// SPDX-License-Identifier: GPL-2.0-only
#include <linux/etherdevice.h>
#include <linux/if_macvlan.h>
#include <linux/if_tap.h>
#include <linux/if_vlan.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/signal.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>
#include <linux/skb_array.h>

struct macvtap_dev {
        struct macvlan_dev vlan;
        struct tap_dev    tap;
};

/*
 * Variables for dealing with macvtaps device numbers.
 */
static dev_t macvtap_major;

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

static struct class macvtap_class = {
        .name = "macvtap",
        .owner = THIS_MODULE,
        .ns_type = &net_ns_type_operations,
        .namespace = macvtap_net_namespace,
};
static struct cdev macvtap_cdev;

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

static void macvtap_count_tx_dropped(struct tap_dev *tap)
{
        struct macvtap_dev *vlantap = container_of(tap, struct macvtap_dev, tap);
        struct macvlan_dev *vlan = &vlantap->vlan;

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

static void macvtap_count_rx_dropped(struct tap_dev *tap)
{
        struct macvtap_dev *vlantap = container_of(tap, struct macvtap_dev, tap);
        struct macvlan_dev *vlan = &vlantap->vlan;

        macvlan_count_rx(vlan, 0, 0, 0);
}

static void macvtap_update_features(struct tap_dev *tap,
                                    netdev_features_t features)
{
        struct macvtap_dev *vlantap = container_of(tap, struct macvtap_dev, tap);
        struct macvlan_dev *vlan = &vlantap->vlan;

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

static int macvtap_newlink(struct net *src_net, struct net_device *dev,
                           struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
{
        struct macvtap_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;

        /* Register callbacks for rx/tx drops accounting and updating
         * net_device features
         */
        vlantap->tap.count_tx_dropped = macvtap_count_tx_dropped;
        vlantap->tap.count_rx_dropped = macvtap_count_rx_dropped;
        vlantap->tap.update_features  = macvtap_update_features;

        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 = macvlan_common_newlink(src_net, dev, tb, data, extack);
        if (err) {
                netdev_rx_handler_unregister(dev);
                return err;
        }

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

        return 0;
}

static void macvtap_dellink(struct net_device *dev,
                            struct list_head *head)
{
        struct macvtap_dev *vlantap = netdev_priv(dev);

        netdev_rx_handler_unregister(dev);
        tap_del_queues(&vlantap->tap);
        macvlan_dellink(dev, head);
}

static void macvtap_setup(struct net_device *dev)
{
        macvlan_common_setup(dev);
        dev->tx_queue_len = TUN_READQ_SIZE;
}

static struct net *macvtap_link_net(const struct net_device *dev)
{
        return dev_net(macvlan_dev_real_dev(dev));
}

static struct rtnl_link_ops macvtap_link_ops __read_mostly = {
        .kind           = "macvtap",
        .setup          = macvtap_setup,
        .newlink        = macvtap_newlink,
        .dellink        = macvtap_dellink,
        .get_link_net   = macvtap_link_net,
        .priv_size      = sizeof(struct macvtap_dev),
};

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

        if (dev->rtnl_link_ops != &macvtap_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(macvtap_major, &vlantap->tap);
                if (err)
                        return notifier_from_errno(err);

                devt = MKDEV(MAJOR(macvtap_major), vlantap->tap.minor);
                classdev = device_create(&macvtap_class, &dev->dev, devt,
                                         dev, "%s", tap_name);
                if (IS_ERR(classdev)) {
                        tap_free_minor(macvtap_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(macvtap_major), vlantap->tap.minor);
                device_destroy(&macvtap_class, devt);
                tap_free_minor(macvtap_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 macvtap_notifier_block __read_mostly = {
        .notifier_call  = macvtap_device_event,
};

static int macvtap_init(void)
{
        int err;

        err = tap_create_cdev(&macvtap_cdev, &macvtap_major, "macvtap",
                              THIS_MODULE);
        if (err)
                goto out1;

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

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

        err = macvlan_link_register(&macvtap_link_ops);
        if (err)
                goto out4;

        return 0;

out4:
        unregister_netdevice_notifier(&macvtap_notifier_block);
out3:
        class_unregister(&macvtap_class);
out2:
        tap_destroy_cdev(macvtap_major, &macvtap_cdev);
out1:
        return err;
}
module_init(macvtap_init);

static void macvtap_exit(void)
{
        rtnl_link_unregister(&macvtap_link_ops);
        unregister_netdevice_notifier(&macvtap_notifier_block);
        class_unregister(&macvtap_class);
        tap_destroy_cdev(macvtap_major, &macvtap_cdev);
}
module_exit(macvtap_exit);

MODULE_ALIAS_RTNL_LINK("macvtap");
MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
MODULE_LICENSE("GPL");