netfilter: nf_conntrack: generalize nf_ct_l4proto_net

This patch generalizes nf_ct_l4proto_net by splitting it into chunks and
moving the corresponding protocol part to where it really belongs to.

To clarify, note that we follow two different approaches to support per-net
depending if it's built-in or run-time loadable protocol tracker.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Gao feng <gaofeng@cn.fujitsu.com>

include/net/netfilter/nf_conntrack_l4proto.h

@@ -99,6 +99,9 @@ struct nf_conntrack_l4proto {
 	/* Init l4proto pernet data */
 	int (*init_net)(struct net *net, u_int16_t proto);
 
+	/* Return the per-net protocol part. */
+	struct nf_proto_net *(*get_net_proto)(struct net *net);
+
 	/* Protocol name */
 	const char *name;
 

net/ipv4/netfilter/nf_conntrack_proto_icmp.c

@@ -388,6 +388,11 @@ static int icmp_init_net(struct net *net, u_int16_t proto)
 	return ret;
 }
 
+static struct nf_proto_net *icmp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.icmp.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
 {
 	.l3proto		= PF_INET,
@@ -418,4 +423,5 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= icmp_init_net,
+	.get_net_proto		= icmp_get_net_proto,
 };

net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

@@ -358,6 +358,11 @@ static int icmpv6_init_net(struct net *net, u_int16_t proto)
 	return icmpv6_kmemdup_sysctl_table(pn, in);
 }
 
+static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.icmpv6.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 {
 	.l3proto		= PF_INET6,
@@ -386,4 +391,5 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= icmpv6_init_net,
+	.get_net_proto		= icmpv6_get_net_proto,
 };

net/netfilter/nf_conntrack_proto.c

@@ -303,22 +303,12 @@ EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_unregister);
 static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
 					      struct nf_conntrack_l4proto *l4proto)
 {
-	switch (l4proto->l4proto) {
-	case IPPROTO_TCP:
-		return (struct nf_proto_net *)&net->ct.nf_ct_proto.tcp;
-	case IPPROTO_UDP:
-		return (struct nf_proto_net *)&net->ct.nf_ct_proto.udp;
-	case IPPROTO_ICMP:
-		return (struct nf_proto_net *)&net->ct.nf_ct_proto.icmp;
-	case IPPROTO_ICMPV6:
-		return (struct nf_proto_net *)&net->ct.nf_ct_proto.icmpv6;
-	case 255: /* l4proto_generic */
-		return (struct nf_proto_net *)&net->ct.nf_ct_proto.generic;
-	default:
-		if (l4proto->net_id)
-			return net_generic(net, *l4proto->net_id);
-		else
-			return NULL;
+	if (l4proto->get_net_proto) {
+		/* statically built-in protocols use static per-net */
+		return l4proto->get_net_proto(net);
+	} else if (l4proto->net_id) {
+		/* ... and loadable protocols use dynamic per-net */
+		return net_generic(net, *l4proto->net_id);
 	}
 	return NULL;
 }

net/netfilter/nf_conntrack_proto_generic.c

@@ -186,6 +186,11 @@ static int generic_init_net(struct net *net, u_int16_t proto)
 	return ret;
 }
 
+static struct nf_proto_net *generic_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.generic.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_generic __read_mostly =
 {
 	.l3proto		= PF_UNSPEC,
@@ -207,4 +212,5 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_generic __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= generic_init_net,
+	.get_net_proto		= generic_get_net_proto,
 };

net/netfilter/nf_conntrack_proto_tcp.c

@@ -1623,6 +1623,11 @@ static int tcp_init_net(struct net *net, u_int16_t proto)
 	return ret;
 }
 
+static struct nf_proto_net *tcp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.tcp.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
 {
 	.l3proto		= PF_INET,
@@ -1656,6 +1661,7 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp4 __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= tcp_init_net,
+	.get_net_proto		= tcp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp4);
 
@@ -1692,5 +1698,6 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp6 __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= tcp_init_net,
+	.get_net_proto		= tcp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_tcp6);

net/netfilter/nf_conntrack_proto_udp.c

@@ -297,6 +297,11 @@ static int udp_init_net(struct net *net, u_int16_t proto)
 	return ret;
 }
 
+static struct nf_proto_net *udp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.udp.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 {
 	.l3proto		= PF_INET,
@@ -325,6 +330,7 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= udp_init_net,
+	.get_net_proto		= udp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 
@@ -356,5 +362,6 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= udp_init_net,
+	.get_net_proto		= udp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);