-- This script may be used with the auth-filter.
--
-- Requirements:
-- 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")
-- This file should contain a series of lines in the form of:
-- username1:hash1
-- username2:hash2
-- username3:hash3
-- ...
-- Hashes can be generated using something like `mkpasswd -m sha-512 -R 300000`.
-- This file should not be world-readable.
local users_filename = "/etc/cgit-auth/users"
-- This file should contain a series of lines in the form of:
-- groupname1:username1,username2,username3,...
-- ...
local groups_filename = "/etc/cgit-auth/groups"
-- This file should contain a series of lines in the form of:
-- reponame1:groupname1,groupname2,groupname3,...
-- ...
local repos_filename = "/etc/cgit-auth/repos"
-- Set this to a path this script can write to for storing a persistent
-- cookie secret, which should not be world-readable.
local secret_filename = "/var/cache/cgit/auth-secret"
--
--
-- Authentication functions follow below. Swap these out if you want different authentication semantics.
--
--
-- Looks up a hash for a given user.
function lookup_hash(user)
local line
for line in io.lines(users_filename) do
local u, h = string.match(line, "(.-):(.+)")
if u:lower() == user:lower() then
return h
end
end
return nil
end
-- Looks up users for a given repo.
function lookup_users(repo)
local users = nil
local groups = nil
local line, group, user
for line in io.lines(repos_filename) do
local r, g = string.match(line, "(.-):(.+)")
if r == repo then
groups = { }
for group in string.gmatch(g, "([^,]+)") do
groups[group:lower()] = true
end
break
end
end
if groups == nil then
return nil
end
for line in io.lines(groups_filename) do
local g, u = string.match(line, "(.-):(.+)")
if groups[g:lower()] then
if users == nil then
users = { }
end
for user in string.gmatch(u, "([^,]+)") do
users[user:lower()] = true
end
end
end
return users
end
-- Sets HTTP cookie headers based on post and sets up redirection.
function authenticate_post()
local hash = lookup_hash(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
-- One week expiration time
local username = secure_value("username", post["username"], os.time() + 604800)
set_cookie("cgitauth", username)
end
html("\n")
return 0
end
-- Returns 1 if the cookie is valid and 0 if it is not.
function authenticate_cookie()
accepted_users = lookup_users(cgit["repo"])
if accepted_users == nil then
-- We return as valid if the repo is not protected.
return 1
end
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
end
end
-- Prints the html for the login form.
function body()
html("<h2>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
--
--
-- 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 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
