netfilter: nf_tables: add support to destroy operation

Introduce NFT_MSG_DESTROY* message type. The destroy operation performs a
delete operation but ignoring the ENOENT errors.

This is useful for the transaction semantics, where failing to delete an
object which does not exist results in aborting the transaction.

This new command allows the transaction to proceed in case the object
does not exist.
Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

include/uapi/linux/netfilter/nf_tables.h

@@ -98,6 +98,13 @@ enum nft_verdicts {
  * @NFT_MSG_GETFLOWTABLE: get flow table (enum nft_flowtable_attributes)
  * @NFT_MSG_DELFLOWTABLE: delete flow table (enum nft_flowtable_attributes)
  * @NFT_MSG_GETRULE_RESET: get rules and reset stateful expressions (enum nft_obj_attributes)
+ * @NFT_MSG_DESTROYTABLE: destroy a table (enum nft_table_attributes)
+ * @NFT_MSG_DESTROYCHAIN: destroy a chain (enum nft_chain_attributes)
+ * @NFT_MSG_DESTROYRULE: destroy a rule (enum nft_rule_attributes)
+ * @NFT_MSG_DESTROYSET: destroy a set (enum nft_set_attributes)
+ * @NFT_MSG_DESTROYSETELEM: destroy a set element (enum nft_set_elem_attributes)
+ * @NFT_MSG_DESTROYOBJ: destroy a stateful object (enum nft_object_attributes)
+ * @NFT_MSG_DESTROYFLOWTABLE: destroy flow table (enum nft_flowtable_attributes)
  */
 enum nf_tables_msg_types {
 	NFT_MSG_NEWTABLE,
@@ -126,6 +133,13 @@ enum nf_tables_msg_types {
 	NFT_MSG_GETFLOWTABLE,
 	NFT_MSG_DELFLOWTABLE,
 	NFT_MSG_GETRULE_RESET,
+	NFT_MSG_DESTROYTABLE,
+	NFT_MSG_DESTROYCHAIN,
+	NFT_MSG_DESTROYRULE,
+	NFT_MSG_DESTROYSET,
+	NFT_MSG_DESTROYSETELEM,
+	NFT_MSG_DESTROYOBJ,
+	NFT_MSG_DESTROYFLOWTABLE,
 	NFT_MSG_MAX,
 };