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Message-Id: <1351968514-12357-6-git-send-email-ordex@autistici.org>
Date: Sat, 3 Nov 2012 19:48:30 +0100
From: Antonio Quartulli <ordex@...istici.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
Antonio Quartulli <ordex@...istici.org>
Subject: [PATCH 5/9] 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@...istici.org>
---
net/batman-adv/Kconfig | 4 +-
net/batman-adv/distributed-arp-table.c | 202 +++++++++++++++++++++++++++++++++
net/batman-adv/distributed-arp-table.h | 2 +
net/batman-adv/packet.h | 8 +-
4 files changed, 213 insertions(+), 3 deletions(-)
diff --git a/net/batman-adv/Kconfig b/net/batman-adv/Kconfig
index 53f5244..e77f805 100644
--- a/net/batman-adv/Kconfig
+++ b/net/batman-adv/Kconfig
@@ -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
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index 2ef90e3..49a213c 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/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"
@@ -142,6 +143,59 @@ 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 - compute the hash value for an IP address
* @data: data to hash
* @size: size of the hash table
@@ -257,6 +311,93 @@ 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 (%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 @@ out:
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;
+}
diff --git a/net/batman-adv/distributed-arp-table.h b/net/batman-adv/distributed-arp-table.h
index 1b88303..f4e282a 100644
--- a/net/batman-adv/distributed-arp-table.h
+++ b/net/batman-adv/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)
/**
diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h
index 72d7331..aa3e63a 100644
--- a/net/batman-adv/packet.h
+++ b/net/batman-adv/packet.h
@@ -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_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 */
--
1.7.12.4
--
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