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>

8 files changed, 32 insertions, 14 deletions

diff --git a/net/wireless/ap.c b/net/wireless/ap.c
index 4760d6554e62..68602be07cc1 100644
--- a/net/wireless/ap.c
+++ b/net/wireless/ap.c
@@ -27,7 +27,7 @@ static int __cfg80211_stop_ap(struct cfg80211_registered_device *rdev,
         err = rdev_stop_ap(rdev, dev);
         if (!err) {
                 wdev->beacon_interval = 0;
-                wdev->channel = NULL;
+                memset(&wdev->chandef, 0, sizeof(wdev->chandef));
                 wdev->ssid_len = 0;
                 rdev_set_qos_map(rdev, dev, NULL);
                 nl80211_send_ap_stopped(wdev);
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:
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 8a820f9c4a76..9895ab16c051 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -443,7 +443,8 @@ static inline unsigned int elapsed_jiffies_msecs(unsigned long start)
 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);
 
 int cfg80211_set_monitor_channel(struct cfg80211_registered_device *rdev,
                                  struct cfg80211_chan_def *chandef);
diff --git a/net/wireless/ibss.c b/net/wireless/ibss.c
index e37e39c29dfb..1470b90e438f 100644
--- a/net/wireless/ibss.c
+++ b/net/wireless/ibss.c
@@ -122,6 +122,7 @@ int __cfg80211_join_ibss(struct cfg80211_registered_device *rdev,
 
         wdev->ibss_fixed = params->channel_fixed;
         wdev->ibss_dfs_possible = params->userspace_handles_dfs;
+        wdev->chandef = params->chandef;
 #ifdef CONFIG_CFG80211_WEXT
         wdev->wext.ibss.chandef = params->chandef;
 #endif
@@ -205,6 +206,7 @@ static void __cfg80211_clear_ibss(struct net_device *dev, bool nowext)
 
         wdev->current_bss = NULL;
         wdev->ssid_len = 0;
+        memset(&wdev->chandef, 0, sizeof(wdev->chandef));
 #ifdef CONFIG_CFG80211_WEXT
         if (!nowext)
                 wdev->wext.ibss.ssid_len = 0;
diff --git a/net/wireless/mesh.c b/net/wireless/mesh.c
index 885862447b63..d42a3fcb2f67 100644
--- a/net/wireless/mesh.c
+++ b/net/wireless/mesh.c
@@ -195,7 +195,7 @@ int __cfg80211_join_mesh(struct cfg80211_registered_device *rdev,
         if (!err) {
                 memcpy(wdev->ssid, setup->mesh_id, setup->mesh_id_len);
                 wdev->mesh_id_len = setup->mesh_id_len;
-                wdev->channel = setup->chandef.chan;
+                wdev->chandef = setup->chandef;
         }
 
         return err;
@@ -244,7 +244,7 @@ int cfg80211_set_mesh_channel(struct cfg80211_registered_device *rdev,
                 err = rdev_libertas_set_mesh_channel(rdev, wdev->netdev,
                                                      chandef->chan);
                 if (!err)
-                        wdev->channel = chandef->chan;
+                        wdev->chandef = *chandef;
 
                 return err;
         }
@@ -276,7 +276,7 @@ static int __cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
         err = rdev_leave_mesh(rdev, dev);
         if (!err) {
                 wdev->mesh_id_len = 0;
-                wdev->channel = NULL;
+                memset(&wdev->chandef, 0, sizeof(wdev->chandef));
                 rdev_set_qos_map(rdev, dev, NULL);
         }
 
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 52cca05044a8..d47c9d127b1e 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -772,7 +772,7 @@ void cfg80211_cac_event(struct net_device *netdev,
         if (WARN_ON(!wdev->cac_started))
                 return;
 
-        if (WARN_ON(!wdev->channel))
+        if (WARN_ON(!wdev->chandef.chan))
                 return;
 
         switch (event) {
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 0a186013728c..be091ddd43a4 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3281,7 +3281,7 @@ static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
         if (!err) {
                 wdev->preset_chandef = params.chandef;
                 wdev->beacon_interval = params.beacon_interval;
-                wdev->channel = params.chandef.chan;
+                wdev->chandef = params.chandef;
                 wdev->ssid_len = params.ssid_len;
                 memcpy(wdev->ssid, params.ssid, wdev->ssid_len);
         }
@@ -5797,7 +5797,7 @@ static int nl80211_start_radar_detection(struct sk_buff *skb,
 
         err = rdev->ops->start_radar_detection(&rdev->wiphy, dev, &chandef);
         if (!err) {
-                wdev->channel = chandef.chan;
+                wdev->chandef = chandef;
                 wdev->cac_started = true;
                 wdev->cac_start_time = jiffies;
         }
@@ -11215,7 +11215,7 @@ void cfg80211_ch_switch_notify(struct net_device *dev,
                     wdev->iftype != NL80211_IFTYPE_MESH_POINT))
                 return;
 
-        wdev->channel = chandef->chan;
+        wdev->chandef = *chandef;
         wdev->preset_chandef = *chandef;
         nl80211_ch_switch_notify(rdev, dev, chandef, GFP_KERNEL);
 }
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 7526a4d8aa16..780b4546c9c7 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1357,7 +1357,7 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
                  */
                 mutex_lock_nested(&wdev_iter->mtx, 1);
                 __acquire(wdev_iter->mtx);
-                cfg80211_get_chan_state(wdev_iter, &ch, &chmode);
+                cfg80211_get_chan_state(wdev_iter, &ch, &chmode, &radar_detect);
                 wdev_unlock(wdev_iter);
 
                 switch (chmode) {