-- sasl.lua v0.4
--- Copyright (C) 2008-2009 Tobias Markmann
+-- Copyright (C) 2008-2010 Tobias Markmann
--
-- All rights reserved.
--
-- 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.
-local md5 = require "util.hashes".md5;
-local log = require "util.logger".init("sasl");
-local tostring = tostring;
-local st = require "util.stanza";
-local generate_uuid = require "util.uuid".generate;
-local t_insert, t_concat = table.insert, table.concat;
-local to_byte, to_char = string.byte, string.char;
-local to_unicode = require "util.encodings".idna.to_unicode;
-local s_match = string.match;
-local gmatch = string.gmatch
-local string = string
-local math = require "math"
+local pairs, ipairs = pairs, ipairs;
+local t_insert = table.insert;
local type = type
-local error = error
+local setmetatable = setmetatable;
+local assert = assert;
+local require = require;
local print = print
module "sasl"
--- Credentials handler:
--- Arguments: ("PLAIN", user, host, password)
--- Returns: true (success) | false (fail) | nil (user unknown)
-local function new_plain(realm, credentials_handler)
- local object = { mechanism = "PLAIN", realm = realm, credentials_handler = credentials_handler}
- function object.feed(self, message)
- if message == "" or message == nil then return "failure", "malformed-request" end
- local response = message
- local authorization = s_match(response, "([^&%z]+)")
- local authentication = s_match(response, "%z([^&%z]+)%z")
- local password = s_match(response, "%z[^&%z]+%z([^&%z]+)")
+--[[
+Authentication Backend Prototypes:
- if authentication == nil or password == nil then return "failure", "malformed-request" end
- self.username = authentication
- local auth_success = self.credentials_handler("PLAIN", self.username, self.realm, password)
+state = false : disabled
+state = true : enabled
+state = nil : non-existant
- if auth_success then
- return "success"
- elseif auth_success == nil then
- return "failure", "account-disabled"
- else
- return "failure", "not-authorized"
- end
- end
- return object
-end
-
--- credentials_handler:
--- Arguments: (mechanism, node, domain, realm, decoder)
--- Returns: Password encoding, (plaintext) password
--- implementing RFC 2831
-local function new_digest_md5(realm, credentials_handler)
- --TODO complete support for authzid
-
- local function serialize(message)
- local data = ""
+Channel Binding:
- if type(message) ~= "table" then error("serialize needs an argument of type table.") end
+To enable support of channel binding in some mechanisms you need to provide appropriate callbacks in a table
+at profile.cb.
- -- testing all possible values
- if message["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
- if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
- if message["charset"] then data = data..[[charset=]]..message.charset.."," end
- if message["algorithm"] then data = data..[[algorithm=]]..message.algorithm.."," end
- if message["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
- if message["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
- data = data:gsub(",$", "")
- return data
+Example:
+ profile.cb["tls-unique"] = function(self)
+ return self.user
end
- local function utf8tolatin1ifpossible(passwd)
- local i = 1;
- while i <= #passwd do
- local passwd_i = to_byte(passwd:sub(i, i));
- if passwd_i > 0x7F then
- if passwd_i < 0xC0 or passwd_i > 0xC3 then
- return passwd;
- end
- i = i + 1;
- passwd_i = to_byte(passwd:sub(i, i));
- if passwd_i < 0x80 or passwd_i > 0xBF then
- return passwd;
- end
- end
- i = i + 1;
+]]
+
+local method = {};
+method.__index = method;
+local mechanisms = {};
+local backend_mechanism = {};
+local mechanism_channelbindings = {};
+
+-- register a new SASL mechanims
+local function registerMechanism(name, backends, f, cb_backends)
+ assert(type(name) == "string", "Parameter name MUST be a string.");
+ assert(type(backends) == "string" or type(backends) == "table", "Parameter backends MUST be either a string or a table.");
+ assert(type(f) == "function", "Parameter f MUST be a function.");
+ if cb_backends then assert(type(cb_backends) == "table"); end
+ mechanisms[name] = f
+ if cb_backends then
+ mechanism_channelbindings[name] = {};
+ for _, cb_name in ipairs(cb_backends) do
+ mechanism_channelbindings[name][cb_name] = true;
end
-
- local p = {};
- local j = 0;
- i = 1;
- while (i <= #passwd) do
- local passwd_i = to_byte(passwd:sub(i, i));
- if passwd_i > 0x7F then
- i = i + 1;
- local passwd_i_1 = to_byte(passwd:sub(i, i));
- t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
- else
- t_insert(p, to_char(passwd_i));
- end
- i = i + 1;
- end
- return t_concat(p);
end
- local function latin1toutf8(str)
- local p = {};
- for ch in gmatch(str, ".") do
- ch = to_byte(ch);
- if (ch < 0x80) then
- t_insert(p, to_char(ch));
- elseif (ch < 0xC0) then
- t_insert(p, to_char(0xC2, ch));
- else
- t_insert(p, to_char(0xC3, ch - 64));
- end
- end
- return t_concat(p);
+ for _, backend_name in ipairs(backends) do
+ if backend_mechanism[backend_name] == nil then backend_mechanism[backend_name] = {}; end
+ t_insert(backend_mechanism[backend_name], name);
end
- local function parse(data)
- message = {}
- for k, v in gmatch(data, [[([%w%-]+)="?([^",]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
- message[k] = v;
- end
- return message;
- end
-
- local object = { mechanism = "DIGEST-MD5", realm = realm, credentials_handler = credentials_handler};
-
- object.nonce = generate_uuid();
- object.step = 0;
- object.nonce_count = {};
-
- function object.feed(self, message)
- self.step = self.step + 1;
- if (self.step == 1) then
- local challenge = serialize({ nonce = object.nonce,
- qop = "auth",
- charset = "utf-8",
- algorithm = "md5-sess",
- realm = self.realm});
- return "challenge", challenge;
- elseif (self.step == 2) then
- local response = parse(message);
- -- check for replay attack
- if response["nc"] then
- if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
- end
-
- -- check for username, it's REQUIRED by RFC 2831
- if not response["username"] then
- return "failure", "malformed-request";
- end
- self["username"] = response["username"];
-
- -- check for nonce, ...
- if not response["nonce"] then
- return "failure", "malformed-request";
- else
- -- check if it's the right nonce
- if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
- end
-
- if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
- if not response["qop"] then response["qop"] = "auth" end
+end
- if response["realm"] == nil or response["realm"] == "" then
- response["realm"] = "";
- elseif response["realm"] ~= self.realm then
- return "failure", "not-authorized", "Incorrect realm value";
+-- create a new SASL object which can be used to authenticate clients
+function new(realm, profile)
+ local mechanisms = {};
+ for backend, f in pairs(profile) do
+ if backend_mechanism[backend] then
+ for _, mechanism in ipairs(backend_mechanism[backend]) do
+ mechanisms[mechanism] = true;
end
+ end
+ end
+ return setmetatable({ profile = profile, realm = realm, mechs = mechanisms }, method);
+end
- local decoder;
- if response["charset"] == nil then
- decoder = utf8tolatin1ifpossible;
- elseif response["charset"] ~= "utf-8" then
- 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.";
- end
+-- add a channel binding handler
+function method:add_cb_handler(name, f)
+ if type(self.profile.cb) ~= "table" then
+ self.profile.cb = {};
+ end
+ self.profile.cb[name] = f;
+ return self;
+end
- local domain = "";
- local protocol = "";
- if response["digest-uri"] then
- protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
- if protocol == nil or domain == nil then return "failure", "malformed-request" end
- else
- return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
- end
+-- get a fresh clone with the same realm and profile
+function method:clean_clone()
+ return new(self.realm, self.profile)
+end
- --TODO maybe realm support
- self.username = response["username"];
- local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], to_unicode(domain), response["realm"], decoder);
- if Y == nil then return "failure", "not-authorized"
- elseif Y == false then return "failure", "account-disabled" end
- local A1 = "";
- if response.authzid then
- if response.authzid == self.username.."@"..self.realm then
- -- COMPAT
- log("warn", "Client is violating XMPP RFC. See section 6.1 of RFC 3920.");
- A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
- else
- A1 = "?";
+-- get a list of possible SASL mechanims to use
+function method:mechanisms()
+ local current_mechs = {};
+ for mech, _ in pairs(self.mechs) do
+ if mechanism_channelbindings[mech] and self.profile.cb then
+ local ok = false;
+ for cb_name, _ in pairs(self.profile.cb) do
+ if mechanism_channelbindings[mech][cb_name] then
+ ok = true;
end
- else
- A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
end
- local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
-
- local HA1 = md5(A1, true);
- local HA2 = md5(A2, true);
-
- local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
- local response_value = md5(KD, true);
-
- if response_value == response["response"] then
- -- calculate rspauth
- A2 = ":"..protocol.."/"..domain;
-
- HA1 = md5(A1, true);
- HA2 = md5(A2, true);
-
- KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
- local rspauth = md5(KD, true);
- self.authenticated = true;
- return "challenge", serialize({rspauth = rspauth});
- else
- return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
- end
- elseif self.step == 3 then
- if self.authenticated ~= nil then return "success"
- else return "failure", "malformed-request" end
+ if ok == true then current_mechs[mech] = true; end
+ else
+ current_mechs[mech] = true;
end
end
- return object;
+ return current_mechs;
end
--- Credentials handler: Can be nil. If specified, should take the mechanism as
--- the only argument, and return true for OK, or false for not-OK (TODO)
-local function new_anonymous(realm, credentials_handler)
- local object = { mechanism = "ANONYMOUS", realm = realm, credentials_handler = credentials_handler}
- function object.feed(self, message)
- return "success"
- end
- object["username"] = generate_uuid()
- return object
+-- select a mechanism to use
+function method:select(mechanism)
+ if not self.selected and self.mechs[mechanism] then
+ self.selected = mechanism;
+ return true;
+ end
end
-
-function new(mechanism, realm, credentials_handler)
- local object
- if mechanism == "PLAIN" then object = new_plain(realm, credentials_handler)
- elseif mechanism == "DIGEST-MD5" then object = new_digest_md5(realm, credentials_handler)
- elseif mechanism == "ANONYMOUS" then object = new_anonymous(realm, credentials_handler)
- else
- log("debug", "Unsupported SASL mechanism: "..tostring(mechanism));
- return nil
- end
- return object
+-- feed new messages to process into the library
+function method:process(message)
+ --if message == "" or message == nil then return "failure", "malformed-request" end
+ return mechanisms[self.selected](self, message);
end
+-- load the mechanisms
+require "util.sasl.plain" .init(registerMechanism);
+require "util.sasl.digest-md5".init(registerMechanism);
+require "util.sasl.anonymous" .init(registerMechanism);
+require "util.sasl.scram" .init(registerMechanism);
+
return _M;
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