-- This script may be used with the auth-filter. Be sure to configure it as you wish.
--
-- Requirements:
-- luaossl
-- <http://25thandclement.com/~william/projects/luaossl.html>
-- lualdap >= 1.2
-- <https://git.zx2c4.com/lualdap/about/>
-- luaposix
-- <https://github.com/luaposix/luaposix>
--
local sysstat = require("posix.sys.stat")
local unistd = require("posix.unistd")
local lualdap = require("lualdap")
local rand = require("openssl.rand")
local hmac = require("openssl.hmac")
--
--
-- Configure these variables for your settings.
--
--
-- A list of password protected repositories, with which gentooAccess
-- group is allowed to access each one.
local protected_repos = {
glouglou = "infra",
portage = "dev"
}
-- 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"
--
--
-- Authentication functions follow below. Swap these out if you want different authentication semantics.
--
--
-- Sets HTTP cookie headers based on post and sets up redirection.
function authenticate_post()
local redirect = validate_value("redirect", post["redirect"])
if redirect == nil then
not_found()
return 0
end
redirect_to(redirect)
local groups = gentoo_ldap_user_groups(post["username"], post["password"])
if groups == nil then
set_cookie("cgitauth", "")
else
-- One week expiration time
set_cookie("cgitauth", secure_value("gentoogroups", table.concat(groups, ","), os.time() + 604800))
end
html("\n")
return 0
end
-- Returns 1 if the cookie is valid and 0 if it is not.
function authenticate_cookie()
local required_group = protected_repos[cgit["repo"]]
if required_group == nil then
-- We return as valid if the repo is not protected.
return 1
end
local user_groups = validate_value("gentoogroups", get_cookie(http["cookie"], "cgitauth"))
if user_groups == nil or user_groups == "" then
return 0
end
for group in string.gmatch(user_groups, "[^,]+") do
if group == required_group then
return 1
end
end
return 0
end
-- Prints the html for the login form.
function body()
html("<h2>Gentoo LDAP Authentication Required</h2>")
html("<form method='post' action='")
html_attr(cgit["login"])
html("'>")
html("<input type='hidden' name='redirect' value='")
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>")
html("<tr><td><label for='password'>Password:</label></td><td><input id='password' name='password' type='password' /></td></tr>")
html("<tr><td colspan='2'><input value='Login' type='submit' /></td></tr>")
html("</table></form>")
return 0
end
--
--
-- Gentoo LDAP support.
--
--
function gentoo_ldap_user_groups(username, password)
-- Ensure the user is alphanumeric
if username == nil or username:match("%W") then
return nil
end
local who = "uid=" .. username .. ",ou=devs,dc=gentoo,dc=org"
local ldap, err = lualdap.open_simple {
uri = "ldap://ldap1.gentoo.org",
who = who,
password = password,
starttls = true,
certfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.crt",
keyfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.key",
cacertfile = "/var/www/uwsgi/cgit/gentoo-ldap/ca.pem"
}
if ldap == nil then
return nil
end
local group_suffix = ".group"
local group_suffix_len = group_suffix:len()
local groups = {}
for dn, attribs in ldap:search { base = who, scope = "subtree" } do
local access = attribs["gentooAccess"]
if dn == who and access ~= nil then
for i, v in ipairs(access) do
local vlen = v:len()
if vlen > group_suffix_len and v:sub(-group_suffix_len) == group_suffix then
table.insert(groups, v:sub(1, vlen - group_suffix_len))
end
end
end
end
ldap:close()
return groups
end
--
--
-- Wrapper around filter API, exposing the http table, the cgit table, and the post table to the above functions.
--
--
local actions = {}
actions["authenticate-post"] = authenticate_post
actions["authenticate-cookie"] = authenticate_cookie
actions["body"] = body
function filter_open(...)
action = actions[select(1, ...)]
http = {}
http["cookie"] = select(2, ...)
http["method"] = select(3, ...)
http["query"] = select(4, ...)
http["referer"] = select(5, ...)
http["path"] = select(6, ...)
http["host"] = select(7, ...)
http["https"] = select(8, ...)
cgit = {}
cgit["repo"] = select(9, ...)
cgit["page"] = select(10, ...)
cgit["url"] = select(11, ...)
cgit["login"] = select(12, ...)
end
function filter_close()
return action()
end
function filter_write(str)
post = parse_qs(str)
end
--
--
-- Utility functions based on keplerproject/wsapi.
--
--
function url_decode(str)
if not str then
return ""
end
str = string.gsub(str, "+", " ")
str = string.gsub(str, "%%(%x%x)", function(h) return string.char(tonumber(h, 16)) end)
str = string.gsub(str, "\r\n", "\n")
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
tab[url_decode(key)] = url_decode(val)
end
return tab
end
function get_cookie(cookies, name)
cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";")
return 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
