This is a note to let you know that I've just added the patch titled batman-adv: mcast: don't send link-local multicast to mcast routers to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: batman-adv-mcast-don-t-send-link-local-multicast-to-mcast-routers.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 938f2e0b57ffe8a6df71e1e177b2978b1b33fe5e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@xxxxxxxxx> Date: Sat, 1 Jan 2022 06:27:13 +0100 Subject: batman-adv: mcast: don't send link-local multicast to mcast routers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Linus Lüssing <linus.luessing@xxxxxxxxx> commit 938f2e0b57ffe8a6df71e1e177b2978b1b33fe5e upstream. 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 Lüssing <linus.luessing@xxxxxxxxx> Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx> Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/batman-adv/multicast.c | 15 ++++++++++----- net/batman-adv/multicast.h | 10 ++++++---- net/batman-adv/soft-interface.c | 7 +++++-- 3 files changed, 21 insertions(+), 11 deletions(-) --- a/net/batman-adv/multicast.c +++ b/net/batman-adv/multicast.c @@ -1339,6 +1339,7 @@ batadv_mcast_forw_rtr_node_get(struct ba * @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 ba */ 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_pri 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 * @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 * 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 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; } --- 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 b 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 bata 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 batad 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; --- 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(s 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(s 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)) Patches currently in stable-queue which might be from linus.luessing@xxxxxxxxx are queue-5.15/batman-adv-mcast-don-t-send-link-local-multicast-to-mcast-routers.patch