udp_tunnel: add config option to bind to a device

Alexis Bauvin · davem330 · commit da5095d05286 · 2018-12-03T14:15:26.000-08:00
UDP tunnel sockets are always opened unbound to a specific device. This
patch allow the socket to be bound on a custom device, which
incidentally makes UDP tunnels VRF-aware if binding to an l3mdev.

Signed-off-by: Alexis Bauvin &lt;abauvin@scaleway.com&gt;
Reviewed-by: Amine Kherbouche &lt;akherbouche@scaleway.com&gt;
Tested-by: Amine Kherbouche &lt;akherbouche@scaleway.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
@@ -30,6 +30,7 @@ struct udp_port_cfg {
 
 	__be16			local_udp_port;
 	__be16			peer_udp_port;
+	int			bind_ifindex;
 	unsigned int		use_udp_checksums:1,
 				use_udp6_tx_checksums:1,
 				use_udp6_rx_checksums:1,
diff --git a/net/ipv4/udp_tunnel.c b/net/ipv4/udp_tunnel.c
@@ -20,6 +20,23 @@ int udp_sock_create4(struct net *net, struct udp_port_cfg *cfg,
 	if (err < 0)
 		goto error;
 
+	if (cfg->bind_ifindex) {
+		struct net_device *dev;
+
+		dev = dev_get_by_index(net, cfg->bind_ifindex);
+		if (!dev) {
+			err = -ENODEV;
+			goto error;
+		}
+
+		err = kernel_setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE,
+					dev->name, strlen(dev->name) + 1);
+		dev_put(dev);
+
+		if (err < 0)
+			goto error;
+	}
+
 	udp_addr.sin_family = AF_INET;
 	udp_addr.sin_addr = cfg->local_ip;
 	udp_addr.sin_port = cfg->local_udp_port;
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
@@ -31,6 +31,22 @@ int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
 		if (err < 0)
 			goto error;
 	}
+	if (cfg->bind_ifindex) {
+		struct net_device *dev;
+
+		dev = dev_get_by_index(net, cfg->bind_ifindex);
+		if (!dev) {
+			err = -ENODEV;
+			goto error;
+		}
+
+		err = kernel_setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE,
+					dev->name, strlen(dev->name) + 1);
+		dev_put(dev);
+
+		if (err < 0)
+			goto error;
+	}
 
 	udp6_addr.sin6_family = AF_INET6;
 	memcpy(&udp6_addr.sin6_addr, &cfg->local_ip6,
