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
   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 s2s_make_authenticated = require "core.s2smanager".make_authenticated;
  15 local base64 = require "util.encodings".base64;
  16
  17 local cert_verify_identity = require "util.certverification".verify_identity;
  18
  19 local nodeprep = require "util.encodings".stringprep.nodeprep;
  20 local usermanager_get_sasl_handler = require "core.usermanager".get_sasl_handler;
  21 local t_concat, t_insert = table.concat, table.insert;
  22 local tostring = tostring;
  23
  24 local secure_auth_only = module:get_option("c2s_require_encryption") or module:get_option("require_encryption");
  25 local anonymous_login = module:get_option("anonymous_login");
  26 local allow_unencrypted_plain_auth = module:get_option("allow_unencrypted_plain_auth")
  27
  28 local log = module._log;
  29
  30 local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';
  31 local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';
  32 local xmlns_stanzas ='urn:ietf:params:xml:ns:xmpp-stanzas';
  33
  34 local new_sasl = require "util.sasl".new;
  35
  36 local anonymous_authentication_profile = {
  37         anonymous = function(username, realm)
  38                 return true; -- for normal usage you should always return true here
  39         end
  40 };
  41
  42 local function build_reply(status, ret, err_msg)
  43         local reply = st.stanza(status, {xmlns = xmlns_sasl});
  44         if status == "challenge" then
  45                 --log("debug", "CHALLENGE: %s", ret or "");
  46                 reply:text(base64.encode(ret or ""));
  47         elseif status == "failure" then
  48                 reply:tag(ret):up();
  49                 if err_msg then reply:tag("text"):text(err_msg); end
  50         elseif status == "success" then
  51                 --log("debug", "SUCCESS: %s", ret or "");
  52                 reply:text(base64.encode(ret or ""));
  53         else
  54                 module:log("error", "Unknown sasl status: %s", status);
  55         end
  56         return reply;
  57 end
  58
  59 local function handle_status(session, status, ret, err_msg)
  60         if status == "failure" then
  61                 session.sasl_handler = session.sasl_handler:clean_clone();
  62         elseif status == "success" then
  63                 local username = nodeprep(session.sasl_handler.username);
  64
  65                 local ok, err = sm_make_authenticated(session, session.sasl_handler.username);
  66                 if ok then
  67                         session.sasl_handler = nil;
  68                         session:reset_stream();
  69                 else
  70                         module:log("warn", "SASL succeeded but username was invalid");
  71                         session.sasl_handler = session.sasl_handler:clean_clone();
  72                         return "failure", "not-authorized", "User authenticated successfully, but username was invalid";
  73                 end
  74         end
  75         return status, ret, err_msg;
  76 end
  77
  78 local function sasl_process_cdata(session, stanza)
  79         local text = stanza[1];
  80         if text then
  81                 text = base64.decode(text);
  82                 --log("debug", "AUTH: %s", text:gsub("[%z\001-\008\011\012\014-\031]", " "));
  83                 if not text then
  84                         session.sasl_handler = nil;
  85                         session.send(build_reply("failure", "incorrect-encoding"));
  86                         return true;
  87                 end
  88         end
  89         local status, ret, err_msg = session.sasl_handler:process(text);
  90         status, ret, err_msg = handle_status(session, status, ret, err_msg);
  91         local s = build_reply(status, ret, err_msg);
  92         log("debug", "sasl reply: %s", tostring(s));
  93         session.send(s);
  94         return true;
  95 end
  96
  97 module:hook_stanza(xmlns_sasl, "success", function (session, stanza)
  98         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
  99         module:log("debug", "SASL EXTERNAL with %s succeeded", session.to_host);
 100         session.external_auth = "succeeded"
 101         session:reset_stream();
 102
 103         local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
 104                                     ["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
 105         session.sends2s("<?xml version='1.0'?>");
 106         session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
 107
 108         s2s_make_authenticated(session, session.to_host);
 109         return true;
 110 end)
 111
 112 module:hook_stanza(xmlns_sasl, "failure", function (session, stanza)
 113         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
 114
 115         module:log("info", "SASL EXTERNAL with %s failed", session.to_host)
 116         -- TODO: Log the failure reason
 117         session.external_auth = "failed"
 118 end, 500)
 119
 120 module:hook_stanza(xmlns_sasl, "failure", function (session, stanza)
 121         -- TODO: Dialback wasn't loaded.  Do something useful.
 122 end, 90)
 123
 124 module:hook_stanza("http://etherx.jabber.org/streams", "features", function (session, stanza)
 125         if session.type ~= "s2sout_unauthed" or not session.secure then return; end
 126
 127         local mechanisms = stanza:get_child("mechanisms", xmlns_sasl)
 128         if mechanisms then
 129                 for mech in mechanisms:childtags() do
 130                         if mech[1] == "EXTERNAL" then
 131                                 module:log("debug", "Initiating SASL EXTERNAL with %s", session.to_host);
 132                                 local reply = st.stanza("auth", {xmlns = xmlns_sasl, mechanism = "EXTERNAL"});
 133                                 reply:text(base64.encode(session.from_host))
 134                                 session.sends2s(reply)
 135                                 session.external_auth = "attempting"
 136                                 return true
 137                         end
 138                 end
 139         end
 140 end, 150);
 141
 142 local function s2s_external_auth(session, stanza)
 143         local mechanism = stanza.attr.mechanism;
 144
 145         if not session.secure then
 146                 if mechanism == "EXTERNAL" then
 147                         session.sends2s(build_reply("failure", "encryption-required"))
 148                 else
 149                         session.sends2s(build_reply("failure", "invalid-mechanism"))
 150                 end
 151                 return true;
 152         end
 153
 154         if mechanism ~= "EXTERNAL" or session.cert_chain_status ~= "valid" then
 155                 session.sends2s(build_reply("failure", "invalid-mechanism"))
 156                 return true;
 157         end
 158
 159         local text = stanza[1]
 160         if not text then
 161                 session.sends2s(build_reply("failure", "malformed-request"))
 162                 return true
 163         end
 164
 165         -- Either the value is "=" and we've already verified the external
 166         -- cert identity, or the value is a string and either matches the
 167         -- from_host (
 168
 169         text = base64.decode(text)
 170         if not text then
 171                 session.sends2s(build_reply("failure", "incorrect-encoding"))
 172                 return true;
 173         end
 174
 175         if session.cert_identity_status == "valid" then
 176                 if text ~= "" and text ~= session.from_host then
 177                         session.sends2s(build_reply("failure", "invalid-authzid"))
 178                         return true
 179                 end
 180         else
 181                 if text == "" then
 182                         session.sends2s(build_reply("failure", "invalid-authzid"))
 183                         return true
 184                 end
 185
 186                 local cert = session.conn:socket():getpeercertificate()
 187                 if (cert_verify_identity(text, "xmpp-server", cert)) then
 188                         session.cert_identity_status = "valid"
 189                 else
 190                         session.cert_identity_status = "invalid"
 191                         session.sends2s(build_reply("failure", "invalid-authzid"))
 192                         return true
 193                 end
 194         end
 195
 196         session.external_auth = "succeeded"
 197
 198         if not session.from_host then
 199                 session.from_host = text;
 200         end
 201         session.sends2s(build_reply("success"))
 202         module:log("info", "Accepting SASL EXTERNAL identity from %s", text or session.from_host);
 203         s2s_make_authenticated(session, text or session.from_host)
 204         session:reset_stream();
 205         return true
 206 end
 207
 208 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:auth", function(event)
 209         local session, stanza = event.origin, event.stanza;
 210         if session.type == "s2sin_unauthed" then
 211                 return s2s_external_auth(session, stanza)
 212         end
 213
 214         if session.type ~= "c2s_unauthed" then return; end
 215
 216         if session.sasl_handler and session.sasl_handler.selected then
 217                 session.sasl_handler = nil; -- allow starting a new SASL negotiation before completing an old one
 218         end
 219         if not session.sasl_handler then
 220                 if anonymous_login then
 221                         session.sasl_handler = new_sasl(module.host, anonymous_authentication_profile);
 222                 else
 223                         session.sasl_handler = usermanager_get_sasl_handler(module.host);
 224                 end
 225         end
 226         local mechanism = stanza.attr.mechanism;
 227         if anonymous_login then
 228                 if mechanism ~= "ANONYMOUS" then
 229                         session.send(build_reply("failure", "invalid-mechanism"));
 230                         return true;
 231                 end
 232         elseif mechanism == "ANONYMOUS" then
 233                 session.send(build_reply("failure", "mechanism-too-weak"));
 234                 return true;
 235         end
 236         if not session.secure and (secure_auth_only or (mechanism == "PLAIN" and not allow_unencrypted_plain_auth)) then
 237                 session.send(build_reply("failure", "encryption-required"));
 238                 return true;
 239         end
 240         local valid_mechanism = session.sasl_handler:select(mechanism);
 241         if not valid_mechanism then
 242                 session.send(build_reply("failure", "invalid-mechanism"));
 243                 return true;
 244         end
 245         return sasl_process_cdata(session, stanza);
 246 end);
 247 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:response", function(event)
 248         local session = event.origin;
 249         if not(session.sasl_handler and session.sasl_handler.selected) then
 250                 session.send(build_reply("failure", "not-authorized", "Out of order SASL element"));
 251                 return true;
 252         end
 253         return sasl_process_cdata(session, event.stanza);
 254 end);
 255 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:abort", function(event)
 256         local session = event.origin;
 257         session.sasl_handler = nil;
 258         session.send(build_reply("failure", "aborted"));
 259         return true;
 260 end);
 261
 262 local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };
 263 local bind_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-bind' };
 264 local xmpp_session_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-session' };
 265 module:hook("stream-features", function(event)
 266         local origin, features = event.origin, event.features;
 267         if not origin.username then
 268                 if secure_auth_only and not origin.secure then
 269                         return;
 270                 end
 271                 if anonymous_login then
 272                         origin.sasl_handler = new_sasl(module.host, anonymous_authentication_profile);
 273                 else
 274                         origin.sasl_handler = usermanager_get_sasl_handler(module.host);
 275                 end
 276                 features:tag("mechanisms", mechanisms_attr);
 277                 for mechanism in pairs(origin.sasl_handler:mechanisms()) do
 278                         if mechanism ~= "PLAIN" or origin.secure or allow_unencrypted_plain_auth then
 279                                 features:tag("mechanism"):text(mechanism):up();
 280                         end
 281                 end
 282                 features:up();
 283         else
 284                 features:tag("bind", bind_attr):tag("required"):up():up();
 285                 features:tag("session", xmpp_session_attr):tag("optional"):up():up();
 286         end
 287 end);
 288
 289 module:hook("s2s-stream-features", function(event)
 290         local origin, features = event.origin, event.features;
 291         if origin.secure and origin.type == "s2sin_unauthed" then
 292                 -- Offer EXTERNAL if chain is valid and either we didn't validate
 293                 -- the identity or it passed.
 294                 if origin.cert_chain_status == "valid" and origin.cert_identity_status ~= "invalid" then --TODO: Configurable
 295                         module:log("debug", "Offering SASL EXTERNAL")
 296                         features:tag("mechanisms", { xmlns = xmlns_sasl })
 297                                 :tag("mechanism"):text("EXTERNAL")
 298                         :up():up();
 299                 end
 300         end
 301 end);
 302
 303 module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-bind:bind", function(event)
 304         local origin, stanza = event.origin, event.stanza;
 305         local resource;
 306         if stanza.attr.type == "set" then
 307                 local bind = stanza.tags[1];
 308                 resource = bind:child_with_name("resource");
 309                 resource = resource and #resource.tags == 0 and resource[1] or nil;
 310         end
 311         local success, err_type, err, err_msg = sm_bind_resource(origin, resource);
 312         if success then
 313                 origin.send(st.reply(stanza)
 314                         :tag("bind", { xmlns = xmlns_bind })
 315                         :tag("jid"):text(origin.full_jid));
 316                 origin.log("debug", "Resource bound: %s", origin.full_jid);
 317         else
 318                 origin.send(st.error_reply(stanza, err_type, err, err_msg));
 319                 origin.log("debug", "Resource bind failed: %s", err_msg or err);
 320         end
 321         return true;
 322 end);
 323
 324 module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-session:session", function(event)
 325         event.origin.send(st.reply(event.stanza));
 326         return true;
 327 end);