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 sha256_hmac = require "util.hashes".hmac_sha256;
  16 local nameprep = require "util.encodings".stringprep.nameprep;
  17 local check_cert_status = module:depends"s2s".check_cert_status;
  18 local uuid_gen = require"util.uuid".generate;
  19
  20 local xmlns_stream = "http://etherx.jabber.org/streams";
  21
  22 local dialback_requests = setmetatable({}, { __mode = 'v' });
  23
  24 local dialback_secret = sha256_hash(module:get_option_string("dialback_secret", uuid_gen()), true);
  25 local dwd = module:get_option_boolean("dialback_without_dialback", false);
  26
  27 function module.save()
  28         return { dialback_secret = dialback_secret };
  29 end
  30
  31 function module.restore(state)
  32         dialback_secret = state.dialback_secret;
  33 end
  34
  35 function generate_dialback(id, to, from)
  36         return sha256_hmac(dialback_secret, to .. ' ' .. from .. ' ' .. id, true);
  37 end
  38
  39 function initiate_dialback(session)
  40         -- generate dialback key
  41         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  42         session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
  43         session.log("debug", "sent dialback key on outgoing s2s stream");
  44 end
  45
  46 function verify_dialback(id, to, from, key)
  47         return key == generate_dialback(id, to, from);
  48 end
  49
  50 module:hook("stanza/jabber:server:dialback:verify", function(event)
  51         local origin, stanza = event.origin, event.stanza;
  52
  53         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  54                 -- We are being asked to verify the key, to ensure it was generated by us
  55                 origin.log("debug", "verifying that dialback key is ours...");
  56                 local attr = stanza.attr;
  57                 if attr.type then
  58                         module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
  59                                 origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
  60                         return true;
  61                 end
  62                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  63                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  64                 local type;
  65                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  66                         type = "valid"
  67                 else
  68                         type = "invalid"
  69                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  70                 end
  71                 origin.log("debug", "verified dialback key... it is %s", type);
  72                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  73                 return true;
  74         end
  75 end);
  76
  77 module:hook("stanza/jabber:server:dialback:result", function(event)
  78         local origin, stanza = event.origin, event.stanza;
  79
  80         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  81                 -- he wants to be identified through dialback
  82                 -- We need to check the key with the Authoritative server
  83                 local attr = stanza.attr;
  84                 local to, from = nameprep(attr.to), nameprep(attr.from);
  85
  86                 if not hosts[to] then
  87                         -- Not a host that we serve
  88                         origin.log("warn", "%s tried to connect to %s, which we don't serve", from, to);
  89                         origin:close("host-unknown");
  90                         return true;
  91                 elseif not from then
  92                         origin:close("improper-addressing");
  93                 end
  94
  95                 if dwd and origin.secure then
  96                         if check_cert_status(origin, from) == false then
  97                                 return
  98                         elseif origin.cert_chain_status == "valid" and origin.cert_identity_status == "valid" then
  99                                 origin.sends2s(st.stanza("db:result", { to = from, from = to, id = attr.id, type = "valid" }));
 100                                 module:fire_event("s2s-authenticated", { session = origin, host = from });
 101                                 return true;
 102                         end
 103                 end
 104
 105                 origin.hosts[from] = { dialback_key = stanza[1] };
 106
 107                 dialback_requests[from.."/"..origin.streamid] = origin;
 108
 109                 -- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
 110                 -- on streams. We fill in the session's to/from here instead.
 111                 if not origin.from_host then
 112                         origin.from_host = from;
 113                 end
 114                 if not origin.to_host then
 115                         origin.to_host = to;
 116                 end
 117
 118                 origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
 119                 module:fire_event("route/remote", {
 120                         from_host = to, to_host = from;
 121                         stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
 122                 });
 123                 return true;
 124         end
 125 end);
 126
 127 module:hook("stanza/jabber:server:dialback:verify", function(event)
 128         local origin, stanza = event.origin, event.stanza;
 129
 130         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 131                 local attr = stanza.attr;
 132                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
 133                 if dialback_verifying and attr.from == origin.to_host then
 134                         local valid;
 135                         if attr.type == "valid" then
 136                                 module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from });
 137                                 valid = "valid";
 138                         else
 139                                 -- Warn the original connection that is was not verified successfully
 140                                 log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
 141                                 valid = "invalid";
 142                         end
 143                         if dialback_verifying.destroyed then
 144                                 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+$"));
 145                         else
 146                                 dialback_verifying.sends2s(
 147                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 148                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 149                         end
 150                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 151                 end
 152                 return true;
 153         end
 154 end);
 155
 156 module:hook("stanza/jabber:server:dialback:result", function(event)
 157         local origin, stanza = event.origin, event.stanza;
 158
 159         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 160                 -- Remote server is telling us whether we passed dialback
 161
 162                 local attr = stanza.attr;
 163                 if not hosts[attr.to] then
 164                         origin:close("host-unknown");
 165                         return true;
 166                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 167                         -- This isn't right
 168                         origin:close("invalid-id");
 169                         return true;
 170                 end
 171                 if stanza.attr.type == "valid" then
 172                         module:fire_event("s2s-authenticated", { session = origin, host = attr.from });
 173                 else
 174                         origin:close("not-authorized", "dialback authentication failed");
 175                 end
 176                 return true;
 177         end
 178 end);
 179
 180 module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
 181         if not origin.external_auth or origin.external_auth == "failed" then
 182                 module:log("debug", "Initiating dialback...");
 183                 initiate_dialback(origin);
 184                 return true;
 185         end
 186 end, 100);
 187
 188 module:hook("s2sout-authenticate-legacy", function (event)
 189         module:log("debug", "Initiating dialback...");
 190         initiate_dialback(event.origin);
 191         return true;
 192 end, 100);
 193
 194 -- Offer dialback to incoming hosts
 195 module:hook("s2s-stream-features", function (data)
 196         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 197 end);