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                 for k, v in s_gmatch(data, [[([%w%-]+)="?([^",]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
 105                         message[k] = v;
 106                 end
 107                 return message;
 108         end
 109
 110         if not self.nonce then
 111                 self.nonce = generate_uuid();
 112                 self.step = 0;
 113                 self.nonce_count = {};
 114         end
 115
 116         self.step = self.step + 1;
 117         if (self.step == 1) then
 118                 local challenge = serialize({   nonce = self.nonce,
 119                                                                                 qop = "auth",
 120                                                                                 charset = "utf-8",
 121                                                                                 algorithm = "md5-sess",
 122                                                                                 realm = self.realm});
 123                 return "challenge", challenge;
 124         elseif (self.step == 2) then
 125                 local response = parse(message);
 126                 -- check for replay attack
 127                 if response["nc"] then
 128                         if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
 129                 end
 130
 131                 -- check for username, it's REQUIRED by RFC 2831
 132                 if not response["username"] then
 133                         return "failure", "malformed-request";
 134                 end
 135                 self["username"] = response["username"];
 136
 137                 -- check for nonce, ...
 138                 if not response["nonce"] then
 139                         return "failure", "malformed-request";
 140                 else
 141                         -- check if it's the right nonce
 142                         if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
 143                 end
 144
 145                 if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
 146                 if not response["qop"] then response["qop"] = "auth" end
 147
 148                 if response["realm"] == nil or response["realm"] == "" then
 149                         response["realm"] = "";
 150                 elseif response["realm"] ~= self.realm then
 151                         return "failure", "not-authorized", "Incorrect realm value";
 152                 end
 153
 154                 local decoder;
 155                 if response["charset"] == nil then
 156                         decoder = utf8tolatin1ifpossible;
 157                 elseif response["charset"] ~= "utf-8" then
 158                         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.";
 159                 end
 160
 161                 local domain = "";
 162                 local protocol = "";
 163                 if response["digest-uri"] then
 164                         protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
 165                         if protocol == nil or domain == nil then return "failure", "malformed-request" end
 166                 else
 167                         return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
 168                 end
 169
 170                 --TODO maybe realm support
 171                 self.username = response["username"];
 172                 if self.profile.plain then
 173                         local password, state = self.profile.plain(response["username"], self.realm)
 174                         if state == nil then return "failure", "not-authorized"
 175                         elseif state == false then return "failure", "account-disabled" end
 176                         Y = md5(response["username"]..":"..response["realm"]..":"..password);
 177                 elseif self.profile["digest-md5"] then
 178                         local Y, state = self.profile["digest-md5"](response["username"], self.realm, response["realm"], response["charset"])
 179                         if state == nil then return "failure", "not-authorized"
 180                         elseif state == false then return "failure", "account-disabled" end
 181                 elseif self.profile["digest-md5-test"] then
 182                         -- TODO
 183                 end
 184                 --local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
 185                 --if Y == nil then return "failure", "not-authorized"
 186                 --elseif Y == false then return "failure", "account-disabled" end
 187                 local A1 = "";
 188                 if response.authzid then
 189                         if response.authzid == self.username or response.authzid == self.username.."@"..self.realm then
 190                                 -- COMPAT
 191                                 log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
 192                                 A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
 193                         else
 194                                 return "failure", "invalid-authzid";
 195                         end
 196                 else
 197                         A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
 198                 end
 199                 local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
 200
 201                 local HA1 = md5(A1, true);
 202                 local HA2 = md5(A2, true);
 203
 204                 local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
 205                 local response_value = md5(KD, true);
 206
 207                 if response_value == response["response"] then
 208                         -- calculate rspauth
 209                         A2 = ":"..protocol.."/"..domain;
 210
 211                         HA1 = md5(A1, true);
 212                         HA2 = md5(A2, true);
 213
 214                         KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
 215                         local rspauth = md5(KD, true);
 216                         self.authenticated = true;
 217                         --TODO: considering sending the rspauth in a success node for saving one roundtrip; allowed according to http://tools.ietf.org/html/draft-saintandre-rfc3920bis-09#section-7.3.6
 218                         return "challenge", 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;