udp: Set NULL to sk->sk_prot->h.udp_table.

We will soon introduce an optional per-netns hash table
for UDP.

This means we cannot use the global sk->sk_prot->h.udp_table
to fetch a UDP hash table.

Instead, set NULL to sk->sk_prot->h.udp_table for UDP and get
a proper table from net->ipv4.udp_table.

Note that we still need sk->sk_prot->h.udp_table for UDP LITE.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv4.h

@@ -43,6 +43,7 @@ struct tcp_fastopen_context;
 
 struct netns_ipv4 {
 	struct inet_timewait_death_row tcp_death_row;
+	struct udp_table *udp_table;
 
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header	*forw_hdr;

net/ipv4/udp.c

@@ -131,6 +131,11 @@ EXPORT_PER_CPU_SYMBOL_GPL(udp_memory_per_cpu_fw_alloc);
 #define MAX_UDP_PORTS 65536
 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
 
+static struct udp_table *udp_get_table_prot(struct sock *sk)
+{
+	return sk->sk_prot->h.udp_table ? : sock_net(sk)->ipv4.udp_table;
+}
+
 static int udp_lib_lport_inuse(struct net *net, __u16 num,
 			       const struct udp_hslot *hslot,
 			       unsigned long *bitmap,
@@ -232,7 +237,7 @@ static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot)
 int udp_lib_get_port(struct sock *sk, unsigned short snum,
 		     unsigned int hash2_nulladdr)
 {
-	struct udp_table *udptable = sk->sk_prot->h.udp_table;
+	struct udp_table *udptable = udp_get_table_prot(sk);
 	struct udp_hslot *hslot, *hslot2;
 	struct net *net = sock_net(sk);
 	int error = 1;
@@ -1999,7 +2004,7 @@ EXPORT_SYMBOL(udp_disconnect);
 void udp_lib_unhash(struct sock *sk)
 {
 	if (sk_hashed(sk)) {
-		struct udp_table *udptable = sk->sk_prot->h.udp_table;
+		struct udp_table *udptable = udp_get_table_prot(sk);
 		struct udp_hslot *hslot, *hslot2;
 
 		hslot  = udp_hashslot(udptable, sock_net(sk),
@@ -2030,7 +2035,7 @@ EXPORT_SYMBOL(udp_lib_unhash);
 void udp_lib_rehash(struct sock *sk, u16 newhash)
 {
 	if (sk_hashed(sk)) {
-		struct udp_table *udptable = sk->sk_prot->h.udp_table;
+		struct udp_table *udptable = udp_get_table_prot(sk);
 		struct udp_hslot *hslot, *hslot2, *nhslot2;
 
 		hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
@@ -2967,7 +2972,7 @@ struct proto udp_prot = {
 	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_udp_wmem_min),
 	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_udp_rmem_min),
 	.obj_size		= sizeof(struct udp_sock),
-	.h.udp_table		= &udp_table,
+	.h.udp_table		= NULL,
 	.diag_destroy		= udp_abort,
 };
 EXPORT_SYMBOL(udp_prot);
@@ -3280,6 +3285,8 @@ EXPORT_SYMBOL(udp_flow_hashrnd);
 
 static int __net_init udp_sysctl_init(struct net *net)
 {
+	net->ipv4.udp_table = &udp_table;
+
 	net->ipv4.sysctl_udp_rmem_min = PAGE_SIZE;
 	net->ipv4.sysctl_udp_wmem_min = PAGE_SIZE;
 

net/ipv6/udp.c

@@ -1774,7 +1774,7 @@ struct proto udpv6_prot = {
 	.sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
 	.sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
 	.obj_size		= sizeof(struct udp6_sock),
-	.h.udp_table		= &udp_table,
+	.h.udp_table		= NULL,
 	.diag_destroy		= udp_abort,
 };