1-- This script may be used with the auth-filter. Be sure to configure it as you wish.
  2--
  3-- Requirements:
  4-- 	luacrypto >= 0.3
  5-- 	<http://mkottman.github.io/luacrypto/>
  6-- 	lualdap >= 1.2
  7-- 	<http://git.zx2c4.com/lualdap/about/>
  8--
  9
 10
 11--
 12--
 13-- Configure these variables for your settings.
 14--
 15--
 16
 17-- A list of password protected repositories, with which gentooAccess
 18-- group is allowed to access each one.
 19local protected_repos = {
 20	glouglou = "infra",
 21	portage = "dev"
 22}
 23
 24
 25-- All cookies will be authenticated based on this secret. Make it something
 26-- totally random and impossible to guess. It should be large.
 27local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
 28
 29
 30
 31--
 32--
 33-- Authentication functions follow below. Swap these out if you want different authentication semantics.
 34--
 35--
 36
 37-- Sets HTTP cookie headers based on post and sets up redirection.
 38function authenticate_post()
 39	local redirect = validate_value("redirect", post["redirect"])
 40
 41	if redirect == nil then
 42		not_found()
 43		return 0
 44	end
 45
 46	redirect_to(redirect)
 47	
 48	local groups = gentoo_ldap_user_groups(post["username"], post["password"])
 49	if groups == nil then
 50		set_cookie("cgitauth", "")
 51	else
 52		-- One week expiration time
 53		set_cookie("cgitauth", secure_value("gentoogroups", table.concat(groups, ","), os.time() + 604800))
 54	end
 55
 56	html("\n")
 57	return 0
 58end
 59
 60
 61-- Returns 1 if the cookie is valid and 0 if it is not.
 62function authenticate_cookie()
 63	local required_group = protected_repos[cgit["repo"]]
 64	if required_group == nil then
 65		-- We return as valid if the repo is not protected.
 66		return 1
 67	end
 68	
 69	local user_groups = validate_value("gentoogroups", get_cookie(http["cookie"], "cgitauth"))
 70	if user_groups == nil or user_groups == "" then
 71		return 0
 72	end
 73	for group in string.gmatch(user_groups, "[^,]+") do
 74		if group == required_group then
 75			return 1
 76		end
 77	end
 78	return 0
 79end
 80
 81-- Prints the html for the login form.
 82function body()
 83	html("<h2>Gentoo LDAP Authentication Required</h2>")
 84	html("<form method='post' action='")
 85	html_attr(cgit["login"])
 86	html("'>")
 87	html("<input type='hidden' name='redirect' value='")
 88	html_attr(secure_value("redirect", cgit["url"], 0))
 89	html("' />")
 90	html("<table>")
 91	html("<tr><td><label for='username'>Username:</label></td><td><input id='username' name='username' autofocus /></td></tr>")
 92	html("<tr><td><label for='password'>Password:</label></td><td><input id='password' name='password' type='password' /></td></tr>")
 93	html("<tr><td colspan='2'><input value='Login' type='submit' /></td></tr>")
 94	html("</table></form>")
 95
 96	return 0
 97end
 98
 99--
100--
101-- Gentoo LDAP support.
102--
103--
104
105local lualdap = require("lualdap")
106
107function gentoo_ldap_user_groups(username, password)
108	-- Ensure the user is alphanumeric
109	if username:match("%W") then
110		return nil
111	end
112
113	local who = "uid=" .. username .. ",ou=devs,dc=gentoo,dc=org"
114
115	local ldap, err = lualdap.open_simple {
116		uri = "ldap://ldap1.gentoo.org",
117		who = who,
118		password = password,
119		starttls = true,
120		certfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.crt",
121		keyfile = "/var/www/uwsgi/cgit/gentoo-ldap/star.gentoo.org.key",
122		cacertfile = "/var/www/uwsgi/cgit/gentoo-ldap/ca.pem"
123	}
124	if ldap == nil then
125		return nil
126	end
127
128	local group_suffix = ".group"
129	local group_suffix_len = group_suffix:len()
130	local groups = {}
131	for dn, attribs in ldap:search { base = who, scope = "subtree" } do
132		local access = attribs["gentooAccess"]
133		if dn == who and access ~= nil then
134			for i, v in ipairs(access) do
135				local vlen = v:len()
136				if vlen > group_suffix_len and v:sub(-group_suffix_len) == group_suffix then
137					table.insert(groups, v:sub(1, vlen - group_suffix_len))
138				end
139			end
140		end
141	end
142
143	ldap:close()
144
145	return groups
146end
147
148--
149--
150-- Wrapper around filter API, exposing the http table, the cgit table, and the post table to the above functions.
151--
152--
153
154local actions = {}
155actions["authenticate-post"] = authenticate_post
156actions["authenticate-cookie"] = authenticate_cookie
157actions["body"] = body
158
159function filter_open(...)
160	action = actions[select(1, ...)]
161
162	http = {}
163	http["cookie"] = select(2, ...)
164	http["method"] = select(3, ...)
165	http["query"] = select(4, ...)
166	http["referer"] = select(5, ...)
167	http["path"] = select(6, ...)
168	http["host"] = select(7, ...)
169	http["https"] = select(8, ...)
170
171	cgit = {}
172	cgit["repo"] = select(9, ...)
173	cgit["page"] = select(10, ...)
174	cgit["url"] = select(11, ...)
175	cgit["login"] = select(12, ...)
176
177end
178
179function filter_close()
180	return action()
181end
182
183function filter_write(str)
184	post = parse_qs(str)
185end
186
187
188--
189--
190-- Utility functions based on keplerproject/wsapi.
191--
192--
193
194function url_decode(str)
195	if not str then
196		return ""
197	end
198	str = string.gsub(str, "+", " ")
199	str = string.gsub(str, "%%(%x%x)", function(h) return string.char(tonumber(h, 16)) end)
200	str = string.gsub(str, "\r\n", "\n")
201	return str
202end
203
204function url_encode(str)
205	if not str then
206		return ""
207	end
208	str = string.gsub(str, "\n", "\r\n")
209	str = string.gsub(str, "([^%w ])", function(c) return string.format("%%%02X", string.byte(c)) end)
210	str = string.gsub(str, " ", "+")
211	return str
212end
213
214function parse_qs(qs)
215	local tab = {}
216	for key, val in string.gmatch(qs, "([^&=]+)=([^&=]*)&?") do
217		tab[url_decode(key)] = url_decode(val)
218	end
219	return tab
220end
221
222function get_cookie(cookies, name)
223	cookies = string.gsub(";" .. cookies .. ";", "%s*;%s*", ";")
224	return string.match(cookies, ";" .. name .. "=(.-);")
225end
226
227
228--
229--
230-- Cookie construction and validation helpers.
231--
232--
233
234local crypto = require("crypto")
235
236-- Returns value of cookie if cookie is valid. Otherwise returns nil.
237function validate_value(expected_field, cookie)
238	local i = 0
239	local value = ""
240	local field = ""
241	local expiration = 0
242	local salt = ""
243	local hmac = ""
244
245	if cookie == nil or cookie:len() < 3 or cookie:sub(1, 1) == "|" then
246		return nil
247	end
248
249	for component in string.gmatch(cookie, "[^|]+") do
250		if i == 0 then
251			field = component
252		elseif i == 1 then
253			value = component
254		elseif i == 2 then
255			expiration = tonumber(component)
256			if expiration == nil then
257				expiration = -1
258			end
259		elseif i == 3 then
260			salt = component
261		elseif i == 4 then
262			hmac = component
263		else
264			break
265		end
266		i = i + 1
267	end
268
269	if hmac == nil or hmac:len() == 0 then
270		return nil
271	end
272
273	-- Lua hashes strings, so these comparisons are time invariant.
274	if hmac ~= crypto.hmac.digest("sha1", field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
275		return nil
276	end
277
278	if expiration == -1 or (expiration ~= 0 and expiration <= os.time()) then
279		return nil
280	end
281
282	if url_decode(field) ~= expected_field then
283		return nil
284	end
285
286	return url_decode(value)
287end
288
289function secure_value(field, value, expiration)
290	if value == nil or value:len() <= 0 then
291		return ""
292	end
293
294	local authstr = ""
295	local salt = crypto.hex(crypto.rand.bytes(16))
296	value = url_encode(value)
297	field = url_encode(field)
298	authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt
299	authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
300	return authstr
301end
302
303function set_cookie(cookie, value)
304	html("Set-Cookie: " .. cookie .. "=" .. value .. "; HttpOnly")
305	if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then
306		html("; secure")
307	end
308	html("\n")
309end
310
311function redirect_to(url)
312	html("Status: 302 Redirect\n")
313	html("Cache-Control: no-cache, no-store\n")
314	html("Location: " .. url .. "\n")
315end
316
317function not_found()
318	html("Status: 404 Not Found\n")
319	html("Cache-Control: no-cache, no-store\n\n")
320end