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.x509".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 tostring = tostring;
  22
  23 local secure_auth_only = module:get_option("c2s_require_encryption") or module:get_option("require_encryption");
  24 local allow_unencrypted_plain_auth = module:get_option("allow_unencrypted_plain_auth")
  25
  26 local log = module._log;
  27
  28 local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';
  29 local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';
  30 local xmlns_stanzas ='urn:ietf:params:xml:ns:xmpp-stanzas';
  31
  32 local function build_reply(status, ret, err_msg)
  33         local reply = st.stanza(status, {xmlns = xmlns_sasl});
  34         if status == "challenge" then
  35                 --log("debug", "CHALLENGE: %s", ret or "");
  36                 reply:text(base64.encode(ret or ""));
  37         elseif status == "failure" then
  38                 reply:tag(ret):up();
  39                 if err_msg then reply:tag("text"):text(err_msg); end
  40         elseif status == "success" then
  41                 --log("debug", "SUCCESS: %s", ret or "");
  42                 reply:text(base64.encode(ret or ""));
  43         else
  44                 module:log("error", "Unknown sasl status: %s", status);
  45         end
  46         return reply;
  47 end
  48
  49 local function handle_status(session, status, ret, err_msg)
  50         if status == "failure" then
  51                 session.sasl_handler = session.sasl_handler:clean_clone();
  52         elseif status == "success" then
  53                 local username = nodeprep(session.sasl_handler.username);
  54
  55                 local ok, err = sm_make_authenticated(session, session.sasl_handler.username);
  56                 if ok then
  57                         session.sasl_handler = nil;
  58                         session:reset_stream();
  59                 else
  60                         module:log("warn", "SASL succeeded but username was invalid");
  61                         session.sasl_handler = session.sasl_handler:clean_clone();
  62                         return "failure", "not-authorized", "User authenticated successfully, but username was invalid";
  63                 end
  64         end
  65         return status, ret, err_msg;
  66 end
  67
  68 local function sasl_process_cdata(session, stanza)
  69         local text = stanza[1];
  70         if text then
  71                 text = base64.decode(text);
  72                 --log("debug", "AUTH: %s", text:gsub("[%z\001-\008\011\012\014-\031]", " "));
  73                 if not text then
  74                         session.sasl_handler = nil;
  75                         session.send(build_reply("failure", "incorrect-encoding"));
  76                         return true;
  77                 end
  78         end
  79         local status, ret, err_msg = session.sasl_handler:process(text);
  80         status, ret, err_msg = handle_status(session, status, ret, err_msg);
  81         local s = build_reply(status, ret, err_msg);
  82         log("debug", "sasl reply: %s", tostring(s));
  83         session.send(s);
  84         return true;
  85 end
  86
  87 module:hook_stanza(xmlns_sasl, "success", function (session, stanza)
  88         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
  89         module:log("debug", "SASL EXTERNAL with %s succeeded", session.to_host);
  90         session.external_auth = "succeeded"
  91         session:reset_stream();
  92
  93         local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
  94                                     ["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
  95         session.sends2s("<?xml version='1.0'?>");
  96         session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
  97
  98         s2s_make_authenticated(session, session.to_host);
  99         return true;
 100 end)
 101
 102 module:hook_stanza(xmlns_sasl, "failure", function (session, stanza)
 103         if session.type ~= "s2sout_unauthed" or session.external_auth ~= "attempting" then return; end
 104
 105         module:log("info", "SASL EXTERNAL with %s failed", session.to_host)
 106         -- TODO: Log the failure reason
 107         session.external_auth = "failed"
 108 end, 500)
 109
 110 module:hook_stanza(xmlns_sasl, "failure", function (session, stanza)
 111         -- TODO: Dialback wasn't loaded.  Do something useful.
 112 end, 90)
 113
 114 module:hook_stanza("http://etherx.jabber.org/streams", "features", function (session, stanza)
 115         if session.type ~= "s2sout_unauthed" or not session.secure then return; end
 116
 117         local mechanisms = stanza:get_child("mechanisms", xmlns_sasl)
 118         if mechanisms then
 119                 for mech in mechanisms:childtags() do
 120                         if mech[1] == "EXTERNAL" then
 121                                 module:log("debug", "Initiating SASL EXTERNAL with %s", session.to_host);
 122                                 local reply = st.stanza("auth", {xmlns = xmlns_sasl, mechanism = "EXTERNAL"});
 123                                 reply:text(base64.encode(session.from_host))
 124                                 session.sends2s(reply)
 125                                 session.external_auth = "attempting"
 126                                 return true
 127                         end
 128                 end
 129         end
 130 end, 150);
 131
 132 local function s2s_external_auth(session, stanza)
 133         local mechanism = stanza.attr.mechanism;
 134
 135         if not session.secure then
 136                 if mechanism == "EXTERNAL" then
 137                         session.sends2s(build_reply("failure", "encryption-required"))
 138                 else
 139                         session.sends2s(build_reply("failure", "invalid-mechanism"))
 140                 end
 141                 return true;
 142         end
 143
 144         if mechanism ~= "EXTERNAL" or session.cert_chain_status ~= "valid" then
 145                 session.sends2s(build_reply("failure", "invalid-mechanism"))
 146                 return true;
 147         end
 148
 149         local text = stanza[1]
 150         if not text then
 151                 session.sends2s(build_reply("failure", "malformed-request"))
 152                 return true
 153         end
 154
 155         -- Either the value is "=" and we've already verified the external
 156         -- cert identity, or the value is a string and either matches the
 157         -- from_host (
 158
 159         text = base64.decode(text)
 160         if not text then
 161                 session.sends2s(build_reply("failure", "incorrect-encoding"))
 162                 return true;
 163         end
 164
 165         if session.cert_identity_status == "valid" then
 166                 if text ~= "" and text ~= session.from_host then
 167                         session.sends2s(build_reply("failure", "invalid-authzid"))
 168                         return true
 169                 end
 170         else
 171                 if text == "" then
 172                         session.sends2s(build_reply("failure", "invalid-authzid"))
 173                         return true
 174                 end
 175
 176                 local cert = session.conn:socket():getpeercertificate()
 177                 if (cert_verify_identity(text, "xmpp-server", cert)) then
 178                         session.cert_identity_status = "valid"
 179                 else
 180                         session.cert_identity_status = "invalid"
 181                         session.sends2s(build_reply("failure", "invalid-authzid"))
 182                         return true
 183                 end
 184         end
 185
 186         session.external_auth = "succeeded"
 187
 188         if not session.from_host then
 189                 session.from_host = text;
 190         end
 191         session.sends2s(build_reply("success"))
 192         module:log("info", "Accepting SASL EXTERNAL identity from %s", text or session.from_host);
 193         s2s_make_authenticated(session, text or session.from_host)
 194         session:reset_stream();
 195         return true
 196 end
 197
 198 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:auth", function(event)
 199         local session, stanza = event.origin, event.stanza;
 200         if session.type == "s2sin_unauthed" then
 201                 return s2s_external_auth(session, stanza)
 202         end
 203
 204         if session.type ~= "c2s_unauthed" then return; end
 205
 206         if session.sasl_handler and session.sasl_handler.selected then
 207                 session.sasl_handler = nil; -- allow starting a new SASL negotiation before completing an old one
 208         end
 209         if not session.sasl_handler then
 210                 session.sasl_handler = usermanager_get_sasl_handler(module.host);
 211         end
 212         local mechanism = stanza.attr.mechanism;
 213         if not session.secure and (secure_auth_only or (mechanism == "PLAIN" and not allow_unencrypted_plain_auth)) then
 214                 session.send(build_reply("failure", "encryption-required"));
 215                 return true;
 216         end
 217         local valid_mechanism = session.sasl_handler:select(mechanism);
 218         if not valid_mechanism then
 219                 session.send(build_reply("failure", "invalid-mechanism"));
 220                 return true;
 221         end
 222         return sasl_process_cdata(session, stanza);
 223 end);
 224 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:response", function(event)
 225         local session = event.origin;
 226         if not(session.sasl_handler and session.sasl_handler.selected) then
 227                 session.send(build_reply("failure", "not-authorized", "Out of order SASL element"));
 228                 return true;
 229         end
 230         return sasl_process_cdata(session, event.stanza);
 231 end);
 232 module:hook("stanza/urn:ietf:params:xml:ns:xmpp-sasl:abort", function(event)
 233         local session = event.origin;
 234         session.sasl_handler = nil;
 235         session.send(build_reply("failure", "aborted"));
 236         return true;
 237 end);
 238
 239 local mechanisms_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-sasl' };
 240 local bind_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-bind' };
 241 local xmpp_session_attr = { xmlns='urn:ietf:params:xml:ns:xmpp-session' };
 242 module:hook("stream-features", function(event)
 243         local origin, features = event.origin, event.features;
 244         if not origin.username then
 245                 if secure_auth_only and not origin.secure then
 246                         return;
 247                 end
 248                 origin.sasl_handler = usermanager_get_sasl_handler(module.host);
 249                 features:tag("mechanisms", mechanisms_attr);
 250                 for mechanism in pairs(origin.sasl_handler:mechanisms()) do
 251                         if mechanism ~= "PLAIN" or origin.secure or allow_unencrypted_plain_auth then
 252                                 features:tag("mechanism"):text(mechanism):up();
 253                         end
 254                 end
 255                 features:up();
 256         else
 257                 features:tag("bind", bind_attr):tag("required"):up():up();
 258                 features:tag("session", xmpp_session_attr):tag("optional"):up():up();
 259         end
 260 end);
 261
 262 module:hook("s2s-stream-features", function(event)
 263         local origin, features = event.origin, event.features;
 264         if origin.secure and origin.type == "s2sin_unauthed" then
 265                 -- Offer EXTERNAL if chain is valid and either we didn't validate
 266                 -- the identity or it passed.
 267                 if origin.cert_chain_status == "valid" and origin.cert_identity_status ~= "invalid" then --TODO: Configurable
 268                         module:log("debug", "Offering SASL EXTERNAL")
 269                         features:tag("mechanisms", { xmlns = xmlns_sasl })
 270                                 :tag("mechanism"):text("EXTERNAL")
 271                         :up():up();
 272                 end
 273         end
 274 end);
 275
 276 module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-bind:bind", function(event)
 277         local origin, stanza = event.origin, event.stanza;
 278         local resource;
 279         if stanza.attr.type == "set" then
 280                 local bind = stanza.tags[1];
 281                 resource = bind:child_with_name("resource");
 282                 resource = resource and #resource.tags == 0 and resource[1] or nil;
 283         end
 284         local success, err_type, err, err_msg = sm_bind_resource(origin, resource);
 285         if success then
 286                 origin.send(st.reply(stanza)
 287                         :tag("bind", { xmlns = xmlns_bind })
 288                         :tag("jid"):text(origin.full_jid));
 289                 origin.log("debug", "Resource bound: %s", origin.full_jid);
 290         else
 291                 origin.send(st.error_reply(stanza, err_type, err, err_msg));
 292                 origin.log("debug", "Resource bind failed: %s", err_msg or err);
 293         end
 294         return true;
 295 end);
 296
 297 local function handle_legacy_session(event)
 298         event.origin.send(st.reply(event.stanza));
 299         return true;
 300 end
 301
 302 module:hook("iq/self/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);
 303 module:hook("iq/host/urn:ietf:params:xml:ns:xmpp-session:session", handle_legacy_session);