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

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

#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/byteorder/generic.h>
#include <linux/cache.h>
#include <linux/compiler.h>
#include <linux/container_of.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/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/percpu.h>
#include <linux/random.h>
#include <linux/rculist.h>
#include <linux/rcupdate.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 <linux/utsname.h>
#include <net/netlink.h>
#include <net/rtnetlink.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>

#include "bat_algo.h"
#include "bridge_loop_avoidance.h"
#include "distributed-arp-table.h"
#include "gateway_client.h"
#include "hard-interface.h"
#include "multicast.h"
#include "send.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
 *
 * Warning: This function may reallocate the skb data buffer via
 * skb_cow_head()/... Any pointer into the skb data (e.g. obtained
 * from skb->data or eth_hdr()) before this call must be considered
 * invalid afterwards and has to be reacquired.
 *
 * 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;
}

/**
 * batadv_sum_counter() - Sum the cpu-local counters for index 'idx'
 * @bat_priv: the bat priv with all the mesh 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;
	u64 sum = 0;
	int cpu;

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

	return sum;
}

/**
 * batadv_interface_stats() - return netdev stats for a mesh interface
 * @dev: the mesh interface to query
 *
 * Aggregate the per-CPU traffic counters into the standard netdev stats
 * structure.
 *
 * Return: pointer to the populated net_device_stats structure
 */
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;
}

/**
 * batadv_interface_set_mac_addr() - change the MAC address of a mesh
 *  interface
 * @dev: the mesh interface to modify
 * @p: pointer to a struct sockaddr holding the new MAC address
 *
 * Replace the MAC address of the mesh interface. If the mesh is already
 * active, also update the local translation table entries for all configured
 * VLANs so that the new MAC is announced and the old one is removed.
 *
 * Return: 0 on success or negative error number in case of failure
 */
static int batadv_interface_set_mac_addr(struct net_device *dev, void *p)
{
	struct batadv_priv *bat_priv = netdev_priv(dev);
	struct batadv_meshif_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);
	eth_hw_addr_set(dev, addr->sa_data);

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

	rcu_read_lock();
	hlist_for_each_entry_rcu(vlan, &bat_priv->meshif_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;
}

/**
 * batadv_interface_change_mtu() - change the MTU of a mesh interface
 * @dev: the mesh interface to modify
 * @new_mtu: requested new MTU value
 *
 * Validate that @new_mtu fits within the range supported by the configured
 * hard interfaces and remember it as the user-configured MTU.
 *
 * Return: 0 on success or -EINVAL if @new_mtu is out of range
 */
static int batadv_interface_change_mtu(struct net_device *dev, int new_mtu)
{
	struct batadv_priv *bat_priv = netdev_priv(dev);

	/* check ranges */
	if (new_mtu < ETH_MIN_MTU || new_mtu > batadv_hardif_min_mtu(dev))
		return -EINVAL;

	WRITE_ONCE(dev->mtu, new_mtu);
	bat_priv->mtu_set_by_user = 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
 * mesh 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)
{
}

/**
 * batadv_interface_tx() - transmit a frame on a mesh interface
 * @skb: the frame to send
 * @mesh_iface: the mesh interface the frame was queued on
 *
 * Return: NETDEV_TX_OK on success
 */
static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
				       struct net_device *mesh_iface)
{
	static const u8 ectp_addr[ETH_ALEN] = {0xCF, 0x00, 0x00, 0x00, 0x00, 0x00};
	static const u8 stp_addr[ETH_ALEN] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x00};
	struct batadv_priv *bat_priv = netdev_priv(mesh_iface);
	enum batadv_dhcp_recipient dhcp_rcp = BATADV_DHCP_NO;
	enum batadv_forw_mode forw_mode = BATADV_FORW_BCAST;
	struct batadv_hard_iface *primary_if = NULL;
	struct batadv_bcast_packet *bcast_packet;
	int network_offset = ETH_HLEN;
	unsigned int header_len = 0;
	unsigned long brd_delay = 0;
	int mcast_is_routable = 0;
	struct vlan_ethhdr *vhdr;
	int data_len = skb->len;
	struct ethhdr *ethhdr;
	bool do_bcast = false;
	u8 *dst_hint = NULL;
	u8 chaddr[ETH_ALEN];
	unsigned short vid;
	bool client_added;
	__be16 proto;
	int gw_mode;
	u32 seqno;
	int ret;

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

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

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

	netif_trans_update(mesh_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(mesh_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;

	batadv_skb_set_priority(skb, 0);

	gw_mode = READ_ONCE(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)) {
			/* WARNING batadv_mcast_forw_mode might add more headers
			 * in front of the skb. and might even reallocate the skb
			 */
			forw_mode = batadv_mcast_forw_mode(bat_priv, skb, vid,
							   &mcast_is_routable);
			switch (forw_mode) {
			case BATADV_FORW_BCAST:
				break;
			case BATADV_FORW_UCASTS:
			case BATADV_FORW_MCAST:
				do_bcast = false;
				break;
			case BATADV_FORW_NONE:
				fallthrough;
			default:
				goto dropped;
			}
		}
	}

	/* 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 - 1;

		/* 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_send_bcast_packet(bat_priv, skb, brd_delay, true);
	/* 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 (forw_mode == BATADV_FORW_UCASTS) {
			ret = batadv_mcast_forw_send(bat_priv, skb, vid,
						     mcast_is_routable);
		} else if (forw_mode == BATADV_FORW_MCAST) {
			ret = batadv_mcast_forw_mcsend(bat_priv, skb);
		} 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:
	batadv_hardif_put(primary_if);
	return NETDEV_TX_OK;
}

/**
 * batadv_interface_rx() - receive ethernet frame on local batman-adv interface
 * @mesh_iface: local interface which will receive the ethernet frame
 * @skb: ethernet frame for @mesh_iface
 * @hdr_size: size of already parsed batman-adv header
 * @orig_node: originator from which the batman-adv packet was sent
 *
 * Sends an ethernet frame to the receive path of the local @mesh_iface.
 * skb->data must 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 a batman-adv packet. Also
 * unicast packets will be dropped directly when they were sent between two
 * isolated clients.
 */
void batadv_interface_rx(struct net_device *mesh_iface,
			 struct sk_buff *skb, int hdr_size,
			 struct batadv_orig_node *orig_node)
{
	struct batadv_priv *bat_priv = netdev_priv(mesh_iface);
	struct batadv_bcast_packet *batadv_bcast_packet;
	struct vlan_ethhdr *vhdr;
	struct ethhdr *ethhdr;
	unsigned short vid;
	int packet_type;

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

	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;

		ethhdr = eth_hdr(skb);
		vhdr = skb_vlan_eth_hdr(skb);

		/* 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, mesh_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, packet_type))
		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_meshif_vlan_release() - release vlan from lists and queue for free
 *  after rcu grace period
 * @ref: kref pointer of the vlan object
 */
void batadv_meshif_vlan_release(struct kref *ref)
{
	struct batadv_meshif_vlan *vlan;

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

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

	kfree_rcu(vlan, rcu);
}

/**
 * batadv_meshif_vlan_get() - get the vlan object for a specific vid
 * @bat_priv: the bat priv with all the mesh 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_meshif_vlan *batadv_meshif_vlan_get(struct batadv_priv *bat_priv,
						  unsigned short vid)
{
	struct batadv_meshif_vlan *vlan = NULL;
	struct batadv_meshif_vlan *vlan_tmp;

	rcu_read_lock();
	hlist_for_each_entry_rcu(vlan_tmp, &bat_priv->meshif_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_meshif_create_vlan() - allocate the needed resources for a new vlan
 * @bat_priv: the bat priv with all the mesh interface information
 * @vid: the VLAN identifier
 *
 * Return: 0 on success, a negative error otherwise.
 */
int batadv_meshif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
{
	struct batadv_meshif_vlan *vlan;

	spin_lock_bh(&bat_priv->meshif_vlan_list_lock);

	vlan = batadv_meshif_vlan_get(bat_priv, vid);
	if (vlan) {
		batadv_meshif_vlan_put(vlan);
		spin_unlock_bh(&bat_priv->meshif_vlan_list_lock);
		return -EEXIST;
	}

	vlan = kzalloc_obj(*vlan, GFP_ATOMIC);
	if (!vlan) {
		spin_unlock_bh(&bat_priv->meshif_vlan_list_lock);
		return -ENOMEM;
	}

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

	WRITE_ONCE(vlan->ap_isolation, 0);

	kref_get(&vlan->refcount);
	hlist_add_head_rcu(&vlan->list, &bat_priv->meshif_vlan_list);
	spin_unlock_bh(&bat_priv->meshif_vlan_list_lock);

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

	/* don't return reference to new meshif_vlan */
	batadv_meshif_vlan_put(vlan);

	return 0;
}

/**
 * batadv_meshif_destroy_vlan() - remove and destroy a meshif_vlan object
 * @bat_priv: the bat priv with all the mesh interface information
 * @vlan: the object to remove
 */
void batadv_meshif_destroy_vlan(struct batadv_priv *bat_priv,
				struct batadv_meshif_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->mesh_iface->dev_addr,
			       vlan->vid, "vlan interface destroyed", false);

	batadv_meshif_vlan_put(vlan);
}

/**
 * batadv_interface_add_vid() - ndo_add_vid API implementation
 * @dev: the netdev of the mesh interface
 * @proto: protocol of 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_meshif_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;

	/* VID 0 is only used to indicate "priority tag" frames which only
	 * contain priority information and no VID. No management structures
	 * should be created for this VID and it should be handled like an
	 * untagged frame.
	 */
	if (vid == 0)
		return 0;

	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_meshif_vlan_get() increases the
	 * refcount in order to revive the object.
	 *
	 * if it does not exist then create it.
	 */
	vlan = batadv_meshif_vlan_get(bat_priv, vid);
	if (!vlan)
		return batadv_meshif_create_vlan(bat_priv, vid);

	/* 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->mesh_iface,
			    bat_priv->mesh_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 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_meshif_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;

	/* "priority tag" frames are handled like "untagged" frames
	 * and no meshif_vlan needs to be destroyed
	 */
	if (vid == 0)
		return 0;

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

	batadv_meshif_destroy_vlan(bat_priv, vlan);

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

	return 0;
}

/* batman-adv network devices have devices nesting below it and are a special
 * "super class" of normal network devices; split their locks off into a
 * separate class since they always nest.
 */
static struct lock_class_key batadv_netdev_xmit_lock_key;
static struct lock_class_key batadv_netdev_addr_lock_key;

/**
 * batadv_set_lockdep_class_one() - Set lockdep class for a single tx queue
 * @dev: device which owns the tx queue
 * @txq: tx queue to modify
 * @_unused: always NULL
 */
static void batadv_set_lockdep_class_one(struct net_device *dev,
					 struct netdev_queue *txq,
					 void *_unused)
{
	lockdep_set_class(&txq->_xmit_lock, &batadv_netdev_xmit_lock_key);
}

/**
 * batadv_set_lockdep_class() - Set txq and addr_list lockdep class
 * @dev: network device to modify
 */
static void batadv_set_lockdep_class(struct net_device *dev)
{
	lockdep_set_class(&dev->addr_list_lock, &batadv_netdev_addr_lock_key);
	netdev_for_each_tx_queue(dev, batadv_set_lockdep_class_one, NULL);
}

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

	batadv_set_lockdep_class(dev);

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

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

	WRITE_ONCE(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.ogm_append_cnt, 0);
#ifdef CONFIG_BATMAN_ADV_BLA
	atomic_set(&bat_priv->bla.num_requests, 0);
	spin_lock_init(&bat_priv->bla.num_requests_lock);
#endif
	atomic_set(&bat_priv->tp_num, 0);

	WRITE_ONCE(bat_priv->tt.local_changes, 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;

	if (!bat_priv->algo_ops) {
		ret = batadv_algo_select(bat_priv, batadv_routing_algo);
		if (ret < 0)
			goto free_bat_counters;
	}

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

	return 0;

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

	return ret;
}

/**
 * batadv_meshif_slave_add() - Add a slave interface to a batadv_mesh_interface
 * @dev: batadv_mesh_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_meshif_slave_add(struct net_device *dev,
				   struct net_device *slave_dev,
				   struct netlink_ext_ack *extack)
{
	return batadv_hardif_enable_interface(slave_dev, dev);
}

/**
 * batadv_meshif_slave_del() - Delete a slave iface from a batadv_mesh_interface
 * @dev: batadv_mesh_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_meshif_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->mesh_iface != dev)
		goto out;

	batadv_hardif_disable_interface(hard_iface);
	ret = 0;

out:
	batadv_hardif_put(hard_iface);
	return ret;
}

static const struct net_device_ops batadv_netdev_ops = {
	.ndo_init = batadv_meshif_init_late,
	.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_meshif_slave_add,
	.ndo_del_slave = batadv_meshif_slave_del,
};

/**
 * batadv_get_drvinfo() - ethtool driver info handler for mesh interfaces
 * @dev: the mesh interface (unused)
 * @info: ethtool_drvinfo struct to populate
 */
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, init_utsname()->release, 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_MCAST
	{ "mcast_tx" },
	{ "mcast_tx_bytes" },
	{ "mcast_tx_local" },
	{ "mcast_tx_local_bytes" },
	{ "mcast_rx" },
	{ "mcast_rx_bytes" },
	{ "mcast_rx_local" },
	{ "mcast_rx_local_bytes" },
	{ "mcast_fwd" },
	{ "mcast_fwd_bytes" },
#endif
#ifdef CONFIG_BATMAN_ADV_DAT
	{ "dat_get_tx" },
	{ "dat_get_rx" },
	{ "dat_put_tx" },
	{ "dat_put_rx" },
	{ "dat_cached_reply_tx" },
#endif
};

/**
 * batadv_get_strings() - ethtool string handler for mesh interfaces
 * @dev: the mesh interface (unused)
 * @stringset: ethtool string set to retrieve
 * @data: buffer to copy the requested string set into
 */
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));
}

/**
 * batadv_get_ethtool_stats() - ethtool stats handler for mesh interfaces
 * @dev: the mesh interface to query
 * @stats: ethtool_stats struct (unused)
 * @data: destination array for the gathered counter values
 */
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);
}

/**
 * batadv_get_sset_count() - ethtool stringset size handler for mesh interfaces
 * @dev: the mesh interface (unused)
 * @stringset: ethtool string set to query
 *
 * Return: number of entries in @stringset or -EOPNOTSUPP if @stringset is not
 *  supported
 */
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_meshif_free() - Deconstructor of batadv_mesh_interface
 * @dev: Device to cleanup and remove
 */
static void batadv_meshif_free(struct net_device *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_meshif_init_early() - early stage initialization of mesh interface
 * @dev: registered network device to modify
 */
static void batadv_meshif_init_early(struct net_device *dev)
{
	ether_setup(dev);

	dev->netdev_ops = &batadv_netdev_ops;
	dev->needs_free_netdev = true;
	dev->priv_destructor = batadv_meshif_free;
	dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
	dev->priv_flags |= IFF_NO_QUEUE;
	dev->lltx = true;
	dev->netns_immutable = true;

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

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

	dev->ethtool_ops = &batadv_ethtool_ops;
}

/**
 * batadv_meshif_validate() - validate configuration of new batadv link
 * @tb: IFLA_INFO_DATA netlink attributes
 * @data: enum batadv_ifla_attrs attributes
 * @extack: extended ACK report struct
 *
 * Return: 0 if successful or error otherwise.
 */
static int batadv_meshif_validate(struct nlattr *tb[], struct nlattr *data[],
				  struct netlink_ext_ack *extack)
{
	struct batadv_algo_ops *algo_ops;

	if (!data)
		return 0;

	if (data[IFLA_BATADV_ALGO_NAME]) {
		algo_ops = batadv_algo_get(nla_data(data[IFLA_BATADV_ALGO_NAME]));
		if (!algo_ops)
			return -EINVAL;
	}

	return 0;
}

/**
 * batadv_meshif_newlink() - pre-initialize and register new batadv link
 * @dev: network device to register
 * @params: rtnl newlink parameters
 * @extack: extended ACK report struct
 *
 * Return: 0 if successful or error otherwise.
 */
static int batadv_meshif_newlink(struct net_device *dev,
				 struct rtnl_newlink_params *params,
				 struct netlink_ext_ack *extack)
{
	struct batadv_priv *bat_priv = netdev_priv(dev);
	struct nlattr **data = params->data;
	const char *algo_name;
	int err;

	if (data && data[IFLA_BATADV_ALGO_NAME]) {
		algo_name = nla_data(data[IFLA_BATADV_ALGO_NAME]);
		err = batadv_algo_select(bat_priv, algo_name);
		if (err)
			return -EINVAL;
	}

	return register_netdevice(dev);
}

/**
 * batadv_meshif_destroy_netlink() - deletion of batadv_mesh_interface via
 *  netlink
 * @mesh_iface: the to-be-removed batman-adv interface
 * @head: list pointer
 */
static void batadv_meshif_destroy_netlink(struct net_device *mesh_iface,
					  struct list_head *head)
{
	struct batadv_hard_iface *hard_iface;

	while (!list_empty(&mesh_iface->adj_list.lower)) {
		hard_iface = netdev_adjacent_get_private(mesh_iface->adj_list.lower.next);
		batadv_hardif_disable_interface(hard_iface);
	}

	unregister_netdevice_queue(mesh_iface, head);
}

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

	return false;
}

static const struct nla_policy batadv_ifla_policy[IFLA_BATADV_MAX + 1] = {
	[IFLA_BATADV_ALGO_NAME]	= { .type = NLA_NUL_STRING },
};

struct rtnl_link_ops batadv_link_ops __read_mostly = {
	.kind		= "batadv",
	.priv_size	= sizeof(struct batadv_priv),
	.setup		= batadv_meshif_init_early,
	.maxtype	= IFLA_BATADV_MAX,
	.policy		= batadv_ifla_policy,
	.validate	= batadv_meshif_validate,
	.newlink	= batadv_meshif_newlink,
	.dellink	= batadv_meshif_destroy_netlink,
};