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