netfilter: add missing IS_ENABLED(CONFIG_NF_CONNTRACK) checks to some header-files.

struct nf_conn contains a "struct nf_conntrack ct_general" member and
struct net contains a "struct netns_ct ct" member which are both only
defined in CONFIG_NF_CONNTRACK is enabled. These members are used in a
number of inline functions defined in other header-files. Added
preprocessor checks to make sure the headers will compile if
CONFIG_NF_CONNTRACK is disabled.

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

include/net/netfilter/nf_conntrack.h

···
 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
 
 struct nf_conn {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	/* Usage count in here is 1 for hash table, 1 per skb,
 	 * plus 1 for any connection(s) we are `master' for
 	 *
···
 	 * beware nf_ct_get() is different and don't inc refcnt.
 	 */
 	struct nf_conntrack ct_general;
+#endif
 
 	spinlock_t	lock;
 	/* jiffies32 when this ct is considered dead */
···
 int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 			     const struct nf_conn *ignored_conntrack);
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+
 #define NFCT_INFOMASK	7UL
 #define NFCT_PTRMASK	~(NFCT_INFOMASK)
 
···
 	WARN_ON(!ct);
 	nf_conntrack_put(&ct->ct_general);
 }
+
+#endif
 
 /* Protocol module loading */
 int nf_ct_l3proto_try_module_get(unsigned short l3proto);
···
 
 u32 nf_ct_get_id(const struct nf_conn *ct);
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+
 static inline void
 nf_ct_set(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info info)
 {
 	skb->_nfct = (unsigned long)ct | info;
 }
+
+#endif
 
 #define NF_CT_STAT_INC(net, count)	  __this_cpu_inc((net)->ct.stat->count)
 #define NF_CT_STAT_INC_ATOMIC(net, count) this_cpu_inc((net)->ct.stat->count)

include/net/netfilter/nf_conntrack_acct.h

···
 static inline
 struct nf_conn_acct *nf_ct_acct_ext_add(struct nf_conn *ct, gfp_t gfp)
 {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	struct net *net = nf_ct_net(ct);
 	struct nf_conn_acct *acct;
 
···
 
 
 	return acct;
+#else
+	return NULL;
+#endif
 };
 
 /* Check if connection tracking accounting is enabled */
 static inline bool nf_ct_acct_enabled(struct net *net)
 {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	return net->ct.sysctl_acct != 0;
+#else
+	return false;
+#endif
 }
 
 /* Enable/disable connection tracking accounting */
 static inline void nf_ct_set_acct(struct net *net, bool enable)
 {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	net->ct.sysctl_acct = enable;
+#endif
 }
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 void nf_conntrack_acct_pernet_init(struct net *net);
 
 int nf_conntrack_acct_init(void);
 void nf_conntrack_acct_fini(void);
+#endif /* IS_ENABLED(CONFIG_NF_CONNTRACK) */
+
 #endif /* _NF_CONNTRACK_ACCT_H */

include/net/netfilter/nf_conntrack_l4proto.h

···
 			       const char *fmt, ...) { }
 #endif /* CONFIG_SYSCTL */
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 static inline struct nf_generic_net *nf_generic_pernet(struct net *net)
 {
        return &net->ct.nf_ct_proto.generic;
···
 {
        return &net->ct.nf_ct_proto.icmpv6;
 }
+#endif
 
 #ifdef CONFIG_NF_CT_PROTO_DCCP
 static inline struct nf_dccp_net *nf_dccp_pernet(struct net *net)

include/net/netfilter/nf_conntrack_timestamp.h

···
 
 static inline bool nf_ct_tstamp_enabled(struct net *net)
 {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	return net->ct.sysctl_tstamp != 0;
+#else
+	return false;
+#endif
 }
 
 static inline void nf_ct_set_tstamp(struct net *net, bool enable)
 {
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 	net->ct.sysctl_tstamp = enable;
+#endif
 }
 
 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP