wifi: cfg80211: add support for link id attribute in NL80211_CMD_DEL_STATION

Currently whenever NL80211_CMD_DEL_STATION command is called without any
MAC address, all stations present on that interface are flushed.
However with MLO there is a need to flush such stations only which are
using at least a particular link from the AP MLD interface.

For example - 2 GHz and 5 GHz are part of an AP MLD.
To this interface, following stations are connected -
   1. One non-EHT STA on 2 GHz link.
   2. One non-EHT STA on 5 GHz link.
   3. One Multi-Link STA having 2 GHz and 5 GHz as active links.

Now if currently, NL80211_CMD_DEL_STATION is issued by the 2 GHz link
without any MAC address, it would flush all station entries. However,
flushing of station entry #2 at least is not desireable since it
is connected to 5 GHz link alone.

Hence, add an option to pass link ID as well in the command so that if link
ID is passed, stations using that passed link ID alone would be flushed
and others will not.

So after this, station entries #1 and #3 alone would be flushed and #2 will
remain as it is.

Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
Link: https://msgid.link/20240205162952.1697646-2-quic_adisi@quicinc.com
[clarify documentation]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 23 insertions, 3 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e1106ae35e21d..5ca5457538109 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -7624,14 +7624,16 @@ static int nl80211_del_station(struct sk_buff *skb, struct genl_info *info)
 {
 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
 	struct net_device *dev = info->user_ptr[1];
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct station_del_parameters params;
+	int link_id = nl80211_link_id_or_invalid(info->attrs);
 
 	memset(&params, 0, sizeof(params));
 
 	if (info->attrs[NL80211_ATTR_MAC])
 		params.mac = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
-	switch (dev->ieee80211_ptr->iftype) {
+	switch (wdev->iftype) {
 	case NL80211_IFTYPE_AP:
 	case NL80211_IFTYPE_AP_VLAN:
 	case NL80211_IFTYPE_MESH_POINT:
@@ -7672,6 +7674,17 @@ static int nl80211_del_station(struct sk_buff *skb, struct genl_info *info)
 		params.reason_code = WLAN_REASON_PREV_AUTH_NOT_VALID;
 	}
 
+	/* Link ID not expected in case of non-ML operation */
+	if (!wdev->valid_links && link_id != -1)
+		return -EINVAL;
+
+	/* If given, a valid link ID should be passed during MLO */
+	if (wdev->valid_links && link_id >= 0 &&
+	    !(wdev->valid_links & BIT(link_id)))
+		return -EINVAL;
+
+	params.link_id = link_id;
+
 	return rdev_del_station(rdev, dev, &params);
 }
 
@@ -16773,6 +16786,10 @@ static const struct genl_small_ops nl80211_small_ops[] = {
 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = nl80211_del_station,
 		.flags = GENL_UNS_ADMIN_PERM,
+		/* cannot use NL80211_FLAG_MLO_VALID_LINK_ID, depends on
+		 * whether MAC address is passed or not. If MAC address is
+		 * passed, then even during MLO, link ID is not required.
+		 */
 		.internal_flags = IFLAGS(NL80211_FLAG_NEED_NETDEV_UP),
 	},
 	{
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 194ea24717177..361331c29116f 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -867,6 +867,7 @@ DECLARE_EVENT_CLASS(station_del,
 		MAC_ENTRY(sta_mac)
 		__field(u8, subtype)
 		__field(u16, reason_code)
+		__field(int, link_id)
 	),
 	TP_fast_assign(
 		WIPHY_ASSIGN;
@@ -874,11 +875,13 @@ DECLARE_EVENT_CLASS(station_del,
 		MAC_ASSIGN(sta_mac, params->mac);
 		__entry->subtype = params->subtype;
 		__entry->reason_code = params->reason_code;
+		__entry->link_id = params->link_id;
 	),
 	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", station mac: %pM"
-		  ", subtype: %u, reason_code: %u",
+		  ", subtype: %u, reason_code: %u, link_id: %d",
 		  WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->sta_mac,
-		  __entry->subtype, __entry->reason_code)
+		  __entry->subtype, __entry->reason_code,
+		  __entry->link_id)
 );
 
 DEFINE_EVENT(station_del, rdev_del_station,