ref: master
filters/gentoo-ldap-authentication.lua
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-- 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 |