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-rw-r--r--third_party/heimdal/lib/krb5/get_host_realm.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/krb5/get_host_realm.c b/third_party/heimdal/lib/krb5/get_host_realm.c
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+++ b/third_party/heimdal/lib/krb5/get_host_realm.c
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+/*
+ * Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "krb5_locl.h"
+#include <resolve.h>
+
+/* To automagically find the correct realm of a host (without
+ * [domain_realm] in krb5.conf) add a text record for your domain with
+ * the name of your realm, like this:
+ *
+ * _kerberos IN TXT "FOO.SE"
+ *
+ * The search is recursive, so you can add entries for specific
+ * hosts. To find the realm of host a.b.c, it first tries
+ * _kerberos.a.b.c, then _kerberos.b.c and so on.
+ *
+ * This method is described in draft-ietf-cat-krb-dns-locate-03.txt.
+ *
+ */
+
+static int
+copy_txt_to_realms(krb5_context context,
+ const char *domain,
+ struct rk_resource_record *head,
+ krb5_realm **realms)
+{
+ struct rk_resource_record *rr;
+ unsigned int n, i;
+
+ for(n = 0, rr = head; rr; rr = rr->next)
+ if (rr->type == rk_ns_t_txt)
+ ++n;
+
+ if (n == 0)
+ return -1;
+
+ *realms = malloc ((n + 1) * sizeof(krb5_realm));
+ if (*realms == NULL)
+ return krb5_enomem(context);;
+
+ for (i = 0; i < n + 1; ++i)
+ (*realms)[i] = NULL;
+
+ for (i = 0, rr = head; rr; rr = rr->next) {
+ if (rr->type == rk_ns_t_txt) {
+ char *tmp = NULL;
+ int invalid_tld = 1;
+
+ /* Check for a gTLD controlled interruption */
+ if (strcmp("Your DNS configuration needs immediate "
+ "attention see https://icann.org/namecollision",
+ rr->u.txt) != 0) {
+ invalid_tld = 0;
+ tmp = strdup(rr->u.txt);
+ }
+ if (tmp == NULL) {
+ for (i = 0; i < n; ++i)
+ free ((*realms)[i]);
+ free (*realms);
+ if (invalid_tld) {
+ krb5_warnx(context,
+ "Realm lookup failed: "
+ "Domain '%s' needs immediate attention "
+ "see https://icann.org/namecollision",
+ domain);
+ return KRB5_KDC_UNREACH;
+ }
+ return krb5_enomem(context);;
+ }
+ (*realms)[i] = tmp;
+ ++i;
+ }
+ }
+ return 0;
+}
+
+static int
+dns_find_realm(krb5_context context,
+ const char *domain,
+ krb5_realm **realms)
+{
+ static const char *const default_labels[] = { "_kerberos", NULL };
+ char dom[MAXHOSTNAMELEN];
+ struct rk_dns_reply *r;
+ const char *const *labels;
+ char **config_labels;
+ int i, ret = 0;
+
+ config_labels = krb5_config_get_strings(context, NULL, "libdefaults",
+ "dns_lookup_realm_labels", NULL);
+ if(config_labels != NULL)
+ labels = (const char *const *)config_labels;
+ else
+ labels = default_labels;
+ if(*domain == '.')
+ domain++;
+ for (i = 0; labels[i] != NULL; i++) {
+ ret = snprintf(dom, sizeof(dom), "%s.%s.", labels[i], domain);
+ if(ret < 0 || (size_t)ret >= sizeof(dom)) {
+ ret = krb5_enomem(context);
+ goto out;
+ }
+ r = rk_dns_lookup(dom, "TXT");
+ if(r != NULL) {
+ ret = copy_txt_to_realms(context, domain, r->head, realms);
+ rk_dns_free_data(r);
+ if(ret == 0)
+ goto out;
+ }
+ }
+ krb5_set_error_message(context, KRB5_KDC_UNREACH,
+ "Realm lookup failed: "
+ "No DNS TXT record for %s",
+ domain);
+ ret = KRB5_KDC_UNREACH;
+out:
+ if (config_labels)
+ krb5_config_free_strings(config_labels);
+ return ret;
+}
+
+/*
+ * Try to figure out what realms host in `domain' belong to from the
+ * configuration file.
+ */
+
+static int
+config_find_realm(krb5_context context,
+ const char *domain,
+ krb5_realm **realms)
+{
+ char **tmp = krb5_config_get_strings (context, NULL,
+ "domain_realm",
+ domain,
+ NULL);
+
+ if (tmp == NULL)
+ return -1;
+ *realms = tmp;
+ return 0;
+}
+
+/*
+ * This function assumes that `host' is a FQDN (and doesn't handle the
+ * special case of host == NULL either).
+ * Try to find mapping in the config file or DNS and it that fails,
+ * fall back to guessing
+ */
+
+KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
+_krb5_get_host_realm_int(krb5_context context,
+ const char *host,
+ krb5_boolean use_dns,
+ krb5_realm **realms)
+{
+ const char *p, *q;
+ const char *port;
+ char *freeme = NULL;
+ krb5_boolean dns_locate_enable;
+ krb5_error_code ret = 0;
+
+ /* Strip off any trailing ":port" suffix. */
+ port = strchr(host, ':');
+ if (port != NULL && port != host && port[1] != '\0') {
+ host = freeme = strndup(host, port - host);
+ if (host == NULL)
+ return krb5_enomem(context);
+ }
+
+ dns_locate_enable = krb5_config_get_bool_default(context, NULL, TRUE,
+ "libdefaults", "dns_lookup_realm", NULL);
+ for (p = host; p != NULL && p[0] != '\0'; p = strchr (p + 1, '.')) {
+ if (config_find_realm(context, p, realms) == 0) {
+ if (strcasecmp(*realms[0], "dns_locate") != 0)
+ break;
+ krb5_free_host_realm(context, *realms);
+ *realms = NULL;
+ if (!use_dns)
+ continue;
+ for (q = host; q != NULL; q = strchr(q + 1, '.'))
+ if (dns_find_realm(context, q, realms) == 0)
+ break;
+ if (q)
+ break;
+ } else if (use_dns && dns_locate_enable) {
+ if (dns_find_realm(context, p, realms) == 0)
+ break;
+ }
+ }
+
+ /*
+ * If 'p' is NULL, we did not find an explicit realm mapping in either the
+ * configuration file or DNS. Try the hostname suffix -upcased- as a realm
+ * as a last resort.
+ *
+ * NOTE: If we implement a KDC-specific variant of this function just for
+ * referrals, we could check whether we have a cross-realm TGT for the
+ * realm in question, and if not try the parent (loop again). Such a
+ * variant would have to have access to the HDB, naturally.
+ *
+ * We should start by adding an argument to this function that
+ * indicates whether this fallback here is desired (the KDC wouldn't
+ * desire it). Then when the KDC gets KRB5_ERR_HOST_REALM_UNKNOWN
+ * from this function, the KDC would search the HDB for cross-realm
+ * krbtgt principals that denote a hierarchical path to a realm that
+ * matches the host's domain suffix (or a suffix of it...).
+ */
+ if (p == NULL) {
+ p = strchr(host, '.');
+ if (p != NULL) {
+ p++;
+ *realms = malloc(2 * sizeof(krb5_realm));
+ if (*realms != NULL &&
+ ((*realms)[0] = strdup(p)) != NULL) {
+ strupr((*realms)[0]);
+ (*realms)[1] = NULL;
+ } else {
+ free(*realms);
+ ret = krb5_enomem(context);
+ }
+ } else {
+ krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN,
+ N_("unable to find realm of host %s", ""),
+ host);
+ ret = KRB5_ERR_HOST_REALM_UNKNOWN;
+ }
+ }
+
+ free(freeme);
+ return ret;
+}
+
+/*
+ * Return the realm(s) of `host' as a NULL-terminated list in
+ * `realms'. Free `realms' with krb5_free_host_realm().
+ */
+
+KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
+krb5_get_host_realm(krb5_context context,
+ const char *targethost,
+ krb5_realm **realms)
+{
+ const char *host = targethost;
+ char hostname[MAXHOSTNAMELEN];
+ krb5_error_code ret;
+ int use_dns;
+
+ if (host == NULL) {
+ if (gethostname (hostname, sizeof(hostname))) {
+ *realms = NULL;
+ return errno;
+ }
+ host = hostname;
+ }
+
+ /*
+ * If our local hostname is without components, don't even try to dns.
+ */
+
+ use_dns = (strchr(host, '.') != NULL);
+
+ ret = _krb5_get_host_realm_int (context, host, use_dns, realms);
+ if (ret && targethost != NULL) {
+ /*
+ * If there was no realm mapping for the host (and we wasn't
+ * looking for ourself), guess at the local realm, maybe our
+ * KDC knows better then we do and we get a referral back.
+ */
+ ret = krb5_get_default_realms(context, realms);
+ if (ret) {
+ krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN,
+ N_("Unable to find realm of host %s", ""),
+ host);
+ return KRB5_ERR_HOST_REALM_UNKNOWN;
+ }
+ }
+ return ret;
+}
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