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authorLinus Lüssing <linus.luessing@c0d3.blue>2020-09-15 09:54:08 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-10-01 13:18:19 +0200
commit24e5e941d804a2f6641e7d629f6b5a795403a213 (patch)
tree63809c3523c7f36b6b64adf6de3b166ee523b297 /net/batman-adv
parentb0632590cbec1b55a94186d1b3e294811595d027 (diff)
batman-adv: mcast: fix duplicate mcast packets in BLA backbone from LAN
[ Upstream commit 3236d215ad38a3f5372e65cd1e0a52cf93d3c6a2 ] Scenario: * Multicast frame send from a BLA backbone (multiple nodes with their bat0 bridged together, with BLA enabled) Issue: * BLA backbone nodes receive the frame multiple times on bat0 For multicast frames received via batman-adv broadcast packets the originator of the broadcast packet is checked before decapsulating and forwarding the frame to bat0 (batadv_bla_is_backbone_gw()-> batadv_recv_bcast_packet()). If it came from a node which shares the same BLA backbone with us then it is not forwarded to bat0 to avoid a loop. When sending a multicast frame in a non-4-address batman-adv unicast packet we are currently missing this check - and cannot do so because the batman-adv unicast packet has no originator address field. However, we can simply fix this on the sender side by only sending the multicast frame via unicasts to interested nodes which do not share the same BLA backbone with us. This also nicely avoids some unnecessary transmissions on mesh side. Note that no infinite loop was observed, probably because of dropping via batadv_interface_tx()->batadv_bla_tx(). However the duplicates still utterly confuse switches/bridges, ICMPv6 duplicate address detection and neighbor discovery and therefore leads to long delays before being able to establish TCP connections, for instance. And it also leads to the Linux bridge printing messages like: "br-lan: received packet on eth1 with own address as source address ..." Fixes: 2d3f6ccc4ea5 ("batman-adv: Modified forwarding behaviour for multicast packets") Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> Signed-off-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/batman-adv')
-rw-r--r--net/batman-adv/multicast.c46
-rw-r--r--net/batman-adv/multicast.h15
-rw-r--r--net/batman-adv/soft-interface.c5
3 files changed, 53 insertions, 13 deletions
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 1d5bdf3a4b65..f5bf931252c4 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -51,6 +51,7 @@
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>
+#include "bridge_loop_avoidance.h"
#include "hard-interface.h"
#include "hash.h"
#include "log.h"
@@ -1435,6 +1436,35 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
}
/**
+ * batadv_mcast_forw_send_orig() - send a multicast packet to an originator
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to send
+ * @vid: the vlan identifier
+ * @orig_node: the originator to send the packet to
+ *
+ * Return: NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
+ */
+int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+ struct sk_buff *skb,
+ unsigned short vid,
+ struct batadv_orig_node *orig_node)
+{
+ /* Avoid sending multicast-in-unicast packets to other BLA
+ * gateways - they already got the frame from the LAN side
+ * we share with them.
+ * TODO: Refactor to take BLA into account earlier, to avoid
+ * reducing the mcast_fanout count.
+ */
+ if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig, vid)) {
+ dev_kfree_skb(skb);
+ return NET_XMIT_SUCCESS;
+ }
+
+ return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
+ orig_node, vid);
+}
+
+/**
* batadv_mcast_forw_tt() - forwards a packet to multicast listeners
* @bat_priv: the bat priv with all the soft interface information
* @skb: the multicast packet to transmit
@@ -1471,8 +1501,8 @@ batadv_mcast_forw_tt(struct batadv_priv *bat_priv, struct sk_buff *skb,
break;
}
- batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
- orig_entry->orig_node, vid);
+ batadv_mcast_forw_send_orig(bat_priv, newskb, vid,
+ orig_entry->orig_node);
}
rcu_read_unlock();
@@ -1513,8 +1543,7 @@ batadv_mcast_forw_want_all_ipv4(struct batadv_priv *bat_priv,
break;
}
- batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
- orig_node, vid);
+ batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
}
rcu_read_unlock();
return ret;
@@ -1551,8 +1580,7 @@ batadv_mcast_forw_want_all_ipv6(struct batadv_priv *bat_priv,
break;
}
- batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
- orig_node, vid);
+ batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
}
rcu_read_unlock();
return ret;
@@ -1618,8 +1646,7 @@ batadv_mcast_forw_want_all_rtr4(struct batadv_priv *bat_priv,
break;
}
- batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
- orig_node, vid);
+ batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
}
rcu_read_unlock();
return ret;
@@ -1656,8 +1683,7 @@ batadv_mcast_forw_want_all_rtr6(struct batadv_priv *bat_priv,
break;
}
- batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
- orig_node, vid);
+ batadv_mcast_forw_send_orig(bat_priv, newskb, vid, orig_node);
}
rcu_read_unlock();
return ret;
diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h
index 5d9e2bb29c97..403929013ac4 100644
--- a/net/batman-adv/multicast.h
+++ b/net/batman-adv/multicast.h
@@ -46,6 +46,11 @@ enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **mcast_single_orig);
+int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+ struct sk_buff *skb,
+ unsigned short vid,
+ struct batadv_orig_node *orig_node);
+
int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid);
@@ -72,6 +77,16 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
}
static inline int
+batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+ struct sk_buff *skb,
+ unsigned short vid,
+ struct batadv_orig_node *orig_node)
+{
+ kfree_skb(skb);
+ return NET_XMIT_DROP;
+}
+
+static inline int
batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid)
{
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 5ee8e9a100f9..cf1a8ef7464f 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -364,9 +364,8 @@ send:
goto dropped;
ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
} else if (mcast_single_orig) {
- ret = batadv_send_skb_unicast(bat_priv, skb,
- BATADV_UNICAST, 0,
- mcast_single_orig, vid);
+ ret = batadv_mcast_forw_send_orig(bat_priv, skb, vid,
+ mcast_single_orig);
} else if (forw_mode == BATADV_FORW_SOME) {
ret = batadv_mcast_forw_send(bat_priv, skb, vid);
} else {