cfg80211: add regulatory hint disconnect support

This adds a new regulatory hint to be used when we know all
devices have been disconnected and idle. This can happen
when we suspend, for instance. When we disconnect we can
no longer assume the same regulatory rules learned from
a country IE or beacon hints are applicable so restore
regulatory settings to an initial state.

Since driver hints are cached on the wiphy that called
the hint, those hints are not reproduced onto cfg80211
as the wiphy will respect its own wiphy->regd regardless.

Signed-off-by: Luis R. Rodriguez <[email protected]>
Signed-off-by: John W. Linville <[email protected]>

include/net/regulatory.h

@@ -39,6 +39,7 @@ enum environment_cap {
  * 	00 - World regulatory domain
  * 	99 - built by driver but a specific alpha2 cannot be determined
  * 	98 - result of an intersection between two regulatory domains
+ *	97 - regulatory domain has not yet been configured
  * @intersect: indicates whether the wireless core should intersect
  * 	the requested regulatory domain with the presently set regulatory
  * 	domain.

net/wireless/reg.c

@@ -134,6 +134,7 @@ static const struct ieee80211_regdomain *cfg80211_world_regdom =
 	&world_regdom;
 
 static char *ieee80211_regdom = "00";
+static char user_alpha2[2];
 
 module_param(ieee80211_regdom, charp, 0444);
 MODULE_PARM_DESC(ieee80211_regdom, "IEEE 802.11 regulatory domain code");
@@ -252,6 +253,27 @@ static bool regdom_changes(const char *alpha2)
 	return true;
 }
 
+/*
+ * The NL80211_REGDOM_SET_BY_USER regdom alpha2 is cached, this lets
+ * you know if a valid regulatory hint with NL80211_REGDOM_SET_BY_USER
+ * has ever been issued.
+ */
+static bool is_user_regdom_saved(void)
+{
+	if (user_alpha2[0] == '9' && user_alpha2[1] == '7')
+		return false;
+
+	/* This would indicate a mistake on the design */
+	if (WARN((!is_world_regdom(user_alpha2) &&
+		  !is_an_alpha2(user_alpha2)),
+		 "Unexpected user alpha2: %c%c\n",
+		 user_alpha2[0],
+	         user_alpha2[1]))
+		return false;
+
+	return true;
+}
+
 /**
  * country_ie_integrity_changes - tells us if the country IE has changed
  * @checksum: checksum of country IE of fields we are interested in
@@ -1646,7 +1668,7 @@ static int ignore_request(struct wiphy *wiphy,
 
 	switch (pending_request->initiator) {
 	case NL80211_REGDOM_SET_BY_CORE:
-		return -EINVAL;
+		return 0;
 	case NL80211_REGDOM_SET_BY_COUNTRY_IE:
 
 		last_wiphy = wiphy_idx_to_wiphy(last_request->wiphy_idx);
@@ -1785,6 +1807,11 @@ static int __regulatory_hint(struct wiphy *wiphy,
 
 	pending_request = NULL;
 
+	if (last_request->initiator == NL80211_REGDOM_SET_BY_USER) {
+		user_alpha2[0] = last_request->alpha2[0];
+		user_alpha2[1] = last_request->alpha2[1];
+	}
+
 	/* When r == REG_INTERSECT we do need to call CRDA */
 	if (r < 0) {
 		/*
@@ -1904,12 +1931,16 @@ static void queue_regulatory_request(struct regulatory_request *request)
 	schedule_work(&reg_work);
 }
 
-/* Core regulatory hint -- happens once during cfg80211_init() */
+/*
+ * Core regulatory hint -- happens during cfg80211_init()
+ * and when we restore regulatory settings.
+ */
 static int regulatory_hint_core(const char *alpha2)
 {
 	struct regulatory_request *request;
 
-	BUG_ON(last_request);
+	kfree(last_request);
+	last_request = NULL;
 
 	request = kzalloc(sizeof(struct regulatory_request),
 			  GFP_KERNEL);
@@ -2107,6 +2138,123 @@ void regulatory_hint_11d(struct wiphy *wiphy,
 	mutex_unlock(&reg_mutex);
 }
 
+static void restore_alpha2(char *alpha2, bool reset_user)
+{
+	/* indicates there is no alpha2 to consider for restoration */
+	alpha2[0] = '9';
+	alpha2[1] = '7';
+
+	/* The user setting has precedence over the module parameter */
+	if (is_user_regdom_saved()) {
+		/* Unless we're asked to ignore it and reset it */
+		if (reset_user) {
+			REG_DBG_PRINT("cfg80211: Restoring regulatory settings "
+			       "including user preference\n");
+			user_alpha2[0] = '9';
+			user_alpha2[1] = '7';
+
+			/*
+			 * If we're ignoring user settings, we still need to
+			 * check the module parameter to ensure we put things
+			 * back as they were for a full restore.
+			 */
+			if (!is_world_regdom(ieee80211_regdom)) {
+				REG_DBG_PRINT("cfg80211: Keeping preference on "
+				       "module parameter ieee80211_regdom: %c%c\n",
+				       ieee80211_regdom[0],
+				       ieee80211_regdom[1]);
+				alpha2[0] = ieee80211_regdom[0];
+				alpha2[1] = ieee80211_regdom[1];
+			}
+		} else {
+			REG_DBG_PRINT("cfg80211: Restoring regulatory settings "
+			       "while preserving user preference for: %c%c\n",
+			       user_alpha2[0],
+			       user_alpha2[1]);
+			alpha2[0] = user_alpha2[0];
+			alpha2[1] = user_alpha2[1];
+		}
+	} else if (!is_world_regdom(ieee80211_regdom)) {
+		REG_DBG_PRINT("cfg80211: Keeping preference on "
+		       "module parameter ieee80211_regdom: %c%c\n",
+		       ieee80211_regdom[0],
+		       ieee80211_regdom[1]);
+		alpha2[0] = ieee80211_regdom[0];
+		alpha2[1] = ieee80211_regdom[1];
+	} else
+		REG_DBG_PRINT("cfg80211: Restoring regulatory settings\n");
+}
+
+/*
+ * Restoring regulatory settings involves ingoring any
+ * possibly stale country IE information and user regulatory
+ * settings if so desired, this includes any beacon hints
+ * learned as we could have traveled outside to another country
+ * after disconnection. To restore regulatory settings we do
+ * exactly what we did at bootup:
+ *
+ *   - send a core regulatory hint
+ *   - send a user regulatory hint if applicable
+ *
+ * Device drivers that send a regulatory hint for a specific country
+ * keep their own regulatory domain on wiphy->regd so that does does
+ * not need to be remembered.
+ */
+static void restore_regulatory_settings(bool reset_user)
+{
+	char alpha2[2];
+	struct reg_beacon *reg_beacon, *btmp;
+
+	mutex_lock(&cfg80211_mutex);
+	mutex_lock(&reg_mutex);
+
+	reset_regdomains();
+	restore_alpha2(alpha2, reset_user);
+
+	/* Clear beacon hints */
+	spin_lock_bh(&reg_pending_beacons_lock);
+	if (!list_empty(&reg_pending_beacons)) {
+		list_for_each_entry_safe(reg_beacon, btmp,
+					 &reg_pending_beacons, list) {
+			list_del(&reg_beacon->list);
+			kfree(reg_beacon);
+		}
+	}
+	spin_unlock_bh(&reg_pending_beacons_lock);
+
+	if (!list_empty(&reg_beacon_list)) {
+		list_for_each_entry_safe(reg_beacon, btmp,
+					 &reg_beacon_list, list) {
+			list_del(&reg_beacon->list);
+			kfree(reg_beacon);
+		}
+	}
+
+	/* First restore to the basic regulatory settings */
+	cfg80211_regdomain = cfg80211_world_regdom;
+
+	mutex_unlock(&reg_mutex);
+	mutex_unlock(&cfg80211_mutex);
+
+	regulatory_hint_core(cfg80211_regdomain->alpha2);
+
+	/*
+	 * This restores the ieee80211_regdom module parameter
+	 * preference or the last user requested regulatory
+	 * settings, user regulatory settings takes precedence.
+	 */
+	if (is_an_alpha2(alpha2))
+		regulatory_hint_user(user_alpha2);
+}
+
+
+void regulatory_hint_disconnect(void)
+{
+	REG_DBG_PRINT("cfg80211: All devices are disconnected, going to "
+		      "restore regulatory settings\n");
+	restore_regulatory_settings(false);
+}
+
 static bool freq_is_chan_12_13_14(u16 freq)
 {
 	if (freq == ieee80211_channel_to_frequency(12) ||
@@ -2496,6 +2644,9 @@ int regulatory_init(void)
 
 	cfg80211_regdomain = cfg80211_world_regdom;
 
+	user_alpha2[0] = '9';
+	user_alpha2[1] = '7';
+
 	/* We always try to get an update for the static regdomain */
 	err = regulatory_hint_core(cfg80211_regdomain->alpha2);
 	if (err) {

net/wireless/reg.h

@@ -63,4 +63,22 @@ void regulatory_hint_11d(struct wiphy *wiphy,
 			 u8 *country_ie,
 			 u8 country_ie_len);
 
+/**
+ * regulatory_hint_disconnect - informs all devices have been disconneted
+ *
+ * Regulotory rules can be enhanced further upon scanning and upon
+ * connection to an AP. These rules become stale if we disconnect
+ * and go to another country, whether or not we suspend and resume.
+ * If we suspend, go to another country and resume we'll automatically
+ * get disconnected shortly after resuming and things will be reset as well.
+ * This routine is a helper to restore regulatory settings to how they were
+ * prior to our first connect attempt. This includes ignoring country IE and
+ * beacon regulatory hints. The ieee80211_regdom module parameter will always
+ * be respected but if a user had set the regulatory domain that will take
+ * precedence.
+ *
+ * Must be called from process context.
+ */
+void regulatory_hint_disconnect(void);
+
 #endif  /* __NET_WIRELESS_REG_H */

net/wireless/sme.c

@@ -34,6 +34,44 @@ struct cfg80211_conn {
 	bool auto_auth, prev_bssid_valid;
 };
 
+bool cfg80211_is_all_idle(void)
+{
+	struct cfg80211_registered_device *rdev;
+	struct wireless_dev *wdev;
+	bool is_all_idle = true;
+
+	mutex_lock(&cfg80211_mutex);
+
+	/*
+	 * All devices must be idle as otherwise if you are actively
+	 * scanning some new beacon hints could be learned and would
+	 * count as new regulatory hints.
+	 */
+	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
+		cfg80211_lock_rdev(rdev);
+		list_for_each_entry(wdev, &rdev->netdev_list, list) {
+			wdev_lock(wdev);
+			if (wdev->sme_state != CFG80211_SME_IDLE)
+				is_all_idle = false;
+			wdev_unlock(wdev);
+		}
+		cfg80211_unlock_rdev(rdev);
+	}
+
+	mutex_unlock(&cfg80211_mutex);
+
+	return is_all_idle;
+}
+
+static void disconnect_work(struct work_struct *work)
+{
+	if (!cfg80211_is_all_idle())
+		return;
+
+	regulatory_hint_disconnect();
+}
+
+static DECLARE_WORK(cfg80211_disconnect_work, disconnect_work);
 
 static int cfg80211_conn_scan(struct wireless_dev *wdev)
 {
@@ -658,6 +696,8 @@ void __cfg80211_disconnected(struct net_device *dev, const u8 *ie,
 	wireless_send_event(dev, SIOCGIWAP, &wrqu, NULL);
 	wdev->wext.connect.ssid_len = 0;
 #endif
+
+	schedule_work(&cfg80211_disconnect_work);
 }
 
 void cfg80211_disconnected(struct net_device *dev, u16 reason,