nl80211: Require auth type for NL80211_CMD_AUTHENTICATE

NL80211_ATTR_AUTH_TYPE is a required parameter for
NL80211_CMD_AUTHENTICATE. We are currently (by chance) defaulting to
open system authentication if the attribute is not specified. It is
better to just reject the invalid command.
Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/nl80211.c

@@ -2752,6 +2752,9 @@ static int nl80211_authenticate(struct sk_buff *skb, struct genl_info *info)
 	if (!info->attrs[NL80211_ATTR_MAC])
 		return -EINVAL;
 
+	if (!info->attrs[NL80211_ATTR_AUTH_TYPE])
+		return -EINVAL;
+
 	rtnl_lock();
 
 	err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2798,14 +2801,11 @@ static int nl80211_authenticate(struct sk_buff *skb, struct genl_info *info)
 		req.ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
 	}
 
-	if (info->attrs[NL80211_ATTR_AUTH_TYPE]) {
-		req.auth_type =
-			nla_get_u32(info->attrs[NL80211_ATTR_AUTH_TYPE]);
+	req.auth_type = nla_get_u32(info->attrs[NL80211_ATTR_AUTH_TYPE]);
 	if (!nl80211_valid_auth_type(req.auth_type)) {
 		err = -EINVAL;
 		goto out;
 	}
-	}
 
 	err = drv->ops->auth(&drv->wiphy, dev, &req);