[NETFILTER] ctnetlink: add one nesting level for TCP state

To keep consistency, the TCP private protocol information is nested
attributes under CTA_PROTOINFO_TCP. This way the sequence of attributes to
access the TCP state information looks like here below:

CTA_PROTOINFO
CTA_PROTOINFO_TCP
CTA_PROTOINFO_TCP_STATE

instead of:

CTA_PROTOINFO
CTA_PROTOINFO_TCP_STATE
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter/nfnetlink_conntrack.h

@@ -70,11 +70,18 @@ enum ctattr_l4proto {
 
 enum ctattr_protoinfo {
 	CTA_PROTOINFO_UNSPEC,
-	CTA_PROTOINFO_TCP_STATE,
+	CTA_PROTOINFO_TCP,
 	__CTA_PROTOINFO_MAX
 };
 #define CTA_PROTOINFO_MAX (__CTA_PROTOINFO_MAX - 1)
 
+enum ctattr_protoinfo_tcp {
+	CTA_PROTOINFO_TCP_UNSPEC,
+	CTA_PROTOINFO_TCP_STATE,
+	__CTA_PROTOINFO_TCP_MAX
+};
+#define CTA_PROTOINFO_TCP_MAX (__CTA_PROTOINFO_TCP_MAX - 1)
+
 enum ctattr_counters {
 	CTA_COUNTERS_UNSPEC,
 	CTA_COUNTERS_PACKETS,

net/ipv4/netfilter/ip_conntrack_proto_tcp.c

@@ -341,11 +341,15 @@ static int tcp_print_conntrack(struct seq_file *s,
 static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa,
 			 const struct ip_conntrack *ct)
 {
+	struct nfattr *nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
+	
 	read_lock_bh(&tcp_lock);
 	NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
 		&ct->proto.tcp.state);
 	read_unlock_bh(&tcp_lock);
 
+	NFA_NEST_END(skb, nest_parms);
+
 	return 0;
 
 nfattr_failure: