l2tp: Call udp_sock_create

In l2tp driver call common function udp_sock_create to create the
listener UDP port.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/Kconfig

@@ -6,6 +6,7 @@ menuconfig L2TP
 	tristate "Layer Two Tunneling Protocol (L2TP)"
 	depends on (IPV6 || IPV6=n)
 	depends on INET
+	select NET_UDP_TUNNEL
 	---help---
 	  Layer Two Tunneling Protocol
 

net/l2tp/l2tp_core.c

@@ -52,6 +52,7 @@
 #include <net/dst.h>
 #include <net/ip.h>
 #include <net/udp.h>
+#include <net/udp_tunnel.h>
 #include <net/inet_common.h>
 #include <net/xfrm.h>
 #include <net/protocol.h>
@@ -1358,81 +1359,46 @@ static int l2tp_tunnel_sock_create(struct net *net,
 {
 	int err = -EINVAL;
 	struct socket *sock = NULL;
-	struct sockaddr_in udp_addr = {0};
-	struct sockaddr_l2tpip ip_addr = {0};
-#if IS_ENABLED(CONFIG_IPV6)
-	struct sockaddr_in6 udp6_addr = {0};
-	struct sockaddr_l2tpip6 ip6_addr = {0};
-#endif
+	struct udp_port_cfg udp_conf;
 
 	switch (cfg->encap) {
 	case L2TP_ENCAPTYPE_UDP:
+		memset(&udp_conf, 0, sizeof(udp_conf));
+
 #if IS_ENABLED(CONFIG_IPV6)
 		if (cfg->local_ip6 && cfg->peer_ip6) {
-			err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
-			if (err < 0)
-				goto out;
-
-			sk_change_net(sock->sk, net);
-
-			udp6_addr.sin6_family = AF_INET6;
-			memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
-			       sizeof(udp6_addr.sin6_addr));
-			udp6_addr.sin6_port = htons(cfg->local_udp_port);
-			err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
-					  sizeof(udp6_addr));
-			if (err < 0)
-				goto out;
-
-			udp6_addr.sin6_family = AF_INET6;
-			memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
-			       sizeof(udp6_addr.sin6_addr));
-			udp6_addr.sin6_port = htons(cfg->peer_udp_port);
-			err = kernel_connect(sock,
-					     (struct sockaddr *) &udp6_addr,
-					     sizeof(udp6_addr), 0);
-			if (err < 0)
-				goto out;
-
-			if (cfg->udp6_zero_tx_checksums)
-				udp_set_no_check6_tx(sock->sk, true);
-			if (cfg->udp6_zero_rx_checksums)
-				udp_set_no_check6_rx(sock->sk, true);
+			udp_conf.family = AF_INET6;
+			memcpy(&udp_conf.local_ip6, cfg->local_ip6,
+			       sizeof(udp_conf.local_ip6));
+			memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
+			       sizeof(udp_conf.peer_ip6));
+			udp_conf.use_udp6_tx_checksums =
+			    cfg->udp6_zero_tx_checksums;
+			udp_conf.use_udp6_rx_checksums =
+			    cfg->udp6_zero_rx_checksums;
 		} else
 #endif
 		{
-			err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
-			if (err < 0)
-				goto out;
+			udp_conf.family = AF_INET;
+			udp_conf.local_ip = cfg->local_ip;
+			udp_conf.peer_ip = cfg->peer_ip;
+			udp_conf.use_udp_checksums = cfg->use_udp_checksums;
+		}
 
-			sk_change_net(sock->sk, net);
+		udp_conf.local_udp_port = htons(cfg->local_udp_port);
+		udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
 
-			udp_addr.sin_family = AF_INET;
-			udp_addr.sin_addr = cfg->local_ip;
-			udp_addr.sin_port = htons(cfg->local_udp_port);
-			err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
-					  sizeof(udp_addr));
+		err = udp_sock_create(net, &udp_conf, &sock);
 		if (err < 0)
 			goto out;
 
-			udp_addr.sin_family = AF_INET;
-			udp_addr.sin_addr = cfg->peer_ip;
-			udp_addr.sin_port = htons(cfg->peer_udp_port);
-			err = kernel_connect(sock,
-					     (struct sockaddr *) &udp_addr,
-					     sizeof(udp_addr), 0);
-			if (err < 0)
-				goto out;
-		}
-
-		if (!cfg->use_udp_checksums)
-			sock->sk->sk_no_check_tx = 1;
-
 		break;
 
 	case L2TP_ENCAPTYPE_IP:
 #if IS_ENABLED(CONFIG_IPV6)
 		if (cfg->local_ip6 && cfg->peer_ip6) {
+			struct sockaddr_l2tpip6 ip6_addr = {0};
+
 			err = sock_create_kern(AF_INET6, SOCK_DGRAM,
 					  IPPROTO_L2TP, &sock);
 			if (err < 0)
@@ -1461,6 +1427,8 @@ static int l2tp_tunnel_sock_create(struct net *net,
 		} else
 #endif
 		{
+			struct sockaddr_l2tpip ip_addr = {0};
+
 			err = sock_create_kern(AF_INET, SOCK_DGRAM,
 					  IPPROTO_L2TP, &sock);
 			if (err < 0)