From 07afe1ba288c04280622fa002ed385f1ac0b6fe6 Mon Sep 17 00:00:00 2001 From: Linus Lüssing Date: Thu, 7 Sep 2023 03:09:08 +0200 Subject: batman-adv: mcast: implement multicast packet reception and forwarding MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement functionality to receive and forward a new TVLV capable multicast packet type. The new batman-adv multicast packet type allows to contain several originator destination addresses within a TVLV. Routers on the way will potentially split the batman-adv multicast packet and adjust its tracker TVLV contents. Routing decisions are still based on the selected BATMAN IV or BATMAN V routing algorithm. So this new batman-adv multicast packet type retains the same loop-free properties. Also a new OGM multicast TVLV flag is introduced to signal to other nodes that we are capable of handling a batman-adv multicast packet and multicast tracker TVLV. And that all of our hard interfaces have an MTU of at least 1280 bytes (IPv6 minimum MTU), as a simple solution for now to avoid MTU issues while forwarding. Signed-off-by: Linus Lüssing Signed-off-by: Simon Wunderlich --- net/batman-adv/multicast_forw.c | 239 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 239 insertions(+) create mode 100644 net/batman-adv/multicast_forw.c (limited to 'net/batman-adv/multicast_forw.c') diff --git a/net/batman-adv/multicast_forw.c b/net/batman-adv/multicast_forw.c new file mode 100644 index 000000000000..d17341dfb832 --- /dev/null +++ b/net/batman-adv/multicast_forw.c @@ -0,0 +1,239 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) B.A.T.M.A.N. contributors: + * + * Linus Lüssing + */ + +#include "multicast.h" +#include "main.h" + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "originator.h" +#include "send.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_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_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_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); +} -- cgit