X-Git-Url: https://gitweb.ps.run/ps-cgit/blobdiff_plain/9dde6d38e9fc273fc62386eeda0da2e89a2cebfc..cc9b717c875dcd33460b77383b417455b007061e:/filters/simple-authentication.lua

diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
index 230d3a3..23d3457 100644
--- a/filters/simple-authentication.lua
+++ b/filters/simple-authentication.lua
@@ -1,10 +1,15 @@
 -- This script may be used with the auth-filter. Be sure to configure it as you wish.
 --
 -- Requirements:
--- 	luacrypto >= 0.3
--- 	<http://mkottman.github.io/luacrypto/>
+-- 	luaossl
+-- 	<http://25thandclement.com/~william/projects/luaossl.html>
+-- 	luaposix
+-- 	<https://github.com/luaposix/luaposix>
 --
-
+local sysstat = require("posix.sys.stat")
+local unistd = require("posix.unistd")
+local rand = require("openssl.rand")
+local hmac = require("openssl.hmac")
 
 --
 --
@@ -18,24 +23,16 @@ local protected_repos = {
 	qt		= { jason = true, bob = true }
 }
 
--- Please note that, in production, you'll want to replace this simple lookup
--- table with either a table of salted and hashed passwords (using something
--- smart like scrypt), or replace this table lookup with an external support,
--- such as consulting your system's pam / shadow system, or an external
--- database, or an external validating web service. For testing, or for
--- extremely low-security usage, you may be able, however, to get away with
--- compromising on hardcoding the passwords in cleartext, as we have done here.
+-- A list of users and hashes, generated with `mkpasswd -m sha-512 -R 300000`.
 local users = {
-	jason		= "secretpassword",
-	laurent		= "s3cr3t",
-	bob		= "ilikelua"
+	jason		= "$6$rounds=300000$YYJct3n/o.ruYK$HhpSeuCuW1fJkpvMZOZzVizeLsBKcGA/aF2UPuV5v60JyH2MVSG6P511UMTj2F3H75.IT2HIlnvXzNb60FcZH1",
+	laurent		= "$6$rounds=300000$dP0KNHwYb3JKigT$pN/LG7rWxQ4HniFtx5wKyJXBJUKP7R01zTNZ0qSK/aivw8ywGAOdfYiIQFqFhZFtVGvr11/7an.nesvm8iJUi.",
+	bob		= "$6$rounds=300000$jCLCCt6LUpTz$PI1vvd1yaVYcCzqH8QAJFcJ60b6W/6sjcOsU7mAkNo7IE8FRGW1vkjF8I/T5jt/auv5ODLb1L4S2s.CAyZyUC"
 }
 
--- All cookies will be authenticated based on this secret. Make it something
--- totally random and impossible to guess. It should be large.
-local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
-
-
+-- Set this to a path this script can write to for storing a persistent
+-- cookie secret, which should be guarded.
+local secret_filename = "/var/cache/cgit/auth-secret"
 
 --
 --
@@ -45,8 +42,8 @@ local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
 
 -- Sets HTTP cookie headers based on post and sets up redirection.
 function authenticate_post()
-	local password = users[post["username"]]
-	local redirect = validate_value(post["redirect"])
+	local hash = users[post["username"]]
+	local redirect = validate_value("redirect", post["redirect"])
 
 	if redirect == nil then
 		not_found()
@@ -55,12 +52,11 @@ function authenticate_post()
 
 	redirect_to(redirect)
 
-	-- Lua hashes strings, so these comparisons are time invariant.
-	if password == nil or password ~= post["password"] then
+	if hash == nil or hash ~= unistd.crypt(post["password"], hash) then
 		set_cookie("cgitauth", "")
 	else
 		-- One week expiration time
-		local username = secure_value(post["username"], os.time() + 604800)
+		local username = secure_value("username", post["username"], os.time() + 604800)
 		set_cookie("cgitauth", username)
 	end
 
@@ -77,7 +73,7 @@ function authenticate_cookie()
 		return 1
 	end
 
-	local username = validate_value(get_cookie(http["cookie"], "cgitauth"))
+	local username = validate_value("username", get_cookie(http["cookie"], "cgitauth"))
 	if username == nil or not accepted_users[username:lower()] then
 		return 0
 	else
@@ -92,7 +88,7 @@ function body()
 	html_attr(cgit["login"])
 	html("'>")
 	html("<input type='hidden' name='redirect' value='")
-	html_attr(secure_value(cgit["url"], 0))
+	html_attr(secure_value("redirect", cgit["url"], 0))
 	html("' />")
 	html("<table>")
 	html("<tr><td><label for='username'>Username:</label></td><td><input id='username' name='username' autofocus /></td></tr>")
@@ -166,7 +162,7 @@ function url_encode(str)
 		return ""
 	end
 	str = string.gsub(str, "\n", "\r\n")
-	str = string.gsub(str, "([^%w ])", function (c) return string.format("%%%02X", string.byte(c)) end)
+	str = string.gsub(str, "([^%w ])", function(c) return string.format("%%%02X", string.byte(c)) end)
 	str = string.gsub(str, " ", "+")
 	return str
 end
@@ -184,6 +180,13 @@ function get_cookie(cookies, name)
 	return url_decode(string.match(cookies, ";" .. name .. "=(.-);"))
 end
 
+function tohex(b)
+	local x = ""
+	for i = 1, #b do
+		x = x .. string.format("%.2x", string.byte(b, i))
+	end
+	return x
+end
 
 --
 --
@@ -191,15 +194,47 @@ end
 --
 --
 
-local crypto = require("crypto")
+local secret = nil
+
+-- Loads a secret from a file, creates a secret, or returns one from memory.
+function get_secret()
+	if secret ~= nil then
+		return secret
+	end
+	local secret_file = io.open(secret_filename, "r")
+	if secret_file == nil then
+		local old_umask = sysstat.umask(63)
+		local temporary_filename = secret_filename .. ".tmp." .. tohex(rand.bytes(16))
+		local temporary_file = io.open(temporary_filename, "w")
+		if temporary_file == nil then
+			os.exit(177)
+		end
+		temporary_file:write(tohex(rand.bytes(32)))
+		temporary_file:close()
+		unistd.link(temporary_filename, secret_filename) -- Intentionally fails in the case that another process is doing the same.
+		unistd.unlink(temporary_filename)
+		sysstat.umask(old_umask)
+		secret_file = io.open(secret_filename, "r")
+	end
+	if secret_file == nil then
+		os.exit(177)
+	end
+	secret = secret_file:read()
+	secret_file:close()
+	if secret:len() ~= 64 then
+		os.exit(177)
+	end
+	return secret
+end
 
 -- Returns value of cookie if cookie is valid. Otherwise returns nil.
-function validate_value(cookie)
+function validate_value(expected_field, cookie)
 	local i = 0
 	local value = ""
+	local field = ""
 	local expiration = 0
 	local salt = ""
-	local hmac = ""
+	local chmac = ""
 
 	if cookie == nil or cookie:len() < 3 or cookie:sub(1, 1) == "|" then
 		return nil
@@ -207,48 +242,55 @@ function validate_value(cookie)
 
 	for component in string.gmatch(cookie, "[^|]+") do
 		if i == 0 then
-			value = component
+			field = component
 		elseif i == 1 then
+			value = component
+		elseif i == 2 then
 			expiration = tonumber(component)
 			if expiration == nil then
-				expiration = 0
+				expiration = -1
 			end
-		elseif i == 2 then
-			salt = component
 		elseif i == 3 then
-			hmac = component
+			salt = component
+		elseif i == 4 then
+			chmac = component
 		else
 			break
 		end
 		i = i + 1
 	end
 
-	if hmac == nil or hmac:len() == 0 then
+	if chmac == nil or chmac:len() == 0 then
 		return nil
 	end
 
 	-- Lua hashes strings, so these comparisons are time invariant.
-	if hmac ~= crypto.hmac.digest("sha1", value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+	if chmac ~= tohex(hmac.new(get_secret(), "sha256"):final(field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt)) then
+		return nil
+	end
+
+	if expiration == -1 or (expiration ~= 0 and expiration <= os.time()) then
 		return nil
 	end
 
-	if expiration ~= 0 and expiration <= os.time() then
+	if url_decode(field) ~= expected_field then
 		return nil
 	end
 
 	return url_decode(value)
 end
 
-function secure_value(value, expiration)
+function secure_value(field, value, expiration)
 	if value == nil or value:len() <= 0 then
 		return ""
 	end
 
 	local authstr = ""
-	local salt = crypto.hex(crypto.rand.bytes(16))
+	local salt = tohex(rand.bytes(16))
 	value = url_encode(value)
-	authstr = value .. "|" .. tostring(expiration) .. "|" .. salt
-	authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
+	field = url_encode(field)
+	authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
+	authstr = authstr .. "|" .. tohex(hmac.new(get_secret(), "sha256"):final(authstr))
 	return authstr
 end