luci-base: remove security token from urls

Now that sensitive urls require post requests and only accept them if a valid
security token is sent along the request, we can drop the global random url
token to improve LuCI usability.

The main improvement is the ability to use multiple tabs with the same login
session, but also deep linking to specific urls without the need for another
login becomes feasible, e.g. for documentation purposes.

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

modules/luci-base/luasrc/dispatcher.lua

@@ -113,24 +113,11 @@ function authenticator.htmlauth(validator, accs, default)
 		return user
 	end
 
-	if context.urltoken.stok then
-		context.urltoken.stok = nil
-
-		local cookie = 'sysauth=%s; expires=%s; path=%s/' %{
-		    http.getcookie('sysauth') or 'x',
-			'Thu, 01 Jan 1970 01:00:00 GMT',
-			build_url()
-		}
-
-		http.header("Set-Cookie", cookie)
-		http.redirect(build_url())
-	else
 	require("luci.i18n")
 	require("luci.template")
 	context.path = {}
 	http.status(403, "Forbidden")
 	luci.template.render("sysauth", {duser=default, fuser=user})
-	end
 
 	return false
 
@@ -151,19 +138,9 @@ function httpdispatch(request, prefix)
 		end
 	end
 
-	local tokensok = true
 	for node in pathinfo:gmatch("[^/]+") do
-		local tkey, tval
-		if tokensok then
-			tkey, tval = node:match(";(%w+)=([a-fA-F0-9]*)")
-		end
-		if tkey then
-			context.urltoken[tkey] = tval
-		else
-			tokensok = false
 		r[#r+1] = node
 	end
-	end
 
 	local stat, err = util.coxpcall(function()
 		dispatch(context.request)
@@ -311,13 +288,14 @@ function dispatch(request)
 		   resource    = luci.config.main.resourcebase;
 		   ifattr      = function(...) return _ifattr(...) end;
 		   attr        = function(...) return _ifattr(true, ...) end;
-		   token       = ctx.urltoken.stok;
 		   url         = build_url;
 		}, {__index=function(table, key)
 			if key == "controller" then
 				return build_url()
 			elseif key == "REQUEST_URI" then
 				return build_url(unpack(ctx.requestpath))
+			elseif key == "token" then
+				return ctx.authtoken
 			else
 				return rawget(table, key) or _G[key]
 			end
@@ -340,20 +318,17 @@ function dispatch(request)
 		local def  = (type(track.sysauth) == "string") and track.sysauth
 		local accs = def and {track.sysauth} or track.sysauth
 		local sess = ctx.authsession
-		local verifytoken = false
 		if not sess then
 			sess = http.getcookie("sysauth")
 			sess = sess and sess:match("^[a-f0-9]*$")
-			verifytoken = true
 		end
 
 		local sdat = (util.ubus("session", "get", { ubus_rpc_session = sess }) or { }).values
-		local user
+		local user, token
 
 		if sdat then
-			if not verifytoken or ctx.urltoken.stok == sdat.token then
 			user = sdat.user
-			end
+			token = sdat.token
 		else
 			local eu = http.getenv("HTTP_AUTH_USER")
 			local ep = http.getenv("HTTP_AUTH_PASS")
@@ -390,8 +365,8 @@ function dispatch(request)
 						   sess, build_url()
 						})
 
-						ctx.urltoken.stok = token
 						ctx.authsession = sess
+						ctx.authtoken = token
 						ctx.authuser = user
 
 						http.redirect(build_url(unpack(ctx.requestpath)))
@@ -403,6 +378,7 @@ function dispatch(request)
 			end
 		else
 			ctx.authsession = sess
+			ctx.authtoken = token
 			ctx.authuser = user
 		end
 	end
@@ -414,7 +390,7 @@ function dispatch(request)
 			return
 		end
 
-		if http.formvalue("token") ~= ctx.urltoken.stok then
+		if http.formvalue("token") ~= ctx.authtoken then
 			http.status(403, "Forbidden")
 			luci.template.render("csrftoken")
 			return