mac80211: mesh: mark channel as unusable if a regulatory MESH CSA is received

In the Mesh Channel Switch Parameters (8.4.2.105) the reason is specified
to WLAN_REASON_MESH_CHAN_REGULATORY in the case that a regulatory
limitation was the cause for the switch. This means another station
detected a radar event.

Mark the channel as unusable if this happens.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
[sw: style cleanup, rebase]
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1440,6 +1440,7 @@ struct ieee80211_csa_ie {
 	u8 count;
 	u8 ttl;
 	u16 pre_value;
+	u16 reason_code;
 };
 
 /* Parsed Information Elements */

net/mac80211/mesh.c

@@ -916,6 +916,21 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
 	ieee80211_configure_filter(local);
 }
 
+static void ieee80211_mesh_csa_mark_radar(struct ieee80211_sub_if_data *sdata)
+{
+	int err;
+
+	/* if the current channel is a DFS channel, mark the channel as
+	 * unavailable.
+	 */
+	err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
+					    &sdata->vif.bss_conf.chandef,
+					    NL80211_IFTYPE_MESH_POINT);
+	if (err > 0)
+		cfg80211_radar_event(sdata->local->hw.wiphy,
+				     &sdata->vif.bss_conf.chandef, GFP_ATOMIC);
+}
+
 static bool
 ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 				 struct ieee802_11_elems *elems, bool beacon)
@@ -954,6 +969,12 @@ ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 	if (err)
 		return false;
 
+	/* Mark the channel unavailable if the reason for the switch is
+	 * regulatory.
+	 */
+	if (csa_ie.reason_code == WLAN_REASON_MESH_CHAN_REGULATORY)
+		ieee80211_mesh_csa_mark_radar(sdata);
+
 	params.chandef = csa_ie.chandef;
 	params.count = csa_ie.count;
 

net/mac80211/spectmgmt.c

@@ -76,6 +76,11 @@ int ieee80211_parse_ch_switch_ie(struct ieee80211_sub_if_data *sdata,
 		csa_ie->mode = elems->mesh_chansw_params_ie->mesh_flags;
 		csa_ie->pre_value = le16_to_cpu(
 				elems->mesh_chansw_params_ie->mesh_pre_value);
+
+		if (elems->mesh_chansw_params_ie->mesh_flags &
+				WLAN_EID_CHAN_SWITCH_PARAM_REASON)
+			csa_ie->reason_code = le16_to_cpu(
+				elems->mesh_chansw_params_ie->mesh_reason);
 	}
 
 	new_freq = ieee80211_channel_to_frequency(new_chan_no, new_band);