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Commit d670b96a authored by Linus Lüssing's avatar Linus Lüssing Committed by Greg Kroah-Hartman
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batman-adv: mcast: fix duplicate mcast packets from BLA backbone to mesh 



commit 2369e827046920ef0599e6a36b975ac5c0a359c2 upstream.

Scenario:
* Multicast frame send from BLA backbone gateways (multiple nodes
  with their bat0 bridged together, with BLA enabled) sharing the same
  LAN to nodes in the mesh

Issue:
* Nodes receive the frame multiple times on bat0 from the mesh,
  once from each foreign BLA backbone gateway which shares the same LAN
  with another

For multicast frames via batman-adv broadcast packets coming from the
same BLA backbone but from different backbone gateways duplicates are
currently detected via a CRC history of previously received packets.

However this CRC so far was not performed for multicast frames received
via batman-adv unicast packets. Fixing this by appyling the same check
for such packets, too.

Room for improvements in the future: Ideally we would introduce the
possibility to not only claim a client, but a complete originator, too.
This would allow us to only send a multicast-in-unicast packet from a BLA
backbone gateway claiming the node and by that avoid potential redundant
transmissions in the first place.

Fixes: e5cf86d30a9b ("batman-adv: add broadcast duplicate check")
Signed-off-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
[ bp: 4.9 backported: adjust context, correct fixes line ]
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a9063487

net/batman-adv/bridge_loop_avoidance.c

+87 −16
Original line number Diff line number Diff line
@@ -1593,13 +1593,16 @@ int batadv_bla_init(struct batadv_priv *bat_priv) 
}



/**

 * batadv_bla_check_bcast_duplist - Check if a frame is in the broadcast dup.

 * batadv_bla_check_duplist() - Check if a frame is in the broadcast dup.

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: contains the bcast_packet to be checked

 * @skb: contains the multicast packet to be checked

 * @payload_ptr: pointer to position inside the head buffer of the skb

 *  marking the start of the data to be CRC'ed

 * @orig: originator mac address, NULL if unknown

 *

 * check if it is on our broadcast list. Another gateway might

 * have sent the same packet because it is connected to the same backbone,

 * so we have to remove this duplicate.

 * Check if it is on our broadcast list. Another gateway might have sent the

 * same packet because it is connected to the same backbone, so we have to

 * remove this duplicate.

 *

 * This is performed by checking the CRC, which will tell us

 * with a good chance that it is the same packet. If it is furthermore
@@ -1608,19 +1611,17 @@ int batadv_bla_init(struct batadv_priv *bat_priv) 
 *

 * Return: true if a packet is in the duplicate list, false otherwise.

 */

bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,

				    struct sk_buff *skb)

static bool batadv_bla_check_duplist(struct batadv_priv *bat_priv,

				     struct sk_buff *skb, u8 *payload_ptr,

				     const u8 *orig)

{

	int i, curr;

	__be32 crc;

	struct batadv_bcast_packet *bcast_packet;

	struct batadv_bcast_duplist_entry *entry;

	bool ret = false;



	bcast_packet = (struct batadv_bcast_packet *)skb->data;

	int i, curr;

	__be32 crc;



	/* calculate the crc ... */

	crc = batadv_skb_crc32(skb, (u8 *)(bcast_packet + 1));

	crc = batadv_skb_crc32(skb, payload_ptr);



	spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);
@@ -1639,8 +1640,21 @@ bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, 
		if (entry->crc != crc)

			continue;



		if (batadv_compare_eth(entry->orig, bcast_packet->orig))

		/* are the originators both known and not anonymous? */

		if (orig && !is_zero_ether_addr(orig) &&

		    !is_zero_ether_addr(entry->orig)) {

			/* If known, check if the new frame came from

			 * the same originator:

			 * We are safe to take identical frames from the

			 * same orig, if known, as multiplications in

			 * the mesh are detected via the (orig, seqno) pair.

			 * So we can be a bit more liberal here and allow

			 * identical frames from the same orig which the source

			 * host might have sent multiple times on purpose.

			 */

			if (batadv_compare_eth(entry->orig, orig))

				continue;

		}



		/* this entry seems to match: same crc, not too old,

		 * and from another gw. therefore return true to forbid it.
@@ -1656,7 +1670,14 @@ bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, 
	entry = &bat_priv->bla.bcast_duplist[curr];

	entry->crc = crc;

	entry->entrytime = jiffies;

	ether_addr_copy(entry->orig, bcast_packet->orig);



	/* known originator */

	if (orig)

		ether_addr_copy(entry->orig, orig);

	/* anonymous originator */

	else

		eth_zero_addr(entry->orig);



	bat_priv->bla.bcast_duplist_curr = curr;



out:
@@ -1665,6 +1686,48 @@ bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, 
	return ret;

}



/**

 * batadv_bla_check_ucast_duplist() - Check if a frame is in the broadcast dup.

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: contains the multicast packet to be checked, decapsulated from a

 *  unicast_packet

 *

 * Check if it is on our broadcast list. Another gateway might have sent the

 * same packet because it is connected to the same backbone, so we have to

 * remove this duplicate.

 *

 * Return: true if a packet is in the duplicate list, false otherwise.

 */

static bool batadv_bla_check_ucast_duplist(struct batadv_priv *bat_priv,

					   struct sk_buff *skb)

{

	return batadv_bla_check_duplist(bat_priv, skb, (u8 *)skb->data, NULL);

}



/**

 * batadv_bla_check_bcast_duplist() - Check if a frame is in the broadcast dup.

 * @bat_priv: the bat priv with all the soft interface information

 * @skb: contains the bcast_packet to be checked

 *

 * Check if it is on our broadcast list. Another gateway might have sent the

 * same packet because it is connected to the same backbone, so we have to

 * remove this duplicate.

 *

 * Return: true if a packet is in the duplicate list, false otherwise.

 */

bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,

				    struct sk_buff *skb)

{

	struct batadv_bcast_packet *bcast_packet;

	u8 *payload_ptr;



	bcast_packet = (struct batadv_bcast_packet *)skb->data;

	payload_ptr = (u8 *)(bcast_packet + 1);



	return batadv_bla_check_duplist(bat_priv, skb, payload_ptr,

					bcast_packet->orig);

}



/**

 * batadv_bla_is_backbone_gw_orig - Check if the originator is a gateway for

 *  the VLAN identified by vid.
@@ -1879,6 +1942,14 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb, 
			    packet_type == BATADV_UNICAST)

				goto handled;



	/* potential duplicates from foreign BLA backbone gateways via

	 * multicast-in-unicast packets

	 */

	if (is_multicast_ether_addr(ethhdr->h_dest) &&

	    packet_type == BATADV_UNICAST &&

	    batadv_bla_check_ucast_duplist(bat_priv, skb))

		goto handled;



	ether_addr_copy(search_claim.addr, ethhdr->h_source);

	search_claim.vid = vid;

	claim = batadv_claim_hash_find(bat_priv, &search_claim);