cfg80211: check radar interface combinations

To ease further DFS development regarding interface combinations, use
the interface combinations structure to test for radar capabilities.
Drivers can specify which channel widths they support, and in which
modes. Right now only a single AP interface is allowed, but as the
DFS code evolves other combinations can be enabled.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 55 insertions, 8 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 747dd93..0e702cd 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -382,8 +382,11 @@ static int wiphy_verify_combinations(struct wiphy *wiphy)
 
 		c = &wiphy->iface_combinations[i];
 
-		/* Combinations with just one interface aren't real */
-		if (WARN_ON(c->max_interfaces < 2))
+		/*
+		 * Combinations with just one interface aren't real,
+		 * however we make an exception for DFS.
+		 */
+		if (WARN_ON((c->max_interfaces < 2) && !c->radar_detect_widths))
 			return -EINVAL;
 
 		/* Need at least one channel */
@@ -398,6 +401,11 @@ static int wiphy_verify_combinations(struct wiphy *wiphy)
 				CFG80211_MAX_NUM_DIFFERENT_CHANNELS))
 			return -EINVAL;
 
+		/* DFS only works on one channel. */
+		if (WARN_ON(c->radar_detect_widths &&
+			    (c->num_different_channels > 1)))
+			return -EINVAL;
+
 		if (WARN_ON(!c->n_limits))
 			return -EINVAL;
 
diff --git a/net/wireless/core.h b/net/wireless/core.h
index f342267..8396f76 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -425,7 +425,8 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 				 struct wireless_dev *wdev,
 				 enum nl80211_iftype iftype,
 				 struct ieee80211_channel *chan,
-				 enum cfg80211_chan_mode chanmode);
+				 enum cfg80211_chan_mode chanmode,
+				 u8 radar_detect);
 
 static inline int
 cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
@@ -433,7 +434,7 @@ cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
 			      enum nl80211_iftype iftype)
 {
 	return cfg80211_can_use_iftype_chan(rdev, wdev, iftype, NULL,
-					    CHAN_MODE_UNDEFINED);
+					    CHAN_MODE_UNDEFINED, 0);
 }
 
 static inline int
@@ -450,7 +451,7 @@ cfg80211_can_use_chan(struct cfg80211_registered_device *rdev,
 		      enum cfg80211_chan_mode chanmode)
 {
 	return cfg80211_can_use_iftype_chan(rdev, wdev, wdev->iftype,
-					    chan, chanmode);
+					    chan, chanmode, 0);
 }
 
 void
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index df82a5c..33de803 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -856,6 +856,9 @@ static int nl80211_put_iface_combinations(struct wiphy *wiphy,
 		    nla_put_u32(msg, NL80211_IFACE_COMB_MAXNUM,
 				c->max_interfaces))
 			goto nla_put_failure;
+		if (nla_put_u32(msg, NL80211_IFACE_COMB_RADAR_DETECT_WIDTHS,
+				c->radar_detect_widths))
+			goto nla_put_failure;
 
 		nla_nest_end(msg, nl_combi);
 	}
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 16d76a8..1c2795d 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1184,7 +1184,8 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 				 struct wireless_dev *wdev,
 				 enum nl80211_iftype iftype,
 				 struct ieee80211_channel *chan,
-				 enum cfg80211_chan_mode chanmode)
+				 enum cfg80211_chan_mode chanmode,
+				 u8 radar_detect)
 {
 	struct wireless_dev *wdev_iter;
 	u32 used_iftypes = BIT(iftype);
@@ -1195,14 +1196,45 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 	enum cfg80211_chan_mode chmode;
 	int num_different_channels = 0;
 	int total = 1;
+	bool radar_required;
 	int i, j;
 
 	ASSERT_RTNL();
 	lockdep_assert_held(&rdev->devlist_mtx);
 
+	if (WARN_ON(hweight32(radar_detect) > 1))
+		return -EINVAL;
+
+	switch (iftype) {
+	case NL80211_IFTYPE_ADHOC:
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_AP_VLAN:
+	case NL80211_IFTYPE_MESH_POINT:
+	case NL80211_IFTYPE_P2P_GO:
+	case NL80211_IFTYPE_WDS:
+		radar_required = !!(chan->flags & IEEE80211_CHAN_RADAR);
+		break;
+	case NL80211_IFTYPE_P2P_CLIENT:
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_MONITOR:
+		radar_required = false;
+		break;
+	case NL80211_IFTYPE_P2P_DEVICE:
+	case NUM_NL80211_IFTYPES:
+	case NL80211_IFTYPE_UNSPECIFIED:
+	default:
+		return -EINVAL;
+	}
+
+	if (radar_required && !radar_detect)
+		return -EINVAL;
+
 	/* Always allow software iftypes */
-	if (rdev->wiphy.software_iftypes & BIT(iftype))
+	if (rdev->wiphy.software_iftypes & BIT(iftype)) {
+		if (radar_detect)
+			return -EINVAL;
 		return 0;
+	}
 
 	memset(num, 0, sizeof(num));
 	memset(used_channels, 0, sizeof(used_channels));
@@ -1275,7 +1307,7 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 		used_iftypes |= BIT(wdev_iter->iftype);
 	}
 
-	if (total == 1)
+	if (total == 1 && !radar_detect)
 		return 0;
 
 	for (i = 0; i < rdev->wiphy.n_iface_combinations; i++) {
@@ -1308,6 +1340,9 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 			}
 		}
 
+		if (radar_detect && !(c->radar_detect_widths & radar_detect))
+			goto cont;
+
 		/*
 		 * Finally check that all iftypes that we're currently
 		 * using are actually part of this combination. If they