Merge tag 'iommu-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

[linux/fpc-iii.git] / net / batman-adv / multicast.c

// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2014-2020  B.A.T.M.A.N. contributors:
 *
 * Linus Lüssing
 */

#include "multicast.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/byteorder/generic.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/gfp.h>
#include <linux/icmpv6.h>
#include <linux/if_bridge.h>
#include <linux/if_ether.h>
#include <linux/igmp.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/printk.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <net/addrconf.h>
#include <net/genetlink.h>
#include <net/if_inet6.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/netlink.h>
#include <net/sock.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>

#include "bridge_loop_avoidance.h"
#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "netlink.h"
#include "send.h"
#include "soft-interface.h"
#include "translation-table.h"
#include "tvlv.h"

static void batadv_mcast_mla_update(struct work_struct *work);

/**
 * batadv_mcast_start_timer() - schedule the multicast periodic worker
 * @bat_priv: the bat priv with all the soft interface information
 */
static void batadv_mcast_start_timer(struct batadv_priv *bat_priv)
{
        queue_delayed_work(batadv_event_workqueue, &bat_priv->mcast.work,
                           msecs_to_jiffies(BATADV_MCAST_WORK_PERIOD));
}

/**
 * batadv_mcast_get_bridge() - get the bridge on top of the softif if it exists
 * @soft_iface: netdev struct of the mesh interface
 *
 * If the given soft interface has a bridge on top then the refcount
 * of the according net device is increased.
 *
 * Return: NULL if no such bridge exists. Otherwise the net device of the
 * bridge.
 */
static struct net_device *batadv_mcast_get_bridge(struct net_device *soft_iface)
{
        struct net_device *upper = soft_iface;

        rcu_read_lock();
        do {
                upper = netdev_master_upper_dev_get_rcu(upper);
        } while (upper && !(upper->priv_flags & IFF_EBRIDGE));

        if (upper)
                dev_hold(upper);
        rcu_read_unlock();

        return upper;
}

/**
 * batadv_mcast_mla_rtr_flags_softif_get_ipv4() - get mcast router flags from
 *  node for IPv4
 * @dev: the interface to check
 *
 * Checks the presence of an IPv4 multicast router on this node.
 *
 * Caller needs to hold rcu read lock.
 *
 * Return: BATADV_NO_FLAGS if present, BATADV_MCAST_WANT_NO_RTR4 otherwise.
 */
static u8 batadv_mcast_mla_rtr_flags_softif_get_ipv4(struct net_device *dev)
{
        struct in_device *in_dev = __in_dev_get_rcu(dev);

        if (in_dev && IN_DEV_MFORWARD(in_dev))
                return BATADV_NO_FLAGS;
        else
                return BATADV_MCAST_WANT_NO_RTR4;
}

/**
 * batadv_mcast_mla_rtr_flags_softif_get_ipv6() - get mcast router flags from
 *  node for IPv6
 * @dev: the interface to check
 *
 * Checks the presence of an IPv6 multicast router on this node.
 *
 * Caller needs to hold rcu read lock.
 *
 * Return: BATADV_NO_FLAGS if present, BATADV_MCAST_WANT_NO_RTR6 otherwise.
 */
#if IS_ENABLED(CONFIG_IPV6_MROUTE)
static u8 batadv_mcast_mla_rtr_flags_softif_get_ipv6(struct net_device *dev)
{
        struct inet6_dev *in6_dev = __in6_dev_get(dev);

        if (in6_dev && in6_dev->cnf.mc_forwarding)
                return BATADV_NO_FLAGS;
        else
                return BATADV_MCAST_WANT_NO_RTR6;
}
#else
static inline u8
batadv_mcast_mla_rtr_flags_softif_get_ipv6(struct net_device *dev)
{
        return BATADV_MCAST_WANT_NO_RTR6;
}
#endif

/**
 * batadv_mcast_mla_rtr_flags_softif_get() - get mcast router flags from node
 * @bat_priv: the bat priv with all the soft interface information
 * @bridge: bridge interface on top of the soft_iface if present,
 *  otherwise pass NULL
 *
 * Checks the presence of IPv4 and IPv6 multicast routers on this
 * node.
 *
 * Return:
 *      BATADV_NO_FLAGS: Both an IPv4 and IPv6 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR4: No IPv4 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR6: No IPv6 multicast router is present
 *      The former two OR'd: no multicast router is present
 */
static u8 batadv_mcast_mla_rtr_flags_softif_get(struct batadv_priv *bat_priv,
                                                struct net_device *bridge)
{
        struct net_device *dev = bridge ? bridge : bat_priv->soft_iface;
        u8 flags = BATADV_NO_FLAGS;

        rcu_read_lock();

        flags |= batadv_mcast_mla_rtr_flags_softif_get_ipv4(dev);
        flags |= batadv_mcast_mla_rtr_flags_softif_get_ipv6(dev);

        rcu_read_unlock();

        return flags;
}

/**
 * batadv_mcast_mla_rtr_flags_bridge_get() - get mcast router flags from bridge
 * @bat_priv: the bat priv with all the soft interface information
 * @bridge: bridge interface on top of the soft_iface if present,
 *  otherwise pass NULL
 *
 * Checks the presence of IPv4 and IPv6 multicast routers behind a bridge.
 *
 * Return:
 *      BATADV_NO_FLAGS: Both an IPv4 and IPv6 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR4: No IPv4 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR6: No IPv6 multicast router is present
 *      The former two OR'd: no multicast router is present
 */
#if IS_ENABLED(CONFIG_IPV6)
static u8 batadv_mcast_mla_rtr_flags_bridge_get(struct batadv_priv *bat_priv,
                                                struct net_device *bridge)
{
        struct list_head bridge_mcast_list = LIST_HEAD_INIT(bridge_mcast_list);
        struct net_device *dev = bat_priv->soft_iface;
        struct br_ip_list *br_ip_entry, *tmp;
        u8 flags = BATADV_MCAST_WANT_NO_RTR6;
        int ret;

        if (!bridge)
                return BATADV_MCAST_WANT_NO_RTR4 | BATADV_MCAST_WANT_NO_RTR6;

        /* TODO: ask the bridge if a multicast router is present (the bridge
         * is capable of performing proper RFC4286 multicast router
         * discovery) instead of searching for a ff02::2 listener here
         */
        ret = br_multicast_list_adjacent(dev, &bridge_mcast_list);
        if (ret < 0)
                return BATADV_NO_FLAGS;

        list_for_each_entry_safe(br_ip_entry, tmp, &bridge_mcast_list, list) {
                /* the bridge snooping does not maintain IPv4 link-local
                 * addresses - therefore we won't find any IPv4 multicast router
                 * address here, only IPv6 ones
                 */
                if (br_ip_entry->addr.proto == htons(ETH_P_IPV6) &&
                    ipv6_addr_is_ll_all_routers(&br_ip_entry->addr.dst.ip6))
                        flags &= ~BATADV_MCAST_WANT_NO_RTR6;

                list_del(&br_ip_entry->list);
                kfree(br_ip_entry);
        }

        return flags;
}
#else
static inline u8
batadv_mcast_mla_rtr_flags_bridge_get(struct batadv_priv *bat_priv,
                                      struct net_device *bridge)
{
        if (bridge)
                return BATADV_NO_FLAGS;
        else
                return BATADV_MCAST_WANT_NO_RTR4 | BATADV_MCAST_WANT_NO_RTR6;
}
#endif

/**
 * batadv_mcast_mla_rtr_flags_get() - get multicast router flags
 * @bat_priv: the bat priv with all the soft interface information
 * @bridge: bridge interface on top of the soft_iface if present,
 *  otherwise pass NULL
 *
 * Checks the presence of IPv4 and IPv6 multicast routers on this
 * node or behind its bridge.
 *
 * Return:
 *      BATADV_NO_FLAGS: Both an IPv4 and IPv6 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR4: No IPv4 multicast router is present
 *      BATADV_MCAST_WANT_NO_RTR6: No IPv6 multicast router is present
 *      The former two OR'd: no multicast router is present
 */
static u8 batadv_mcast_mla_rtr_flags_get(struct batadv_priv *bat_priv,
                                         struct net_device *bridge)
{
        u8 flags = BATADV_MCAST_WANT_NO_RTR4 | BATADV_MCAST_WANT_NO_RTR6;

        flags &= batadv_mcast_mla_rtr_flags_softif_get(bat_priv, bridge);
        flags &= batadv_mcast_mla_rtr_flags_bridge_get(bat_priv, bridge);

        return flags;
}

/**
 * batadv_mcast_mla_flags_get() - get the new multicast flags
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: A set of flags for the current/next TVLV, querier and
 * bridge state.
 */
static struct batadv_mcast_mla_flags
batadv_mcast_mla_flags_get(struct batadv_priv *bat_priv)
{
        struct net_device *dev = bat_priv->soft_iface;
        struct batadv_mcast_querier_state *qr4, *qr6;
        struct batadv_mcast_mla_flags mla_flags;
        struct net_device *bridge;

        bridge = batadv_mcast_get_bridge(dev);

        memset(&mla_flags, 0, sizeof(mla_flags));
        mla_flags.enabled = 1;
        mla_flags.tvlv_flags |= batadv_mcast_mla_rtr_flags_get(bat_priv,
                                                               bridge);

        if (!bridge)
                return mla_flags;

        dev_put(bridge);

        mla_flags.bridged = 1;
        qr4 = &mla_flags.querier_ipv4;
        qr6 = &mla_flags.querier_ipv6;

        if (!IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING))
                pr_warn_once("No bridge IGMP snooping compiled - multicast optimizations disabled\n");

        qr4->exists = br_multicast_has_querier_anywhere(dev, ETH_P_IP);
        qr4->shadowing = br_multicast_has_querier_adjacent(dev, ETH_P_IP);

        qr6->exists = br_multicast_has_querier_anywhere(dev, ETH_P_IPV6);
        qr6->shadowing = br_multicast_has_querier_adjacent(dev, ETH_P_IPV6);

        mla_flags.tvlv_flags |= BATADV_MCAST_WANT_ALL_UNSNOOPABLES;

        /* 1) If no querier exists at all, then multicast listeners on
         *    our local TT clients behind the bridge will keep silent.
         * 2) If the selected querier is on one of our local TT clients,
         *    behind the bridge, then this querier might shadow multicast
         *    listeners on our local TT clients, behind this bridge.
         *
         * In both cases, we will signalize other batman nodes that
         * we need all multicast traffic of the according protocol.
         */
        if (!qr4->exists || qr4->shadowing) {
                mla_flags.tvlv_flags |= BATADV_MCAST_WANT_ALL_IPV4;
                mla_flags.tvlv_flags &= ~BATADV_MCAST_WANT_NO_RTR4;
        }

        if (!qr6->exists || qr6->shadowing) {
                mla_flags.tvlv_flags |= BATADV_MCAST_WANT_ALL_IPV6;
                mla_flags.tvlv_flags &= ~BATADV_MCAST_WANT_NO_RTR6;
        }

        return mla_flags;
}

/**
 * batadv_mcast_mla_is_duplicate() - check whether an address is in a list
 * @mcast_addr: the multicast address to check
 * @mcast_list: the list with multicast addresses to search in
 *
 * Return: true if the given address is already in the given list.
 * Otherwise returns false.
 */
static bool batadv_mcast_mla_is_duplicate(u8 *mcast_addr,
                                          struct hlist_head *mcast_list)
{
        struct batadv_hw_addr *mcast_entry;

        hlist_for_each_entry(mcast_entry, mcast_list, list)
                if (batadv_compare_eth(mcast_entry->addr, mcast_addr))
                        return true;

        return false;
}

/**
 * batadv_mcast_mla_softif_get_ipv4() - get softif IPv4 multicast listeners
 * @dev: the device to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 * @flags: flags indicating the new multicast state
 *
 * Collects multicast addresses of IPv4 multicast listeners residing
 * on this kernel on the given soft interface, dev, in
 * the given mcast_list. In general, multicast listeners provided by
 * your multicast receiving applications run directly on this node.
 *
 * Return: -ENOMEM on memory allocation error or the number of
 * items added to the mcast_list otherwise.
 */
static int
batadv_mcast_mla_softif_get_ipv4(struct net_device *dev,
                                 struct hlist_head *mcast_list,
                                 struct batadv_mcast_mla_flags *flags)
{
        struct batadv_hw_addr *new;
        struct in_device *in_dev;
        u8 mcast_addr[ETH_ALEN];
        struct ip_mc_list *pmc;
        int ret = 0;

        if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_IPV4)
                return 0;

        rcu_read_lock();

        in_dev = __in_dev_get_rcu(dev);
        if (!in_dev) {
                rcu_read_unlock();
                return 0;
        }

        for (pmc = rcu_dereference(in_dev->mc_list); pmc;
             pmc = rcu_dereference(pmc->next_rcu)) {
                if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
                    ipv4_is_local_multicast(pmc->multiaddr))
                        continue;

                if (!(flags->tvlv_flags & BATADV_MCAST_WANT_NO_RTR4) &&
                    !ipv4_is_local_multicast(pmc->multiaddr))
                        continue;

                ip_eth_mc_map(pmc->multiaddr, mcast_addr);

                if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
                        continue;

                new = kmalloc(sizeof(*new), GFP_ATOMIC);
                if (!new) {
                        ret = -ENOMEM;
                        break;
                }

                ether_addr_copy(new->addr, mcast_addr);
                hlist_add_head(&new->list, mcast_list);
                ret++;
        }
        rcu_read_unlock();

        return ret;
}

/**
 * batadv_mcast_mla_softif_get_ipv6() - get softif IPv6 multicast listeners
 * @dev: the device to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 * @flags: flags indicating the new multicast state
 *
 * Collects multicast addresses of IPv6 multicast listeners residing
 * on this kernel on the given soft interface, dev, in
 * the given mcast_list. In general, multicast listeners provided by
 * your multicast receiving applications run directly on this node.
 *
 * Return: -ENOMEM on memory allocation error or the number of
 * items added to the mcast_list otherwise.
 */
#if IS_ENABLED(CONFIG_IPV6)
static int
batadv_mcast_mla_softif_get_ipv6(struct net_device *dev,
                                 struct hlist_head *mcast_list,
                                 struct batadv_mcast_mla_flags *flags)
{
        struct batadv_hw_addr *new;
        struct inet6_dev *in6_dev;
        u8 mcast_addr[ETH_ALEN];
        struct ifmcaddr6 *pmc6;
        int ret = 0;

        if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_IPV6)
                return 0;

        rcu_read_lock();

        in6_dev = __in6_dev_get(dev);
        if (!in6_dev) {
                rcu_read_unlock();
                return 0;
        }

        read_lock_bh(&in6_dev->lock);
        for (pmc6 = in6_dev->mc_list; pmc6; pmc6 = pmc6->next) {
                if (IPV6_ADDR_MC_SCOPE(&pmc6->mca_addr) <
                    IPV6_ADDR_SCOPE_LINKLOCAL)
                        continue;

                if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
                    ipv6_addr_is_ll_all_nodes(&pmc6->mca_addr))
                        continue;

                if (!(flags->tvlv_flags & BATADV_MCAST_WANT_NO_RTR6) &&
                    IPV6_ADDR_MC_SCOPE(&pmc6->mca_addr) >
                    IPV6_ADDR_SCOPE_LINKLOCAL)
                        continue;

                ipv6_eth_mc_map(&pmc6->mca_addr, mcast_addr);

                if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
                        continue;

                new = kmalloc(sizeof(*new), GFP_ATOMIC);
                if (!new) {
                        ret = -ENOMEM;
                        break;
                }

                ether_addr_copy(new->addr, mcast_addr);
                hlist_add_head(&new->list, mcast_list);
                ret++;
        }
        read_unlock_bh(&in6_dev->lock);
        rcu_read_unlock();

        return ret;
}
#else
static inline int
batadv_mcast_mla_softif_get_ipv6(struct net_device *dev,
                                 struct hlist_head *mcast_list,
                                 struct batadv_mcast_mla_flags *flags)
{
        return 0;
}
#endif

/**
 * batadv_mcast_mla_softif_get() - get softif multicast listeners
 * @dev: the device to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 * @flags: flags indicating the new multicast state
 *
 * Collects multicast addresses of multicast listeners residing
 * on this kernel on the given soft interface, dev, in
 * the given mcast_list. In general, multicast listeners provided by
 * your multicast receiving applications run directly on this node.
 *
 * If there is a bridge interface on top of dev, collect from that one
 * instead. Just like with IP addresses and routes, multicast listeners
 * will(/should) register to the bridge interface instead of an
 * enslaved bat0.
 *
 * Return: -ENOMEM on memory allocation error or the number of
 * items added to the mcast_list otherwise.
 */
static int
batadv_mcast_mla_softif_get(struct net_device *dev,
                            struct hlist_head *mcast_list,
                            struct batadv_mcast_mla_flags *flags)
{
        struct net_device *bridge = batadv_mcast_get_bridge(dev);
        int ret4, ret6 = 0;

        if (bridge)
                dev = bridge;

        ret4 = batadv_mcast_mla_softif_get_ipv4(dev, mcast_list, flags);
        if (ret4 < 0)
                goto out;

        ret6 = batadv_mcast_mla_softif_get_ipv6(dev, mcast_list, flags);
        if (ret6 < 0) {
                ret4 = 0;
                goto out;
        }

out:
        if (bridge)
                dev_put(bridge);

        return ret4 + ret6;
}

/**
 * batadv_mcast_mla_br_addr_cpy() - copy a bridge multicast address
 * @dst: destination to write to - a multicast MAC address
 * @src: source to read from - a multicast IP address
 *
 * Converts a given multicast IPv4/IPv6 address from a bridge
 * to its matching multicast MAC address and copies it into the given
 * destination buffer.
 *
 * Caller needs to make sure the destination buffer can hold
 * at least ETH_ALEN bytes.
 */
static void batadv_mcast_mla_br_addr_cpy(char *dst, const struct br_ip *src)
{
        if (src->proto == htons(ETH_P_IP))
                ip_eth_mc_map(src->dst.ip4, dst);
#if IS_ENABLED(CONFIG_IPV6)
        else if (src->proto == htons(ETH_P_IPV6))
                ipv6_eth_mc_map(&src->dst.ip6, dst);
#endif
        else
                eth_zero_addr(dst);
}

/**
 * batadv_mcast_mla_bridge_get() - get bridged-in multicast listeners
 * @dev: a bridge slave whose bridge to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 * @flags: flags indicating the new multicast state
 *
 * Collects multicast addresses of multicast listeners residing
 * on foreign, non-mesh devices which we gave access to our mesh via
 * a bridge on top of the given soft interface, dev, in the given
 * mcast_list.
 *
 * Return: -ENOMEM on memory allocation error or the number of
 * items added to the mcast_list otherwise.
 */
static int batadv_mcast_mla_bridge_get(struct net_device *dev,
                                       struct hlist_head *mcast_list,
                                       struct batadv_mcast_mla_flags *flags)
{
        struct list_head bridge_mcast_list = LIST_HEAD_INIT(bridge_mcast_list);
        struct br_ip_list *br_ip_entry, *tmp;
        u8 tvlv_flags = flags->tvlv_flags;
        struct batadv_hw_addr *new;
        u8 mcast_addr[ETH_ALEN];
        int ret;

        /* we don't need to detect these devices/listeners, the IGMP/MLD
         * snooping code of the Linux bridge already does that for us
         */
        ret = br_multicast_list_adjacent(dev, &bridge_mcast_list);
        if (ret < 0)
                goto out;

        list_for_each_entry(br_ip_entry, &bridge_mcast_list, list) {
                if (br_ip_entry->addr.proto == htons(ETH_P_IP)) {
                        if (tvlv_flags & BATADV_MCAST_WANT_ALL_IPV4)
                                continue;

                        if (tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
                            ipv4_is_local_multicast(br_ip_entry->addr.dst.ip4))
                                continue;

                        if (!(tvlv_flags & BATADV_MCAST_WANT_NO_RTR4) &&
                            !ipv4_is_local_multicast(br_ip_entry->addr.dst.ip4))
                                continue;
                }

#if IS_ENABLED(CONFIG_IPV6)
                if (br_ip_entry->addr.proto == htons(ETH_P_IPV6)) {
                        if (tvlv_flags & BATADV_MCAST_WANT_ALL_IPV6)
                                continue;

                        if (tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
                            ipv6_addr_is_ll_all_nodes(&br_ip_entry->addr.dst.ip6))
                                continue;

                        if (!(tvlv_flags & BATADV_MCAST_WANT_NO_RTR6) &&
                            IPV6_ADDR_MC_SCOPE(&br_ip_entry->addr.dst.ip6) >
                            IPV6_ADDR_SCOPE_LINKLOCAL)
                                continue;
                }
#endif

                batadv_mcast_mla_br_addr_cpy(mcast_addr, &br_ip_entry->addr);
                if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
                        continue;

                new = kmalloc(sizeof(*new), GFP_ATOMIC);
                if (!new) {
                        ret = -ENOMEM;
                        break;
                }

                ether_addr_copy(new->addr, mcast_addr);
                hlist_add_head(&new->list, mcast_list);
        }

out:
        list_for_each_entry_safe(br_ip_entry, tmp, &bridge_mcast_list, list) {
                list_del(&br_ip_entry->list);
                kfree(br_ip_entry);
        }

        return ret;
}

/**
 * batadv_mcast_mla_list_free() - free a list of multicast addresses
 * @mcast_list: the list to free
 *
 * Removes and frees all items in the given mcast_list.
 */
static void batadv_mcast_mla_list_free(struct hlist_head *mcast_list)
{
        struct batadv_hw_addr *mcast_entry;
        struct hlist_node *tmp;

        hlist_for_each_entry_safe(mcast_entry, tmp, mcast_list, list) {
                hlist_del(&mcast_entry->list);
                kfree(mcast_entry);
        }
}

/**
 * batadv_mcast_mla_tt_retract() - clean up multicast listener announcements
 * @bat_priv: the bat priv with all the soft interface information
 * @mcast_list: a list of addresses which should _not_ be removed
 *
 * Retracts the announcement of any multicast listener from the
 * translation table except the ones listed in the given mcast_list.
 *
 * If mcast_list is NULL then all are retracted.
 */
static void batadv_mcast_mla_tt_retract(struct batadv_priv *bat_priv,
                                        struct hlist_head *mcast_list)
{
        struct batadv_hw_addr *mcast_entry;
        struct hlist_node *tmp;

        hlist_for_each_entry_safe(mcast_entry, tmp, &bat_priv->mcast.mla_list,
                                  list) {
                if (mcast_list &&
                    batadv_mcast_mla_is_duplicate(mcast_entry->addr,
                                                  mcast_list))
                        continue;

                batadv_tt_local_remove(bat_priv, mcast_entry->addr,
                                       BATADV_NO_FLAGS,
                                       "mcast TT outdated", false);

                hlist_del(&mcast_entry->list);
                kfree(mcast_entry);
        }
}

/**
 * batadv_mcast_mla_tt_add() - add multicast listener announcements
 * @bat_priv: the bat priv with all the soft interface information
 * @mcast_list: a list of addresses which are going to get added
 *
 * Adds multicast listener announcements from the given mcast_list to the
 * translation table if they have not been added yet.
 */
static void batadv_mcast_mla_tt_add(struct batadv_priv *bat_priv,
                                    struct hlist_head *mcast_list)
{
        struct batadv_hw_addr *mcast_entry;
        struct hlist_node *tmp;

        if (!mcast_list)
                return;

        hlist_for_each_entry_safe(mcast_entry, tmp, mcast_list, list) {
                if (batadv_mcast_mla_is_duplicate(mcast_entry->addr,
                                                  &bat_priv->mcast.mla_list))
                        continue;

                if (!batadv_tt_local_add(bat_priv->soft_iface,
                                         mcast_entry->addr, BATADV_NO_FLAGS,
                                         BATADV_NULL_IFINDEX, BATADV_NO_MARK))
                        continue;

                hlist_del(&mcast_entry->list);
                hlist_add_head(&mcast_entry->list, &bat_priv->mcast.mla_list);
        }
}

/**
 * batadv_mcast_querier_log() - debug output regarding the querier status on
 *  link
 * @bat_priv: the bat priv with all the soft interface information
 * @str_proto: a string for the querier protocol (e.g. "IGMP" or "MLD")
 * @old_state: the previous querier state on our link
 * @new_state: the new querier state on our link
 *
 * Outputs debug messages to the logging facility with log level 'mcast'
 * regarding changes to the querier status on the link which are relevant
 * to our multicast optimizations.
 *
 * Usually this is about whether a querier appeared or vanished in
 * our mesh or whether the querier is in the suboptimal position of being
 * behind our local bridge segment: Snooping switches will directly
 * forward listener reports to the querier, therefore batman-adv and
 * the bridge will potentially not see these listeners - the querier is
 * potentially shadowing listeners from us then.
 *
 * This is only interesting for nodes with a bridge on top of their
 * soft interface.
 */
static void
batadv_mcast_querier_log(struct batadv_priv *bat_priv, char *str_proto,
                         struct batadv_mcast_querier_state *old_state,
                         struct batadv_mcast_querier_state *new_state)
{
        if (!old_state->exists && new_state->exists)
                batadv_info(bat_priv->soft_iface, "%s Querier appeared\n",
                            str_proto);
        else if (old_state->exists && !new_state->exists)
                batadv_info(bat_priv->soft_iface,
                            "%s Querier disappeared - multicast optimizations disabled\n",
                            str_proto);
        else if (!bat_priv->mcast.mla_flags.bridged && !new_state->exists)
                batadv_info(bat_priv->soft_iface,
                            "No %s Querier present - multicast optimizations disabled\n",
                            str_proto);

        if (new_state->exists) {
                if ((!old_state->shadowing && new_state->shadowing) ||
                    (!old_state->exists && new_state->shadowing))
                        batadv_dbg(BATADV_DBG_MCAST, bat_priv,
                                   "%s Querier is behind our bridged segment: Might shadow listeners\n",
                                   str_proto);
                else if (old_state->shadowing && !new_state->shadowing)
                        batadv_dbg(BATADV_DBG_MCAST, bat_priv,
                                   "%s Querier is not behind our bridged segment\n",
                                   str_proto);
        }
}

/**
 * batadv_mcast_bridge_log() - debug output for topology changes in bridged
 *  setups
 * @bat_priv: the bat priv with all the soft interface information
 * @new_flags: flags indicating the new multicast state
 *
 * If no bridges are ever used on this node, then this function does nothing.
 *
 * Otherwise this function outputs debug information to the 'mcast' log level
 * which might be relevant to our multicast optimizations.
 *
 * More precisely, it outputs information when a bridge interface is added or
 * removed from a soft interface. And when a bridge is present, it further
 * outputs information about the querier state which is relevant for the
 * multicast flags this node is going to set.
 */
static void
batadv_mcast_bridge_log(struct batadv_priv *bat_priv,
                        struct batadv_mcast_mla_flags *new_flags)
{
        struct batadv_mcast_mla_flags *old_flags = &bat_priv->mcast.mla_flags;

        if (!old_flags->bridged && new_flags->bridged)
                batadv_dbg(BATADV_DBG_MCAST, bat_priv,
                           "Bridge added: Setting Unsnoopables(U)-flag\n");
        else if (old_flags->bridged && !new_flags->bridged)
                batadv_dbg(BATADV_DBG_MCAST, bat_priv,
                           "Bridge removed: Unsetting Unsnoopables(U)-flag\n");

        if (new_flags->bridged) {
                batadv_mcast_querier_log(bat_priv, "IGMP",
                                         &old_flags->querier_ipv4,
                                         &new_flags->querier_ipv4);
                batadv_mcast_querier_log(bat_priv, "MLD",
                                         &old_flags->querier_ipv6,
                                         &new_flags->querier_ipv6);
        }
}

/**
 * batadv_mcast_flags_logs() - output debug information about mcast flag changes
 * @bat_priv: the bat priv with all the soft interface information
 * @flags: TVLV flags indicating the new multicast state
 *
 * Whenever the multicast TVLV flags this node announces change, this function
 * should be used to notify userspace about the change.
 */
static void batadv_mcast_flags_log(struct batadv_priv *bat_priv, u8 flags)
{
        bool old_enabled = bat_priv->mcast.mla_flags.enabled;
        u8 old_flags = bat_priv->mcast.mla_flags.tvlv_flags;
        char str_old_flags[] = "[.... . ]";

        sprintf(str_old_flags, "[%c%c%c%s%s]",
                (old_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) ? 'U' : '.',
                (old_flags & BATADV_MCAST_WANT_ALL_IPV4) ? '4' : '.',
                (old_flags & BATADV_MCAST_WANT_ALL_IPV6) ? '6' : '.',
                !(old_flags & BATADV_MCAST_WANT_NO_RTR4) ? "R4" : ". ",
                !(old_flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ");

        batadv_dbg(BATADV_DBG_MCAST, bat_priv,
                   "Changing multicast flags from '%s' to '[%c%c%c%s%s]'\n",
                   old_enabled ? str_old_flags : "<undefined>",
                   (flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) ? 'U' : '.',
                   (flags & BATADV_MCAST_WANT_ALL_IPV4) ? '4' : '.',
                   (flags & BATADV_MCAST_WANT_ALL_IPV6) ? '6' : '.',
                   !(flags & BATADV_MCAST_WANT_NO_RTR4) ? "R4" : ". ",
                   !(flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ");
}

/**
 * batadv_mcast_mla_flags_update() - update multicast flags
 * @bat_priv: the bat priv with all the soft interface information
 * @flags: flags indicating the new multicast state
 *
 * Updates the own multicast tvlv with our current multicast related settings,
 * capabilities and inabilities.
 */
static void
batadv_mcast_mla_flags_update(struct batadv_priv *bat_priv,
                              struct batadv_mcast_mla_flags *flags)
{
        struct batadv_tvlv_mcast_data mcast_data;

        if (!memcmp(flags, &bat_priv->mcast.mla_flags, sizeof(*flags)))
                return;

        batadv_mcast_bridge_log(bat_priv, flags);
        batadv_mcast_flags_log(bat_priv, flags->tvlv_flags);

        mcast_data.flags = flags->tvlv_flags;
        memset(mcast_data.reserved, 0, sizeof(mcast_data.reserved));

        batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 2,
                                       &mcast_data, sizeof(mcast_data));

        bat_priv->mcast.mla_flags = *flags;
}

/**
 * __batadv_mcast_mla_update() - update the own MLAs
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Updates the own multicast listener announcements in the translation
 * table as well as the own, announced multicast tvlv container.
 *
 * Note that non-conflicting reads and writes to bat_priv->mcast.mla_list
 * in batadv_mcast_mla_tt_retract() and batadv_mcast_mla_tt_add() are
 * ensured by the non-parallel execution of the worker this function
 * belongs to.
 */
static void __batadv_mcast_mla_update(struct batadv_priv *bat_priv)
{
        struct net_device *soft_iface = bat_priv->soft_iface;
        struct hlist_head mcast_list = HLIST_HEAD_INIT;
        struct batadv_mcast_mla_flags flags;
        int ret;

        flags = batadv_mcast_mla_flags_get(bat_priv);

        ret = batadv_mcast_mla_softif_get(soft_iface, &mcast_list, &flags);
        if (ret < 0)
                goto out;

        ret = batadv_mcast_mla_bridge_get(soft_iface, &mcast_list, &flags);
        if (ret < 0)
                goto out;

        spin_lock(&bat_priv->mcast.mla_lock);
        batadv_mcast_mla_tt_retract(bat_priv, &mcast_list);
        batadv_mcast_mla_tt_add(bat_priv, &mcast_list);
        batadv_mcast_mla_flags_update(bat_priv, &flags);
        spin_unlock(&bat_priv->mcast.mla_lock);

out:
        batadv_mcast_mla_list_free(&mcast_list);
}

/**
 * batadv_mcast_mla_update() - update the own MLAs
 * @work: kernel work struct
 *
 * Updates the own multicast listener announcements in the translation
 * table as well as the own, announced multicast tvlv container.
 *
 * In the end, reschedules the work timer.
 */
static void batadv_mcast_mla_update(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_priv_mcast *priv_mcast;
        struct batadv_priv *bat_priv;

        delayed_work = to_delayed_work(work);
        priv_mcast = container_of(delayed_work, struct batadv_priv_mcast, work);
        bat_priv = container_of(priv_mcast, struct batadv_priv, mcast);

        __batadv_mcast_mla_update(bat_priv);
        batadv_mcast_start_timer(bat_priv);
}

/**
 * batadv_mcast_is_report_ipv4() - check for IGMP reports
 * @skb: the ethernet frame destined for the mesh
 *
 * This call might reallocate skb data.
 *
 * Checks whether the given frame is a valid IGMP report.
 *
 * Return: If so then true, otherwise false.
 */
static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
{
        if (ip_mc_check_igmp(skb) < 0)
                return false;

        switch (igmp_hdr(skb)->type) {
        case IGMP_HOST_MEMBERSHIP_REPORT:
        case IGMPV2_HOST_MEMBERSHIP_REPORT:
        case IGMPV3_HOST_MEMBERSHIP_REPORT:
                return true;
        }

        return false;
}

/**
 * batadv_mcast_forw_mode_check_ipv4() - check for optimized forwarding
 *  potential
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the IPv4 packet to check
 * @is_unsnoopable: stores whether the destination is snoopable
 * @is_routable: stores whether the destination is routable
 *
 * Checks whether the given IPv4 packet has the potential to be forwarded with a
 * mode more optimal than classic flooding.
 *
 * Return: If so then 0. Otherwise -EINVAL or -ENOMEM in case of memory
 * allocation failure.
 */
static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
                                             struct sk_buff *skb,
                                             bool *is_unsnoopable,
                                             int *is_routable)
{
        struct iphdr *iphdr;

        /* We might fail due to out-of-memory -> drop it */
        if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr)))
                return -ENOMEM;

        if (batadv_mcast_is_report_ipv4(skb))
                return -EINVAL;

        iphdr = ip_hdr(skb);

        /* link-local multicast listeners behind a bridge are
         * not snoopable (see RFC4541, section 2.1.2.2)
         */
        if (ipv4_is_local_multicast(iphdr->daddr))
                *is_unsnoopable = true;
        else
                *is_routable = ETH_P_IP;

        return 0;
}

/**
 * batadv_mcast_is_report_ipv6() - check for MLD reports
 * @skb: the ethernet frame destined for the mesh
 *
 * This call might reallocate skb data.
 *
 * Checks whether the given frame is a valid MLD report.
 *
 * Return: If so then true, otherwise false.
 */
static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
{
        if (ipv6_mc_check_mld(skb) < 0)
                return false;

        switch (icmp6_hdr(skb)->icmp6_type) {
        case ICMPV6_MGM_REPORT:
        case ICMPV6_MLD2_REPORT:
                return true;
        }

        return false;
}

/**
 * batadv_mcast_forw_mode_check_ipv6() - check for optimized forwarding
 *  potential
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the IPv6 packet to check
 * @is_unsnoopable: stores whether the destination is snoopable
 * @is_routable: stores whether the destination is routable
 *
 * Checks whether the given IPv6 packet has the potential to be forwarded with a
 * mode more optimal than classic flooding.
 *
 * Return: If so then 0. Otherwise -EINVAL is or -ENOMEM if we are out of memory
 */
static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
                                             struct sk_buff *skb,
                                             bool *is_unsnoopable,
                                             int *is_routable)
{
        struct ipv6hdr *ip6hdr;

        /* We might fail due to out-of-memory -> drop it */
        if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*ip6hdr)))
                return -ENOMEM;

        if (batadv_mcast_is_report_ipv6(skb))
                return -EINVAL;

        ip6hdr = ipv6_hdr(skb);

        if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) < IPV6_ADDR_SCOPE_LINKLOCAL)
                return -EINVAL;

        /* link-local-all-nodes multicast listeners behind a bridge are
         * not snoopable (see RFC4541, section 3, paragraph 3)
         */
        if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr))
                *is_unsnoopable = true;
        else if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) > IPV6_ADDR_SCOPE_LINKLOCAL)
                *is_routable = ETH_P_IPV6;

        return 0;
}

/**
 * batadv_mcast_forw_mode_check() - check for optimized forwarding potential
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast frame to check
 * @is_unsnoopable: stores whether the destination is snoopable
 * @is_routable: stores whether the destination is routable
 *
 * Checks whether the given multicast ethernet frame has the potential to be
 * forwarded with a mode more optimal than classic flooding.
 *
 * Return: If so then 0. Otherwise -EINVAL is or -ENOMEM if we are out of memory
 */
static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
                                        struct sk_buff *skb,
                                        bool *is_unsnoopable,
                                        int *is_routable)
{
        struct ethhdr *ethhdr = eth_hdr(skb);

        if (!atomic_read(&bat_priv->multicast_mode))
                return -EINVAL;

        switch (ntohs(ethhdr->h_proto)) {
        case ETH_P_IP:
                return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb,
                                                         is_unsnoopable,
                                                         is_routable);
        case ETH_P_IPV6:
                if (!IS_ENABLED(CONFIG_IPV6))
                        return -EINVAL;

                return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
                                                         is_unsnoopable,
                                                         is_routable);
        default:
                return -EINVAL;
        }
}

/**
 * batadv_mcast_forw_want_all_ip_count() - count nodes with unspecific mcast
 *  interest
 * @bat_priv: the bat priv with all the soft interface information
 * @ethhdr: ethernet header of a packet
 *
 * Return: the number of nodes which want all IPv4 multicast traffic if the
 * given ethhdr is from an IPv4 packet or the number of nodes which want all
 * IPv6 traffic if it matches an IPv6 packet.
 */
static int batadv_mcast_forw_want_all_ip_count(struct batadv_priv *bat_priv,
                                               struct ethhdr *ethhdr)
{
        switch (ntohs(ethhdr->h_proto)) {
        case ETH_P_IP:
                return atomic_read(&bat_priv->mcast.num_want_all_ipv4);
        case ETH_P_IPV6:
                return atomic_read(&bat_priv->mcast.num_want_all_ipv6);
        default:
                /* we shouldn't be here... */
                return 0;
        }
}

/**
 * batadv_mcast_forw_rtr_count() - count nodes with a multicast router
 * @bat_priv: the bat priv with all the soft interface information
 * @protocol: the ethernet protocol type to count multicast routers for
 *
 * Return: the number of nodes which want all routable IPv4 multicast traffic
 * if the protocol is ETH_P_IP or the number of nodes which want all routable
 * IPv6 traffic if the protocol is ETH_P_IPV6. Otherwise returns 0.
 */

static int batadv_mcast_forw_rtr_count(struct batadv_priv *bat_priv,
                                       int protocol)
{
        switch (protocol) {
        case ETH_P_IP:
                return atomic_read(&bat_priv->mcast.num_want_all_rtr4);
        case ETH_P_IPV6:
                return atomic_read(&bat_priv->mcast.num_want_all_rtr6);
        default:
                return 0;
        }
}

/**
 * batadv_mcast_forw_tt_node_get() - get a multicast tt node
 * @bat_priv: the bat priv with all the soft interface information
 * @ethhdr: the ether header containing the multicast destination
 *
 * Return: an orig_node matching the multicast address provided by ethhdr
 * via a translation table lookup. This increases the returned nodes refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_tt_node_get(struct batadv_priv *bat_priv,
                              struct ethhdr *ethhdr)
{
        return batadv_transtable_search(bat_priv, NULL, ethhdr->h_dest,
                                        BATADV_NO_FLAGS);
}

/**
 * batadv_mcast_forw_ipv4_node_get() - get a node with an ipv4 flag
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV4 flag set and
 * increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_ipv4_node_get(struct batadv_priv *bat_priv)
{
        struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_orig_node,
                                 &bat_priv->mcast.want_all_ipv4_list,
                                 mcast_want_all_ipv4_node) {
                if (!kref_get_unless_zero(&tmp_orig_node->refcount))
                        continue;

                orig_node = tmp_orig_node;
                break;
        }
        rcu_read_unlock();

        return orig_node;
}

/**
 * batadv_mcast_forw_ipv6_node_get() - get a node with an ipv6 flag
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV6 flag set
 * and increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_ipv6_node_get(struct batadv_priv *bat_priv)
{
        struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_orig_node,
                                 &bat_priv->mcast.want_all_ipv6_list,
                                 mcast_want_all_ipv6_node) {
                if (!kref_get_unless_zero(&tmp_orig_node->refcount))
                        continue;

                orig_node = tmp_orig_node;
                break;
        }
        rcu_read_unlock();

        return orig_node;
}

/**
 * batadv_mcast_forw_ip_node_get() - get a node with an ipv4/ipv6 flag
 * @bat_priv: the bat priv with all the soft interface information
 * @ethhdr: an ethernet header to determine the protocol family from
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV4 or
 * BATADV_MCAST_WANT_ALL_IPV6 flag, depending on the provided ethhdr, sets and
 * increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_ip_node_get(struct batadv_priv *bat_priv,
                              struct ethhdr *ethhdr)
{
        switch (ntohs(ethhdr->h_proto)) {
        case ETH_P_IP:
                return batadv_mcast_forw_ipv4_node_get(bat_priv);
        case ETH_P_IPV6:
                return batadv_mcast_forw_ipv6_node_get(bat_priv);
        default:
                /* we shouldn't be here... */
                return NULL;
        }
}

/**
 * batadv_mcast_forw_unsnoop_node_get() - get a node with an unsnoopable flag
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag
 * set and increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_unsnoop_node_get(struct batadv_priv *bat_priv)
{
        struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_orig_node,
                                 &bat_priv->mcast.want_all_unsnoopables_list,
                                 mcast_want_all_unsnoopables_node) {
                if (!kref_get_unless_zero(&tmp_orig_node->refcount))
                        continue;

                orig_node = tmp_orig_node;
                break;
        }
        rcu_read_unlock();

        return orig_node;
}

/**
 * batadv_mcast_forw_rtr4_node_get() - get a node with an ipv4 mcast router flag
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_NO_RTR4 flag unset and
 * increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_rtr4_node_get(struct batadv_priv *bat_priv)
{
        struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_orig_node,
                                 &bat_priv->mcast.want_all_rtr4_list,
                                 mcast_want_all_rtr4_node) {
                if (!kref_get_unless_zero(&tmp_orig_node->refcount))
                        continue;

                orig_node = tmp_orig_node;
                break;
        }
        rcu_read_unlock();

        return orig_node;
}

/**
 * batadv_mcast_forw_rtr6_node_get() - get a node with an ipv6 mcast router flag
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: an orig_node which has the BATADV_MCAST_WANT_NO_RTR6 flag unset
 * and increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_rtr6_node_get(struct batadv_priv *bat_priv)
{
        struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_orig_node,
                                 &bat_priv->mcast.want_all_rtr6_list,
                                 mcast_want_all_rtr6_node) {
                if (!kref_get_unless_zero(&tmp_orig_node->refcount))
                        continue;

                orig_node = tmp_orig_node;
                break;
        }
        rcu_read_unlock();

        return orig_node;
}

/**
 * batadv_mcast_forw_rtr_node_get() - get a node with an ipv4/ipv6 router flag
 * @bat_priv: the bat priv with all the soft interface information
 * @ethhdr: an ethernet header to determine the protocol family from
 *
 * Return: an orig_node which has no BATADV_MCAST_WANT_NO_RTR4 or
 * BATADV_MCAST_WANT_NO_RTR6 flag, depending on the provided ethhdr, set and
 * increases its refcount.
 */
static struct batadv_orig_node *
batadv_mcast_forw_rtr_node_get(struct batadv_priv *bat_priv,
                               struct ethhdr *ethhdr)
{
        switch (ntohs(ethhdr->h_proto)) {
        case ETH_P_IP:
                return batadv_mcast_forw_rtr4_node_get(bat_priv);
        case ETH_P_IPV6:
                return batadv_mcast_forw_rtr6_node_get(bat_priv);
        default:
                /* we shouldn't be here... */
                return NULL;
        }
}

/**
 * batadv_mcast_forw_mode() - check on how to forward a multicast packet
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: The multicast packet to check
 * @orig: an originator to be set to forward the skb to
 *
 * Return: the forwarding mode as enum batadv_forw_mode and in case of
 * BATADV_FORW_SINGLE set the orig to the single originator the skb
 * should be forwarded to.
 */
enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
                       struct batadv_orig_node **orig)
{
        int ret, tt_count, ip_count, unsnoop_count, total_count;
        bool is_unsnoopable = false;
        unsigned int mcast_fanout;
        struct ethhdr *ethhdr;
        int is_routable = 0;
        int rtr_count = 0;

        ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable,
                                           &is_routable);
        if (ret == -ENOMEM)
                return BATADV_FORW_NONE;
        else if (ret < 0)
                return BATADV_FORW_ALL;

        ethhdr = eth_hdr(skb);

        tt_count = batadv_tt_global_hash_count(bat_priv, ethhdr->h_dest,
                                               BATADV_NO_FLAGS);
        ip_count = batadv_mcast_forw_want_all_ip_count(bat_priv, ethhdr);
        unsnoop_count = !is_unsnoopable ? 0 :
                        atomic_read(&bat_priv->mcast.num_want_all_unsnoopables);
        rtr_count = batadv_mcast_forw_rtr_count(bat_priv, is_routable);

        total_count = tt_count + ip_count + unsnoop_count + rtr_count;

        switch (total_count) {
        case 1:
                if (tt_count)
                        *orig = batadv_mcast_forw_tt_node_get(bat_priv, ethhdr);
                else if (ip_count)
                        *orig = batadv_mcast_forw_ip_node_get(bat_priv, ethhdr);
                else if (unsnoop_count)
                        *orig = batadv_mcast_forw_unsnoop_node_get(bat_priv);
                else if (rtr_count)
                        *orig = batadv_mcast_forw_rtr_node_get(bat_priv,
                                                               ethhdr);

                if (*orig)
                        return BATADV_FORW_SINGLE;

                fallthrough;
        case 0:
                return BATADV_FORW_NONE;
        default:
                mcast_fanout = atomic_read(&bat_priv->multicast_fanout);

                if (!unsnoop_count && total_count <= mcast_fanout)
                        return BATADV_FORW_SOME;
        }

        return BATADV_FORW_ALL;
}

/**
 * batadv_mcast_forw_send_orig() - send a multicast packet to an originator
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to send
 * @vid: the vlan identifier
 * @orig_node: the originator to send the packet to
 *
 * Return: NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
 */
int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
                                struct sk_buff *skb,
                                unsigned short vid,
                                struct batadv_orig_node *orig_node)
{
        /* Avoid sending multicast-in-unicast packets to other BLA
         * gateways - they already got the frame from the LAN side
         * we share with them.
         * TODO: Refactor to take BLA into account earlier, to avoid
         * reducing the mcast_fanout count.
         */
        if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig, vid)) {
                dev_kfree_skb(skb);
                return NET_XMIT_SUCCESS;
        }

        return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
                                       orig_node, vid);
}

/**
 * batadv_mcast_forw_tt() - forwards a packet to multicast listeners
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any multicast
 * listener registered in the translation table. A transmission is performed
 * via a batman-adv unicast packet for each such destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
 * otherwise.
 */
static int
batadv_mcast_forw_tt(struct batadv_priv *bat_priv, struct sk_buff *skb,
                     unsigned short vid)
{
        int ret = NET_XMIT_SUCCESS;
        struct sk_buff *newskb;

        struct batadv_tt_orig_list_entry *orig_entry;

        struct batadv_tt_global_entry *tt_global;
        const u8 *addr = eth_hdr(skb)->h_dest;

        tt_global = batadv_tt_global_hash_find(bat_priv, addr, vid);
        if (!tt_global)
                goto out;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_entry, &tt_global->orig_list, list) {
                newskb = skb_copy(skb, GFP_ATOMIC);
                if (!newskb) {
                        ret = NET_XMIT_DROP;
                        break;
                }

                batadv_mcast_forw_send_orig(bat_priv, newskb, vid,
                                            orig_entry->orig_node);
        }
        rcu_read_unlock();

        batadv_tt_global_entry_put(tt_global);

out:
        return ret;
}

/**
 * batadv_mcast_forw_want_all_ipv4() - forward to nodes with want-all-ipv4
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_ALL_IPV4 flag set. A transmission is performed via a
 * batman-adv unicast packet for each such destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
 * otherwise.
 */
static int
batadv_mcast_forw_want_all_ipv4(struct batadv_priv *bat_priv,
                                struct sk_buff *skb, unsigned short vid)
{
        struct batadv_orig_node *orig_node;
        int ret = NET_XMIT_SUCCESS;
        struct sk_buff *newskb;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_node,
                                 &bat_priv->mcast.want_all_ipv4_list,
                                 mcast_want_all_ipv4_node) {
                newskb = skb_copy(skb, GFP_ATOMIC);
                if (!newskb) {
                        ret = NET_XMIT_DROP;
                        break;
                }

                batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
        }
        rcu_read_unlock();
        return ret;
}

/**
 * batadv_mcast_forw_want_all_ipv6() - forward to nodes with want-all-ipv6
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: The multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_ALL_IPV6 flag set. A transmission is performed via a
 * batman-adv unicast packet for each such destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
 * otherwise.
 */
static int
batadv_mcast_forw_want_all_ipv6(struct batadv_priv *bat_priv,
                                struct sk_buff *skb, unsigned short vid)
{
        struct batadv_orig_node *orig_node;
        int ret = NET_XMIT_SUCCESS;
        struct sk_buff *newskb;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_node,
                                 &bat_priv->mcast.want_all_ipv6_list,
                                 mcast_want_all_ipv6_node) {
                newskb = skb_copy(skb, GFP_ATOMIC);
                if (!newskb) {
                        ret = NET_XMIT_DROP;
                        break;
                }

                batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
        }
        rcu_read_unlock();
        return ret;
}

/**
 * batadv_mcast_forw_want_all() - forward packet to nodes in a want-all list
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_ALL_IPV4 or BATADV_MCAST_WANT_ALL_IPV6 flag set. A
 * transmission is performed via a batman-adv unicast packet for each such
 * destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure or if the protocol family
 * is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
 */
static int
batadv_mcast_forw_want_all(struct batadv_priv *bat_priv,
                           struct sk_buff *skb, unsigned short vid)
{
        switch (ntohs(eth_hdr(skb)->h_proto)) {
        case ETH_P_IP:
                return batadv_mcast_forw_want_all_ipv4(bat_priv, skb, vid);
        case ETH_P_IPV6:
                return batadv_mcast_forw_want_all_ipv6(bat_priv, skb, vid);
        default:
                /* we shouldn't be here... */
                return NET_XMIT_DROP;
        }
}

/**
 * batadv_mcast_forw_want_all_rtr4() - forward to nodes with want-all-rtr4
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_NO_RTR4 flag unset. A transmission is performed via a
 * batman-adv unicast packet for each such destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
 * otherwise.
 */
static int
batadv_mcast_forw_want_all_rtr4(struct batadv_priv *bat_priv,
                                struct sk_buff *skb, unsigned short vid)
{
        struct batadv_orig_node *orig_node;
        int ret = NET_XMIT_SUCCESS;
        struct sk_buff *newskb;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_node,
                                 &bat_priv->mcast.want_all_rtr4_list,
                                 mcast_want_all_rtr4_node) {
                newskb = skb_copy(skb, GFP_ATOMIC);
                if (!newskb) {
                        ret = NET_XMIT_DROP;
                        break;
                }

                batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
        }
        rcu_read_unlock();
        return ret;
}

/**
 * batadv_mcast_forw_want_all_rtr6() - forward to nodes with want-all-rtr6
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: The multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_NO_RTR6 flag unset. A transmission is performed via a
 * batman-adv unicast packet for each such destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
 * otherwise.
 */
static int
batadv_mcast_forw_want_all_rtr6(struct batadv_priv *bat_priv,
                                struct sk_buff *skb, unsigned short vid)
{
        struct batadv_orig_node *orig_node;
        int ret = NET_XMIT_SUCCESS;
        struct sk_buff *newskb;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_node,
                                 &bat_priv->mcast.want_all_rtr6_list,
                                 mcast_want_all_rtr6_node) {
                newskb = skb_copy(skb, GFP_ATOMIC);
                if (!newskb) {
                        ret = NET_XMIT_DROP;
                        break;
                }

                batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
        }
        rcu_read_unlock();
        return ret;
}

/**
 * batadv_mcast_forw_want_rtr() - forward packet to nodes in a want-all-rtr list
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node with a
 * BATADV_MCAST_WANT_NO_RTR4 or BATADV_MCAST_WANT_NO_RTR6 flag unset. A
 * transmission is performed via a batman-adv unicast packet for each such
 * destination node.
 *
 * Return: NET_XMIT_DROP on memory allocation failure or if the protocol family
 * is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
 */
static int
batadv_mcast_forw_want_rtr(struct batadv_priv *bat_priv,
                           struct sk_buff *skb, unsigned short vid)
{
        switch (ntohs(eth_hdr(skb)->h_proto)) {
        case ETH_P_IP:
                return batadv_mcast_forw_want_all_rtr4(bat_priv, skb, vid);
        case ETH_P_IPV6:
                return batadv_mcast_forw_want_all_rtr6(bat_priv, skb, vid);
        default:
                /* we shouldn't be here... */
                return NET_XMIT_DROP;
        }
}

/**
 * batadv_mcast_forw_send() - send packet to any detected multicast recipient
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the multicast packet to transmit
 * @vid: the vlan identifier
 *
 * Sends copies of a frame with multicast destination to any node that signaled
 * interest in it, that is either via the translation table or the according
 * want-all flags. A transmission is performed via a batman-adv unicast packet
 * for each such destination node.
 *
 * The given skb is consumed/freed.
 *
 * Return: NET_XMIT_DROP on memory allocation failure or if the protocol family
 * is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
 */
int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
                           unsigned short vid)
{
        int ret;

        ret = batadv_mcast_forw_tt(bat_priv, skb, vid);
        if (ret != NET_XMIT_SUCCESS) {
                kfree_skb(skb);
                return ret;
        }

        ret = batadv_mcast_forw_want_all(bat_priv, skb, vid);
        if (ret != NET_XMIT_SUCCESS) {
                kfree_skb(skb);
                return ret;
        }

        ret = batadv_mcast_forw_want_rtr(bat_priv, skb, vid);
        if (ret != NET_XMIT_SUCCESS) {
                kfree_skb(skb);
                return ret;
        }

        consume_skb(skb);
        return ret;
}

/**
 * batadv_mcast_want_unsnoop_update() - update unsnoop counter and list
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node which multicast state might have changed of
 * @mcast_flags: flags indicating the new multicast state
 *
 * If the BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag of this originator,
 * orig, has toggled then this method updates the counter and the list
 * accordingly.
 *
 * Caller needs to hold orig->mcast_handler_lock.
 */
static void batadv_mcast_want_unsnoop_update(struct batadv_priv *bat_priv,
                                             struct batadv_orig_node *orig,
                                             u8 mcast_flags)
{
        struct hlist_node *node = &orig->mcast_want_all_unsnoopables_node;
        struct hlist_head *head = &bat_priv->mcast.want_all_unsnoopables_list;

        lockdep_assert_held(&orig->mcast_handler_lock);

        /* switched from flag unset to set */
        if (mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
            !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES)) {
                atomic_inc(&bat_priv->mcast.num_want_all_unsnoopables);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(!hlist_unhashed(node));

                hlist_add_head_rcu(node, head);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        /* switched from flag set to unset */
        } else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) &&
                   orig->mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) {
                atomic_dec(&bat_priv->mcast.num_want_all_unsnoopables);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(hlist_unhashed(node));

                hlist_del_init_rcu(node);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        }
}

/**
 * batadv_mcast_want_ipv4_update() - update want-all-ipv4 counter and list
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node which multicast state might have changed of
 * @mcast_flags: flags indicating the new multicast state
 *
 * If the BATADV_MCAST_WANT_ALL_IPV4 flag of this originator, orig, has
 * toggled then this method updates the counter and the list accordingly.
 *
 * Caller needs to hold orig->mcast_handler_lock.
 */
static void batadv_mcast_want_ipv4_update(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig,
                                          u8 mcast_flags)
{
        struct hlist_node *node = &orig->mcast_want_all_ipv4_node;
        struct hlist_head *head = &bat_priv->mcast.want_all_ipv4_list;

        lockdep_assert_held(&orig->mcast_handler_lock);

        /* switched from flag unset to set */
        if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV4 &&
            !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_IPV4)) {
                atomic_inc(&bat_priv->mcast.num_want_all_ipv4);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(!hlist_unhashed(node));

                hlist_add_head_rcu(node, head);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        /* switched from flag set to unset */
        } else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_IPV4) &&
                   orig->mcast_flags & BATADV_MCAST_WANT_ALL_IPV4) {
                atomic_dec(&bat_priv->mcast.num_want_all_ipv4);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(hlist_unhashed(node));

                hlist_del_init_rcu(node);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        }
}

/**
 * batadv_mcast_want_ipv6_update() - update want-all-ipv6 counter and list
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node which multicast state might have changed of
 * @mcast_flags: flags indicating the new multicast state
 *
 * If the BATADV_MCAST_WANT_ALL_IPV6 flag of this originator, orig, has
 * toggled then this method updates the counter and the list accordingly.
 *
 * Caller needs to hold orig->mcast_handler_lock.
 */
static void batadv_mcast_want_ipv6_update(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig,
                                          u8 mcast_flags)
{
        struct hlist_node *node = &orig->mcast_want_all_ipv6_node;
        struct hlist_head *head = &bat_priv->mcast.want_all_ipv6_list;

        lockdep_assert_held(&orig->mcast_handler_lock);

        /* switched from flag unset to set */
        if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV6 &&
            !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_IPV6)) {
                atomic_inc(&bat_priv->mcast.num_want_all_ipv6);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(!hlist_unhashed(node));

                hlist_add_head_rcu(node, head);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        /* switched from flag set to unset */
        } else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_IPV6) &&
                   orig->mcast_flags & BATADV_MCAST_WANT_ALL_IPV6) {
                atomic_dec(&bat_priv->mcast.num_want_all_ipv6);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(hlist_unhashed(node));

                hlist_del_init_rcu(node);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        }
}

/**
 * batadv_mcast_want_rtr4_update() - update want-all-rtr4 counter and list
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node which multicast state might have changed of
 * @mcast_flags: flags indicating the new multicast state
 *
 * If the BATADV_MCAST_WANT_NO_RTR4 flag of this originator, orig, has
 * toggled then this method updates the counter and the list accordingly.
 *
 * Caller needs to hold orig->mcast_handler_lock.
 */
static void batadv_mcast_want_rtr4_update(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig,
                                          u8 mcast_flags)
{
        struct hlist_node *node = &orig->mcast_want_all_rtr4_node;
        struct hlist_head *head = &bat_priv->mcast.want_all_rtr4_list;

        lockdep_assert_held(&orig->mcast_handler_lock);

        /* switched from flag set to unset */
        if (!(mcast_flags & BATADV_MCAST_WANT_NO_RTR4) &&
            orig->mcast_flags & BATADV_MCAST_WANT_NO_RTR4) {
                atomic_inc(&bat_priv->mcast.num_want_all_rtr4);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(!hlist_unhashed(node));

                hlist_add_head_rcu(node, head);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        /* switched from flag unset to set */
        } else if (mcast_flags & BATADV_MCAST_WANT_NO_RTR4 &&
                   !(orig->mcast_flags & BATADV_MCAST_WANT_NO_RTR4)) {
                atomic_dec(&bat_priv->mcast.num_want_all_rtr4);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(hlist_unhashed(node));

                hlist_del_init_rcu(node);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        }
}

/**
 * batadv_mcast_want_rtr6_update() - update want-all-rtr6 counter and list
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node which multicast state might have changed of
 * @mcast_flags: flags indicating the new multicast state
 *
 * If the BATADV_MCAST_WANT_NO_RTR6 flag of this originator, orig, has
 * toggled then this method updates the counter and the list accordingly.
 *
 * Caller needs to hold orig->mcast_handler_lock.
 */
static void batadv_mcast_want_rtr6_update(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig,
                                          u8 mcast_flags)
{
        struct hlist_node *node = &orig->mcast_want_all_rtr6_node;
        struct hlist_head *head = &bat_priv->mcast.want_all_rtr6_list;

        lockdep_assert_held(&orig->mcast_handler_lock);

        /* switched from flag set to unset */
        if (!(mcast_flags & BATADV_MCAST_WANT_NO_RTR6) &&
            orig->mcast_flags & BATADV_MCAST_WANT_NO_RTR6) {
                atomic_inc(&bat_priv->mcast.num_want_all_rtr6);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(!hlist_unhashed(node));

                hlist_add_head_rcu(node, head);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        /* switched from flag unset to set */
        } else if (mcast_flags & BATADV_MCAST_WANT_NO_RTR6 &&
                   !(orig->mcast_flags & BATADV_MCAST_WANT_NO_RTR6)) {
                atomic_dec(&bat_priv->mcast.num_want_all_rtr6);

                spin_lock_bh(&bat_priv->mcast.want_lists_lock);
                /* flag checks above + mcast_handler_lock prevents this */
                WARN_ON(hlist_unhashed(node));

                hlist_del_init_rcu(node);
                spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
        }
}

/**
 * batadv_mcast_tvlv_flags_get() - get multicast flags from an OGM TVLV
 * @enabled: whether the originator has multicast TVLV support enabled
 * @tvlv_value: tvlv buffer containing the multicast flags
 * @tvlv_value_len: tvlv buffer length
 *
 * Return: multicast flags for the given tvlv buffer
 */
static u8
batadv_mcast_tvlv_flags_get(bool enabled, void *tvlv_value, u16 tvlv_value_len)
{
        u8 mcast_flags = BATADV_NO_FLAGS;

        if (enabled && tvlv_value && tvlv_value_len >= sizeof(mcast_flags))
                mcast_flags = *(u8 *)tvlv_value;

        if (!enabled) {
                mcast_flags |= BATADV_MCAST_WANT_ALL_IPV4;
                mcast_flags |= BATADV_MCAST_WANT_ALL_IPV6;
        }

        /* remove redundant flags to avoid sending duplicate packets later */
        if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV4)
                mcast_flags |= BATADV_MCAST_WANT_NO_RTR4;

        if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV6)
                mcast_flags |= BATADV_MCAST_WANT_NO_RTR6;

        return mcast_flags;
}

/**
 * batadv_mcast_tvlv_ogm_handler() - process incoming multicast tvlv container
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the orig_node of the ogm
 * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
 * @tvlv_value: tvlv buffer containing the multicast data
 * @tvlv_value_len: tvlv buffer length
 */
static void batadv_mcast_tvlv_ogm_handler(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig,
                                          u8 flags,
                                          void *tvlv_value,
                                          u16 tvlv_value_len)
{
        bool orig_mcast_enabled = !(flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
        u8 mcast_flags;

        mcast_flags = batadv_mcast_tvlv_flags_get(orig_mcast_enabled,
                                                  tvlv_value, tvlv_value_len);

        spin_lock_bh(&orig->mcast_handler_lock);

        if (orig_mcast_enabled &&
            !test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities)) {
                set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
        } else if (!orig_mcast_enabled &&
                   test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities)) {
                clear_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
        }

        set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized);

        batadv_mcast_want_unsnoop_update(bat_priv, orig, mcast_flags);
        batadv_mcast_want_ipv4_update(bat_priv, orig, mcast_flags);
        batadv_mcast_want_ipv6_update(bat_priv, orig, mcast_flags);
        batadv_mcast_want_rtr4_update(bat_priv, orig, mcast_flags);
        batadv_mcast_want_rtr6_update(bat_priv, orig, mcast_flags);

        orig->mcast_flags = mcast_flags;
        spin_unlock_bh(&orig->mcast_handler_lock);
}

/**
 * batadv_mcast_init() - initialize the multicast optimizations structures
 * @bat_priv: the bat priv with all the soft interface information
 */
void batadv_mcast_init(struct batadv_priv *bat_priv)
{
        batadv_tvlv_handler_register(bat_priv, batadv_mcast_tvlv_ogm_handler,
                                     NULL, BATADV_TVLV_MCAST, 2,
                                     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);

        INIT_DELAYED_WORK(&bat_priv->mcast.work, batadv_mcast_mla_update);
        batadv_mcast_start_timer(bat_priv);
}

/**
 * batadv_mcast_mesh_info_put() - put multicast info into a netlink message
 * @msg: buffer for the message
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: 0 or error code.
 */
int batadv_mcast_mesh_info_put(struct sk_buff *msg,
                               struct batadv_priv *bat_priv)
{
        u32 flags = bat_priv->mcast.mla_flags.tvlv_flags;
        u32 flags_priv = BATADV_NO_FLAGS;

        if (bat_priv->mcast.mla_flags.bridged) {
                flags_priv |= BATADV_MCAST_FLAGS_BRIDGED;

                if (bat_priv->mcast.mla_flags.querier_ipv4.exists)
                        flags_priv |= BATADV_MCAST_FLAGS_QUERIER_IPV4_EXISTS;
                if (bat_priv->mcast.mla_flags.querier_ipv6.exists)
                        flags_priv |= BATADV_MCAST_FLAGS_QUERIER_IPV6_EXISTS;
                if (bat_priv->mcast.mla_flags.querier_ipv4.shadowing)
                        flags_priv |= BATADV_MCAST_FLAGS_QUERIER_IPV4_SHADOWING;
                if (bat_priv->mcast.mla_flags.querier_ipv6.shadowing)
                        flags_priv |= BATADV_MCAST_FLAGS_QUERIER_IPV6_SHADOWING;
        }

        if (nla_put_u32(msg, BATADV_ATTR_MCAST_FLAGS, flags) ||
            nla_put_u32(msg, BATADV_ATTR_MCAST_FLAGS_PRIV, flags_priv))
                return -EMSGSIZE;

        return 0;
}

/**
 * batadv_mcast_flags_dump_entry() - dump one entry of the multicast flags table
 *  to a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @orig_node: originator to dump the multicast flags of
 *
 * Return: 0 or error code.
 */
static int
batadv_mcast_flags_dump_entry(struct sk_buff *msg, u32 portid,
                              struct netlink_callback *cb,
                              struct batadv_orig_node *orig_node)
{
        void *hdr;

        hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
                          &batadv_netlink_family, NLM_F_MULTI,
                          BATADV_CMD_GET_MCAST_FLAGS);
        if (!hdr)
                return -ENOBUFS;

        genl_dump_check_consistent(cb, hdr);

        if (nla_put(msg, BATADV_ATTR_ORIG_ADDRESS, ETH_ALEN,
                    orig_node->orig)) {
                genlmsg_cancel(msg, hdr);
                return -EMSGSIZE;
        }

        if (test_bit(BATADV_ORIG_CAPA_HAS_MCAST,
                     &orig_node->capabilities)) {
                if (nla_put_u32(msg, BATADV_ATTR_MCAST_FLAGS,
                                orig_node->mcast_flags)) {
                        genlmsg_cancel(msg, hdr);
                        return -EMSGSIZE;
                }
        }

        genlmsg_end(msg, hdr);
        return 0;
}

/**
 * batadv_mcast_flags_dump_bucket() - dump one bucket of the multicast flags
 *  table to a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @hash: hash to dump
 * @bucket: bucket index to dump
 * @idx_skip: How many entries to skip
 *
 * Return: 0 or error code.
 */
static int
batadv_mcast_flags_dump_bucket(struct sk_buff *msg, u32 portid,
                               struct netlink_callback *cb,
                               struct batadv_hashtable *hash,
                               unsigned int bucket, long *idx_skip)
{
        struct batadv_orig_node *orig_node;
        long idx = 0;

        spin_lock_bh(&hash->list_locks[bucket]);
        cb->seq = atomic_read(&hash->generation) << 1 | 1;

        hlist_for_each_entry(orig_node, &hash->table[bucket], hash_entry) {
                if (!test_bit(BATADV_ORIG_CAPA_HAS_MCAST,
                              &orig_node->capa_initialized))
                        continue;

                if (idx < *idx_skip)
                        goto skip;

                if (batadv_mcast_flags_dump_entry(msg, portid, cb, orig_node)) {
                        spin_unlock_bh(&hash->list_locks[bucket]);
                        *idx_skip = idx;

                        return -EMSGSIZE;
                }

skip:
                idx++;
        }
        spin_unlock_bh(&hash->list_locks[bucket]);

        return 0;
}

/**
 * __batadv_mcast_flags_dump() - dump multicast flags table to a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @bat_priv: the bat priv with all the soft interface information
 * @bucket: current bucket to dump
 * @idx: index in current bucket to the next entry to dump
 *
 * Return: 0 or error code.
 */
static int
__batadv_mcast_flags_dump(struct sk_buff *msg, u32 portid,
                          struct netlink_callback *cb,
                          struct batadv_priv *bat_priv, long *bucket, long *idx)
{
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        long bucket_tmp = *bucket;
        long idx_tmp = *idx;

        while (bucket_tmp < hash->size) {
                if (batadv_mcast_flags_dump_bucket(msg, portid, cb, hash,
                                                   bucket_tmp, &idx_tmp))
                        break;

                bucket_tmp++;
                idx_tmp = 0;
        }

        *bucket = bucket_tmp;
        *idx = idx_tmp;

        return msg->len;
}

/**
 * batadv_mcast_netlink_get_primary() - get primary interface from netlink
 *  callback
 * @cb: netlink callback structure
 * @primary_if: the primary interface pointer to return the result in
 *
 * Return: 0 or error code.
 */
static int
batadv_mcast_netlink_get_primary(struct netlink_callback *cb,
                                 struct batadv_hard_iface **primary_if)
{
        struct batadv_hard_iface *hard_iface = NULL;
        struct net *net = sock_net(cb->skb->sk);
        struct net_device *soft_iface;
        struct batadv_priv *bat_priv;
        int ifindex;
        int ret = 0;

        ifindex = batadv_netlink_get_ifindex(cb->nlh, BATADV_ATTR_MESH_IFINDEX);
        if (!ifindex)
                return -EINVAL;

        soft_iface = dev_get_by_index(net, ifindex);
        if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
                ret = -ENODEV;
                goto out;
        }

        bat_priv = netdev_priv(soft_iface);

        hard_iface = batadv_primary_if_get_selected(bat_priv);
        if (!hard_iface || hard_iface->if_status != BATADV_IF_ACTIVE) {
                ret = -ENOENT;
                goto out;
        }

out:
        if (soft_iface)
                dev_put(soft_iface);

        if (!ret && primary_if)
                *primary_if = hard_iface;
        else if (hard_iface)
                batadv_hardif_put(hard_iface);

        return ret;
}

/**
 * batadv_mcast_flags_dump() - dump multicast flags table to a netlink socket
 * @msg: buffer for the message
 * @cb: callback structure containing arguments
 *
 * Return: message length.
 */
int batadv_mcast_flags_dump(struct sk_buff *msg, struct netlink_callback *cb)
{
        struct batadv_hard_iface *primary_if = NULL;
        int portid = NETLINK_CB(cb->skb).portid;
        struct batadv_priv *bat_priv;
        long *bucket = &cb->args[0];
        long *idx = &cb->args[1];
        int ret;

        ret = batadv_mcast_netlink_get_primary(cb, &primary_if);
        if (ret)
                return ret;

        bat_priv = netdev_priv(primary_if->soft_iface);
        ret = __batadv_mcast_flags_dump(msg, portid, cb, bat_priv, bucket, idx);

        batadv_hardif_put(primary_if);
        return ret;
}

/**
 * batadv_mcast_free() - free the multicast optimizations structures
 * @bat_priv: the bat priv with all the soft interface information
 */
void batadv_mcast_free(struct batadv_priv *bat_priv)
{
        cancel_delayed_work_sync(&bat_priv->mcast.work);

        batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 2);
        batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 2);

        /* safely calling outside of worker, as worker was canceled above */
        batadv_mcast_mla_tt_retract(bat_priv, NULL);
}

/**
 * batadv_mcast_purge_orig() - reset originator global mcast state modifications
 * @orig: the originator which is going to get purged
 */
void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
{
        struct batadv_priv *bat_priv = orig->bat_priv;

        spin_lock_bh(&orig->mcast_handler_lock);

        batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);
        batadv_mcast_want_ipv4_update(bat_priv, orig, BATADV_NO_FLAGS);
        batadv_mcast_want_ipv6_update(bat_priv, orig, BATADV_NO_FLAGS);
        batadv_mcast_want_rtr4_update(bat_priv, orig,
                                      BATADV_MCAST_WANT_NO_RTR4);
        batadv_mcast_want_rtr6_update(bat_priv, orig,
                                      BATADV_MCAST_WANT_NO_RTR6);

        spin_unlock_bh(&orig->mcast_handler_lock);
}