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kernel/net/batman-adv/distributed-arp-table.c

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// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) B.A.T.M.A.N. contributors:
*
* Antonio Quartulli
*/
#include "distributed-arp-table.h"
#include "main.h"
#include <linux/unaligned.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/byteorder/generic.h>
#include <linux/container_of.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/gfp.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/jiffies.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/udp.h>
#include <linux/workqueue.h>
#include <net/arp.h>
#include <net/genetlink.h>
#include <net/netlink.h>
#include <net/sock.h>
#include <uapi/linux/batman_adv.h>
#include "bridge_loop_avoidance.h"
#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "netlink.h"
#include "originator.h"
#include "send.h"
#include "soft-interface.h"
#include "translation-table.h"
#include "tvlv.h"
enum batadv_bootpop {
BATADV_BOOTREPLY = 2,
};
enum batadv_boothtype {
BATADV_HTYPE_ETHERNET = 1,
};
enum batadv_dhcpoptioncode {
BATADV_DHCP_OPT_PAD = 0,
BATADV_DHCP_OPT_MSG_TYPE = 53,
BATADV_DHCP_OPT_END = 255,
};
enum batadv_dhcptype {
BATADV_DHCPACK = 5,
};
/* { 99, 130, 83, 99 } */
#define BATADV_DHCP_MAGIC 1669485411
struct batadv_dhcp_packet {
__u8 op;
__u8 htype;
__u8 hlen;
__u8 hops;
__be32 xid;
__be16 secs;
__be16 flags;
__be32 ciaddr;
__be32 yiaddr;
__be32 siaddr;
__be32 giaddr;
__u8 chaddr[16];
__u8 sname[64];
__u8 file[128];
__be32 magic;
/* __u8 options[]; */
};
#define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
#define BATADV_DHCP_CHADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->chaddr)
static void batadv_dat_purge(struct work_struct *work);
/**
* batadv_dat_start_timer() - initialise the DAT periodic worker
* @bat_priv: the bat priv with all the soft interface information
*/
static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
{
queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
msecs_to_jiffies(10000));
}
/**
* batadv_dat_entry_release() - release dat_entry from lists and queue for free
* after rcu grace period
* @ref: kref pointer of the dat_entry
*/
static void batadv_dat_entry_release(struct kref *ref)
{
struct batadv_dat_entry *dat_entry;
dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
kfree_rcu(dat_entry, rcu);
}
/**
* batadv_dat_entry_put() - decrement the dat_entry refcounter and possibly
* release it
* @dat_entry: dat_entry to be free'd
*/
static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
{
if (!dat_entry)
return;
kref_put(&dat_entry->refcount, batadv_dat_entry_release);
}
/**
* batadv_dat_to_purge() - check whether a dat_entry has to be purged or not
* @dat_entry: the entry to check
*
* Return: true if the entry has to be purged now, false otherwise.
*/
static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
{
return batadv_has_timed_out(dat_entry->last_update,
BATADV_DAT_ENTRY_TIMEOUT);
}
/**
* __batadv_dat_purge() - delete entries from the DAT local storage
* @bat_priv: the bat priv with all the soft interface information
* @to_purge: function in charge to decide whether an entry has to be purged or
* not. This function takes the dat_entry as argument and has to
* returns a boolean value: true is the entry has to be deleted,
* false otherwise
*
* Loops over each entry in the DAT local storage and deletes it if and only if
* the to_purge function passed as argument returns true.
*/
static void __batadv_dat_purge(struct batadv_priv *bat_priv,
bool (*to_purge)(struct batadv_dat_entry *))
{
spinlock_t *list_lock; /* protects write access to the hash lists */
struct batadv_dat_entry *dat_entry;
struct hlist_node *node_tmp;
struct hlist_head *head;
u32 i;
if (!bat_priv->dat.hash)
return;
for (i = 0; i < bat_priv->dat.hash->size; i++) {
head = &bat_priv->dat.hash->table[i];
list_lock = &bat_priv->dat.hash->list_locks[i];
spin_lock_bh(list_lock);
hlist_for_each_entry_safe(dat_entry, node_tmp, head,
hash_entry) {
/* if a helper function has been passed as parameter,
* ask it if the entry has to be purged or not
*/
if (to_purge && !to_purge(dat_entry))
continue;
hlist_del_rcu(&dat_entry->hash_entry);
batadv_dat_entry_put(dat_entry);
}
spin_unlock_bh(list_lock);
}
}
/**
* batadv_dat_purge() - periodic task that deletes old entries from the local
* DAT hash table
* @work: kernel work struct
*/
static void batadv_dat_purge(struct work_struct *work)
{
struct delayed_work *delayed_work;
struct batadv_priv_dat *priv_dat;
struct batadv_priv *bat_priv;
delayed_work = to_delayed_work(work);
priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
bat_priv = container_of(priv_dat, struct batadv_priv, dat);
__batadv_dat_purge(bat_priv, batadv_dat_to_purge);
batadv_dat_start_timer(bat_priv);
}
/**
* batadv_compare_dat() - comparing function used in the local DAT hash table
* @node: node in the local table
* @data2: second object to compare the node to
*
* Return: true if the two entries are the same, false otherwise.
*/
static bool batadv_compare_dat(const struct hlist_node *node, const void *data2)
{
const void *data1 = container_of(node, struct batadv_dat_entry,
hash_entry);
return memcmp(data1, data2, sizeof(__be32)) == 0;
}
/**
* batadv_arp_hw_src() - extract the hw_src field from an ARP packet
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
*
* Return: the value of the hw_src field in the ARP packet.
*/
static u8 *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
{
u8 *addr;
addr = (u8 *)(skb->data + hdr_size);
addr += ETH_HLEN + sizeof(struct arphdr);
return addr;
}
/**
* batadv_arp_ip_src() - extract the ip_src field from an ARP packet
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
*
* Return: the value of the ip_src field in the ARP packet.
*/
static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
{
return *(__force __be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
}
/**
* batadv_arp_hw_dst() - extract the hw_dst field from an ARP packet
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
*
* Return: the value of the hw_dst field in the ARP packet.
*/
static u8 *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
{
return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
}
/**
* batadv_arp_ip_dst() - extract the ip_dst field from an ARP packet
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
*
* Return: the value of the ip_dst field in the ARP packet.
*/
static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
{
u8 *dst = batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4;
return *(__force __be32 *)dst;
}
/**
* batadv_hash_dat() - compute the hash value for an IP address
* @data: data to hash
* @size: size of the hash table
*
* Return: the selected index in the hash table for the given data.
*/
static u32 batadv_hash_dat(const void *data, u32 size)
{
u32 hash = 0;
const struct batadv_dat_entry *dat = data;
const unsigned char *key;
__be16 vid;
u32 i;
key = (__force const unsigned char *)&dat->ip;
for (i = 0; i < sizeof(dat->ip); i++) {
hash += key[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
vid = htons(dat->vid);
key = (__force const unsigned char *)&vid;
for (i = 0; i < sizeof(dat->vid); i++) {
hash += key[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
return hash % size;
}
/**
* batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
* table
* @bat_priv: the bat priv with all the soft interface information
* @ip: search key
* @vid: VLAN identifier
*
* Return: the dat_entry if found, NULL otherwise.
*/
static struct batadv_dat_entry *
batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
unsigned short vid)
{
struct hlist_head *head;
struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
struct batadv_hashtable *hash = bat_priv->dat.hash;
u32 index;
if (!hash)
return NULL;
to_find.ip = ip;
to_find.vid = vid;
index = batadv_hash_dat(&to_find, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
if (dat_entry->ip != ip)
continue;
if (!kref_get_unless_zero(&dat_entry->refcount))
continue;
dat_entry_tmp = dat_entry;
break;
}
rcu_read_unlock();
return dat_entry_tmp;
}
/**
* batadv_dat_entry_add() - add a new dat entry or update it if already exists
* @bat_priv: the bat priv with all the soft interface information
* @ip: ipv4 to add/edit
* @mac_addr: mac address to assign to the given ipv4
* @vid: VLAN identifier
*/
static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
u8 *mac_addr, unsigned short vid)
{
struct batadv_dat_entry *dat_entry;
int hash_added;
dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
/* if this entry is already known, just update it */
if (dat_entry) {
if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
ether_addr_copy(dat_entry->mac_addr, mac_addr);
dat_entry->last_update = jiffies;
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Entry updated: %pI4 %pM (vid: %d)\n",
&dat_entry->ip, dat_entry->mac_addr,
batadv_print_vid(vid));
goto out;
}
dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
if (!dat_entry)
goto out;
dat_entry->ip = ip;
dat_entry->vid = vid;
ether_addr_copy(dat_entry->mac_addr, mac_addr);
dat_entry->last_update = jiffies;
kref_init(&dat_entry->refcount);
kref_get(&dat_entry->refcount);
hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
batadv_hash_dat, dat_entry,
&dat_entry->hash_entry);
if (unlikely(hash_added != 0)) {
/* remove the reference for the hash */
batadv_dat_entry_put(dat_entry);
goto out;
}
batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
&dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
out:
batadv_dat_entry_put(dat_entry);
}
#ifdef CONFIG_BATMAN_ADV_DEBUG
/**
* batadv_dbg_arp() - print a debug message containing all the ARP packet
* details
* @bat_priv: the bat priv with all the soft interface information
* @skb: ARP packet
* @hdr_size: size of the possible header before the ARP packet
* @msg: message to print together with the debugging information
*/
static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
int hdr_size, char *msg)
{
struct batadv_unicast_4addr_packet *unicast_4addr_packet;
struct batadv_bcast_packet *bcast_pkt;
u8 *orig_addr;
__be32 ip_src, ip_dst;
if (msg)
batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
ip_src = batadv_arp_ip_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
batadv_arp_hw_src(skb, hdr_size), &ip_src,
batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
if (hdr_size < sizeof(struct batadv_unicast_packet))
return;
unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
switch (unicast_4addr_packet->u.packet_type) {
case BATADV_UNICAST:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a UNICAST packet\n");
break;
case BATADV_UNICAST_4ADDR:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
unicast_4addr_packet->src);
switch (unicast_4addr_packet->subtype) {
case BATADV_P_DAT_DHT_PUT:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
break;
case BATADV_P_DAT_DHT_GET:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
break;
case BATADV_P_DAT_CACHE_REPLY:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* type: DAT_CACHE_REPLY\n");
break;
case BATADV_P_DATA:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
break;
default:
batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
unicast_4addr_packet->u.packet_type);
}
break;
case BATADV_BCAST:
bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
orig_addr = bcast_pkt->orig;
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within a BCAST packet (src: %pM)\n",
orig_addr);
break;
default:
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"* encapsulated within an unknown packet type (0x%x)\n",
unicast_4addr_packet->u.packet_type);
}
}
#else
static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
int hdr_size, char *msg)
{
}
#endif /* CONFIG_BATMAN_ADV_DEBUG */
/**
* batadv_is_orig_node_eligible() - check whether a node can be a DHT candidate
* @res: the array with the already selected candidates
* @select: number of already selected candidates
* @tmp_max: address of the currently evaluated node
* @max: current round max address
* @last_max: address of the last selected candidate
* @candidate: orig_node under evaluation
* @max_orig_node: last selected candidate
*
* Return: true if the node has been elected as next candidate or false
* otherwise.
*/
static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
int select, batadv_dat_addr_t tmp_max,
batadv_dat_addr_t max,
batadv_dat_addr_t last_max,
struct batadv_orig_node *candidate,
struct batadv_orig_node *max_orig_node)
{
bool ret = false;
int j;
/* check if orig node candidate is running DAT */
if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
goto out;
/* Check if this node has already been selected... */
for (j = 0; j < select; j++)
if (res[j].orig_node == candidate)
break;
/* ..and possibly skip it */
if (j < select)
goto out;
/* sanity check: has it already been selected? This should not happen */
if (tmp_max > last_max)
goto out;
/* check if during this iteration an originator with a closer dht
* address has already been found
*/
if (tmp_max < max)
goto out;
/* this is an hash collision with the temporary selected node. Choose
* the one with the lowest address
*/
if (tmp_max == max && max_orig_node &&
batadv_compare_eth(candidate->orig, max_orig_node->orig))
goto out;
ret = true;
out:
return ret;
}
/**
* batadv_choose_next_candidate() - select the next DHT candidate
* @bat_priv: the bat priv with all the soft interface information
* @cands: candidates array
* @select: number of candidates already present in the array
* @ip_key: key to look up in the DHT
* @last_max: pointer where the address of the selected candidate will be saved
*/
static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
struct batadv_dat_candidate *cands,
int select, batadv_dat_addr_t ip_key,
batadv_dat_addr_t *last_max)
{
batadv_dat_addr_t max = 0;
batadv_dat_addr_t tmp_max = 0;
struct batadv_orig_node *orig_node, *max_orig_node = NULL;
struct batadv_hashtable *hash = bat_priv->orig_hash;
struct hlist_head *head;
int i;
/* if no node is eligible as candidate, leave the candidate type as
* NOT_FOUND
*/
cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
/* iterate over the originator list and find the node with the closest
* dat_address which has not been selected yet
*/
for (i = 0; i < hash->size; i++) {
head = &hash->table[i];
rcu_read_lock();
hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
/* the dht space is a ring using unsigned addresses */
tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
ip_key;
if (!batadv_is_orig_node_eligible(cands, select,
tmp_max, max,
*last_max, orig_node,
max_orig_node))
continue;
if (!kref_get_unless_zero(&orig_node->refcount))
continue;
max = tmp_max;
batadv_orig_node_put(max_orig_node);
max_orig_node = orig_node;
}
rcu_read_unlock();
}
if (max_orig_node) {
cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
cands[select].orig_node = max_orig_node;
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
select, max_orig_node->orig, max_orig_node->dat_addr,
max);
}
*last_max = max;
}
/**
* batadv_dat_select_candidates() - select the nodes which the DHT message has
* to be sent to
* @bat_priv: the bat priv with all the soft interface information
* @ip_dst: ipv4 to look up in the DHT
* @vid: VLAN identifier
*
* An originator O is selected if and only if its DHT_ID value is one of three
* closest values (from the LEFT, with wrap around if needed) then the hash
* value of the key. ip_dst is the key.
*
* Return: the candidate array of size BATADV_DAT_CANDIDATE_NUM.
*/
static struct batadv_dat_candidate *
batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
unsigned short vid)
{
int select;
batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
struct batadv_dat_candidate *res;
struct batadv_dat_entry dat;
if (!bat_priv->orig_hash)
return NULL;
res = kmalloc_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
GFP_ATOMIC);
if (!res)
return NULL;
dat.ip = ip_dst;
dat.vid = vid;
ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
BATADV_DAT_ADDR_MAX);
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"%s(): IP=%pI4 hash(IP)=%u\n", __func__, &ip_dst,
ip_key);
for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
batadv_choose_next_candidate(bat_priv, res, select, ip_key,
&last_max);
return res;
}
/**
* batadv_dat_forward_data() - copy and send payload to the selected candidates
* @bat_priv: the bat priv with all the soft interface information
* @skb: payload to send
* @ip: the DHT key
* @vid: VLAN identifier
* @packet_subtype: unicast4addr packet subtype to use
*
* This function copies the skb with pskb_copy() and is sent as a unicast packet
* to each of the selected candidates.
*
* Return: true if the packet is sent to at least one candidate, false
* otherwise.
*/
static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
struct sk_buff *skb, __be32 ip,
unsigned short vid, int packet_subtype)
{
int i;
bool ret = false;
int send_status;
struct batadv_neigh_node *neigh_node = NULL;
struct sk_buff *tmp_skb;
struct batadv_dat_candidate *cand;
cand = batadv_dat_select_candidates(bat_priv, ip, vid);
if (!cand)
return ret;
batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
continue;
neigh_node = batadv_orig_router_get(cand[i].orig_node,
BATADV_IF_DEFAULT);
if (!neigh_node)
goto free_orig;
tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
cand[i].orig_node,
packet_subtype)) {
kfree_skb(tmp_skb);
goto free_neigh;
}
send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
if (send_status == NET_XMIT_SUCCESS) {
/* count the sent packet */
switch (packet_subtype) {
case BATADV_P_DAT_DHT_GET:
batadv_inc_counter(bat_priv,
BATADV_CNT_DAT_GET_TX);
break;
case BATADV_P_DAT_DHT_PUT:
batadv_inc_counter(bat_priv,
BATADV_CNT_DAT_PUT_TX);
break;
}
/* packet sent to a candidate: return true */
ret = true;
}
free_neigh:
batadv_neigh_node_put(neigh_node);
free_orig:
batadv_orig_node_put(cand[i].orig_node);
}
kfree(cand);
return ret;
}
/**
* batadv_dat_tvlv_container_update() - update the dat tvlv container after dat
* setting change
* @bat_priv: the bat priv with all the soft interface information
*/
static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
{
char dat_mode;
dat_mode = atomic_read(&bat_priv->distributed_arp_table);
switch (dat_mode) {
case 0:
batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
break;
case 1:
batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
NULL, 0);
break;
}
}
/**
* batadv_dat_status_update() - update the dat tvlv container after dat
* setting change
* @net_dev: the soft interface net device
*/
void batadv_dat_status_update(struct net_device *net_dev)
{
struct batadv_priv *bat_priv = netdev_priv(net_dev);
batadv_dat_tvlv_container_update(bat_priv);
}
/**
* batadv_dat_tvlv_ogm_handler_v1() - process incoming dat tvlv container
* @bat_priv: the bat priv with all the soft interface information
* @orig: the orig_node of the ogm
* @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
* @tvlv_value: tvlv buffer containing the gateway data
* @tvlv_value_len: tvlv buffer length
*/
static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig,
u8 flags,
void *tvlv_value, u16 tvlv_value_len)
{
if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
else
set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
}
/**
* batadv_dat_hash_free() - free the local DAT hash table
* @bat_priv: the bat priv with all the soft interface information
*/
static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
{
if (!bat_priv->dat.hash)
return;
__batadv_dat_purge(bat_priv, NULL);
batadv_hash_destroy(bat_priv->dat.hash);
bat_priv->dat.hash = NULL;
}
/**
* batadv_dat_init() - initialise the DAT internals
* @bat_priv: the bat priv with all the soft interface information
*
* Return: 0 in case of success, a negative error code otherwise
*/
int batadv_dat_init(struct batadv_priv *bat_priv)
{
if (bat_priv->dat.hash)
return 0;
bat_priv->dat.hash = batadv_hash_new(1024);
if (!bat_priv->dat.hash)
return -ENOMEM;
INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
batadv_dat_start_timer(bat_priv);
batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
NULL, NULL, BATADV_TVLV_DAT, 1,
BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
batadv_dat_tvlv_container_update(bat_priv);
return 0;
}
/**
* batadv_dat_free() - free the DAT internals
* @bat_priv: the bat priv with all the soft interface information
*/
void batadv_dat_free(struct batadv_priv *bat_priv)
{
batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
cancel_delayed_work_sync(&bat_priv->dat.work);
batadv_dat_hash_free(bat_priv);
}
/**
* batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
* netlink socket
* @msg: buffer for the message
* @portid: netlink port
* @cb: Control block containing additional options
* @dat_entry: entry to dump
*
* Return: 0 or error code.
*/
static int
batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
struct netlink_callback *cb,
struct batadv_dat_entry *dat_entry)
{
int msecs;
void *hdr;
hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
&batadv_netlink_family, NLM_F_MULTI,
BATADV_CMD_GET_DAT_CACHE);
if (!hdr)
return -ENOBUFS;
genl_dump_check_consistent(cb, hdr);
msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
dat_entry->ip) ||
nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
dat_entry->mac_addr) ||
nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
genlmsg_cancel(msg, hdr);
return -EMSGSIZE;
}
genlmsg_end(msg, hdr);
return 0;
}
/**
* batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
* a netlink socket
* @msg: buffer for the message
* @portid: netlink port
* @cb: Control block containing additional options
* @hash: hash to dump
* @bucket: bucket index to dump
* @idx_skip: How many entries to skip
*
* Return: 0 or error code.
*/
static int
batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
struct netlink_callback *cb,
struct batadv_hashtable *hash, unsigned int bucket,
int *idx_skip)
{
struct batadv_dat_entry *dat_entry;
int idx = 0;
spin_lock_bh(&hash->list_locks[bucket]);
cb->seq = atomic_read(&hash->generation) << 1 | 1;
hlist_for_each_entry(dat_entry, &hash->table[bucket], hash_entry) {
if (idx < *idx_skip)
goto skip;
if (batadv_dat_cache_dump_entry(msg, portid, cb, dat_entry)) {
spin_unlock_bh(&hash->list_locks[bucket]);
*idx_skip = idx;
return -EMSGSIZE;
}
skip:
idx++;
}
spin_unlock_bh(&hash->list_locks[bucket]);
return 0;
}
/**
* batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
* @msg: buffer for the message
* @cb: callback structure containing arguments
*
* Return: message length.
*/
int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
{
struct batadv_hard_iface *primary_if = NULL;
int portid = NETLINK_CB(cb->skb).portid;
struct net *net = sock_net(cb->skb->sk);
struct net_device *soft_iface;
struct batadv_hashtable *hash;
struct batadv_priv *bat_priv;
int bucket = cb->args[0];
int idx = cb->args[1];
int ifindex;
int ret = 0;
ifindex = batadv_netlink_get_ifindex(cb->nlh,
BATADV_ATTR_MESH_IFINDEX);
if (!ifindex)
return -EINVAL;
soft_iface = dev_get_by_index(net, ifindex);
if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
ret = -ENODEV;
goto out;
}
bat_priv = netdev_priv(soft_iface);
hash = bat_priv->dat.hash;
primary_if = batadv_primary_if_get_selected(bat_priv);
if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
ret = -ENOENT;
goto out;
}
while (bucket < hash->size) {
if (batadv_dat_cache_dump_bucket(msg, portid, cb, hash, bucket,
&idx))
break;
bucket++;
idx = 0;
}
cb->args[0] = bucket;
cb->args[1] = idx;
ret = msg->len;
out:
batadv_hardif_put(primary_if);
dev_put(soft_iface);
return ret;
}
/**
* batadv_arp_get_type() - parse an ARP packet and gets the type
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to analyse
* @hdr_size: size of the possible header before the ARP packet in the skb
*
* Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
*/
static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
struct sk_buff *skb, int hdr_size)
{
struct arphdr *arphdr;
struct ethhdr *ethhdr;
__be32 ip_src, ip_dst;
u8 *hw_src, *hw_dst;
u16 type = 0;
/* pull the ethernet header */
if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
goto out;
ethhdr = (struct ethhdr *)(skb->data + hdr_size);
if (ethhdr->h_proto != htons(ETH_P_ARP))
goto out;
/* pull the ARP payload */
if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
arp_hdr_len(skb->dev))))
goto out;
arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
/* check whether the ARP packet carries a valid IP information */
if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
goto out;
if (arphdr->ar_pro != htons(ETH_P_IP))
goto out;
if (arphdr->ar_hln != ETH_ALEN)
goto out;
if (arphdr->ar_pln != 4)
goto out;
/* Check for bad reply/request. If the ARP message is not sane, DAT
* will simply ignore it
*/
ip_src = batadv_arp_ip_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
goto out;
hw_src = batadv_arp_hw_src(skb, hdr_size);
if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
goto out;
/* don't care about the destination MAC address in ARP requests */
if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
hw_dst = batadv_arp_hw_dst(skb, hdr_size);
if (is_zero_ether_addr(hw_dst) ||
is_multicast_ether_addr(hw_dst))
goto out;
}
type = ntohs(arphdr->ar_op);
out:
return type;
}
/**
* batadv_dat_get_vid() - extract the VLAN identifier from skb if any
* @skb: the buffer containing the packet to extract the VID from
* @hdr_size: the size of the batman-adv header encapsulating the packet
*
* Return: If the packet embedded in the skb is vlan tagged this function
* returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
* is returned.
*/
static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
{
unsigned short vid;
vid = batadv_get_vid(skb, *hdr_size);
/* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
* If the header contained in the packet is a VLAN one (which is longer)
* hdr_size is updated so that the functions will still skip the
* correct amount of bytes.
*/
if (vid & BATADV_VLAN_HAS_TAG)
*hdr_size += VLAN_HLEN;
return vid;
}
/**
* batadv_dat_arp_create_reply() - create an ARP Reply
* @bat_priv: the bat priv with all the soft interface information
* @ip_src: ARP sender IP
* @ip_dst: ARP target IP
* @hw_src: Ethernet source and ARP sender MAC
* @hw_dst: Ethernet destination and ARP target MAC
* @vid: VLAN identifier (optional, set to zero otherwise)
*
* Creates an ARP Reply from the given values, optionally encapsulated in a
* VLAN header.
*
* Return: An skb containing an ARP Reply.
*/
static struct sk_buff *
batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
__be32 ip_dst, u8 *hw_src, u8 *hw_dst,
unsigned short vid)
{
struct sk_buff *skb;
skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->soft_iface,
ip_src, hw_dst, hw_src, hw_dst);
if (!skb)
return NULL;
skb_reset_mac_header(skb);
if (vid & BATADV_VLAN_HAS_TAG)
skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
vid & VLAN_VID_MASK);
return skb;
}
/**
* batadv_dat_snoop_outgoing_arp_request() - snoop the ARP request and try to
* answer using DAT
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to check
*
* Return: true if the message has been sent to the dht candidates, false
* otherwise. In case of a positive return value the message has to be enqueued
* to permit the fallback.
*/
bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
struct sk_buff *skb)
{
u16 type = 0;
__be32 ip_dst, ip_src;
u8 *hw_src;
bool ret = false;
struct batadv_dat_entry *dat_entry = NULL;
struct sk_buff *skb_new;
struct net_device *soft_iface = bat_priv->soft_iface;
int hdr_size = 0;
unsigned short vid;
if (!atomic_read(&bat_priv->distributed_arp_table))
goto out;
vid = batadv_dat_get_vid(skb, &hdr_size);
type = batadv_arp_get_type(bat_priv, skb, hdr_size);
/* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
* message to the selected DHT candidates
*/
if (type != ARPOP_REQUEST)
goto out;
batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
ip_src = batadv_arp_ip_src(skb, hdr_size);
hw_src = batadv_arp_hw_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
if (dat_entry) {
/* If the ARP request is destined for a local client the local
* client will answer itself. DAT would only generate a
* duplicate packet.
*
* Moreover, if the soft-interface is enslaved into a bridge, an
* additional DAT answer may trigger kernel warnings about
* a packet coming from the wrong port.
*/
if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
ret = true;
goto out;
}
/* If BLA is enabled, only send ARP replies if we have claimed
* the destination for the ARP request or if no one else of
* the backbone gws belonging to our backbone has claimed the
* destination.
*/
if (!batadv_bla_check_claim(bat_priv,
dat_entry->mac_addr, vid)) {
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Device %pM claimed by another backbone gw. Don't send ARP reply!",
dat_entry->mac_addr);
ret = true;
goto out;
}
skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
dat_entry->mac_addr,
hw_src, vid);
if (!skb_new)
goto out;
skb_new->protocol = eth_type_trans(skb_new, soft_iface);
batadv_inc_counter(bat_priv, BATADV_CNT_RX);
batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
skb->len + ETH_HLEN + hdr_size);
netif_rx(skb_new);
batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
ret = true;
} else {
/* Send the request to the DHT */
ret = batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
BATADV_P_DAT_DHT_GET);
}
out:
batadv_dat_entry_put(dat_entry);
return ret;
}
/**
* batadv_dat_snoop_incoming_arp_request() - snoop the ARP request and try to
* answer using the local DAT storage
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to check
* @hdr_size: size of the encapsulation header
*
* Return: true if the request has been answered, false otherwise.
*/
bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
struct sk_buff *skb, int hdr_size)
{
u16 type;
__be32 ip_src, ip_dst;
u8 *hw_src;
struct sk_buff *skb_new;
struct batadv_dat_entry *dat_entry = NULL;
bool ret = false;
unsigned short vid;
int err;
if (!atomic_read(&bat_priv->distributed_arp_table))
goto out;
vid = batadv_dat_get_vid(skb, &hdr_size);
type = batadv_arp_get_type(bat_priv, skb, hdr_size);
if (type != ARPOP_REQUEST)
goto out;
hw_src = batadv_arp_hw_src(skb, hdr_size);
ip_src = batadv_arp_ip_src(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
if (!dat_entry)
goto out;
skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
dat_entry->mac_addr, hw_src, vid);
if (!skb_new)
goto out;
/* To preserve backwards compatibility, the node has choose the outgoing
* format based on the incoming request packet type. The assumption is
* that a node not using the 4addr packet format doesn't support it.
*/
if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
BATADV_P_DAT_CACHE_REPLY,
NULL, vid);
else
err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
if (err != NET_XMIT_DROP) {
batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
ret = true;
}
out:
batadv_dat_entry_put(dat_entry);
if (ret)
kfree_skb(skb);
return ret;
}
/**
* batadv_dat_snoop_outgoing_arp_reply() - snoop the ARP reply and fill the DHT
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to check
*/
void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
struct sk_buff *skb)
{
u16 type;
__be32 ip_src, ip_dst;
u8 *hw_src, *hw_dst;
int hdr_size = 0;
unsigned short vid;
if (!atomic_read(&bat_priv->distributed_arp_table))
return;
vid = batadv_dat_get_vid(skb, &hdr_size);
type = batadv_arp_get_type(bat_priv, skb, hdr_size);
if (type != ARPOP_REPLY)
return;
batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
hw_src = batadv_arp_hw_src(skb, hdr_size);
ip_src = batadv_arp_ip_src(skb, hdr_size);
hw_dst = batadv_arp_hw_dst(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
/* Send the ARP reply to the candidates for both the IP addresses that
* the node obtained from the ARP reply
*/
batadv_dat_forward_data(bat_priv, skb, ip_src, vid,
BATADV_P_DAT_DHT_PUT);
batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
BATADV_P_DAT_DHT_PUT);
}
/**
* batadv_dat_snoop_incoming_arp_reply() - snoop the ARP reply and fill the
* local DAT storage only
* @bat_priv: the bat priv with all the soft interface information
* @skb: packet to check
* @hdr_size: size of the encapsulation header
*
* Return: true if the packet was snooped and consumed by DAT. False if the
* packet has to be delivered to the interface
*/
bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
struct sk_buff *skb, int hdr_size)
{
struct batadv_dat_entry *dat_entry = NULL;
u16 type;
__be32 ip_src, ip_dst;
u8 *hw_src, *hw_dst;
bool dropped = false;
unsigned short vid;
if (!atomic_read(&bat_priv->distributed_arp_table))
goto out;
vid = batadv_dat_get_vid(skb, &hdr_size);
type = batadv_arp_get_type(bat_priv, skb, hdr_size);
if (type != ARPOP_REPLY)
goto out;
batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
hw_src = batadv_arp_hw_src(skb, hdr_size);
ip_src = batadv_arp_ip_src(skb, hdr_size);
hw_dst = batadv_arp_hw_dst(skb, hdr_size);
ip_dst = batadv_arp_ip_dst(skb, hdr_size);
/* If ip_dst is already in cache and has the right mac address,
* drop this frame if this ARP reply is destined for us because it's
* most probably an ARP reply generated by another node of the DHT.
* We have most probably received already a reply earlier. Delivering
* this frame would lead to doubled receive of an ARP reply.
*/
dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
hw_src, &ip_src, hw_dst, &ip_dst,
dat_entry->mac_addr, &dat_entry->ip);
dropped = true;
}
/* Update our internal cache with both the IP addresses the node got
* within the ARP reply
*/
batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
if (dropped)
goto out;
/* If BLA is enabled, only forward ARP replies if we have claimed the
* source of the ARP reply or if no one else of the same backbone has
* already claimed that client. This prevents that different gateways
* to the same backbone all forward the ARP reply leading to multiple
* replies in the backbone.
*/
if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Device %pM claimed by another backbone gw. Drop ARP reply.\n",
hw_src);
dropped = true;
goto out;
}
/* if this REPLY is directed to a client of mine, let's deliver the
* packet to the interface
*/
dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
/* if this REPLY is sent on behalf of a client of mine, let's drop the
* packet because the client will reply by itself
*/
dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
out:
if (dropped)
kfree_skb(skb);
batadv_dat_entry_put(dat_entry);
/* if dropped == false -> deliver to the interface */
return dropped;
}
/**
* batadv_dat_check_dhcp_ipudp() - check skb for IP+UDP headers valid for DHCP
* @skb: the packet to check
* @ip_src: a buffer to store the IPv4 source address in
*
* Checks whether the given skb has an IP and UDP header valid for a DHCP
* message from a DHCP server. And if so, stores the IPv4 source address in
* the provided buffer.
*
* Return: True if valid, false otherwise.
*/
static bool
batadv_dat_check_dhcp_ipudp(struct sk_buff *skb, __be32 *ip_src)
{
unsigned int offset = skb_network_offset(skb);
struct udphdr *udphdr, _udphdr;
struct iphdr *iphdr, _iphdr;
iphdr = skb_header_pointer(skb, offset, sizeof(_iphdr), &_iphdr);
if (!iphdr || iphdr->version != 4 || iphdr->ihl * 4 < sizeof(_iphdr))
return false;
if (iphdr->protocol != IPPROTO_UDP)
return false;
offset += iphdr->ihl * 4;
skb_set_transport_header(skb, offset);
udphdr = skb_header_pointer(skb, offset, sizeof(_udphdr), &_udphdr);
if (!udphdr || udphdr->source != htons(67))
return false;
*ip_src = get_unaligned(&iphdr->saddr);
return true;
}
/**
* batadv_dat_check_dhcp() - examine packet for valid DHCP message
* @skb: the packet to check
* @proto: ethernet protocol hint (behind a potential vlan)
* @ip_src: a buffer to store the IPv4 source address in
*
* Checks whether the given skb is a valid DHCP packet. And if so, stores the
* IPv4 source address in the provided buffer.
*
* Caller needs to ensure that the skb network header is set correctly.
*
* Return: If skb is a valid DHCP packet, then returns its op code
* (e.g. BOOTREPLY vs. BOOTREQUEST). Otherwise returns -EINVAL.
*/
static int
batadv_dat_check_dhcp(struct sk_buff *skb, __be16 proto, __be32 *ip_src)
{
__be32 *magic, _magic;
unsigned int offset;
struct {
__u8 op;
__u8 htype;
__u8 hlen;
__u8 hops;
} *dhcp_h, _dhcp_h;
if (proto != htons(ETH_P_IP))
return -EINVAL;
if (!batadv_dat_check_dhcp_ipudp(skb, ip_src))
return -EINVAL;
offset = skb_transport_offset(skb) + sizeof(struct udphdr);
if (skb->len < offset + sizeof(struct batadv_dhcp_packet))
return -EINVAL;
dhcp_h = skb_header_pointer(skb, offset, sizeof(_dhcp_h), &_dhcp_h);
if (!dhcp_h || dhcp_h->htype != BATADV_HTYPE_ETHERNET ||
dhcp_h->hlen != ETH_ALEN)
return -EINVAL;
offset += offsetof(struct batadv_dhcp_packet, magic);
magic = skb_header_pointer(skb, offset, sizeof(_magic), &_magic);
if (!magic || get_unaligned(magic) != htonl(BATADV_DHCP_MAGIC))
return -EINVAL;
return dhcp_h->op;
}
/**
* batadv_dat_get_dhcp_message_type() - get message type of a DHCP packet
* @skb: the DHCP packet to parse
*
* Iterates over the DHCP options of the given DHCP packet to find a
* DHCP Message Type option and parse it.
*
* Caller needs to ensure that the given skb is a valid DHCP packet and
* that the skb transport header is set correctly.
*
* Return: The found DHCP message type value, if found. -EINVAL otherwise.
*/
static int batadv_dat_get_dhcp_message_type(struct sk_buff *skb)
{
unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
u8 *type, _type;
struct {
u8 type;
u8 len;
} *tl, _tl;
offset += sizeof(struct batadv_dhcp_packet);
while ((tl = skb_header_pointer(skb, offset, sizeof(_tl), &_tl))) {
if (tl->type == BATADV_DHCP_OPT_MSG_TYPE)
break;
if (tl->type == BATADV_DHCP_OPT_END)
break;
if (tl->type == BATADV_DHCP_OPT_PAD)
offset++;
else
offset += tl->len + sizeof(_tl);
}
/* Option Overload Code not supported */
if (!tl || tl->type != BATADV_DHCP_OPT_MSG_TYPE ||
tl->len != sizeof(_type))
return -EINVAL;
offset += sizeof(_tl);
type = skb_header_pointer(skb, offset, sizeof(_type), &_type);
if (!type)
return -EINVAL;
return *type;
}
/**
* batadv_dat_dhcp_get_yiaddr() - get yiaddr from a DHCP packet
* @skb: the DHCP packet to parse
* @buf: a buffer to store the yiaddr in
*
* Caller needs to ensure that the given skb is a valid DHCP packet and
* that the skb transport header is set correctly.
*
* Return: True on success, false otherwise.
*/
static bool batadv_dat_dhcp_get_yiaddr(struct sk_buff *skb, __be32 *buf)
{
unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
__be32 *yiaddr;
offset += offsetof(struct batadv_dhcp_packet, yiaddr);
yiaddr = skb_header_pointer(skb, offset, BATADV_DHCP_YIADDR_LEN, buf);
if (!yiaddr)
return false;
if (yiaddr != buf)
*buf = get_unaligned(yiaddr);
return true;
}
/**
* batadv_dat_get_dhcp_chaddr() - get chaddr from a DHCP packet
* @skb: the DHCP packet to parse
* @buf: a buffer to store the chaddr in
*
* Caller needs to ensure that the given skb is a valid DHCP packet and
* that the skb transport header is set correctly.
*
* Return: True on success, false otherwise
*/
static bool batadv_dat_get_dhcp_chaddr(struct sk_buff *skb, u8 *buf)
{
unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
u8 *chaddr;
offset += offsetof(struct batadv_dhcp_packet, chaddr);
chaddr = skb_header_pointer(skb, offset, BATADV_DHCP_CHADDR_LEN, buf);
if (!chaddr)
return false;
if (chaddr != buf)
memcpy(buf, chaddr, BATADV_DHCP_CHADDR_LEN);
return true;
}
/**
* batadv_dat_put_dhcp() - puts addresses from a DHCP packet into the DHT and
* DAT cache
* @bat_priv: the bat priv with all the soft interface information
* @chaddr: the DHCP client MAC address
* @yiaddr: the DHCP client IP address
* @hw_dst: the DHCP server MAC address
* @ip_dst: the DHCP server IP address
* @vid: VLAN identifier
*
* Adds given MAC/IP pairs to the local DAT cache and propagates them further
* into the DHT.
*
* For the DHT propagation, client MAC + IP will appear as the ARP Reply
* transmitter (and hw_dst/ip_dst as the target).
*/
static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
__be32 yiaddr, u8 *hw_dst, __be32 ip_dst,
unsigned short vid)
{
struct sk_buff *skb;
skb = batadv_dat_arp_create_reply(bat_priv, yiaddr, ip_dst, chaddr,
hw_dst, vid);
if (!skb)
return;
skb_set_network_header(skb, ETH_HLEN);
batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
batadv_dat_forward_data(bat_priv, skb, yiaddr, vid,
BATADV_P_DAT_DHT_PUT);
batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
BATADV_P_DAT_DHT_PUT);
consume_skb(skb);
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Snooped from outgoing DHCPACK (server address): %pI4, %pM (vid: %i)\n",
&ip_dst, hw_dst, batadv_print_vid(vid));
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Snooped from outgoing DHCPACK (client address): %pI4, %pM (vid: %i)\n",
&yiaddr, chaddr, batadv_print_vid(vid));
}
/**
* batadv_dat_check_dhcp_ack() - examine packet for valid DHCP message
* @skb: the packet to check
* @proto: ethernet protocol hint (behind a potential vlan)
* @ip_src: a buffer to store the IPv4 source address in
* @chaddr: a buffer to store the DHCP Client Hardware Address in
* @yiaddr: a buffer to store the DHCP Your IP Address in
*
* Checks whether the given skb is a valid DHCPACK. And if so, stores the
* IPv4 server source address (ip_src), client MAC address (chaddr) and client
* IPv4 address (yiaddr) in the provided buffers.
*
* Caller needs to ensure that the skb network header is set correctly.
*
* Return: True if the skb is a valid DHCPACK. False otherwise.
*/
static bool
batadv_dat_check_dhcp_ack(struct sk_buff *skb, __be16 proto, __be32 *ip_src,
u8 *chaddr, __be32 *yiaddr)
{
int type;
type = batadv_dat_check_dhcp(skb, proto, ip_src);
if (type != BATADV_BOOTREPLY)
return false;
type = batadv_dat_get_dhcp_message_type(skb);
if (type != BATADV_DHCPACK)
return false;
if (!batadv_dat_dhcp_get_yiaddr(skb, yiaddr))
return false;
if (!batadv_dat_get_dhcp_chaddr(skb, chaddr))
return false;
return true;
}
/**
* batadv_dat_snoop_outgoing_dhcp_ack() - snoop DHCPACK and fill DAT with it
* @bat_priv: the bat priv with all the soft interface information
* @skb: the packet to snoop
* @proto: ethernet protocol hint (behind a potential vlan)
* @vid: VLAN identifier
*
* This function first checks whether the given skb is a valid DHCPACK. If
* so then its source MAC and IP as well as its DHCP Client Hardware Address
* field and DHCP Your IP Address field are added to the local DAT cache and
* propagated into the DHT.
*
* Caller needs to ensure that the skb mac and network headers are set
* correctly.
*/
void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
struct sk_buff *skb,
__be16 proto,
unsigned short vid)
{
u8 chaddr[BATADV_DHCP_CHADDR_LEN];
__be32 ip_src, yiaddr;
if (!atomic_read(&bat_priv->distributed_arp_table))
return;
if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
return;
batadv_dat_put_dhcp(bat_priv, chaddr, yiaddr, eth_hdr(skb)->h_source,
ip_src, vid);
}
/**
* batadv_dat_snoop_incoming_dhcp_ack() - snoop DHCPACK and fill DAT cache
* @bat_priv: the bat priv with all the soft interface information
* @skb: the packet to snoop
* @hdr_size: header size, up to the tail of the batman-adv header
*
* This function first checks whether the given skb is a valid DHCPACK. If
* so then its source MAC and IP as well as its DHCP Client Hardware Address
* field and DHCP Your IP Address field are added to the local DAT cache.
*/
void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
struct sk_buff *skb, int hdr_size)
{
u8 chaddr[BATADV_DHCP_CHADDR_LEN];
struct ethhdr *ethhdr;
__be32 ip_src, yiaddr;
unsigned short vid;
__be16 proto;
u8 *hw_src;
if (!atomic_read(&bat_priv->distributed_arp_table))
return;
if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
return;
ethhdr = (struct ethhdr *)(skb->data + hdr_size);
skb_set_network_header(skb, hdr_size + ETH_HLEN);
proto = ethhdr->h_proto;
if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
return;
hw_src = ethhdr->h_source;
vid = batadv_dat_get_vid(skb, &hdr_size);
batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
&ip_src, hw_src, batadv_print_vid(vid));
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"Snooped from incoming DHCPACK (client address): %pI4, %pM (vid: %i)\n",
&yiaddr, chaddr, batadv_print_vid(vid));
}
/**
* batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
* dropped (because the node has already obtained the reply via DAT) or not
* @bat_priv: the bat priv with all the soft interface information
* @forw_packet: the broadcast packet
*
* Return: true if the node can drop the packet, false otherwise.
*/
bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
struct batadv_forw_packet *forw_packet)
{
u16 type;
__be32 ip_dst;
struct batadv_dat_entry *dat_entry = NULL;
bool ret = false;
int hdr_size = sizeof(struct batadv_bcast_packet);
unsigned short vid;
if (!atomic_read(&bat_priv->distributed_arp_table))
goto out;
/* If this packet is an ARP_REQUEST and the node already has the
* information that it is going to ask, then the packet can be dropped
*/
if (batadv_forw_packet_is_rebroadcast(forw_packet))
goto out;
vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
if (type != ARPOP_REQUEST)
goto out;
ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
/* check if the node already got this entry */
if (!dat_entry) {
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"ARP Request for %pI4: fallback\n", &ip_dst);
goto out;
}
batadv_dbg(BATADV_DBG_DAT, bat_priv,
"ARP Request for %pI4: fallback prevented\n", &ip_dst);
ret = true;
out:
batadv_dat_entry_put(dat_entry);
return ret;
}
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