luci-base: dispatcher.lua: pass permission state to legacy CBI templates

Ref: https://github.com/openwrt/luci/issues/3937
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

modules/luci-base/luasrc/dispatcher.lua

@@ -1329,12 +1329,23 @@ function _cbi(self, ...)
 	local cbi = require "luci.cbi"
 	local tpl = require "luci.template"
 	local http = require "luci.http"
+	local util = require "luci.util"
 
 	local config = self.config or {}
 	local maps = cbi.load(self.model, ...)
 
 	local state = nil
 
+	local function has_uci_access(config, level)
+		local rv = util.ubus("session", "access", {
+			ubus_rpc_session = context.authsession,
+			scope = "uci", object = config,
+			["function"] = level
+		})
+
+		return (type(rv) == "table" and rv.access == true) or false
+	end
+
 	local i, res
 	for i, res in ipairs(maps) do
 		if util.instanceof(res, cbi.SimpleForm) then
@@ -1388,6 +1399,7 @@ function _cbi(self, ...)
 	local applymap   = false
 	local pageaction = true
 	local parsechain = { }
+	local writable   = false
 
 	for i, res in ipairs(maps) do
 		if res.apply_needed and res.parsechain then
@@ -1413,12 +1425,19 @@ function _cbi(self, ...)
 	end
 
 	for i, res in ipairs(maps) do
+		local is_readable_map = has_uci_access(res.config, "read")
+		local is_writable_map = has_uci_access(res.config, "write")
+
+		writable = writable or is_writable_map
+
 		res:render({
 			firstmap   = (i == 1),
 			redirect   = redirect,
 			messages   = messages,
 			pageaction = pageaction,
-			parsechain = parsechain
+			parsechain = parsechain,
+			readable   = is_readable_map,
+			writable   = is_writable_map
 		})
 	end
 
@@ -1429,7 +1448,8 @@ function _cbi(self, ...)
 			redirect      = redirect,
 			state         = state,
 			autoapply     = config.autoapply,
-			trigger_apply = applymap
+			trigger_apply = applymap,
+			writable      = writable
 		})
 	end
 end