Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1113 insertions, 0 deletions

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
new file mode 100644
index 000000000..6d68cdb9d
--- /dev/null
+++ b/net/batman-adv/hard-interface.c
@@ -0,0 +1,1113 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2007-2018  B.A.T.M.A.N. contributors:
+ *
+ * Marek Lindner, Simon Wunderlich
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hard-interface.h"
+#include "main.h"
+
+#include <linux/atomic.h>
+#include <linux/byteorder/generic.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/if.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <linux/printk.h>
+#include <linux/rculist.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <net/net_namespace.h>
+#include <net/rtnetlink.h>
+#include <uapi/linux/batadv_packet.h>
+
+#include "bat_v.h"
+#include "bridge_loop_avoidance.h"
+#include "debugfs.h"
+#include "distributed-arp-table.h"
+#include "gateway_client.h"
+#include "log.h"
+#include "originator.h"
+#include "send.h"
+#include "soft-interface.h"
+#include "sysfs.h"
+#include "translation-table.h"
+
+/**
+ * batadv_hardif_release() - release hard interface from lists and queue for
+ *  free after rcu grace period
+ * @ref: kref pointer of the hard interface
+ */
+void batadv_hardif_release(struct kref *ref)
+{
+	struct batadv_hard_iface *hard_iface;
+
+	hard_iface = container_of(ref, struct batadv_hard_iface, refcount);
+	dev_put(hard_iface->net_dev);
+
+	kfree_rcu(hard_iface, rcu);
+}
+
+/**
+ * batadv_hardif_get_by_netdev() - Get hard interface object of a net_device
+ * @net_dev: net_device to search for
+ *
+ * Return: batadv_hard_iface of net_dev (with increased refcnt), NULL on errors
+ */
+struct batadv_hard_iface *
+batadv_hardif_get_by_netdev(const struct net_device *net_dev)
+{
+	struct batadv_hard_iface *hard_iface;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->net_dev == net_dev &&
+		    kref_get_unless_zero(&hard_iface->refcount))
+			goto out;
+	}
+
+	hard_iface = NULL;
+
+out:
+	rcu_read_unlock();
+	return hard_iface;
+}
+
+/**
+ * batadv_getlink_net() - return link net namespace (of use fallback)
+ * @netdev: net_device to check
+ * @fallback_net: return in case get_link_net is not available for @netdev
+ *
+ * Return: result of rtnl_link_ops->get_link_net or @fallback_net
+ */
+static struct net *batadv_getlink_net(const struct net_device *netdev,
+				      struct net *fallback_net)
+{
+	if (!netdev->rtnl_link_ops)
+		return fallback_net;
+
+	if (!netdev->rtnl_link_ops->get_link_net)
+		return fallback_net;
+
+	return netdev->rtnl_link_ops->get_link_net(netdev);
+}
+
+/**
+ * batadv_mutual_parents() - check if two devices are each others parent
+ * @dev1: 1st net dev
+ * @net1: 1st devices netns
+ * @dev2: 2nd net dev
+ * @net2: 2nd devices netns
+ *
+ * veth devices come in pairs and each is the parent of the other!
+ *
+ * Return: true if the devices are each others parent, otherwise false
+ */
+static bool batadv_mutual_parents(const struct net_device *dev1,
+				  struct net *net1,
+				  const struct net_device *dev2,
+				  struct net *net2)
+{
+	int dev1_parent_iflink = dev_get_iflink(dev1);
+	int dev2_parent_iflink = dev_get_iflink(dev2);
+	const struct net *dev1_parent_net;
+	const struct net *dev2_parent_net;
+
+	dev1_parent_net = batadv_getlink_net(dev1, net1);
+	dev2_parent_net = batadv_getlink_net(dev2, net2);
+
+	if (!dev1_parent_iflink || !dev2_parent_iflink)
+		return false;
+
+	return (dev1_parent_iflink == dev2->ifindex) &&
+	       (dev2_parent_iflink == dev1->ifindex) &&
+	       net_eq(dev1_parent_net, net2) &&
+	       net_eq(dev2_parent_net, net1);
+}
+
+/**
+ * batadv_is_on_batman_iface() - check if a device is a batman iface descendant
+ * @net_dev: the device to check
+ *
+ * If the user creates any virtual device on top of a batman-adv interface, it
+ * is important to prevent this new interface to be used to create a new mesh
+ * network (this behaviour would lead to a batman-over-batman configuration).
+ * This function recursively checks all the fathers of the device passed as
+ * argument looking for a batman-adv soft interface.
+ *
+ * Return: true if the device is descendant of a batman-adv mesh interface (or
+ * if it is a batman-adv interface itself), false otherwise
+ */
+static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
+{
+	struct net *net = dev_net(net_dev);
+	struct net_device *parent_dev;
+	struct net *parent_net;
+	int iflink;
+	bool ret;
+
+	/* check if this is a batman-adv mesh interface */
+	if (batadv_softif_is_valid(net_dev))
+		return true;
+
+	iflink = dev_get_iflink(net_dev);
+	if (iflink == 0)
+		return false;
+
+	parent_net = batadv_getlink_net(net_dev, net);
+
+	/* iflink to itself, most likely physical device */
+	if (net == parent_net && iflink == net_dev->ifindex)
+		return false;
+
+	/* recurse over the parent device */
+	parent_dev = __dev_get_by_index((struct net *)parent_net, iflink);
+	/* if we got a NULL parent_dev there is something broken.. */
+	if (!parent_dev) {
+		pr_err("Cannot find parent device\n");
+		return false;
+	}
+
+	if (batadv_mutual_parents(net_dev, net, parent_dev, parent_net))
+		return false;
+
+	ret = batadv_is_on_batman_iface(parent_dev);
+
+	return ret;
+}
+
+static bool batadv_is_valid_iface(const struct net_device *net_dev)
+{
+	if (net_dev->flags & IFF_LOOPBACK)
+		return false;
+
+	if (net_dev->type != ARPHRD_ETHER)
+		return false;
+
+	if (net_dev->addr_len != ETH_ALEN)
+		return false;
+
+	/* no batman over batman */
+	if (batadv_is_on_batman_iface(net_dev))
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_get_real_netdevice() - check if the given netdev struct is a virtual
+ *  interface on top of another 'real' interface
+ * @netdev: the device to check
+ *
+ * Callers must hold the rtnl semaphore. You may want batadv_get_real_netdev()
+ * instead of this.
+ *
+ * Return: the 'real' net device or the original net device and NULL in case
+ *  of an error.
+ */
+static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
+{
+	struct batadv_hard_iface *hard_iface = NULL;
+	struct net_device *real_netdev = NULL;
+	struct net *real_net;
+	struct net *net;
+	int iflink;
+
+	ASSERT_RTNL();
+
+	if (!netdev)
+		return NULL;
+
+	iflink = dev_get_iflink(netdev);
+	if (iflink == 0) {
+		dev_hold(netdev);
+		return netdev;
+	}
+
+	hard_iface = batadv_hardif_get_by_netdev(netdev);
+	if (!hard_iface || !hard_iface->soft_iface)
+		goto out;
+
+	net = dev_net(hard_iface->soft_iface);
+	real_net = batadv_getlink_net(netdev, net);
+
+	/* iflink to itself, most likely physical device */
+	if (net == real_net && netdev->ifindex == iflink) {
+		real_netdev = netdev;
+		dev_hold(real_netdev);
+		goto out;
+	}
+
+	real_netdev = dev_get_by_index(real_net, iflink);
+
+out:
+	if (hard_iface)
+		batadv_hardif_put(hard_iface);
+	return real_netdev;
+}
+
+/**
+ * batadv_get_real_netdev() - check if the given net_device struct is a virtual
+ *  interface on top of another 'real' interface
+ * @net_device: the device to check
+ *
+ * Return: the 'real' net device or the original net device and NULL in case
+ *  of an error.
+ */
+struct net_device *batadv_get_real_netdev(struct net_device *net_device)
+{
+	struct net_device *real_netdev;
+
+	rtnl_lock();
+	real_netdev = batadv_get_real_netdevice(net_device);
+	rtnl_unlock();
+
+	return real_netdev;
+}
+
+/**
+ * batadv_is_wext_netdev() - check if the given net_device struct is a
+ *  wext wifi interface
+ * @net_device: the device to check
+ *
+ * Return: true if the net device is a wext wireless device, false
+ *  otherwise.
+ */
+static bool batadv_is_wext_netdev(struct net_device *net_device)
+{
+	if (!net_device)
+		return false;
+
+#ifdef CONFIG_WIRELESS_EXT
+	/* pre-cfg80211 drivers have to implement WEXT, so it is possible to
+	 * check for wireless_handlers != NULL
+	 */
+	if (net_device->wireless_handlers)
+		return true;
+#endif
+
+	return false;
+}
+
+/**
+ * batadv_is_cfg80211_netdev() - check if the given net_device struct is a
+ *  cfg80211 wifi interface
+ * @net_device: the device to check
+ *
+ * Return: true if the net device is a cfg80211 wireless device, false
+ *  otherwise.
+ */
+static bool batadv_is_cfg80211_netdev(struct net_device *net_device)
+{
+	if (!net_device)
+		return false;
+
+	/* cfg80211 drivers have to set ieee80211_ptr */
+	if (net_device->ieee80211_ptr)
+		return true;
+
+	return false;
+}
+
+/**
+ * batadv_wifi_flags_evaluate() - calculate wifi flags for net_device
+ * @net_device: the device to check
+ *
+ * Return: batadv_hard_iface_wifi_flags flags of the device
+ */
+static u32 batadv_wifi_flags_evaluate(struct net_device *net_device)
+{
+	u32 wifi_flags = 0;
+	struct net_device *real_netdev;
+
+	if (batadv_is_wext_netdev(net_device))
+		wifi_flags |= BATADV_HARDIF_WIFI_WEXT_DIRECT;
+
+	if (batadv_is_cfg80211_netdev(net_device))
+		wifi_flags |= BATADV_HARDIF_WIFI_CFG80211_DIRECT;
+
+	real_netdev = batadv_get_real_netdevice(net_device);
+	if (!real_netdev)
+		return wifi_flags;
+
+	if (real_netdev == net_device)
+		goto out;
+
+	if (batadv_is_wext_netdev(real_netdev))
+		wifi_flags |= BATADV_HARDIF_WIFI_WEXT_INDIRECT;
+
+	if (batadv_is_cfg80211_netdev(real_netdev))
+		wifi_flags |= BATADV_HARDIF_WIFI_CFG80211_INDIRECT;
+
+out:
+	dev_put(real_netdev);
+	return wifi_flags;
+}
+
+/**
+ * batadv_is_cfg80211_hardif() - check if the given hardif is a cfg80211 wifi
+ *  interface
+ * @hard_iface: the device to check
+ *
+ * Return: true if the net device is a cfg80211 wireless device, false
+ *  otherwise.
+ */
+bool batadv_is_cfg80211_hardif(struct batadv_hard_iface *hard_iface)
+{
+	u32 allowed_flags = 0;
+
+	allowed_flags |= BATADV_HARDIF_WIFI_CFG80211_DIRECT;
+	allowed_flags |= BATADV_HARDIF_WIFI_CFG80211_INDIRECT;
+
+	return !!(hard_iface->wifi_flags & allowed_flags);
+}
+
+/**
+ * batadv_is_wifi_hardif() - check if the given hardif is a wifi interface
+ * @hard_iface: the device to check
+ *
+ * Return: true if the net device is a 802.11 wireless device, false otherwise.
+ */
+bool batadv_is_wifi_hardif(struct batadv_hard_iface *hard_iface)
+{
+	if (!hard_iface)
+		return false;
+
+	return hard_iface->wifi_flags != 0;
+}
+
+/**
+ * batadv_hardif_no_broadcast() - check whether (re)broadcast is necessary
+ * @if_outgoing: the outgoing interface checked and considered for (re)broadcast
+ * @orig_addr: the originator of this packet
+ * @orig_neigh: originator address of the forwarder we just got the packet from
+ *  (NULL if we originated)
+ *
+ * Checks whether a packet needs to be (re)broadcasted on the given interface.
+ *
+ * Return:
+ *	BATADV_HARDIF_BCAST_NORECIPIENT: No neighbor on interface
+ *	BATADV_HARDIF_BCAST_DUPFWD: Just one neighbor, but it is the forwarder
+ *	BATADV_HARDIF_BCAST_DUPORIG: Just one neighbor, but it is the originator
+ *	BATADV_HARDIF_BCAST_OK: Several neighbors, must broadcast
+ */
+int batadv_hardif_no_broadcast(struct batadv_hard_iface *if_outgoing,
+			       u8 *orig_addr, u8 *orig_neigh)
+{
+	struct batadv_hardif_neigh_node *hardif_neigh;
+	struct hlist_node *first;
+	int ret = BATADV_HARDIF_BCAST_OK;
+
+	rcu_read_lock();
+
+	/* 0 neighbors -> no (re)broadcast */
+	first = rcu_dereference(hlist_first_rcu(&if_outgoing->neigh_list));
+	if (!first) {
+		ret = BATADV_HARDIF_BCAST_NORECIPIENT;
+		goto out;
+	}
+
+	/* >1 neighbors -> (re)brodcast */
+	if (rcu_dereference(hlist_next_rcu(first)))
+		goto out;
+
+	hardif_neigh = hlist_entry(first, struct batadv_hardif_neigh_node,
+				   list);
+
+	/* 1 neighbor, is the originator -> no rebroadcast */
+	if (orig_addr && batadv_compare_eth(hardif_neigh->orig, orig_addr)) {
+		ret = BATADV_HARDIF_BCAST_DUPORIG;
+	/* 1 neighbor, is the one we received from -> no rebroadcast */
+	} else if (orig_neigh &&
+		   batadv_compare_eth(hardif_neigh->orig, orig_neigh)) {
+		ret = BATADV_HARDIF_BCAST_DUPFWD;
+	}
+
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+static struct batadv_hard_iface *
+batadv_hardif_get_active(const struct net_device *soft_iface)
+{
+	struct batadv_hard_iface *hard_iface;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->soft_iface != soft_iface)
+			continue;
+
+		if (hard_iface->if_status == BATADV_IF_ACTIVE &&
+		    kref_get_unless_zero(&hard_iface->refcount))
+			goto out;
+	}
+
+	hard_iface = NULL;
+
+out:
+	rcu_read_unlock();
+	return hard_iface;
+}
+
+static void batadv_primary_if_update_addr(struct batadv_priv *bat_priv,
+					  struct batadv_hard_iface *oldif)
+{
+	struct batadv_hard_iface *primary_if;
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		goto out;
+
+	batadv_dat_init_own_addr(bat_priv, primary_if);
+	batadv_bla_update_orig_address(bat_priv, primary_if, oldif);
+out:
+	if (primary_if)
+		batadv_hardif_put(primary_if);
+}
+
+static void batadv_primary_if_select(struct batadv_priv *bat_priv,
+				     struct batadv_hard_iface *new_hard_iface)
+{
+	struct batadv_hard_iface *curr_hard_iface;
+
+	ASSERT_RTNL();
+
+	if (new_hard_iface)
+		kref_get(&new_hard_iface->refcount);
+
+	curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
+	rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);
+
+	if (!new_hard_iface)
+		goto out;
+
+	bat_priv->algo_ops->iface.primary_set(new_hard_iface);
+	batadv_primary_if_update_addr(bat_priv, curr_hard_iface);
+
+out:
+	if (curr_hard_iface)
+		batadv_hardif_put(curr_hard_iface);
+}
+
+static bool
+batadv_hardif_is_iface_up(const struct batadv_hard_iface *hard_iface)
+{
+	if (hard_iface->net_dev->flags & IFF_UP)
+		return true;
+
+	return false;
+}
+
+static void batadv_check_known_mac_addr(const struct net_device *net_dev)
+{
+	const struct batadv_hard_iface *hard_iface;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->if_status != BATADV_IF_ACTIVE &&
+		    hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
+			continue;
+
+		if (hard_iface->net_dev == net_dev)
+			continue;
+
+		if (!batadv_compare_eth(hard_iface->net_dev->dev_addr,
+					net_dev->dev_addr))
+			continue;
+
+		pr_warn("The newly added mac address (%pM) already exists on: %s\n",
+			net_dev->dev_addr, hard_iface->net_dev->name);
+		pr_warn("It is strongly recommended to keep mac addresses unique to avoid problems!\n");
+	}
+	rcu_read_unlock();
+}
+
+/**
+ * batadv_hardif_recalc_extra_skbroom() - Recalculate skbuff extra head/tailroom
+ * @soft_iface: netdev struct of the mesh interface
+ */
+static void batadv_hardif_recalc_extra_skbroom(struct net_device *soft_iface)
+{
+	const struct batadv_hard_iface *hard_iface;
+	unsigned short lower_header_len = ETH_HLEN;
+	unsigned short lower_headroom = 0;
+	unsigned short lower_tailroom = 0;
+	unsigned short needed_headroom;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
+			continue;
+
+		if (hard_iface->soft_iface != soft_iface)
+			continue;
+
+		lower_header_len = max_t(unsigned short, lower_header_len,
+					 hard_iface->net_dev->hard_header_len);
+
+		lower_headroom = max_t(unsigned short, lower_headroom,
+				       hard_iface->net_dev->needed_headroom);
+
+		lower_tailroom = max_t(unsigned short, lower_tailroom,
+				       hard_iface->net_dev->needed_tailroom);
+	}
+	rcu_read_unlock();
+
+	needed_headroom = lower_headroom + (lower_header_len - ETH_HLEN);
+	needed_headroom += batadv_max_header_len();
+
+	/* fragmentation headers don't strip the unicast/... header */
+	needed_headroom += sizeof(struct batadv_frag_packet);
+
+	soft_iface->needed_headroom = needed_headroom;
+	soft_iface->needed_tailroom = lower_tailroom;
+}
+
+/**
+ * batadv_hardif_min_mtu() - Calculate maximum MTU for soft interface
+ * @soft_iface: netdev struct of the soft interface
+ *
+ * Return: MTU for the soft-interface (limited by the minimal MTU of all active
+ *  slave interfaces)
+ */
+int batadv_hardif_min_mtu(struct net_device *soft_iface)
+{
+	struct batadv_priv *bat_priv = netdev_priv(soft_iface);
+	const struct batadv_hard_iface *hard_iface;
+	int min_mtu = INT_MAX;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->if_status != BATADV_IF_ACTIVE &&
+		    hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
+			continue;
+
+		if (hard_iface->soft_iface != soft_iface)
+			continue;
+
+		min_mtu = min_t(int, hard_iface->net_dev->mtu, min_mtu);
+	}
+	rcu_read_unlock();
+
+	if (atomic_read(&bat_priv->fragmentation) == 0)
+		goto out;
+
+	/* with fragmentation enabled the maximum size of internally generated
+	 * packets such as translation table exchanges or tvlv containers, etc
+	 * has to be calculated
+	 */
+	min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
+	min_mtu -= sizeof(struct batadv_frag_packet);
+	min_mtu *= BATADV_FRAG_MAX_FRAGMENTS;
+
+out:
+	/* report to the other components the maximum amount of bytes that
+	 * batman-adv can send over the wire (without considering the payload
+	 * overhead). For example, this value is used by TT to compute the
+	 * maximum local table table size
+	 */
+	atomic_set(&bat_priv->packet_size_max, min_mtu);
+
+	/* the real soft-interface MTU is computed by removing the payload
+	 * overhead from the maximum amount of bytes that was just computed.
+	 *
+	 * However batman-adv does not support MTUs bigger than ETH_DATA_LEN
+	 */
+	return min_t(int, min_mtu - batadv_max_header_len(), ETH_DATA_LEN);
+}
+
+/**
+ * batadv_update_min_mtu() - Adjusts the MTU if a new interface with a smaller
+ *  MTU appeared
+ * @soft_iface: netdev struct of the soft interface
+ */
+void batadv_update_min_mtu(struct net_device *soft_iface)
+{
+	soft_iface->mtu = batadv_hardif_min_mtu(soft_iface);
+
+	/* Check if the local translate table should be cleaned up to match a
+	 * new (and smaller) MTU.
+	 */
+	batadv_tt_local_resize_to_mtu(soft_iface);
+}
+
+static void
+batadv_hardif_activate_interface(struct batadv_hard_iface *hard_iface)
+{
+	struct batadv_priv *bat_priv;
+	struct batadv_hard_iface *primary_if = NULL;
+
+	if (hard_iface->if_status != BATADV_IF_INACTIVE)
+		goto out;
+
+	bat_priv = netdev_priv(hard_iface->soft_iface);
+
+	bat_priv->algo_ops->iface.update_mac(hard_iface);
+	hard_iface->if_status = BATADV_IF_TO_BE_ACTIVATED;
+
+	/* the first active interface becomes our primary interface or
+	 * the next active interface after the old primary interface was removed
+	 */
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		batadv_primary_if_select(bat_priv, hard_iface);
+
+	batadv_info(hard_iface->soft_iface, "Interface activated: %s\n",
+		    hard_iface->net_dev->name);
+
+	batadv_update_min_mtu(hard_iface->soft_iface);
+
+	if (bat_priv->algo_ops->iface.activate)
+		bat_priv->algo_ops->iface.activate(hard_iface);
+
+out:
+	if (primary_if)
+		batadv_hardif_put(primary_if);
+}
+
+static void
+batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
+{
+	if (hard_iface->if_status != BATADV_IF_ACTIVE &&
+	    hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
+		return;
+
+	hard_iface->if_status = BATADV_IF_INACTIVE;
+
+	batadv_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
+		    hard_iface->net_dev->name);
+
+	batadv_update_min_mtu(hard_iface->soft_iface);
+}
+
+/**
+ * batadv_master_del_slave() - remove hard_iface from the current master iface
+ * @slave: the interface enslaved in another master
+ * @master: the master from which slave has to be removed
+ *
+ * Invoke ndo_del_slave on master passing slave as argument. In this way slave
+ * is free'd and master can correctly change its internal state.
+ *
+ * Return: 0 on success, a negative value representing the error otherwise
+ */
+static int batadv_master_del_slave(struct batadv_hard_iface *slave,
+				   struct net_device *master)
+{
+	int ret;
+
+	if (!master)
+		return 0;
+
+	ret = -EBUSY;
+	if (master->netdev_ops->ndo_del_slave)
+		ret = master->netdev_ops->ndo_del_slave(master, slave->net_dev);
+
+	return ret;
+}
+
+/**
+ * batadv_hardif_enable_interface() - Enslave hard interface to soft interface
+ * @hard_iface: hard interface to add to soft interface
+ * @net: the applicable net namespace
+ * @iface_name: name of the soft interface
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
+				   struct net *net, const char *iface_name)
+{
+	struct batadv_priv *bat_priv;
+	struct net_device *soft_iface, *master;
+	__be16 ethertype = htons(ETH_P_BATMAN);
+	int max_header_len = batadv_max_header_len();
+	int ret;
+
+	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
+		goto out;
+
+	kref_get(&hard_iface->refcount);
+
+	soft_iface = dev_get_by_name(net, iface_name);
+
+	if (!soft_iface) {
+		soft_iface = batadv_softif_create(net, iface_name);
+
+		if (!soft_iface) {
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		/* dev_get_by_name() increases the reference counter for us */
+		dev_hold(soft_iface);
+	}
+
+	if (!batadv_softif_is_valid(soft_iface)) {
+		pr_err("Can't create batman mesh interface %s: already exists as regular interface\n",
+		       soft_iface->name);
+		ret = -EINVAL;
+		goto err_dev;
+	}
+
+	/* check if the interface is enslaved in another virtual one and
+	 * in that case unlink it first
+	 */
+	master = netdev_master_upper_dev_get(hard_iface->net_dev);
+	ret = batadv_master_del_slave(hard_iface, master);
+	if (ret)
+		goto err_dev;
+
+	hard_iface->soft_iface = soft_iface;
+	bat_priv = netdev_priv(hard_iface->soft_iface);
+
+	if (bat_priv->num_ifaces >= UINT_MAX) {
+		ret = -ENOSPC;
+		goto err_dev;
+	}
+
+	ret = netdev_master_upper_dev_link(hard_iface->net_dev,
+					   soft_iface, NULL, NULL, NULL);
+	if (ret)
+		goto err_dev;
+
+	ret = bat_priv->algo_ops->iface.enable(hard_iface);
+	if (ret < 0)
+		goto err_upper;
+
+	hard_iface->if_num = bat_priv->num_ifaces;
+	bat_priv->num_ifaces++;
+	hard_iface->if_status = BATADV_IF_INACTIVE;
+	ret = batadv_orig_hash_add_if(hard_iface, bat_priv->num_ifaces);
+	if (ret < 0) {
+		bat_priv->algo_ops->iface.disable(hard_iface);
+		bat_priv->num_ifaces--;
+		hard_iface->if_status = BATADV_IF_NOT_IN_USE;
+		goto err_upper;
+	}
+
+	kref_get(&hard_iface->refcount);
+	hard_iface->batman_adv_ptype.type = ethertype;
+	hard_iface->batman_adv_ptype.func = batadv_batman_skb_recv;
+	hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
+	dev_add_pack(&hard_iface->batman_adv_ptype);
+
+	batadv_info(hard_iface->soft_iface, "Adding interface: %s\n",
+		    hard_iface->net_dev->name);
+
+	if (atomic_read(&bat_priv->fragmentation) &&
+	    hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
+		batadv_info(hard_iface->soft_iface,
+			    "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %i would solve the problem.\n",
+			    hard_iface->net_dev->name, hard_iface->net_dev->mtu,
+			    ETH_DATA_LEN + max_header_len);
+
+	if (!atomic_read(&bat_priv->fragmentation) &&
+	    hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
+		batadv_info(hard_iface->soft_iface,
+			    "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %i.\n",
+			    hard_iface->net_dev->name, hard_iface->net_dev->mtu,
+			    ETH_DATA_LEN + max_header_len);
+
+	if (batadv_hardif_is_iface_up(hard_iface))
+		batadv_hardif_activate_interface(hard_iface);
+	else
+		batadv_err(hard_iface->soft_iface,
+			   "Not using interface %s (retrying later): interface not active\n",
+			   hard_iface->net_dev->name);
+
+	batadv_hardif_recalc_extra_skbroom(soft_iface);
+
+	if (bat_priv->algo_ops->iface.enabled)
+		bat_priv->algo_ops->iface.enabled(hard_iface);
+
+out:
+	return 0;
+
+err_upper:
+	netdev_upper_dev_unlink(hard_iface->net_dev, soft_iface);
+err_dev:
+	hard_iface->soft_iface = NULL;
+	dev_put(soft_iface);
+err:
+	batadv_hardif_put(hard_iface);
+	return ret;
+}
+
+/**
+ * batadv_hardif_disable_interface() - Remove hard interface from soft interface
+ * @hard_iface: hard interface to be removed
+ * @autodel: whether to delete soft interface when it doesn't contain any other
+ *  slave interfaces
+ */
+void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface,
+				     enum batadv_hard_if_cleanup autodel)
+{
+	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+	struct batadv_hard_iface *primary_if = NULL;
+
+	batadv_hardif_deactivate_interface(hard_iface);
+
+	if (hard_iface->if_status != BATADV_IF_INACTIVE)
+		goto out;
+
+	batadv_info(hard_iface->soft_iface, "Removing interface: %s\n",
+		    hard_iface->net_dev->name);
+	dev_remove_pack(&hard_iface->batman_adv_ptype);
+	batadv_hardif_put(hard_iface);
+
+	bat_priv->num_ifaces--;
+	batadv_orig_hash_del_if(hard_iface, bat_priv->num_ifaces);
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (hard_iface == primary_if) {
+		struct batadv_hard_iface *new_if;
+
+		new_if = batadv_hardif_get_active(hard_iface->soft_iface);
+		batadv_primary_if_select(bat_priv, new_if);
+
+		if (new_if)
+			batadv_hardif_put(new_if);
+	}
+
+	bat_priv->algo_ops->iface.disable(hard_iface);
+	hard_iface->if_status = BATADV_IF_NOT_IN_USE;
+
+	/* delete all references to this hard_iface */
+	batadv_purge_orig_ref(bat_priv);
+	batadv_purge_outstanding_packets(bat_priv, hard_iface);
+	dev_put(hard_iface->soft_iface);
+
+	netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface);
+	batadv_hardif_recalc_extra_skbroom(hard_iface->soft_iface);
+
+	/* nobody uses this interface anymore */
+	if (bat_priv->num_ifaces == 0) {
+		batadv_gw_check_client_stop(bat_priv);
+
+		if (autodel == BATADV_IF_CLEANUP_AUTO)
+			batadv_softif_destroy_sysfs(hard_iface->soft_iface);
+	}
+
+	hard_iface->soft_iface = NULL;
+	batadv_hardif_put(hard_iface);
+
+out:
+	if (primary_if)
+		batadv_hardif_put(primary_if);
+}
+
+static struct batadv_hard_iface *
+batadv_hardif_add_interface(struct net_device *net_dev)
+{
+	struct batadv_hard_iface *hard_iface;
+	int ret;
+
+	ASSERT_RTNL();
+
+	if (!batadv_is_valid_iface(net_dev))
+		goto out;
+
+	dev_hold(net_dev);
+
+	hard_iface = kzalloc(sizeof(*hard_iface), GFP_ATOMIC);
+	if (!hard_iface)
+		goto release_dev;
+
+	ret = batadv_sysfs_add_hardif(&hard_iface->hardif_obj, net_dev);
+	if (ret)
+		goto free_if;
+
+	hard_iface->if_num = 0;
+	hard_iface->net_dev = net_dev;
+	hard_iface->soft_iface = NULL;
+	hard_iface->if_status = BATADV_IF_NOT_IN_USE;
+
+	ret = batadv_debugfs_add_hardif(hard_iface);
+	if (ret)
+		goto free_sysfs;
+
+	INIT_LIST_HEAD(&hard_iface->list);
+	INIT_HLIST_HEAD(&hard_iface->neigh_list);
+
+	mutex_init(&hard_iface->bat_iv.ogm_buff_mutex);
+	spin_lock_init(&hard_iface->neigh_list_lock);
+	kref_init(&hard_iface->refcount);
+
+	hard_iface->num_bcasts = BATADV_NUM_BCASTS_DEFAULT;
+	hard_iface->wifi_flags = batadv_wifi_flags_evaluate(net_dev);
+	if (batadv_is_wifi_hardif(hard_iface))
+		hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
+
+	batadv_v_hardif_init(hard_iface);
+
+	batadv_check_known_mac_addr(hard_iface->net_dev);
+	kref_get(&hard_iface->refcount);
+	list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
+
+	return hard_iface;
+
+free_sysfs:
+	batadv_sysfs_del_hardif(&hard_iface->hardif_obj);
+free_if:
+	kfree(hard_iface);
+release_dev:
+	dev_put(net_dev);
+out:
+	return NULL;
+}
+
+static void batadv_hardif_remove_interface(struct batadv_hard_iface *hard_iface)
+{
+	ASSERT_RTNL();
+
+	/* first deactivate interface */
+	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
+		batadv_hardif_disable_interface(hard_iface,
+						BATADV_IF_CLEANUP_KEEP);
+
+	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
+		return;
+
+	hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
+	batadv_debugfs_del_hardif(hard_iface);
+	batadv_sysfs_del_hardif(&hard_iface->hardif_obj);
+	batadv_hardif_put(hard_iface);
+}
+
+/**
+ * batadv_hardif_remove_interfaces() - Remove all hard interfaces
+ */
+void batadv_hardif_remove_interfaces(void)
+{
+	struct batadv_hard_iface *hard_iface, *hard_iface_tmp;
+
+	rtnl_lock();
+	list_for_each_entry_safe(hard_iface, hard_iface_tmp,
+				 &batadv_hardif_list, list) {
+		list_del_rcu(&hard_iface->list);
+		batadv_hardif_remove_interface(hard_iface);
+	}
+	rtnl_unlock();
+}
+
+/**
+ * batadv_hard_if_event_softif() - Handle events for soft interfaces
+ * @event: NETDEV_* event to handle
+ * @net_dev: net_device which generated an event
+ *
+ * Return: NOTIFY_* result
+ */
+static int batadv_hard_if_event_softif(unsigned long event,
+				       struct net_device *net_dev)
+{
+	struct batadv_priv *bat_priv;
+
+	switch (event) {
+	case NETDEV_REGISTER:
+		batadv_sysfs_add_meshif(net_dev);
+		bat_priv = netdev_priv(net_dev);
+		batadv_softif_create_vlan(bat_priv, BATADV_NO_FLAGS);
+		break;
+	case NETDEV_CHANGENAME:
+		batadv_debugfs_rename_meshif(net_dev);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int batadv_hard_if_event(struct notifier_block *this,
+				unsigned long event, void *ptr)
+{
+	struct net_device *net_dev = netdev_notifier_info_to_dev(ptr);
+	struct batadv_hard_iface *hard_iface;
+	struct batadv_hard_iface *primary_if = NULL;
+	struct batadv_priv *bat_priv;
+
+	if (batadv_softif_is_valid(net_dev))
+		return batadv_hard_if_event_softif(event, net_dev);
+
+	hard_iface = batadv_hardif_get_by_netdev(net_dev);
+	if (!hard_iface && (event == NETDEV_REGISTER ||
+			    event == NETDEV_POST_TYPE_CHANGE))
+		hard_iface = batadv_hardif_add_interface(net_dev);
+
+	if (!hard_iface)
+		goto out;
+
+	switch (event) {
+	case NETDEV_UP:
+		batadv_hardif_activate_interface(hard_iface);
+		break;
+	case NETDEV_GOING_DOWN:
+	case NETDEV_DOWN:
+		batadv_hardif_deactivate_interface(hard_iface);
+		break;
+	case NETDEV_UNREGISTER:
+	case NETDEV_PRE_TYPE_CHANGE:
+		list_del_rcu(&hard_iface->list);
+
+		batadv_hardif_remove_interface(hard_iface);
+		break;
+	case NETDEV_CHANGEMTU:
+		if (hard_iface->soft_iface)
+			batadv_update_min_mtu(hard_iface->soft_iface);
+		break;
+	case NETDEV_CHANGEADDR:
+		if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
+			goto hardif_put;
+
+		batadv_check_known_mac_addr(hard_iface->net_dev);
+
+		bat_priv = netdev_priv(hard_iface->soft_iface);
+		bat_priv->algo_ops->iface.update_mac(hard_iface);
+
+		primary_if = batadv_primary_if_get_selected(bat_priv);
+		if (!primary_if)
+			goto hardif_put;
+
+		if (hard_iface == primary_if)
+			batadv_primary_if_update_addr(bat_priv, NULL);
+		break;
+	case NETDEV_CHANGEUPPER:
+		hard_iface->wifi_flags = batadv_wifi_flags_evaluate(net_dev);
+		if (batadv_is_wifi_hardif(hard_iface))
+			hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
+		break;
+	case NETDEV_CHANGENAME:
+		batadv_debugfs_rename_hardif(hard_iface);
+		break;
+	default:
+		break;
+	}
+
+hardif_put:
+	batadv_hardif_put(hard_iface);
+out:
+	if (primary_if)
+		batadv_hardif_put(primary_if);
+	return NOTIFY_DONE;
+}
+
+struct notifier_block batadv_hard_if_notifier = {
+	.notifier_call = batadv_hard_if_event,
+};