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3236d215ad
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: 2d3f6ccc4e ("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>
125 lines
2.9 KiB
C
125 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2014-2020 B.A.T.M.A.N. contributors:
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*
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* Linus Lüssing
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*/
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#ifndef _NET_BATMAN_ADV_MULTICAST_H_
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#define _NET_BATMAN_ADV_MULTICAST_H_
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#include "main.h"
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#include <linux/netlink.h>
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#include <linux/seq_file.h>
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#include <linux/skbuff.h>
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/**
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* enum batadv_forw_mode - the way a packet should be forwarded as
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*/
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enum batadv_forw_mode {
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/**
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* @BATADV_FORW_ALL: forward the packet to all nodes (currently via
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* classic flooding)
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*/
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BATADV_FORW_ALL,
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/**
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* @BATADV_FORW_SOME: forward the packet to some nodes (currently via
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* a multicast-to-unicast conversion and the BATMAN unicast routing
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* protocol)
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*/
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BATADV_FORW_SOME,
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/**
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* @BATADV_FORW_SINGLE: forward the packet to a single node (currently
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* via the BATMAN unicast routing protocol)
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*/
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BATADV_FORW_SINGLE,
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/** @BATADV_FORW_NONE: don't forward, drop it */
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BATADV_FORW_NONE,
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};
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#ifdef CONFIG_BATMAN_ADV_MCAST
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enum batadv_forw_mode
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batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
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struct batadv_orig_node **mcast_single_orig);
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int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
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struct sk_buff *skb,
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unsigned short vid,
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struct batadv_orig_node *orig_node);
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int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
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unsigned short vid);
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void batadv_mcast_init(struct batadv_priv *bat_priv);
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int batadv_mcast_flags_seq_print_text(struct seq_file *seq, void *offset);
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int batadv_mcast_mesh_info_put(struct sk_buff *msg,
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struct batadv_priv *bat_priv);
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int batadv_mcast_flags_dump(struct sk_buff *msg, struct netlink_callback *cb);
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void batadv_mcast_free(struct batadv_priv *bat_priv);
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void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);
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#else
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static inline enum batadv_forw_mode
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batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
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struct batadv_orig_node **mcast_single_orig)
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{
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return BATADV_FORW_ALL;
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}
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static inline int
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batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
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struct sk_buff *skb,
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unsigned short vid,
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struct batadv_orig_node *orig_node)
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{
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kfree_skb(skb);
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return NET_XMIT_DROP;
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}
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static inline int
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batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
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unsigned short vid)
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{
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kfree_skb(skb);
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return NET_XMIT_DROP;
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}
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static inline int batadv_mcast_init(struct batadv_priv *bat_priv)
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{
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return 0;
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}
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static inline int
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batadv_mcast_mesh_info_put(struct sk_buff *msg, struct batadv_priv *bat_priv)
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{
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return 0;
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}
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static inline int batadv_mcast_flags_dump(struct sk_buff *msg,
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struct netlink_callback *cb)
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{
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return -EOPNOTSUPP;
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}
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static inline void batadv_mcast_free(struct batadv_priv *bat_priv)
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{
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}
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static inline void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node)
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{
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}
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#endif /* CONFIG_BATMAN_ADV_MCAST */
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#endif /* _NET_BATMAN_ADV_MULTICAST_H_ */
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