rfkill: allow toggling soft state in sysfs again

Apparently there actually _are_ tools that try to set
this in sysfs even though it wasn't supposed to be used
this way without claiming first. Guess what: now that
I've cleaned it all up it doesn't matter and we can
simply allow setting the soft-block state in sysfs.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-By: Darren Salt <linux@youmustbejoking.demon.co.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/rfkill/core.c

@@ -648,15 +648,26 @@ static ssize_t rfkill_state_store(struct device *dev,
 				  struct device_attribute *attr,
 				  const char *buf, size_t count)
 {
-	/*
-	 * The intention was that userspace can only take control over
-	 * a given device when/if rfkill-input doesn't control it due
-	 * to user_claim. Since user_claim is currently unsupported,
-	 * we never support changing the state from userspace -- this
-	 * can be implemented again later.
-	 */
+	struct rfkill *rfkill = to_rfkill(dev);
+	unsigned long state;
+	int err;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	err = strict_strtoul(buf, 0, &state);
+	if (err)
+		return err;
+
+	if (state != RFKILL_USER_STATE_SOFT_BLOCKED &&
+	    state != RFKILL_USER_STATE_UNBLOCKED)
+		return -EINVAL;
+
+	mutex_lock(&rfkill_global_mutex);
+	rfkill_set_block(rfkill, state == RFKILL_USER_STATE_SOFT_BLOCKED);
+	mutex_unlock(&rfkill_global_mutex);
 
-	return -EPERM;
+	return err ?: count;
 }
 
 static ssize_t rfkill_claim_show(struct device *dev,