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 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 = sha256_hash(module:get_option_string("dialback_secret", uuid_gen()), true);
  24 local dwd = module:get_option_boolean("dialback_without_dialback", false);
  25
  26 --- Helper to check that a session peer's certificate is valid
  27 function check_cert_status(session)
  28         local host = session.direction == "outgoing" and session.to_host or session.from_host
  29         local conn = session.conn:socket()
  30         local cert
  31         if conn.getpeercertificate then
  32                 cert = conn:getpeercertificate()
  33         end
  34
  35         return module:fire_event("s2s-check-certificate", { host = host, session = session, cert = cert });
  36 end
  37
  38
  39 function module.save()
  40         return { dialback_secret = dialback_secret };
  41 end
  42
  43 function module.restore(state)
  44         dialback_secret = state.dialback_secret;
  45 end
  46
  47 function generate_dialback(id, to, from)
  48         return sha256_hmac(dialback_secret, to .. ' ' .. from .. ' ' .. id, true);
  49 end
  50
  51 function initiate_dialback(session)
  52         -- generate dialback key
  53         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  54         session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
  55         session.log("debug", "sent dialback key on outgoing s2s stream");
  56 end
  57
  58 function verify_dialback(id, to, from, key)
  59         return key == generate_dialback(id, to, from);
  60 end
  61
  62 module:hook("stanza/jabber:server:dialback:verify", function(event)
  63         local origin, stanza = event.origin, event.stanza;
  64
  65         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  66                 -- We are being asked to verify the key, to ensure it was generated by us
  67                 origin.log("debug", "verifying that dialback key is ours...");
  68                 local attr = stanza.attr;
  69                 if attr.type then
  70                         module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
  71                                 origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
  72                         return true;
  73                 end
  74                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  75                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  76                 local type;
  77                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  78                         type = "valid"
  79                 else
  80                         type = "invalid"
  81                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  82                 end
  83                 origin.log("debug", "verified dialback key... it is %s", type);
  84                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  85                 return true;
  86         end
  87 end);
  88
  89 module:hook("stanza/jabber:server:dialback:result", function(event)
  90         local origin, stanza = event.origin, event.stanza;
  91
  92         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  93                 -- he wants to be identified through dialback
  94                 -- We need to check the key with the Authoritative server
  95                 local attr = stanza.attr;
  96                 local to, from = nameprep(attr.to), nameprep(attr.from);
  97
  98                 if not hosts[to] then
  99                         -- Not a host that we serve
 100                         origin.log("warn", "%s tried to connect to %s, which we don't serve", from, to);
 101                         origin:close("host-unknown");
 102                         return true;
 103                 elseif not from then
 104                         origin:close("improper-addressing");
 105                 end
 106
 107                 if dwd and origin.secure then
 108                         if check_cert_status(origin, from) == false then
 109                                 return
 110                         elseif origin.cert_chain_status == "valid" and origin.cert_identity_status == "valid" then
 111                                 origin.sends2s(st.stanza("db:result", { to = from, from = to, id = attr.id, type = "valid" }));
 112                                 module:fire_event("s2s-authenticated", { session = origin, host = from });
 113                                 return true;
 114                         end
 115                 end
 116
 117                 origin.hosts[from] = { dialback_key = stanza[1] };
 118
 119                 dialback_requests[from.."/"..origin.streamid] = origin;
 120
 121                 -- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
 122                 -- on streams. We fill in the session's to/from here instead.
 123                 if not origin.from_host then
 124                         origin.from_host = from;
 125                 end
 126                 if not origin.to_host then
 127                         origin.to_host = to;
 128                 end
 129
 130                 origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
 131                 module:fire_event("route/remote", {
 132                         from_host = to, to_host = from;
 133                         stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
 134                 });
 135                 return true;
 136         end
 137 end);
 138
 139 module:hook("stanza/jabber:server:dialback:verify", function(event)
 140         local origin, stanza = event.origin, event.stanza;
 141
 142         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 143                 local attr = stanza.attr;
 144                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
 145                 if dialback_verifying and attr.from == origin.to_host then
 146                         local valid;
 147                         if attr.type == "valid" then
 148                                 module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from });
 149                                 valid = "valid";
 150                         else
 151                                 -- Warn the original connection that is was not verified successfully
 152                                 log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
 153                                 valid = "invalid";
 154                         end
 155                         if dialback_verifying.destroyed then
 156                                 log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the dialback result",
 157                                         tostring(dialback_verifying):match("%w+$"));
 158                         else
 159                                 dialback_verifying.sends2s(
 160                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 161                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 162                         end
 163                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 164                 end
 165                 return true;
 166         end
 167 end);
 168
 169 module:hook("stanza/jabber:server:dialback:result", function(event)
 170         local origin, stanza = event.origin, event.stanza;
 171
 172         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 173                 -- Remote server is telling us whether we passed dialback
 174
 175                 local attr = stanza.attr;
 176                 if not hosts[attr.to] then
 177                         origin:close("host-unknown");
 178                         return true;
 179                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 180                         -- This isn't right
 181                         origin:close("invalid-id");
 182                         return true;
 183                 end
 184                 if stanza.attr.type == "valid" then
 185                         module:fire_event("s2s-authenticated", { session = origin, host = attr.from });
 186                 else
 187                         origin:close("not-authorized", "dialback authentication failed");
 188                 end
 189                 return true;
 190         end
 191 end);
 192
 193 module:hook_tag("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza) -- luacheck: ignore 212/stanza
 194         if origin.external_auth == "failed" then
 195                 module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
 196                 initiate_dialback(origin);
 197                 return true;
 198         end
 199 end, 100);
 200
 201 module:hook_tag(xmlns_stream, "features", function (origin, stanza) -- luacheck: ignore 212/stanza
 202         if not origin.external_auth or origin.external_auth == "failed" then
 203                 module:log("debug", "Initiating dialback...");
 204                 initiate_dialback(origin);
 205                 return true;
 206         end
 207 end, 100);
 208
 209 module:hook("s2sout-authenticate-legacy", function (event)
 210         module:log("debug", "Initiating dialback...");
 211         initiate_dialback(event.origin);
 212         return true;
 213 end, 100);
 214
 215 -- Offer dialback to incoming hosts
 216 module:hook("s2s-stream-features", function (data)
 217         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 218 end);