]> gitweb.ps.run Git - ps-cgit/blobdiff - filters/simple-authentication.lua
auth: add basic authentication filter framework
[ps-cgit] / filters / simple-authentication.lua
diff --git a/filters/simple-authentication.lua b/filters/simple-authentication.lua
new file mode 100644 (file)
index 0000000..4cd4983
--- /dev/null
@@ -0,0 +1,225 @@
+-- This script may be used with the auth-filter. Be sure to configure it as you wish.
+--
+-- Requirements:
+--     luacrypto >= 0.3
+--     <http://mkottman.github.io/luacrypto/>
+--
+
+
+--
+--
+-- Configure these variables for your settings.
+--
+--
+
+local protected_repos = {
+       glouglou        = { laurent = true, jason = true },
+       qt              = { jason = true, bob = true }
+}
+
+local users = {
+       jason           = "secretpassword",
+       laurent         = "s3cr3t",
+       bob             = "ilikelua"
+}
+
+local secret = "BE SURE TO CUSTOMIZE THIS STRING TO SOMETHING BIG AND RANDOM"
+
+
+
+--
+--
+-- Authentication functions follow below. Swap these out if you want different authentication semantics.
+--
+--
+
+-- Sets HTTP cookie headers based on post
+function authenticate_post()
+       local password = users[post["username"]]
+       -- TODO: Implement time invariant string comparison function to mitigate against timing attack.
+       if password == nil or password ~= post["password"] then
+               construct_cookie("", "cgitauth")
+       else
+               construct_cookie(post["username"], "cgitauth")
+       end
+       return 0
+end
+
+
+-- Returns 1 if the cookie is valid and 0 if it is not.
+function authenticate_cookie()
+       accepted_users = protected_repos[cgit["repo"]]
+       if accepted_users == nil then
+               -- We return as valid if the repo is not protected.
+               return 1
+       end
+
+       local username = validate_cookie(get_cookie(http["cookie"], "cgitauth"))
+       if username == nil or not accepted_users[username] 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("<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
+
+
+--
+--
+-- Cookie construction and validation helpers.
+--
+--
+
+local crypto = require("crypto")
+
+-- Returns username of cookie if cookie is valid. Otherwise returns nil.
+function validate_cookie(cookie)
+       local i = 0
+       local username = ""
+       local expiration = 0
+       local salt = ""
+       local hmac = ""
+
+       if cookie:len() < 3 or cookie:sub(1, 1) == "|" then
+               return nil
+       end
+
+       for component in string.gmatch(cookie, "[^|]+") do
+               if i == 0 then
+                       username = component
+               elseif i == 1 then
+                       expiration = tonumber(component)
+                       if expiration == nil then
+                               expiration = 0
+                       end
+               elseif i == 2 then
+                       salt = component
+               elseif i == 3 then
+                       hmac = component
+               else
+                       break
+               end
+               i = i + 1
+       end
+
+       if hmac == nil or hmac:len() == 0 then
+               return nil
+       end
+
+       -- TODO: implement time invariant comparison to prevent against timing attack.
+       if hmac ~= crypto.hmac.digest("sha1", username .. "|" .. tostring(expiration) .. "|" .. salt, secret) then
+               return nil
+       end
+
+       if expiration <= os.time() then
+               return nil
+       end
+
+       return username:lower()
+end
+
+function construct_cookie(username, cookie)
+       local authstr = ""
+       if username:len() > 0 then
+               -- One week expiration time
+               local expiration = os.time() + 604800
+               local salt = crypto.hex(crypto.rand.bytes(16))
+
+               authstr = username .. "|" .. tostring(expiration) .. "|" .. salt
+               authstr = authstr .. "|" .. crypto.hmac.digest("sha1", authstr, secret)
+       end
+
+       html("Set-Cookie: " .. cookie .. "=" .. authstr .. "; HttpOnly")
+       if http["https"] == "yes" or http["https"] == "on" or http["https"] == "1" then
+               html("; secure")
+       end
+       html("\n")
+end
+
+--
+--
+-- Wrapper around filter API follows below, 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"] = ""
+       for _ in cgit["url"]:gfind("/") do
+               cgit["login"] = cgit["login"] .. "../"
+       end
+       cgit["login"] = cgit["login"] .. "?p=login"
+
+end
+
+function filter_close()
+       return action()
+end
+
+function filter_write(str)
+       post = parse_qs(str)
+end
+
+
+--
+--
+-- Utility functions follow below, 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 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