Merge tag 'net-next-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Paolo Abeni:
 "The most interesting thing is probably the networking structs
  reorganization and a significant amount of changes is around
  self-tests.

  Core & protocols:

   - Analyze and reorganize core networking structs (socks, netdev,
     netns, mibs) to optimize cacheline consumption and set up build
     time warnings to safeguard against future header changes

     This improves TCP performances with many concurrent connections up
     to 40%

   - Add page-pool netlink-based introspection, exposing the memory
     usage and recycling stats. This helps indentify bad PP users and
     possible leaks

   - Refine TCP/DCCP source port selection to no longer favor even
     source port at connect() time when IP_LOCAL_PORT_RANGE is set. This
     lowers the time taken by connect() for hosts having many active
     connections to the same destination

   - Refactor the TCP bind conflict code, shrinking related socket
     structs

   - Refactor TCP SYN-Cookie handling, as a preparation step to allow
     arbitrary SYN-Cookie processing via eBPF

   - Tune optmem_max for 0-copy usage, increasing the default value to
     128KB and namespecifying it

   - Allow coalescing for cloned skbs coming from page pools, improving
     RX performances with some common configurations

   - Reduce extension header parsing overhead at GRO time

   - Add bridge MDB bulk deletion support, allowing user-space to
     request the deletion of matching entries

   - Reorder nftables struct members, to keep data accessed by the
     datapath first

   - Introduce TC block ports tracking and use. This allows supporting
     multicast-like behavior at the TC layer

   - Remove UAPI support for retired TC qdiscs (dsmark, CBQ and ATM) and
     classifiers (RSVP and tcindex)

   - More data-race annotations

   - Extend the diag interface to dump TCP bound-only sockets

   - Conditional notification of events for TC qdisc class and actions

   - Support for WPAN dynamic associations with nearby devices, to form
     a sub-network using a specific PAN ID

   - Implement SMCv2.1 virtual ISM device support

   - Add support for Batman-avd mulicast packet type

  BPF:

   - Tons of verifier improvements:
       - BPF register bounds logic and range support along with a large
         test suite
       - log improvements
       - complete precision tracking support for register spills
       - track aligned STACK_ZERO cases as imprecise spilled registers.
         This improves the verifier "instructions processed" metric from
         single digit to 50-60% for some programs
       - support for user's global BPF subprogram arguments with few
         commonly requested annotations for a better developer
         experience
       - support tracking of BPF_JNE which helps cases when the compiler
         transforms (unsigned) "a > 0" into "if a == 0 goto xxx" and the
         like
       - several fixes

   - Add initial TX metadata implementation for AF_XDP with support in
     mlx5 and stmmac drivers. Two types of offloads are supported right
     now, that is, TX timestamp and TX checksum offload

   - Fix kCFI bugs in BPF all forms of indirect calls from BPF into
     kernel and from kernel into BPF work with CFI enabled. This allows
     BPF to work with CONFIG_FINEIBT=y

   - Change BPF verifier logic to validate global subprograms lazily
     instead of unconditionally before the main program, so they can be
     guarded using BPF CO-RE techniques

   - Support uid/gid options when mounting bpffs

   - Add a new kfunc which acquires the associated cgroup of a task
     within a specific cgroup v1 hierarchy where the latter is
     identified by its id

   - Extend verifier to allow bpf_refcount_acquire() of a map value
     field obtained via direct load which is a use-case needed in
     sched_ext

   - Add BPF link_info support for uprobe multi link along with bpftool
     integration for the latter

   - Support for VLAN tag in XDP hints

   - Remove deprecated bpfilter kernel leftovers given the project is
     developed in user-space (https://github.com/facebook/bpfilter)

  Misc:

   - Support for parellel TC self-tests execution

   - Increase MPTCP self-tests coverage

   - Updated the bridge documentation, including several so-far
     undocumented features

   - Convert all the net self-tests to run in unique netns, to avoid
     random failures due to conflict and allow concurrent runs

   - Add TCP-AO self-tests

   - Add kunit tests for both cfg80211 and mac80211

   - Autogenerate Netlink families documentation from YAML spec

   - Add yml-gen support for fixed headers and recursive nests, the tool
     can now generate user-space code for all genetlink families for
     which we have specs

   - A bunch of additional module descriptions fixes

   - Catch incorrect freeing of pages belonging to a page pool

  Driver API:

   - Rust abstractions for network PHY drivers; do not cover yet the
     full C API, but already allow implementing functional PHY drivers
     in rust

   - Introduce queue and NAPI support in the netdev Netlink interface,
     allowing complete access to the device <> NAPIs <> queues
     relationship

   - Introduce notifications filtering for devlink to allow control
     application scale to thousands of instances

   - Improve PHY validation, requesting rate matching information for
     each ethtool link mode supported by both the PHY and host

   - Add support for ethtool symmetric-xor RSS hash

   - ACPI based Wifi band RFI (WBRF) mitigation feature for the AMD
     platform

   - Expose pin fractional frequency offset value over new DPLL generic
     netlink attribute

   - Convert older drivers to platform remove callback returning void

   - Add support for PHY package MMD read/write

  New hardware / drivers:

   - Ethernet:
       - Octeon CN10K devices
       - Broadcom 5760X P7
       - Qualcomm SM8550 SoC
       - Texas Instrument DP83TG720S PHY

   - Bluetooth:
       - IMC Networks Bluetooth radio

  Removed:

   - WiFi:
       - libertas 16-bit PCMCIA support
       - Atmel at76c50x drivers
       - HostAP ISA/PCMCIA style 802.11b driver
       - zd1201 802.11b USB dongles
       - Orinoco ISA/PCMCIA 802.11b driver
       - Aviator/Raytheon driver
       - Planet WL3501 driver
       - RNDIS USB 802.11b driver

  Driver updates:

   - Ethernet high-speed NICs:
       - Intel (100G, ice, idpf):
          - allow one by one port representors creation and removal
          - add temperature and clock information reporting
          - add get/set for ethtool's header split ringparam
          - add again FW logging
          - adds support switchdev hardware packet mirroring
          - iavf: implement symmetric-xor RSS hash
          - igc: add support for concurrent physical and free-running
            timers
          - i40e: increase the allowable descriptors
       - nVidia/Mellanox:
          - Preparation for Socket-Direct multi-dev netdev. That will
            allow in future releases combining multiple PFs devices
            attached to different NUMA nodes under the same netdev
       - Broadcom (bnxt):
          - TX completion handling improvements
          - add basic ntuple filter support
          - reduce MSIX vectors usage for MQPRIO offload
          - add VXLAN support, USO offload and TX coalesce completion
            for P7
       - Marvell Octeon EP:
          - xmit-more support
          - add PF-VF mailbox support and use it for FW notifications
            for VFs
       - Wangxun (ngbe/txgbe):
          - implement ethtool functions to operate pause param, ring
            param, coalesce channel number and msglevel
       - Netronome/Corigine (nfp):
          - add flow-steering support
          - support UDP segmentation offload

   - Ethernet NICs embedded, slower, virtual:
       - Xilinx AXI: remove duplicate DMA code adopting the dma engine
         driver
       - stmmac: add support for HW-accelerated VLAN stripping
       - TI AM654x sw: add mqprio, frame preemption & coalescing
       - gve: add support for non-4k page sizes.
       - virtio-net: support dynamic coalescing moderation

   - nVidia/Mellanox Ethernet datacenter switches:
       - allow firmware upgrade without a reboot
       - more flexible support for bridge flooding via the compressed
         FID flooding mode

   - Ethernet embedded switches:
       - Microchip:
          - fine-tune flow control and speed configurations in KSZ8xxx
          - KSZ88X3: enable setting rmii reference
       - Renesas:
          - add jumbo frames support
       - Marvell:
          - 88E6xxx: add "eth-mac" and "rmon" stats support

   - Ethernet PHYs:
       - aquantia: add firmware load support
       - at803x: refactor the driver to simplify adding support for more
         chip variants
       - NXP C45 TJA11xx: Add MACsec offload support

   - Wifi:
       - MediaTek (mt76):
          - NVMEM EEPROM improvements
          - mt7996 Extremely High Throughput (EHT) improvements
          - mt7996 Wireless Ethernet Dispatcher (WED) support
          - mt7996 36-bit DMA support
       - Qualcomm (ath12k):
          - support for a single MSI vector
          - WCN7850: support AP mode
       - Intel (iwlwifi):
          - new debugfs file fw_dbg_clear
          - allow concurrent P2P operation on DFS channels

   - Bluetooth:
       - QCA2066: support HFP offload
       - ISO: more broadcast-related improvements
       - NXP: better recovery in case receiver/transmitter get out of sync"

* tag 'net-next-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1714 commits)
  lan78xx: remove redundant statement in lan78xx_get_eee
  lan743x: remove redundant statement in lan743x_ethtool_get_eee
  bnxt_en: Fix RCU locking for ntuple filters in bnxt_rx_flow_steer()
  bnxt_en: Fix RCU locking for ntuple filters in bnxt_srxclsrldel()
  bnxt_en: Remove unneeded variable in bnxt_hwrm_clear_vnic_filter()
  tcp: Revert no longer abort SYN_SENT when receiving some ICMP
  Revert "mlx5 updates 2023-12-20"
  Revert "net: stmmac: Enable Per DMA Channel interrupt"
  ipvlan: Remove usage of the deprecated ida_simple_xx() API
  ipvlan: Fix a typo in a comment
  net/sched: Remove ipt action tests
  net: stmmac: Use interrupt mode INTM=1 for per channel irq
  net: stmmac: Add support for TX/RX channel interrupt
  net: stmmac: Make MSI interrupt routine generic
  dt-bindings: net: snps,dwmac: per channel irq
  net: phy: at803x: make read_status more generic
  net: phy: at803x: add support for cdt cross short test for qca808x
  net: phy: at803x: refactor qca808x cable test get status function
  net: phy: at803x: generalize cdt fault length function
  net: ethernet: cortina: Drop TSO support
  ...

1 files changed, 1178 insertions, 0 deletions

diff --git a/net/batman-adv/multicast_forw.c b/net/batman-adv/multicast_forw.c
new file mode 100644
index 000000000000..fafd6ba8c056
--- /dev/null
+++ b/net/batman-adv/multicast_forw.c
@@ -0,0 +1,1178 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Linus Lüssing
+ */
+
+#include "multicast.h"
+#include "main.h"
+
+#include <linux/bug.h>
+#include <linux/build_bug.h>
+#include <linux/byteorder/generic.h>
+#include <linux/compiler.h>
+#include <linux/errno.h>
+#include <linux/etherdevice.h>
+#include <linux/gfp.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <linux/ipv6.h>
+#include <linux/limits.h>
+#include <linux/netdevice.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/skbuff.h>
+#include <linux/stddef.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <uapi/linux/batadv_packet.h>
+
+#include "bridge_loop_avoidance.h"
+#include "originator.h"
+#include "send.h"
+#include "translation-table.h"
+
+#define batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) \
+	for (; num_dests; num_dests--, (dest) += ETH_ALEN)
+
+#define batadv_mcast_forw_tracker_for_each_dest2(dest1, dest2, num_dests) \
+	for (; num_dests; num_dests--, (dest1) += ETH_ALEN, (dest2) += ETH_ALEN)
+
+/**
+ * batadv_mcast_forw_skb_push() - skb_push and memorize amount of pushed bytes
+ * @skb: the skb to push onto
+ * @size: the amount of bytes to push
+ * @len: stores the total amount of bytes pushed
+ *
+ * Performs an skb_push() onto the given skb and adds the amount of pushed bytes
+ * to the given len pointer.
+ *
+ * Return: the return value of the skb_push() call.
+ */
+static void *batadv_mcast_forw_skb_push(struct sk_buff *skb, size_t size,
+					unsigned short *len)
+{
+	*len += size;
+	return skb_push(skb, size);
+}
+
+/**
+ * batadv_mcast_forw_push_padding() - push 2 padding bytes to skb's front
+ * @skb: the skb to push onto
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes two padding bytes to the front of the given skb.
+ *
+ * Return: On success a pointer to the first byte of the two pushed padding
+ * bytes within the skb. NULL otherwise.
+ */
+static char *
+batadv_mcast_forw_push_padding(struct sk_buff *skb, unsigned short *tvlv_len)
+{
+	const int pad_len = 2;
+	char *padding;
+
+	if (skb_headroom(skb) < pad_len)
+		return NULL;
+
+	padding = batadv_mcast_forw_skb_push(skb, pad_len, tvlv_len);
+	memset(padding, 0, pad_len);
+
+	return padding;
+}
+
+/**
+ * batadv_mcast_forw_push_est_padding() - push padding bytes if necessary
+ * @skb: the skb to potentially push the padding onto
+ * @count: the (estimated) number of originators the multicast packet needs to
+ *  be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * If the number of destination entries is even then this adds two
+ * padding bytes to the end of the tracker TVLV.
+ *
+ * Return: true on success or if no padding is needed, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_est_padding(struct sk_buff *skb, int count,
+				   unsigned short *tvlv_len)
+{
+	if (!(count % 2) && !batadv_mcast_forw_push_padding(skb, tvlv_len))
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_orig_entry() - get orig_node from an hlist node
+ * @node: the hlist node to get the orig_node from
+ * @entry_offset: the offset of the hlist node within the orig_node struct
+ *
+ * Return: The orig_node containing the hlist node on success, NULL on error.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_orig_entry(struct hlist_node *node,
+			     size_t entry_offset)
+{
+	/* sanity check */
+	switch (entry_offset) {
+	case offsetof(struct batadv_orig_node, mcast_want_all_ipv4_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_ipv6_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_rtr4_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_rtr6_node):
+		break;
+	default:
+		WARN_ON(1);
+		return NULL;
+	}
+
+	return (struct batadv_orig_node *)((void *)node - entry_offset);
+}
+
+/**
+ * batadv_mcast_forw_push_dest() - push an originator MAC address onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination address onto
+ * @vid: the vlan identifier
+ * @orig_node: the originator node to get the MAC address from
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * If the orig_node is a BLA backbone gateway, if there is not enough skb
+ * headroom available or if num_dests is already at its maximum (65535) then
+ * neither the skb nor num_dests is changed. Otherwise the originator's MAC
+ * address is pushed onto the given skb and num_dests incremented by one.
+ *
+ * Return: true if the orig_node is a backbone gateway or if an orig address
+ *  was pushed successfully, false otherwise.
+ */
+static bool batadv_mcast_forw_push_dest(struct batadv_priv *bat_priv,
+					struct sk_buff *skb, unsigned short vid,
+					struct batadv_orig_node *orig_node,
+					unsigned short *num_dests,
+					unsigned short *tvlv_len)
+{
+	BUILD_BUG_ON(sizeof_field(struct batadv_tvlv_mcast_tracker, num_dests)
+		     != sizeof(__be16));
+
+	/* Avoid sending 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 in mode check.
+	 */
+	if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig, vid))
+		return true;
+
+	if (skb_headroom(skb) < ETH_ALEN || *num_dests == U16_MAX)
+		return false;
+
+	batadv_mcast_forw_skb_push(skb, ETH_ALEN, tvlv_len);
+	ether_addr_copy(skb->data, orig_node->orig);
+	(*num_dests)++;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_dests_list() - push originators from list onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @head: the list to gather originators from
+ * @entry_offset: offset of an hlist node in an orig_node structure
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators in the given list onto the given
+ * skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static int batadv_mcast_forw_push_dests_list(struct batadv_priv *bat_priv,
+					     struct sk_buff *skb,
+					     unsigned short vid,
+					     struct hlist_head *head,
+					     size_t entry_offset,
+					     unsigned short *num_dests,
+					     unsigned short *tvlv_len)
+{
+	struct hlist_node *node;
+	struct batadv_orig_node *orig_node;
+
+	rcu_read_lock();
+	__hlist_for_each_rcu(node, head) {
+		orig_node = batadv_mcast_forw_orig_entry(node, entry_offset);
+		if (!orig_node ||
+		    !batadv_mcast_forw_push_dest(bat_priv, skb, vid, orig_node,
+						 num_dests, tvlv_len)) {
+			rcu_read_unlock();
+			return false;
+		}
+	}
+	rcu_read_unlock();
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_tt() - push originators with interest through TT
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the translation table onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_tt(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			  unsigned short vid, unsigned short *num_dests,
+			  unsigned short *tvlv_len)
+{
+	struct batadv_tt_orig_list_entry *orig_entry;
+
+	struct batadv_tt_global_entry *tt_global;
+	const u8 *addr = eth_hdr(skb)->h_dest;
+
+	/* ok */
+	int ret = true;
+
+	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) {
+		if (!batadv_mcast_forw_push_dest(bat_priv, skb, vid,
+						 orig_entry->orig_node,
+						 num_dests, tvlv_len)) {
+			ret = false;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	batadv_tt_global_entry_put(tt_global);
+
+out:
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_push_want_all() - push originators with want-all flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the want-all flag onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_want_all(struct batadv_priv *bat_priv,
+					    struct sk_buff *skb,
+					    unsigned short vid,
+					    unsigned short *num_dests,
+					    unsigned short *tvlv_len)
+{
+	struct hlist_head *head = NULL;
+	size_t offset;
+	int ret;
+
+	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_IP):
+		head = &bat_priv->mcast.want_all_ipv4_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_ipv4_node);
+		break;
+	case htons(ETH_P_IPV6):
+		head = &bat_priv->mcast.want_all_ipv6_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_ipv6_node);
+		break;
+	default:
+		return false;
+	}
+
+	ret = batadv_mcast_forw_push_dests_list(bat_priv, skb, vid, head,
+						offset, num_dests, tvlv_len);
+	if (!ret)
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_want_rtr() - push originators with want-router flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the want-all-rtr flag onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_want_rtr(struct batadv_priv *bat_priv,
+					    struct sk_buff *skb,
+					    unsigned short vid,
+					    unsigned short *num_dests,
+					    unsigned short *tvlv_len)
+{
+	struct hlist_head *head = NULL;
+	size_t offset;
+	int ret;
+
+	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_IP):
+		head = &bat_priv->mcast.want_all_rtr4_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_rtr4_node);
+		break;
+	case htons(ETH_P_IPV6):
+		head = &bat_priv->mcast.want_all_rtr6_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_rtr6_node);
+		break;
+	default:
+		return false;
+	}
+
+	ret = batadv_mcast_forw_push_dests_list(bat_priv, skb, vid, head,
+						offset, num_dests, tvlv_len);
+	if (!ret)
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_scrape() - remove bytes within skb data
+ * @skb: the skb to remove bytes from
+ * @offset: the offset from the skb data from which to scrape
+ * @len: the amount of bytes to scrape starting from the offset
+ *
+ * Scrapes/removes len bytes from the given skb at the given offset from the
+ * skb data.
+ *
+ * Caller needs to ensure that the region from the skb data's start up
+ * to/including the to be removed bytes are linearized.
+ */
+static void batadv_mcast_forw_scrape(struct sk_buff *skb,
+				     unsigned short offset,
+				     unsigned short len)
+{
+	char *to, *from;
+
+	SKB_LINEAR_ASSERT(skb);
+
+	to = skb_pull(skb, len);
+	from = to - len;
+
+	memmove(to, from, offset);
+}
+
+/**
+ * batadv_mcast_forw_push_scrape_padding() - remove TVLV padding
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Remove two padding bytes from the end of the multicast tracker TVLV,
+ * from before the payload data.
+ *
+ * Caller needs to ensure that the TVLV bytes are linearized.
+ */
+static void batadv_mcast_forw_push_scrape_padding(struct sk_buff *skb,
+						  unsigned short *tvlv_len)
+{
+	const int pad_len = 2;
+
+	batadv_mcast_forw_scrape(skb, *tvlv_len - pad_len, pad_len);
+	*tvlv_len -= pad_len;
+}
+
+/**
+ * batadv_mcast_forw_push_insert_padding() - insert TVLV padding
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Inserts two padding bytes at the end of the multicast tracker TVLV,
+ * before the payload data in the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_insert_padding(struct sk_buff *skb,
+						  unsigned short *tvlv_len)
+{
+	unsigned short offset =	*tvlv_len;
+	char *to, *from = skb->data;
+
+	to = batadv_mcast_forw_push_padding(skb, tvlv_len);
+	if (!to)
+		return false;
+
+	memmove(to, from, offset);
+	memset(to + offset, 0, *tvlv_len - offset);
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_adjust_padding() - adjust padding if necessary
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @count: the estimated number of originators the multicast packet needs to
+ *  be sent to
+ * @num_dests_pushed: the number of originators that were actually added to the
+ *  multicast packet's tracker TVLV
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Adjusts the padding in the multicast packet's tracker TVLV depending on the
+ * initially estimated amount of destinations versus the amount of destinations
+ * that were actually added to the tracker TVLV.
+ *
+ * If the initial estimate was correct or at least the oddness was the same then
+ * no padding adjustment is performed.
+ * If the initially estimated number was even, so padding was initially added,
+ * but it turned out to be odd then padding is removed.
+ * If the initially estimated number was odd, so no padding was initially added,
+ * but it turned out to be even then padding is added.
+ *
+ * Return: true if no padding adjustment is needed or the adjustment was
+ * successful, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_adjust_padding(struct sk_buff *skb, int *count,
+				      unsigned short num_dests_pushed,
+				      unsigned short *tvlv_len)
+{
+	int ret = true;
+
+	if (likely((num_dests_pushed % 2) == (*count % 2)))
+		goto out;
+
+	/**
+	 * estimated even number of destinations, but turned out to be odd
+	 * -> remove padding
+	 */
+	if (!(*count % 2) && (num_dests_pushed % 2))
+		batadv_mcast_forw_push_scrape_padding(skb, tvlv_len);
+	/**
+	 * estimated odd number of destinations, but turned out to be even
+	 * -> add padding
+	 */
+	else if ((*count % 2) && (!(num_dests_pushed % 2)))
+		ret = batadv_mcast_forw_push_insert_padding(skb, tvlv_len);
+
+out:
+	*count = num_dests_pushed;
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_push_dests() - push originator addresses onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet onto the given skb.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_dests(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			     unsigned short vid, int is_routable, int *count,
+			     unsigned short *tvlv_len)
+{
+	unsigned short num_dests = 0;
+
+	if (!batadv_mcast_forw_push_est_padding(skb, *count, tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_tt(bat_priv, skb, vid, &num_dests,
+				       tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_want_all(bat_priv, skb, vid, &num_dests,
+					     tvlv_len))
+		goto err;
+
+	if (is_routable &&
+	    !batadv_mcast_forw_push_want_rtr(bat_priv, skb, vid, &num_dests,
+					     tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_adjust_padding(skb, count, num_dests,
+						   tvlv_len))
+		goto err;
+
+	return 0;
+err:
+	return -ENOMEM;
+}
+
+/**
+ * batadv_mcast_forw_push_tracker() - push a multicast tracker TVLV header
+ * @skb: the skb to push the tracker TVLV onto
+ * @num_dests: the number of destination addresses to set in the header
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes a multicast tracker TVLV header onto the given skb, including the
+ * generic TVLV header but excluding the destination MAC addresses.
+ *
+ * The provided num_dests value is taken into consideration to set the
+ * num_dests field in the tracker header and to set the appropriate TVLV length
+ * value fields.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int batadv_mcast_forw_push_tracker(struct sk_buff *skb, int num_dests,
+					  unsigned short *tvlv_len)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_tvlv_hdr *tvlv_hdr;
+	unsigned int tvlv_value_len;
+
+	if (skb_headroom(skb) < sizeof(*mcast_tracker) + sizeof(*tvlv_hdr))
+		return -ENOMEM;
+
+	tvlv_value_len = sizeof(*mcast_tracker) + *tvlv_len;
+	if (tvlv_value_len + sizeof(*tvlv_hdr) > U16_MAX)
+		return -ENOMEM;
+
+	batadv_mcast_forw_skb_push(skb, sizeof(*mcast_tracker), tvlv_len);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb->data;
+	mcast_tracker->num_dests = htons(num_dests);
+
+	skb_reset_network_header(skb);
+
+	batadv_mcast_forw_skb_push(skb, sizeof(*tvlv_hdr), tvlv_len);
+	tvlv_hdr = (struct batadv_tvlv_hdr *)skb->data;
+	tvlv_hdr->type = BATADV_TVLV_MCAST_TRACKER;
+	tvlv_hdr->version = 1;
+	tvlv_hdr->len = htons(tvlv_value_len);
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push_tvlvs() - push a multicast tracker TVLV onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the tracker TVLV onto
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes a multicast tracker TVLV onto the given skb, including the collected
+ * destination MAC addresses and the generic TVLV header.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_tvlvs(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			     unsigned short vid, int is_routable, int count,
+			     unsigned short *tvlv_len)
+{
+	int ret;
+
+	ret = batadv_mcast_forw_push_dests(bat_priv, skb, vid, is_routable,
+					   &count, tvlv_len);
+	if (ret < 0)
+		return ret;
+
+	ret = batadv_mcast_forw_push_tracker(skb, count, tvlv_len);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push_hdr() - push a multicast packet header onto an skb
+ * @skb: the skb to push the header onto
+ * @tvlv_len: the total TVLV length value to set in the header
+ *
+ * Pushes a batman-adv multicast packet header onto the given skb and sets
+ * the provided total TVLV length value in it.
+ *
+ * Caller needs to ensure enough skb headroom is available.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_hdr(struct sk_buff *skb, unsigned short tvlv_len)
+{
+	struct batadv_mcast_packet *mcast_packet;
+
+	if (skb_headroom(skb) < sizeof(*mcast_packet))
+		return -ENOMEM;
+
+	skb_push(skb, sizeof(*mcast_packet));
+
+	mcast_packet = (struct batadv_mcast_packet *)skb->data;
+	mcast_packet->version = BATADV_COMPAT_VERSION;
+	mcast_packet->ttl = BATADV_TTL;
+	mcast_packet->packet_type = BATADV_MCAST;
+	mcast_packet->reserved = 0;
+	mcast_packet->tvlv_len = htons(tvlv_len);
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_scrub_dests() - scrub destinations in a tracker TVLV
+ * @bat_priv: the bat priv with all the soft interface information
+ * @comp_neigh: next hop neighbor to scrub+collect destinations for
+ * @dest: start MAC entry in original skb's tracker TVLV
+ * @next_dest: start MAC entry in to be sent skb's tracker TVLV
+ * @num_dests: number of remaining destination MAC entries to iterate over
+ *
+ * This sorts destination entries into either the original batman-adv
+ * multicast packet or the skb (copy) that is going to be sent to comp_neigh
+ * next.
+ *
+ * In preparation for the next, to be (unicast) transmitted batman-adv multicast
+ * packet skb to be sent to the given neighbor node, tries to collect all
+ * originator MAC addresses that have the given neighbor node as their next hop
+ * in the to be transmitted skb (copy), which next_dest points into. That is we
+ * zero all destination entries in next_dest which do not have comp_neigh as
+ * their next hop. And zero all destination entries in the original skb that
+ * would have comp_neigh as their next hop (to avoid redundant transmissions and
+ * duplicated payload later).
+ */
+static void
+batadv_mcast_forw_scrub_dests(struct batadv_priv *bat_priv,
+			      struct batadv_neigh_node *comp_neigh, u8 *dest,
+			      u8 *next_dest, u16 num_dests)
+{
+	struct batadv_neigh_node *next_neigh;
+
+	/* skip first entry, this is what we are comparing with */
+	eth_zero_addr(dest);
+	dest += ETH_ALEN;
+	next_dest += ETH_ALEN;
+	num_dests--;
+
+	batadv_mcast_forw_tracker_for_each_dest2(dest, next_dest, num_dests) {
+		if (is_zero_ether_addr(next_dest))
+			continue;
+
+		/* sanity check, we expect unicast destinations */
+		if (is_multicast_ether_addr(next_dest)) {
+			eth_zero_addr(dest);
+			eth_zero_addr(next_dest);
+			continue;
+		}
+
+		next_neigh = batadv_orig_to_router(bat_priv, next_dest, NULL);
+		if (!next_neigh) {
+			eth_zero_addr(next_dest);
+			continue;
+		}
+
+		if (!batadv_compare_eth(next_neigh->addr, comp_neigh->addr)) {
+			eth_zero_addr(next_dest);
+			batadv_neigh_node_put(next_neigh);
+			continue;
+		}
+
+		/* found an entry for our next packet to transmit, so remove it
+		 * from the original packet
+		 */
+		eth_zero_addr(dest);
+		batadv_neigh_node_put(next_neigh);
+	}
+}
+
+/**
+ * batadv_mcast_forw_shrink_fill() - swap slot with next non-zero destination
+ * @slot: the to be filled zero-MAC destination entry in a tracker TVLV
+ * @num_dests_slot: remaining entries in tracker TVLV from/including slot
+ *
+ * Searches for the next non-zero-MAC destination entry in a tracker TVLV after
+ * the given slot pointer. And if found, swaps it with the zero-MAC destination
+ * entry which the slot points to.
+ *
+ * Return: true if slot was swapped/filled successfully, false otherwise.
+ */
+static bool batadv_mcast_forw_shrink_fill(u8 *slot, u16 num_dests_slot)
+{
+	u16 num_dests_filler;
+	u8 *filler;
+
+	/* sanity check, should not happen */
+	if (!num_dests_slot)
+		return false;
+
+	num_dests_filler = num_dests_slot - 1;
+	filler = slot + ETH_ALEN;
+
+	/* find a candidate to fill the empty slot */
+	batadv_mcast_forw_tracker_for_each_dest(filler, num_dests_filler) {
+		if (is_zero_ether_addr(filler))
+			continue;
+
+		ether_addr_copy(slot, filler);
+		eth_zero_addr(filler);
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * batadv_mcast_forw_shrink_pack_dests() - pack destinations of a tracker TVLV
+ * @skb: the batman-adv multicast packet to compact destinations in
+ *
+ * Compacts the originator destination MAC addresses in the multicast tracker
+ * TVLV of the given multicast packet. This is done by moving all non-zero
+ * MAC addresses in direction of the skb head and all zero MAC addresses in skb
+ * tail direction, within the multicast tracker TVLV.
+ *
+ * Return: The number of consecutive zero MAC address destinations which are
+ * now at the end of the multicast tracker TVLV.
+ */
+static int batadv_mcast_forw_shrink_pack_dests(struct sk_buff *skb)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	unsigned char *skb_net_hdr;
+	u16 num_dests_slot;
+	u8 *slot;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests_slot = ntohs(mcast_tracker->num_dests);
+
+	slot = (u8 *)mcast_tracker + sizeof(*mcast_tracker);
+
+	batadv_mcast_forw_tracker_for_each_dest(slot, num_dests_slot) {
+		/* find an empty slot */
+		if (!is_zero_ether_addr(slot))
+			continue;
+
+		if (!batadv_mcast_forw_shrink_fill(slot, num_dests_slot))
+			/* could not find a filler, so we successfully packed
+			 * and can stop - and must not reduce num_dests_slot!
+			 */
+			break;
+	}
+
+	/* num_dests_slot is now the amount of reduced, zeroed
+	 * destinations at the end of the tracker TVLV
+	 */
+	return num_dests_slot;
+}
+
+/**
+ * batadv_mcast_forw_shrink_align_offset() - get new alignment offset
+ * @num_dests_old: the old, to be updated amount of destination nodes
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * Calculates the amount of potential extra alignment offset that is needed to
+ * adjust the TVLV padding after the change in destination nodes.
+ *
+ * Return:
+ *	0: If no change to padding is needed.
+ *	2: If padding needs to be removed.
+ *	-2: If padding needs to be added.
+ */
+static short
+batadv_mcast_forw_shrink_align_offset(unsigned int num_dests_old,
+				      unsigned int num_dests_reduce)
+{
+	/* even amount of removed destinations -> no alignment change */
+	if (!(num_dests_reduce % 2))
+		return 0;
+
+	/* even to odd amount of destinations -> remove padding */
+	if (!(num_dests_old % 2))
+		return 2;
+
+	/* odd to even amount of destinations -> add padding */
+	return -2;
+}
+
+/**
+ * batadv_mcast_forw_shrink_update_headers() - update shrunk mc packet headers
+ * @skb: the batman-adv multicast packet to update headers of
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * This updates any fields of a batman-adv multicast packet that are affected
+ * by the reduced number of destinations in the multicast tracket TVLV. In
+ * particular this updates:
+ *
+ * The num_dest field of the multicast tracker TVLV.
+ * The TVLV length field of the according generic TVLV header.
+ * The batman-adv multicast packet's total TVLV length field.
+ *
+ * Return: The offset in skb's tail direction at which the new batman-adv
+ * multicast packet header needs to start.
+ */
+static unsigned int
+batadv_mcast_forw_shrink_update_headers(struct sk_buff *skb,
+					unsigned int num_dests_reduce)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_mcast_packet *mcast_packet;
+	struct batadv_tvlv_hdr *tvlv_hdr;
+	unsigned char *skb_net_hdr;
+	unsigned int offset;
+	short align_offset;
+	u16 num_dests;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+
+	align_offset = batadv_mcast_forw_shrink_align_offset(num_dests,
+							     num_dests_reduce);
+	offset = ETH_ALEN * num_dests_reduce + align_offset;
+	num_dests -= num_dests_reduce;
+
+	/* update tracker header */
+	mcast_tracker->num_dests = htons(num_dests);
+
+	/* update tracker's tvlv header's length field */
+	tvlv_hdr = (struct batadv_tvlv_hdr *)(skb_network_header(skb) -
+					      sizeof(*tvlv_hdr));
+	tvlv_hdr->len = htons(ntohs(tvlv_hdr->len) - offset);
+
+	/* update multicast packet header's tvlv length field */
+	mcast_packet = (struct batadv_mcast_packet *)skb->data;
+	mcast_packet->tvlv_len = htons(ntohs(mcast_packet->tvlv_len) - offset);
+
+	return offset;
+}
+
+/**
+ * batadv_mcast_forw_shrink_move_headers() - move multicast headers by offset
+ * @skb: the batman-adv multicast packet to move headers for
+ * @offset: a non-negative offset to move headers by, towards the skb tail
+ *
+ * Moves the batman-adv multicast packet header, its multicast tracker TVLV and
+ * any TVLVs in between by the given offset in direction towards the tail.
+ */
+static void
+batadv_mcast_forw_shrink_move_headers(struct sk_buff *skb, unsigned int offset)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	unsigned char *skb_net_hdr;
+	unsigned int len;
+	u16 num_dests;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+	len = skb_network_offset(skb) + sizeof(*mcast_tracker);
+	len += num_dests * ETH_ALEN;
+
+	batadv_mcast_forw_scrape(skb, len, offset);
+}
+
+/**
+ * batadv_mcast_forw_shrink_tracker() - remove zero addresses in a tracker tvlv
+ * @skb: the batman-adv multicast packet to (potentially) shrink
+ *
+ * Removes all destinations with a zero MAC addresses (00:00:00:00:00:00) from
+ * the given batman-adv multicast packet's tracker TVLV and updates headers
+ * accordingly to maintain a valid batman-adv multicast packet.
+ */
+static void batadv_mcast_forw_shrink_tracker(struct sk_buff *skb)
+{
+	unsigned int offset;
+	u16 dests_reduced;
+
+	dests_reduced = batadv_mcast_forw_shrink_pack_dests(skb);
+	if (!dests_reduced)
+		return;
+
+	offset = batadv_mcast_forw_shrink_update_headers(skb, dests_reduced);
+	batadv_mcast_forw_shrink_move_headers(skb, offset);
+}
+
+/**
+ * batadv_mcast_forw_packet() - forward a batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the received or locally generated batman-adv multicast packet
+ * @local_xmit: indicates that the packet was locally generated and not received
+ *
+ * Parses the tracker TVLV of a batman-adv multicast packet and forwards the
+ * packet as indicated in this TVLV.
+ *
+ * Caller needs to set the skb network header to the start of the multicast
+ * tracker TVLV (excluding the generic TVLV header) and the skb transport header
+ * to the next byte after this multicast tracker TVLV.
+ *
+ * Caller needs to free the skb.
+ *
+ * Return: NET_RX_SUCCESS or NET_RX_DROP on success or a negative error
+ * code on failure. NET_RX_SUCCESS if the received packet is supposed to be
+ * decapsulated and forwarded to the own soft interface, NET_RX_DROP otherwise.
+ */
+static int batadv_mcast_forw_packet(struct batadv_priv *bat_priv,
+				    struct sk_buff *skb, bool local_xmit)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_neigh_node *neigh_node;
+	unsigned long offset, num_dests_off;
+	struct sk_buff *nexthop_skb;
+	unsigned char *skb_net_hdr;
+	bool local_recv = false;
+	unsigned int tvlv_len;
+	bool xmitted = false;
+	u8 *dest, *next_dest;
+	u16 num_dests;
+	int ret;
+
+	/* (at least) TVLV part needs to be linearized */
+	SKB_LINEAR_ASSERT(skb);
+
+	/* check if num_dests is within skb length */
+	num_dests_off = offsetof(struct batadv_tvlv_mcast_tracker, num_dests);
+	if (num_dests_off > skb_network_header_len(skb))
+		return -EINVAL;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+
+	dest = (u8 *)mcast_tracker + sizeof(*mcast_tracker);
+
+	/* check if full tracker tvlv is within skb length */
+	tvlv_len = sizeof(*mcast_tracker) + ETH_ALEN * num_dests;
+	if (tvlv_len > skb_network_header_len(skb))
+		return -EINVAL;
+
+	/* invalidate checksum: */
+	skb->ip_summed = CHECKSUM_NONE;
+
+	batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) {
+		if (is_zero_ether_addr(dest))
+			continue;
+
+		/* only unicast originator addresses supported */
+		if (is_multicast_ether_addr(dest)) {
+			eth_zero_addr(dest);
+			continue;
+		}
+
+		if (batadv_is_my_mac(bat_priv, dest)) {
+			eth_zero_addr(dest);
+			local_recv = true;
+			continue;
+		}
+
+		neigh_node = batadv_orig_to_router(bat_priv, dest, NULL);
+		if (!neigh_node) {
+			eth_zero_addr(dest);
+			continue;
+		}
+
+		nexthop_skb = skb_copy(skb, GFP_ATOMIC);
+		if (!nexthop_skb) {
+			batadv_neigh_node_put(neigh_node);
+			return -ENOMEM;
+		}
+
+		offset = dest - skb->data;
+		next_dest = nexthop_skb->data + offset;
+
+		batadv_mcast_forw_scrub_dests(bat_priv, neigh_node, dest,
+					      next_dest, num_dests);
+		batadv_mcast_forw_shrink_tracker(nexthop_skb);
+
+		batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_TX);
+		batadv_add_counter(bat_priv, BATADV_CNT_MCAST_TX_BYTES,
+				   nexthop_skb->len + ETH_HLEN);
+		xmitted = true;
+		ret = batadv_send_unicast_skb(nexthop_skb, neigh_node);
+
+		batadv_neigh_node_put(neigh_node);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	if (xmitted) {
+		if (local_xmit) {
+			batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_TX_LOCAL);
+			batadv_add_counter(bat_priv,
+					   BATADV_CNT_MCAST_TX_LOCAL_BYTES,
+					   skb->len -
+					   skb_transport_offset(skb));
+		} else {
+			batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_FWD);
+			batadv_add_counter(bat_priv, BATADV_CNT_MCAST_FWD_BYTES,
+					   skb->len + ETH_HLEN);
+		}
+	}
+
+	if (local_recv)
+		return NET_RX_SUCCESS;
+	else
+		return NET_RX_DROP;
+}
+
+/**
+ * batadv_mcast_forw_tracker_tvlv_handler() - handle an mcast tracker tvlv
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the received batman-adv multicast packet
+ *
+ * Parses the tracker TVLV of an incoming batman-adv multicast packet and
+ * forwards the packet as indicated in this TVLV.
+ *
+ * Caller needs to set the skb network header to the start of the multicast
+ * tracker TVLV (excluding the generic TVLV header) and the skb transport header
+ * to the next byte after this multicast tracker TVLV.
+ *
+ * Caller needs to free the skb.
+ *
+ * Return: NET_RX_SUCCESS or NET_RX_DROP on success or a negative error
+ * code on failure. NET_RX_SUCCESS if the received packet is supposed to be
+ * decapsulated and forwarded to the own soft interface, NET_RX_DROP otherwise.
+ */
+int batadv_mcast_forw_tracker_tvlv_handler(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb)
+{
+	return batadv_mcast_forw_packet(bat_priv, skb, false);
+}
+
+/**
+ * batadv_mcast_forw_packet_hdrlen() - multicast packet header length
+ * @num_dests: number of destination nodes
+ *
+ * Calculates the total batman-adv multicast packet header length for a given
+ * number of destination nodes (excluding the outer ethernet frame).
+ *
+ * Return: The calculated total batman-adv multicast packet header length.
+ */
+unsigned int batadv_mcast_forw_packet_hdrlen(unsigned int num_dests)
+{
+	/**
+	 * If the number of destination entries is even then we need to add
+	 * two byte padding to the tracker TVLV.
+	 */
+	int padding = (!(num_dests % 2)) ? 2 : 0;
+
+	return padding + num_dests * ETH_ALEN +
+	       sizeof(struct batadv_tvlv_mcast_tracker) +
+	       sizeof(struct batadv_tvlv_hdr) +
+	       sizeof(struct batadv_mcast_packet);
+}
+
+/**
+ * batadv_mcast_forw_expand_head() - expand headroom for an mcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to send
+ *
+ * Tries to expand an skb's headroom so that its head to tail is 1298
+ * bytes (minimum IPv6 MTU + vlan ethernet header size) large.
+ *
+ * Return: -EINVAL if the given skb's length is too large or -ENOMEM on memory
+ * allocation failure. Otherwise, on success, zero is returned.
+ */
+static int batadv_mcast_forw_expand_head(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb)
+{
+	int hdr_size = VLAN_ETH_HLEN + IPV6_MIN_MTU - skb->len;
+
+	 /* TODO: Could be tightened to actual number of destination nodes?
+	  * But it's tricky, number of destinations might have increased since
+	  * we last checked.
+	  */
+	if (hdr_size < 0) {
+		/* batadv_mcast_forw_mode_check_count() should ensure we do not
+		 * end up here
+		 */
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	if (skb_headroom(skb) < hdr_size &&
+	    pskb_expand_head(skb, hdr_size, 0, GFP_ATOMIC) < 0)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push() - encapsulate skb in a batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to encapsulate and send
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ *
+ * Encapsulates the given multicast packet in a batman-adv multicast packet.
+ * A multicast tracker TVLV with destination originator addresses for any node
+ * that signaled interest in it, that is either via the translation table or the
+ * according want-all flags, is attached accordingly.
+ *
+ * Return: true on success, false otherwise.
+ */
+bool batadv_mcast_forw_push(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			    unsigned short vid, int is_routable, int count)
+{
+	unsigned short tvlv_len = 0;
+	int ret;
+
+	if (batadv_mcast_forw_expand_head(bat_priv, skb) < 0)
+		goto err;
+
+	skb_reset_transport_header(skb);
+
+	ret = batadv_mcast_forw_push_tvlvs(bat_priv, skb, vid, is_routable,
+					   count, &tvlv_len);
+	if (ret < 0)
+		goto err;
+
+	ret = batadv_mcast_forw_push_hdr(skb, tvlv_len);
+	if (ret < 0)
+		goto err;
+
+	return true;
+
+err:
+	if (tvlv_len)
+		skb_pull(skb, tvlv_len);
+
+	return false;
+}
+
+/**
+ * batadv_mcast_forw_mcsend() - send a self prepared batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to encapsulate and send
+ *
+ * Transmits a batman-adv multicast packet that was locally prepared and
+ * consumes/frees it.
+ *
+ * Return: NET_XMIT_DROP on memory allocation failure. NET_XMIT_SUCCESS
+ * otherwise.
+ */
+int batadv_mcast_forw_mcsend(struct batadv_priv *bat_priv,
+			     struct sk_buff *skb)
+{
+	int ret = batadv_mcast_forw_packet(bat_priv, skb, true);
+
+	if (ret < 0) {
+		kfree_skb(skb);
+		return NET_XMIT_DROP;
+	}
+
+	consume_skb(skb);
+	return NET_XMIT_SUCCESS;
+}