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: Antonio Quartulli <ordex@autistici.org>
This commit is contained in:
parent
2f1dfbe185
commit
5c3a0e5535
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@ -4,7 +4,7 @@
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config BATMAN_ADV
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config BATMAN_ADV
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tristate "B.A.T.M.A.N. Advanced Meshing Protocol"
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tristate "B.A.T.M.A.N. Advanced Meshing Protocol"
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depends on NET
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depends on NET && INET
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select CRC16
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select CRC16
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default n
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default n
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help
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help
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@ -16,7 +16,7 @@ config BATMAN_ADV
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config BATMAN_ADV_BLA
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config BATMAN_ADV_BLA
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bool "Bridge Loop Avoidance"
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bool "Bridge Loop Avoidance"
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depends on BATMAN_ADV && INET
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depends on BATMAN_ADV
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default y
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default y
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help
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help
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This option enables BLA (Bridge Loop Avoidance), a mechanism
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This option enables BLA (Bridge Loop Avoidance), a mechanism
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@ -21,6 +21,7 @@
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#include <linux/if_arp.h>
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#include <linux/if_arp.h>
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#include "main.h"
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#include "main.h"
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#include "hash.h"
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#include "distributed-arp-table.h"
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#include "distributed-arp-table.h"
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#include "hard-interface.h"
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#include "hard-interface.h"
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#include "originator.h"
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#include "originator.h"
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@ -141,6 +142,59 @@ static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
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return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
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return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
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}
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}
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/**
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* batadv_arp_hw_src - extract the hw_src field from an ARP packet
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* @skb: ARP packet
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* @hdr_size: size of the possible header before the ARP packet
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*
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* Returns the value of the hw_src field in the ARP packet
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*/
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static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
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{
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uint8_t *addr;
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addr = (uint8_t *)(skb->data + hdr_size);
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addr += ETH_HLEN + sizeof(struct arphdr);
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return addr;
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}
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/**
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* batadv_arp_ip_src - extract the ip_src field from an ARP packet
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* @skb: ARP packet
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* @hdr_size: size of the possible header before the ARP packet
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*
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* Returns the value of the ip_src field in the ARP packet
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*/
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static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
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{
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return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
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}
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/**
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* batadv_arp_hw_dst - extract the hw_dst field from an ARP packet
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* @skb: ARP packet
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* @hdr_size: size of the possible header before the ARP packet
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*
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* Returns the value of the hw_dst field in the ARP packet
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*/
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static uint8_t *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
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{
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return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
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}
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/**
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* batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
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* @skb: ARP packet
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* @hdr_size: size of the possible header before the ARP packet
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*
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* Returns the value of the ip_dst field in the ARP packet
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*/
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static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
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{
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return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
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}
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/**
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/**
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* batadv_hash_dat - compute the hash value for an IP address
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* batadv_hash_dat - compute the hash value for an IP address
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* @data: data to hash
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* @data: data to hash
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@ -257,6 +311,93 @@ out:
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batadv_dat_entry_free_ref(dat_entry);
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batadv_dat_entry_free_ref(dat_entry);
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}
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}
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#ifdef CONFIG_BATMAN_ADV_DEBUG
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/**
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* batadv_dbg_arp - print a debug message containing all the ARP packet details
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* @bat_priv: the bat priv with all the soft interface information
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* @skb: ARP packet
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* @type: ARP type
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* @hdr_size: size of the possible header before the ARP packet
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* @msg: message to print together with the debugging information
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*/
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static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
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uint16_t type, int hdr_size, char *msg)
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{
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struct batadv_unicast_4addr_packet *unicast_4addr_packet;
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struct batadv_bcast_packet *bcast_pkt;
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uint8_t *orig_addr;
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__be32 ip_src, ip_dst;
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if (msg)
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batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
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ip_src = batadv_arp_ip_src(skb, hdr_size);
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ip_dst = batadv_arp_ip_dst(skb, hdr_size);
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
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batadv_arp_hw_src(skb, hdr_size), &ip_src,
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batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
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if (hdr_size == 0)
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return;
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/* if the ARP packet is encapsulated in a batman packet, let's print
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* some debug messages
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*/
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unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
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switch (unicast_4addr_packet->u.header.packet_type) {
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case BATADV_UNICAST:
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"* encapsulated within a UNICAST packet\n");
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break;
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case BATADV_UNICAST_4ADDR:
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
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unicast_4addr_packet->src);
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switch (unicast_4addr_packet->subtype) {
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case BATADV_P_DAT_DHT_PUT:
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batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
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break;
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case BATADV_P_DAT_DHT_GET:
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batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
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break;
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case BATADV_P_DAT_CACHE_REPLY:
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"* type: DAT_CACHE_REPLY\n");
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break;
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case BATADV_P_DATA:
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batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
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break;
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default:
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batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
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unicast_4addr_packet->u.header.packet_type);
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}
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break;
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case BATADV_BCAST:
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bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
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orig_addr = bcast_pkt->orig;
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"* encapsulated within a BCAST packet (src: %pM)\n",
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orig_addr);
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break;
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default:
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batadv_dbg(BATADV_DBG_DAT, bat_priv,
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"* encapsulated within an unknown packet type (0x%x)\n",
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unicast_4addr_packet->u.header.packet_type);
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}
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}
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#else
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static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
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uint16_t type, int hdr_size, char *msg)
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{
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}
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#endif /* CONFIG_BATMAN_ADV_DEBUG */
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/**
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/**
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* batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
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* batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
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* @res: the array with the already selected candidates
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* @res: the array with the already selected candidates
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@ -564,3 +705,64 @@ out:
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batadv_hardif_free_ref(primary_if);
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batadv_hardif_free_ref(primary_if);
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return 0;
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return 0;
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}
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}
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/**
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* batadv_arp_get_type - parse an ARP packet and gets the type
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* @bat_priv: the bat priv with all the soft interface information
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* @skb: packet to analyse
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* @hdr_size: size of the possible header before the ARP packet in the skb
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*
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* Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise
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*/
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static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
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struct sk_buff *skb, int hdr_size)
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{
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struct arphdr *arphdr;
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struct ethhdr *ethhdr;
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__be32 ip_src, ip_dst;
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uint16_t type = 0;
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/* pull the ethernet header */
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if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
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goto out;
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ethhdr = (struct ethhdr *)(skb->data + hdr_size);
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if (ethhdr->h_proto != htons(ETH_P_ARP))
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goto out;
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/* pull the ARP payload */
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if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
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arp_hdr_len(skb->dev))))
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goto out;
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arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
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/* Check whether the ARP packet carries a valid
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* IP information
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*/
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if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
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goto out;
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if (arphdr->ar_pro != htons(ETH_P_IP))
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goto out;
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if (arphdr->ar_hln != ETH_ALEN)
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goto out;
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if (arphdr->ar_pln != 4)
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goto out;
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/* Check for bad reply/request. If the ARP message is not sane, DAT
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* will simply ignore it
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*/
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ip_src = batadv_arp_ip_src(skb, hdr_size);
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ip_dst = batadv_arp_ip_dst(skb, hdr_size);
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if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
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ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst))
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goto out;
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type = ntohs(arphdr->ar_op);
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out:
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return type;
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}
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@ -23,6 +23,8 @@
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#include "types.h"
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#include "types.h"
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#include "originator.h"
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#include "originator.h"
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#include <linux/if_arp.h>
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#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
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#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
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/**
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/**
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@ -37,9 +37,15 @@ enum batadv_packettype {
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/**
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/**
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* enum batadv_subtype - packet subtype for unicast4addr
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* enum batadv_subtype - packet subtype for unicast4addr
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* @BATADV_P_DATA: user payload
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* @BATADV_P_DATA: user payload
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* @BATADV_P_DAT_DHT_GET: DHT request message
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* @BATADV_P_DAT_DHT_PUT: DHT store message
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* @BATADV_P_DAT_CACHE_REPLY: ARP reply generated by DAT
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*/
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*/
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enum batadv_subtype {
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enum batadv_subtype {
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BATADV_P_DATA = 0x01,
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BATADV_P_DATA = 0x01,
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BATADV_P_DAT_DHT_GET = 0x02,
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BATADV_P_DAT_DHT_PUT = 0x03,
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BATADV_P_DAT_CACHE_REPLY = 0x04,
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};
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};
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/* this file is included by batctl which needs these defines */
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/* this file is included by batctl which needs these defines */
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