linux_dsm_epyc7002/net/batman-adv/gateway_client.c
Sven Eckelmann dff9bc42ab batman-adv: Prevent duplicated gateway_node entry
The function batadv_gw_node_add is responsible for adding new gw_node to
the gateway_list. It is expecting that the caller already checked that
there is not already an entry with the same key or not.

But the lock for the list is only held when the list is really modified.
This could lead to duplicated entries because another context could create
an entry with the same key between the check and the list manipulation.

The check and the manipulation of the list must therefore be in the same
locked code section.

Fixes: c6c8fea297 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
2018-09-06 13:55:20 +02:00

843 lines
23 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2009-2018 B.A.T.M.A.N. contributors:
*
* Marek Lindner
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "gateway_client.h"
#include "main.h"
#include <linux/atomic.h>
#include <linux/byteorder/generic.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/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/udp.h>
#include <net/sock.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>
#include "gateway_common.h"
#include "hard-interface.h"
#include "log.h"
#include "netlink.h"
#include "originator.h"
#include "routing.h"
#include "soft-interface.h"
#include "sysfs.h"
#include "translation-table.h"
/* These are the offsets of the "hw type" and "hw address length" in the dhcp
* packet starting at the beginning of the dhcp header
*/
#define BATADV_DHCP_HTYPE_OFFSET 1
#define BATADV_DHCP_HLEN_OFFSET 2
/* Value of htype representing Ethernet */
#define BATADV_DHCP_HTYPE_ETHERNET 0x01
/* This is the offset of the "chaddr" field in the dhcp packet starting at the
* beginning of the dhcp header
*/
#define BATADV_DHCP_CHADDR_OFFSET 28
/**
* batadv_gw_node_release() - release gw_node from lists and queue for free
* after rcu grace period
* @ref: kref pointer of the gw_node
*/
static void batadv_gw_node_release(struct kref *ref)
{
struct batadv_gw_node *gw_node;
gw_node = container_of(ref, struct batadv_gw_node, refcount);
batadv_orig_node_put(gw_node->orig_node);
kfree_rcu(gw_node, rcu);
}
/**
* batadv_gw_node_put() - decrement the gw_node refcounter and possibly release
* it
* @gw_node: gateway node to free
*/
void batadv_gw_node_put(struct batadv_gw_node *gw_node)
{
kref_put(&gw_node->refcount, batadv_gw_node_release);
}
/**
* batadv_gw_get_selected_gw_node() - Get currently selected gateway
* @bat_priv: the bat priv with all the soft interface information
*
* Return: selected gateway (with increased refcnt), NULL on errors
*/
struct batadv_gw_node *
batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
{
struct batadv_gw_node *gw_node;
rcu_read_lock();
gw_node = rcu_dereference(bat_priv->gw.curr_gw);
if (!gw_node)
goto out;
if (!kref_get_unless_zero(&gw_node->refcount))
gw_node = NULL;
out:
rcu_read_unlock();
return gw_node;
}
/**
* batadv_gw_get_selected_orig() - Get originator of currently selected gateway
* @bat_priv: the bat priv with all the soft interface information
*
* Return: orig_node of selected gateway (with increased refcnt), NULL on errors
*/
struct batadv_orig_node *
batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
{
struct batadv_gw_node *gw_node;
struct batadv_orig_node *orig_node = NULL;
gw_node = batadv_gw_get_selected_gw_node(bat_priv);
if (!gw_node)
goto out;
rcu_read_lock();
orig_node = gw_node->orig_node;
if (!orig_node)
goto unlock;
if (!kref_get_unless_zero(&orig_node->refcount))
orig_node = NULL;
unlock:
rcu_read_unlock();
out:
if (gw_node)
batadv_gw_node_put(gw_node);
return orig_node;
}
static void batadv_gw_select(struct batadv_priv *bat_priv,
struct batadv_gw_node *new_gw_node)
{
struct batadv_gw_node *curr_gw_node;
spin_lock_bh(&bat_priv->gw.list_lock);
if (new_gw_node)
kref_get(&new_gw_node->refcount);
curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
if (curr_gw_node)
batadv_gw_node_put(curr_gw_node);
spin_unlock_bh(&bat_priv->gw.list_lock);
}
/**
* batadv_gw_reselect() - force a gateway reselection
* @bat_priv: the bat priv with all the soft interface information
*
* Set a flag to remind the GW component to perform a new gateway reselection.
* However this function does not ensure that the current gateway is going to be
* deselected. The reselection mechanism may elect the same gateway once again.
*
* This means that invoking batadv_gw_reselect() does not guarantee a gateway
* change and therefore a uevent is not necessarily expected.
*/
void batadv_gw_reselect(struct batadv_priv *bat_priv)
{
atomic_set(&bat_priv->gw.reselect, 1);
}
/**
* batadv_gw_check_client_stop() - check if client mode has been switched off
* @bat_priv: the bat priv with all the soft interface information
*
* This function assumes the caller has checked that the gw state *is actually
* changing*. This function is not supposed to be called when there is no state
* change.
*/
void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
{
struct batadv_gw_node *curr_gw;
if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
return;
curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
if (!curr_gw)
return;
/* deselect the current gateway so that next time that client mode is
* enabled a proper GW_ADD event can be sent
*/
batadv_gw_select(bat_priv, NULL);
/* if batman-adv is switching the gw client mode off and a gateway was
* already selected, send a DEL uevent
*/
batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
batadv_gw_node_put(curr_gw);
}
/**
* batadv_gw_election() - Elect the best gateway
* @bat_priv: the bat priv with all the soft interface information
*/
void batadv_gw_election(struct batadv_priv *bat_priv)
{
struct batadv_gw_node *curr_gw = NULL;
struct batadv_gw_node *next_gw = NULL;
struct batadv_neigh_node *router = NULL;
struct batadv_neigh_ifinfo *router_ifinfo = NULL;
char gw_addr[18] = { '\0' };
if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
goto out;
if (!bat_priv->algo_ops->gw.get_best_gw_node)
goto out;
curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
goto out;
/* if gw.reselect is set to 1 it means that a previous call to
* gw.is_eligible() said that we have a new best GW, therefore it can
* now be picked from the list and selected
*/
next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv);
if (curr_gw == next_gw)
goto out;
if (next_gw) {
sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
router = batadv_orig_router_get(next_gw->orig_node,
BATADV_IF_DEFAULT);
if (!router) {
batadv_gw_reselect(bat_priv);
goto out;
}
router_ifinfo = batadv_neigh_ifinfo_get(router,
BATADV_IF_DEFAULT);
if (!router_ifinfo) {
batadv_gw_reselect(bat_priv);
goto out;
}
}
if (curr_gw && !next_gw) {
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Removing selected gateway - no gateway in range\n");
batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
NULL);
} else if (!curr_gw && next_gw) {
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
next_gw->orig_node->orig,
next_gw->bandwidth_down / 10,
next_gw->bandwidth_down % 10,
next_gw->bandwidth_up / 10,
next_gw->bandwidth_up % 10,
router_ifinfo->bat_iv.tq_avg);
batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
gw_addr);
} else {
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
next_gw->orig_node->orig,
next_gw->bandwidth_down / 10,
next_gw->bandwidth_down % 10,
next_gw->bandwidth_up / 10,
next_gw->bandwidth_up % 10,
router_ifinfo->bat_iv.tq_avg);
batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
gw_addr);
}
batadv_gw_select(bat_priv, next_gw);
out:
if (curr_gw)
batadv_gw_node_put(curr_gw);
if (next_gw)
batadv_gw_node_put(next_gw);
if (router)
batadv_neigh_node_put(router);
if (router_ifinfo)
batadv_neigh_ifinfo_put(router_ifinfo);
}
/**
* batadv_gw_check_election() - Elect orig node as best gateway when eligible
* @bat_priv: the bat priv with all the soft interface information
* @orig_node: orig node which is to be checked
*/
void batadv_gw_check_election(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node)
{
struct batadv_orig_node *curr_gw_orig;
/* abort immediately if the routing algorithm does not support gateway
* election
*/
if (!bat_priv->algo_ops->gw.is_eligible)
return;
curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
if (!curr_gw_orig)
goto reselect;
/* this node already is the gateway */
if (curr_gw_orig == orig_node)
goto out;
if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig,
orig_node))
goto out;
reselect:
batadv_gw_reselect(bat_priv);
out:
if (curr_gw_orig)
batadv_orig_node_put(curr_gw_orig);
}
/**
* batadv_gw_node_add() - add gateway node to list of available gateways
* @bat_priv: the bat priv with all the soft interface information
* @orig_node: originator announcing gateway capabilities
* @gateway: announced bandwidth information
*
* Has to be called with the appropriate locks being acquired
* (gw.list_lock).
*/
static void batadv_gw_node_add(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node,
struct batadv_tvlv_gateway_data *gateway)
{
struct batadv_gw_node *gw_node;
lockdep_assert_held(&bat_priv->gw.list_lock);
if (gateway->bandwidth_down == 0)
return;
gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
if (!gw_node)
return;
kref_init(&gw_node->refcount);
INIT_HLIST_NODE(&gw_node->list);
kref_get(&orig_node->refcount);
gw_node->orig_node = orig_node;
gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
kref_get(&gw_node->refcount);
hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
orig_node->orig,
ntohl(gateway->bandwidth_down) / 10,
ntohl(gateway->bandwidth_down) % 10,
ntohl(gateway->bandwidth_up) / 10,
ntohl(gateway->bandwidth_up) % 10);
/* don't return reference to new gw_node */
batadv_gw_node_put(gw_node);
}
/**
* batadv_gw_node_get() - retrieve gateway node from list of available gateways
* @bat_priv: the bat priv with all the soft interface information
* @orig_node: originator announcing gateway capabilities
*
* Return: gateway node if found or NULL otherwise.
*/
struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node)
{
struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
rcu_read_lock();
hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list,
list) {
if (gw_node_tmp->orig_node != orig_node)
continue;
if (!kref_get_unless_zero(&gw_node_tmp->refcount))
continue;
gw_node = gw_node_tmp;
break;
}
rcu_read_unlock();
return gw_node;
}
/**
* batadv_gw_node_update() - update list of available gateways with changed
* bandwidth information
* @bat_priv: the bat priv with all the soft interface information
* @orig_node: originator announcing gateway capabilities
* @gateway: announced bandwidth information
*/
void batadv_gw_node_update(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node,
struct batadv_tvlv_gateway_data *gateway)
{
struct batadv_gw_node *gw_node, *curr_gw = NULL;
spin_lock_bh(&bat_priv->gw.list_lock);
gw_node = batadv_gw_node_get(bat_priv, orig_node);
if (!gw_node) {
batadv_gw_node_add(bat_priv, orig_node, gateway);
spin_unlock_bh(&bat_priv->gw.list_lock);
goto out;
}
spin_unlock_bh(&bat_priv->gw.list_lock);
if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) &&
gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))
goto out;
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
orig_node->orig,
gw_node->bandwidth_down / 10,
gw_node->bandwidth_down % 10,
gw_node->bandwidth_up / 10,
gw_node->bandwidth_up % 10,
ntohl(gateway->bandwidth_down) / 10,
ntohl(gateway->bandwidth_down) % 10,
ntohl(gateway->bandwidth_up) / 10,
ntohl(gateway->bandwidth_up) % 10);
gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
if (ntohl(gateway->bandwidth_down) == 0) {
batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
"Gateway %pM removed from gateway list\n",
orig_node->orig);
/* Note: We don't need a NULL check here, since curr_gw never
* gets dereferenced.
*/
spin_lock_bh(&bat_priv->gw.list_lock);
if (!hlist_unhashed(&gw_node->list)) {
hlist_del_init_rcu(&gw_node->list);
batadv_gw_node_put(gw_node);
}
spin_unlock_bh(&bat_priv->gw.list_lock);
curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
if (gw_node == curr_gw)
batadv_gw_reselect(bat_priv);
if (curr_gw)
batadv_gw_node_put(curr_gw);
}
out:
if (gw_node)
batadv_gw_node_put(gw_node);
}
/**
* batadv_gw_node_delete() - Remove orig_node from gateway list
* @bat_priv: the bat priv with all the soft interface information
* @orig_node: orig node which is currently in process of being removed
*/
void batadv_gw_node_delete(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node)
{
struct batadv_tvlv_gateway_data gateway;
gateway.bandwidth_down = 0;
gateway.bandwidth_up = 0;
batadv_gw_node_update(bat_priv, orig_node, &gateway);
}
/**
* batadv_gw_node_free() - Free gateway information from soft interface
* @bat_priv: the bat priv with all the soft interface information
*/
void batadv_gw_node_free(struct batadv_priv *bat_priv)
{
struct batadv_gw_node *gw_node;
struct hlist_node *node_tmp;
spin_lock_bh(&bat_priv->gw.list_lock);
hlist_for_each_entry_safe(gw_node, node_tmp,
&bat_priv->gw.gateway_list, list) {
hlist_del_init_rcu(&gw_node->list);
batadv_gw_node_put(gw_node);
}
spin_unlock_bh(&bat_priv->gw.list_lock);
}
#ifdef CONFIG_BATMAN_ADV_DEBUGFS
/**
* batadv_gw_client_seq_print_text() - Print the gateway table in a seq file
* @seq: seq file to print on
* @offset: not used
*
* Return: always 0
*/
int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
{
struct net_device *net_dev = (struct net_device *)seq->private;
struct batadv_priv *bat_priv = netdev_priv(net_dev);
struct batadv_hard_iface *primary_if;
primary_if = batadv_seq_print_text_primary_if_get(seq);
if (!primary_if)
return 0;
seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n",
BATADV_SOURCE_VERSION, primary_if->net_dev->name,
primary_if->net_dev->dev_addr, net_dev->name,
bat_priv->algo_ops->name);
batadv_hardif_put(primary_if);
if (!bat_priv->algo_ops->gw.print) {
seq_puts(seq,
"No printing function for this routing protocol\n");
return 0;
}
bat_priv->algo_ops->gw.print(bat_priv, seq);
return 0;
}
#endif
/**
* batadv_gw_dump() - Dump gateways into a message
* @msg: Netlink message to dump into
* @cb: Control block containing additional options
*
* Return: Error code, or length of message
*/
int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb)
{
struct batadv_hard_iface *primary_if = NULL;
struct net *net = sock_net(cb->skb->sk);
struct net_device *soft_iface;
struct batadv_priv *bat_priv;
int ifindex;
int ret;
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);
primary_if = batadv_primary_if_get_selected(bat_priv);
if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
ret = -ENOENT;
goto out;
}
if (!bat_priv->algo_ops->gw.dump) {
ret = -EOPNOTSUPP;
goto out;
}
bat_priv->algo_ops->gw.dump(msg, cb, bat_priv);
ret = msg->len;
out:
if (primary_if)
batadv_hardif_put(primary_if);
if (soft_iface)
dev_put(soft_iface);
return ret;
}
/**
* batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message
* @skb: the packet to check
* @header_len: a pointer to the batman-adv header size
* @chaddr: buffer where the client address will be stored. Valid
* only if the function returns BATADV_DHCP_TO_CLIENT
*
* This function may re-allocate the data buffer of the skb passed as argument.
*
* Return:
* - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
* while parsing it
* - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
* - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
*/
enum batadv_dhcp_recipient
batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
u8 *chaddr)
{
enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
struct ethhdr *ethhdr;
struct iphdr *iphdr;
struct ipv6hdr *ipv6hdr;
struct udphdr *udphdr;
struct vlan_ethhdr *vhdr;
int chaddr_offset;
__be16 proto;
u8 *p;
/* check for ethernet header */
if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
return BATADV_DHCP_NO;
ethhdr = eth_hdr(skb);
proto = ethhdr->h_proto;
*header_len += ETH_HLEN;
/* check for initial vlan header */
if (proto == htons(ETH_P_8021Q)) {
if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
return BATADV_DHCP_NO;
vhdr = vlan_eth_hdr(skb);
proto = vhdr->h_vlan_encapsulated_proto;
*header_len += VLAN_HLEN;
}
/* check for ip header */
switch (proto) {
case htons(ETH_P_IP):
if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
return BATADV_DHCP_NO;
iphdr = (struct iphdr *)(skb->data + *header_len);
*header_len += iphdr->ihl * 4;
/* check for udp header */
if (iphdr->protocol != IPPROTO_UDP)
return BATADV_DHCP_NO;
break;
case htons(ETH_P_IPV6):
if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
return BATADV_DHCP_NO;
ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
*header_len += sizeof(*ipv6hdr);
/* check for udp header */
if (ipv6hdr->nexthdr != IPPROTO_UDP)
return BATADV_DHCP_NO;
break;
default:
return BATADV_DHCP_NO;
}
if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
return BATADV_DHCP_NO;
udphdr = (struct udphdr *)(skb->data + *header_len);
*header_len += sizeof(*udphdr);
/* check for bootp port */
switch (proto) {
case htons(ETH_P_IP):
if (udphdr->dest == htons(67))
ret = BATADV_DHCP_TO_SERVER;
else if (udphdr->source == htons(67))
ret = BATADV_DHCP_TO_CLIENT;
break;
case htons(ETH_P_IPV6):
if (udphdr->dest == htons(547))
ret = BATADV_DHCP_TO_SERVER;
else if (udphdr->source == htons(547))
ret = BATADV_DHCP_TO_CLIENT;
break;
}
chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
/* store the client address if the message is going to a client */
if (ret == BATADV_DHCP_TO_CLIENT &&
pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
/* check if the DHCP packet carries an Ethernet DHCP */
p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
if (*p != BATADV_DHCP_HTYPE_ETHERNET)
return BATADV_DHCP_NO;
/* check if the DHCP packet carries a valid Ethernet address */
p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
if (*p != ETH_ALEN)
return BATADV_DHCP_NO;
ether_addr_copy(chaddr, skb->data + chaddr_offset);
}
return ret;
}
/**
* batadv_gw_out_of_range() - check if the dhcp request destination is the best
* gateway
* @bat_priv: the bat priv with all the soft interface information
* @skb: the outgoing packet
*
* Check if the skb is a DHCP request and if it is sent to the current best GW
* server. Due to topology changes it may be the case that the GW server
* previously selected is not the best one anymore.
*
* This call might reallocate skb data.
* Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
*
* Return: true if the packet destination is unicast and it is not the best gw,
* false otherwise.
*/
bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
struct sk_buff *skb)
{
struct batadv_neigh_node *neigh_curr = NULL;
struct batadv_neigh_node *neigh_old = NULL;
struct batadv_orig_node *orig_dst_node = NULL;
struct batadv_gw_node *gw_node = NULL;
struct batadv_gw_node *curr_gw = NULL;
struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
bool out_of_range = false;
u8 curr_tq_avg;
unsigned short vid;
vid = batadv_get_vid(skb, 0);
if (is_multicast_ether_addr(ethhdr->h_dest))
goto out;
orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
ethhdr->h_dest, vid);
if (!orig_dst_node)
goto out;
gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
if (!gw_node)
goto out;
switch (atomic_read(&bat_priv->gw.mode)) {
case BATADV_GW_MODE_SERVER:
/* If we are a GW then we are our best GW. We can artificially
* set the tq towards ourself as the maximum value
*/
curr_tq_avg = BATADV_TQ_MAX_VALUE;
break;
case BATADV_GW_MODE_CLIENT:
curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
if (!curr_gw)
goto out;
/* packet is going to our gateway */
if (curr_gw->orig_node == orig_dst_node)
goto out;
/* If the dhcp packet has been sent to a different gw,
* we have to evaluate whether the old gw is still
* reliable enough
*/
neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
NULL);
if (!neigh_curr)
goto out;
curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
BATADV_IF_DEFAULT);
if (!curr_ifinfo)
goto out;
curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
batadv_neigh_ifinfo_put(curr_ifinfo);
break;
case BATADV_GW_MODE_OFF:
default:
goto out;
}
neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
if (!neigh_old)
goto out;
old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
if (!old_ifinfo)
goto out;
if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
out_of_range = true;
batadv_neigh_ifinfo_put(old_ifinfo);
out:
if (orig_dst_node)
batadv_orig_node_put(orig_dst_node);
if (curr_gw)
batadv_gw_node_put(curr_gw);
if (gw_node)
batadv_gw_node_put(gw_node);
if (neigh_old)
batadv_neigh_node_put(neigh_old);
if (neigh_curr)
batadv_neigh_node_put(neigh_curr);
return out_of_range;
}