Merge pull request #4 from nitmir/dev

Add more optional password check to the mysql auth backend

README.rst

@@ -199,8 +199,19 @@ Mysql backend settings. Only usefull if you are using the mysql authentication b
   The username must be in field ``username``, the password in ``password``,
   additional fields are used as the user attributes.
   The default is ``"SELECT user AS usersame, pass AS password, users.* FROM users WHERE user = %s"``
-* ``CAS_SQL_PASSWORD_CHECK``: The method used to check the user password. Must be
+* ``CAS_SQL_PASSWORD_CHECK``: The method used to check the user password. Must be one of the following:
-  ``"crypt"`` or ``"plain``". The default is ``"crypt"``.
+
+    * ``"crypt"`` (see <https://en.wikipedia.org/wiki/Crypt_(C)>), the password in the database
+      should begin this $
+    * ``"ldap"`` (see https://tools.ietf.org/id/draft-stroeder-hashed-userpassword-values-01.html)
+      the password in the database must begin with one of {MD5}, {SMD5}, {SHA}, {SSHA}, {SHA256},
+      {SSHA256}, {SHA384}, {SSHA384}, {SHA512}, {SSHA512}, {CRYPT}.
+    * ``"hex_HASH_NAME"`` with ``HASH_NAME`` in md5, sha1, sha224, sha256, sha384, sha512.
+      The hashed password in the database is compare to the hexadecimal digest of the clear
+      password hashed with the corresponding algorithm.
+    * ``"plain"``, the password in the database must be in clear.
+
+  The default is ``"crypt"``.
 
 
 Test backend settings. Only usefull if you are using the test authentication backend:

cas_server/auth.py

@@ -15,7 +15,7 @@ from django.contrib.auth import get_user_model
 try:  # pragma: no cover
     import MySQLdb
     import MySQLdb.cursors
-    import crypt
+    from utils import check_password
 except ImportError:
     MySQLdb = None
 
@@ -90,17 +90,12 @@ class MysqlAuthUser(AuthUser):  # pragma: no cover
     def test_password(self, password):
         """test `password` agains the user"""
         if self.user:
-            if settings.CAS_SQL_PASSWORD_CHECK == "plain":
+            check_password(
-                return password == self.user["password"]
+                settings.CAS_SQL_PASSWORD_CHECK,
-            elif settings.CAS_SQL_PASSWORD_CHECK == "crypt":
+                password,
-                if self.user["password"].startswith('$'):
+                self.user["password"],
-                    salt = '$'.join(self.user["password"].split('$', 3)[:-1])
+                settings.CAS_SQL_DBCHARSET
-                    return crypt.crypt(password, salt) == self.user["password"]
+            )
-                else:
-                    return crypt.crypt(
-                        password,
-                        self.user["password"][:2]
-                    ) == self.user["password"]
         else:
             return False
 

cas_server/tests.py

@@ -3,6 +3,7 @@ from .default_settings import settings
 from django.test import TestCase
 from django.test import Client
 
+import six
 from lxml import etree
 
 from cas_server import models
@@ -59,6 +60,68 @@ def get_pgt():
     return params
 
 
+class CheckPasswordCase(TestCase):
+    """Tests for the utils function `utils.check_password`"""
+
+    def setUp(self):
+        """Generate random bytes string that will be used ass passwords"""
+        self.password1 = utils.gen_saml_id()
+        self.password2 = utils.gen_saml_id()
+        if not isinstance(self.password1, bytes):
+            self.password1 = self.password1.encode("utf8")
+            self.password2 = self.password2.encode("utf8")
+
+    def test_setup(self):
+        """check that generated password are bytes"""
+        self.assertIsInstance(self.password1, bytes)
+        self.assertIsInstance(self.password2, bytes)
+
+    def test_plain(self):
+        """test the plain auth method"""
+        self.assertTrue(utils.check_password("plain", self.password1, self.password1, "utf8"))
+        self.assertFalse(utils.check_password("plain", self.password1, self.password2, "utf8"))
+
+    def test_crypt(self):
+        """test the crypt auth method"""
+        if six.PY3:
+            hashed_password1 = utils.crypt.crypt(
+                self.password1.decode("utf8"),
+                "$6$UVVAQvrMyXMF3FF3"
+            ).encode("utf8")
+        else:
+            hashed_password1 = utils.crypt.crypt(self.password1, "$6$UVVAQvrMyXMF3FF3")
+
+        self.assertTrue(utils.check_password("crypt", self.password1, hashed_password1, "utf8"))
+        self.assertFalse(utils.check_password("crypt", self.password2, hashed_password1, "utf8"))
+
+    def test_ldap_ssha(self):
+        """test the ldap auth method with a {SSHA} scheme"""
+        salt = b"UVVAQvrMyXMF3FF3"
+        hashed_password1 = utils.LdapHashUserPassword.hash(b'{SSHA}', self.password1, salt, "utf8")
+
+        self.assertIsInstance(hashed_password1, bytes)
+        self.assertTrue(utils.check_password("ldap", self.password1, hashed_password1, "utf8"))
+        self.assertFalse(utils.check_password("ldap", self.password2, hashed_password1, "utf8"))
+
+    def test_hex_md5(self):
+        """test the hex_md5 auth method"""
+        hashed_password1 = utils.hashlib.md5(self.password1).hexdigest()
+
+        self.assertTrue(utils.check_password("hex_md5", self.password1, hashed_password1, "utf8"))
+        self.assertFalse(utils.check_password("hex_md5", self.password2, hashed_password1, "utf8"))
+
+    def test_hox_sha512(self):
+        """test the hex_sha512 auth method"""
+        hashed_password1 = utils.hashlib.sha512(self.password1).hexdigest()
+
+        self.assertTrue(
+            utils.check_password("hex_sha512", self.password1, hashed_password1, "utf8")
+        )
+        self.assertFalse(
+            utils.check_password("hex_sha512", self.password2, hashed_password1, "utf8")
+        )
+
+
 class LoginTestCase(TestCase):
 
     def setUp(self):

cas_server/utils.py

@@ -19,6 +19,10 @@ from django.contrib import messages
 import random
 import string
 import json
+import hashlib
+import crypt
+import base64
+import six
 from threading import Thread
 from importlib import import_module
 from six.moves import BaseHTTPServer
@@ -172,3 +176,177 @@ class PGTUrlHandler(BaseHTTPServer.BaseHTTPRequestHandler):
         httpd_thread.daemon = True
         httpd_thread.start()
         return (httpd_thread, host, port)
+
+
+class LdapHashUserPassword(object):
+    """Please see https://tools.ietf.org/id/draft-stroeder-hashed-userpassword-values-01.html"""
+
+    schemes_salt = {b"{SMD5}", b"{SSHA}", b"{SSHA256}", b"{SSHA384}", b"{SSHA512}", b"{CRYPT}"}
+    schemes_nosalt = {b"{MD5}", b"{SHA}", b"{SHA256}", b"{SHA384}", b"{SHA512}"}
+
+    _schemes_to_hash = {
+        b"{SMD5}": hashlib.md5,
+        b"{MD5}": hashlib.md5,
+        b"{SSHA}": hashlib.sha1,
+        b"{SHA}": hashlib.sha1,
+        b"{SSHA256}": hashlib.sha256,
+        b"{SHA256}": hashlib.sha256,
+        b"{SSHA384}": hashlib.sha384,
+        b"{SHA384}": hashlib.sha384,
+        b"{SSHA512}": hashlib.sha512,
+        b"{SHA512}": hashlib.sha512
+    }
+
+    _schemes_to_len = {
+        b"{SMD5}": 16,
+        b"{SSHA}": 20,
+        b"{SSHA256}": 32,
+        b"{SSHA384}": 48,
+        b"{SSHA512}": 64,
+    }
+
+    class BadScheme(ValueError):
+        """Error raised then the hash scheme is not in schemes_salt + schemes_nosalt"""
+        pass
+
+    class BadHash(ValueError):
+        """Error raised then the hash is too short"""
+        pass
+
+    class BadSalt(ValueError):
+        """Error raised then with the scheme {CRYPT} the salt is invalid"""
+        pass
+
+    @classmethod
+    def _raise_bad_scheme(cls, scheme, valid, msg):
+        """
+            Raise BadScheme error for `scheme`, possible valid scheme are
+            in `valid`, the error message is `msg`
+        """
+        valid_schemes = [s.decode() for s in valid]
+        valid_schemes.sort()
+        raise cls.BadScheme(msg % (scheme, u", ".join(valid_schemes)))
+
+    @classmethod
+    def _test_scheme(cls, scheme):
+        """Test if a scheme is valide or raise BadScheme"""
+        if scheme not in cls.schemes_salt and scheme not in cls.schemes_nosalt:
+            cls._raise_bad_scheme(
+                scheme,
+                cls.schemes_salt | cls.schemes_nosalt,
+                "The scheme %r is not valid. Valide schemes are %s."
+            )
+
+    @classmethod
+    def _test_scheme_salt(cls, scheme):
+        """Test if the scheme need a salt or raise BadScheme"""
+        if scheme not in cls.schemes_salt:
+            cls._raise_bad_scheme(
+                scheme,
+                cls.schemes_salt,
+                "The scheme %r is only valid without a salt. Valide schemes with salt are %s."
+            )
+
+    @classmethod
+    def _test_scheme_nosalt(cls, scheme):
+        """Test if the scheme need no salt or raise BadScheme"""
+        if scheme not in cls.schemes_nosalt:
+            cls._raise_bad_scheme(
+                scheme,
+                cls.schemes_nosalt,
+                "The scheme %r is only valid with a salt. Valide schemes without salt are %s."
+            )
+
+    @classmethod
+    def hash(cls, scheme, password, salt=None, charset="utf8"):
+        """
+           Hash `password` with `scheme` using `salt`.
+           This three variable beeing encoded in `charset`.
+        """
+        scheme = scheme.upper()
+        cls._test_scheme(scheme)
+        if salt is None or salt == b"":
+            salt = b""
+            cls._test_scheme_nosalt(scheme)
+        elif salt is not None:
+            cls._test_scheme_salt(scheme)
+        try:
+            return scheme + base64.b64encode(
+                cls._schemes_to_hash[scheme](password + salt).digest() + salt
+            )
+        except KeyError:
+            if six.PY3:
+                password = password.decode(charset)
+                salt = salt.decode(charset)
+            hashed_password = crypt.crypt(password, salt)
+            if hashed_password is None:
+                raise cls.BadSalt("System crypt implementation do not support the salt %r" % salt)
+            if six.PY3:
+                hashed_password = hashed_password.encode(charset)
+            return scheme + hashed_password
+
+    @classmethod
+    def get_scheme(cls, hashed_passord):
+        """Return the scheme of `hashed_passord` or raise BadHash"""
+        if not hashed_passord[0] == b'{'[0] or b'}' not in hashed_passord:
+            raise cls.BadHash("%r should start with the scheme enclosed with { }" % hashed_passord)
+        scheme = hashed_passord.split(b'}', 1)[0]
+        scheme = scheme.upper() + b"}"
+        return scheme
+
+    @classmethod
+    def get_salt(cls, hashed_passord):
+        """Return the salt of `hashed_passord` possibly empty"""
+        scheme = cls.get_scheme(hashed_passord)
+        cls._test_scheme(scheme)
+        if scheme in cls.schemes_nosalt:
+            return b""
+        elif scheme == b'{CRYPT}':
+            return b'$'.join(hashed_passord.split(b'$', 3)[:-1])
+        else:
+            hashed_passord = base64.b64decode(hashed_passord[len(scheme):])
+            if len(hashed_passord) < cls._schemes_to_len[scheme]:
+                raise cls.BadHash("Hash too short for the scheme %s" % scheme)
+            return hashed_passord[cls._schemes_to_len[scheme]:]
+
+
+def check_password(method, password, hashed_password, charset):
+    """
+        Check that `password` match `hashed_password` using `method`,
+        assuming the encoding is `charset`.
+    """
+    if not isinstance(password, six.binary_type):
+        password = password.encode(charset)
+    if not isinstance(hashed_password, six.binary_type):
+        hashed_password = hashed_password.encode(charset)
+    if method == "plain":
+        return password == hashed_password
+    elif method == "crypt":
+        if hashed_password.startswith(b'$'):
+            salt = b'$'.join(hashed_password.split(b'$', 3)[:-1])
+        elif hashed_password.startswith(b'_'):
+            salt = hashed_password[:9]
+        else:
+            salt = hashed_password[:2]
+        if six.PY3:
+            password = password.decode(charset)
+            salt = salt.decode(charset)
+            hashed_password = hashed_password.decode(charset)
+        crypted_password = crypt.crypt(password, salt)
+        if crypted_password is None:
+            raise ValueError("System crypt implementation do not support the salt %r" % salt)
+        return crypted_password == hashed_password
+    elif method == "ldap":
+        scheme = LdapHashUserPassword.get_scheme(hashed_password)
+        salt = LdapHashUserPassword.get_salt(hashed_password)
+        return LdapHashUserPassword.hash(scheme, password, salt, charset=charset) == hashed_password
+    elif (
+       method.startswith("hex_") and
+       method[4:] in {"md5", "sha1", "sha224", "sha256", "sha384", "sha512"}
+    ):
+        return getattr(
+            hashlib,
+            method[4:]
+        )(password).hexdigest().encode("ascii") == hashed_password.lower()
+    else:
+        raise ValueError("Unknown password method check %r" % method)