lib/krb5/transited.c

   1 /*
   2  * Copyright (c) 1997 - 2001, 2003 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35
  36 RCSID("$Id$");
  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     const char *p;
  68     struct tr_realm *path = r->next;
  69     struct tr_realm *tmp;
  70
  71     if(strlen(from) < strlen(to)){
  72         const char *str;
  73         str = from;
  74         from = to;
  75         to = str;
  76     }
  77
  78     if(strcmp(from + strlen(from) - strlen(to), to) == 0){
  79         p = from;
  80         while(1){
  81             p = strchr(p, '.');
  82             if(p == NULL) {
  83                 krb5_clear_error_string (context);
  84                 return KRB5KDC_ERR_POLICY;
  85             }
  86             p++;
  87             if(strcmp(p, to) == 0)
  88                 break;
  89             tmp = calloc(1, sizeof(*tmp));
  90             if(tmp == NULL){
  91                 krb5_set_error_string (context, "malloc: out of memory");
  92                 return ENOMEM;
  93             }
  94             tmp->next = path;
  95             path = tmp;
  96             path->realm = strdup(p);
  97             if(path->realm == NULL){
  98                 r->next = path; /* XXX */
  99                 krb5_set_error_string (context, "malloc: out of memory");
 100                 return ENOMEM;;
 101             }
 102         }
 103     }else if(strncmp(from, to, strlen(to)) == 0){
 104         p = from + strlen(from);
 105         while(1){
 106             while(p >= from && *p != '/') p--;
 107             if(p == from) {
 108                 r->next = path; /* XXX */
 109                 return KRB5KDC_ERR_POLICY;
 110             }
 111             if(strncmp(to, from, p - from) == 0)
 112                 break;
 113             tmp = calloc(1, sizeof(*tmp));
 114             if(tmp == NULL){
 115                 krb5_set_error_string (context, "malloc: out of memory");
 116                 return ENOMEM;
 117             }
 118             tmp->next = path;
 119             path = tmp;
 120             path->realm = malloc(p - from + 1);
 121             if(path->realm == NULL){
 122                 r->next = path; /* XXX */
 123                 krb5_set_error_string (context, "malloc: out of memory");
 124                 return ENOMEM;
 125             }
 126             memcpy(path->realm, from, p - from);
 127             path->realm[p - from] = '\0';
 128             p--;
 129         }
 130     } else {
 131         krb5_clear_error_string (context);
 132         return KRB5KDC_ERR_POLICY;
 133     }
 134     r->next = path;
 135
 136     return 0;
 137 }
 138
 139 static int
 140 make_paths(krb5_context context,
 141            struct tr_realm *realms, const char *client_realm,
 142            const char *server_realm)
 143 {
 144     struct tr_realm *r;
 145     int ret;
 146     const char *prev_realm = client_realm;
 147     const char *next_realm = NULL;
 148     for(r = realms; r; r = r->next){
 149         /* it *might* be that you can have more than one empty
 150            component in a row, at least that's how I interpret the
 151            "," exception in 1510 */
 152         if(r->realm[0] == '\0'){
 153             while(r->next && r->next->realm[0] == '\0')
 154                 r = r->next;
 155             if(r->next)
 156                 next_realm = r->next->realm;
 157             else
 158                 next_realm = server_realm;
 159             ret = make_path(context, r, prev_realm, next_realm);
 160             if(ret){
 161                 free_realms(realms);
 162                 return ret;
 163             }
 164         }
 165         prev_realm = r->realm;
 166     }
 167     return 0;
 168 }
 169
 170 static int
 171 expand_realms(krb5_context context,
 172               struct tr_realm *realms, const char *client_realm)
 173 {
 174     struct tr_realm *r;
 175     const char *prev_realm = NULL;
 176     for(r = realms; r; r = r->next){
 177         if(r->trailing_dot){
 178             char *tmp;
 179             size_t len;
 180
 181             if(prev_realm == NULL)
 182                 prev_realm = client_realm;
 183
 184             len = strlen(r->realm) + strlen(prev_realm) + 1;
 185
 186             tmp = realloc(r->realm, len);
 187             if(tmp == NULL){
 188                 free_realms(realms);
 189                 krb5_set_error_string (context, "malloc: out of memory");
 190                 return ENOMEM;
 191             }
 192             r->realm = tmp;
 193             strlcat(r->realm, prev_realm, len);
 194         }else if(r->leading_slash && !r->leading_space && prev_realm){
 195             /* yet another exception: if you use x500-names, the
 196                leading realm doesn't have to be "quoted" with a space */
 197             char *tmp;
 198             size_t len = strlen(r->realm) + strlen(prev_realm) + 1;
 199
 200             tmp = malloc(len);
 201             if(tmp == NULL){
 202                 free_realms(realms);
 203                 krb5_set_error_string (context, "malloc: out of memory");
 204                 return ENOMEM;
 205             }
 206             strlcpy(tmp, prev_realm, len);
 207             strlcat(tmp, r->realm, len);
 208             free(r->realm);
 209             r->realm = tmp;
 210         }
 211         prev_realm = r->realm;
 212     }
 213     return 0;
 214 }
 215
 216 static struct tr_realm *
 217 make_realm(char *realm)
 218 {
 219     struct tr_realm *r;
 220     char *p, *q;
 221     int quote = 0;
 222     r = calloc(1, sizeof(*r));
 223     if(r == NULL){
 224         free(realm);
 225         return NULL;
 226     }
 227     r->realm = realm;
 228     for(p = q = r->realm; *p; p++){
 229         if(p == r->realm && *p == ' '){
 230             r->leading_space = 1;
 231             continue;
 232         }
 233         if(q == r->realm && *p == '/')
 234             r->leading_slash = 1;
 235         if(quote){
 236             *q++ = *p;
 237             quote = 0;
 238             continue;
 239         }
 240         if(*p == '\\'){
 241             quote = 1;
 242             continue;
 243         }
 244         if(p[0] == '.' && p[1] == '\0')
 245             r->trailing_dot = 1;
 246         *q++ = *p;
 247     }
 248     *q = '\0';
 249     return r;
 250 }
 251
 252 static struct tr_realm*
 253 append_realm(struct tr_realm *head, struct tr_realm *r)
 254 {
 255     struct tr_realm *p;
 256     if(head == NULL){
 257         r->next = NULL;
 258         return r;
 259     }
 260     p = head;
 261     while(p->next) p = p->next;
 262     p->next = r;
 263     return head;
 264 }
 265
 266 static int
 267 decode_realms(krb5_context context,
 268               const char *tr, int length, struct tr_realm **realms)
 269 {
 270     struct tr_realm *r = NULL;
 271
 272     char *tmp;
 273     int quote = 0;
 274     const char *start = tr;
 275     int i;
 276
 277     for(i = 0; i < length; i++){
 278         if(quote){
 279             quote = 0;
 280             continue;
 281         }
 282         if(tr[i] == '\\'){
 283             quote = 1;
 284             continue;
 285         }
 286         if(tr[i] == ','){
 287             tmp = malloc(tr + i - start + 1);
 288             if(tmp == NULL){
 289                 krb5_set_error_string (context, "malloc: out of memory");
 290                 return ENOMEM;
 291             }
 292             memcpy(tmp, start, tr + i - start);
 293             tmp[tr + i - start] = '\0';
 294             r = make_realm(tmp);
 295             if(r == NULL){
 296                 free_realms(*realms);
 297                 krb5_set_error_string (context, "malloc: out of memory");
 298                 return ENOMEM;
 299             }
 300             *realms = append_realm(*realms, r);
 301             start = tr + i + 1;
 302         }
 303     }
 304     tmp = malloc(tr + i - start + 1);
 305     if(tmp == NULL){
 306         free(*realms);
 307         krb5_set_error_string (context, "malloc: out of memory");
 308         return ENOMEM;
 309     }
 310     memcpy(tmp, start, tr + i - start);
 311     tmp[tr + i - start] = '\0';
 312     r = make_realm(tmp);
 313     if(r == NULL){
 314         free_realms(*realms);
 315         krb5_set_error_string (context, "malloc: out of memory");
 316         return ENOMEM;
 317     }
 318     *realms = append_realm(*realms, r);
 319
 320     return 0;
 321 }
 322
 323
 324 krb5_error_code KRB5_LIB_FUNCTION
 325 krb5_domain_x500_decode(krb5_context context,
 326                         krb5_data tr, char ***realms, int *num_realms,
 327                         const char *client_realm, const char *server_realm)
 328 {
 329     struct tr_realm *r = NULL;
 330     struct tr_realm *p, **q;
 331     int ret;
 332
 333     if(tr.length == 0) {
 334         *realms = NULL;
 335         *num_realms = 0;
 336         return 0;
 337     }
 338
 339     /* split string in components */
 340     ret = decode_realms(context, tr.data, tr.length, &r);
 341     if(ret)
 342         return ret;
 343
 344     /* apply prefix rule */
 345     ret = expand_realms(context, r, client_realm);
 346     if(ret)
 347         return ret;
 348
 349     ret = make_paths(context, r, client_realm, server_realm);
 350     if(ret)
 351         return ret;
 352
 353     /* remove empty components and count realms */
 354     q = &r;
 355     *num_realms = 0;
 356     for(p = r; p; ){
 357         if(p->realm[0] == '\0'){
 358             free(p->realm);
 359             *q = p->next;
 360             free(p);
 361             p = *q;
 362         }else{
 363             q = &p->next;
 364             p = p->next;
 365             (*num_realms)++;
 366         }
 367     }
 368     if (*num_realms < 0 || *num_realms + 1 > UINT_MAX/sizeof(**realms))
 369         return ERANGE;
 370
 371     {
 372         char **R;
 373         R = malloc((*num_realms + 1) * sizeof(*R));
 374         if (R == NULL)
 375             return ENOMEM;
 376         *realms = R;
 377         while(r){
 378             *R++ = r->realm;
 379             p = r->next;
 380             free(r);
 381             r = p;
 382         }
 383     }
 384     return 0;
 385 }
 386
 387 krb5_error_code KRB5_LIB_FUNCTION
 388 krb5_domain_x500_encode(char **realms, int num_realms, krb5_data *encoding)
 389 {
 390     char *s = NULL;
 391     int len = 0;
 392     int i;
 393     krb5_data_zero(encoding);
 394     if (num_realms == 0)
 395         return 0;
 396     for(i = 0; i < num_realms; i++){
 397         len += strlen(realms[i]);
 398         if(realms[i][0] == '/')
 399             len++;
 400     }
 401     len += num_realms - 1;
 402     s = malloc(len + 1);
 403     if (s == NULL)
 404         return ENOMEM;
 405     *s = '\0';
 406     for(i = 0; i < num_realms; i++){
 407         if(i && i < num_realms - 1)
 408             strlcat(s, ",", len + 1);
 409         if(realms[i][0] == '/')
 410             strlcat(s, " ", len + 1);
 411         strlcat(s, realms[i], len + 1);
 412     }
 413     encoding->data = s;
 414     encoding->length = strlen(s);
 415     return 0;
 416 }
 417
 418 krb5_error_code KRB5_LIB_FUNCTION
 419 krb5_check_transited(krb5_context context,
 420                      krb5_const_realm client_realm,
 421                      krb5_const_realm server_realm,
 422                      krb5_realm *realms,
 423                      int num_realms,
 424                      int *bad_realm)
 425 {
 426     char **tr_realms;
 427     char **p;
 428     int i;
 429
 430     if(num_realms == 0)
 431         return 0;
 432
 433     tr_realms = krb5_config_get_strings(context, NULL,
 434                                         "capaths",
 435                                         client_realm,
 436                                         server_realm,
 437                                         NULL);
 438     for(i = 0; i < num_realms; i++) {
 439         for(p = tr_realms; p && *p; p++) {
 440             if(strcmp(*p, realms[i]) == 0)
 441                 break;
 442         }
 443         if(p == NULL || *p == NULL) {
 444             krb5_config_free_strings(tr_realms);
 445             krb5_set_error_string (context, "no transit through realm %s",
 446                                    realms[i]);
 447             if(bad_realm)
 448                 *bad_realm = i;
 449             return KRB5KRB_AP_ERR_ILL_CR_TKT;
 450         }
 451     }
 452     krb5_config_free_strings(tr_realms);
 453     return 0;
 454 }
 455
 456 krb5_error_code KRB5_LIB_FUNCTION
 457 krb5_check_transited_realms(krb5_context context,
 458                             const char *const *realms,
 459                             int num_realms,
 460                             int *bad_realm)
 461 {
 462     int i;
 463     int ret = 0;
 464     char **bad_realms = krb5_config_get_strings(context, NULL,
 465                                                 "libdefaults",
 466                                                 "transited_realms_reject",
 467                                                 NULL);
 468     if(bad_realms == NULL)
 469         return 0;
 470
 471     for(i = 0; i < num_realms; i++) {
 472         char **p;
 473         for(p = bad_realms; *p; p++)
 474             if(strcmp(*p, realms[i]) == 0) {
 475                 krb5_set_error_string (context, "no transit through realm %s",
 476                                        *p);
 477                 ret = KRB5KRB_AP_ERR_ILL_CR_TKT;
 478                 if(bad_realm)
 479                     *bad_realm = i;
 480                 break;
 481             }
 482     }
 483     krb5_config_free_strings(bad_realms);
 484     return ret;
 485 }
 486
 487 #if 0
 488 int
 489 main(int argc, char **argv)
 490 {
 491     krb5_data x;
 492     char **r;
 493     int num, i;
 494     x.data = argv[1];
 495     x.length = strlen(x.data);
 496     if(domain_expand(x, &r, &num, argv[2], argv[3]))
 497         exit(1);
 498     for(i = 0; i < num; i++)
 499         printf("%s\n", r[i]);
 500     return 0;
 501 }
 502 #endif
 503