Staging: batman-adv: Adding netfilter-bridge hooks

batman-adv is receiving and sending the packets of its own ether type
on a very early/low level. Therefore we need to add explicit hooks to
give netfilter/ebtables a chance to filter them.
Reported-by: Antonio Quartulli <ordex@ritirata.org>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/batman-adv/hard-interface.c

@@ -30,6 +30,7 @@
 #include "hash.h"
 
 #include <linux/if_arp.h>
+#include <linux/netfilter_bridge.h>
 
 #define MIN(x, y) ((x) < (y) ? (x) : (y))
 
@@ -432,6 +433,11 @@ static int hard_if_event(struct notifier_block *this,
 	return NOTIFY_DONE;
 }
 
+static int batman_skb_recv_finish(struct sk_buff *skb)
+{
+	return NF_ACCEPT;
+}
+
 /* receive a packet with the batman ethertype coming on a hard
  * interface */
 int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
@@ -451,6 +457,13 @@ int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 	if (atomic_read(&module_state) != MODULE_ACTIVE)
 		goto err_free;
 
+	/* if netfilter/ebtables wants to block incoming batman
+	 * packets then give them a chance to do so here */
+	ret = NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, dev, NULL,
+		      batman_skb_recv_finish);
+	if (ret != 1)
+		goto err_out;
+
 	/* packet should hold at least type and version */
 	if (unlikely(skb_headlen(skb) < 2))
 		goto err_free;
@@ -530,7 +543,6 @@ int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 	return NET_RX_DROP;
 }
 
-
 struct notifier_block hard_if_notifier = {
 	.notifier_call = hard_if_event,
 };

drivers/staging/batman-adv/send.c

@@ -29,6 +29,8 @@
 #include "vis.h"
 #include "aggregation.h"
 
+#include <linux/netfilter_bridge.h>
+
 /* apply hop penalty for a normal link */
 static uint8_t hop_penalty(const uint8_t tq)
 {
@@ -90,9 +92,12 @@ int send_skb_packet(struct sk_buff *skb,
 
 	/* dev_queue_xmit() returns a negative result on error.	 However on
 	 * congestion and traffic shaping, it drops and returns NET_XMIT_DROP
-	 * (which is > 0). This will not be treated as an error. */
+	 * (which is > 0). This will not be treated as an error.
+	 * Also, if netfilter/ebtables wants to block outgoing batman
+	 * packets then giving them a chance to do so here */
 
-	return dev_queue_xmit(skb);
+	return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
+		       dev_queue_xmit);
 send_skb_err:
 	kfree_skb(skb);
 	return NET_XMIT_DROP;