X-Git-Url: https://gitweb.ps.run/ps-cgit/blobdiff_plain/d6e9200cc35411f3f27426b608bcfdef9348e6d3..034e3c7d56ba71ce281886fe8525b16d4559fac1:/filters/simple-authentication.lua diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua index 4cd4983..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 --- +-- luaossl +-- +-- luaposix +-- -- - +local sysstat = require("posix.sys.stat") +local unistd = require("posix.unistd") +local rand = require("openssl.rand") +local hmac = require("openssl.hmac") -- -- @@ -12,20 +17,22 @@ -- -- +-- A list of password protected repositories along with the users who can access them. local protected_repos = { glouglou = { laurent = true, jason = true }, qt = { jason = true, bob = true } } +-- 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" } -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" -- -- @@ -33,15 +40,27 @@ local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM" -- -- --- Sets HTTP cookie headers based on post +-- Sets HTTP cookie headers based on post and sets up redirection. function authenticate_post() - local password = users[post["username"]] - -- TODO: Implement time invariant string comparison function to mitigate against timing attack. - if password == nil or password ~= post["password"] then - construct_cookie("", "cgitauth") + local hash = users[post["username"]] + local redirect = validate_value("redirect", post["redirect"]) + + if redirect == nil then + not_found() + return 0 + end + + redirect_to(redirect) + + if hash == nil or hash ~= unistd.crypt(post["password"], hash) then + set_cookie("cgitauth", "") else - construct_cookie(post["username"], "cgitauth") + -- One week expiration time + local username = secure_value("username", post["username"], os.time() + 604800) + set_cookie("cgitauth", username) end + + html("\n") return 0 end @@ -54,8 +73,8 @@ function authenticate_cookie() return 1 end - local username = validate_cookie(get_cookie(http["cookie"], "cgitauth")) - if username == nil or not accepted_users[username] then + local username = validate_value("username", get_cookie(http["cookie"], "cgitauth")) + if username == nil or not accepted_users[username:lower()] then return 0 else return 1 @@ -68,6 +87,9 @@ function body() html("
") + html("") html("") html("") html("") @@ -78,81 +100,10 @@ function body() end --- --- --- Cookie construction and validation helpers. --- --- - -local crypto = require("crypto") - --- Returns username of cookie if cookie is valid. Otherwise returns nil. -function validate_cookie(cookie) - local i = 0 - local username = "" - local expiration = 0 - local salt = "" - local hmac = "" - - if cookie:len() < 3 or cookie:sub(1, 1) == "|" then - return nil - end - - for component in string.gmatch(cookie, "[^|]+") do - if i == 0 then - username = component - elseif i == 1 then - expiration = tonumber(component) - if expiration == nil then - expiration = 0 - end - elseif i == 2 then - salt = component - elseif i == 3 then - hmac = component - else - break - end - i = i + 1 - end - - if hmac == nil or hmac:len() == 0 then - return nil - end - - -- TODO: implement time invariant comparison to prevent against timing attack. - if hmac ~= crypto.hmac.digest("sha1", username .. "|" .. tostring(expiration) .. "|" .. salt, secret) then - return nil - end - - if expiration <= os.time() then - return nil - end - - return username:lower() -end - -function construct_cookie(username, cookie) - local authstr = "" - if username:len() > 0 then - -- One week expiration time - local expiration = os.time() + 604800 - local salt = crypto.hex(crypto.rand.bytes(16)) - - authstr = username .. "|" .. tostring(expiration) .. "|" .. salt - authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret) - end - - html("Set-Cookie: " .. cookie .. "=" .. authstr .. "; HttpOnly") - if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then - html("; secure") - end - html("\n") -end -- -- --- Wrapper around filter API follows below, exposing the http table, the cgit table, and the post table to the above functions. +-- Wrapper around filter API, exposing the http table, the cgit table, and the post table to the above functions. -- -- @@ -177,12 +128,7 @@ function filter_open(...) cgit["repo"] = select(9, ...) cgit["page"] = select(10, ...) cgit["url"] = select(11, ...) - - cgit["login"] = "" - for _ in cgit["url"]:gfind("/") do - cgit["login"] = cgit["login"] .. "../" - end - cgit["login"] = cgit["login"] .. "?p=login" + cgit["login"] = select(12, ...) end @@ -197,7 +143,7 @@ end -- -- --- Utility functions follow below, based on keplerproject/wsapi. +-- Utility functions based on keplerproject/wsapi. -- -- @@ -211,6 +157,16 @@ function url_decode(str) return str end +function url_encode(str) + if not str then + 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, " ", "+") + return str +end + function parse_qs(qs) local tab = {} for key, val in string.gmatch(qs, "([^&=]+)=([^&=]*)&?") do @@ -223,3 +179,136 @@ function get_cookie(cookies, name) cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";") 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 + +-- +-- +-- Cookie construction and validation helpers. +-- +-- + +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(expected_field, cookie) + local i = 0 + local value = "" + local field = "" + local expiration = 0 + local salt = "" + local chmac = "" + + if cookie == nil or cookie:len() < 3 or cookie:sub(1, 1) == "|" then + return nil + end + + for component in string.gmatch(cookie, "[^|]+") do + if i == 0 then + field = component + elseif i == 1 then + value = component + elseif i == 2 then + expiration = tonumber(component) + if expiration == nil then + expiration = -1 + end + elseif i == 3 then + salt = component + elseif i == 4 then + chmac = component + else + break + end + i = i + 1 + end + + if chmac == nil or chmac:len() == 0 then + return nil + end + + -- Lua hashes strings, so these comparisons are time invariant. + 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 url_decode(field) ~= expected_field then + return nil + end + + return url_decode(value) +end + +function secure_value(field, value, expiration) + if value == nil or value:len() <= 0 then + return "" + end + + local authstr = "" + local salt = tohex(rand.bytes(16)) + value = url_encode(value) + field = url_encode(field) + authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt + authstr = authstr .. "|" .. tohex(hmac.new(get_secret(), "sha256"):final(authstr)) + return authstr +end + +function set_cookie(cookie, value) + html("Set-Cookie: " .. cookie .. "=" .. value .. "; HttpOnly") + if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then + html("; secure") + end + html("\n") +end + +function redirect_to(url) + html("Status: 302 Redirect\n") + html("Cache-Control: no-cache, no-store\n") + html("Location: " .. url .. "\n") +end + +function not_found() + html("Status: 404 Not Found\n") + html("Cache-Control: no-cache, no-store\n\n") +end