2 -- Copyright (C) 2008-2010 Tobias Markmann
4 -- All rights reserved.
6 -- Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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.
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.
14 local s_match = string.match;
17 local tostring = tostring;
18 local base64 = require "util.encodings".base64;
19 local hmac_sha1 = require "util.hashes".hmac_sha1;
20 local sha1 = require "util.hashes".sha1;
21 local Hi = require "util.hashes".scram_Hi_sha1;
22 local generate_uuid = require "util.uuid".generate;
23 local saslprep = require "util.encodings".stringprep.saslprep;
24 local nodeprep = require "util.encodings".stringprep.nodeprep;
25 local log = require "util.logger".init("sasl");
26 local t_concat = table.concat;
27 local char = string.char;
28 local byte = string.byte;
32 --=========================
33 --SASL SCRAM-SHA-1 according to RFC 5802
36 Supported Authentication Backends
39 -- MECH being a standard hash name (like those at IANA's hash registry) with '-' replaced with '_'
40 function(username, realm)
41 return stored_key, server_key, iteration_count, salt, state;
44 Supported Channel Binding Backends
46 'tls-unique' according to RFC 5929
49 local default_i = 4096
51 local function bp( b )
54 result = result.."\\"..b:byte(i)
59 local xor_map = {0;1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;1;0;3;2;5;4;7;6;9;8;11;10;13;12;15;14;2;3;0;1;6;7;4;5;10;11;8;9;14;15;12;13;3;2;1;0;7;6;5;4;11;10;9;8;15;14;13;12;4;5;6;7;0;1;2;3;12;13;14;15;8;9;10;11;5;4;7;6;1;0;3;2;13;12;15;14;9;8;11;10;6;7;4;5;2;3;0;1;14;15;12;13;10;11;8;9;7;6;5;4;3;2;1;0;15;14;13;12;11;10;9;8;8;9;10;11;12;13;14;15;0;1;2;3;4;5;6;7;9;8;11;10;13;12;15;14;1;0;3;2;5;4;7;6;10;11;8;9;14;15;12;13;2;3;0;1;6;7;4;5;11;10;9;8;15;14;13;12;3;2;1;0;7;6;5;4;12;13;14;15;8;9;10;11;4;5;6;7;0;1;2;3;13;12;15;14;9;8;11;10;5;4;7;6;1;0;3;2;14;15;12;13;10;11;8;9;6;7;4;5;2;3;0;1;15;14;13;12;11;10;9;8;7;6;5;4;3;2;1;0;};
62 local function binaryXOR( a, b )
64 local x, y = byte(a, i), byte(b, i);
65 local lowx, lowy = x % 16, y % 16;
66 local hix, hiy = (x - lowx) / 16, (y - lowy) / 16;
67 local lowr, hir = xor_map[lowx * 16 + lowy + 1], xor_map[hix * 16 + hiy + 1];
68 local r = hir * 16 + lowr;
71 return t_concat(result);
74 local function validate_username(username, _nodeprep)
75 -- check for forbidden char sequences
76 for eq in username:gmatch("=(.?.?)") do
77 if eq ~= "2C" and eq ~= "3D" then
82 -- replace =2C with , and =3D with =
83 username = username:gsub("=2C", ",");
84 username = username:gsub("=3D", "=");
87 username = saslprep(username);
89 if username and _nodeprep ~= false then
90 username = (_nodeprep or nodeprep)(username);
93 return username and #username>0 and username;
96 local function hashprep(hashname)
97 return hashname:lower():gsub("-", "_");
100 function getAuthenticationDatabaseSHA1(password, salt, iteration_count)
101 if type(password) ~= "string" or type(salt) ~= "string" or type(iteration_count) ~= "number" then
102 return false, "inappropriate argument types"
104 if iteration_count < 4096 then
105 log("warn", "Iteration count < 4096 which is the suggested minimum according to RFC 5802.")
107 local salted_password = Hi(password, salt, iteration_count);
108 local stored_key = sha1(hmac_sha1(salted_password, "Client Key"))
109 local server_key = hmac_sha1(salted_password, "Server Key");
110 return true, stored_key, server_key
113 local function scram_gen(hash_name, H_f, HMAC_f)
114 local function scram_hash(self, message)
115 if not self.state then self["state"] = {} end
116 local support_channel_binding = false;
117 if self.profile.cb then support_channel_binding = true; end
119 if type(message) ~= "string" or #message == 0 then return "failure", "malformed-request" end
120 if not self.state.name then
121 -- we are processing client_first_message
122 local client_first_message = message;
124 -- TODO: fail if authzid is provided, since we don't support them yet
125 self.state["client_first_message"] = client_first_message;
126 self.state["gs2_cbind_flag"], self.state["gs2_cbind_name"], self.state["authzid"], self.state["name"], self.state["clientnonce"]
127 = client_first_message:match("^(%a)=?([%a%-]*),(.*),n=(.*),r=([^,]*).*");
129 -- check for invalid gs2_flag_type start
130 local gs2_flag_type = string.sub(self.state.gs2_cbind_flag, 0, 1)
131 if gs2_flag_type ~= "y" and gs2_flag_type ~= "n" and gs2_flag_type ~= "p" then
132 return "failure", "malformed-request", "The GS2 header has to start with 'y', 'n', or 'p'."
135 if support_channel_binding then
136 if string.sub(self.state.gs2_cbind_flag, 0, 1) == "y" then
137 return "failure", "malformed-request";
140 -- check whether we support the proposed channel binding type
141 if not self.profile.cb[self.state.gs2_cbind_name] then
142 return "failure", "malformed-request", "Proposed channel binding type isn't supported.";
145 -- we don't support channelbinding,
146 if self.state.gs2_cbind_flag ~= "n" and self.state.gs2_cbind_flag ~= "y" then
147 return "failure", "malformed-request";
151 if not self.state.name or not self.state.clientnonce then
152 return "failure", "malformed-request", "Channel binding isn't support at this time.";
155 self.state.name = validate_username(self.state.name, self.profile.nodeprep);
156 if not self.state.name then
157 log("debug", "Username violates either SASLprep or contains forbidden character sequences.")
158 return "failure", "malformed-request", "Invalid username.";
161 self.state["servernonce"] = generate_uuid();
163 -- retreive credentials
164 if self.profile.plain then
165 local password, state = self.profile.plain(self, self.state.name, self.realm)
166 if state == nil then return "failure", "not-authorized"
167 elseif state == false then return "failure", "account-disabled" end
169 password = saslprep(password);
171 log("debug", "Password violates SASLprep.");
172 return "failure", "not-authorized", "Invalid password."
175 self.state.salt = generate_uuid();
176 self.state.iteration_count = default_i;
179 succ, self.state.stored_key, self.state.server_key = getAuthenticationDatabaseSHA1(password, self.state.salt, default_i, self.state.iteration_count);
181 log("error", "Generating authentication database failed. Reason: %s", self.state.stored_key);
182 return "failure", "temporary-auth-failure";
184 elseif self.profile["scram_"..hashprep(hash_name)] then
185 local stored_key, server_key, iteration_count, salt, state = self.profile["scram_"..hashprep(hash_name)](self, self.state.name, self.realm);
186 if state == nil then return "failure", "not-authorized"
187 elseif state == false then return "failure", "account-disabled" end
189 self.state.stored_key = stored_key;
190 self.state.server_key = server_key;
191 self.state.iteration_count = iteration_count;
192 self.state.salt = salt
195 local server_first_message = "r="..self.state.clientnonce..self.state.servernonce..",s="..base64.encode(self.state.salt)..",i="..self.state.iteration_count;
196 self.state["server_first_message"] = server_first_message;
197 return "challenge", server_first_message
199 -- we are processing client_final_message
200 local client_final_message = message;
202 self.state["channelbinding"], self.state["nonce"], self.state["proof"] = client_final_message:match("^c=(.*),r=(.*),.*p=(.*)");
204 if not self.state.proof or not self.state.nonce or not self.state.channelbinding then
205 return "failure", "malformed-request", "Missing an attribute(p, r or c) in SASL message.";
208 if self.state.gs2_cbind_name then
209 -- we support channelbinding, so check if the value is valid
210 local client_gs2_header = base64.decode(self.state.channelbinding)
211 local our_client_gs2_header = "p="..self.state.gs2_cbind_name..","..self.state["authzid"]..","..self.profile.cb[self.state.gs2_cbind_name](self);
213 if client_gs2_header ~= our_client_gs2_header then
214 return "failure", "malformed-request", "Invalid channel binding value.";
218 if self.state.nonce ~= self.state.clientnonce..self.state.servernonce then
219 return "failure", "malformed-request", "Wrong nonce in client-final-message.";
222 local ServerKey = self.state.server_key;
223 local StoredKey = self.state.stored_key;
225 local AuthMessage = "n=" .. s_match(self.state.client_first_message,"n=(.+)") .. "," .. self.state.server_first_message .. "," .. s_match(client_final_message, "(.+),p=.+")
226 local ClientSignature = HMAC_f(StoredKey, AuthMessage)
227 local ClientKey = binaryXOR(ClientSignature, base64.decode(self.state.proof))
228 local ServerSignature = HMAC_f(ServerKey, AuthMessage)
230 if StoredKey == H_f(ClientKey) then
231 local server_final_message = "v="..base64.encode(ServerSignature);
232 self["username"] = self.state.name;
233 return "success", server_final_message;
235 return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated.";
242 function init(registerMechanism)
243 local function registerSCRAMMechanism(hash_name, hash, hmac_hash)
244 registerMechanism("SCRAM-"..hash_name, {"plain", "scram_"..(hashprep(hash_name))}, scram_gen(hash_name:lower(), hash, hmac_hash));
246 -- register channel binding equivalent
247 registerMechanism("SCRAM-"..hash_name.."-PLUS", {"plain", "scram_"..(hashprep(hash_name))}, scram_gen(hash_name:lower(), hash, hmac_hash), {"tls-unique"});
250 registerSCRAMMechanism("SHA-1", sha1, hmac_sha1);