-- Requirements:
-- luacrypto >= 0.3
-- <http://mkottman.github.io/luacrypto/>
+-- luaposix
+-- <https://github.com/luaposix/luaposix>
--
+local sysstat = require("posix.sys.stat")
+local unistd = require("posix.unistd")
+local crypto = require("crypto")
--
--
--
+-- 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 }
}
+-- 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.
local users = {
jason = "secretpassword",
laurent = "s3cr3t",
bob = "ilikelua"
}
-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"
--
--
-- 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 redirect = validate_value("redirect", post["redirect"])
if redirect == nil then
not_found()
redirect_to(redirect)
- -- TODO: Implement time invariant string comparison function to mitigate timing attack.
+ -- Lua hashes strings, so these comparisons are time invariant.
if password == nil or password ~= post["password"] 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
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
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>")
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
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
--
--
-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." .. crypto.hex(crypto.rand.bytes(16))
+ local temporary_file = io.open(temporary_filename, "w")
+ if temporary_file == nil then
+ os.exit(177)
+ end
+ temporary_file:write(crypto.hex(crypto.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 = ""
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
+ salt = component
+ elseif i == 4 then
hmac = component
else
break
return nil
end
- -- TODO: implement time invariant comparison to prevent against timing attack.
- if hmac ~= crypto.hmac.digest("sha1", value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+ -- Lua hashes strings, so these comparisons are time invariant.
+ if hmac ~= crypto.hmac.digest("sha256", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, get_secret()) 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))
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 .. "|" .. crypto.hmac.digest("sha256", authstr, get_secret())
return authstr
end
projects / ps-cgit / blobdiff