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

static struct class ipvtap_class = {
         .name = "ipvtap",
         .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_device *dev,
                          struct rtnl_newlink_params *params,
                          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(dev, params, 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_DESCRIPTION("IP-VLAN based tap driver");
MODULE_LICENSE("GPL");