diff options
Diffstat (limited to 'net/batman-adv/multicast_forw.c')
| -rw-r--r-- | net/batman-adv/multicast_forw.c | 1178 |
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 0000000000..fafd6ba8c0 --- /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; +} |