luci-base: protect CBI forms with CSRF tokens

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

modules/luci-base/luasrc/dispatcher.lua

@@ -743,6 +743,15 @@ local function _cbi(self, ...)
 	local cbi = require "luci.cbi"
 	local tpl = require "luci.template"
 	local http = require "luci.http"
+	local disp = require "luci.dispatcher"
+
+	if http.formvalue("cbi.submit") == "1" and
+	   http.formvalue("token") ~= disp.context.urltoken.stok
+	then
+		http.status(403, "Forbidden")
+		luci.template.render("csrftoken")
+		return
+	end
 
 	local config = self.config or {}
 	local maps = cbi.load(self.model, ...)

modules/luci-base/luasrc/view/cbi/header.htm

@@ -2,6 +2,7 @@
 <form method="post" name="cbi" action="<%=REQUEST_URI%>" enctype="multipart/form-data" onreset="return cbi_validate_reset(this)" onsubmit="return cbi_validate_form(this, '<%:Some fields are invalid, cannot save values!%>')">
 	<div>
 		<script type="text/javascript" src="<%=resource%>/cbi.js"></script>
+		<input type="hidden" name="token" value="<%=token%>" />
 		<input type="hidden" name="cbi.submit" value="1" />
 		<input type="submit" value="<%:Save%>" class="hidden" />
 	</div>