netfilter: remove CONFIG_NETFILTER checks from headers.

`struct nf_hook_ops`, `struct nf_hook_state` and the `nf_hookfn`
function typedef appear in function and struct declarations and
definitions in a number of netfilter headers. The structs and typedef
themselves are defined by linux/netfilter.h but only when
CONFIG_NETFILTER is enabled. Define them unconditionally and add
forward declarations in order to remove CONFIG_NETFILTER conditionals
from the other headers.

Signed-off-by: Jeremy Sowden <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

include/linux/netfilter.h

···
 #include <linux/netdevice.h>
 #include <net/net_namespace.h>
 
-#ifdef CONFIG_NETFILTER
 static inline int NF_DROP_GETERR(int verdict)
 {
 	return -(verdict >> NF_VERDICT_QBITS);
···
 	 */
 };
 
+#ifdef CONFIG_NETFILTER
 static inline struct nf_hook_ops **nf_hook_entries_get_hook_ops(const struct nf_hook_entries *e)
 {
 	unsigned int n = e->num_hook_entries;

include/linux/netfilter/x_tables.h

···
 	union {
 		const void *matchinfo, *targinfo;
 	};
-#if IS_ENABLED(CONFIG_NETFILTER)
 	const struct nf_hook_state *state;
-#endif
 	int fragoff;
 	unsigned int thoff;
 	bool hotdrop;
 };
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 static inline struct net *xt_net(const struct xt_action_param *par)
 {
 	return par->state->net;
···
 {
 	return par->state->pf;
 }
-#endif
 
 /**
  * struct xt_mtchk_param - parameters for match extensions'
···
 	return cnt;
 }
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);
-#endif
 
 #ifdef CONFIG_COMPAT
 #include <net/compat.h>

include/linux/netfilter_arp/arp_tables.h

···
 }
 
 extern void *arpt_alloc_initial_table(const struct xt_table *);
-#if IS_ENABLED(CONFIG_NETFILTER)
 int arpt_register_table(struct net *net, const struct xt_table *table,
 			const struct arpt_replace *repl,
 			const struct nf_hook_ops *ops, struct xt_table **res);
···
 extern unsigned int arpt_do_table(struct sk_buff *skb,
 				  const struct nf_hook_state *state,
 				  struct xt_table *table);
-#endif
 
 #ifdef CONFIG_COMPAT
 #include <net/compat.h>

include/linux/netfilter_bridge/ebtables.h

···
 
 #define EBT_ALIGN(s) (((s) + (__alignof__(struct _xt_align)-1)) & \
 		     ~(__alignof__(struct _xt_align)-1))
-#if IS_ENABLED(CONFIG_NETFILTER)
+
 extern int ebt_register_table(struct net *net,
 			      const struct ebt_table *table,
 			      const struct nf_hook_ops *ops,
···
 extern unsigned int ebt_do_table(struct sk_buff *skb,
 				 const struct nf_hook_state *state,
 				 struct ebt_table *table);
-#endif
 
 /* True if the hook mask denotes that the rule is in a base chain,
  * used in the check() functions */

include/linux/netfilter_ipv4/ip_tables.h

···
 
 #include <linux/if.h>
 #include <linux/in.h>
+#include <linux/init.h>
 #include <linux/ip.h>
 #include <linux/skbuff.h>
-
-#include <linux/init.h>
 #include <uapi/linux/netfilter_ipv4/ip_tables.h>
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int ipt_register_table(struct net *net, const struct xt_table *table,
 		       const struct ipt_replace *repl,
 		       const struct nf_hook_ops *ops, struct xt_table **res);
 void ipt_unregister_table(struct net *net, struct xt_table *table,
 			  const struct nf_hook_ops *ops);
-#endif
 
 /* Standard entry. */
 struct ipt_standard {
···
 }
 
 extern void *ipt_alloc_initial_table(const struct xt_table *);
-#if IS_ENABLED(CONFIG_NETFILTER)
 extern unsigned int ipt_do_table(struct sk_buff *skb,
 				 const struct nf_hook_state *state,
 				 struct xt_table *table);
-#endif
 
 #ifdef CONFIG_COMPAT
 #include <net/compat.h>

include/linux/netfilter_ipv6/ip6_tables.h

···
 
 #include <linux/if.h>
 #include <linux/in6.h>
+#include <linux/init.h>
 #include <linux/ipv6.h>
 #include <linux/skbuff.h>
-
-#include <linux/init.h>
 #include <uapi/linux/netfilter_ipv6/ip6_tables.h>
 
 extern void *ip6t_alloc_initial_table(const struct xt_table *);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int ip6t_register_table(struct net *net, const struct xt_table *table,
 			const struct ip6t_replace *repl,
 			const struct nf_hook_ops *ops, struct xt_table **res);
···
 extern unsigned int ip6t_do_table(struct sk_buff *skb,
 				  const struct nf_hook_state *state,
 				  struct xt_table *table);
-#endif
 
 #ifdef CONFIG_COMPAT
 #include <net/compat.h>

include/net/netfilter/br_netfilter.h

···
 struct net_device *setup_pre_routing(struct sk_buff *skb,
 				     const struct net *net);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 #if IS_ENABLED(CONFIG_IPV6)
 int br_validate_ipv6(struct net *net, struct sk_buff *skb);
 unsigned int br_nf_pre_routing_ipv6(void *priv,
···
 {
 	return NF_ACCEPT;
 }
-#endif
 #endif
 
 #endif /* _BR_NETFILTER_H_ */

include/net/netfilter/nf_conntrack_bridge.h

···
 #include <linux/types.h>
 #include <uapi/linux/if_ether.h>
 
+struct nf_hook_ops;
+
 struct nf_ct_bridge_info {
-#if IS_ENABLED(CONFIG_NETFILTER)
 	struct nf_hook_ops	*ops;
-#endif
 	unsigned int		ops_size;
 	struct module		*me;
 };

include/net/netfilter/nf_conntrack_core.h

···
    standalone connection tracking module, and the compatibility layer's use
    of connection tracking. */
 
-#if IS_ENABLED(CONFIG_NETFILTER)
-unsigned int nf_conntrack_in(struct sk_buff *skb, const struct nf_hook_state *state);
-#endif
+unsigned int nf_conntrack_in(struct sk_buff *skb,
+			     const struct nf_hook_state *state);
 
 int nf_conntrack_init_net(struct net *net);
 void nf_conntrack_cleanup_net(struct net *net);

include/net/netfilter/nf_conntrack_l4proto.h

···
 bool nf_conntrack_invert_icmpv6_tuple(struct nf_conntrack_tuple *tuple,
 				      const struct nf_conntrack_tuple *orig);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int nf_conntrack_inet_error(struct nf_conn *tmpl, struct sk_buff *skb,
 			    unsigned int dataoff,
 			    const struct nf_hook_state *state,
···
 			    unsigned int dataoff,
 			    enum ip_conntrack_info ctinfo,
 			    const struct nf_hook_state *state);
-#endif
 
 void nf_conntrack_generic_init_net(struct net *net);
 void nf_conntrack_tcp_init_net(struct net *net);

include/net/netfilter/nf_conntrack_tuple.h

···
 	struct nf_conntrack_tuple tuple;
 };
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 static inline bool __nf_ct_tuple_src_equal(const struct nf_conntrack_tuple *t1,
 					   const struct nf_conntrack_tuple *t2)
 {
···
 	return nf_ct_tuple_src_mask_cmp(t, tuple, mask) &&
 	       __nf_ct_tuple_dst_equal(t, tuple);
 }
-#endif
 
 #endif /* _NF_CONNTRACK_TUPLE_H */

include/net/netfilter/nf_flow_table.h

···
 	int				family;
 	int				(*init)(struct nf_flowtable *ft);
 	void				(*free)(struct nf_flowtable *ft);
-#if IS_ENABLED(CONFIG_NETFILTER)
 	nf_hookfn			*hook;
-#endif
 	struct module			*owner;
 };
 
···
 	__be16 source, dest;
 };
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 unsigned int nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
 				     const struct nf_hook_state *state);
 unsigned int nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 				       const struct nf_hook_state *state);
-#endif
 
 #define MODULE_ALIAS_NF_FLOWTABLE(family)	\
 	MODULE_ALIAS("nf-flowtable-" __stringify(family))

include/net/netfilter/nf_nat.h

···
 #endif
 }
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
 		       const struct nf_hook_ops *nat_ops, unsigned int ops_count);
 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
 			  unsigned int ops_count);
-#endif
 
 unsigned int nf_nat_packet(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 			   unsigned int hooknum, struct sk_buff *skb);
···
 				    enum ip_conntrack_info ctinfo,
 				    unsigned int hooknum, unsigned int hdrlen);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops);
 void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
 
···
 unsigned int
 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
 	       const struct nf_hook_state *state);
-#endif
 
 int nf_xfrm_me_harder(struct net *n, struct sk_buff *s, unsigned int family);
 

include/net/netfilter/nf_queue.h

···
 	unsigned int		id;
 	unsigned int		hook_index;	/* index in hook_entries->hook[] */
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 	struct nf_hook_state	state;
-#endif
 	u16			size; /* sizeof(entry) + saved route keys */
 
 	/* extra space to store route keys */
···
 	return queue;
 }
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
 	     unsigned int index, unsigned int verdict);
-#endif
 
 #endif /* _NF_QUEUE_H */

include/net/netfilter/nf_synproxy.h

···
 			      const struct tcphdr *th,
 			      struct synproxy_options *opts, u32 recv_seq);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
+struct nf_hook_state;
+
 unsigned int ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
 				const struct nf_hook_state *nhs);
-#endif
 int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net);
 void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net);
 
···
 				   const struct tcphdr *th,
 				   struct synproxy_options *opts, u32 recv_seq);
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 unsigned int ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
 				const struct nf_hook_state *nhs);
-#endif
 int nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net);
 void nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net);
 #else

include/net/netfilter/nf_tables.h

···
 	struct xt_action_param		xt;
 };
 
-#if IS_ENABLED(CONFIG_NETFILTER)
 static inline struct net *nft_net(const struct nft_pktinfo *pkt)
 {
 	return pkt->xt.state->net;
···
 	pkt->skb = skb;
 	pkt->xt.state = state;
 }
-#endif
 
 static inline void nft_set_pktinfo_unspec(struct nft_pktinfo *pkt,
 					  struct sk_buff *skb)
···
 	int				family;
 	struct module			*owner;
 	unsigned int			hook_mask;
-#if IS_ENABLED(CONFIG_NETFILTER)
 	nf_hookfn			*hooks[NF_MAX_HOOKS];
 	int				(*ops_register)(struct net *net, const struct nf_hook_ops *ops);
 	void				(*ops_unregister)(struct net *net, const struct nf_hook_ops *ops);
-#endif
 };
 
 int nft_chain_validate_dependency(const struct nft_chain *chain,
···
  *	@flow_block: flow block (for hardware offload)
  */
 struct nft_base_chain {
-#if IS_ENABLED(CONFIG_NETFILTER)
 	struct nf_hook_ops		ops;
-#endif
 	const struct nft_chain_type	*type;
 	u8				policy;
 	u8				flags;
···
 					use:30;
 	u64				handle;
 	/* runtime data below here */
-#if IS_ENABLED(CONFIG_NETFILTER)
 	struct nf_hook_ops		*ops ____cacheline_aligned;
-#endif
 	struct nf_flowtable		data;
 };