util/sasl/digest-md5.lua

   1 -- sasl.lua v0.4
   2 -- Copyright (C) 2008-2009 Tobias Markmann
   3 --
   4 --    All rights reserved.
   5 --
   6 --    Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
   7 --
   8 --        * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
   9 --        * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  10 --        * Neither the name of Tobias Markmann nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
  11 --
  12 --    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  13
  14 local tostring = tostring;
  15 local type = type;
  16
  17 local s_gmatch = string.gmatch;
  18 local s_match = string.match;
  19 local t_concat = table.concat;
  20 local t_insert = table.insert;
  21 local to_byte, to_char = string.byte, string.char;
  22
  23 local md5 = require "util.hashes".md5;
  24 local log = require "util.logger".init("sasl");
  25 local generate_uuid = require "util.uuid".generate;
  26
  27 module "digest-md5"
  28
  29 --=========================
  30 --SASL DIGEST-MD5 according to RFC 2831
  31 local function digest_response()
  32
  33         return response, A1, A2
  34 end
  35
  36 local function digest(self, message)
  37         --TODO complete support for authzid
  38
  39         local function serialize(message)
  40                 local data = ""
  41
  42                 if type(message) ~= "table" then error("serialize needs an argument of type table.") end
  43
  44                 -- testing all possible values
  45                 if message["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
  46                 if message["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
  47                 if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
  48                 if message["charset"] then data = data..[[charset=]]..message.charset.."," end
  49                 if message["algorithm"] then data = data..[[algorithm=]]..message.algorithm.."," end
  50                 if message["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
  51                 data = data:gsub(",$", "")
  52                 return data
  53         end
  54
  55         local function utf8tolatin1ifpossible(passwd)
  56                 local i = 1;
  57                 while i <= #passwd do
  58                         local passwd_i = to_byte(passwd:sub(i, i));
  59                         if passwd_i > 0x7F then
  60                                 if passwd_i < 0xC0 or passwd_i > 0xC3 then
  61                                         return passwd;
  62                                 end
  63                                 i = i + 1;
  64                                 passwd_i = to_byte(passwd:sub(i, i));
  65                                 if passwd_i < 0x80 or passwd_i > 0xBF then
  66                                         return passwd;
  67                                 end
  68                         end
  69                         i = i + 1;
  70                 end
  71
  72                 local p = {};
  73                 local j = 0;
  74                 i = 1;
  75                 while (i <= #passwd) do
  76                         local passwd_i = to_byte(passwd:sub(i, i));
  77                         if passwd_i > 0x7F then
  78                                 i = i + 1;
  79                                 local passwd_i_1 = to_byte(passwd:sub(i, i));
  80                                 t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
  81                         else
  82                                 t_insert(p, to_char(passwd_i));
  83                         end
  84                         i = i + 1;
  85                 end
  86                 return t_concat(p);
  87         end
  88         local function latin1toutf8(str)
  89                 local p = {};
  90                 for ch in s_gmatch(str, ".") do
  91                         ch = to_byte(ch);
  92                         if (ch < 0x80) then
  93                                 t_insert(p, to_char(ch));
  94                         elseif (ch < 0xC0) then
  95                                 t_insert(p, to_char(0xC2, ch));
  96                         else
  97                                 t_insert(p, to_char(0xC3, ch - 64));
  98                         end
  99                 end
 100                 return t_concat(p);
 101         end
 102         local function parse(data)
 103                 local message = {}
 104                 -- COMPAT: %z in the pattern to work around jwchat bug (sends "charset=utf-8\0")
 105                 for k, v in s_gmatch(data, [[([%w%-]+)="?([^",%z]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
 106                         message[k] = v;
 107                 end
 108                 return message;
 109         end
 110
 111         if not self.nonce then
 112                 self.nonce = generate_uuid();
 113                 self.step = 0;
 114                 self.nonce_count = {};
 115         end
 116
 117         self.step = self.step + 1;
 118         if (self.step == 1) then
 119                 local challenge = serialize({   nonce = self.nonce,
 120                                                                                 qop = "auth",
 121                                                                                 charset = "utf-8",
 122                                                                                 algorithm = "md5-sess",
 123                                                                                 realm = self.realm});
 124                 return "challenge", challenge;
 125         elseif (self.step == 2) then
 126                 local response = parse(message);
 127                 -- check for replay attack
 128                 if response["nc"] then
 129                         if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
 130                 end
 131
 132                 -- check for username, it's REQUIRED by RFC 2831
 133                 if not response["username"] then
 134                         return "failure", "malformed-request";
 135                 end
 136                 self["username"] = response["username"];
 137
 138                 -- check for nonce, ...
 139                 if not response["nonce"] then
 140                         return "failure", "malformed-request";
 141                 else
 142                         -- check if it's the right nonce
 143                         if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
 144                 end
 145
 146                 if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
 147                 if not response["qop"] then response["qop"] = "auth" end
 148
 149                 if response["realm"] == nil or response["realm"] == "" then
 150                         response["realm"] = "";
 151                 elseif response["realm"] ~= self.realm then
 152                         return "failure", "not-authorized", "Incorrect realm value";
 153                 end
 154
 155                 local decoder;
 156                 if response["charset"] == nil then
 157                         decoder = utf8tolatin1ifpossible;
 158                 elseif response["charset"] ~= "utf-8" then
 159                         return "failure", "incorrect-encoding", "The client's response uses "..response["charset"].." for encoding with isn't supported by sasl.lua. Supported encodings are latin or utf-8.";
 160                 end
 161
 162                 local domain = "";
 163                 local protocol = "";
 164                 if response["digest-uri"] then
 165                         protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
 166                         if protocol == nil or domain == nil then return "failure", "malformed-request" end
 167                 else
 168                         return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
 169                 end
 170
 171                 --TODO maybe realm support
 172                 self.username = response["username"];
 173                 if self.profile.plain then
 174                         local password, state = self.profile.plain(response["username"], self.realm)
 175                         if state == nil then return "failure", "not-authorized"
 176                         elseif state == false then return "failure", "account-disabled" end
 177                         Y = md5(response["username"]..":"..response["realm"]..":"..password);
 178                 elseif self.profile["digest-md5"] then
 179                         local Y, state = self.profile["digest-md5"](response["username"], self.realm, response["realm"], response["charset"])
 180                         if state == nil then return "failure", "not-authorized"
 181                         elseif state == false then return "failure", "account-disabled" end
 182                 elseif self.profile["digest-md5-test"] then
 183                         -- TODO
 184                 end
 185                 --local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
 186                 --if Y == nil then return "failure", "not-authorized"
 187                 --elseif Y == false then return "failure", "account-disabled" end
 188                 local A1 = "";
 189                 if response.authzid then
 190                         if response.authzid == self.username or response.authzid == self.username.."@"..self.realm then
 191                                 -- COMPAT
 192                                 log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
 193                                 A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
 194                         else
 195                                 return "failure", "invalid-authzid";
 196                         end
 197                 else
 198                         A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
 199                 end
 200                 local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
 201
 202                 local HA1 = md5(A1, true);
 203                 local HA2 = md5(A2, true);
 204
 205                 local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
 206                 local response_value = md5(KD, true);
 207
 208                 if response_value == response["response"] then
 209                         -- calculate rspauth
 210                         A2 = ":"..protocol.."/"..domain;
 211
 212                         HA1 = md5(A1, true);
 213                         HA2 = md5(A2, true);
 214
 215                         KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
 216                         local rspauth = md5(KD, true);
 217                         self.authenticated = true;
 218                         return "success", serialize({rspauth = rspauth});
 219                 else
 220                         return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
 221                 end
 222         elseif self.step == 3 then
 223                 if self.authenticated ~= nil then return "success"
 224                 else return "failure", "malformed-request" end
 225         end
 226 end
 227
 228 function init(registerMechanism)
 229         registerMechanism("DIGEST-MD5", {"plain"}, digest);
 230 end
 231
 232 return _M;