The following commit has been merged in the batadv/net-next branch: commit 62accacc8d5e8d2d5730a47b9e1b738d224e1b85 Author: Sven Eckelmann sven@narfation.org Date: Mon Dec 16 19:37:12 2024 +0100

batman-adv: Map VID 0 to untagged TT VLAN

VID 0 is not a valid VLAN according to "802.1Q-2011" "Table 9-2—Reserved VID values". It is only used to indicate "priority tag" frames which only contain priority information and no VID.

The 8021q is also redirecting the priority tagged frames to the underlying interface since commit ad1afb003939 ("vlan_dev: VLAN 0 should be treated as "no vlan tag" (802.1p packet)"). But at the same time, it automatically adds the VID 0 to all devices to ensure that VID 0 is in the allowed list of the HW filter. This resulted in a VLAN 0 which was always announced in OGM messages.

batman-adv should therefore not create a new batadv_softif_vlan for VID 0 and handle all VID 0 related frames using the "untagged" global/local translation tables.

Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c index 8e0f44c71696f..333e947afcce7 100644 --- a/net/batman-adv/main.c +++ b/net/batman-adv/main.c @@ -637,6 +637,13 @@ unsigned short batadv_get_vid(struct sk_buff *skb, size_t header_len)

vhdr = (struct vlan_ethhdr *)(skb->data + header_len); vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK; + + /* VID 0 is only used to indicate "priority tag" frames which only + * contain priority information and no VID. + */ + if (vid == 0) + return BATADV_NO_FLAGS; + vid |= BATADV_VLAN_HAS_TAG;

return vid; diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 5666c268cead2..822d788a5f86b 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -637,6 +637,14 @@ static int batadv_interface_add_vid(struct net_device *dev, __be16 proto, if (proto != htons(ETH_P_8021Q)) return -EINVAL;

+ /* VID 0 is only used to indicate "priority tag" frames which only + * contain priority information and no VID. No management structures + * should be created for this VID and it should be handled like an + * untagged frame. + */ + if (vid == 0) + return 0; + vid |= BATADV_VLAN_HAS_TAG;

/* if a new vlan is getting created and it already exists, it means that @@ -684,6 +692,12 @@ static int batadv_interface_kill_vid(struct net_device *dev, __be16 proto, if (proto != htons(ETH_P_8021Q)) return -EINVAL;

+ /* "priority tag" frames are handled like "untagged" frames + * and no softif_vlan needs to be destroyed + */ + if (vid == 0) + return 0; + vlan = batadv_softif_vlan_get(bat_priv, vid | BATADV_VLAN_HAS_TAG); if (!vlan) return -ENOENT;