// SPDX-License-Identifier: GPL-2.0-only
#include <linux/etherdevice.h>
#include "ipvlan.h"
#include <linux/if_vlan.h>
#include <linux/if_tap.h>
#include <linux/interrupt.h>
#include <linux/nsproxy.h>
#include <linux/compat.h>
#include <linux/if_tun.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/cdev.h>
#include <linux/idr.h>
#include <linux/fs.h>
#include <linux/uio.h>

#include <net/net_namespace.h>
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <linux/virtio_net.h>

#define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \
		      NETIF_F_TSO6)

static dev_t ipvtap_major;
static struct cdev ipvtap_cdev;

static const void *ipvtap_net_namespace(struct device *d)
{
	struct net_device *dev = to_net_dev(d->parent);
	return dev_net(dev);
}

static struct class ipvtap_class = {
	 .name = "ipvtap",
	 .owner = THIS_MODULE,
	 .ns_type = &net_ns_type_operations,
	 .namespace = ipvtap_net_namespace,
};

struct ipvtap_dev {
	struct ipvl_dev vlan;
	struct tap_dev	  tap;
};

static void ipvtap_count_tx_dropped(struct tap_dev *tap)
{
	struct ipvtap_dev *vlantap = container_of(tap, struct ipvtap_dev, tap);
	struct ipvl_dev *vlan = &vlantap->vlan;

	this_cpu_inc(vlan->pcpu_stats->tx_drps);
}

static void ipvtap_count_rx_dropped(struct tap_dev *tap)
{
	struct ipvtap_dev *vlantap = container_of(tap, struct ipvtap_dev, tap);
	struct ipvl_dev *vlan = &vlantap->vlan;

	ipvlan_count_rx(vlan, 0, 0, 0);
}

static void ipvtap_update_features(struct tap_dev *tap,
				   netdev_features_t features)
{
	struct ipvtap_dev *vlantap = container_of(tap, struct ipvtap_dev, tap);
	struct ipvl_dev *vlan = &vlantap->vlan;

	vlan->sfeatures = features;
	netdev_update_features(vlan->dev);
}

static int ipvtap_newlink(struct net *src_net, struct net_device *dev,
			  struct nlattr *tb[], struct nlattr *data[],
			  struct netlink_ext_ack *extack)
{
	struct ipvtap_dev *vlantap = netdev_priv(dev);
	int err;

	INIT_LIST_HEAD(&vlantap->tap.queue_list);

	/* Since macvlan supports all offloads by default, make
	 * tap support all offloads also.
	 */
	vlantap->tap.tap_features = TUN_OFFLOADS;
	vlantap->tap.count_tx_dropped = ipvtap_count_tx_dropped;
	vlantap->tap.update_features =	ipvtap_update_features;
	vlantap->tap.count_rx_dropped = ipvtap_count_rx_dropped;

	err = netdev_rx_handler_register(dev, tap_handle_frame, &vlantap->tap);
	if (err)
		return err;

	/* Don't put anything that may fail after macvlan_common_newlink
	 * because we can't undo what it does.
	 */
	err =  ipvlan_link_new(src_net, dev, tb, data, extack);
	if (err) {
		netdev_rx_handler_unregister(dev);
		return err;
	}

	vlantap->tap.dev = vlantap->vlan.dev;

	return err;
}

static void ipvtap_dellink(struct net_device *dev,
			   struct list_head *head)
{
	struct ipvtap_dev *vlan = netdev_priv(dev);

	netdev_rx_handler_unregister(dev);
	tap_del_queues(&vlan->tap);
	ipvlan_link_delete(dev, head);
}

static void ipvtap_setup(struct net_device *dev)
{
	ipvlan_link_setup(dev);
	dev->tx_queue_len = TUN_READQ_SIZE;
	dev->priv_flags &= ~IFF_NO_QUEUE;
}

static struct rtnl_link_ops ipvtap_link_ops __read_mostly = {
	.kind		= "ipvtap",
	.setup		= ipvtap_setup,
	.newlink	= ipvtap_newlink,
	.dellink	= ipvtap_dellink,
	.priv_size	= sizeof(struct ipvtap_dev),
};

static int ipvtap_device_event(struct notifier_block *unused,
			       unsigned long event, void *ptr)
{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	struct ipvtap_dev *vlantap;
	struct device *classdev;
	dev_t devt;
	int err;
	char tap_name[IFNAMSIZ];

	if (dev->rtnl_link_ops != &ipvtap_link_ops)
		return NOTIFY_DONE;

	snprintf(tap_name, IFNAMSIZ, "tap%d", dev->ifindex);
	vlantap = netdev_priv(dev);

	switch (event) {
	case NETDEV_REGISTER:
		/* Create the device node here after the network device has
		 * been registered but before register_netdevice has
		 * finished running.
		 */
		err = tap_get_minor(ipvtap_major, &vlantap->tap);
		if (err)
			return notifier_from_errno(err);

		devt = MKDEV(MAJOR(ipvtap_major), vlantap->tap.minor);
		classdev = device_create(&ipvtap_class, &dev->dev, devt,
					 dev, "%s", tap_name);
		if (IS_ERR(classdev)) {
			tap_free_minor(ipvtap_major, &vlantap->tap);
			return notifier_from_errno(PTR_ERR(classdev));
		}
		err = sysfs_create_link(&dev->dev.kobj, &classdev->kobj,
					tap_name);
		if (err)
			return notifier_from_errno(err);
		break;
	case NETDEV_UNREGISTER:
		/* vlan->minor == 0 if NETDEV_REGISTER above failed */
		if (vlantap->tap.minor == 0)
			break;
		sysfs_remove_link(&dev->dev.kobj, tap_name);
		devt = MKDEV(MAJOR(ipvtap_major), vlantap->tap.minor);
		device_destroy(&ipvtap_class, devt);
		tap_free_minor(ipvtap_major, &vlantap->tap);
		break;
	case NETDEV_CHANGE_TX_QUEUE_LEN:
		if (tap_queue_resize(&vlantap->tap))
			return NOTIFY_BAD;
		break;
	}

	return NOTIFY_DONE;
}

static struct notifier_block ipvtap_notifier_block __read_mostly = {
	.notifier_call	= ipvtap_device_event,
};

static int __init ipvtap_init(void)
{
	int err;

	err = tap_create_cdev(&ipvtap_cdev, &ipvtap_major, "ipvtap",
			      THIS_MODULE);
	if (err)
		goto out1;

	err = class_register(&ipvtap_class);
	if (err)
		goto out2;

	err = register_netdevice_notifier(&ipvtap_notifier_block);
	if (err)
		goto out3;

	err = ipvlan_link_register(&ipvtap_link_ops);
	if (err)
		goto out4;

	return 0;

out4:
	unregister_netdevice_notifier(&ipvtap_notifier_block);
out3:
	class_unregister(&ipvtap_class);
out2:
	tap_destroy_cdev(ipvtap_major, &ipvtap_cdev);
out1:
	return err;
}
module_init(ipvtap_init);

static void __exit ipvtap_exit(void)
{
	rtnl_link_unregister(&ipvtap_link_ops);
	unregister_netdevice_notifier(&ipvtap_notifier_block);
	class_unregister(&ipvtap_class);
	tap_destroy_cdev(ipvtap_major, &ipvtap_cdev);
}
module_exit(ipvtap_exit);
MODULE_ALIAS_RTNL_LINK("ipvtap");
MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
MODULE_LICENSE("GPL");