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Commit 5c3a0e55 authored by Antonio Quartulli's avatar Antonio Quartulli
Browse files

batman-adv: Distributed ARP Table - add ARP parsing functions 



ARP messages are now parsed to make it possible to trigger special actions
depending on their types (snooping).

Signed-off-by: default avatarAntonio Quartulli <ordex@autistici.org>
parent 2f1dfbe1

net/batman-adv/Kconfig

+2 −2
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 


config BATMAN_ADV

	tristate "B.A.T.M.A.N. Advanced Meshing Protocol"

	depends on NET

	depends on NET && INET

	select CRC16

        default n

	help
@@ -16,7 +16,7 @@ config BATMAN_ADV 


config BATMAN_ADV_BLA

	bool "Bridge Loop Avoidance"

	depends on BATMAN_ADV && INET

	depends on BATMAN_ADV

	default y

	help

	  This option enables BLA (Bridge Loop Avoidance), a mechanism

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

+202 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/if_arp.h>



#include "main.h"

#include "hash.h"

#include "distributed-arp-table.h"

#include "hard-interface.h"

#include "originator.h"
@@ -141,6 +142,59 @@ static int batadv_compare_dat(const struct hlist_node *node, const void *data2) 
	return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 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

 *

 * Returns the value of the hw_src field in the ARP packet

 */

static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)

{

	uint8_t *addr;



	addr = (uint8_t *)(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

 *

 * Returns 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 *(__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

 *

 * Returns the value of the hw_dst field in the ARP packet

 */

static uint8_t *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

 *

 * Returns the value of the ip_dst field in the ARP packet

 */

static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)

{

	return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);

}



/**

 * batadv_hash_dat - compute the hash value for an IP address

 * @data: data to hash
@@ -257,6 +311,93 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip, 
		batadv_dat_entry_free_ref(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

 * @type: ARP type

 * @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,

			   uint16_t type, int hdr_size, char *msg)

{

	struct batadv_unicast_4addr_packet *unicast_4addr_packet;

	struct batadv_bcast_packet *bcast_pkt;

	uint8_t *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 == 0)

		return;



	/* if the ARP packet is encapsulated in a batman packet, let's print

	 * some debug messages

	 */

	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;



	switch (unicast_4addr_packet->u.header.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.header.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.header.packet_type);

	}

}



#else



static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,

			   uint16_t type, 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
@@ -564,3 +705,64 @@ int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset) 
		batadv_hardif_free_ref(primary_if);

	return 0;

}



/**

 * 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

 *

 * Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise

 */

static uint16_t 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;

	uint16_t 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))

		goto out;



	type = ntohs(arphdr->ar_op);

out:

	return type;

}

net/batman-adv/distributed-arp-table.h

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include "types.h"

#include "originator.h"



#include <linux/if_arp.h>



#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)



/**

net/batman-adv/packet.h

+7 −1
Original line number Diff line number Diff line
@@ -37,9 +37,15 @@ enum batadv_packettype { 
/**

 * enum batadv_subtype - packet subtype for unicast4addr

 * @BATADV_P_DATA: user payload

 * @BATADV_P_DAT_DHT_GET: DHT request message

 * @BATADV_P_DAT_DHT_PUT: DHT store message

 * @BATADV_P_DAT_CACHE_REPLY: ARP reply generated by DAT

 */

enum batadv_subtype {

	BATADV_P_DATA			= 0x01,

	BATADV_P_DAT_DHT_GET		= 0x02,

	BATADV_P_DAT_DHT_PUT		= 0x03,

	BATADV_P_DAT_CACHE_REPLY	= 0x04,

};



/* this file is included by batctl which needs these defines */