Merge branch 'net-enable-udp-v6-sockets-receiving-v4-packets-with-udp'

Xin Long says:

====================
net: enable udp v6 sockets receiving v4 packets with UDP

Currently, udp v6 socket can not process v4 packets with UDP GRO, as
udp_encap_needed_key is not increased when udp_tunnel_encap_enable()
is called for v6 socket.

This patchset is to increase it and remove the unnecessary code in
bareudp in Patch 1/2, and improve rxrpc encap_enable by calling
udp_tunnel_encap_enable().
====================

Link: https://lore.kernel.org/r/cover.1612342376.git.lucien.xin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bareudp.c

@@ -240,12 +240,6 @@ static int bareudp_socket_create(struct bareudp_dev *bareudp, __be16 port)
 	tunnel_cfg.encap_destroy = NULL;
 	setup_udp_tunnel_sock(bareudp->net, sock, &tunnel_cfg);
 
-	/* As the setup_udp_tunnel_sock does not call udp_encap_enable if the
-	 * socket type is v6 an explicit call to udp_encap_enable is needed.
-	 */
-	if (sock->sk->sk_family == AF_INET6)
-		udp_encap_enable();
-
 	rcu_assign_pointer(bareudp->sock, sock);
 	return 0;
 }

include/net/udp.h

@@ -467,6 +467,7 @@ void udp_init(void);
 
 DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
 void udp_encap_enable(void);
+void udp_encap_disable(void);
 #if IS_ENABLED(CONFIG_IPV6)
 DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 void udpv6_encap_enable(void);

include/net/udp_tunnel.h

@@ -181,7 +181,6 @@ static inline void udp_tunnel_encap_enable(struct socket *sock)
 #if IS_ENABLED(CONFIG_IPV6)
 	if (sock->sk->sk_family == PF_INET6)
 		ipv6_stub->udpv6_encap_enable();
-	else
 #endif
 	udp_encap_enable();
 }

net/ipv4/udp.c

@@ -596,6 +596,12 @@ void udp_encap_enable(void)
 }
 EXPORT_SYMBOL(udp_encap_enable);
 
+void udp_encap_disable(void)
+{
+	static_branch_dec(&udp_encap_needed_key);
+}
+EXPORT_SYMBOL(udp_encap_disable);
+
 /* Handler for tunnels with arbitrary destination ports: no socket lookup, go
  * through error handlers in encapsulations looking for a match.
  */

net/ipv6/udp.c

@@ -1608,8 +1608,10 @@ void udpv6_destroy_sock(struct sock *sk)
 			if (encap_destroy)
 				encap_destroy(sk);
 		}
-		if (up->encap_enabled)
+		if (up->encap_enabled) {
 			static_branch_dec(&udpv6_encap_needed_key);
+			udp_encap_disable();
+		}
 	}
 
 	inet6_destroy_sock(sk);

net/rxrpc/local_object.c

@@ -16,6 +16,7 @@
 #include <linux/hashtable.h>
 #include <net/sock.h>
 #include <net/udp.h>
+#include <net/udp_tunnel.h>
 #include <net/af_rxrpc.h>
 #include "ar-internal.h"
 
@@ -135,11 +136,7 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
 	udp_sk(usk)->gro_receive = NULL;
 	udp_sk(usk)->gro_complete = NULL;
 
-	udp_encap_enable();
-#if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
-	if (local->srx.transport.family == AF_INET6)
-		udpv6_encap_enable();
-#endif
+	udp_tunnel_encap_enable(local->socket);
 	usk->sk_error_report = rxrpc_error_report;
 
 	/* if a local address was supplied then bind it */