KEYS: Provide a generic instantiation function

Provide a generic instantiation function for key types that use the preparse
hook.  This makes it easier to prereserve key quota before keyrings get locked
to retain the new key.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>

crypto/asymmetric_keys/asymmetric_type.c

@@ -163,29 +163,6 @@ static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
 	kfree(prep->description);
 }
 
-/*
- * Instantiate a asymmetric_key defined key.  The key was preparsed, so we just
- * have to transfer the data here.
- */
-static int asymmetric_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
-{
-	int ret;
-
-	pr_devel("==>%s()\n", __func__);
-
-	ret = key_payload_reserve(key, prep->quotalen);
-	if (ret == 0) {
-		key->type_data.p[0] = prep->type_data[0];
-		key->type_data.p[1] = prep->type_data[1];
-		key->payload.data = prep->payload;
-		prep->type_data[0] = NULL;
-		prep->type_data[1] = NULL;
-		prep->payload = NULL;
-	}
-	pr_devel("<==%s() = %d\n", __func__, ret);
-	return ret;
-}
-
 /*
  * dispose of the data dangling from the corpse of a asymmetric key
  */
@@ -205,7 +182,7 @@ struct key_type key_type_asymmetric = {
 	.name		= "asymmetric",
 	.preparse	= asymmetric_key_preparse,
 	.free_preparse	= asymmetric_key_free_preparse,
-	.instantiate	= asymmetric_key_instantiate,
+	.instantiate	= generic_key_instantiate,
 	.match		= asymmetric_key_match,
 	.destroy	= asymmetric_key_destroy,
 	.describe	= asymmetric_key_describe,

include/linux/key-type.h

@@ -159,5 +159,7 @@ static inline int key_negate_and_link(struct key *key,
 	return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
 }
 
+extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
+
 #endif /* CONFIG_KEYS */
 #endif /* _LINUX_KEY_TYPE_H */

security/keys/key.c

@@ -1023,6 +1023,36 @@ void key_invalidate(struct key *key)
 }
 EXPORT_SYMBOL(key_invalidate);
 
+/**
+ * generic_key_instantiate - Simple instantiation of a key from preparsed data
+ * @key: The key to be instantiated
+ * @prep: The preparsed data to load.
+ *
+ * Instantiate a key from preparsed data.  We assume we can just copy the data
+ * in directly and clear the old pointers.
+ *
+ * This can be pointed to directly by the key type instantiate op pointer.
+ */
+int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+	int ret;
+
+	pr_devel("==>%s()\n", __func__);
+
+	ret = key_payload_reserve(key, prep->quotalen);
+	if (ret == 0) {
+		key->type_data.p[0] = prep->type_data[0];
+		key->type_data.p[1] = prep->type_data[1];
+		rcu_assign_keypointer(key, prep->payload);
+		prep->type_data[0] = NULL;
+		prep->type_data[1] = NULL;
+		prep->payload = NULL;
+	}
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+EXPORT_SYMBOL(generic_key_instantiate);
+
 /**
  * register_key_type - Register a type of key.
  * @ktype: The new key type.