netfilter: nf_tables: support for multiple devices per netdev hook

This patch allows you to register one netdev basechain to multiple
devices. This adds a new NFTA_HOOK_DEVS netlink attribute to specify
the list of netdevices. Basechains store a list of hooks.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: ummakynes

include/net/netfilter/nf_tables.h

@@ -973,21 +973,21 @@ struct nft_hook {
  *	struct nft_base_chain - nf_tables base chain
  *
  *	@ops: netfilter hook ops
+ *	@hook_list: list of netfilter hooks (for NFPROTO_NETDEV family)
  *	@type: chain type
  *	@policy: default policy
  *	@stats: per-cpu chain stats
  *	@chain: the chain
- *	@dev_name: device name that this base chain is attached to (if any)
  *	@flow_block: flow block (for hardware offload)
  */
 struct nft_base_chain {
 	struct nf_hook_ops		ops;
+	struct list_head		hook_list;
 	const struct nft_chain_type	*type;
 	u8				policy;
 	u8				flags;
 	struct nft_stats __percpu	*stats;
 	struct nft_chain		chain;
-	char 				dev_name[IFNAMSIZ];
 	struct flow_block		flow_block;
 };
 

include/uapi/linux/netfilter/nf_tables.h

@@ -144,12 +144,14 @@ enum nft_list_attributes {
  * @NFTA_HOOK_HOOKNUM: netfilter hook number (NLA_U32)
  * @NFTA_HOOK_PRIORITY: netfilter hook priority (NLA_U32)
  * @NFTA_HOOK_DEV: netdevice name (NLA_STRING)
+ * @NFTA_HOOK_DEVS: list of netdevices (NLA_NESTED)
  */
 enum nft_hook_attributes {
 	NFTA_HOOK_UNSPEC,
 	NFTA_HOOK_HOOKNUM,
 	NFTA_HOOK_PRIORITY,
 	NFTA_HOOK_DEV,
+	NFTA_HOOK_DEVS,
 	__NFTA_HOOK_MAX
 };
 #define NFTA_HOOK_MAX		(__NFTA_HOOK_MAX - 1)