keys: Break bits out of key_unlink()

Break bits out of key_unlink() into helper functions so that they can be
used in implementing key_move().

Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index ca6694ba1773f9c721765d1e9c37f0994f6c7faa..6990c7761eaab7e3050ffb3d512f46a451707a02 100644 (file)
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1382,6 +1382,65 @@ int key_link(struct key *keyring, struct key *key)
 }
 EXPORT_SYMBOL(key_link);
 
+/*
+ * Lock a keyring for unlink.
+ */
+static int __key_unlink_lock(struct key *keyring)
+       __acquires(&keyring->sem)
+{
+       if (keyring->type != &key_type_keyring)
+               return -ENOTDIR;
+
+       down_write(&keyring->sem);
+       return 0;
+}
+
+/*
+ * Begin the process of unlinking a key from a keyring.
+ */
+static int __key_unlink_begin(struct key *keyring, struct key *key,
+                             struct assoc_array_edit **_edit)
+{
+       struct assoc_array_edit *edit;
+
+       BUG_ON(*_edit != NULL);
+       
+       edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
+                                 &key->index_key);
+       if (IS_ERR(edit))
+               return PTR_ERR(edit);
+
+       if (!edit)
+               return -ENOENT;
+
+       *_edit = edit;
+       return 0;
+}
+
+/*
+ * Apply an unlink change.
+ */
+static void __key_unlink(struct key *keyring, struct key *key,
+                        struct assoc_array_edit **_edit)
+{
+       assoc_array_apply_edit(*_edit);
+       *_edit = NULL;
+       key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
+}
+
+/*
+ * Finish unlinking a key from to a keyring.
+ */
+static void __key_unlink_end(struct key *keyring,
+                            struct key *key,
+                            struct assoc_array_edit *edit)
+       __releases(&keyring->sem)
+{
+       if (edit)
+               assoc_array_cancel_edit(edit);
+       up_write(&keyring->sem);
+}
+
 /**
  * key_unlink - Unlink the first link to a key from a keyring.
  * @keyring: The keyring to remove the link from.
@@ -1401,33 +1460,20 @@ EXPORT_SYMBOL(key_link);
  */
 int key_unlink(struct key *keyring, struct key *key)
 {
-       struct assoc_array_edit *edit;
+       struct assoc_array_edit *edit = NULL;
        int ret;
 
        key_check(keyring);
        key_check(key);
 
-       if (keyring->type != &key_type_keyring)
-               return -ENOTDIR;
-
-       down_write(&keyring->sem);
-
-       edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
-                                 &key->index_key);
-       if (IS_ERR(edit)) {
-               ret = PTR_ERR(edit);
-               goto error;
-       }
-       ret = -ENOENT;
-       if (edit == NULL)
-               goto error;
-
-       assoc_array_apply_edit(edit);
-       key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
-       ret = 0;
+       ret = __key_unlink_lock(keyring);
+       if (ret < 0)
+               return ret;
 
-error:
-       up_write(&keyring->sem);
+       ret = __key_unlink_begin(keyring, key, &edit);
+       if (ret == 0)
+               __key_unlink(keyring, key, &edit);
+       __key_unlink_end(keyring, key, edit);
        return ret;
 }
 EXPORT_SYMBOL(key_unlink);