cfg80211: support reloading regulatory database

If the regulatory database is loaded, and then updated, it may
be necessary to reload it. Add an nl80211 command to do this.

Note that this just reloads the database, it doesn't re-apply
the rules from it immediately.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/uapi/linux/nl80211.h

@@ -990,6 +990,8 @@
  *	&NL80211_CMD_CONNECT or &NL80211_CMD_ROAM. If the 4 way handshake failed
  *	&NL80211_CMD_DISCONNECT should be indicated instead.
  *
+ * @NL80211_CMD_RELOAD_REGDB: Request that the regdb firmware file is reloaded.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1194,6 +1196,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_PORT_AUTHORIZED,
 
+	NL80211_CMD_RELOAD_REGDB,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

net/wireless/nl80211.c

@@ -5678,6 +5678,11 @@ static int nl80211_req_set_reg(struct sk_buff *skb, struct genl_info *info)
 	}
 }
 
+static int nl80211_reload_regdb(struct sk_buff *skb, struct genl_info *info)
+{
+	return reg_reload_regdb();
+}
+
 static int nl80211_get_mesh_config(struct sk_buff *skb,
 				   struct genl_info *info)
 {
@@ -12708,6 +12713,12 @@ static const struct genl_ops nl80211_ops[] = {
 		.policy = nl80211_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
+	{
+		.cmd = NL80211_CMD_RELOAD_REGDB,
+		.doit = nl80211_reload_regdb,
+		.policy = nl80211_policy,
+		.flags = GENL_ADMIN_PERM,
+	},
 	{
 		.cmd = NL80211_CMD_GET_MESH_CONFIG,
 		.doit = nl80211_get_mesh_config,

net/wireless/reg.c

@@ -781,6 +781,8 @@ static int query_regdb(const char *alpha2)
 	const struct fwdb_header *hdr = regdb;
 	const struct fwdb_country *country;
 
+	ASSERT_RTNL();
+
 	if (IS_ERR(regdb))
 		return PTR_ERR(regdb);
 
@@ -796,41 +798,47 @@ static int query_regdb(const char *alpha2)
 
 static void regdb_fw_cb(const struct firmware *fw, void *context)
 {
+	int set_error = 0;
+	bool restore = true;
 	void *db;
 
 	if (!fw) {
 		pr_info("failed to load regulatory.db\n");
-		regdb = ERR_PTR(-ENODATA);
-		goto restore;
-	}
-
-	if (!valid_regdb(fw->data, fw->size)) {
+		set_error = -ENODATA;
+	} else if (!valid_regdb(fw->data, fw->size)) {
 		pr_info("loaded regulatory.db is malformed\n");
-		release_firmware(fw);
-		regdb = ERR_PTR(-EINVAL);
-		goto restore;
+		set_error = -EINVAL;
 	}
 
-	db = kmemdup(fw->data, fw->size, GFP_KERNEL);
-	release_firmware(fw);
+	rtnl_lock();
+	if (WARN_ON(regdb && !IS_ERR(regdb))) {
+		/* just restore and free new db */
+	} else if (set_error) {
+		regdb = ERR_PTR(set_error);
+	} else if (fw) {
+		db = kmemdup(fw->data, fw->size, GFP_KERNEL);
+		if (db) {
+			regdb = db;
+			restore = context && query_regdb(context);
+		} else {
+			restore = true;
+		}
+	}
 
-	if (!db)
-		goto restore;
-	regdb = db;
+	if (restore)
+		restore_regulatory_settings(true);
 
-	if (query_regdb(context))
-		goto restore;
-	goto free;
- restore:
-	rtnl_lock();
-	restore_regulatory_settings(true);
 	rtnl_unlock();
- free:
+
 	kfree(context);
+
+	release_firmware(fw);
 }
 
 static int query_regdb_file(const char *alpha2)
 {
+	ASSERT_RTNL();
+
 	if (regdb)
 		return query_regdb(alpha2);
 
@@ -843,6 +851,38 @@ static int query_regdb_file(const char *alpha2)
 				       (void *)alpha2, regdb_fw_cb);
 }
 
+int reg_reload_regdb(void)
+{
+	const struct firmware *fw;
+	void *db;
+	int err;
+
+	err = request_firmware(&fw, "regulatory.db", &reg_pdev->dev);
+	if (err)
+		return err;
+
+	if (!valid_regdb(fw->data, fw->size)) {
+		err = -ENODATA;
+		goto out;
+	}
+
+	db = kmemdup(fw->data, fw->size, GFP_KERNEL);
+	if (!db) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	rtnl_lock();
+	if (!IS_ERR_OR_NULL(regdb))
+		kfree(regdb);
+	regdb = db;
+	rtnl_unlock();
+
+ out:
+	release_firmware(fw);
+	return err;
+}
+
 static bool reg_query_database(struct regulatory_request *request)
 {
 	/* query internal regulatory database (if it exists) */

net/wireless/reg.h

@@ -179,4 +179,10 @@ void regulatory_propagate_dfs_state(struct wiphy *wiphy,
  * @wiphy2 - wiphy it's dfs_region to be checked against that of wiphy1
  */
 bool reg_dfs_domain_same(struct wiphy *wiphy1, struct wiphy *wiphy2);
+
+/**
+ * reg_reload_regdb - reload the regulatory.db firmware file
+ */
+int reg_reload_regdb(void);
+
 #endif  /* __NET_WIRELESS_REG_H */