pam_krb5.c revision 1.26.26.1
1 /* $NetBSD: pam_krb5.c,v 1.26.26.1 2020/04/08 14:07:15 martin 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 1.26.26.1 2020/04/08 14:07:15 martin 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 size_t len = PATH_MAX + 16; 463 /* Get the cache name */ 464 cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE); 465 if (cache_name == NULL) { 466 asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid); 467 cache_name = cache_name_buf; 468 } 469 470 cache_name_buf2 = p = calloc(len, 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 int l; 483 if (*q == '%') { 484 q++; 485 if (*q == 'u') { 486 l = snprintf(p, len, "%d", pwd->pw_uid); 487 } 488 else if (*q == 'p') { 489 l = snprintf(p, len, "%d", getpid()); 490 } 491 else { 492 /* Not a special token */ 493 if (!len) 494 goto truncated; 495 *p = '%'; 496 l = 1; 497 q--; 498 } 499 if ((size_t)l > len) { 500 truncated: PAM_LOG("string truncation failure"); 501 retval = PAM_BUF_ERR; 502 goto cleanup3; 503 } 504 q++; 505 } 506 else { 507 if (!len) 508 goto truncated; 509 *p = *q++; 510 l = 1; 511 } 512 p += l; 513 len -= (size_t)l; 514 } 515 if (!len) 516 goto truncated; 517 *p = '\0'; 518 } 519 520 PAM_LOG("Got cache_name: %s", cache_name); 521 522 /* Initialize the new ccache */ 523 krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ); 524 if (krbret != 0) { 525 log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal"); 526 retval = PAM_SERVICE_ERR; 527 goto cleanup3; 528 } 529 krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm); 530 if (krbret != 0) { 531 log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve"); 532 retval = PAM_SERVICE_ERR; 533 goto cleanup2; 534 } 535 536 krbret = krb5_cc_initialize(pam_context, ccache_perm, princ); 537 if (krbret != 0) { 538 log_krb5(pam_context, krbret, NULL, "krb5_cc_initialize"); 539 retval = PAM_SERVICE_ERR; 540 goto cleanup2; 541 } 542 543 PAM_LOG("Cache initialised"); 544 545 /* Prepare for iteration over creds */ 546 krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor); 547 if (krbret != 0) { 548 log_krb5(pam_context, krbret, NULL, "krb5_cc_start_seq_get"); 549 krb5_cc_destroy(pam_context, ccache_perm); 550 retval = PAM_SERVICE_ERR; 551 goto cleanup2; 552 } 553 554 PAM_LOG("Prepared for iteration"); 555 556 /* Copy the creds (should be two of them) */ 557 while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp, 558 &cursor, &creds)) == 0) { 559 560 krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds); 561 if (krbret != 0) { 562 log_krb5(pam_context, krbret, NULL, 563 "krb5_cc_store_cred"); 564 krb5_cc_destroy(pam_context, ccache_perm); 565 krb5_free_cred_contents(pam_context, &creds); 566 retval = PAM_SERVICE_ERR; 567 goto cleanup2; 568 } 569 570 krb5_free_cred_contents(pam_context, &creds); 571 PAM_LOG("Iteration"); 572 } 573 574 krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor); 575 576 PAM_LOG("Done iterating"); 577 578 if (flags & PAM_ESTABLISH_CRED) { 579 if (strstr(cache_name, "FILE:") == cache_name) { 580 if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) { 581 PAM_LOG("Error chown(): %s", strerror(errno)); 582 krb5_cc_destroy(pam_context, ccache_perm); 583 retval = PAM_SERVICE_ERR; 584 goto cleanup2; 585 } 586 PAM_LOG("Done chown()"); 587 588 if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) { 589 PAM_LOG("Error chmod(): %s", strerror(errno)); 590 krb5_cc_destroy(pam_context, ccache_perm); 591 retval = PAM_SERVICE_ERR; 592 goto cleanup2; 593 } 594 PAM_LOG("Done chmod()"); 595 } 596 } 597 598 krb5_cc_close(pam_context, ccache_perm); 599 600 PAM_LOG("Cache closed"); 601 602 retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1); 603 if (retval != PAM_SUCCESS) { 604 PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval)); 605 retval = PAM_SERVICE_ERR; 606 goto cleanup2; 607 } 608 609 PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name); 610 611 cleanup2: 612 krb5_free_principal(pam_context, princ); 613 PAM_LOG("Done cleanup2"); 614 cleanup3: 615 krb5_free_context(pam_context); 616 PAM_LOG("Done cleanup3"); 617 618 seteuid(euid); 619 setegid(egid); 620 621 PAM_LOG("Done seteuid() & setegid()"); 622 623 if (cache_name_buf != NULL) 624 free(cache_name_buf); 625 if (cache_name_buf2 != NULL) 626 free(cache_name_buf2); 627 628 return (retval); 629 } 630 631 /* 632 * account management 633 */ 634 PAM_EXTERN int 635 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused, 636 int argc __unused, const char *argv[] __unused) 637 { 638 krb5_error_code krbret; 639 krb5_context pam_context; 640 krb5_ccache ccache; 641 krb5_principal princ; 642 int retval; 643 const void *user; 644 const void *ccache_name; 645 646 retval = pam_get_item(pamh, PAM_USER, &user); 647 if (retval != PAM_SUCCESS) 648 return (retval); 649 650 PAM_LOG("Got user: %s", (const char *)user); 651 652 retval = pam_get_data(pamh, "ccache", &ccache_name); 653 if (retval != PAM_SUCCESS) 654 return (PAM_SUCCESS); 655 656 PAM_LOG("Got credentials"); 657 658 krbret = krb5_init_context(&pam_context); 659 if (krbret != 0) { 660 PAM_LOG("Error krb5_init_context() failed"); 661 return (PAM_PERM_DENIED); 662 } 663 664 PAM_LOG("Context initialised"); 665 666 krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache); 667 if (krbret != 0) { 668 log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve(\"%s\")", 669 (const char *)ccache_name); 670 krb5_free_context(pam_context); 671 return (PAM_PERM_DENIED); 672 } 673 674 PAM_LOG("Got ccache %s", (const char *)ccache_name); 675 676 677 krbret = krb5_cc_get_principal(pam_context, ccache, &princ); 678 if (krbret != 0) { 679 log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal"); 680 retval = PAM_PERM_DENIED;; 681 goto cleanup; 682 } 683 684 PAM_LOG("Got principal"); 685 686 if (krb5_kuserok(pam_context, princ, (const char *)user)) 687 retval = PAM_SUCCESS; 688 else 689 retval = PAM_PERM_DENIED; 690 krb5_free_principal(pam_context, princ); 691 692 PAM_LOG("Done kuserok()"); 693 694 cleanup: 695 krb5_free_context(pam_context); 696 PAM_LOG("Done cleanup"); 697 698 return (retval); 699 700 } 701 702 /* 703 * password management 704 */ 705 PAM_EXTERN int 706 pam_sm_chauthtok(pam_handle_t *pamh, int flags, 707 int argc __unused, const char *argv[] __unused) 708 { 709 krb5_error_code krbret; 710 krb5_context pam_context; 711 krb5_creds creds; 712 krb5_principal princ; 713 krb5_get_init_creds_opt *opts; 714 krb5_data result_code_string, result_string; 715 int result_code, retval; 716 const char *pass; 717 const void *user; 718 char *princ_name, *passdup; 719 char password_prompt[80]; 720 721 princ_name = NULL; 722 if (flags & PAM_PRELIM_CHECK) { 723 /* Nothing to do here. */ 724 return (PAM_SUCCESS); 725 } 726 727 if (!(flags & PAM_UPDATE_AUTHTOK)) { 728 PAM_LOG("Illegal flags argument"); 729 return (PAM_ABORT); 730 } 731 732 retval = pam_get_item(pamh, PAM_USER, &user); 733 if (retval != PAM_SUCCESS) 734 return (retval); 735 736 PAM_LOG("Got user: %s", (const char *)user); 737 738 krbret = krb5_init_context(&pam_context); 739 if (krbret != 0) { 740 PAM_LOG("Error krb5_init_context() failed"); 741 return (PAM_SERVICE_ERR); 742 } 743 744 PAM_LOG("Context initialised"); 745 746 krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts); 747 if (krbret != 0) { 748 PAM_LOG("Error krb5_init_context() failed"); 749 return (PAM_SERVICE_ERR); 750 } 751 752 krb5_get_init_creds_opt_set_tkt_life(opts, 300); 753 krb5_get_init_creds_opt_set_forwardable(opts, FALSE); 754 krb5_get_init_creds_opt_set_proxiable(opts, FALSE); 755 756 PAM_LOG("Credentials options initialised"); 757 758 /* Get principal name */ 759 krbret = krb5_parse_name(pam_context, (const char *)user, &princ); 760 if (krbret != 0) { 761 log_krb5(pam_context, krbret, NULL, "krb5_parse_name"); 762 retval = PAM_USER_UNKNOWN; 763 goto cleanup3; 764 } 765 766 /* Now convert the principal name into something human readable */ 767 krbret = krb5_unparse_name(pam_context, princ, &princ_name); 768 if (krbret != 0) { 769 log_krb5(pam_context, krbret, NULL, "krb5_unparse_name"); 770 retval = PAM_SERVICE_ERR; 771 goto cleanup2; 772 } 773 774 PAM_LOG("Got principal: %s", princ_name); 775 776 /* Get password */ 777 (void) snprintf(password_prompt, sizeof(password_prompt), 778 PASSWORD_PROMPT, princ_name); 779 retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt); 780 if (retval != PAM_SUCCESS) 781 goto cleanup2; 782 783 PAM_LOG("Got password"); 784 785 memset(&creds, 0, sizeof(krb5_creds)); 786 krbret = krb5_get_init_creds_password(pam_context, &creds, princ, 787 pass, NULL, pamh, 0, "kadmin/changepw", opts); 788 if (krbret != 0) { 789 log_krb5(pam_context, krbret, NULL, 790 "krb5_get_init_creds_password"); 791 retval = PAM_AUTH_ERR; 792 goto cleanup2; 793 } 794 795 PAM_LOG("Credentials established"); 796 797 /* Now get the new password */ 798 for (;;) { 799 retval = pam_get_authtok(pamh, 800 PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT); 801 if (retval != PAM_TRY_AGAIN) 802 break; 803 pam_error(pamh, "Mismatch; try again, EOF to quit."); 804 } 805 if (retval != PAM_SUCCESS) 806 goto cleanup; 807 808 PAM_LOG("Got new password"); 809 810 /* Change it */ 811 if ((passdup = strdup(pass)) == NULL) { 812 retval = PAM_BUF_ERR; 813 goto cleanup; 814 } 815 816 krb5_data_zero(&result_code_string); 817 krb5_data_zero(&result_string); 818 819 krbret = krb5_set_password(pam_context, &creds, passdup, princ, 820 &result_code, &result_code_string, &result_string); 821 free(passdup); 822 if (krbret != 0) { 823 log_krb5(pam_context, krbret, NULL, "Unable to set password"); 824 retval = PAM_AUTHTOK_ERR; 825 goto cleanup; 826 } 827 if (result_code) { 828 pam_info(pamh, "%s%s%.*s", 829 krb5_passwd_result_to_string(pam_context, result_code), 830 result_string.length > 0 ? ": " : "", 831 (int)result_string.length, 832 result_string.length > 0 ? (char *)result_string.data : ""); 833 retval = PAM_AUTHTOK_ERR; 834 } else { 835 PAM_LOG("Password changed"); 836 } 837 838 krb5_data_free(&result_string); 839 krb5_data_free(&result_code_string); 840 841 cleanup: 842 krb5_free_cred_contents(pam_context, &creds); 843 PAM_LOG("Done cleanup"); 844 cleanup2: 845 krb5_free_principal(pam_context, princ); 846 PAM_LOG("Done cleanup2"); 847 cleanup3: 848 if (princ_name) 849 free(princ_name); 850 851 if (opts) 852 krb5_get_init_creds_opt_free(pam_context, opts); 853 854 krb5_free_context(pam_context); 855 856 PAM_LOG("Done cleanup3"); 857 858 return (retval); 859 } 860 861 PAM_MODULE_ENTRY("pam_krb5"); 862 863 static void 864 log_krb5(krb5_context ctx, krb5_error_code err, 865 struct syslog_data *data, const char *fmt, ...) 866 { 867 char b1[1024], b2[1024]; 868 const char *errtxt; 869 va_list ap; 870 871 va_start(ap, fmt); 872 vsnprintf(b1, sizeof(b1), fmt, ap); 873 va_end(ap); 874 if (ctx) 875 errtxt = krb5_get_error_message(ctx, err); 876 else 877 errtxt = NULL; 878 if (errtxt != NULL) { 879 snprintf(b2, sizeof(b2), "%s", errtxt); 880 krb5_free_error_message(ctx, errtxt); 881 } else { 882 snprintf(b2, sizeof(b2), "unknown %d", (int)err); 883 } 884 if (data) 885 syslog_r(LOG_DEBUG, data, "%s (%s)", b1, b2); 886 else 887 PAM_LOG("%s (%s)", b1, b2); 888 } 889 890 /* 891 * This routine with some modification is from the MIT V5B6 appl/bsd/login.c 892 * Modified by Sam Hartman <hartmans (at) mit.edu> to support PAM services 893 * for Debian. 894 * 895 * Verify the Kerberos ticket-granting ticket just retrieved for the 896 * user. If the Kerberos server doesn't respond, assume the user is 897 * trying to fake us out (since we DID just get a TGT from what is 898 * supposedly our KDC). If the host/<host> service is unknown (i.e., 899 * the local keytab doesn't have it), and we cannot find another 900 * service we do have, let her in. 901 * 902 * Returns 1 for confirmation, -1 for failure, 0 for uncertainty. 903 */ 904 /* ARGSUSED */ 905 static int 906 verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache, 907 char *pam_service, int debug) 908 { 909 krb5_error_code retval; 910 krb5_principal princ; 911 krb5_keyblock *keyblock; 912 krb5_data packet; 913 krb5_auth_context auth_context = NULL; 914 char phost[BUFSIZ]; 915 const char *services[3], **service; 916 struct syslog_data data = SYSLOG_DATA_INIT; 917 918 packet.data = 0; 919 920 if (debug) 921 openlog_r("pam_krb5", LOG_PID, LOG_AUTHPRIV, &data); 922 923 /* If possible we want to try and verify the ticket we have 924 * received against a keytab. We will try multiple service 925 * principals, including at least the host principal and the PAM 926 * service principal. The host principal is preferred because access 927 * to that key is generally sufficient to compromise root, while the 928 * service key for this PAM service may be less carefully guarded. 929 * It is important to check the keytab first before the KDC so we do 930 * not get spoofed by a fake KDC. 931 */ 932 services[0] = "host"; 933 services[1] = pam_service; 934 services[2] = NULL; 935 keyblock = 0; 936 retval = -1; 937 for (service = &services[0]; *service != NULL; service++) { 938 retval = krb5_sname_to_principal(context, NULL, *service, 939 KRB5_NT_SRV_HST, &princ); 940 if (retval != 0 && debug) 941 log_krb5(context, retval, &data, 942 "pam_krb5: verify_krb_v5_tgt: " 943 "krb5_sname_to_principal"); 944 if (retval != 0) 945 return -1; 946 947 /* Extract the name directly. */ 948 strncpy(phost, compat_princ_component(context, princ, 1), 949 BUFSIZ); 950 phost[BUFSIZ - 1] = '\0'; 951 952 /* 953 * Do we have service/<host> keys? 954 * (use default/configured keytab, kvno IGNORE_VNO to get the 955 * first match, and ignore enctype.) 956 */ 957 retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0, 958 &keyblock); 959 if (retval != 0) 960 continue; 961 break; 962 } 963 if (retval != 0) { /* failed to find key */ 964 /* Keytab or service key does not exist */ 965 if (debug) 966 log_krb5(context, retval, &data, 967 "pam_krb5: verify_krb_v5_tgt: " 968 "krb5_kt_read_service_key"); 969 retval = 0; 970 goto cleanup; 971 } 972 if (keyblock) 973 krb5_free_keyblock(context, keyblock); 974 975 /* Talk to the kdc and construct the ticket. */ 976 auth_context = NULL; 977 retval = krb5_mk_req(context, &auth_context, 0, *service, phost, 978 NULL, ccache, &packet); 979 if (auth_context) { 980 krb5_auth_con_free(context, auth_context); 981 auth_context = NULL; /* setup for rd_req */ 982 } 983 if (retval) { 984 if (debug) 985 log_krb5(context, retval, &data, 986 "pam_krb5: verify_krb_v5_tgt: " 987 "krb5_mk_req"); 988 retval = -1; 989 goto cleanup; 990 } 991 992 /* Try to use the ticket. */ 993 retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL, 994 NULL, NULL); 995 if (retval) { 996 if (debug) 997 log_krb5(context, retval, &data, 998 "pam_krb5: verify_krb_v5_tgt: " 999 "krb5_rd_req"); 1000 retval = -1; 1001 } 1002 else 1003 retval = 1; 1004 1005 cleanup: 1006 if (debug) 1007 closelog_r(&data); 1008 if (packet.data) 1009 compat_free_data_contents(context, &packet); 1010 if (auth_context) { 1011 krb5_auth_con_free(context, auth_context); 1012 auth_context = NULL; /* setup for rd_req */ 1013 } 1014 krb5_free_principal(context, princ); 1015 return retval; 1016 } 1017 1018 /* Free the memory for cache_name. Called by pam_end() */ 1019 /* ARGSUSED */ 1020 static void 1021 cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused) 1022 { 1023 krb5_context pam_context; 1024 krb5_ccache ccache; 1025 krb5_error_code krbret; 1026 1027 if (krb5_init_context(&pam_context)) 1028 return; 1029 1030 krbret = krb5_cc_resolve(pam_context, data, &ccache); 1031 if (krbret == 0) 1032 krb5_cc_destroy(pam_context, ccache); 1033 krb5_free_context(pam_context); 1034 free(data); 1035 } 1036 1037 #ifdef COMPAT_HEIMDAL 1038 #ifdef COMPAT_MIT 1039 #error This cannot be MIT and Heimdal compatible! 1040 #endif 1041 #endif 1042 1043 #ifndef COMPAT_HEIMDAL 1044 #ifndef COMPAT_MIT 1045 #error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified! 1046 #endif 1047 #endif 1048 1049 #ifdef COMPAT_HEIMDAL 1050 /* ARGSUSED */ 1051 static const char * 1052 compat_princ_component(krb5_context context __unused, krb5_principal princ, int n) 1053 { 1054 return princ->name.name_string.val[n]; 1055 } 1056 1057 /* ARGSUSED */ 1058 static void 1059 compat_free_data_contents(krb5_context context __unused, krb5_data * data) 1060 { 1061 krb5_xfree(data->data); 1062 } 1063 #endif 1064 1065 #ifdef COMPAT_MIT 1066 static const char * 1067 compat_princ_component(krb5_context context, krb5_principal princ, int n) 1068 { 1069 return krb5_princ_component(context, princ, n)->data; 1070 } 1071 1072 static void 1073 compat_free_data_contents(krb5_context context, krb5_data * data) 1074 { 1075 krb5_free_data_contents(context, data); 1076 } 1077 #endif 1078
Indexes created Fri Oct 03 02:09:57 GMT 2025