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 *tmp;
  73         tmp = from;
  74         from = to;
  75         to = tmp;
  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             tmp->next = path;
  91             path = tmp;
  92             path->realm = strdup(p);
  93             if(path->realm == NULL){
  94                 r->next = path; /* XXX */
  95                 krb5_set_error_string (context, "malloc: out of memory");
  96                 return ENOMEM;;
  97             }
  98         }
  99     }else if(strncmp(from, to, strlen(to)) == 0){
 100         p = from + strlen(from);
 101         while(1){
 102             while(p >= from && *p != '/') p--;
 103             if(p == from)
 104                 return KRB5KDC_ERR_POLICY;
 105             if(strncmp(to, from, p - from) == 0)
 106                 break;
 107             tmp = calloc(1, sizeof(*tmp));
 108             tmp->next = path;
 109             path = tmp;
 110             path->realm = malloc(p - from + 1);
 111             if(path->realm == NULL){
 112                 r->next = path; /* XXX */
 113                 krb5_set_error_string (context, "malloc: out of memory");
 114                 return ENOMEM;
 115             }
 116             memcpy(path->realm, from, p - from);
 117             path->realm[p - from] = '\0';
 118             p--;
 119         }
 120     } else {
 121         krb5_clear_error_string (context);
 122         return KRB5KDC_ERR_POLICY;
 123     }
 124     r->next = path;
 125
 126     return 0;
 127 }
 128
 129 static int
 130 make_paths(krb5_context context,
 131            struct tr_realm *realms, const char *client_realm,
 132            const char *server_realm)
 133 {
 134     struct tr_realm *r;
 135     int ret;
 136     const char *prev_realm = client_realm;
 137     const char *next_realm = NULL;
 138     for(r = realms; r; r = r->next){
 139         /* it *might* be that you can have more than one empty
 140            component in a row, at least that's how I interpret the
 141            "," exception in 1510 */
 142         if(r->realm[0] == '\0'){
 143             while(r->next && r->next->realm[0] == '\0')
 144                 r = r->next;
 145             if(r->next)
 146                 next_realm = r->next->realm;
 147             else
 148                 next_realm = server_realm;
 149             ret = make_path(context, r, prev_realm, next_realm);
 150             if(ret){
 151                 free_realms(realms);
 152                 return ret;
 153             }
 154         }
 155         prev_realm = r->realm;
 156     }
 157     return 0;
 158 }
 159
 160 static int
 161 expand_realms(krb5_context context,
 162               struct tr_realm *realms, const char *client_realm)
 163 {
 164     struct tr_realm *r;
 165     const char *prev_realm = NULL;
 166     for(r = realms; r; r = r->next){
 167         if(r->trailing_dot){
 168             char *tmp;
 169             size_t len = strlen(r->realm) + strlen(prev_realm) + 1;
 170
 171             if(prev_realm == NULL)
 172                 prev_realm = client_realm;
 173             tmp = realloc(r->realm, len);
 174             if(tmp == NULL){
 175                 free_realms(realms);
 176                 krb5_set_error_string (context, "malloc: out of memory");
 177                 return ENOMEM;
 178             }
 179             r->realm = tmp;
 180             strlcat(r->realm, prev_realm, len);
 181         }else if(r->leading_slash && !r->leading_space && prev_realm){
 182             /* yet another exception: if you use x500-names, the
 183                leading realm doesn't have to be "quoted" with a space */
 184             char *tmp;
 185             size_t len = strlen(r->realm) + strlen(prev_realm) + 1;
 186
 187             tmp = malloc(len);
 188             if(tmp == NULL){
 189                 free_realms(realms);
 190                 krb5_set_error_string (context, "malloc: out of memory");
 191                 return ENOMEM;
 192             }
 193             strlcpy(tmp, prev_realm, len);
 194             strlcat(tmp, r->realm, len);
 195             free(r->realm);
 196             r->realm = tmp;
 197         }
 198         prev_realm = r->realm;
 199     }
 200     return 0;
 201 }
 202
 203 static struct tr_realm *
 204 make_realm(char *realm)
 205 {
 206     struct tr_realm *r;
 207     char *p, *q;
 208     int quote = 0;
 209     r = calloc(1, sizeof(*r));
 210     if(r == NULL){
 211         free(realm);
 212         return NULL;
 213     }
 214     r->realm = realm;
 215     for(p = q = r->realm; *p; p++){
 216         if(p == r->realm && *p == ' '){
 217             r->leading_space = 1;
 218             continue;
 219         }
 220         if(q == r->realm && *p == '/')
 221             r->leading_slash = 1;
 222         if(quote){
 223             *q++ = *p;
 224             quote = 0;
 225             continue;
 226         }
 227         if(*p == '\\'){
 228             quote = 1;
 229             continue;
 230         }
 231         if(p[0] == '.' && p[1] == '\0')
 232             r->trailing_dot = 1;
 233         *q++ = *p;
 234     }
 235     *q = '\0';
 236     return r;
 237 }
 238
 239 static struct tr_realm*
 240 append_realm(struct tr_realm *head, struct tr_realm *r)
 241 {
 242     struct tr_realm *p;
 243     if(head == NULL){
 244         r->next = NULL;
 245         return r;
 246     }
 247     p = head;
 248     while(p->next) p = p->next;
 249     p->next = r;
 250     return head;
 251 }
 252
 253 static int
 254 decode_realms(krb5_context context,
 255               const char *tr, int length, struct tr_realm **realms)
 256 {
 257     struct tr_realm *r = NULL;
 258
 259     char *tmp;
 260     int quote = 0;
 261     const char *start = tr;
 262     int i;
 263
 264     for(i = 0; i < length; i++){
 265         if(quote){
 266             quote = 0;
 267             continue;
 268         }
 269         if(tr[i] == '\\'){
 270             quote = 1;
 271             continue;
 272         }
 273         if(tr[i] == ','){
 274             tmp = malloc(tr + i - start + 1);
 275             memcpy(tmp, start, tr + i - start);
 276             tmp[tr + i - start] = '\0';
 277             r = make_realm(tmp);
 278             if(r == NULL){
 279                 free_realms(*realms);
 280                 krb5_set_error_string (context, "malloc: out of memory");
 281                 return ENOMEM;
 282             }
 283             *realms = append_realm(*realms, r);
 284             start = tr + i + 1;
 285         }
 286     }
 287     tmp = malloc(tr + i - start + 1);
 288     memcpy(tmp, start, tr + i - start);
 289     tmp[tr + i - start] = '\0';
 290     r = make_realm(tmp);
 291     if(r == NULL){
 292         free_realms(*realms);
 293         krb5_set_error_string (context, "malloc: out of memory");
 294         return ENOMEM;
 295     }
 296     *realms = append_realm(*realms, r);
 297
 298     return 0;
 299 }
 300
 301
 302 krb5_error_code
 303 krb5_domain_x500_decode(krb5_context context,
 304                         krb5_data tr, char ***realms, int *num_realms,
 305                         const char *client_realm, const char *server_realm)
 306 {
 307     struct tr_realm *r = NULL;
 308     struct tr_realm *p, **q;
 309     int ret;
 310
 311     if(tr.length == 0) {
 312         *realms = NULL;
 313         *num_realms = 0;
 314         return 0;
 315     }
 316
 317     /* split string in components */
 318     ret = decode_realms(context, tr.data, tr.length, &r);
 319     if(ret)
 320         return ret;
 321
 322     /* apply prefix rule */
 323     ret = expand_realms(context, r, client_realm);
 324     if(ret)
 325         return ret;
 326
 327     ret = make_paths(context, r, client_realm, server_realm);
 328     if(ret)
 329         return ret;
 330
 331     /* remove empty components and count realms */
 332     q = &r;
 333     *num_realms = 0;
 334     for(p = r; p; ){
 335         if(p->realm[0] == '\0'){
 336             free(p->realm);
 337             *q = p->next;
 338             free(p);
 339             p = *q;
 340         }else{
 341             q = &p->next;
 342             p = p->next;
 343             (*num_realms)++;
 344         }
 345     }
 346     if (*num_realms < 0 || *num_realms + 1 > UINT_MAX/sizeof(**realms))
 347         return ERANGE;
 348
 349     {
 350         char **R;
 351         R = malloc((*num_realms + 1) * sizeof(*R));
 352         if (R == NULL)
 353             return ENOMEM;
 354         *realms = R;
 355         while(r){
 356             *R++ = r->realm;
 357             p = r->next;
 358             free(r);
 359             r = p;
 360         }
 361     }
 362     return 0;
 363 }
 364
 365 krb5_error_code
 366 krb5_domain_x500_encode(char **realms, int num_realms, krb5_data *encoding)
 367 {
 368     char *s = NULL;
 369     int len = 0;
 370     int i;
 371     krb5_data_zero(encoding);
 372     if (num_realms == 0)
 373         return 0;
 374     for(i = 0; i < num_realms; i++){
 375         len += strlen(realms[i]);
 376         if(realms[i][0] == '/')
 377             len++;
 378     }
 379     len += num_realms - 1;
 380     s = malloc(len + 1);
 381     if (s == NULL)
 382         return ENOMEM;
 383     *s = '\0';
 384     for(i = 0; i < num_realms; i++){
 385         if(i && i < num_realms - 1)
 386             strlcat(s, ",", len + 1);
 387         if(realms[i][0] == '/')
 388             strlcat(s, " ", len + 1);
 389         strlcat(s, realms[i], len + 1);
 390     }
 391     encoding->data = s;
 392     encoding->length = strlen(s);
 393     return 0;
 394 }
 395
 396 krb5_error_code
 397 krb5_check_transited(krb5_context context,
 398                      krb5_const_realm client_realm,
 399                      krb5_const_realm server_realm,
 400                      krb5_realm *realms,
 401                      int num_realms,
 402                      int *bad_realm)
 403 {
 404     char **tr_realms;
 405     char **p;
 406     int i;
 407
 408     if(num_realms == 0)
 409         return 0;
 410
 411     tr_realms = krb5_config_get_strings(context, NULL,
 412                                         "capaths",
 413                                         client_realm,
 414                                         server_realm,
 415                                         NULL);
 416     for(i = 0; i < num_realms; i++) {
 417         for(p = tr_realms; p && *p; p++) {
 418             if(strcmp(*p, realms[i]) == 0)
 419                 break;
 420         }
 421         if(p == NULL || *p == NULL) {
 422             krb5_config_free_strings(tr_realms);
 423             krb5_set_error_string (context, "no transit through realm %s",
 424                                    realms[i]);
 425             if(bad_realm)
 426                 *bad_realm = i;
 427             return KRB5KRB_AP_ERR_ILL_CR_TKT;
 428         }
 429     }
 430     krb5_config_free_strings(tr_realms);
 431     return 0;
 432 }
 433
 434 krb5_error_code
 435 krb5_check_transited_realms(krb5_context context,
 436                             const char *const *realms,
 437                             int num_realms,
 438                             int *bad_realm)
 439 {
 440     int i;
 441     int ret = 0;
 442     char **bad_realms = krb5_config_get_strings(context, NULL,
 443                                                 "libdefaults",
 444                                                 "transited_realms_reject",
 445                                                 NULL);
 446     if(bad_realms == NULL)
 447         return 0;
 448
 449     for(i = 0; i < num_realms; i++) {
 450         char **p;
 451         for(p = bad_realms; *p; p++)
 452             if(strcmp(*p, realms[i]) == 0) {
 453                 krb5_set_error_string (context, "no transit through realm %s",
 454                                        *p);
 455                 ret = KRB5KRB_AP_ERR_ILL_CR_TKT;
 456                 if(bad_realm)
 457                     *bad_realm = i;
 458                 break;
 459             }
 460     }
 461     krb5_config_free_strings(bad_realms);
 462     return ret;
 463 }
 464
 465 #if 0
 466 int
 467 main(int argc, char **argv)
 468 {
 469     krb5_data x;
 470     char **r;
 471     int num, i;
 472     x.data = argv[1];
 473     x.length = strlen(x.data);
 474     if(domain_expand(x, &r, &num, argv[2], argv[3]))
 475         exit(1);
 476     for(i = 0; i < num; i++)
 477         printf("%s\n", r[i]);
 478     return 0;
 479 }
 480 #endif
 481