cfg80211: leave invalid channels on regdomain change

When the regulatory settings change, some channels might become invalid.
Disconnect interfaces acting on these channels, after giving userspace
code a grace period to leave them.

This mode is currently opt-in, and not all interface operating modes are
supported for regulatory-enforcement checks. A wiphy that wishes to use
the new enforcement code must specify an appropriate regulatory flag,
and all its supported interface modes must be supported by the checking
code.

Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Reviewed-by: Luis R. Rodriguez <mcgrof@suse.com>
[fix some indentation, typos]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -56,6 +56,7 @@
 #include <net/cfg80211.h>
 #include "core.h"
 #include "reg.h"
+#include "rdev-ops.h"
 #include "regdb.h"
 #include "nl80211.h"
 
@@ -66,6 +67,12 @@
 #define REG_DBG_PRINT(args...)
 #endif
 
+/*
+ * Grace period we give before making sure all current interfaces reside on
+ * channels allowed by the current regulatory domain.
+ */
+#define REG_ENFORCE_GRACE_MS 60000
+
 /**
  * enum reg_request_treatment - regulatory request treatment
  *
@@ -210,6 +217,9 @@ struct reg_beacon {
 	struct ieee80211_channel chan;
 };
 
+static void reg_check_chans_work(struct work_struct *work);
+static DECLARE_DELAYED_WORK(reg_check_chans, reg_check_chans_work);
+
 static void reg_todo(struct work_struct *work);
 static DECLARE_WORK(reg_work, reg_todo);
 
@@ -1518,6 +1528,96 @@ static void reg_call_notifier(struct wiphy *wiphy,
 		wiphy->reg_notifier(wiphy, request);
 }
 
+static bool reg_wdev_chan_valid(struct wiphy *wiphy, struct wireless_dev *wdev)
+{
+	struct ieee80211_channel *ch;
+	struct cfg80211_chan_def chandef;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+	bool ret = true;
+
+	wdev_lock(wdev);
+
+	if (!wdev->netdev || !netif_running(wdev->netdev))
+		goto out;
+
+	switch (wdev->iftype) {
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_P2P_GO:
+		if (!wdev->beacon_interval)
+			goto out;
+
+		ret = cfg80211_reg_can_beacon(wiphy,
+					      &wdev->chandef, wdev->iftype);
+		break;
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_P2P_CLIENT:
+	case NL80211_IFTYPE_ADHOC:
+		if (!wdev->current_bss ||
+		    !wdev->current_bss->pub.channel)
+			goto out;
+
+		ch = wdev->current_bss->pub.channel;
+		if (rdev->ops->get_channel &&
+		    !rdev_get_channel(rdev, wdev, &chandef))
+			ret = cfg80211_chandef_usable(wiphy, &chandef,
+						      IEEE80211_CHAN_DISABLED);
+		else
+			ret = !(ch->flags & IEEE80211_CHAN_DISABLED);
+		break;
+	case NL80211_IFTYPE_MONITOR:
+	case NL80211_IFTYPE_AP_VLAN:
+	case NL80211_IFTYPE_P2P_DEVICE:
+		/* no enforcement required */
+		break;
+	default:
+		/* others not implemented for now */
+		WARN_ON(1);
+		break;
+	}
+
+out:
+	wdev_unlock(wdev);
+	return ret;
+}
+
+static void reg_leave_invalid_chans(struct wiphy *wiphy)
+{
+	struct wireless_dev *wdev;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+
+	ASSERT_RTNL();
+
+	list_for_each_entry(wdev, &rdev->wdev_list, list)
+		if (!reg_wdev_chan_valid(wiphy, wdev))
+			cfg80211_leave(rdev, wdev);
+}
+
+static void reg_check_chans_work(struct work_struct *work)
+{
+	struct cfg80211_registered_device *rdev;
+
+	REG_DBG_PRINT("Verifying active interfaces after reg change\n");
+	rtnl_lock();
+
+	list_for_each_entry(rdev, &cfg80211_rdev_list, list)
+		if (!(rdev->wiphy.regulatory_flags &
+		      REGULATORY_IGNORE_STALE_KICKOFF))
+			reg_leave_invalid_chans(&rdev->wiphy);
+
+	rtnl_unlock();
+}
+
+static void reg_check_channels(void)
+{
+	/*
+	 * Give usermode a chance to do something nicer (move to another
+	 * channel, orderly disconnection), before forcing a disconnection.
+	 */
+	mod_delayed_work(system_power_efficient_wq,
+			 &reg_check_chans,
+			 msecs_to_jiffies(REG_ENFORCE_GRACE_MS));
+}
+
 static void wiphy_update_regulatory(struct wiphy *wiphy,
 				    enum nl80211_reg_initiator initiator)
 {
@@ -1557,6 +1657,8 @@ static void update_all_wiphy_regulatory(enum nl80211_reg_initiator initiator)
 		wiphy = &rdev->wiphy;
 		wiphy_update_regulatory(wiphy, initiator);
 	}
+
+	reg_check_channels();
 }
 
 static void handle_channel_custom(struct wiphy *wiphy,
@@ -1976,8 +2078,10 @@ static void reg_process_hint(struct regulatory_request *reg_request)
 
 	/* This is required so that the orig_* parameters are saved */
 	if (treatment == REG_REQ_ALREADY_SET && wiphy &&
-	    wiphy->regulatory_flags & REGULATORY_STRICT_REG)
+	    wiphy->regulatory_flags & REGULATORY_STRICT_REG) {
 		wiphy_update_regulatory(wiphy, reg_request->initiator);
+		reg_check_channels();
+	}
 
 	return;
 
@@ -2858,6 +2962,7 @@ void regulatory_exit(void)
 
 	cancel_work_sync(&reg_work);
 	cancel_delayed_work_sync(&reg_timeout);
+	cancel_delayed_work_sync(&reg_check_chans);
 
 	/* Lock to suppress warnings */
 	rtnl_lock();