plugins/mod_dialback.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 local hosts = _G.hosts;
  10
  11 local log = module._log;
  12
  13 local st = require "util.stanza";
  14 local sha256_hash = require "util.hashes".sha256;
  15 local nameprep = require "util.encodings".stringprep.nameprep;
  16 local check_cert_status = module:depends"s2s".check_cert_status;
  17 local uuid_gen = require"util.uuid".generate;
  18
  19 local xmlns_stream = "http://etherx.jabber.org/streams";
  20
  21 local dialback_requests = setmetatable({}, { __mode = 'v' });
  22
  23 local dialback_secret = module.host .. module:get_option_string("dialback_secret", uuid_gen());
  24 local dwd = module:get_option_boolean("dialback_without_dialback", false);
  25
  26 function module.save()
  27         return { dialback_secret = dialback_secret };
  28 end
  29
  30 function module.restore(state)
  31         dialback_secret = state.dialback_secret;
  32 end
  33
  34 function generate_dialback(id, to, from)
  35         return sha256_hash(id..to..dialback_secret, true);
  36 end
  37
  38 function initiate_dialback(session)
  39         -- generate dialback key
  40         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  41         session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
  42         session.log("debug", "sent dialback key on outgoing s2s stream");
  43 end
  44
  45 function verify_dialback(id, to, from, key)
  46         return key == generate_dialback(id, to, from);
  47 end
  48
  49 module:hook("stanza/jabber:server:dialback:verify", function(event)
  50         local origin, stanza = event.origin, event.stanza;
  51
  52         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  53                 -- We are being asked to verify the key, to ensure it was generated by us
  54                 origin.log("debug", "verifying that dialback key is ours...");
  55                 local attr = stanza.attr;
  56                 if attr.type then
  57                         module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
  58                                 origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
  59                         return true;
  60                 end
  61                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  62                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  63                 local type;
  64                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  65                         type = "valid"
  66                 else
  67                         type = "invalid"
  68                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  69                 end
  70                 origin.log("debug", "verified dialback key... it is %s", type);
  71                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  72                 return true;
  73         end
  74 end);
  75
  76 module:hook("stanza/jabber:server:dialback:result", function(event)
  77         local origin, stanza = event.origin, event.stanza;
  78
  79         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  80                 -- he wants to be identified through dialback
  81                 -- We need to check the key with the Authoritative server
  82                 local attr = stanza.attr;
  83                 local to, from = nameprep(attr.to), nameprep(attr.from);
  84
  85                 if check_cert_status(origin, from) == false then
  86                         return
  87                 elseif origin.cert_chain_status == "valid" and origin.cert_identity_status == "valid" then
  88                         origin.sends2s(st.stanza("db:result", { to = from, from = to, id = attr.id, type = "valid" }));
  89                         module:fire_event("s2s-authenticated", { session = origin, host = from });
  90                         return true;
  91                 end
  92
  93                 if not hosts[to] then
  94                         -- Not a host that we serve
  95                         origin.log("warn", "%s tried to connect to %s, which we don't serve", from, to);
  96                         origin:close("host-unknown");
  97                         return true;
  98                 elseif not from then
  99                         origin:close("improper-addressing");
 100                 end
 101
 102                 origin.hosts[from] = { dialback_key = stanza[1] };
 103
 104                 dialback_requests[from.."/"..origin.streamid] = origin;
 105
 106                 -- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
 107                 -- on streams. We fill in the session's to/from here instead.
 108                 if not origin.from_host then
 109                         origin.from_host = from;
 110                 end
 111                 if not origin.to_host then
 112                         origin.to_host = to;
 113                 end
 114
 115                 origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
 116                 module:fire_event("route/remote", {
 117                         from_host = to, to_host = from;
 118                         stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
 119                 });
 120                 return true;
 121         end
 122 end);
 123
 124 module:hook("stanza/jabber:server:dialback:verify", function(event)
 125         local origin, stanza = event.origin, event.stanza;
 126
 127         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 128                 local attr = stanza.attr;
 129                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
 130                 if dialback_verifying and attr.from == origin.to_host then
 131                         local valid;
 132                         if attr.type == "valid" then
 133                                 module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from });
 134                                 valid = "valid";
 135                         else
 136                                 -- Warn the original connection that is was not verified successfully
 137                                 log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
 138                                 valid = "invalid";
 139                         end
 140                         if dialback_verifying.destroyed then
 141                                 log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the db result", tostring(dialback_verifying):match("%w+$"));
 142                         else
 143                                 dialback_verifying.sends2s(
 144                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 145                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 146                         end
 147                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 148                 end
 149                 return true;
 150         end
 151 end);
 152
 153 module:hook("stanza/jabber:server:dialback:result", function(event)
 154         local origin, stanza = event.origin, event.stanza;
 155
 156         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 157                 -- Remote server is telling us whether we passed dialback
 158
 159                 local attr = stanza.attr;
 160                 if not hosts[attr.to] then
 161                         origin:close("host-unknown");
 162                         return true;
 163                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 164                         -- This isn't right
 165                         origin:close("invalid-id");
 166                         return true;
 167                 end
 168                 if stanza.attr.type == "valid" then
 169                         module:fire_event("s2s-authenticated", { session = origin, host = attr.from });
 170                 else
 171                         origin:close("not-authorized", "dialback authentication failed");
 172                 end
 173                 return true;
 174         end
 175 end);
 176
 177 module:hook_stanza("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza)
 178         if origin.external_auth == "failed" then
 179                 module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
 180                 initiate_dialback(origin);
 181                 return true;
 182         end
 183 end, 100);
 184
 185 module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
 186         if not origin.external_auth or origin.external_auth == "failed" then
 187                 module:log("debug", "Initiating dialback...");
 188                 initiate_dialback(origin);
 189                 return true;
 190         end
 191 end, 100);
 192
 193 module:hook("s2sout-authenticate-legacy", function (event)
 194         module:log("debug", "Initiating dialback...");
 195         initiate_dialback(event.origin);
 196         return true;
 197 end, 100);
 198
 199 -- Offer dialback to incoming hosts
 200 module:hook("s2s-stream-features", function (data)
 201         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 202 end);