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batman-adv: mcast: don't send link-local multicast to mcast routers

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The addition of routable multicast TX handling introduced a
bug/regression for packets with a link-local multicast destination:
These packets would be sent to all batman-adv nodes with a multicast
router and to all batman-adv nodes with an old version without multicast
router detection.

This even disregards the batman-adv multicast fanout setting, which can
potentially lead to an unwanted, high number of unicast transmissions or
even congestion.

Fixing this by avoiding to send link-local multicast packets to nodes in
the multicast router list.

Fixes: 11d458c1cb ("batman-adv: mcast: apply optimizations for routable packets, too")
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 2022-01-01 06:27:13 +01:00 committed by Simon Wunderlich
parent 66f4beaa6c
commit 938f2e0b57
3 changed files with 21 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/batman-adv/multicast.c
View File

@ -1339,6 +1339,7 @@ batadv_mcast_forw_rtr_node_get(struct batadv_priv *bat_priv,
* @bat_priv: the bat priv with all the soft interface information
* @skb: The multicast packet to check
* @orig: an originator to be set to forward the skb to
* @is_routable: stores whether the destination is routable
*
* Return: the forwarding mode as enum batadv_forw_mode and in case of
* BATADV_FORW_SINGLE set the orig to the single originator the skb
@ -1346,17 +1347,16 @@ batadv_mcast_forw_rtr_node_get(struct batadv_priv *bat_priv,
*/
enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **orig)
struct batadv_orig_node **orig, int *is_routable)
{
int ret, tt_count, ip_count, unsnoop_count, total_count;
bool is_unsnoopable = false;
unsigned int mcast_fanout;
struct ethhdr *ethhdr;
int is_routable = 0;
int rtr_count = 0;
ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable,
&is_routable);
is_routable);
if (ret == -ENOMEM)
return BATADV_FORW_NONE;
else if (ret < 0)
@ -1369,7 +1369,7 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
ip_count = batadv_mcast_forw_want_all_ip_count(bat_priv, ethhdr);
unsnoop_count = !is_unsnoopable ? 0 :
atomic_read(&bat_priv->mcast.num_want_all_unsnoopables);
rtr_count = batadv_mcast_forw_rtr_count(bat_priv, is_routable);
rtr_count = batadv_mcast_forw_rtr_count(bat_priv, *is_routable);
total_count = tt_count + ip_count + unsnoop_count + rtr_count;
@ -1689,6 +1689,7 @@ batadv_mcast_forw_want_rtr(struct batadv_priv *bat_priv,
* @bat_priv: the bat priv with all the soft interface information
* @skb: the multicast packet to transmit
* @vid: the vlan identifier
* @is_routable: stores whether the destination is routable
*
* Sends copies of a frame with multicast destination to any node that signaled
* interest in it, that is either via the translation table or the according
@ -1701,7 +1702,7 @@ batadv_mcast_forw_want_rtr(struct batadv_priv *bat_priv,
* is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
*/
int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid)
unsigned short vid, int is_routable)
{
int ret;
@ -1717,12 +1718,16 @@ int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
return ret;
}
if (!is_routable)
goto skip_mc_router;
ret = batadv_mcast_forw_want_rtr(bat_priv, skb, vid);
if (ret != NET_XMIT_SUCCESS) {
kfree_skb(skb);
return ret;
}
skip_mc_router:
consume_skb(skb);
return ret;
}

10
net/batman-adv/multicast.h
View File

@ -43,7 +43,8 @@ enum batadv_forw_mode {
enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **mcast_single_orig);
struct batadv_orig_node **mcast_single_orig,
int *is_routable);
int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct sk_buff *skb,
@ -51,7 +52,7 @@ int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node);
int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid);
unsigned short vid, int is_routable);
void batadv_mcast_init(struct batadv_priv *bat_priv);
@ -68,7 +69,8 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);
static inline enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **mcast_single_orig)
struct batadv_orig_node **mcast_single_orig,
int *is_routable)
{
return BATADV_FORW_ALL;
}
@ -85,7 +87,7 @@ batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
static inline int
batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid)
unsigned short vid, int is_routable)
{
kfree_skb(skb);
return NET_XMIT_DROP;

7
net/batman-adv/soft-interface.c
View File

@ -198,6 +198,7 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
int gw_mode;
enum batadv_forw_mode forw_mode = BATADV_FORW_SINGLE;
struct batadv_orig_node *mcast_single_orig = NULL;
int mcast_is_routable = 0;
int network_offset = ETH_HLEN;
__be16 proto;
@ -300,7 +301,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
send:
if (do_bcast && !is_broadcast_ether_addr(ethhdr->h_dest)) {
forw_mode = batadv_mcast_forw_mode(bat_priv, skb,
&mcast_single_orig);
&mcast_single_orig,
&mcast_is_routable);
if (forw_mode == BATADV_FORW_NONE)
goto dropped;
@ -359,7 +361,8 @@ send:
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);
ret = batadv_mcast_forw_send(bat_priv, skb, vid,
mcast_is_routable);
} else {
if (batadv_dat_snoop_outgoing_arp_request(bat_priv,
skb))