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