wifi: mac80211: send extended MLD capa/ops if AP has it

Currently the code only sends extended MLD capa/ops in
strict mode, but if the AP has it then it should also
be able to parse it. There could be cases where the AP
doesn't have it but we would want to advertise it (e.g.
if the AP supports nothing but we want to have BTM.),
but given the broken deployed APs out there right now
this is the best we can do.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250609213232.c9b8b3a6ca77.I1153d4283d1fbb9e5db60e7b939cc133a6345db5@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 45 insertions, 9 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 75dfbb06dff2..1bedd8d6e891 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1939,14 +1939,7 @@ ieee80211_assoc_add_ml_elem(struct ieee80211_sub_if_data *sdata,
 	}
 	skb_put_data(skb, &mld_capa_ops, sizeof(mld_capa_ops));
 
-	/* Many APs have broken parsing of the extended MLD capa/ops field,
-	 * dropping (re-)association request frames or replying with association
-	 * response with a failure status if it's present. Without a clear
-	 * indication as to whether the AP supports parsing this field or not do
-	 * not include it in the common information unless strict mode is set.
-	 */
-	if (ieee80211_hw_check(&local->hw, STRICT) &&
-	    assoc_data->ext_mld_capa_ops) {
+	if (assoc_data->ext_mld_capa_ops) {
 		ml_elem->control |=
 			cpu_to_le16(IEEE80211_MLC_BASIC_PRES_EXT_MLD_CAPA_OP);
 		common->len += 2;
@@ -9357,6 +9350,39 @@ out_rcu:
 	return err;
 }
 
+static bool
+ieee80211_mgd_assoc_bss_has_mld_ext_capa_ops(struct cfg80211_assoc_request *req)
+{
+	const struct cfg80211_bss_ies *ies;
+	struct cfg80211_bss *bss;
+	const struct element *ml;
+
+	/* not an MLO connection if link_id < 0, so irrelevant */
+	if (req->link_id < 0)
+		return false;
+
+	bss = req->links[req->link_id].bss;
+
+	guard(rcu)();
+	ies = rcu_dereference(bss->ies);
+	for_each_element_extid(ml, WLAN_EID_EXT_EHT_MULTI_LINK,
+			       ies->data, ies->len) {
+		const struct ieee80211_multi_link_elem *mle;
+
+		if (!ieee80211_mle_type_ok(ml->data + 1,
+					   IEEE80211_ML_CONTROL_TYPE_BASIC,
+					   ml->datalen - 1))
+			continue;
+
+		mle = (void *)(ml->data + 1);
+		if (mle->control & cpu_to_le16(IEEE80211_MLC_BASIC_PRES_EXT_MLD_CAPA_OP))
+			return true;
+	}
+
+	return false;
+
+}
+
 int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 			struct cfg80211_assoc_request *req)
 {
@@ -9409,7 +9435,17 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 	else
 		memcpy(assoc_data->ap_addr, cbss->bssid, ETH_ALEN);
 
-	assoc_data->ext_mld_capa_ops = cpu_to_le16(req->ext_mld_capa_ops);
+	/*
+	 * Many APs have broken parsing of the extended MLD capa/ops field,
+	 * dropping (re-)association request frames or replying with association
+	 * response with a failure status if it's present.
+	 * Set our value from the userspace request only in strict mode or if
+	 * the AP also had that field present.
+	 */
+	if (ieee80211_hw_check(&local->hw, STRICT) ||
+	    ieee80211_mgd_assoc_bss_has_mld_ext_capa_ops(req))
+		assoc_data->ext_mld_capa_ops =
+			cpu_to_le16(req->ext_mld_capa_ops);
 
 	if (ifmgd->associated) {
 		u8 frame_buf[IEEE80211_DEAUTH_FRAME_LEN];