The following commit has been merged in the master branch: commit 938f2e0b57ffe8a6df71e1e177b2978b1b33fe5e Author: Linus L��ssing linus.luessing@c0d3.blue Date: Sat Jan 1 06:27:13 2022 +0100

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

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: 11d458c1cb9b ("batman-adv: mcast: apply optimizations for routable packets, too") Signed-off-by: Linus L��ssing linus.luessing@c0d3.blue Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c index 433901dcf0c3..f4004cf0ff6f 100644 --- a/net/batman-adv/multicast.c +++ b/net/batman-adv/multicast.c @@ -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; } diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h index 9fee5da08311..8aec818d0bf6 100644 --- a/net/batman-adv/multicast.h +++ b/net/batman-adv/multicast.h @@ -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; diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 7ee09337fc40..2dbbe6c19609 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -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))