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batman-adv: mcast: fix duplicate mcast packets from BLA backbone to mesh 

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: 279e89b228 ("batman-adv: add broadcast duplicate check")
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>
This commit is contained in:
Linus Lüssing 2020-09-15 09:54:10 +02:00 committed by Simon Wunderlich
parent 74c09b7275
commit 2369e82704
1 changed files with 87 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
net/batman-adv/bridge_loop_avoidance.c
View File

@ -1581,13 +1581,16 @@ 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
@ -1596,19 +1599,17 @@ 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);
@ -1627,8 +1628,21 @@ 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))
continue;
/* 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.
@ -1644,7 +1658,14 @@ 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:
@ -1653,6 +1674,48 @@ out:
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.
@ -1867,6 +1930,14 @@ 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);