diff options
| -rw-r--r-- | filters/file-authentication.lua | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/filters/file-authentication.lua b/filters/file-authentication.lua new file mode 100644 index 0000000..6ee1e19 --- /dev/null +++ b/filters/file-authentication.lua @@ -0,0 +1,352 @@ +-- This script may be used with the auth-filter. +-- +-- 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") + + +-- 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 + + +-- +-- +-- 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." .. 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(expected_field, cookie) + local i = 0 + local value = "" + local field = "" + local expiration = 0 + local salt = "" + local hmac = "" + + 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 + hmac = component + else + break + end + i = i + 1 + end + + if hmac == nil or hmac:len() == 0 then + return nil + end + + -- 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 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 = crypto.hex(crypto.rand.bytes(16)) + value = url_encode(value) + field = url_encode(field) + authstr = field .. "|" .. value .. "|" .. tostring(expiration) .. "|" .. salt + authstr = authstr .. "|" .. crypto.hmac.digest("sha256", authstr, get_secret()) + 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 |