krb5_get_err_text(pam_context, krbret)); 498 retval = PAM_SERVICE_ERR; 499 goto cleanup2; 500 } 501 502 PAM_LOG("Cache initialised"); 503 504 /* Prepare for iteration over creds */ 505 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 506 if (krbret != 0) { 507 PAM_LOG("Error krb5_cc_start_seq_get(): %s", 508 krb5_get_err_text(pam_context, krbret)); 509 krb5_cc_destroy(pam_context, ccache_perm); 510 retval = PAM_SERVICE_ERR; 511 goto cleanup2; 512 } 513 514 PAM_LOG("Prepared for iteration"); 515 516 /* Copy the creds (should be two of them) */ 517 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 518 &cursor, &creds) == 0)) { 519 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 520 if (krbret != 0) { 521 PAM_LOG("Error krb5_cc_store_cred(): %s", 522 krb5_get_err_text(pam_context, krbret)); 523 krb5_cc_destroy(pam_context, ccache_perm); 524 krb5_free_cred_contents(pam_context, &creds); 525 retval = PAM_SERVICE_ERR; 526 goto cleanup2; 527 } 528 krb5_free_cred_contents(pam_context, &creds); 529 PAM_LOG("Iteration"); 530 } 531 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 532 533 PAM_LOG("Done iterating"); 534 535 if (strstr(cache_name, "FILE:") == cache_name) { 536 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 537 PAM_LOG("Error chown(): %s", strerror(errno)); 538 krb5_cc_destroy(pam_context, ccache_perm); 539 retval = PAM_SERVICE_ERR; 540 goto cleanup2; 541 } 542 PAM_LOG("Done chown()"); 543 544 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 545 PAM_LOG("Error chmod(): %s", strerror(errno)); 546 krb5_cc_destroy(pam_context, ccache_perm); 547 retval = PAM_SERVICE_ERR; 548 goto cleanup2; 549 } 550 PAM_LOG("Done chmod()"); 551 } 552 553 krb5_cc_close(pam_context, ccache_perm); 554 555 PAM_LOG("Cache closed"); 556 557 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 558 if (retval != PAM_SUCCESS) { 559 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 560 krb5_cc_destroy(pam_context, ccache_perm); 561 retval = PAM_SERVICE_ERR; 562 goto cleanup2; 563 } 564 565 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 566 567 cleanup2: 568 krb5_free_principal(pam_context, princ); 569 PAM_LOG("Done cleanup2"); 570 cleanup3: 571 krb5_free_context(pam_context); 572 PAM_LOG("Done cleanup3"); 573 574 seteuid(euid); 575 setegid(egid); 576 577 PAM_LOG("Done seteuid() & setegid()"); 578 579 if (cache_name_buf != NULL) 580 free(cache_name_buf); 581 582 return (retval); 583 } 584 585 /* 586 * account management 587 */ 588 PAM_EXTERN int 589 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 590 int argc __unused, const char *argv[] __unused) 591 { 592 krb5_error_code krbret; 593 krb5_context pam_context; 594 krb5_ccache ccache; 595 krb5_principal princ; 596 int retval; 597 const void *user; 598 void *ccache_name; 599 600 retval = pam_get_item(pamh, PAM_USER, &user); 601 if (retval != PAM_SUCCESS) 602 return (retval); 603 604 PAM_LOG("Got user: %s", (const char *)user); 605 606 retval = pam_get_data(pamh, "ccache", &ccache_name); 607 if (retval != PAM_SUCCESS) 608 return (PAM_SUCCESS); 609 610 PAM_LOG("Got credentials"); 611 612 krbret = krb5_init_context(&pam_context); 613 if (krbret != 0) { 614 PAM_LOG("Error krb5_init_context() failed"); 615 return (PAM_PERM_DENIED); 616 } 617 618 PAM_LOG("Context initialised"); 619 620 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 621 if (krbret != 0) { 622 PAM_LOG("Error krb5_cc_resolve(\"%s\"): %s", (const char *)ccache_name, 623 krb5_get_err_text(pam_context, krbret)); 624 krb5_free_context(pam_context); 625 return (PAM_PERM_DENIED); 626 } 627 628 PAM_LOG("Got ccache %s", (const char *)ccache_name); 629 630 631 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 632 if (krbret != 0) { 633 PAM_LOG("Error krb5_cc_get_principal(): %s", 634 krb5_get_err_text(pam_context, krbret)); 635 retval = PAM_PERM_DENIED;; 636 goto cleanup; 637 } 638 639 PAM_LOG("Got principal"); 640 641 if (krb5_kuserok(pam_context, princ, (const char *)user)) 642 retval = PAM_SUCCESS; 643 else 644 retval = PAM_PERM_DENIED; 645 krb5_free_principal(pam_context, princ); 646 647 PAM_LOG("Done kuserok()"); 648 649 cleanup: 650 krb5_free_context(pam_context); 651 PAM_LOG("Done cleanup"); 652 653 return (retval); 654 655 } 656 657 /* 658 * password management 659 */ 660 PAM_EXTERN int 661 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 662 int argc __unused, const char *argv[] __unused) 663 { 664 krb5_error_code krbret; 665 krb5_context pam_context; 666 krb5_creds creds; 667 krb5_principal princ; 668 krb5_get_init_creds_opt opts; 669 krb5_data result_code_string, result_string; 670 int result_code, retval; 671 const char *pass; 672 const void *user; 673 char *princ_name, *passdup; 674 char password_prompt[80]; 675 676 if (flags & PAM_PRELIM_CHECK) { 677 /* Nothing to do here. */ 678 return (PAM_SUCCESS); 679 } 680 681 if (!(flags & PAM_UPDATE_AUTHTOK)) { 682 PAM_LOG("Illegal flags argument"); 683 return (PAM_ABORT); 684 } 685 686 retval = pam_get_item(pamh, PAM_USER, &user); 687 if (retval != PAM_SUCCESS) 688 return (retval); 689 690 PAM_LOG("Got user: %s", (const char *)user); 691 692 krbret = krb5_init_context(&pam_context); 693 if (krbret != 0) { 694 PAM_LOG("Error krb5_init_context() failed"); 695 return (PAM_SERVICE_ERR); 696 } 697 698 PAM_LOG("Context initialised"); 699 700 krb5_get_init_creds_opt_init(&opts); 701 702 krb5_get_init_creds_opt_set_tkt_life(&opts, 300); 703 krb5_get_init_creds_opt_set_forwardable(&opts, FALSE); 704 krb5_get_init_creds_opt_set_proxiable(&opts, FALSE); 705 706 PAM_LOG("Credentials options initialised"); 707 708 /* Get principal name */ 709 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 710 if (krbret != 0) { 711 PAM_LOG("Error krb5_parse_name(): %s", 712 krb5_get_err_text(pam_context, krbret)); 713 retval = PAM_USER_UNKNOWN; 714 goto cleanup3; 715 } 716 717 /* Now convert the principal name into something human readable */ 718 princ_name = NULL; 719 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 720 if (krbret != 0) { 721 PAM_LOG("Error krb5_unparse_name(): %s", 722 krb5_get_err_text(pam_context, krbret)); 723 retval = PAM_SERVICE_ERR; 724 goto cleanup2; 725 } 726 727 PAM_LOG("Got principal: %s", princ_name); 728 729 /* Get password */ 730 (void) snprintf(password_prompt, sizeof(password_prompt), 731 PASSWORD_PROMPT, princ_name); 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 memset(&creds, 0, sizeof(krb5_creds)); 739 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 740 pass, NULL, pamh, 0, "kadmin/changepw", &opts); 741 if (krbret != 0) { 742 PAM_LOG("Error krb5_get_init_creds_password(): %s", 743 krb5_get_err_text(pam_context, krbret)); 744 retval = PAM_AUTH_ERR; 745 goto cleanup2; 746 } 747 748 PAM_LOG("Credentials established"); 749 750 /* Now get the new password */ 751 for (;;) { 752 retval = pam_get_authtok(pamh, 753 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 754 if (retval != PAM_TRY_AGAIN) 755 break; 756 pam_error(pamh, "Mismatch; try again, EOF to quit."); 757 } 758 if (retval != PAM_SUCCESS) 759 goto cleanup; 760 761 PAM_LOG("Got new password"); 762 763 /* Change it */ 764 if ((passdup = strdup(pass)) == NULL) { 765 retval = PAM_BUF_ERR; 766 goto cleanup; 767 } 768 769 krb5_data_zero(&result_code_string); 770 krb5_data_zero(&result_string); 771 772 krbret = krb5_change_password(pam_context, &creds, passdup, 773 &result_code, &result_code_string, &result_string); 774 free(passdup); 775 if (krbret != 0) { 776 pam_error(pamh, "Unable to set password: %s", 777 krb5_get_err_text(pam_context, krbret)); 778 retval = PAM_AUTHTOK_ERR; 779 goto cleanup; 780 } 781 if (result_code) { 782 pam_info(pamh, "%s%s%.*s", 783 krb5_passwd_result_to_string(pam_context, result_code), 784 result_string.length > 0 ? ": " : "", 785 (int)result_string.length, 786 result_string.length > 0 ? (char *)result_string.data : ""); 787 retval = PAM_AUTHTOK_ERR; 788 } else { 789 PAM_LOG("Password changed"); 790 } 791 792 krb5_data_free(&result_string); 793 krb5_data_free(&result_code_string); 794 795 cleanup: 796 krb5_free_cred_contents(pam_context, &creds); 797 PAM_LOG("Done cleanup"); 798 cleanup2: 799 krb5_free_principal(pam_context, princ); 800 PAM_LOG("Done cleanup2"); 801 cleanup3: 802 if (princ_name) 803 free(princ_name); 804 805 krb5_free_context(pam_context); 806 807 PAM_LOG("Done cleanup3"); 808 809 return (retval); 810 } 811 812 PAM_MODULE_ENTRY("pam_krb5"); 813 814 /* 815 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 816 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 817 * for Debian. 818 * 819 * Verify the Kerberos ticket-granting ticket just retrieved for the 820 * user. If the Kerberos server doesn't respond, assume the user is 821 * trying to fake us out (since we DID just get a TGT from what is 822 * supposedly our KDC). If the host/<host> service is unknown (i.e., 823 * the local keytab doesn't have it), and we cannot find another 824 * service we do have, let her in. 825 * 826 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 827 */ 828 /* ARGSUSED */ 829 static int 830 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 831 char *pam_service, int debug) 832 { 833 krb5_error_code retval; 834 krb5_principal princ; 835 krb5_keyblock *keyblock; 836 krb5_data packet; 837 krb5_auth_context auth_context; 838 char phost[BUFSIZ]; 839 const char *services[3], **service; 840 841 packet.data = 0; 842 843 /* If possible we want to try and verify the ticket we have 844 * received against a keytab. We will try multiple service 845 * principals, including at least the host principal and the PAM 846 * service principal. The host principal is preferred because access 847 * to that key is generally sufficient to compromise root, while the 848 * service key for this PAM service may be less carefully guarded. 849 * It is important to check the keytab first before the KDC so we do 850 * not get spoofed by a fake KDC. 851 */ 852 services[0] = "host"; 853 services[1] = pam_service; 854 services[2] = NULL; 855 keyblock = 0; 856 retval = -1; 857 for (service = &services[0]; *service != NULL; service++) { 858 retval = krb5_sname_to_principal(context, NULL, *service, 859 KRB5_NT_SRV_HST, &princ); 860 if (retval != 0) { 861 if (debug) 862 syslog(LOG_DEBUG, 863 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 864 "krb5_sname_to_principal()", 865 krb5_get_err_text(context, retval)); 866 return -1; 867 } 868 869 /* Extract the name directly. */ 870 strncpy(phost, compat_princ_component(context, princ, 1), 871 BUFSIZ); 872 phost[BUFSIZ - 1] = '\0'; 873 874 /* 875 * Do we have service/<host> keys? 876 * (use default/configured keytab, kvno IGNORE_VNO to get the 877 * first match, and ignore enctype.) 878 */ 879 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 880 &keyblock); 881 if (retval != 0) 882 continue; 883 break; 884 } 885 if (retval != 0) { /* failed to find key */ 886 /* Keytab or service key does not exist */ 887 if (debug) 888 syslog(LOG_DEBUG, 889 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 890 "krb5_kt_read_service_key()", 891 krb5_get_err_text(context, retval)); 892 retval = 0; 893 goto cleanup; 894 } 895 if (keyblock) 896 krb5_free_keyblock(context, keyblock); 897 898 /* Talk to the kdc and construct the ticket. */ 899 auth_context = NULL; 900 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 901 NULL, ccache, &packet); 902 if (auth_context) { 903 krb5_auth_con_free(context, auth_context); 904 auth_context = NULL; /* setup for rd_req */ 905 } 906 if (retval) { 907 if (debug) 908 syslog(LOG_DEBUG, 909 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 910 "krb5_mk_req()", 911 krb5_get_err_text(context, retval)); 912 retval = -1; 913 goto cleanup; 914 } 915 916 /* Try to use the ticket. */ 917 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 918 NULL, NULL); 919 if (retval) { 920 if (debug) 921 syslog(LOG_DEBUG, 922 "pam_krb5: verify_krb_v5_tgt(): %s: %s", 923 "krb5_rd_req()", 924 krb5_get_err_text(context, retval)); 925 retval = -1; 926 } 927 else 928 retval = 1; 929 930 cleanup: 931 if (packet.data) 932 compat_free_data_contents(context, &packet); 933 krb5_free_principal(context, princ); 934 return retval; 935 } 936 937 /* Free the memory for cache_name. Called by pam_end() */ 938 /* ARGSUSED */ 939 static void 940 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 941 { 942 krb5_context pam_context; 943 krb5_ccache ccache; 944 krb5_error_code krbret; 945 946 if (krb5_init_context(&pam_context)) 947 return; 948 949 krbret = krb5_cc_resolve(pam_context, data, &ccache); 950 if (krbret == 0) 951 krb5_cc_destroy(pam_context, ccache); 952 krb5_free_context(pam_context); 953 free(data); 954 } 955 956 #ifdef COMPAT_HEIMDAL 957 #ifdef COMPAT_MIT 958 #error This cannot be MIT and Heimdal compatible! 959 #endif 960 #endif 961 962 #ifndef COMPAT_HEIMDAL 963 #ifndef COMPAT_MIT 964 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 965 #endif 966 #endif 967 968 #ifdef COMPAT_HEIMDAL 969 /* ARGSUSED */ 970 static const char * 971 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 972 { 973 return princ->name.name_string.val[n]; 974 } 975 976 /* ARGSUSED */ 977 static void 978 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 979 { 980 krb5_xfree(data->data); 981 } 982 #endif 983 984 #ifdef COMPAT_MIT 985 static const char * 986 compat_princ_component(krb5_context context, krb5_principal princ, int n) 987 { 988 return krb5_princ_component(context, princ, n)->data; 989 } 990 991 static void 992 compat_free_data_contents(krb5_context context, krb5_data * data) 993 { 994 krb5_free_data_contents(context, data); 995 } 996 #endif 997
Indexes created Mon Sep 29 21:09:56 GMT 2025