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 --- distributed-arp-table.c | 201 +++++++++++++++++++++++++++++++++++++++++++++++ distributed-arp-table.h | 2 + packet.h | 5 +- 3 files changed, 207 insertions(+), 1 deletion(-)
diff --git a/distributed-arp-table.c b/distributed-arp-table.c index 2ccd279..9cac8af 100644 --- a/distributed-arp-table.c +++ b/distributed-arp-table.c @@ -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" @@ -112,6 +113,59 @@ static int batadv_compare_dat(const struct hlist_node *node, const void *data2) }
/** + * 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_global - compute the hash value for the global DAT cache * @data: data to hash * @size: size of the hash table @@ -258,6 +312,92 @@ out: 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!\n"); + } + 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 @@ -599,3 +739,64 @@ out: batadv_hardif_free_ref(primary_if); 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 + * + * 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; +} diff --git a/distributed-arp-table.h b/distributed-arp-table.h index 0014583..9096749 100644 --- a/distributed-arp-table.h +++ b/distributed-arp-table.h @@ -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)
static inline void diff --git a/packet.h b/packet.h index 0656df3..6d7a0a0 100644 --- a/packet.h +++ b/packet.h @@ -38,7 +38,10 @@ enum batadv_packettype { * enum batadv_subtype - packet subtype for unicast4addr */ enum batadv_subtype { - BATADV_P_DATA = 0x01, + 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 */