cfg80211: consider existing DFS interfaces

It was possible to break interface combinations in
the following way:

 combo 1: iftype = AP, num_ifaces = 2, num_chans = 2,
 combo 2: iftype = AP, num_ifaces = 1, num_chans = 1, radar = HT20

With the above interface combinations it was
possible to:

 step 1. start AP on DFS channel by matching combo 2
 step 2. start AP on non-DFS channel by matching combo 1

This was possible beacuse (step 2) did not consider
if other interfaces require radar detection.

The patch changes how cfg80211 tracks channels -
instead of channel itself now a complete chandef
is stored.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 78559b5bbd1f..f8ab7df1ab0d 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -642,7 +642,8 @@ int cfg80211_set_monitor_channel(struct cfg80211_registered_device *rdev,
 void
 cfg80211_get_chan_state(struct wireless_dev *wdev,
                         struct ieee80211_channel **chan,
-                        enum cfg80211_chan_mode *chanmode)
+                        enum cfg80211_chan_mode *chanmode,
+                        u8 *radar_detect)
 {
         *chan = NULL;
         *chanmode = CHAN_MODE_UNDEFINED;
@@ -660,6 +661,11 @@ cfg80211_get_chan_state(struct wireless_dev *wdev,
                                      !wdev->ibss_dfs_possible)
                                   ? CHAN_MODE_SHARED
                                   : CHAN_MODE_EXCLUSIVE;
+
+                        /* consider worst-case - IBSS can try to return to the
+                         * original user-specified channel as creator */
+                        if (wdev->ibss_dfs_possible)
+                                *radar_detect |= BIT(wdev->chandef.width);
                         return;
                 }
                 break;
@@ -674,17 +680,26 @@ cfg80211_get_chan_state(struct wireless_dev *wdev,
         case NL80211_IFTYPE_AP:
         case NL80211_IFTYPE_P2P_GO:
                 if (wdev->cac_started) {
-                        *chan = wdev->channel;
+                        *chan = wdev->chandef.chan;
                         *chanmode = CHAN_MODE_SHARED;
+                        *radar_detect |= BIT(wdev->chandef.width);
                 } else if (wdev->beacon_interval) {
-                        *chan = wdev->channel;
+                        *chan = wdev->chandef.chan;
                         *chanmode = CHAN_MODE_SHARED;
+
+                        if (cfg80211_chandef_dfs_required(wdev->wiphy,
+                                                          &wdev->chandef))
+                                *radar_detect |= BIT(wdev->chandef.width);
                 }
                 return;
         case NL80211_IFTYPE_MESH_POINT:
                 if (wdev->mesh_id_len) {
-                        *chan = wdev->channel;
+                        *chan = wdev->chandef.chan;
                         *chanmode = CHAN_MODE_SHARED;
+
+                        if (cfg80211_chandef_dfs_required(wdev->wiphy,
+                                                          &wdev->chandef))
+                                *radar_detect |= BIT(wdev->chandef.width);
                 }
                 return;
         case NL80211_IFTYPE_MONITOR: