path: root/net/batman-adv/multicast_forw.c

// 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