krb5_error_code
_kdc_find_etype(krb5_context context, const hdb_entry_ex *princ,
krb5_enctype *etypes, unsigned len,
Key **ret_key, krb5_enctype *ret_etype)
{
int i;
krb5_error_code ret = KRB5KDC_ERR_ETYPE_NOSUPP;
krb5_salt def_salt;
krb5_get_pw_salt (context, princ->entry.principal, &def_salt);
for(i = 0; ret != 0 && i < len ; i++) {
Key *key = NULL;
if (krb5_enctype_valid(context, etypes[i]) != 0 &&
!_kdc_is_weak_exception(princ->entry.principal, etypes[i]))
continue;
while (hdb_next_enctype2key(context, &princ->entry, etypes[i], &key) == 0) {
if (key->key.keyvalue.length == 0) {
ret = KRB5KDC_ERR_NULL_KEY;
continue;
}
*ret_key = key;
*ret_etype = etypes[i];
ret = 0;
if (is_default_salt_p(&def_salt, key)) {
krb5_free_salt (context, def_salt);
return ret;
}
}
}
krb5_free_salt (context, def_salt);
return ret;
}
krb5_error_code
_kdc_get_preferred_key(krb5_context context,
krb5_kdc_configuration *config,
hdb_entry_ex *h,
const char *name,
krb5_enctype *enctype,
Key **key)
{
krb5_error_code ret;
int i;
if (config->use_strongest_server_key) {
const krb5_enctype *p = krb5_kerberos_enctypes(context);
for (i = 0; p[i] != (krb5_enctype)ETYPE_NULL; i++) {
if (krb5_enctype_valid(context, p[i]) != 0 &&
!_kdc_is_weak_exception(h->entry.principal, p[i]))
continue;
ret = hdb_enctype2key(context, &h->entry, NULL, p[i], key);
if (ret != 0)
continue;
if (enctype != NULL)
*enctype = p[i];
return 0;
}
} else {
*key = NULL;
for (i = 0; i < h->entry.keys.len; i++) {
if (krb5_enctype_valid(context, h->entry.keys.val[i].key.keytype) != 0 &&
!_kdc_is_weak_exception(h->entry.principal, h->entry.keys.val[i].key.keytype))
continue;
ret = hdb_enctype2key(context, &h->entry, NULL,
h->entry.keys.val[i].key.keytype, key);
if (ret != 0)
continue;
if (enctype != NULL)
*enctype = (*key)->key.keytype;
return 0;
}
}
krb5_set_error_message(context, EINVAL,
"No valid kerberos key found for %s", name);
return EINVAL; /* XXX */
}
krb5_error_code
_kdc_find_etype(krb5_context context, krb5_boolean use_strongest_session_key,
krb5_boolean is_preauth, hdb_entry_ex *princ,
krb5_enctype *etypes, unsigned len,
krb5_enctype *ret_enctype, Key **ret_key)
{
krb5_error_code ret;
krb5_salt def_salt;
krb5_enctype enctype = ETYPE_NULL;
Key *key;
int i;
/* We'll want to avoid keys with v4 salted keys in the pre-auth case... */
ret = krb5_get_pw_salt(context, princ->entry.principal, &def_salt);
if (ret)
return ret;
ret = KRB5KDC_ERR_ETYPE_NOSUPP;
if (use_strongest_session_key) {
const krb5_enctype *p;
krb5_enctype clientbest = ETYPE_NULL;
int j;
/*
* Pick the strongest key that the KDC, target service, and
* client all support, using the local cryptosystem enctype
* list in strongest-to-weakest order to drive the search.
*
* This is not what RFC4120 says to do, but it encourages
* adoption of stronger enctypes. This doesn't play well with
* clients that have multiple Kerberos client implementations
* available with different supported enctype lists.
*/
/* drive the search with local supported enctypes list */
p = krb5_kerberos_enctypes(context);
for (i = 0; p[i] != ETYPE_NULL && enctype == ETYPE_NULL; i++) {
if (krb5_enctype_valid(context, p[i]) != 0)
continue;
/* check that the client supports it too */
for (j = 0; j < len && enctype == ETYPE_NULL; j++) {
if (p[i] != etypes[j])
continue;
/* save best of union of { client, crypto system } */
if (clientbest == ETYPE_NULL)
clientbest = p[i];
/* check target princ support */
ret = hdb_enctype2key(context, &princ->entry, p[i], &key);
if (ret)
continue;
if (is_preauth && !is_default_salt_p(&def_salt, key))
continue;
enctype = p[i];
}
}
if (clientbest != ETYPE_NULL && enctype == ETYPE_NULL)
enctype = clientbest;
else if (enctype == ETYPE_NULL)
ret = KRB5KDC_ERR_ETYPE_NOSUPP;
if (ret == 0 && ret_enctype != NULL)
*ret_enctype = enctype;
if (ret == 0 && ret_key != NULL)
*ret_key = key;
} else {
/*
* Pick the first key from the client's enctype list that is
* supported by the cryptosystem and by the given principal.
*
* RFC4120 says we SHOULD pick the first _strong_ key from the
* client's list... not the first key... If the admin disallows
* weak enctypes in krb5.conf and selects this key selection
* algorithm, then we get exactly what RFC4120 says.
*/
for(key = NULL, i = 0; ret != 0 && i < len; i++, key = NULL) {
if (krb5_enctype_valid(context, etypes[i]) != 0 &&
!_kdc_is_weak_exception(princ->entry.principal, etypes[i]))
continue;
while (hdb_next_enctype2key(context, &princ->entry, etypes[i], &key) == 0) {
if (key->key.keyvalue.length == 0) {
ret = KRB5KDC_ERR_NULL_KEY;
continue;
}
if (ret_key != NULL)
*ret_key = key;
if (ret_enctype != NULL)
*ret_enctype = etypes[i];
ret = 0;
if (is_preauth && is_default_salt_p(&def_salt, key))
goto out;
}
}
}
out:
krb5_free_salt (context, def_salt);
return ret;
}
