[B.A.T.M.A.N.] [PATCH v6 0/5] Optimizations for setups running dat and bla

[B.A.T.M.A.N.] [PATCH v6 0/5] Optimizations for setups running dat and bla

[Andreas Pape]

This patchset introduces optimizations for batman-adv in setups having several
gateways into a common (switched) Ethernet backbone network especially if dat
is additionally enabled.

Using the current implementation with bla and dat enabled, several problems
can be observed in a real setup:
1. Multiplication of ARP replies from dat enabled gateways and dat enabled
mesh nodes leading to an "ARP reply storm" in the common backbone network.
2. In rare corner cases bla does not fully prevent looping of unicast frames
in the direction Backbone --> mesh --> backbone and looping of multicast
frames in the direction mesh --> backbone --> mesh.
The latter can lead to temporary confusion in the switched backbone resulting
in packet loss and communication timeouts.

The observed problems are solved by introduction of additional rules for the
dat handling, bla packet forwarding and bla claiming/unclaiming of clients.

v6:
 - rebased the patchset
 - removed snooping of all ip traffic

v5:
 - changed function name to batadv_bla_check_claim
 - put added include file in alphabetical order
 - added check to exclude ip address 0.0.0.0 from snooping

v4:
 - removed unnecessary include in soft-interface.c
 - solved issue with double-use and refcounting of pointers in routing.c

v3:

 - rebased patchset
 - moved snooping of ip addresses for dat speed up into separate function
 - removed "patch of a patch"
 - removed automatic claiming during check of a claim
 - fixed issues of the patchset not being compiled due to chosen batman
	options

Kind regards,
Andreas

Andreas Pape (5):
  batman-adv: prevent multiple ARP replies sent by gateways if dat
    enabled
  batman-adv: prevent duplication of ARP replies when DAT is used
  batman-adv: drop unicast packets from other backbone gw
  batman-adv: changed debug messages for easier bla debugging
  batman-adv: handle race condition for claims between gateways

 net/batman-adv/bridge_loop_avoidance.c |   87 +++++++++++++++++++++++++++++---
 net/batman-adv/bridge_loop_avoidance.h |   11 ++++
 net/batman-adv/distributed-arp-table.c |   47 +++++++++++++++++
 net/batman-adv/routing.c               |   25 ++++++++-
 4 files changed, 159 insertions(+), 11 deletions(-)



..................................................................
PHOENIX CONTACT ELECTRONICS GmbH

Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont
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[B.A.T.M.A.N.] [PATCH v6 1/5] batman-adv: prevent multiple ARP replies sent by gateways if dat enabled

[Andreas Pape]

If dat is enabled it must be made sure that only the backbone gw which has
claimed the remote destination for the ARP request answers the ARP request
directly if the MAC address is known due to the local dat table. This
prevents multiple ARP replies in a common backbone if more than one
gateway already knows the remote mac searched for in the ARP request.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/bridge_loop_avoidance.c |   49 ++++++++++++++++++++++++++++++++
 net/batman-adv/bridge_loop_avoidance.h |   11 +++++++
 net/batman-adv/distributed-arp-table.c |   15 ++++++++++
 3 files changed, 75 insertions(+), 0 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index e4f7494..825f40d 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -2046,3 +2046,52 @@ out:
 		batadv_hardif_put(primary_if);
 	return 0;
 }
+
+#ifdef CONFIG_BATMAN_ADV_DAT
+/**
+ * batadv_bla_check_claim - check if address is claimed
+ *
+ * @bat_priv: the bat priv with all the soft interface information
+ * @addr: mac address of which the claim status is checked
+ * @vid: the VLAN ID
+ *
+ * addr is checked if this address is claimed by the local device itself.
+ *
+ * Return: true if bla is disabled or the mac is claimed by the device,
+ * false if the device addr is already claimed by another gateway
+ */
+bool batadv_bla_check_claim(struct batadv_priv *bat_priv,
+			    u8 *addr, unsigned short vid)
+{
+	struct batadv_bla_claim search_claim;
+	struct batadv_bla_claim *claim = NULL;
+	struct batadv_hard_iface *primary_if = NULL;
+	bool ret = true;
+
+	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
+		return ret;
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		return ret;
+
+	/* First look if the mac address is claimed */
+	ether_addr_copy(search_claim.addr, addr);
+	search_claim.vid = vid;
+
+	claim = batadv_claim_hash_find(bat_priv, &search_claim);
+
+	/* If there is a claim and we are not owner of the claim,
+	 * return false.
+	 */
+	if (claim) {
+		if (!batadv_compare_eth(claim->backbone_gw->orig,
+					primary_if->net_dev->dev_addr))
+			ret = false;
+		batadv_claim_put(claim);
+	}
+
+	batadv_hardif_put(primary_if);
+	return ret;
+}
+#endif
diff --git a/net/batman-adv/bridge_loop_avoidance.h b/net/batman-adv/bridge_loop_avoidance.h
index 0f01dae..9dddebc 100644
--- a/net/batman-adv/bridge_loop_avoidance.h
+++ b/net/batman-adv/bridge_loop_avoidance.h
@@ -47,6 +47,10 @@ void batadv_bla_update_orig_address(struct batadv_priv *bat_priv,
 void batadv_bla_status_update(struct net_device *net_dev);
 int batadv_bla_init(struct batadv_priv *bat_priv);
 void batadv_bla_free(struct batadv_priv *bat_priv);
+#ifdef CONFIG_BATMAN_ADV_DAT
+bool batadv_bla_check_claim(struct batadv_priv *bat_priv, u8 *addr,
+			    unsigned short vid);
+#endif

 #define BATADV_BLA_CRC_INIT	0
 #else /* ifdef CONFIG_BATMAN_ADV_BLA */
@@ -112,6 +116,13 @@ static inline void batadv_bla_free(struct batadv_priv *bat_priv)
 {
 }

+static inline
+bool batadv_bla_check_claim(struct batadv_priv *bat_priv, u8 *addr,
+			    unsigned short vid)
+{
+	return true;
+}
+
 #endif /* ifdef CONFIG_BATMAN_ADV_BLA */

 #endif /* ifndef _NET_BATMAN_ADV_BLA_H_ */
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index fa76465..c0346c8 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -43,6 +43,7 @@
 #include <linux/workqueue.h>
 #include <net/arp.h>

+#include "bridge_loop_avoidance.h"
 #include "hard-interface.h"
 #include "hash.h"
 #include "log.h"
@@ -1005,6 +1006,20 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 			goto out;
 		}

+		/* If BLA is enabled, only send ARP replies if we have claimed
+		 * the destination for the ARP request or if no one else of
+		 * the backbone gws belonging to our backbone has claimed the
+		 * destination.
+		 */
+		if (!batadv_bla_check_claim(bat_priv,
+					    dat_entry->mac_addr, vid)) {
+			batadv_dbg(BATADV_DBG_DAT, bat_priv,
+				   "Device %pM claimed by another backbone gw. Don't send ARP reply!",
+				   dat_entry->mac_addr);
+			ret = true;
+			goto out;
+		}
+
 		skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
 				     bat_priv->soft_iface, ip_dst, hw_src,
 				     dat_entry->mac_addr, hw_src);
--
1.7.0.4



..................................................................
PHOENIX CONTACT ELECTRONICS GmbH

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[B.A.T.M.A.N.] [PATCH v6 2/5] batman-adv: prevent duplication of ARP replies when DAT is used

[Andreas Pape]

If none of the backbone gateways in a bla setup has already knowledge of
the mac address searched for in an incoming ARP request from the backbone
an address resolution via the DHT of DAT is started. The gateway can send
several ARP requests to different DHT nodes and therefore can get several
replies. This patch assures that not all of the possible ARP replies are
returned to the backbone by checking the local DAT cache of the gateway.
If there is an entry in the local cache the gateway has already learned
the requested address and there is no need to forward the additional reply
to the backbone.
Furthermore it is checked if this gateway has claimed the source of the ARP
reply and only forwards it to the backbone if it has claimed the source or
if there is no claim at all.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/distributed-arp-table.c |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index c0346c8..6c2e774 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -1191,6 +1191,7 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	__be32 ip_src, ip_dst;
 	u8 *hw_src, *hw_dst;
 	bool dropped = false;
+	struct batadv_dat_entry *dat_entry = NULL;
 	unsigned short vid;

 	if (!atomic_read(&bat_priv->distributed_arp_table))
@@ -1210,12 +1211,41 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);

+	/* If ip_dst is already in cache and has the right mac address,
+	 * drop this frame if this ARP reply is destined for us because it's
+	 * most probably an ARP reply generated by another node of the DHT.
+	 * We have most probably received already a reply earlier. Delivering
+	 * this frame would lead to doubled receive of an ARP reply.
+	 */
+	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
+	if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
+		batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
+			   hw_src, &ip_src, hw_dst, &ip_dst,
+			   dat_entry->mac_addr,	&dat_entry->ip);
+		dropped = true;
+		goto out;
+	}
+
 	/* Update our internal cache with both the IP addresses the node got
 	 * within the ARP reply
 	 */
 	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
 	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);

+	/* If BLA is enabled, only forward ARP replies if we have claimed the
+	 * source of the ARP reply or if no one else of the same backbone has
+	 * already claimed that client. This prevents that different gateways
+	 * to the same backbone all forward the ARP reply leading to multiple
+	 * replies in the backbone.
+	 */
+	if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
+			   hw_src);
+		dropped = true;
+		goto out;
+	}
+
 	/* if this REPLY is directed to a client of mine, let's deliver the
 	 * packet to the interface
 	 */
@@ -1228,6 +1258,8 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 out:
 	if (dropped)
 		kfree_skb(skb);
+	if (dat_entry)
+		batadv_dat_entry_put(dat_entry);
 	/* if dropped == false -> deliver to the interface */
 	return dropped;
 }
--
1.7.0.4



..................................................................
PHOENIX CONTACT ELECTRONICS GmbH

Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont
USt-Id-Nr.: DE811742156
Amtsgericht Hannover HRB 100528 / district court Hannover HRB 100528
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[B.A.T.M.A.N.] [PATCH v6 3/5] batman-adv: drop unicast packets from other backbone gw

[Andreas Pape]

Additional dropping of unicast packets received from another backbone gw of
the same backbone network before being forwarded to the same backbone again
is necessary. It was observed in a test setup that in rare cases these
frames lead to looping unicast traffic backbone->mesh->backbone.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/routing.c |   25 ++++++++++++++++++++++---
 1 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 2bc9645..1511abe 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -877,14 +877,16 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
 	struct batadv_unicast_packet *unicast_packet;
 	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
-	u8 *orig_addr;
-	struct batadv_orig_node *orig_node = NULL;
+	u8 *orig_addr, *orig_addr_gw;
+	struct batadv_orig_node *orig_node = NULL, *orig_node_gw = NULL;
 	int check, hdr_size = sizeof(*unicast_packet);
 	enum batadv_subtype subtype;
-	bool is4addr;
+	bool is4addr, is_gw;
+	struct ethhdr *ethhdr;

 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
 	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
+	ethhdr = eth_hdr(skb);

 	is4addr = unicast_packet->packet_type == BATADV_UNICAST_4ADDR;
 	/* the caller function should have already pulled 2 bytes */
@@ -907,6 +909,23 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,

 	/* packet for me */
 	if (batadv_is_my_mac(bat_priv, unicast_packet->dest)) {
+		/* If this is a unicast packet from another backgone gw,
+		 * drop it.
+		 */
+		orig_addr_gw = ethhdr->h_source;
+		orig_node_gw = batadv_orig_hash_find(bat_priv, orig_addr_gw);
+		if (orig_node_gw) {
+			is_gw = batadv_bla_is_backbone_gw(skb, orig_node_gw,
+							  hdr_size);
+			batadv_orig_node_put(orig_node_gw);
+			if (is_gw) {
+				batadv_dbg(BATADV_DBG_BLA, bat_priv,
+					   "Dropped unicast pkt received from another backbone gw %pM.\n",
+					   orig_addr_gw);
+				return NET_RX_DROP;
+			}
+		}
+
 		if (is4addr) {
 			subtype = unicast_4addr_packet->subtype;
 			batadv_dat_inc_counter(bat_priv, subtype);
--
1.7.0.4



..................................................................
PHOENIX CONTACT ELECTRONICS GmbH

Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont
USt-Id-Nr.: DE811742156
Amtsgericht Hannover HRB 100528 / district court Hannover HRB 100528
Geschäftsführer / Executive Board: Ulrich Leidecker, Christoph Leifer
__________________________________________________________________
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[B.A.T.M.A.N.] [PATCH v6 4/5] batman-adv: changed debug messages for easier bla debugging

[Andreas Pape]

Some of the bla debug messages are extended and additional messages are
added for easier bla debugging. Some debug messages introduced with the
dat changes in prior patches of this patch series have been changed to
be more compliant to other existing debug messages.

Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
---
 net/batman-adv/bridge_loop_avoidance.c |   18 ++++++++++++++----
 net/batman-adv/routing.c               |    2 +-
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 825f40d..7ec11ac 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -716,8 +716,8 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv,
 			goto claim_free_ref;

 		batadv_dbg(BATADV_DBG_BLA, bat_priv,
-			   "bla_add_claim(): changing ownership for %pM, vid %d\n",
-			   mac, BATADV_PRINT_VID(vid));
+			   "bla_add_claim(): changing ownership for %pM, vid %d to gw %pM\n",
+			   mac, BATADV_PRINT_VID(vid), backbone_gw->orig);

 		spin_lock_bh(&claim->backbone_gw->crc_lock);
 		claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
@@ -1241,10 +1241,13 @@ static void batadv_bla_purge_claims(struct batadv_priv *bat_priv,
 				continue;

 			batadv_dbg(BATADV_DBG_BLA, bat_priv,
-				   "bla_purge_claims(): %pM, vid %d, time out\n",
+				   "bla_purge_claims(): timed out.\n");
+
+purge_now:
+			batadv_dbg(BATADV_DBG_BLA, bat_priv,
+				   "bla_purge_claims(): %pM, vid %d\n",
 				   claim->addr, claim->vid);

-purge_now:
 			batadv_handle_unclaim(bat_priv, primary_if,
 					      claim->backbone_gw->orig,
 					      claim->addr, claim->vid);
@@ -1788,6 +1791,13 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		/* possible optimization: race for a claim */
 		/* No claim exists yet, claim it for us!
 		 */
+
+		batadv_dbg(BATADV_DBG_BLA, bat_priv,
+			   "bla_rx(): Unclaimed MAC %pM found. Claim it. Local: %s\n",
+			   ethhdr->h_source,
+			   batadv_is_my_client(bat_priv,
+					       ethhdr->h_source, vid) ?
+			   "yes" : "no");
 		batadv_handle_claim(bat_priv, primary_if,
 				    primary_if->net_dev->dev_addr,
 				    ethhdr->h_source, vid);
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 1511abe..79fae64 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -920,7 +920,7 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 			batadv_orig_node_put(orig_node_gw);
 			if (is_gw) {
 				batadv_dbg(BATADV_DBG_BLA, bat_priv,
-					   "Dropped unicast pkt received from another backbone gw %pM.\n",
+					   "recv_unicast_packet(): Dropped unicast pkt received from another backbone gw %pM.\n",
 					   orig_addr_gw);
 				return NET_RX_DROP;
 			}
--
1.7.0.4



..................................................................
PHOENIX CONTACT ELECTRONICS GmbH

Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont
USt-Id-Nr.: DE811742156
Amtsgericht Hannover HRB 100528 / district court Hannover HRB 100528
Geschäftsführer / Executive Board: Ulrich Leidecker, Christoph Leifer
__________________________________________________________________
Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren, jegliche anderweitige Verwendung sowie die unbefugte Weitergabe dieser Mail ist nicht gestattet.
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___________________________________________________________________

[B.A.T.M.A.N.] [PATCH v6 5/5] batman-adv: handle race condition for claims between gateways

[Andreas Pape]

Consider the following situation which has been found in a test setup:
Gateway B has claimed client C and gateway A has the same backbone
network as B. C sends a broad- or multicast to B and directly after
this packet decides to send another packet to A due to a better TQ
value. B will forward the broad-/multicast into the backbone as it is
the responsible gw and after that A will claim C as it has been
chosen by C as the best gateway. If it now happens that A claims C
before it has received the broad-/multicast forwarded by B (due to
backbone topology or due to some delay in B when forwarding the
packet) we get a critical situation: in the current code A will
immediately unclaim C when receiving the multicast due to the
roaming client scenario although the position of C has not changed
in the mesh. If this happens the multi-/broadcast forwarded by B
will be sent back into the mesh by A and we have looping packets
until one of the gateways claims C again.
In order to prevent this, unclaiming of a client due to the roaming
client scenario is only done after a certain time is expired after
the last claim of the client. 100 ms are used here, which should be
slow enough for big backbones and slow gateways but fast enough not
to break the roaming client use case.

Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
---
 net/batman-adv/bridge_loop_avoidance.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 7ec11ac..07fc153 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1905,10 +1905,22 @@ bool batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		/* if yes, the client has roamed and we have
 		 * to unclaim it.
 		 */
-		batadv_handle_unclaim(bat_priv, primary_if,
-				      primary_if->net_dev->dev_addr,
-				      ethhdr->h_source, vid);
-		goto allow;
+		if (batadv_has_timed_out(claim->lasttime, 100)) {
+			/* only unclaim if the last claim entry is
+			 * older than 100 ms to make sure we really
+			 * have a roaming client here.
+			 */
+			batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Roaming client %pM detected. Unclaim it.\n",
+				   ethhdr->h_source);
+			batadv_handle_unclaim(bat_priv, primary_if,
+					      primary_if->net_dev->dev_addr,
+					      ethhdr->h_source, vid);
+			goto allow;
+		} else {
+			batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Race for claim %pM detected. Drop packet.\n",
+				   ethhdr->h_source);
+			goto handled;
+		}
 	}

 	/* check if it is a multicast/broadcast frame */
--
1.7.0.4



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