[linux-next] LinuxNextTracking branch, master, updated. next-20150810

batman at open-mesh.org batman at open-mesh.org
Tue Aug 11 00:15:39 CEST 2015

The following commit has been merged in the master branch:
commit f202a666e933f3c7557126d63833a6a3b577ac15
Author: Antonio Quartulli <antonio at meshcoding.com>
Date:   Tue Jun 16 21:06:24 2015 +0200

    batman-adv: avoid DAT to mess up LAN state
    When a node running DAT receives an ARP request from the LAN for the
    first time, it is likely that this node will request the ARP entry
    through the distributed ARP table (DAT) in the mesh.
    Once a DAT reply is received the asking node must check if the MAC
    address for which the IP address has been asked is local. If it is, the
    node must drop the ARP reply bceause the client should have replied on
    its own locally.
    Forwarding this reply means fooling any L2 bridge (e.g. Ethernet
    switches) lying between the batman-adv node and the LAN. This happens
    because the L2 bridge will think that the client sending the ARP reply
    lies somewhere in the mesh, while this node is sitting in the same LAN.
    Reported-by: Simon Wunderlich <sw at simonwunderlich.de>
    Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Antonio Quartulli <antonio at meshcoding.com>

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index fb54e6a..6d0b471 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -1138,6 +1138,9 @@ void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: packet to check
  * @hdr_size: size of the encapsulation header
+ *
+ * Returns true if the packet was snooped and consumed by DAT. False if the
+ * packet has to be delivered to the interface
 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 					 struct sk_buff *skb, int hdr_size)
@@ -1145,7 +1148,7 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	uint16_t type;
 	__be32 ip_src, ip_dst;
 	uint8_t *hw_src, *hw_dst;
-	bool ret = false;
+	bool dropped = false;
 	unsigned short vid;
 	if (!atomic_read(&bat_priv->distributed_arp_table))
@@ -1174,12 +1177,17 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	/* if this REPLY is directed to a client of mine, let's deliver the
 	 * packet to the interface
-	ret = !batadv_is_my_client(bat_priv, hw_dst, vid);
+	dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
+	/* if this REPLY is sent on behalf of a client of mine, let's drop the
+	 * packet because the client will reply by itself
+	 */
+	dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
-	if (ret)
+	if (dropped)
-	/* if ret == false -> packet has to be delivered to the interface */
-	return ret;
+	/* if dropped == false -> deliver to the interface */
+	return dropped;


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