plugins/mod_saslauth.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8 -- luacheck: ignore 431/log
   9
  10
  11 local st = require "util.stanza";
  12 local sm_bind_resource = require "core.sessionmanager".bind_resource;
  13 local sm_make_authenticated = require "core.sessionmanager".make_authenticated;
  14 local base64 = require "util.encodings".base64;
  15
  16 local usermanager_get_sasl_handler = require "core.usermanager".get_sasl_handler;
  17
  18 local secure_auth_only = module:get_option_boolean("c2s_require_encryption", module:get_option_boolean("require_encryption", false));
  19 local allow_unencrypted_plain_auth = module:get_option_boolean("allow_unencrypted_plain_auth", false)
  20 local insecure_mechanisms = module:get_option_set("insecure_sasl_mechanisms", allow_unencrypted_plain_auth and {} or {"PLAIN", "LOGIN"});
  21 local disabled_mechanisms = module:get_option_set("disable_sasl_mechanisms", { "DIGEST-MD5" });
  22
  23 local log = module._log;
  24
  25 local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';
  26 local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';
  27
  28 local function build_reply(status, ret, err_msg)
  29         local reply = st.stanza(status, {xmlns = xmlns_sasl});
  30         if status == "failure" then
  31                 reply:tag(ret):up();
  32                 if err_msg then reply:tag("text"):text(err_msg); end
  33         elseif status == "challenge" or status == "success" then
  34                 if ret == "" then
  35                         reply:text("=")
  36                 elseif ret then
  37                         reply:text(base64.encode(ret));
  38                 end
  39         else
  40                 module:log("error", "Unknown sasl status: %s", status);
  41         end
  42         return reply;
  43 end
  44
  45 local function handle_status(session, status, ret, err_msg)
  46         if status == "failure" then
  47                 module:fire_event("authentication-failure", { session = session, condition = ret, text = err_msg });
  48                 session.sasl_handler = session.sasl_handler:clean_clone();
  49         elseif status == "success" then
  50                 local ok, err = sm_make_authenticated(session, session.sasl_handler.username);
  51                 if ok then
  52                         module:fire_event("authentication-success", { session = session });
  53                         session.sasl_handler = nil;
  54                         session:reset_stream();
  55                 else
  56                         module:log("warn", "SASL succeeded but username was invalid");
  57                         module:fire_event("authentication-failure", { session = session, condition = "not-authorized", text = err });
  58                         session.sasl_handler = session.sasl_handler:clean_clone();
  59                         return "failure", "not-authorized", "User authenticated successfully, but username was invalid";
  60                 end
  61         end
  62         return status, ret, err_msg;
  63 end
  64
  65 local function sasl_process_cdata(session, stanza)
  66         local text = stanza[1];
  67         if text then
  68                 text = base64.decode(text);
  69                 --log("debug", "AUTH: %s", text:gsub("[%z\001-\008\011\012\014-\031]", " "));
  70                 if not text then
  71                         session.sasl_handler = nil;
  72                         session.send(build_reply("failure", "incorrect-encoding"));
  73                         return true;
  74                 end
  75         end
  76         local status, ret, err_msg = session.sasl_handler:process(text);
  77         status, ret, err_msg = handle_status(session, status, ret, err_msg);
  78         local s = build_reply(status, ret, err_msg);
  79         log("debug", "sasl reply: %s", s);
  80         session.send(s);
  81         return true;
  82 end
  83
  84 module:hook_tag(xmlns_sasl, "success", function (session)
  85         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
  86         module:log("debug", "SASL EXTERNAL with %s succeeded", session.to_host);
  87         session.external_auth = "succeeded"
  88         session:reset_stream();
  89         session:open_stream(session.from_host, session.to_host);
  90
  91         module:fire_event("s2s-authenticated", { session = session, host = session.to_host });
  92         return true;
  93 end)
  94
  95 module:hook_tag(xmlns_sasl, "failure", function (session, stanza)
  96         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
  97
  98         local text = stanza:get_child_text("text");
  99         local condition = "unknown-condition";
 100         for child in stanza:childtags() do
 101                 if child.name ~= "text" then
 102                         condition = child.name;
 103                         break;
 104                 end
 105         end
 106         if text and condition then
 107                 condition = condition .. ": " .. text;
 108         end
 109         module:log("info", "SASL EXTERNAL with %s failed: %s", session.to_host, condition);
 110
 111         session.external_auth = "failed"
 112         session.external_auth_failure_reason = condition;
 113 end, 500)
 114
 115 module:hook_tag(xmlns_sasl, "failure", function (session, stanza) -- luacheck: ignore 212/stanza
 116         session.log("debug", "No fallback from SASL EXTERNAL failure, giving up");
 117         session:close(nil, session.external_auth_failure_reason);
 118         return true;
 119 end, 90)
 120
 121 module:hook_tag("http://etherx.jabber.org/streams", "features", function (session, stanza)
 122         if session.type ~= "s2sout_unauthed" or not session.secure then return; end
 123
 124         local mechanisms = stanza:get_child("mechanisms", xmlns_sasl)
 125         if mechanisms then
 126                 for mech in mechanisms:childtags() do
 127                         if mech[1] == "EXTERNAL" then
 128                                 module:log("debug", "Initiating SASL EXTERNAL with %s", session.to_host);
 129                                 local reply = st.stanza("auth", {xmlns = xmlns_sasl, mechanism = "EXTERNAL"});
 130                                 reply:text(base64.encode(session.from_host))
 131                                 session.sends2s(reply)
 132                                 session.external_auth = "attempting"
 133                                 return true
 134                         end
 135                 end
 136         end
 137 end, 150);
 138
 139 local function s2s_external_auth(session, stanza)
 140         if session.external_auth ~= "offered" then return end -- Unexpected request
 141
 142         local mechanism = stanza.attr.mechanism;
 143
 144         if mechanism ~= "EXTERNAL" then
 145                 session.sends2s(build_reply("failure", "invalid-mechanism"));
 146                 return true;
 147         end
 148
 149         if not session.secure then
 150                 session.sends2s(build_reply("failure", "encryption-required"));
 151                 return true;
 152         end
 153
 154         local text = stanza[1];
 155         if not text then
 156                 session.sends2s(build_reply("failure", "malformed-request"));
 157                 return true;
 158         end
 159
 160         text = base64.decode(text);
 161         if not text then
 162                 session.sends2s(build_reply("failure", "incorrect-encoding"));
 163                 return true;
 164         end
 165
 166         -- The text value is either "" or equals session.from_host
 167         if not ( text == "" or text == session.from_host ) then
 168                 session.sends2s(build_reply("failure", "invalid-authzid"));
 169                 return true;
 170         end
 171
 172         -- We've already verified the external cert identity before offering EXTERNAL
 173         if session.cert_chain_status ~= "valid" or session.cert_identity_status ~= "valid" then
 174                 session.sends2s(build_reply("failure", "not-authorized"));
 175                 session:close();
 176                 return true;
 177         end
 178
 179         -- Success!
 180         session.external_auth = "succeeded";
 181         session.sends2s(build_reply("success"));
 182         module:log("info", "Accepting SASL EXTERNAL identity from %s", session.from_host);
 183         module:fire_event("s2s-authenticated", { session = session, host = session.from_host });
 184         session:reset_stream();
 185         return true;
 186 end
 187
 188 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:auth", function(event)
 189         local session, stanza = event.origin, event.stanza;
 190         if session.type == "s2sin_unauthed" then
 191                 return s2s_external_auth(session, stanza)
 192         end
 193
 194         if session.type ~= "c2s_unauthed" or module:get_host_type() ~= "local" then return; end
 195
 196         if session.sasl_handler and session.sasl_handler.selected then
 197                 session.sasl_handler = nil; -- allow starting a new SASL negotiation before completing an old one
 198         end
 199         if not session.sasl_handler then
 200                 session.sasl_handler = usermanager_get_sasl_handler(module.host, session);
 201         end
 202         local mechanism = stanza.attr.mechanism;
 203         if not session.secure and (secure_auth_only or insecure_mechanisms:contains(mechanism)) then
 204                 session.send(build_reply("failure", "encryption-required"));
 205                 return true;
 206         elseif disabled_mechanisms:contains(mechanism) then
 207                 session.send(build_reply("failure", "invalid-mechanism"));
 208                 return true;
 209         end
 210         local valid_mechanism = session.sasl_handler:select(mechanism);
 211         if not valid_mechanism then
 212                 session.send(build_reply("failure", "invalid-mechanism"));
 213                 return true;
 214         end
 215         return sasl_process_cdata(session, stanza);
 216 end);
 217 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:response", function(event)
 218         local session = event.origin;
 219         if not(session.sasl_handler and session.sasl_handler.selected) then
 220                 session.send(build_reply("failure", "not-authorized", "Out of order SASL element"));
 221                 return true;
 222         end
 223         return sasl_process_cdata(session, event.stanza);
 224 end);
 225 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:abort", function(event)
 226         local session = event.origin;
 227         session.sasl_handler = nil;
 228         session.send(build_reply("failure", "aborted"));
 229         return true;
 230 end);
 231
 232 local function tls_unique(self)
 233         return self.userdata["tls-unique"]:getpeerfinished();
 234 end
 235
 236 local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };
 237 local bind_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-bind' };
 238 local xmpp_session_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-session' };
 239 module:hook("stream-features", function(event)
 240         local origin, features = event.origin, event.features;
 241         local log = origin.log or log;
 242         if not origin.username then
 243                 if secure_auth_only and not origin.secure then
 244                         log("debug", "Not offering authentication on insecure connection");
 245                         return;
 246                 end
 247                 local sasl_handler = usermanager_get_sasl_handler(module.host, origin)
 248                 origin.sasl_handler = sasl_handler;
 249                 if origin.encrypted then
 250                         -- check whether LuaSec has the nifty binding to the function needed for tls-unique
 251                         -- FIXME: would be nice to have this check only once and not for every socket
 252                         if sasl_handler.add_cb_handler then
 253                                 local socket = origin.conn:socket();
 254                                 if socket.getpeerfinished then
 255                                         sasl_handler:add_cb_handler("tls-unique", tls_unique);
 256                                 end
 257                                 sasl_handler["userdata"] = {
 258                                         ["tls-unique"] = socket;
 259                                 };
 260                         end
 261                 end
 262                 local mechanisms = st.stanza("mechanisms", mechanisms_attr);
 263                 local sasl_mechanisms = sasl_handler:mechanisms()
 264                 for mechanism in pairs(sasl_mechanisms) do
 265                         if disabled_mechanisms:contains(mechanism) then
 266                                 log("debug", "Not offering disabled mechanism %s", mechanism);
 267                         elseif not origin.secure and insecure_mechanisms:contains(mechanism) then
 268                                 log("debug", "Not offering mechanism %s on insecure connection", mechanism);
 269                         else
 270                                 log("debug", "Offering mechanism %s", mechanism);
 271                                 mechanisms:tag("mechanism"):text(mechanism):up();
 272                         end
 273                 end
 274                 if mechanisms[1] then
 275                         features:add_child(mechanisms);
 276                 elseif not next(sasl_mechanisms) then
 277                         local authmod = module:get_option_string("authentication", "internal_plain");
 278                         log("error", "No available SASL mechanisms, verify that the configured authentication module '%s' is loaded and configured correctly", authmod);
 279                 else
 280                         log("warn", "All available authentication mechanisms are either disabled or not suitable for an insecure connection");
 281                 end
 282         else
 283                 features:tag("bind", bind_attr):tag("required"):up():up();
 284                 features:tag("session", xmpp_session_attr):tag("optional"):up():up();
 285         end
 286 end);
 287
 288 module:hook("s2s-stream-features", function(event)
 289         local origin, features = event.origin, event.features;
 290         if origin.secure and origin.type == "s2sin_unauthed" then
 291                 -- Offer EXTERNAL only if both chain and identity is valid.
 292                 if origin.cert_chain_status == "valid" and origin.cert_identity_status == "valid" then
 293                         module:log("debug", "Offering SASL EXTERNAL");
 294                         origin.external_auth = "offered"
 295                         features:tag("mechanisms", { xmlns = xmlns_sasl })
 296                                 :tag("mechanism"):text("EXTERNAL")
 297                         :up():up();
 298                 end
 299         end
 300 end);
 301
 302 module:hook("stanza/iq/urn:ietf:params:xml:ns:xmpp-bind:bind", function(event)
 303         local origin, stanza = event.origin, event.stanza;
 304         local resource;
 305         if stanza.attr.type == "set" then
 306                 local bind = stanza.tags[1];
 307                 resource = bind:get_child("resource");
 308                 resource = resource and #resource.tags == 0 and resource[1] or nil;
 309         end
 310         local success, err_type, err, err_msg = sm_bind_resource(origin, resource);
 311         if success then
 312                 origin.send(st.reply(stanza)
 313                         :tag("bind", { xmlns = xmlns_bind })
 314                         :tag("jid"):text(origin.full_jid));
 315                 origin.log("debug", "Resource bound: %s", origin.full_jid);
 316         else
 317                 origin.send(st.error_reply(stanza, err_type, err, err_msg));
 318                 origin.log("debug", "Resource bind failed: %s", err_msg or err);
 319         end
 320         return true;
 321 end);
 322
 323 local function handle_legacy_session(event)
 324         event.origin.send(st.reply(event.stanza));
 325         return true;
 326 end
 327
 328 module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);
 329 module:hook("iq/host/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);