[PATCHv3 net-next] udp: call udp_encap_enable for v6 sockets when enabling encap

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

v1->v2:
  - add udp_encap_disable() and export it.
v2->v3:
  - add the change for rxrpc and bareudp into one patch, as Alex
    suggested.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 drivers/net/bareudp.c    | 6 ------
 include/net/udp.h        | 1 +
 include/net/udp_tunnel.h | 3 +--
 net/ipv4/udp.c           | 6 ++++++
 net/ipv6/udp.c           | 4 +++-
 net/rxrpc/local_object.c | 4 +++-
 6 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index 1b8f597..7511bca 100644
--- a/drivers/net/bareudp.c
+++ b/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;
 }

diff --git a/include/net/udp.h b/include/net/udp.h
index 877832b..1e7b6cd 100644
--- a/include/net/udp.h
+++ b/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);

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 282d10e..afc7ce7 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h

@@ -181,9 +181,8 @@ 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();
+	udp_encap_enable();
 }
 
 #define UDP_TUNNEL_NIC_MAX_TABLES	4

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 69ea765..48208fb 100644
--- a/net/ipv4/udp.c
+++ b/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.
  */

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b9f3dfd..d754292 100644
--- a/net/ipv6/udp.c
+++ b/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);

diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 8c28810..fc10234 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c

@@ -135,11 +135,13 @@ 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();
+	else
 #endif
+		udp_encap_enable();
+
 	usk->sk_error_report = rxrpc_error_report;
 
 	/* if a local address was supplied then bind it */

-- 
2.1.0

On Tue, Jan 26, 2021 at 10:35 AM Willem de Bruijn
[off-list ref] wrote:

On Sun, Jan 24, 2021 at 3:57 AM Xin Long [off-list ref] wrote:

quoted

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

v1->v2:
  - add udp_encap_disable() and export it.
v2->v3:
  - add the change for rxrpc and bareudp into one patch, as Alex
    suggested.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 drivers/net/bareudp.c    | 6 ------
 include/net/udp.h        | 1 +
 include/net/udp_tunnel.h | 3 +--
 net/ipv4/udp.c           | 6 ++++++
 net/ipv6/udp.c           | 4 +++-
 net/rxrpc/local_object.c | 4 +++-
 6 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index 1b8f597..7511bca 100644
--- a/drivers/net/bareudp.c
+++ b/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;
 }

diff --git a/include/net/udp.h b/include/net/udp.h
index 877832b..1e7b6cd 100644
--- a/include/net/udp.h
+++ b/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);

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 282d10e..afc7ce7 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h

@@ -181,9 +181,8 @@ 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();
+       udp_encap_enable();
 }

 #define UDP_TUNNEL_NIC_MAX_TABLES      4

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 69ea765..48208fb 100644
--- a/net/ipv4/udp.c
+++ b/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.
  */

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b9f3dfd..d754292 100644
--- a/net/ipv6/udp.c
+++ b/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);

diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 8c28810..fc10234 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c

@@ -135,11 +135,13 @@ 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();
+       else
 #endif
+               udp_encap_enable();
+

If ipv6 this socket will decrement both static branches in
udpv6_destroy_sock. Shouldn't it increment both, then? Similar to
udp_tunnel_encap_enable, but open coded.

My mistake, all above should just call udp_tunnel_encap_enable(),
otherwise, it won't be decreased in udpv6_destroy_sock(). will respost.

Thanks.

On Sun, Jan 24, 2021 at 3:57 AM Xin Long [off-list ref] wrote:

If ipv6 this socket will decrement both static branches in
udpv6_destroy_sock. Shouldn't it increment both, then? Similar to
udp_tunnel_encap_enable, but open coded.