batman-adv: check incoming packet type for bla
If the gateway functionality is used, some broadcast packets (DHCP
requests) may be transmitted as unicast packets. As the bridge loop
avoidance code now only considers the payload Ethernet destination,
it may drop the DHCP request for clients which are claimed by other
backbone gateways, because it falsely infers from the broadcast address
that the right backbone gateway should havehandled the broadcast.
Fix this by checking and delegating the batman-adv packet type used
for transmission.
Reported-by: Guido Iribarren <guidoiribarren@buenosaireslibre.org>
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 8bf9751..c5863f4 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1351,6 +1351,7 @@
* @bat_priv: the bat priv with all the soft interface information
* @skb: the frame to be checked
* @vid: the VLAN ID of the frame
+ * @is_bcast: the packet came in a broadcast packet type.
*
* bla_rx avoidance checks if:
* * we have to race for a claim
@@ -1361,7 +1362,8 @@
* process the skb.
*
*/
-int bla_rx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid)
+int bla_rx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid,
+ bool is_bcast)
{
struct ethhdr *ethhdr;
struct claim search_claim, *claim = NULL;
@@ -1380,7 +1382,7 @@
if (unlikely(atomic_read(&bat_priv->bla_num_requests)))
/* don't allow broadcasts while requests are in flight */
- if (is_multicast_ether_addr(ethhdr->h_dest))
+ if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast)
goto handled;
memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
@@ -1406,8 +1408,13 @@
}
/* if it is a broadcast ... */
- if (is_multicast_ether_addr(ethhdr->h_dest)) {
- /* ... drop it. the responsible gateway is in charge. */
+ if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast) {
+ /* ... drop it. the responsible gateway is in charge.
+ *
+ * We need to check is_bcast because with the gateway
+ * feature, broadcasts (like DHCP requests) may be sent
+ * using a unicast packet type.
+ */
goto handled;
} else {
/* seems the client considers us as its best gateway.