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
  32 local function digest(self, message)
  33         --TODO complete support for authzid
  34
  35         local function serialize(message)
  36                 local data = ""
  37
  38                 if type(message) ~= "table" then error("serialize needs an argument of type table.") end
  39
  40                 -- testing all possible values
  41                 if message["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
  42                 if message["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
  43                 if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
  44                 if message["charset"] then data = data..[[charset=]]..message.charset.."," end
  45                 if message["algorithm"] then data = data..[[algorithm=]]..message.algorithm.."," end
  46                 if message["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
  47                 data = data:gsub(",$", "")
  48                 return data
  49         end
  50
  51         local function utf8tolatin1ifpossible(passwd)
  52                 local i = 1;
  53                 while i <= #passwd do
  54                         local passwd_i = to_byte(passwd:sub(i, i));
  55                         if passwd_i > 0x7F then
  56                                 if passwd_i < 0xC0 or passwd_i > 0xC3 then
  57                                         return passwd;
  58                                 end
  59                                 i = i + 1;
  60                                 passwd_i = to_byte(passwd:sub(i, i));
  61                                 if passwd_i < 0x80 or passwd_i > 0xBF then
  62                                         return passwd;
  63                                 end
  64                         end
  65                         i = i + 1;
  66                 end
  67
  68                 local p = {};
  69                 local j = 0;
  70                 i = 1;
  71                 while (i <= #passwd) do
  72                         local passwd_i = to_byte(passwd:sub(i, i));
  73                         if passwd_i > 0x7F then
  74                                 i = i + 1;
  75                                 local passwd_i_1 = to_byte(passwd:sub(i, i));
  76                                 t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
  77                         else
  78                                 t_insert(p, to_char(passwd_i));
  79                         end
  80                         i = i + 1;
  81                 end
  82                 return t_concat(p);
  83         end
  84         local function latin1toutf8(str)
  85                 local p = {};
  86                 for ch in s_gmatch(str, ".") do
  87                         ch = to_byte(ch);
  88                         if (ch < 0x80) then
  89                                 t_insert(p, to_char(ch));
  90                         elseif (ch < 0xC0) then
  91                                 t_insert(p, to_char(0xC2, ch));
  92                         else
  93                                 t_insert(p, to_char(0xC3, ch - 64));
  94                         end
  95                 end
  96                 return t_concat(p);
  97         end
  98         local function parse(data)
  99                 local message = {}
 100                 -- COMPAT: %z in the pattern to work around jwchat bug (sends "charset=utf-8\0")
 101                 for k, v in s_gmatch(data, [[([%w%-]+)="?([^",%z]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
 102                         message[k] = v;
 103                 end
 104                 return message;
 105         end
 106
 107         if not self.nonce then
 108                 self.nonce = generate_uuid();
 109                 self.step = 0;
 110                 self.nonce_count = {};
 111         end
 112
 113         self.step = self.step + 1;
 114         if (self.step == 1) then
 115                 local challenge = serialize({   nonce = self.nonce,
 116                                                                                 qop = "auth",
 117                                                                                 charset = "utf-8",
 118                                                                                 algorithm = "md5-sess",
 119                                                                                 realm = self.realm});
 120                 return "challenge", challenge;
 121         elseif (self.step == 2) then
 122                 local response = parse(message);
 123                 -- check for replay attack
 124                 if response["nc"] then
 125                         if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
 126                 end
 127
 128                 -- check for username, it's REQUIRED by RFC 2831
 129                 if not response["username"] then
 130                         return "failure", "malformed-request";
 131                 end
 132                 self["username"] = response["username"];
 133
 134                 -- check for nonce, ...
 135                 if not response["nonce"] then
 136                         return "failure", "malformed-request";
 137                 else
 138                         -- check if it's the right nonce
 139                         if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
 140                 end
 141
 142                 if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
 143                 if not response["qop"] then response["qop"] = "auth" end
 144
 145                 if response["realm"] == nil or response["realm"] == "" then
 146                         response["realm"] = "";
 147                 elseif response["realm"] ~= self.realm then
 148                         return "failure", "not-authorized", "Incorrect realm value";
 149                 end
 150
 151                 local decoder;
 152                 if response["charset"] == nil then
 153                         decoder = utf8tolatin1ifpossible;
 154                 elseif response["charset"] ~= "utf-8" then
 155                         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.";
 156                 end
 157
 158                 local domain = "";
 159                 local protocol = "";
 160                 if response["digest-uri"] then
 161                         protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
 162                         if protocol == nil or domain == nil then return "failure", "malformed-request" end
 163                 else
 164                         return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
 165                 end
 166
 167                 --TODO maybe realm support
 168                 self.username = response["username"];
 169                 if self.profile.plain then
 170                         local password, state = self.profile.plain(response["username"], self.realm)
 171                         if state == nil then return "failure", "not-authorized"
 172                         elseif state == false then return "failure", "account-disabled" end
 173                         local Y = md5(response["username"]..":"..response["realm"]..":"..password);
 174                 elseif self.profile["digest-md5"] then
 175                         local Y, state = self.profile["digest-md5"](response["username"], self.realm, response["realm"], response["charset"])
 176                         if state == nil then return "failure", "not-authorized"
 177                         elseif state == false then return "failure", "account-disabled" end
 178                 elseif self.profile["digest-md5-test"] then
 179                         -- TODO
 180                 end
 181                 --local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
 182                 --if Y == nil then return "failure", "not-authorized"
 183                 --elseif Y == false then return "failure", "account-disabled" end
 184                 local A1 = "";
 185                 if response.authzid then
 186                         if response.authzid == self.username or response.authzid == self.username.."@"..self.realm then
 187                                 -- COMPAT
 188                                 log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
 189                                 A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
 190                         else
 191                                 return "failure", "invalid-authzid";
 192                         end
 193                 else
 194                         A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
 195                 end
 196                 local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
 197
 198                 local HA1 = md5(A1, true);
 199                 local HA2 = md5(A2, true);
 200
 201                 local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
 202                 local response_value = md5(KD, true);
 203
 204                 if response_value == response["response"] then
 205                         -- calculate rspauth
 206                         A2 = ":"..protocol.."/"..domain;
 207
 208                         HA1 = md5(A1, true);
 209                         HA2 = md5(A2, true);
 210
 211                         KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
 212                         local rspauth = md5(KD, true);
 213                         self.authenticated = true;
 214                         return "success", serialize({rspauth = rspauth});
 215                 else
 216                         return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
 217                 end
 218         elseif self.step == 3 then
 219                 if self.authenticated ~= nil then return "success"
 220                 else return "failure", "malformed-request" end
 221         end
 222 end
 223
 224 function init(registerMechanism)
 225         registerMechanism("DIGEST-MD5", {"plain"}, digest);
 226 end
 227
 228 return _M;