// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2007-2020  B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich
 */

#include "soft-interface.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/cache.h>
#include <linux/compiler.h>
#include <linux/cpumask.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/gfp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/percpu.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/types.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>

#include "bat_algo.h"
#include "bridge_loop_avoidance.h"
#include "debugfs.h"
#include "distributed-arp-table.h"
#include "gateway_client.h"
#include "hard-interface.h"
#include "multicast.h"
#include "network-coding.h"
#include "originator.h"
#include "send.h"
#include "sysfs.h"
#include "translation-table.h"

/**
 * batadv_skb_head_push() - Increase header size and move (push) head pointer
 * @skb: packet buffer which should be modified
 * @len: number of bytes to add
 *
 * Return: 0 on success or negative error number in case of failure
 */
int batadv_skb_head_push(struct sk_buff *skb, unsigned int len)
{
        int result;

        /* TODO: We must check if we can release all references to non-payload
         * data using __skb_header_release in our skbs to allow skb_cow_header
         * to work optimally. This means that those skbs are not allowed to read
         * or write any data which is before the current position of skb->data
         * after that call and thus allow other skbs with the same data buffer
         * to write freely in that area.
         */
        result = skb_cow_head(skb, len);
        if (result < 0)
                return result;

        skb_push(skb, len);
        return 0;
}

static int batadv_interface_open(struct net_device *dev)
{
        netif_start_queue(dev);
        return 0;
}

static int batadv_interface_release(struct net_device *dev)
{
        netif_stop_queue(dev);
        return 0;
}

/**
 * batadv_sum_counter() - Sum the cpu-local counters for index 'idx'
 * @bat_priv: the bat priv with all the soft interface information
 * @idx: index of counter to sum up
 *
 * Return: sum of all cpu-local counters
 */
static u64 batadv_sum_counter(struct batadv_priv *bat_priv,  size_t idx)
{
        u64 *counters, sum = 0;
        int cpu;

        for_each_possible_cpu(cpu) {
                counters = per_cpu_ptr(bat_priv->bat_counters, cpu);
                sum += counters[idx];
        }

        return sum;
}

static struct net_device_stats *batadv_interface_stats(struct net_device *dev)
{
        struct batadv_priv *bat_priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;

        stats->tx_packets = batadv_sum_counter(bat_priv, BATADV_CNT_TX);
        stats->tx_bytes = batadv_sum_counter(bat_priv, BATADV_CNT_TX_BYTES);
        stats->tx_dropped = batadv_sum_counter(bat_priv, BATADV_CNT_TX_DROPPED);
        stats->rx_packets = batadv_sum_counter(bat_priv, BATADV_CNT_RX);
        stats->rx_bytes = batadv_sum_counter(bat_priv, BATADV_CNT_RX_BYTES);
        return stats;
}

static int batadv_interface_set_mac_addr(struct net_device *dev, void *p)
{
        struct batadv_priv *bat_priv = netdev_priv(dev);
        struct batadv_softif_vlan *vlan;
        struct sockaddr *addr = p;
        u8 old_addr[ETH_ALEN];

        if (!is_valid_ether_addr(addr->sa_data))
                return -EADDRNOTAVAIL;

        ether_addr_copy(old_addr, dev->dev_addr);
        ether_addr_copy(dev->dev_addr, addr->sa_data);

        /* only modify transtable if it has been initialized before */
        if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
                return 0;

        rcu_read_lock();
        hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) {
                batadv_tt_local_remove(bat_priv, old_addr, vlan->vid,
                                       "mac address changed", false);
                batadv_tt_local_add(dev, addr->sa_data, vlan->vid,
                                    BATADV_NULL_IFINDEX, BATADV_NO_MARK);
        }
        rcu_read_unlock();

        return 0;
}

static int batadv_interface_change_mtu(struct net_device *dev, int new_mtu)
{
        /* check ranges */
        if (new_mtu < 68 || new_mtu > batadv_hardif_min_mtu(dev))
                return -EINVAL;

        dev->mtu = new_mtu;

        return 0;
}

/**
 * batadv_interface_set_rx_mode() - set the rx mode of a device
 * @dev: registered network device to modify
 *
 * We do not actually need to set any rx filters for the virtual batman
 * soft interface. However a dummy handler enables a user to set static
 * multicast listeners for instance.
 */
static void batadv_interface_set_rx_mode(struct net_device *dev)
{
}

static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
                                       struct net_device *soft_iface)
{
        struct ethhdr *ethhdr;
        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        struct batadv_hard_iface *primary_if = NULL;
        struct batadv_bcast_packet *bcast_packet;
        static const u8 stp_addr[ETH_ALEN] = {0x01, 0x80, 0xC2, 0x00,
                                              0x00, 0x00};
        static const u8 ectp_addr[ETH_ALEN] = {0xCF, 0x00, 0x00, 0x00,
                                               0x00, 0x00};
        enum batadv_dhcp_recipient dhcp_rcp = BATADV_DHCP_NO;
        u8 *dst_hint = NULL, chaddr[ETH_ALEN];
        struct vlan_ethhdr *vhdr;
        unsigned int header_len = 0;
        int data_len = skb->len, ret;
        unsigned long brd_delay = 1;
        bool do_bcast = false, client_added;
        unsigned short vid;
        u32 seqno;
        int gw_mode;
        enum batadv_forw_mode forw_mode = BATADV_FORW_SINGLE;
        struct batadv_orig_node *mcast_single_orig = NULL;
        int network_offset = ETH_HLEN;
        __be16 proto;

        if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
                goto dropped;

        /* reset control block to avoid left overs from previous users */
        memset(skb->cb, 0, sizeof(struct batadv_skb_cb));

        netif_trans_update(soft_iface);
        vid = batadv_get_vid(skb, 0);

        skb_reset_mac_header(skb);
        ethhdr = eth_hdr(skb);

        proto = ethhdr->h_proto;

        switch (ntohs(proto)) {
        case ETH_P_8021Q:
                if (!pskb_may_pull(skb, sizeof(*vhdr)))
                        goto dropped;
                vhdr = vlan_eth_hdr(skb);
                proto = vhdr->h_vlan_encapsulated_proto;

                /* drop batman-in-batman packets to prevent loops */
                if (proto != htons(ETH_P_BATMAN)) {
                        network_offset += VLAN_HLEN;
                        break;
                }

                fallthrough;
        case ETH_P_BATMAN:
                goto dropped;
        }

        skb_set_network_header(skb, network_offset);

        if (batadv_bla_tx(bat_priv, skb, vid))
                goto dropped;

        /* skb->data might have been reallocated by batadv_bla_tx() */
        ethhdr = eth_hdr(skb);

        /* Register the client MAC in the transtable */
        if (!is_multicast_ether_addr(ethhdr->h_source) &&
            !batadv_bla_is_loopdetect_mac(ethhdr->h_source)) {
                client_added = batadv_tt_local_add(soft_iface, ethhdr->h_source,
                                                   vid, skb->skb_iif,
                                                   skb->mark);
                if (!client_added)
                        goto dropped;
        }

        /* Snoop address candidates from DHCPACKs for early DAT filling */
        batadv_dat_snoop_outgoing_dhcp_ack(bat_priv, skb, proto, vid);

        /* don't accept stp packets. STP does not help in meshes.
         * better use the bridge loop avoidance ...
         *
         * The same goes for ECTP sent at least by some Cisco Switches,
         * it might confuse the mesh when used with bridge loop avoidance.
         */
        if (batadv_compare_eth(ethhdr->h_dest, stp_addr))
                goto dropped;

        if (batadv_compare_eth(ethhdr->h_dest, ectp_addr))
                goto dropped;

        gw_mode = atomic_read(&bat_priv->gw.mode);
        if (is_multicast_ether_addr(ethhdr->h_dest)) {
                /* if gw mode is off, broadcast every packet */
                if (gw_mode == BATADV_GW_MODE_OFF) {
                        do_bcast = true;
                        goto send;
                }

                dhcp_rcp = batadv_gw_dhcp_recipient_get(skb, &header_len,
                                                        chaddr);
                /* skb->data may have been modified by
                 * batadv_gw_dhcp_recipient_get()
                 */
                ethhdr = eth_hdr(skb);
                /* if gw_mode is on, broadcast any non-DHCP message.
                 * All the DHCP packets are going to be sent as unicast
                 */
                if (dhcp_rcp == BATADV_DHCP_NO) {
                        do_bcast = true;
                        goto send;
                }

                if (dhcp_rcp == BATADV_DHCP_TO_CLIENT)
                        dst_hint = chaddr;
                else if ((gw_mode == BATADV_GW_MODE_SERVER) &&
                         (dhcp_rcp == BATADV_DHCP_TO_SERVER))
                        /* gateways should not forward any DHCP message if
                         * directed to a DHCP server
                         */
                        goto dropped;

send:
                if (do_bcast && !is_broadcast_ether_addr(ethhdr->h_dest)) {
                        forw_mode = batadv_mcast_forw_mode(bat_priv, skb,
                                                           &mcast_single_orig);
                        if (forw_mode == BATADV_FORW_NONE)
                                goto dropped;

                        if (forw_mode == BATADV_FORW_SINGLE ||
                            forw_mode == BATADV_FORW_SOME)
                                do_bcast = false;
                }
        }

        batadv_skb_set_priority(skb, 0);

        /* ethernet packet should be broadcasted */
        if (do_bcast) {
                primary_if = batadv_primary_if_get_selected(bat_priv);
                if (!primary_if)
                        goto dropped;

                /* in case of ARP request, we do not immediately broadcasti the
                 * packet, instead we first wait for DAT to try to retrieve the
                 * correct ARP entry
                 */
                if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
                        brd_delay = msecs_to_jiffies(ARP_REQ_DELAY);

                if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0)
                        goto dropped;

                bcast_packet = (struct batadv_bcast_packet *)skb->data;
                bcast_packet->version = BATADV_COMPAT_VERSION;
                bcast_packet->ttl = BATADV_TTL;

                /* batman packet type: broadcast */
                bcast_packet->packet_type = BATADV_BCAST;
                bcast_packet->reserved = 0;

                /* hw address of first interface is the orig mac because only
                 * this mac is known throughout the mesh
                 */
                ether_addr_copy(bcast_packet->orig,
                                primary_if->net_dev->dev_addr);

                /* set broadcast sequence number */
                seqno = atomic_inc_return(&bat_priv->bcast_seqno);
                bcast_packet->seqno = htonl(seqno);

                batadv_add_bcast_packet_to_list(bat_priv, skb, brd_delay, true);

                /* a copy is stored in the bcast list, therefore removing
                 * the original skb.
                 */
                consume_skb(skb);

        /* unicast packet */
        } else {
                /* DHCP packets going to a server will use the GW feature */
                if (dhcp_rcp == BATADV_DHCP_TO_SERVER) {
                        ret = batadv_gw_out_of_range(bat_priv, skb);
                        if (ret)
                                goto dropped;
                        ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
                } else if (mcast_single_orig) {
                        ret = batadv_send_skb_unicast(bat_priv, skb,
                                                      BATADV_UNICAST, 0,
                                                      mcast_single_orig, vid);
                } else if (forw_mode == BATADV_FORW_SOME) {
                        ret = batadv_mcast_forw_send(bat_priv, skb, vid);
                } else {
                        if (batadv_dat_snoop_outgoing_arp_request(bat_priv,
                                                                  skb))
                                goto dropped;

                        batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);

                        ret = batadv_send_skb_via_tt(bat_priv, skb, dst_hint,
                                                     vid);
                }
                if (ret != NET_XMIT_SUCCESS)
                        goto dropped_freed;
        }

        batadv_inc_counter(bat_priv, BATADV_CNT_TX);
        batadv_add_counter(bat_priv, BATADV_CNT_TX_BYTES, data_len);
        goto end;

dropped:
        kfree_skb(skb);
dropped_freed:
        batadv_inc_counter(bat_priv, BATADV_CNT_TX_DROPPED);
end:
        if (mcast_single_orig)
                batadv_orig_node_put(mcast_single_orig);
        if (primary_if)
                batadv_hardif_put(primary_if);
        return NETDEV_TX_OK;
}

/**
 * batadv_interface_rx() - receive ethernet frame on local batman-adv interface
 * @soft_iface: local interface which will receive the ethernet frame
 * @skb: ethernet frame for @soft_iface
 * @hdr_size: size of already parsed batman-adv header
 * @orig_node: originator from which the batman-adv packet was sent
 *
 * Sends a ethernet frame to the receive path of the local @soft_iface.
 * skb->data has still point to the batman-adv header with the size @hdr_size.
 * The caller has to have parsed this header already and made sure that at least
 * @hdr_size bytes are still available for pull in @skb.
 *
 * The packet may still get dropped. This can happen when the encapsulated
 * ethernet frame is invalid or contains again an batman-adv packet. Also
 * unicast packets will be dropped directly when it was sent between two
 * isolated clients.
 */
void batadv_interface_rx(struct net_device *soft_iface,
                         struct sk_buff *skb, int hdr_size,
                         struct batadv_orig_node *orig_node)
{
        struct batadv_bcast_packet *batadv_bcast_packet;
        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        struct vlan_ethhdr *vhdr;
        struct ethhdr *ethhdr;
        unsigned short vid;
        bool is_bcast;

        batadv_bcast_packet = (struct batadv_bcast_packet *)skb->data;
        is_bcast = (batadv_bcast_packet->packet_type == BATADV_BCAST);

        skb_pull_rcsum(skb, hdr_size);
        skb_reset_mac_header(skb);

        /* clean the netfilter state now that the batman-adv header has been
         * removed
         */
        nf_reset_ct(skb);

        if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
                goto dropped;

        vid = batadv_get_vid(skb, 0);
        ethhdr = eth_hdr(skb);

        switch (ntohs(ethhdr->h_proto)) {
        case ETH_P_8021Q:
                if (!pskb_may_pull(skb, VLAN_ETH_HLEN))
                        goto dropped;

                vhdr = (struct vlan_ethhdr *)skb->data;

                /* drop batman-in-batman packets to prevent loops */
                if (vhdr->h_vlan_encapsulated_proto != htons(ETH_P_BATMAN))
                        break;

                fallthrough;
        case ETH_P_BATMAN:
                goto dropped;
        }

        /* skb->dev & skb->pkt_type are set here */
        skb->protocol = eth_type_trans(skb, soft_iface);
        skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);

        batadv_inc_counter(bat_priv, BATADV_CNT_RX);
        batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
                           skb->len + ETH_HLEN);

        /* Let the bridge loop avoidance check the packet. If will
         * not handle it, we can safely push it up.
         */
        if (batadv_bla_rx(bat_priv, skb, vid, is_bcast))
                goto out;

        if (orig_node)
                batadv_tt_add_temporary_global_entry(bat_priv, orig_node,
                                                     ethhdr->h_source, vid);

        if (is_multicast_ether_addr(ethhdr->h_dest)) {
                /* set the mark on broadcast packets if AP isolation is ON and
                 * the packet is coming from an "isolated" client
                 */
                if (batadv_vlan_ap_isola_get(bat_priv, vid) &&
                    batadv_tt_global_is_isolated(bat_priv, ethhdr->h_source,
                                                 vid)) {
                        /* save bits in skb->mark not covered by the mask and
                         * apply the mark on the rest
                         */
                        skb->mark &= ~bat_priv->isolation_mark_mask;
                        skb->mark |= bat_priv->isolation_mark;
                }
        } else if (batadv_is_ap_isolated(bat_priv, ethhdr->h_source,
                                         ethhdr->h_dest, vid)) {
                goto dropped;
        }

        netif_rx(skb);
        goto out;

dropped:
        kfree_skb(skb);
out:
        return;
}

/**
 * batadv_softif_vlan_release() - release vlan from lists and queue for free
 *  after rcu grace period
 * @ref: kref pointer of the vlan object
 */
static void batadv_softif_vlan_release(struct kref *ref)
{
        struct batadv_softif_vlan *vlan;

        vlan = container_of(ref, struct batadv_softif_vlan, refcount);

        spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
        hlist_del_rcu(&vlan->list);
        spin_unlock_bh(&vlan->bat_priv->softif_vlan_list_lock);

        kfree_rcu(vlan, rcu);
}

/**
 * batadv_softif_vlan_put() - decrease the vlan object refcounter and
 *  possibly release it
 * @vlan: the vlan object to release
 */
void batadv_softif_vlan_put(struct batadv_softif_vlan *vlan)
{
        if (!vlan)
                return;

        kref_put(&vlan->refcount, batadv_softif_vlan_release);
}

/**
 * batadv_softif_vlan_get() - get the vlan object for a specific vid
 * @bat_priv: the bat priv with all the soft interface information
 * @vid: the identifier of the vlan object to retrieve
 *
 * Return: the private data of the vlan matching the vid passed as argument or
 * NULL otherwise. The refcounter of the returned object is incremented by 1.
 */
struct batadv_softif_vlan *batadv_softif_vlan_get(struct batadv_priv *bat_priv,
                                                  unsigned short vid)
{
        struct batadv_softif_vlan *vlan_tmp, *vlan = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(vlan_tmp, &bat_priv->softif_vlan_list, list) {
                if (vlan_tmp->vid != vid)
                        continue;

                if (!kref_get_unless_zero(&vlan_tmp->refcount))
                        continue;

                vlan = vlan_tmp;
                break;
        }
        rcu_read_unlock();

        return vlan;
}

/**
 * batadv_softif_create_vlan() - allocate the needed resources for a new vlan
 * @bat_priv: the bat priv with all the soft interface information
 * @vid: the VLAN identifier
 *
 * Return: 0 on success, a negative error otherwise.
 */
int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
{
        struct batadv_softif_vlan *vlan;
        int err;

        spin_lock_bh(&bat_priv->softif_vlan_list_lock);

        vlan = batadv_softif_vlan_get(bat_priv, vid);
        if (vlan) {
                batadv_softif_vlan_put(vlan);
                spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
                return -EEXIST;
        }

        vlan = kzalloc(sizeof(*vlan), GFP_ATOMIC);
        if (!vlan) {
                spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
                return -ENOMEM;
        }

        vlan->bat_priv = bat_priv;
        vlan->vid = vid;
        kref_init(&vlan->refcount);

        atomic_set(&vlan->ap_isolation, 0);

        kref_get(&vlan->refcount);
        hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
        spin_unlock_bh(&bat_priv->softif_vlan_list_lock);

        /* batadv_sysfs_add_vlan cannot be in the spinlock section due to the
         * sleeping behavior of the sysfs functions and the fs_reclaim lock
         */
        err = batadv_sysfs_add_vlan(bat_priv->soft_iface, vlan);
        if (err) {
                /* ref for the function */
                batadv_softif_vlan_put(vlan);

                /* ref for the list */
                batadv_softif_vlan_put(vlan);
                return err;
        }

        /* add a new TT local entry. This one will be marked with the NOPURGE
         * flag
         */
        batadv_tt_local_add(bat_priv->soft_iface,
                            bat_priv->soft_iface->dev_addr, vid,
                            BATADV_NULL_IFINDEX, BATADV_NO_MARK);

        /* don't return reference to new softif_vlan */
        batadv_softif_vlan_put(vlan);

        return 0;
}

/**
 * batadv_softif_destroy_vlan() - remove and destroy a softif_vlan object
 * @bat_priv: the bat priv with all the soft interface information
 * @vlan: the object to remove
 */
static void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
                                       struct batadv_softif_vlan *vlan)
{
        /* explicitly remove the associated TT local entry because it is marked
         * with the NOPURGE flag
         */
        batadv_tt_local_remove(bat_priv, bat_priv->soft_iface->dev_addr,
                               vlan->vid, "vlan interface destroyed", false);

        batadv_sysfs_del_vlan(bat_priv, vlan);
        batadv_softif_vlan_put(vlan);
}

/**
 * batadv_interface_add_vid() - ndo_add_vid API implementation
 * @dev: the netdev of the mesh interface
 * @proto: protocol of the the vlan id
 * @vid: identifier of the new vlan
 *
 * Set up all the internal structures for handling the new vlan on top of the
 * mesh interface
 *
 * Return: 0 on success or a negative error code in case of failure.
 */
static int batadv_interface_add_vid(struct net_device *dev, __be16 proto,
                                    unsigned short vid)
{
        struct batadv_priv *bat_priv = netdev_priv(dev);
        struct batadv_softif_vlan *vlan;
        int ret;

        /* only 802.1Q vlans are supported.
         * batman-adv does not know how to handle other types
         */
        if (proto != htons(ETH_P_8021Q))
                return -EINVAL;

        vid |= BATADV_VLAN_HAS_TAG;

        /* if a new vlan is getting created and it already exists, it means that
         * it was not deleted yet. batadv_softif_vlan_get() increases the
         * refcount in order to revive the object.
         *
         * if it does not exist then create it.
         */
        vlan = batadv_softif_vlan_get(bat_priv, vid);
        if (!vlan)
                return batadv_softif_create_vlan(bat_priv, vid);

        /* recreate the sysfs object if it was already destroyed (and it should
         * be since we received a kill_vid() for this vlan
         */
        if (!vlan->kobj) {
                ret = batadv_sysfs_add_vlan(bat_priv->soft_iface, vlan);
                if (ret) {
                        batadv_softif_vlan_put(vlan);
                        return ret;
                }
        }

        /* add a new TT local entry. This one will be marked with the NOPURGE
         * flag. This must be added again, even if the vlan object already
         * exists, because the entry was deleted by kill_vid()
         */
        batadv_tt_local_add(bat_priv->soft_iface,
                            bat_priv->soft_iface->dev_addr, vid,
                            BATADV_NULL_IFINDEX, BATADV_NO_MARK);

        return 0;
}

/**
 * batadv_interface_kill_vid() - ndo_kill_vid API implementation
 * @dev: the netdev of the mesh interface
 * @proto: protocol of the the vlan id
 * @vid: identifier of the deleted vlan
 *
 * Destroy all the internal structures used to handle the vlan identified by vid
 * on top of the mesh interface
 *
 * Return: 0 on success, -EINVAL if the specified prototype is not ETH_P_8021Q
 * or -ENOENT if the specified vlan id wasn't registered.
 */
static int batadv_interface_kill_vid(struct net_device *dev, __be16 proto,
                                     unsigned short vid)
{
        struct batadv_priv *bat_priv = netdev_priv(dev);
        struct batadv_softif_vlan *vlan;

        /* only 802.1Q vlans are supported. batman-adv does not know how to
         * handle other types
         */
        if (proto != htons(ETH_P_8021Q))
                return -EINVAL;

        vlan = batadv_softif_vlan_get(bat_priv, vid | BATADV_VLAN_HAS_TAG);
        if (!vlan)
                return -ENOENT;

        batadv_softif_destroy_vlan(bat_priv, vlan);

        /* finally free the vlan object */
        batadv_softif_vlan_put(vlan);

        return 0;
}

/**
 * batadv_softif_init_late() - late stage initialization of soft interface
 * @dev: registered network device to modify
 *
 * Return: error code on failures
 */
static int batadv_softif_init_late(struct net_device *dev)
{
        struct batadv_priv *bat_priv;
        u32 random_seqno;
        int ret;
        size_t cnt_len = sizeof(u64) * BATADV_CNT_NUM;

        bat_priv = netdev_priv(dev);
        bat_priv->soft_iface = dev;

        /* batadv_interface_stats() needs to be available as soon as
         * register_netdevice() has been called
         */
        bat_priv->bat_counters = __alloc_percpu(cnt_len, __alignof__(u64));
        if (!bat_priv->bat_counters)
                return -ENOMEM;

        atomic_set(&bat_priv->aggregated_ogms, 1);
        atomic_set(&bat_priv->bonding, 0);
#ifdef CONFIG_BATMAN_ADV_BLA
        atomic_set(&bat_priv->bridge_loop_avoidance, 1);
#endif
#ifdef CONFIG_BATMAN_ADV_DAT
        atomic_set(&bat_priv->distributed_arp_table, 1);
#endif
#ifdef CONFIG_BATMAN_ADV_MCAST
        atomic_set(&bat_priv->multicast_mode, 1);
        atomic_set(&bat_priv->multicast_fanout, 16);
        atomic_set(&bat_priv->mcast.num_want_all_unsnoopables, 0);
        atomic_set(&bat_priv->mcast.num_want_all_ipv4, 0);
        atomic_set(&bat_priv->mcast.num_want_all_ipv6, 0);
#endif
        atomic_set(&bat_priv->gw.mode, BATADV_GW_MODE_OFF);
        atomic_set(&bat_priv->gw.bandwidth_down, 100);
        atomic_set(&bat_priv->gw.bandwidth_up, 20);
        atomic_set(&bat_priv->orig_interval, 1000);
        atomic_set(&bat_priv->hop_penalty, 30);
#ifdef CONFIG_BATMAN_ADV_DEBUG
        atomic_set(&bat_priv->log_level, 0);
#endif
        atomic_set(&bat_priv->fragmentation, 1);
        atomic_set(&bat_priv->packet_size_max, ETH_DATA_LEN);
        atomic_set(&bat_priv->bcast_queue_left, BATADV_BCAST_QUEUE_LEN);
        atomic_set(&bat_priv->batman_queue_left, BATADV_BATMAN_QUEUE_LEN);

        atomic_set(&bat_priv->mesh_state, BATADV_MESH_INACTIVE);
        atomic_set(&bat_priv->bcast_seqno, 1);
        atomic_set(&bat_priv->tt.vn, 0);
        atomic_set(&bat_priv->tt.local_changes, 0);
        atomic_set(&bat_priv->tt.ogm_append_cnt, 0);
#ifdef CONFIG_BATMAN_ADV_BLA
        atomic_set(&bat_priv->bla.num_requests, 0);
#endif
        atomic_set(&bat_priv->tp_num, 0);

        bat_priv->tt.last_changeset = NULL;
        bat_priv->tt.last_changeset_len = 0;
        bat_priv->isolation_mark = 0;
        bat_priv->isolation_mark_mask = 0;

        /* randomize initial seqno to avoid collision */
        get_random_bytes(&random_seqno, sizeof(random_seqno));
        atomic_set(&bat_priv->frag_seqno, random_seqno);

        bat_priv->primary_if = NULL;

        batadv_nc_init_bat_priv(bat_priv);

        ret = batadv_algo_select(bat_priv, batadv_routing_algo);
        if (ret < 0)
                goto free_bat_counters;

        ret = batadv_debugfs_add_meshif(dev);
        if (ret < 0)
                goto free_bat_counters;

        ret = batadv_mesh_init(dev);
        if (ret < 0)
                goto unreg_debugfs;

        return 0;

unreg_debugfs:
        batadv_debugfs_del_meshif(dev);
free_bat_counters:
        free_percpu(bat_priv->bat_counters);
        bat_priv->bat_counters = NULL;

        return ret;
}

/**
 * batadv_softif_slave_add() - Add a slave interface to a batadv_soft_interface
 * @dev: batadv_soft_interface used as master interface
 * @slave_dev: net_device which should become the slave interface
 * @extack: extended ACK report struct
 *
 * Return: 0 if successful or error otherwise.
 */
static int batadv_softif_slave_add(struct net_device *dev,
                                   struct net_device *slave_dev,
                                   struct netlink_ext_ack *extack)
{
        struct batadv_hard_iface *hard_iface;
        struct net *net = dev_net(dev);
        int ret = -EINVAL;

        hard_iface = batadv_hardif_get_by_netdev(slave_dev);
        if (!hard_iface || hard_iface->soft_iface)
                goto out;

        ret = batadv_hardif_enable_interface(hard_iface, net, dev->name);

out:
        if (hard_iface)
                batadv_hardif_put(hard_iface);
        return ret;
}

/**
 * batadv_softif_slave_del() - Delete a slave iface from a batadv_soft_interface
 * @dev: batadv_soft_interface used as master interface
 * @slave_dev: net_device which should be removed from the master interface
 *
 * Return: 0 if successful or error otherwise.
 */
static int batadv_softif_slave_del(struct net_device *dev,
                                   struct net_device *slave_dev)
{
        struct batadv_hard_iface *hard_iface;
        int ret = -EINVAL;

        hard_iface = batadv_hardif_get_by_netdev(slave_dev);

        if (!hard_iface || hard_iface->soft_iface != dev)
                goto out;

        batadv_hardif_disable_interface(hard_iface, BATADV_IF_CLEANUP_KEEP);
        ret = 0;

out:
        if (hard_iface)
                batadv_hardif_put(hard_iface);
        return ret;
}

static const struct net_device_ops batadv_netdev_ops = {
        .ndo_init = batadv_softif_init_late,
        .ndo_open = batadv_interface_open,
        .ndo_stop = batadv_interface_release,
        .ndo_get_stats = batadv_interface_stats,
        .ndo_vlan_rx_add_vid = batadv_interface_add_vid,
        .ndo_vlan_rx_kill_vid = batadv_interface_kill_vid,
        .ndo_set_mac_address = batadv_interface_set_mac_addr,
        .ndo_change_mtu = batadv_interface_change_mtu,
        .ndo_set_rx_mode = batadv_interface_set_rx_mode,
        .ndo_start_xmit = batadv_interface_tx,
        .ndo_validate_addr = eth_validate_addr,
        .ndo_add_slave = batadv_softif_slave_add,
        .ndo_del_slave = batadv_softif_slave_del,
};

static void batadv_get_drvinfo(struct net_device *dev,
                               struct ethtool_drvinfo *info)
{
        strscpy(info->driver, "B.A.T.M.A.N. advanced", sizeof(info->driver));
        strscpy(info->version, BATADV_SOURCE_VERSION, sizeof(info->version));
        strscpy(info->fw_version, "N/A", sizeof(info->fw_version));
        strscpy(info->bus_info, "batman", sizeof(info->bus_info));
}

/* Inspired by drivers/net/ethernet/dlink/sundance.c:1702
 * Declare each description string in struct.name[] to get fixed sized buffer
 * and compile time checking for strings longer than ETH_GSTRING_LEN.
 */
static const struct {
        const char name[ETH_GSTRING_LEN];
} batadv_counters_strings[] = {
        { "tx" },
        { "tx_bytes" },
        { "tx_dropped" },
        { "rx" },
        { "rx_bytes" },
        { "forward" },
        { "forward_bytes" },
        { "mgmt_tx" },
        { "mgmt_tx_bytes" },
        { "mgmt_rx" },
        { "mgmt_rx_bytes" },
        { "frag_tx" },
        { "frag_tx_bytes" },
        { "frag_rx" },
        { "frag_rx_bytes" },
        { "frag_fwd" },
        { "frag_fwd_bytes" },
        { "tt_request_tx" },
        { "tt_request_rx" },
        { "tt_response_tx" },
        { "tt_response_rx" },
        { "tt_roam_adv_tx" },
        { "tt_roam_adv_rx" },
#ifdef CONFIG_BATMAN_ADV_DAT
        { "dat_get_tx" },
        { "dat_get_rx" },
        { "dat_put_tx" },
        { "dat_put_rx" },
        { "dat_cached_reply_tx" },
#endif
#ifdef CONFIG_BATMAN_ADV_NC
        { "nc_code" },
        { "nc_code_bytes" },
        { "nc_recode" },
        { "nc_recode_bytes" },
        { "nc_buffer" },
        { "nc_decode" },
        { "nc_decode_bytes" },
        { "nc_decode_failed" },
        { "nc_sniffed" },
#endif
};

static void batadv_get_strings(struct net_device *dev, u32 stringset, u8 *data)
{
        if (stringset == ETH_SS_STATS)
                memcpy(data, batadv_counters_strings,
                       sizeof(batadv_counters_strings));
}

static void batadv_get_ethtool_stats(struct net_device *dev,
                                     struct ethtool_stats *stats, u64 *data)
{
        struct batadv_priv *bat_priv = netdev_priv(dev);
        int i;

        for (i = 0; i < BATADV_CNT_NUM; i++)
                data[i] = batadv_sum_counter(bat_priv, i);
}

static int batadv_get_sset_count(struct net_device *dev, int stringset)
{
        if (stringset == ETH_SS_STATS)
                return BATADV_CNT_NUM;

        return -EOPNOTSUPP;
}

static const struct ethtool_ops batadv_ethtool_ops = {
        .get_drvinfo = batadv_get_drvinfo,
        .get_link = ethtool_op_get_link,
        .get_strings = batadv_get_strings,
        .get_ethtool_stats = batadv_get_ethtool_stats,
        .get_sset_count = batadv_get_sset_count,
};

/**
 * batadv_softif_free() - Deconstructor of batadv_soft_interface
 * @dev: Device to cleanup and remove
 */
static void batadv_softif_free(struct net_device *dev)
{
        batadv_debugfs_del_meshif(dev);
        batadv_mesh_free(dev);

        /* some scheduled RCU callbacks need the bat_priv struct to accomplish
         * their tasks. Wait for them all to be finished before freeing the
         * netdev and its private data (bat_priv)
         */
        rcu_barrier();
}

/**
 * batadv_softif_init_early() - early stage initialization of soft interface
 * @dev: registered network device to modify
 */
static void batadv_softif_init_early(struct net_device *dev)
{
        ether_setup(dev);

        dev->netdev_ops = &batadv_netdev_ops;
        dev->needs_free_netdev = true;
        dev->priv_destructor = batadv_softif_free;
        dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_NETNS_LOCAL;
        dev->features |= NETIF_F_LLTX;
        dev->priv_flags |= IFF_NO_QUEUE;

        /* can't call min_mtu, because the needed variables
         * have not been initialized yet
         */
        dev->mtu = ETH_DATA_LEN;

        /* generate random address */
        eth_hw_addr_random(dev);

        dev->ethtool_ops = &batadv_ethtool_ops;
}

/**
 * batadv_softif_create() - Create and register soft interface
 * @net: the applicable net namespace
 * @name: name of the new soft interface
 *
 * Return: newly allocated soft_interface, NULL on errors
 */
struct net_device *batadv_softif_create(struct net *net, const char *name)
{
        struct net_device *soft_iface;
        int ret;

        soft_iface = alloc_netdev(sizeof(struct batadv_priv), name,
                                  NET_NAME_UNKNOWN, batadv_softif_init_early);
        if (!soft_iface)
                return NULL;

        dev_net_set(soft_iface, net);

        soft_iface->rtnl_link_ops = &batadv_link_ops;

        ret = register_netdevice(soft_iface);
        if (ret < 0) {
                pr_err("Unable to register the batman interface '%s': %i\n",
                       name, ret);
                free_netdev(soft_iface);
                return NULL;
        }

        return soft_iface;
}

/**
 * batadv_softif_destroy_sysfs() - deletion of batadv_soft_interface via sysfs
 * @soft_iface: the to-be-removed batman-adv interface
 */
void batadv_softif_destroy_sysfs(struct net_device *soft_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        struct batadv_softif_vlan *vlan;

        ASSERT_RTNL();

        /* destroy the "untagged" VLAN */
        vlan = batadv_softif_vlan_get(bat_priv, BATADV_NO_FLAGS);
        if (vlan) {
                batadv_softif_destroy_vlan(bat_priv, vlan);
                batadv_softif_vlan_put(vlan);
        }

        batadv_sysfs_del_meshif(soft_iface);
        unregister_netdevice(soft_iface);
}

/**
 * batadv_softif_destroy_netlink() - deletion of batadv_soft_interface via
 *  netlink
 * @soft_iface: the to-be-removed batman-adv interface
 * @head: list pointer
 */
static void batadv_softif_destroy_netlink(struct net_device *soft_iface,
                                          struct list_head *head)
{
        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        struct batadv_hard_iface *hard_iface;
        struct batadv_softif_vlan *vlan;

        list_for_each_entry(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->soft_iface == soft_iface)
                        batadv_hardif_disable_interface(hard_iface,
                                                        BATADV_IF_CLEANUP_KEEP);
        }

        /* destroy the "untagged" VLAN */
        vlan = batadv_softif_vlan_get(bat_priv, BATADV_NO_FLAGS);
        if (vlan) {
                batadv_softif_destroy_vlan(bat_priv, vlan);
                batadv_softif_vlan_put(vlan);
        }

        batadv_sysfs_del_meshif(soft_iface);
        unregister_netdevice_queue(soft_iface, head);
}

/**
 * batadv_softif_is_valid() - Check whether device is a batadv soft interface
 * @net_dev: device which should be checked
 *
 * Return: true when net_dev is a batman-adv interface, false otherwise
 */
bool batadv_softif_is_valid(const struct net_device *net_dev)
{
        if (net_dev->netdev_ops->ndo_start_xmit == batadv_interface_tx)
                return true;

        return false;
}

struct rtnl_link_ops batadv_link_ops __read_mostly = {
        .kind           = "batadv",
        .priv_size      = sizeof(struct batadv_priv),
        .setup          = batadv_softif_init_early,
        .dellink        = batadv_softif_destroy_netlink,
};