pam_krb5.c revision 1.26
1 /* $NetBSD: pam_krb5.c,v 1.26 2013/12/28 18:04:03 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 1.26 2013/12/28 18:04:03 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 #include <krb5/parse_time.h> 73 74 #define PAM_SM_AUTH 75 #define PAM_SM_ACCOUNT 76 #define PAM_SM_PASSWORD 77 78 #include <security/pam_appl.h> 79 #include <security/pam_modules.h> 80 #include <security/pam_mod_misc.h> 81 #include <security/openpam.h> 82 83 #define COMPAT_HEIMDAL 84 /* #define COMPAT_MIT */ 85 86 static void log_krb5(krb5_context, krb5_error_code, struct syslog_data *, 87 const char *, ...) __printflike(4, 5); 88 static int verify_krb_v5_tgt(krb5_context, krb5_ccache, char *, int); 89 static void cleanup_cache(pam_handle_t *, void *, int); 90 static const char *compat_princ_component(krb5_context, krb5_principal, int); 91 static void compat_free_data_contents(krb5_context, krb5_data *); 92 93 #define USER_PROMPT "Username: " 94 #define PASSWORD_PROMPT "%s's password:" 95 #define NEW_PASSWORD_PROMPT "New Password:" 96 97 #define PAM_OPT_CCACHE "ccache" 98 #define PAM_OPT_DEBUG "debug" 99 #define PAM_OPT_FORWARDABLE "forwardable" 100 #define PAM_OPT_RENEWABLE "renewable" 101 #define PAM_OPT_NO_CCACHE "no_ccache" 102 #define PAM_OPT_REUSE_CCACHE "reuse_ccache" 103 104 /* 105 * authentication management 106 */ 107 PAM_EXTERN int 108 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused, 109 int argc __unused, const char *argv[] __unused) 110 { 111 krb5_error_code krbret; 112 krb5_context pam_context; 113 krb5_creds creds; 114 krb5_principal princ; 115 krb5_ccache ccache; 116 krb5_get_init_creds_opt *opts = NULL; 117 struct passwd *pwd, pwres; 118 int retval; 119 const void *ccache_data; 120 const char *user, *pass; 121 const void *sourceuser, *service; 122 char *principal, *princ_name, *ccache_name, luser[32], *srvdup; 123 char password_prompt[80]; 124 char pwbuf[1024]; 125 const char *rtime; 126 127 princ_name = NULL; 128 retval = pam_get_user(pamh, &user, USER_PROMPT); 129 if (retval != PAM_SUCCESS) 130 return (retval); 131 132 PAM_LOG("Got user: %s", user); 133 134 retval = pam_get_item(pamh, PAM_RUSER, &sourceuser); 135 if (retval != PAM_SUCCESS) 136 return (retval); 137 138 PAM_LOG("Got ruser: %s", (const char *)sourceuser); 139 140 service = NULL; 141 pam_get_item(pamh, PAM_SERVICE, &service); 142 if (service == NULL) 143 service = "unknown"; 144 145 PAM_LOG("Got service: %s", (const char *)service); 146 147 krbret = krb5_init_context(&pam_context); 148 if (krbret != 0) { 149 PAM_VERBOSE_ERROR("Kerberos 5 error"); 150 return (PAM_SERVICE_ERR); 151 } 152 153 PAM_LOG("Context initialised"); 154 155 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 156 if (krbret != 0) { 157 PAM_VERBOSE_ERROR("Kerberos 5 error"); 158 return (PAM_SERVICE_ERR); 159 } 160 161 if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE)) 162 krb5_get_init_creds_opt_set_forwardable(opts, 1); 163 164 if ((rtime = openpam_get_option(pamh, PAM_OPT_RENEWABLE)) != NULL) { 165 krb5_deltat renew; 166 char rbuf[80], *rp; 167 168 if (*rtime) { 169 (void)strlcpy(rbuf, rtime, sizeof(rbuf)); 170 rtime = rbuf; 171 for (rp = rbuf; *rp; rp++) 172 if (*rp == '_') 173 *rp = ' '; 174 } 175 else 176 rtime = "1 month"; 177 renew = parse_time(rtime, "s"); 178 krb5_get_init_creds_opt_set_renew_life(opts, renew); 179 } 180 181 182 183 PAM_LOG("Credentials initialised"); 184 185 krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE); 186 if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) { 187 PAM_VERBOSE_ERROR("Kerberos 5 error"); 188 retval = PAM_SERVICE_ERR; 189 goto cleanup3; 190 } 191 192 PAM_LOG("Done krb5_cc_register()"); 193 194 /* Get principal name */ 195 if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) 196 asprintf(&principal, "%s/%s", (const char *)sourceuser, user); 197 else 198 principal = strdup(user); 199 200 PAM_LOG("Created principal: %s", principal); 201 202 krbret = krb5_parse_name(pam_context, principal, &princ); 203 free(principal); 204 if (krbret != 0) { 205 log_krb5(pam_context, krbret, NULL, "krb5_parse_name"); 206 PAM_VERBOSE_ERROR("Kerberos 5 error"); 207 retval = PAM_SERVICE_ERR; 208 goto cleanup3; 209 } 210 211 PAM_LOG("Done krb5_parse_name()"); 212 213 /* Now convert the principal name into something human readable */ 214 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 215 if (krbret != 0) { 216 log_krb5(pam_context, krbret, NULL, "krb5_unparse_name"); 217 PAM_VERBOSE_ERROR("Kerberos 5 error"); 218 retval = PAM_SERVICE_ERR; 219 goto cleanup2; 220 } 221 222 PAM_LOG("Got principal: %s", princ_name); 223 224 /* Get password */ 225 (void) snprintf(password_prompt, sizeof(password_prompt), 226 PASSWORD_PROMPT, princ_name); 227 retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, password_prompt); 228 if (retval != PAM_SUCCESS) 229 goto cleanup2; 230 231 PAM_LOG("Got password"); 232 233 /* Verify the local user exists (AFTER getting the password) */ 234 if (strchr(user, '@')) { 235 /* get a local account name for this principal */ 236 krbret = krb5_aname_to_localname(pam_context, princ, 237 sizeof(luser), luser); 238 if (krbret != 0) { 239 PAM_VERBOSE_ERROR("Kerberos 5 error"); 240 log_krb5(pam_context, krbret, NULL, 241 "krb5_aname_to_localname"); 242 retval = PAM_USER_UNKNOWN; 243 goto cleanup2; 244 } 245 246 retval = pam_set_item(pamh, PAM_USER, luser); 247 if (retval != PAM_SUCCESS) 248 goto cleanup2; 249 250 PAM_LOG("PAM_USER Redone"); 251 } 252 253 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 254 pwd == NULL) { 255 retval = PAM_USER_UNKNOWN; 256 goto cleanup2; 257 } 258 259 PAM_LOG("Done getpwnam_r()"); 260 261 /* Get a TGT */ 262 memset(&creds, 0, sizeof(krb5_creds)); 263 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 264 pass, NULL, pamh, 0, NULL, opts); 265 if (krbret != 0) { 266 PAM_VERBOSE_ERROR("Kerberos 5 error"); 267 log_krb5(pam_context, krbret, NULL, 268 "krb5_get_init_creds_password"); 269 retval = PAM_AUTH_ERR; 270 goto cleanup2; 271 } 272 273 PAM_LOG("Got TGT"); 274 275 /* Generate a temporary cache */ 276 krbret = krb5_cc_new_unique(pam_context, "MEMORY", NULL, &ccache); 277 if (krbret != 0) { 278 PAM_VERBOSE_ERROR("Kerberos 5 error"); 279 log_krb5(pam_context, krbret, NULL, "krb5_cc_gen_new"); 280 retval = PAM_SERVICE_ERR; 281 goto cleanup; 282 } 283 krbret = krb5_cc_initialize(pam_context, ccache, princ); 284 if (krbret != 0) { 285 PAM_VERBOSE_ERROR("Kerberos 5 error"); 286 log_krb5(pam_context, krbret, NULL, "krb5_cc_initialize"); 287 retval = PAM_SERVICE_ERR; 288 goto cleanup; 289 } 290 krbret = krb5_cc_store_cred(pam_context, ccache, &creds); 291 if (krbret != 0) { 292 PAM_VERBOSE_ERROR("Kerberos 5 error"); 293 log_krb5(pam_context, krbret, NULL, "krb5_cc_store_cred"); 294 krb5_cc_destroy(pam_context, ccache); 295 retval = PAM_SERVICE_ERR; 296 goto cleanup; 297 } 298 299 PAM_LOG("Credentials stashed"); 300 301 /* Verify them */ 302 if ((srvdup = strdup(service)) == NULL) { 303 retval = PAM_BUF_ERR; 304 goto cleanup; 305 } 306 krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup, 307 openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0); 308 free(srvdup); 309 if (krbret == -1) { 310 PAM_VERBOSE_ERROR("Kerberos 5 error"); 311 krb5_cc_destroy(pam_context, ccache); 312 retval = PAM_AUTH_ERR; 313 goto cleanup; 314 } 315 316 PAM_LOG("Credentials stash verified"); 317 318 retval = pam_get_data(pamh, "ccache", &ccache_data); 319 if (retval == PAM_SUCCESS) { 320 krb5_cc_destroy(pam_context, ccache); 321 PAM_VERBOSE_ERROR("Kerberos 5 error"); 322 retval = PAM_AUTH_ERR; 323 goto cleanup; 324 } 325 326 PAM_LOG("Credentials stash not pre-existing"); 327 328 asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context, 329 ccache), krb5_cc_get_name(pam_context, ccache)); 330 if (ccache_name == NULL) { 331 PAM_VERBOSE_ERROR("Kerberos 5 error"); 332 retval = PAM_BUF_ERR; 333 goto cleanup; 334 } 335 retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache); 336 if (retval != 0) { 337 krb5_cc_destroy(pam_context, ccache); 338 PAM_VERBOSE_ERROR("Kerberos 5 error"); 339 retval = PAM_SERVICE_ERR; 340 goto cleanup; 341 } 342 343 PAM_LOG("Credentials stash saved"); 344 345 cleanup: 346 krb5_free_cred_contents(pam_context, &creds); 347 PAM_LOG("Done cleanup"); 348 cleanup2: 349 krb5_free_principal(pam_context, princ); 350 PAM_LOG("Done cleanup2"); 351 cleanup3: 352 if (princ_name) 353 free(princ_name); 354 355 if (opts) 356 krb5_get_init_creds_opt_free(pam_context, opts); 357 358 krb5_free_context(pam_context); 359 360 PAM_LOG("Done cleanup3"); 361 362 if (retval != PAM_SUCCESS) 363 PAM_VERBOSE_ERROR("Kerberos 5 refuses you"); 364 365 return (retval); 366 } 367 368 PAM_EXTERN int 369 pam_sm_setcred(pam_handle_t *pamh, int flags, 370 int argc __unused, const char *argv[] __unused) 371 { 372 373 krb5_error_code krbret; 374 krb5_context pam_context; 375 krb5_principal princ; 376 krb5_creds creds; 377 krb5_ccache ccache_temp, ccache_perm; 378 krb5_cc_cursor cursor; 379 struct passwd *pwd = NULL, pwres; 380 int retval; 381 const char *cache_name, *q; 382 const void *user; 383 const void *cache_data; 384 char *cache_name_buf = NULL, *p, *cache_name_buf2 = NULL; 385 char pwbuf[1024]; 386 387 uid_t euid; 388 gid_t egid; 389 390 if (flags & PAM_DELETE_CRED) 391 return (PAM_SUCCESS); /* XXX */ 392 393 if (!(flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED|PAM_ESTABLISH_CRED))) 394 return (PAM_SERVICE_ERR); 395 396 /* If a persistent cache isn't desired, stop now. */ 397 if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE)) 398 return (PAM_SUCCESS); 399 400 PAM_LOG("Establishing credentials"); 401 402 /* Get username */ 403 retval = pam_get_item(pamh, PAM_USER, &user); 404 if (retval != PAM_SUCCESS) 405 return (retval); 406 407 PAM_LOG("Got user: %s", (const char *)user); 408 409 krbret = krb5_init_context(&pam_context); 410 if (krbret != 0) { 411 PAM_LOG("Error krb5_init_context() failed"); 412 return (PAM_SERVICE_ERR); 413 } 414 415 PAM_LOG("Context initialised"); 416 417 euid = geteuid(); /* Usually 0 */ 418 egid = getegid(); 419 420 PAM_LOG("Got euid, egid: %d %d", euid, egid); 421 422 /* Retrieve the temporary cache */ 423 retval = pam_get_data(pamh, "ccache", &cache_data); 424 if (retval != PAM_SUCCESS) { 425 retval = PAM_CRED_UNAVAIL; 426 goto cleanup3; 427 } 428 krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp); 429 if (krbret != 0) { 430 log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve(\"%s\")", 431 (const char *)cache_data); 432 retval = PAM_SERVICE_ERR; 433 goto cleanup3; 434 } 435 436 /* Get the uid. This should exist. */ 437 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 438 pwd == NULL) { 439 retval = PAM_USER_UNKNOWN; 440 goto cleanup3; 441 } 442 443 PAM_LOG("Done getpwnam_r()"); 444 445 /* Avoid following a symlink as root */ 446 if (setegid(pwd->pw_gid)) { 447 retval = PAM_SERVICE_ERR; 448 goto cleanup3; 449 } 450 if (seteuid(pwd->pw_uid)) { 451 retval = PAM_SERVICE_ERR; 452 goto cleanup3; 453 } 454 455 PAM_LOG("Done setegid() & seteuid()"); 456 457 if (flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED)) { 458 cache_name = getenv("KRB5CCNAME"); 459 if (!cache_name) 460 goto cleanup3; 461 } else { 462 /* Get the cache name */ 463 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 464 if (cache_name == NULL) { 465 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 466 cache_name = cache_name_buf; 467 } 468 469 /* XXX potential overflow */ 470 cache_name_buf2 = p = calloc(PATH_MAX + 16, sizeof(char)); 471 q = cache_name; 472 473 if (p == NULL) { 474 PAM_LOG("Error malloc(): failure"); 475 retval = PAM_BUF_ERR; 476 goto cleanup3; 477 } 478 cache_name = p; 479 480 /* convert %u and %p */ 481 while (*q) { 482 if (*q == '%') { 483 q++; 484 if (*q == 'u') { 485 sprintf(p, "%d", pwd->pw_uid); 486 p += strlen(p); 487 } 488 else if (*q == 'p') { 489 sprintf(p, "%d", getpid()); 490 p += strlen(p); 491 } 492 else { 493 /* Not a special token */ 494 *p++ = '%'; 495 q--; 496 } 497 q++; 498 } 499 else { 500 *p++ = *q++; 501 } 502 } 503 } 504 505 PAM_LOG("Got cache_name: %s", cache_name); 506 507 /* Initialize the new ccache */ 508 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 509 if (krbret != 0) { 510 log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal"); 511 retval = PAM_SERVICE_ERR; 512 goto cleanup3; 513 } 514 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 515 if (krbret != 0) { 516 log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve"); 517 retval = PAM_SERVICE_ERR; 518 goto cleanup2; 519 } 520 521 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 522 if (krbret != 0) { 523 log_krb5(pam_context, krbret, NULL, "krb5_cc_initialize"); 524 retval = PAM_SERVICE_ERR; 525 goto cleanup2; 526 } 527 528 PAM_LOG("Cache initialised"); 529 530 /* Prepare for iteration over creds */ 531 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 532 if (krbret != 0) { 533 log_krb5(pam_context, krbret, NULL, "krb5_cc_start_seq_get"); 534 krb5_cc_destroy(pam_context, ccache_perm); 535 retval = PAM_SERVICE_ERR; 536 goto cleanup2; 537 } 538 539 PAM_LOG("Prepared for iteration"); 540 541 /* Copy the creds (should be two of them) */ 542 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 543 &cursor, &creds)) == 0) { 544 545 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 546 if (krbret != 0) { 547 log_krb5(pam_context, krbret, NULL, 548 "krb5_cc_store_cred"); 549 krb5_cc_destroy(pam_context, ccache_perm); 550 krb5_free_cred_contents(pam_context, &creds); 551 retval = PAM_SERVICE_ERR; 552 goto cleanup2; 553 } 554 555 krb5_free_cred_contents(pam_context, &creds); 556 PAM_LOG("Iteration"); 557 } 558 559 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 560 561 PAM_LOG("Done iterating"); 562 563 if (flags & PAM_ESTABLISH_CRED) { 564 if (strstr(cache_name, "FILE:") == cache_name) { 565 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 566 PAM_LOG("Error chown(): %s", strerror(errno)); 567 krb5_cc_destroy(pam_context, ccache_perm); 568 retval = PAM_SERVICE_ERR; 569 goto cleanup2; 570 } 571 PAM_LOG("Done chown()"); 572 573 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 574 PAM_LOG("Error chmod(): %s", strerror(errno)); 575 krb5_cc_destroy(pam_context, ccache_perm); 576 retval = PAM_SERVICE_ERR; 577 goto cleanup2; 578 } 579 PAM_LOG("Done chmod()"); 580 } 581 } 582 583 krb5_cc_close(pam_context, ccache_perm); 584 585 PAM_LOG("Cache closed"); 586 587 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 588 if (retval != PAM_SUCCESS) { 589 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 590 retval = PAM_SERVICE_ERR; 591 goto cleanup2; 592 } 593 594 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 595 596 cleanup2: 597 krb5_free_principal(pam_context, princ); 598 PAM_LOG("Done cleanup2"); 599 cleanup3: 600 krb5_free_context(pam_context); 601 PAM_LOG("Done cleanup3"); 602 603 seteuid(euid); 604 setegid(egid); 605 606 PAM_LOG("Done seteuid() & setegid()"); 607 608 if (cache_name_buf != NULL) 609 free(cache_name_buf); 610 if (cache_name_buf2 != NULL) 611 free(cache_name_buf2); 612 613 return (retval); 614 } 615 616 /* 617 * account management 618 */ 619 PAM_EXTERN int 620 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 621 int argc __unused, const char *argv[] __unused) 622 { 623 krb5_error_code krbret; 624 krb5_context pam_context; 625 krb5_ccache ccache; 626 krb5_principal princ; 627 int retval; 628 const void *user; 629 const void *ccache_name; 630 631 retval = pam_get_item(pamh, PAM_USER, &user); 632 if (retval != PAM_SUCCESS) 633 return (retval); 634 635 PAM_LOG("Got user: %s", (const char *)user); 636 637 retval = pam_get_data(pamh, "ccache", &ccache_name); 638 if (retval != PAM_SUCCESS) 639 return (PAM_SUCCESS); 640 641 PAM_LOG("Got credentials"); 642 643 krbret = krb5_init_context(&pam_context); 644 if (krbret != 0) { 645 PAM_LOG("Error krb5_init_context() failed"); 646 return (PAM_PERM_DENIED); 647 } 648 649 PAM_LOG("Context initialised"); 650 651 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 652 if (krbret != 0) { 653 log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve(\"%s\")", 654 (const char *)ccache_name); 655 krb5_free_context(pam_context); 656 return (PAM_PERM_DENIED); 657 } 658 659 PAM_LOG("Got ccache %s", (const char *)ccache_name); 660 661 662 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 663 if (krbret != 0) { 664 log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal"); 665 retval = PAM_PERM_DENIED;; 666 goto cleanup; 667 } 668 669 PAM_LOG("Got principal"); 670 671 if (krb5_kuserok(pam_context, princ, (const char *)user)) 672 retval = PAM_SUCCESS; 673 else 674 retval = PAM_PERM_DENIED; 675 krb5_free_principal(pam_context, princ); 676 677 PAM_LOG("Done kuserok()"); 678 679 cleanup: 680 krb5_free_context(pam_context); 681 PAM_LOG("Done cleanup"); 682 683 return (retval); 684 685 } 686 687 /* 688 * password management 689 */ 690 PAM_EXTERN int 691 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 692 int argc __unused, const char *argv[] __unused) 693 { 694 krb5_error_code krbret; 695 krb5_context pam_context; 696 krb5_creds creds; 697 krb5_principal princ; 698 krb5_get_init_creds_opt *opts; 699 krb5_data result_code_string, result_string; 700 int result_code, retval; 701 const char *pass; 702 const void *user; 703 char *princ_name, *passdup; 704 char password_prompt[80]; 705 706 princ_name = NULL; 707 if (flags & PAM_PRELIM_CHECK) { 708 /* Nothing to do here. */ 709 return (PAM_SUCCESS); 710 } 711 712 if (!(flags & PAM_UPDATE_AUTHTOK)) { 713 PAM_LOG("Illegal flags argument"); 714 return (PAM_ABORT); 715 } 716 717 retval = pam_get_item(pamh, PAM_USER, &user); 718 if (retval != PAM_SUCCESS) 719 return (retval); 720 721 PAM_LOG("Got user: %s", (const char *)user); 722 723 krbret = krb5_init_context(&pam_context); 724 if (krbret != 0) { 725 PAM_LOG("Error krb5_init_context() failed"); 726 return (PAM_SERVICE_ERR); 727 } 728 729 PAM_LOG("Context initialised"); 730 731 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 732 if (krbret != 0) { 733 PAM_LOG("Error krb5_init_context() failed"); 734 return (PAM_SERVICE_ERR); 735 } 736 737 krb5_get_init_creds_opt_set_tkt_life(opts, 300); 738 krb5_get_init_creds_opt_set_forwardable(opts, FALSE); 739 krb5_get_init_creds_opt_set_proxiable(opts, FALSE); 740 741 PAM_LOG("Credentials options initialised"); 742 743 /* Get principal name */ 744 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 745 if (krbret != 0) { 746 log_krb5(pam_context, krbret, NULL, "krb5_parse_name"); 747 retval = PAM_USER_UNKNOWN; 748 goto cleanup3; 749 } 750 751 /* Now convert the principal name into something human readable */ 752 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 753 if (krbret != 0) { 754 log_krb5(pam_context, krbret, NULL, "krb5_unparse_name"); 755 retval = PAM_SERVICE_ERR; 756 goto cleanup2; 757 } 758 759 PAM_LOG("Got principal: %s", princ_name); 760 761 /* Get password */ 762 (void) snprintf(password_prompt, sizeof(password_prompt), 763 PASSWORD_PROMPT, princ_name); 764 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt); 765 if (retval != PAM_SUCCESS) 766 goto cleanup2; 767 768 PAM_LOG("Got password"); 769 770 memset(&creds, 0, sizeof(krb5_creds)); 771 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 772 pass, NULL, pamh, 0, "kadmin/changepw", opts); 773 if (krbret != 0) { 774 log_krb5(pam_context, krbret, NULL, 775 "krb5_get_init_creds_password"); 776 retval = PAM_AUTH_ERR; 777 goto cleanup2; 778 } 779 780 PAM_LOG("Credentials established"); 781 782 /* Now get the new password */ 783 for (;;) { 784 retval = pam_get_authtok(pamh, 785 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 786 if (retval != PAM_TRY_AGAIN) 787 break; 788 pam_error(pamh, "Mismatch; try again, EOF to quit."); 789 } 790 if (retval != PAM_SUCCESS) 791 goto cleanup; 792 793 PAM_LOG("Got new password"); 794 795 /* Change it */ 796 if ((passdup = strdup(pass)) == NULL) { 797 retval = PAM_BUF_ERR; 798 goto cleanup; 799 } 800 801 krb5_data_zero(&result_code_string); 802 krb5_data_zero(&result_string); 803 804 krbret = krb5_set_password(pam_context, &creds, passdup, princ, 805 &result_code, &result_code_string, &result_string); 806 free(passdup); 807 if (krbret != 0) { 808 log_krb5(pam_context, krbret, NULL, "Unable to set password"); 809 retval = PAM_AUTHTOK_ERR; 810 goto cleanup; 811 } 812 if (result_code) { 813 pam_info(pamh, "%s%s%.*s", 814 krb5_passwd_result_to_string(pam_context, result_code), 815 result_string.length > 0 ? ": " : "", 816 (int)result_string.length, 817 result_string.length > 0 ? (char *)result_string.data : ""); 818 retval = PAM_AUTHTOK_ERR; 819 } else { 820 PAM_LOG("Password changed"); 821 } 822 823 krb5_data_free(&result_string); 824 krb5_data_free(&result_code_string); 825 826 cleanup: 827 krb5_free_cred_contents(pam_context, &creds); 828 PAM_LOG("Done cleanup"); 829 cleanup2: 830 krb5_free_principal(pam_context, princ); 831 PAM_LOG("Done cleanup2"); 832 cleanup3: 833 if (princ_name) 834 free(princ_name); 835 836 if (opts) 837 krb5_get_init_creds_opt_free(pam_context, opts); 838 839 krb5_free_context(pam_context); 840 841 PAM_LOG("Done cleanup3"); 842 843 return (retval); 844 } 845 846 PAM_MODULE_ENTRY("pam_krb5"); 847 848 static void 849 log_krb5(krb5_context ctx, krb5_error_code err, 850 struct syslog_data *data, const char *fmt, ...) 851 { 852 char b1[1024], b2[1024]; 853 const char *errtxt; 854 va_list ap; 855 856 va_start(ap, fmt); 857 vsnprintf(b1, sizeof(b1), fmt, ap); 858 va_end(ap); 859 if (ctx) 860 errtxt = krb5_get_error_message(ctx, err); 861 else 862 errtxt = NULL; 863 if (errtxt != NULL) { 864 snprintf(b2, sizeof(b2), "%s", errtxt); 865 krb5_free_error_message(ctx, errtxt); 866 } else { 867 snprintf(b2, sizeof(b2), "unknown %d", (int)err); 868 } 869 if (data) 870 syslog_r(LOG_DEBUG, data, "%s (%s)", b1, b2); 871 else 872 PAM_LOG("%s (%s)", b1, b2); 873 } 874 875 /* 876 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 877 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 878 * for Debian. 879 * 880 * Verify the Kerberos ticket-granting ticket just retrieved for the 881 * user. If the Kerberos server doesn't respond, assume the user is 882 * trying to fake us out (since we DID just get a TGT from what is 883 * supposedly our KDC). If the host/<host> service is unknown (i.e., 884 * the local keytab doesn't have it), and we cannot find another 885 * service we do have, let her in. 886 * 887 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 888 */ 889 /* ARGSUSED */ 890 static int 891 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 892 char *pam_service, int debug) 893 { 894 krb5_error_code retval; 895 krb5_principal princ; 896 krb5_keyblock *keyblock; 897 krb5_data packet; 898 krb5_auth_context auth_context = NULL; 899 char phost[BUFSIZ]; 900 const char *services[3], **service; 901 struct syslog_data data = SYSLOG_DATA_INIT; 902 903 packet.data = 0; 904 905 if (debug) 906 openlog_r("pam_krb5", LOG_PID, LOG_AUTHPRIV, &data); 907 908 /* If possible we want to try and verify the ticket we have 909 * received against a keytab. We will try multiple service 910 * principals, including at least the host principal and the PAM 911 * service principal. The host principal is preferred because access 912 * to that key is generally sufficient to compromise root, while the 913 * service key for this PAM service may be less carefully guarded. 914 * It is important to check the keytab first before the KDC so we do 915 * not get spoofed by a fake KDC. 916 */ 917 services[0] = "host"; 918 services[1] = pam_service; 919 services[2] = NULL; 920 keyblock = 0; 921 retval = -1; 922 for (service = &services[0]; *service != NULL; service++) { 923 retval = krb5_sname_to_principal(context, NULL, *service, 924 KRB5_NT_SRV_HST, &princ); 925 if (retval != 0 && debug) 926 log_krb5(context, retval, &data, 927 "pam_krb5: verify_krb_v5_tgt: " 928 "krb5_sname_to_principal"); 929 if (retval != 0) 930 return -1; 931 932 /* Extract the name directly. */ 933 strncpy(phost, compat_princ_component(context, princ, 1), 934 BUFSIZ); 935 phost[BUFSIZ - 1] = '\0'; 936 937 /* 938 * Do we have service/<host> keys? 939 * (use default/configured keytab, kvno IGNORE_VNO to get the 940 * first match, and ignore enctype.) 941 */ 942 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 943 &keyblock); 944 if (retval != 0) 945 continue; 946 break; 947 } 948 if (retval != 0) { /* failed to find key */ 949 /* Keytab or service key does not exist */ 950 if (debug) 951 log_krb5(context, retval, &data, 952 "pam_krb5: verify_krb_v5_tgt: " 953 "krb5_kt_read_service_key"); 954 retval = 0; 955 goto cleanup; 956 } 957 if (keyblock) 958 krb5_free_keyblock(context, keyblock); 959 960 /* Talk to the kdc and construct the ticket. */ 961 auth_context = NULL; 962 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 963 NULL, ccache, &packet); 964 if (auth_context) { 965 krb5_auth_con_free(context, auth_context); 966 auth_context = NULL; /* setup for rd_req */ 967 } 968 if (retval) { 969 if (debug) 970 log_krb5(context, retval, &data, 971 "pam_krb5: verify_krb_v5_tgt: " 972 "krb5_mk_req"); 973 retval = -1; 974 goto cleanup; 975 } 976 977 /* Try to use the ticket. */ 978 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 979 NULL, NULL); 980 if (retval) { 981 if (debug) 982 log_krb5(context, retval, &data, 983 "pam_krb5: verify_krb_v5_tgt: " 984 "krb5_rd_req"); 985 retval = -1; 986 } 987 else 988 retval = 1; 989 990 cleanup: 991 if (debug) 992 closelog_r(&data); 993 if (packet.data) 994 compat_free_data_contents(context, &packet); 995 if (auth_context) { 996 krb5_auth_con_free(context, auth_context); 997 auth_context = NULL; /* setup for rd_req */ 998 } 999 krb5_free_principal(context, princ); 1000 return retval; 1001 } 1002 1003 /* Free the memory for cache_name. Called by pam_end() */ 1004 /* ARGSUSED */ 1005 static void 1006 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 1007 { 1008 krb5_context pam_context; 1009 krb5_ccache ccache; 1010 krb5_error_code krbret; 1011 1012 if (krb5_init_context(&pam_context)) 1013 return; 1014 1015 krbret = krb5_cc_resolve(pam_context, data, &ccache); 1016 if (krbret == 0) 1017 krb5_cc_destroy(pam_context, ccache); 1018 krb5_free_context(pam_context); 1019 free(data); 1020 } 1021 1022 #ifdef COMPAT_HEIMDAL 1023 #ifdef COMPAT_MIT 1024 #error This cannot be MIT and Heimdal compatible! 1025 #endif 1026 #endif 1027 1028 #ifndef COMPAT_HEIMDAL 1029 #ifndef COMPAT_MIT 1030 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 1031 #endif 1032 #endif 1033 1034 #ifdef COMPAT_HEIMDAL 1035 /* ARGSUSED */ 1036 static const char * 1037 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 1038 { 1039 return princ->name.name_string.val[n]; 1040 } 1041 1042 /* ARGSUSED */ 1043 static void 1044 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 1045 { 1046 krb5_xfree(data->data); 1047 } 1048 #endif 1049 1050 #ifdef COMPAT_MIT 1051 static const char * 1052 compat_princ_component(krb5_context context, krb5_principal princ, int n) 1053 { 1054 return krb5_princ_component(context, princ, n)->data; 1055 } 1056 1057 static void 1058 compat_free_data_contents(krb5_context context, krb5_data * data) 1059 { 1060 krb5_free_data_contents(context, data); 1061 } 1062 #endif 1063
Indexes created Tue Sep 30 11:09:46 GMT 2025