kdb: store mkey list in context and permit NULL mkey for kdb_dbe_decrypt_key_data

Previously, code needed to run a loop to find the current master key,
possibly fetch a new master key list and try finding the master key
again around each key decryption.  This was not universally done;
there are cases where only the current master key was used.  In
addition, the correct ideom for decrypting key data is too complicated
and is potentially unavailable to plugins that do not have access to
the master key.  Instead, store the master key list in the dal_handle
whenever it is fetched and permit a NULL master key for
krb5_dbe_decrypt_key_data.

* Remove APIs for krb5_db_{get|set}_mkey_list
* krb5_db_fetch_mkey_list: memoize master key list in dal_handle
* krb5_db_free_mkey_list: don't free the memoized list; arrange for it to be freed later
* krb5_dbe_decrypt_key_data: Search for correct master key on NULL argument
* change call sites to take advantage

ticket: 6778

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24314 dc483132-0cff-0310-8789-dd5450dbe970

1 files changed, 6 insertions, 59 deletions

diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c
index 4c413d07e..503c2313b 100644
--- a/src/kdc/kdc_preauth.c
+++ b/src/kdc/kdc_preauth.c
@@ -711,7 +711,7 @@ get_entry_data(krb5_context context,
     int i, k;
     krb5_data *ret;
     krb5_deltat *delta;
-    krb5_keyblock *keys, *mkey_ptr;
+    krb5_keyblock *keys;
     krb5_key_data *entry_key;
     krb5_error_code error;
     struct kdc_request_state *state = request->kdc_state;
@@ -748,32 +748,13 @@ get_entry_data(krb5_context context,
         ret->data = (char *) keys;
         ret->length = sizeof(krb5_keyblock) * (request->nktypes + 1);
         memset(ret->data, 0, ret->length);
-        if ((error = krb5_dbe_find_mkey(context, master_keylist, entry,
-                                        &mkey_ptr))) {
-            krb5_keylist_node *tmp_mkey_list;
-            /* try refreshing the mkey list in case it's been updated */
-            if (krb5_db_fetch_mkey_list(context, master_princ,
-                                        &master_keyblock, 0,
-                                        &tmp_mkey_list) == 0) {
-                krb5_dbe_free_key_list(context, master_keylist);
-                master_keylist = tmp_mkey_list;
-                if ((error = krb5_dbe_find_mkey(context, master_keylist, entry,
-                                                &mkey_ptr))) {
-                    free(ret);
-                    return (error);
-                }
-            } else {
-                free(ret);
-                return (error);
-            }
-        }
         k = 0;
         for (i = 0; i < request->nktypes; i++) {
             entry_key = NULL;
             if (krb5_dbe_find_enctype(context, entry, request->ktype[i],
                                       -1, 0, &entry_key) != 0)
                 continue;
-            if (krb5_dbe_decrypt_key_data(context, mkey_ptr, entry_key,
+            if (krb5_dbe_decrypt_key_data(context, NULL, entry_key,
                                           &keys[k], NULL) != 0) {
                 if (keys[k].contents != NULL)
                     krb5_free_keyblock_contents(context, &keys[k]);
@@ -1328,7 +1309,7 @@ return_padata(krb5_context context, krb5_db_entry *client, krb5_data *req_pkt,
     }
     key_modified = FALSE;
     null_item.contents = NULL;
-    null_item.length = NULL;
+    null_item.length = 0;
     send_pa = send_pa_list;
     *send_pa = 0;
 
@@ -1430,7 +1411,7 @@ verify_enc_timestamp(krb5_context context, krb5_db_entry *client,
     krb5_data                   scratch;
     krb5_data                   enc_ts_data;
     krb5_enc_data               *enc_data = 0;
-    krb5_keyblock               key, *mkey_ptr;
+    krb5_keyblock               key;
     krb5_key_data *             client_key;
     krb5_int32                  start;
     krb5_timestamp              timenow;
@@ -1448,24 +1429,6 @@ verify_enc_timestamp(krb5_context context, krb5_db_entry *client,
     if ((enc_ts_data.data = (char *) malloc(enc_ts_data.length)) == NULL)
         goto cleanup;
 
-    if ((retval = krb5_dbe_find_mkey(context, master_keylist, client,
-                                     &mkey_ptr))) {
-        krb5_keylist_node *tmp_mkey_list;
-        /* try refreshing the mkey list in case it's been updated */
-        if (krb5_db_fetch_mkey_list(context, master_princ,
-                                    &master_keyblock, 0,
-                                    &tmp_mkey_list) == 0) {
-            krb5_dbe_free_key_list(context, master_keylist);
-            master_keylist = tmp_mkey_list;
-            if ((retval = krb5_dbe_find_mkey(context, master_keylist, client,
-                                             &mkey_ptr))) {
-                goto cleanup;
-            }
-        } else {
-            goto cleanup;
-        }
-    }
-
     start = 0;
     decrypt_err = 0;
     while (1) {
@@ -1474,7 +1437,7 @@ verify_enc_timestamp(krb5_context context, krb5_db_entry *client,
                                               -1, 0, &client_key)))
             goto cleanup;
 
-        if ((retval = krb5_dbe_decrypt_key_data(context, mkey_ptr, client_key,
+        if ((retval = krb5_dbe_decrypt_key_data(context, NULL, client_key,
                                                 &key, NULL)))
             goto cleanup;
 
@@ -2785,22 +2748,6 @@ static krb5_error_code verify_pkinit_request(
         goto cleanup;
     }
     cert_hash_len = strlen(cert_hash);
-    if ((krtn = krb5_dbe_find_mkey(context, master_keylist, &entry, &mkey_ptr))) {
-        krb5_keylist_node *tmp_mkey_list;
-        /* try refreshing the mkey list in case it's been updated */
-        if (krb5_db_fetch_mkey_list(context, master_princ,
-                                    &master_keyblock, 0,
-                                    &tmp_mkey_list) == 0) {
-            krb5_dbe_free_key_list(context, master_keylist);
-            master_keylist = tmp_mkey_list;
-            if ((krtn = krb5_dbe_find_mkey(context, master_keylist, &entry,
-                                           &mkey_ptr))) {
-                goto cleanup;
-            }
-        } else {
-            goto cleanup;
-        }
-    }
     for(key_dex=0; key_dex<client->n_key_data; key_dex++) {
         krb5_key_data *key_data = &client->key_data[key_dex];
         kdcPkinitDebug("--- key %u type[0] %u length[0] %u type[1] %u length[1] %u\n",
@@ -2815,7 +2762,7 @@ static krb5_error_code verify_pkinit_request(
          * Unfortunately this key is stored encrypted even though it's
          * not sensitive...
          */
-        krtn = krb5_dbe_decrypt_key_data(context, mkey_ptr, key_data,
+        krtn = krb5_dbe_decrypt_key_data(context, NULL, key_data,
                                          &decrypted_key, NULL);
         if(krtn) {
             kdcPkinitDebug("verify_pkinit_request: error decrypting cert hash block\n");