1 /* $NetBSD: transited.c,v 1.3 2023/06/19 21:41:45 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1997 - 2001, 2003 Kungliga Tekniska Hgskolan 5 * (Royal Institute of Technology, Stockholm, Sweden). 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * 3. Neither the name of the Institute nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include "krb5_locl.h" 37 38 /* this is an attempt at one of the most horrible `compression' 39 schemes that has ever been invented; it's so amazingly brain-dead 40 that words can not describe it, and all this just to save a few 41 silly bytes */ 42 43 struct tr_realm { 44 char *realm; 45 unsigned leading_space:1; 46 unsigned leading_slash:1; 47 unsigned trailing_dot:1; 48 struct tr_realm *next; 49 }; 50 51 static void 52 free_realms(struct tr_realm *r) 53 { 54 struct tr_realm *p; 55 while(r){ 56 p = r; 57 r = r->next; 58 free(p->realm); 59 free(p); 60 } 61 } 62 63 static int 64 make_path(krb5_context context, struct tr_realm *r, 65 const char *from, const char *to) 66 { 67 struct tr_realm *tmp; 68 const char *p; 69 70 if(strlen(from) < strlen(to)){ 71 const char *str; 72 str = from; 73 from = to; 74 to = str; 75 } 76 77 if(strcmp(from + strlen(from) - strlen(to), to) == 0){ 78 p = from; 79 while(1){ 80 p = strchr(p, '.'); 81 if(p == NULL) { 82 krb5_clear_error_message (context); 83 return KRB5KDC_ERR_POLICY; 84 } 85 p++; 86 if(strcmp(p, to) == 0) 87 break; 88 tmp = calloc(1, sizeof(*tmp)); 89 if(tmp == NULL) 90 return krb5_enomem(context); 91 tmp->next = r->next; 92 r->next = tmp; 93 tmp->realm = strdup(p); 94 if(tmp->realm == NULL){ 95 r->next = tmp->next; 96 free(tmp); 97 return krb5_enomem(context); 98 } 99 } 100 }else if(strncmp(from, to, strlen(to)) == 0){ 101 p = from + strlen(from); 102 while(1){ 103 while(p >= from && *p != '/') p--; 104 if(p == from) 105 return KRB5KDC_ERR_POLICY; 106 107 if(strncmp(to, from, p - from) == 0) 108 break; 109 tmp = calloc(1, sizeof(*tmp)); 110 if(tmp == NULL) 111 return krb5_enomem(context); 112 tmp->next = r->next; 113 r->next = tmp; 114 tmp->realm = malloc(p - from + 1); 115 if(tmp->realm == NULL){ 116 r->next = tmp->next; 117 free(tmp); 118 return krb5_enomem(context); 119 } 120 memcpy(tmp->realm, from, p - from); 121 tmp->realm[p - from] = '\0'; 122 p--; 123 } 124 } else { 125 krb5_clear_error_message (context); 126 return KRB5KDC_ERR_POLICY; 127 } 128 129 return 0; 130 } 131 132 static int 133 make_paths(krb5_context context, 134 struct tr_realm *realms, const char *client_realm, 135 const char *server_realm) 136 { 137 struct tr_realm *r; 138 int ret; 139 const char *prev_realm = client_realm; 140 const char *next_realm = NULL; 141 for(r = realms; r; r = r->next){ 142 /* it *might* be that you can have more than one empty 143 component in a row, at least that's how I interpret the 144 "," exception in 1510 */ 145 if(r->realm[0] == '\0'){ 146 while(r->next && r->next->realm[0] == '\0') 147 r = r->next; 148 if(r->next) 149 next_realm = r->next->realm; 150 else 151 next_realm = server_realm; 152 ret = make_path(context, r, prev_realm, next_realm); 153 if(ret){ 154 free_realms(realms); 155 return ret; 156 } 157 } 158 prev_realm = r->realm; 159 } 160 return 0; 161 } 162 163 static int 164 expand_realms(krb5_context context, 165 struct tr_realm *realms, const char *client_realm) 166 { 167 struct tr_realm *r; 168 const char *prev_realm = NULL; 169 for(r = realms; r; r = r->next){ 170 if(r->trailing_dot){ 171 char *tmp; 172 size_t len; 173 174 if(prev_realm == NULL) 175 prev_realm = client_realm; 176 177 len = strlen(r->realm) + strlen(prev_realm) + 1; 178 179 tmp = realloc(r->realm, len); 180 if(tmp == NULL){ 181 free_realms(realms); 182 return krb5_enomem(context); 183 } 184 r->realm = tmp; 185 strlcat(r->realm, prev_realm, len); 186 }else if(r->leading_slash && !r->leading_space && prev_realm){ 187 /* yet another exception: if you use x500-names, the 188 leading realm doesn't have to be "quoted" with a space */ 189 char *tmp; 190 size_t len = strlen(r->realm) + strlen(prev_realm) + 1; 191 192 tmp = malloc(len); 193 if(tmp == NULL){ 194 free_realms(realms); 195 return krb5_enomem(context); 196 } 197 strlcpy(tmp, prev_realm, len); 198 strlcat(tmp, r->realm, len); 199 free(r->realm); 200 r->realm = tmp; 201 } 202 prev_realm = r->realm; 203 } 204 return 0; 205 } 206 207 static struct tr_realm * 208 make_realm(char *realm) 209 { 210 struct tr_realm *r; 211 char *p, *q; 212 int quote = 0; 213 r = calloc(1, sizeof(*r)); 214 if(r == NULL){ 215 free(realm); 216 return NULL; 217 } 218 r->realm = realm; 219 for(p = q = r->realm; *p; p++){ 220 if(p == r->realm && *p == ' '){ 221 r->leading_space = 1; 222 continue; 223 } 224 if(q == r->realm && *p == '/') 225 r->leading_slash = 1; 226 if(quote){ 227 *q++ = *p; 228 quote = 0; 229 continue; 230 } 231 if(*p == '\\'){ 232 quote = 1; 233 continue; 234 } 235 if(p[0] == '.' && p[1] == '\0') 236 r->trailing_dot = 1; 237 *q++ = *p; 238 } 239 *q = '\0'; 240 return r; 241 } 242 243 static struct tr_realm* 244 append_realm(struct tr_realm *head, struct tr_realm *r) 245 { 246 struct tr_realm *p; 247 if(head == NULL){ 248 r->next = NULL; 249 return r; 250 } 251 p = head; 252 while(p->next) p = p->next; 253 p->next = r; 254 return head; 255 } 256 257 static int 258 decode_realms(krb5_context context, 259 const char *tr, int length, struct tr_realm **realms) 260 { 261 struct tr_realm *r = NULL; 262 263 char *tmp; 264 int quote = 0; 265 const char *start = tr; 266 int i; 267 268 for(i = 0; i < length; i++){ 269 if(quote){ 270 quote = 0; 271 continue; 272 } 273 if(tr[i] == '\\'){ 274 quote = 1; 275 continue; 276 } 277 if(tr[i] == ','){ 278 tmp = malloc(tr + i - start + 1); 279 if(tmp == NULL) 280 return krb5_enomem(context); 281 memcpy(tmp, start, tr + i - start); 282 tmp[tr + i - start] = '\0'; 283 r = make_realm(tmp); 284 if(r == NULL){ 285 free_realms(*realms); 286 *realms = NULL; 287 return krb5_enomem(context); 288 } 289 *realms = append_realm(*realms, r); 290 start = tr + i + 1; 291 } 292 } 293 tmp = malloc(tr + i - start + 1); 294 if(tmp == NULL){ 295 free_realms(*realms); 296 *realms = NULL; 297 return krb5_enomem(context); 298 } 299 memcpy(tmp, start, tr + i - start); 300 tmp[tr + i - start] = '\0'; 301 r = make_realm(tmp); 302 if(r == NULL){ 303 free_realms(*realms); 304 *realms = NULL; 305 return krb5_enomem(context); 306 } 307 *realms = append_realm(*realms, r); 308 309 return 0; 310 } 311 312 313 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 314 krb5_domain_x500_decode(krb5_context context, 315 krb5_data tr, char ***realms, unsigned int *num_realms, 316 const char *client_realm, const char *server_realm) 317 { 318 struct tr_realm *r = NULL; 319 struct tr_realm *p, **q; 320 int ret; 321 322 if(tr.length == 0) { 323 *realms = NULL; 324 *num_realms = 0; 325 return 0; 326 } 327 328 /* split string in components */ 329 ret = decode_realms(context, tr.data, tr.length, &r); 330 if(ret) 331 return ret; 332 333 /* apply prefix rule */ 334 ret = expand_realms(context, r, client_realm); 335 if(ret) 336 return ret; 337 338 ret = make_paths(context, r, client_realm, server_realm); 339 if(ret) 340 return ret; 341 342 /* remove empty components and count realms */ 343 *num_realms = 0; 344 for(q = &r; *q; ){ 345 if((*q)->realm[0] == '\0'){ 346 p = *q; 347 *q = (*q)->next; 348 free(p->realm); 349 free(p); 350 }else{ 351 q = &(*q)->next; 352 (*num_realms)++; 353 } 354 } 355 if (*num_realms + 1 > UINT_MAX/sizeof(**realms)) 356 return ERANGE; 357 358 { 359 char **R; 360 R = malloc((*num_realms + 1) * sizeof(*R)); 361 if (R == NULL) 362 return krb5_enomem(context); 363 *realms = R; 364 while(r){ 365 *R++ = r->realm; 366 p = r->next; 367 free(r); 368 r = p; 369 } 370 } 371 return 0; 372 } 373 374 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 375 krb5_domain_x500_encode(char **realms, unsigned int num_realms, 376 krb5_data *encoding) 377 { 378 char *s = NULL; 379 int len = 0; 380 unsigned int i; 381 krb5_data_zero(encoding); 382 if (num_realms == 0) 383 return 0; 384 for(i = 0; i < num_realms; i++){ 385 len += strlen(realms[i]); 386 if(realms[i][0] == '/') 387 len++; 388 } 389 len += num_realms - 1; 390 s = malloc(len + 1); 391 if (s == NULL) 392 return ENOMEM; 393 *s = '\0'; 394 for(i = 0; i < num_realms; i++){ 395 if(i) 396 strlcat(s, ",", len + 1); 397 if(realms[i][0] == '/') 398 strlcat(s, " ", len + 1); 399 strlcat(s, realms[i], len + 1); 400 } 401 encoding->data = s; 402 encoding->length = strlen(s); 403 return 0; 404 } 405 406 KRB5_LIB_FUNCTION void KRB5_LIB_CALL 407 _krb5_free_capath(krb5_context context, char **capath) 408 { 409 char **s; 410 411 for (s = capath; s && *s; ++s) 412 free(*s); 413 free(capath); 414 } 415 416 struct hier_iter { 417 const char *local_realm; 418 const char *server_realm; 419 const char *lr; /* Pointer into tail of local realm */ 420 const char *sr; /* Pointer into tail of server realm */ 421 size_t llen; /* Length of local_realm */ 422 size_t slen; /* Length of server_realm */ 423 size_t len; /* Length of common suffix */ 424 size_t num; /* Path element count */ 425 }; 426 427 /* 428 * Step up from local_realm to common suffix, or else down to server_realm. 429 */ 430 static const char * 431 hier_next(struct hier_iter *state) 432 { 433 const char *lr = state->lr; 434 const char *sr = state->sr; 435 const char *lsuffix = state->local_realm + state->llen - state->len; 436 const char *server_realm = state->server_realm; 437 438 if (lr != NULL) { 439 while (lr < lsuffix) 440 if (*lr++ == '.') 441 return state->lr = lr; 442 state->lr = NULL; 443 } 444 if (sr != NULL) { 445 while (--sr >= server_realm) 446 if (sr == server_realm || sr[-1] == '.') 447 return state->sr = sr; 448 state->sr = NULL; 449 } 450 return NULL; 451 } 452 453 static void 454 hier_init(struct hier_iter *state, const char *local_realm, const char *server_realm) 455 { 456 size_t llen; 457 size_t slen; 458 size_t len = 0; 459 const char *lr; 460 const char *sr; 461 462 state->local_realm = local_realm; 463 state->server_realm = server_realm; 464 state->llen = llen = strlen(local_realm); 465 state->slen = slen = strlen(server_realm); 466 state->len = 0; 467 state->num = 0; 468 469 if (slen == 0 || llen == 0) 470 return; 471 472 /* Find first difference from the back */ 473 for (lr = local_realm + llen, sr = server_realm + slen; 474 lr != local_realm && sr != server_realm; 475 --lr, --sr) { 476 if (lr[-1] != sr[-1]) 477 break; 478 if (lr[-1] == '.') 479 len = llen - (lr - local_realm); 480 } 481 482 /* Nothing in common? */ 483 if (*lr == '\0') 484 return; 485 486 /* Everything in common? */ 487 if (llen == slen && lr == local_realm) 488 return; 489 490 /* Is one realm is a suffix of the other? */ 491 if ((llen < slen && lr == local_realm && sr[-1] == '.') || 492 (llen > slen && sr == server_realm && lr[-1] == '.')) 493 len = llen - (lr - local_realm); 494 495 state->len = len; 496 /* `lr` starts at local realm and walks up the tree to common suffix */ 497 state->lr = local_realm; 498 /* `sr` starts at common suffix in server realm and walks down the tree */ 499 state->sr = server_realm + slen - len; 500 501 /* Count elements and reset */ 502 while (hier_next(state) != NULL) 503 ++state->num; 504 state->lr = local_realm; 505 state->sr = server_realm + slen - len; 506 } 507 508 /* 509 * Find a referral path from client_realm to server_realm via local_realm. 510 * Either via [capaths] or hierarchicaly. 511 */ 512 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 513 _krb5_find_capath(krb5_context context, 514 const char *client_realm, 515 const char *local_realm, 516 const char *server_realm, 517 krb5_boolean use_hierarchical, 518 char ***rpath, 519 size_t *npath) 520 { 521 char **confpath; 522 char **capath; 523 struct hier_iter hier_state; 524 char **rp; 525 const char *r; 526 527 *rpath = NULL; 528 *npath = 0; 529 530 confpath = krb5_config_get_strings(context, NULL, "capaths", 531 client_realm, server_realm, NULL); 532 if (confpath == NULL) 533 confpath = krb5_config_get_strings(context, NULL, "capaths", 534 local_realm, server_realm, NULL); 535 /* 536 * With a [capaths] setting from the client to the server we look for our 537 * own realm in the list. If our own realm is not present, we return the 538 * full list. Otherwise, we return our realm's successors, or possibly 539 * NULL. Ignoring a [capaths] settings risks loops plus would violate 540 * explicit policy and the principle of least surpise. 541 */ 542 if (confpath != NULL) { 543 char **start = confpath; 544 size_t i; 545 size_t n; 546 547 for (rp = start; *rp; rp++) 548 if (strcmp(*rp, local_realm) == 0) 549 start = rp+1; 550 n = rp - start; 551 552 if (n == 0) { 553 krb5_config_free_strings(confpath); 554 return 0; 555 } 556 557 capath = calloc(n + 1, sizeof(*capath)); 558 if (capath == NULL) { 559 krb5_config_free_strings(confpath); 560 return krb5_enomem(context); 561 } 562 563 for (i = 0, rp = start; *rp; rp++) { 564 if ((capath[i++] = strdup(*rp)) == NULL) { 565 _krb5_free_capath(context, capath); 566 krb5_config_free_strings(confpath); 567 return krb5_enomem(context); 568 } 569 } 570 krb5_config_free_strings(confpath); 571 capath[i] = NULL; 572 *rpath = capath; 573 *npath = n; 574 return 0; 575 } 576 577 /* The use_hierarchical flag makes hierarchical path lookup unconditional */ 578 if (! use_hierarchical && 579 ! krb5_config_get_bool_default(context, NULL, TRUE, "libdefaults", 580 "allow_hierarchical_capaths", NULL)) 581 return 0; 582 583 /* 584 * When validating transit paths, local_realm == client_realm. Otherwise, 585 * with hierarchical referrals, they may differ, and we may be building a 586 * path forward from our own realm! 587 */ 588 hier_init(&hier_state, local_realm, server_realm); 589 if (hier_state.num == 0) 590 return 0; 591 592 rp = capath = calloc(hier_state.num + 1, sizeof(*capath)); 593 if (capath == NULL) 594 return krb5_enomem(context); 595 while ((r = hier_next(&hier_state)) != NULL) { 596 if ((*rp++ = strdup(r)) == NULL) { 597 _krb5_free_capath(context, capath); 598 return krb5_enomem(context); 599 } 600 } 601 602 *rp = NULL; 603 *rpath = capath; 604 *npath = hier_state.num; 605 return 0; 606 } 607 608 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 609 krb5_check_transited(krb5_context context, 610 krb5_const_realm client_realm, 611 krb5_const_realm server_realm, 612 krb5_realm *realms, 613 unsigned int num_realms, 614 int *bad_realm) 615 { 616 krb5_error_code ret = 0; 617 char **capath = NULL; 618 size_t num_capath = 0; 619 size_t i = 0; 620 size_t j = 0; 621 622 /* In transit checks hierarchical capaths are optional */ 623 ret = _krb5_find_capath(context, client_realm, client_realm, server_realm, 624 FALSE, &capath, &num_capath); 625 if (ret) 626 return ret; 627 628 for (i = 0; i < num_realms; i++) { 629 for (j = 0; j < num_capath; ++j) { 630 if (strcmp(realms[i], capath[j]) == 0) 631 break; 632 } 633 if (j == num_capath) { 634 _krb5_free_capath(context, capath); 635 krb5_set_error_message (context, KRB5KRB_AP_ERR_ILL_CR_TKT, 636 N_("no transit allowed " 637 "through realm %s from %s to %s", ""), 638 realms[i], client_realm, server_realm); 639 if (bad_realm) 640 *bad_realm = i; 641 return KRB5KRB_AP_ERR_ILL_CR_TKT; 642 } 643 } 644 645 _krb5_free_capath(context, capath); 646 return 0; 647 } 648 649 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 650 krb5_check_transited_realms(krb5_context context, 651 const char *const *realms, 652 unsigned int num_realms, 653 int *bad_realm) 654 { 655 size_t i; 656 int ret = 0; 657 char **bad_realms = krb5_config_get_strings(context, NULL, 658 "libdefaults", 659 "transited_realms_reject", 660 NULL); 661 if(bad_realms == NULL) 662 return 0; 663 664 for(i = 0; i < num_realms; i++) { 665 char **p; 666 for(p = bad_realms; *p; p++) 667 if(strcmp(*p, realms[i]) == 0) { 668 ret = KRB5KRB_AP_ERR_ILL_CR_TKT; 669 krb5_set_error_message (context, ret, 670 N_("no transit allowed " 671 "through realm %s", ""), 672 *p); 673 if(bad_realm) 674 *bad_realm = i; 675 break; 676 } 677 } 678 krb5_config_free_strings(bad_realms); 679 return ret; 680 } 681 682 #if 0 683 int 684 main(int argc, char **argv) 685 { 686 krb5_data x; 687 char **r; 688 int num, i; 689 x.data = argv[1]; 690 x.length = strlen(x.data); 691 if(domain_expand(x, &r, &num, argv[2], argv[3])) 692 exit(1); 693 for(i = 0; i < num; i++) 694 printf("%s\n", r[i]); 695 return 0; 696 } 697 #endif 698
Indexes created Sat Feb 28 05:31:39 UTC 2026