[PATCH net-next v9 02/23] net: introduce OpenVPN Data Channel Offload (ovpn)

@@ -17467,6 +17467,14 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs.git
 F:	Documentation/filesystems/overlayfs.rst
 F:	fs/overlayfs/
 
+OPENVPN DATA CHANNEL OFFLOAD
+M:	Antonio Quartulli <antonio@openvpn.net>
+L:	openvpn-devel@lists.sourceforge.net (moderated for non-subscribers)
+L:	netdev@vger.kernel.org
+S:	Maintained
+T:	git https://github.com/OpenVPN/linux-kernel-ovpn.git
+F:	drivers/net/ovpn/
+
 P54 WIRELESS DRIVER
 M:	Christian Lamparter <chunkeey@googlemail.com>
 L:	linux-wireless@vger.kernel.org

@@ -115,6 +115,20 @@ config WIREGUARD_DEBUG
 
 	  Say N here unless you know what you're doing.
 
+config OVPN
+	tristate "OpenVPN data channel offload"
+	depends on NET && INET
+	select NET_UDP_TUNNEL
+	select DST_CACHE
+	select CRYPTO
+	select CRYPTO_AES
+	select CRYPTO_GCM
+	select CRYPTO_CHACHA20POLY1305
+	select STREAM_PARSER
+	help
+	  This module enhances the performance of the OpenVPN userspace software
+	  by offloading the data channel processing to kernelspace.
+
 config EQUALIZER
 	tristate "EQL (serial line load balancing) support"
 	help

@@ -11,6 +11,7 @@ obj-$(CONFIG_IPVLAN) += ipvlan/
 obj-$(CONFIG_IPVTAP) += ipvlan/
 obj-$(CONFIG_DUMMY) += dummy.o
 obj-$(CONFIG_WIREGUARD) += wireguard/
+obj-$(CONFIG_OVPN) += ovpn/
 obj-$(CONFIG_EQUALIZER) += eql.o
 obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_MACSEC) += macsec.o

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# ovpn -- OpenVPN data channel offload in kernel space
+#
+# Copyright (C) 2020-2024 OpenVPN, Inc.
+#
+# Author:	Antonio Quartulli <antonio@openvpn.net>
+
+obj-$(CONFIG_OVPN) := ovpn.o
+ovpn-y += main.o
+ovpn-y += io.o

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/*  OpenVPN data channel offload
+ *
+ *  Copyright (C) 2019-2024 OpenVPN, Inc.
+ *
+ *  Author:	James Yonan <james@openvpn.net>
+ *		Antonio Quartulli <antonio@openvpn.net>
+ */
+
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+
+#include "io.h"
+
+/* Send user data to the network
+ */
+netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	skb_tx_error(skb);
+	kfree_skb(skb);
+	return NET_XMIT_DROP;
+}

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OpenVPN data channel offload
+ *
+ *  Copyright (C) 2019-2024 OpenVPN, Inc.
+ *
+ *  Author:	James Yonan <james@openvpn.net>
+ *		Antonio Quartulli <antonio@openvpn.net>
+ */
+
+#ifndef _NET_OVPN_OVPN_H_
+#define _NET_OVPN_OVPN_H_
+
+netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev);
+
+#endif /* _NET_OVPN_OVPN_H_ */

@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*  OpenVPN data channel offload
+ *
+ *  Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ *  Author:	Antonio Quartulli <antonio@openvpn.net>
+ *		James Yonan <james@openvpn.net>
+ */
+
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <net/rtnetlink.h>
+
+#include "main.h"
+#include "io.h"
+
+/* Driver info */
+#define DRV_DESCRIPTION	"OpenVPN data channel offload (ovpn)"
+#define DRV_COPYRIGHT	"(C) 2020-2024 OpenVPN, Inc."
+
+/**
+ * ovpn_dev_is_valid - check if the netdevice is of type 'ovpn'
+ * @dev: the interface to check
+ *
+ * Return: whether the netdevice is of type 'ovpn'
+ */
+bool ovpn_dev_is_valid(const struct net_device *dev)
+{
+	return dev->netdev_ops->ndo_start_xmit == ovpn_net_xmit;
+}
+
+static int ovpn_newlink(struct net *src_net, struct net_device *dev,
+			struct nlattr *tb[], struct nlattr *data[],
+			struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct rtnl_link_ops ovpn_link_ops = {
+	.kind = "ovpn",
+	.netns_refund = false,
+	.newlink = ovpn_newlink,
+	.dellink = unregister_netdevice_queue,
+};
+
+static int ovpn_netdev_notifier_call(struct notifier_block *nb,
+				     unsigned long state, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (!ovpn_dev_is_valid(dev))
+		return NOTIFY_DONE;
+
+	switch (state) {
+	case NETDEV_REGISTER:
+		/* add device to internal list for later destruction upon
+		 * unregistration
+		 */
+		break;
+	case NETDEV_UNREGISTER:
+		/* can be delivered multiple times, so check registered flag,
+		 * then destroy the interface
+		 */
+		break;
+	case NETDEV_POST_INIT:
+	case NETDEV_GOING_DOWN:
+	case NETDEV_DOWN:
+	case NETDEV_UP:
+	case NETDEV_PRE_UP:
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block ovpn_netdev_notifier = {
+	.notifier_call = ovpn_netdev_notifier_call,
+};
+
+static int __init ovpn_init(void)
+{
+	int err = register_netdevice_notifier(&ovpn_netdev_notifier);
+
+	if (err) {
+		pr_err("ovpn: can't register netdevice notifier: %d\n", err);
+		return err;
+	}
+
+	err = rtnl_link_register(&ovpn_link_ops);
+	if (err) {
+		pr_err("ovpn: can't register rtnl link ops: %d\n", err);
+		goto unreg_netdev;
+	}
+
+	return 0;
+
+unreg_netdev:
+	unregister_netdevice_notifier(&ovpn_netdev_notifier);
+	return err;
+}
+
+static __exit void ovpn_cleanup(void)
+{
+	rtnl_link_unregister(&ovpn_link_ops);
+	unregister_netdevice_notifier(&ovpn_netdev_notifier);
+
+	rcu_barrier();
+}
+
+module_init(ovpn_init);
+module_exit(ovpn_cleanup);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_AUTHOR(DRV_COPYRIGHT);
+MODULE_LICENSE("GPL");

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*  OpenVPN data channel offload
+ *
+ *  Copyright (C) 2019-2024 OpenVPN, Inc.
+ *
+ *  Author:	James Yonan <james@openvpn.net>
+ *		Antonio Quartulli <antonio@openvpn.net>
+ */
+
+#ifndef _NET_OVPN_MAIN_H_
+#define _NET_OVPN_MAIN_H_
+
+bool ovpn_dev_is_valid(const struct net_device *dev);
+
+#endif /* _NET_OVPN_MAIN_H_ */

@@ -43,5 +43,6 @@ struct udphdr {
 #define UDP_ENCAP_GTP1U		5 /* 3GPP TS 29.060 */
 #define UDP_ENCAP_RXRPC		6
 #define TCP_ENCAP_ESPINTCP	7 /* Yikes, this is really xfrm encap types. */
+#define UDP_ENCAP_OVPNINUDP	8 /* OpenVPN traffic */
 
 #endif /* _UAPI_LINUX_UDP_H */