util/sasl/digest-md5.lua

   1 -- sasl.lua v0.4
   2 -- Copyright (C) 2008-2010 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 local nodeprep = require "util.encodings".stringprep.nodeprep;
  27
  28 local _ENV = nil;
  29 -- luacheck: std none
  30
  31 --=========================
  32 --SASL DIGEST-MD5 according to RFC 2831
  33
  34 --[[
  35 Supported Authentication Backends
  36
  37 digest_md5:
  38         function(username, domain, realm, encoding) -- domain and realm are usually the same; for some broken
  39                                                                                                 -- implementations it's not
  40                 return digesthash, state;
  41         end
  42
  43 digest_md5_test:
  44         function(username, domain, realm, encoding, digesthash)
  45                 return true or false, state;
  46         end
  47 ]]
  48
  49 local function digest(self, message)
  50         --TODO complete support for authzid
  51
  52         local function serialize(message)
  53                 local data = ""
  54
  55                 -- testing all possible values
  56                 if message["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
  57                 if message["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
  58                 if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
  59                 if message["charset"] then data = data..[[charset=]]..message.charset.."," end
  60                 if message["algorithm"] then data = data..[[algorithm=]]..message.algorithm.."," end
  61                 if message["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
  62                 data = data:gsub(",$", "")
  63                 return data
  64         end
  65
  66         local function utf8tolatin1ifpossible(passwd)
  67                 local i = 1;
  68                 while i <= #passwd do
  69                         local passwd_i = to_byte(passwd:sub(i, i));
  70                         if passwd_i > 0x7F then
  71                                 if passwd_i < 0xC0 or passwd_i > 0xC3 then
  72                                         return passwd;
  73                                 end
  74                                 i = i + 1;
  75                                 passwd_i = to_byte(passwd:sub(i, i));
  76                                 if passwd_i < 0x80 or passwd_i > 0xBF then
  77                                         return passwd;
  78                                 end
  79                         end
  80                         i = i + 1;
  81                 end
  82
  83                 local p = {};
  84                 local j = 0;
  85                 i = 1;
  86                 while (i <= #passwd) do
  87                         local passwd_i = to_byte(passwd:sub(i, i));
  88                         if passwd_i > 0x7F then
  89                                 i = i + 1;
  90                                 local passwd_i_1 = to_byte(passwd:sub(i, i));
  91                                 t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
  92                         else
  93                                 t_insert(p, to_char(passwd_i));
  94                         end
  95                         i = i + 1;
  96                 end
  97                 return t_concat(p);
  98         end
  99         local function latin1toutf8(str)
 100                 local p = {};
 101                 for ch in s_gmatch(str, ".") do
 102                         ch = to_byte(ch);
 103                         if (ch < 0x80) then
 104                                 t_insert(p, to_char(ch));
 105                         elseif (ch < 0xC0) then
 106                                 t_insert(p, to_char(0xC2, ch));
 107                         else
 108                                 t_insert(p, to_char(0xC3, ch - 64));
 109                         end
 110                 end
 111                 return t_concat(p);
 112         end
 113         local function parse(data)
 114                 local message = {}
 115                 -- COMPAT: %z in the pattern to work around jwchat bug (sends "charset=utf-8\0")
 116                 for k, v in s_gmatch(data, [[([%w%-]+)="?([^",%z]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
 117                         message[k] = v;
 118                 end
 119                 return message;
 120         end
 121
 122         if not self.nonce then
 123                 self.nonce = generate_uuid();
 124                 self.step = 0;
 125                 self.nonce_count = {};
 126         end
 127
 128         self.step = self.step + 1;
 129         if (self.step == 1) then
 130                 local challenge = serialize({   nonce = self.nonce,
 131                                                                                 qop = "auth",
 132                                                                                 charset = "utf-8",
 133                                                                                 algorithm = "md5-sess",
 134                                                                                 realm = self.realm});
 135                 return "challenge", challenge;
 136         elseif (self.step == 2) then
 137                 local response = parse(message);
 138                 -- check for replay attack
 139                 if response["nc"] then
 140                         if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
 141                 end
 142
 143                 -- check for username, it's REQUIRED by RFC 2831
 144                 local username = response["username"];
 145                 local _nodeprep = self.profile.nodeprep;
 146                 if username and _nodeprep ~= false then
 147                         username = (_nodeprep or nodeprep)(username); -- FIXME charset
 148                 end
 149                 if not username or username == "" then
 150                         return "failure", "malformed-request";
 151                 end
 152                 self.username = username;
 153
 154                 -- check for nonce, ...
 155                 if not response["nonce"] then
 156                         return "failure", "malformed-request";
 157                 else
 158                         -- check if it's the right nonce
 159                         if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
 160                 end
 161
 162                 if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
 163                 if not response["qop"] then response["qop"] = "auth" end
 164
 165                 if response["realm"] == nil or response["realm"] == "" then
 166                         response["realm"] = "";
 167                 elseif response["realm"] ~= self.realm then
 168                         return "failure", "not-authorized", "Incorrect realm value";
 169                 end
 170
 171                 local decoder;
 172                 if response["charset"] == nil then
 173                         decoder = utf8tolatin1ifpossible;
 174                 elseif response["charset"] ~= "utf-8" then
 175                         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.";
 176                 end
 177
 178                 local domain = "";
 179                 local protocol = "";
 180                 if response["digest-uri"] then
 181                         protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
 182                         if protocol == nil or domain == nil then return "failure", "malformed-request" end
 183                 else
 184                         return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
 185                 end
 186
 187                 --TODO maybe realm support
 188                 local Y, state;
 189                 if self.profile.plain then
 190                         local password, state = self.profile.plain(self, response["username"], self.realm)
 191                         if state == nil then return "failure", "not-authorized"
 192                         elseif state == false then return "failure", "account-disabled" end
 193                         Y = md5(response["username"]..":"..response["realm"]..":"..password);
 194                 elseif self.profile["digest-md5"] then
 195                         Y, state = self.profile["digest-md5"](self, response["username"], self.realm, response["realm"], response["charset"])
 196                         if state == nil then return "failure", "not-authorized"
 197                         elseif state == false then return "failure", "account-disabled" end
 198                 elseif self.profile["digest-md5-test"] then
 199                         -- TODO
 200                 end
 201                 --local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
 202                 --if Y == nil then return "failure", "not-authorized"
 203                 --elseif Y == false then return "failure", "account-disabled" end
 204                 local A1 = "";
 205                 if response.authzid then
 206                         if response.authzid == self.username or response.authzid == self.username.."@"..self.realm then
 207                                 -- COMPAT
 208                                 log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
 209                                 A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
 210                         else
 211                                 return "failure", "invalid-authzid";
 212                         end
 213                 else
 214                         A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
 215                 end
 216                 local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
 217
 218                 local HA1 = md5(A1, true);
 219                 local HA2 = md5(A2, true);
 220
 221                 local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
 222                 local response_value = md5(KD, true);
 223
 224                 if response_value == response["response"] then
 225                         -- calculate rspauth
 226                         A2 = ":"..protocol.."/"..domain;
 227
 228                         HA1 = md5(A1, true);
 229                         HA2 = md5(A2, true);
 230
 231                         KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
 232                         local rspauth = md5(KD, true);
 233                         self.authenticated = true;
 234                         --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
 235                         return "challenge", serialize({rspauth = rspauth});
 236                 else
 237                         return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
 238                 end
 239         elseif self.step == 3 then
 240                 if self.authenticated ~= nil then return "success"
 241                 else return "failure", "malformed-request" end
 242         end
 243 end
 244
 245 local function init(registerMechanism)
 246         registerMechanism("DIGEST-MD5", {"plain"}, digest);
 247 end
 248
 249 return {
 250         init = init;
 251 }