get_host_realm.c revision 1.1.1.1.10.1
1/* $NetBSD: get_host_realm.c,v 1.1.1.1.10.1 2014/08/19 23:45:19 tls Exp $ */ 2 3/* 4 * Copyright (c) 1997 - 2005 Kungliga Tekniska H��gskolan 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#include <krb5/resolve.h> 38 39/* To automagically find the correct realm of a host (without 40 * [domain_realm] in krb5.conf) add a text record for your domain with 41 * the name of your realm, like this: 42 * 43 * _kerberos IN TXT "FOO.SE" 44 * 45 * The search is recursive, so you can add entries for specific 46 * hosts. To find the realm of host a.b.c, it first tries 47 * _kerberos.a.b.c, then _kerberos.b.c and so on. 48 * 49 * This method is described in draft-ietf-cat-krb-dns-locate-03.txt. 50 * 51 */ 52 53static int 54copy_txt_to_realms (struct rk_resource_record *head, 55 krb5_realm **realms) 56{ 57 struct rk_resource_record *rr; 58 unsigned int n, i; 59 60 for(n = 0, rr = head; rr; rr = rr->next) 61 if (rr->type == rk_ns_t_txt) 62 ++n; 63 64 if (n == 0) 65 return -1; 66 67 *realms = malloc ((n + 1) * sizeof(krb5_realm)); 68 if (*realms == NULL) 69 return -1; 70 71 for (i = 0; i < n + 1; ++i) 72 (*realms)[i] = NULL; 73 74 for (i = 0, rr = head; rr; rr = rr->next) { 75 if (rr->type == rk_ns_t_txt) { 76 char *tmp; 77 78 tmp = strdup(rr->u.txt); 79 if (tmp == NULL) { 80 for (i = 0; i < n; ++i) 81 free ((*realms)[i]); 82 free (*realms); 83 return -1; 84 } 85 (*realms)[i] = tmp; 86 ++i; 87 } 88 } 89 return 0; 90} 91 92static int 93dns_find_realm(krb5_context context, 94 const char *domain, 95 krb5_realm **realms) 96{ 97 static const char *default_labels[] = { "_kerberos", NULL }; 98 char dom[MAXHOSTNAMELEN]; 99 struct rk_dns_reply *r; 100 const char **labels; 101 char **config_labels; 102 int i, ret; 103 104 config_labels = krb5_config_get_strings(context, NULL, "libdefaults", 105 "dns_lookup_realm_labels", NULL); 106 if(config_labels != NULL) 107 labels = (const char **)config_labels; 108 else 109 labels = default_labels; 110 if(*domain == '.') 111 domain++; 112 for (i = 0; labels[i] != NULL; i++) { 113 ret = snprintf(dom, sizeof(dom), "%s.%s.", labels[i], domain); 114 if(ret < 0 || (size_t)ret >= sizeof(dom)) { 115 if (config_labels) 116 krb5_config_free_strings(config_labels); 117 return -1; 118 } 119 r = rk_dns_lookup(dom, "TXT"); 120 if(r != NULL) { 121 ret = copy_txt_to_realms (r->head, realms); 122 rk_dns_free_data(r); 123 if(ret == 0) { 124 if (config_labels) 125 krb5_config_free_strings(config_labels); 126 return 0; 127 } 128 } 129 } 130 if (config_labels) 131 krb5_config_free_strings(config_labels); 132 return -1; 133} 134 135/* 136 * Try to figure out what realms host in `domain' belong to from the 137 * configuration file. 138 */ 139 140static int 141config_find_realm(krb5_context context, 142 const char *domain, 143 krb5_realm **realms) 144{ 145 char **tmp = krb5_config_get_strings (context, NULL, 146 "domain_realm", 147 domain, 148 NULL); 149 150 if (tmp == NULL) 151 return -1; 152 *realms = tmp; 153 return 0; 154} 155 156/* 157 * This function assumes that `host' is a FQDN (and doesn't handle the 158 * special case of host == NULL either). 159 * Try to find mapping in the config file or DNS and it that fails, 160 * fall back to guessing 161 */ 162 163KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 164_krb5_get_host_realm_int (krb5_context context, 165 const char *host, 166 krb5_boolean use_dns, 167 krb5_realm **realms) 168{ 169 const char *p, *q; 170 krb5_boolean dns_locate_enable; 171 172 dns_locate_enable = krb5_config_get_bool_default(context, NULL, TRUE, 173 "libdefaults", "dns_lookup_realm", NULL); 174 for (p = host; p != NULL; p = strchr (p + 1, '.')) { 175 if(config_find_realm(context, p, realms) == 0) { 176 if(strcasecmp(*realms[0], "dns_locate") == 0) { 177 if(use_dns) 178 for (q = host; q != NULL; q = strchr(q + 1, '.')) 179 if(dns_find_realm(context, q, realms) == 0) 180 return 0; 181 continue; 182 } else 183 return 0; 184 } 185 else if(use_dns && dns_locate_enable) { 186 if(dns_find_realm(context, p, realms) == 0) 187 return 0; 188 } 189 } 190 p = strchr(host, '.'); 191 if(p != NULL) { 192 p++; 193 *realms = malloc(2 * sizeof(krb5_realm)); 194 if (*realms == NULL) { 195 krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", "")); 196 return ENOMEM; 197 } 198 199 (*realms)[0] = strdup(p); 200 if((*realms)[0] == NULL) { 201 free(*realms); 202 krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", "")); 203 return ENOMEM; 204 } 205 strupr((*realms)[0]); 206 (*realms)[1] = NULL; 207 return 0; 208 } 209 krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN, 210 N_("unable to find realm of host %s", ""), 211 host); 212 return KRB5_ERR_HOST_REALM_UNKNOWN; 213} 214 215/* 216 * Return the realm(s) of `host' as a NULL-terminated list in 217 * `realms'. Free `realms' with krb5_free_host_realm(). 218 */ 219 220KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL 221krb5_get_host_realm(krb5_context context, 222 const char *targethost, 223 krb5_realm **realms) 224{ 225 const char *host = targethost; 226 char hostname[MAXHOSTNAMELEN]; 227 krb5_error_code ret; 228 int use_dns; 229 230 if (host == NULL) { 231 if (gethostname (hostname, sizeof(hostname))) { 232 *realms = NULL; 233 return errno; 234 } 235 host = hostname; 236 } 237 238 /* 239 * If our local hostname is without components, don't even try to dns. 240 */ 241 242 use_dns = (strchr(host, '.') != NULL); 243 244 ret = _krb5_get_host_realm_int (context, host, use_dns, realms); 245 if (ret && targethost != NULL) { 246 /* 247 * If there was no realm mapping for the host (and we wasn't 248 * looking for ourself), guess at the local realm, maybe our 249 * KDC knows better then we do and we get a referral back. 250 */ 251 ret = krb5_get_default_realms(context, realms); 252 if (ret) { 253 krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN, 254 N_("Unable to find realm of host %s", ""), 255 host); 256 return KRB5_ERR_HOST_REALM_UNKNOWN; 257 } 258 } 259 return ret; 260} 261