Merge pull request #1155 from matrix-org/erikj/pluggable_pwd_auth

Implement pluggable password auth

1 files changed, 368 insertions, 0 deletions

diff --git a/synapse/util/ldap_auth_provider.py b/synapse/util/ldap_auth_provider.py
new file mode 100644
index 0000000000..f852e9b037
--- /dev/null
+++ b/synapse/util/ldap_auth_provider.py
@@ -0,0 +1,368 @@
+
+from twisted.internet import defer
+
+from synapse.config._base import ConfigError
+from synapse.types import UserID
+
+import ldap3
+import ldap3.core.exceptions
+
+import logging
+
+try:
+    import ldap3
+    import ldap3.core.exceptions
+except ImportError:
+    ldap3 = None
+    pass
+
+
+logger = logging.getLogger(__name__)
+
+
+class LDAPMode(object):
+    SIMPLE = "simple",
+    SEARCH = "search",
+
+    LIST = (SIMPLE, SEARCH)
+
+
+class LdapAuthProvider(object):
+    __version__ = "0.1"
+
+    def __init__(self, config, account_handler):
+        self.account_handler = account_handler
+
+        if not ldap3:
+            raise RuntimeError(
+                'Missing ldap3 library. This is required for LDAP Authentication.'
+            )
+
+        self.ldap_mode = config.mode
+        self.ldap_uri = config.uri
+        self.ldap_start_tls = config.start_tls
+        self.ldap_base = config.base
+        self.ldap_attributes = config.attributes
+        if self.ldap_mode == LDAPMode.SEARCH:
+            self.ldap_bind_dn = config.bind_dn
+            self.ldap_bind_password = config.bind_password
+            self.ldap_filter = config.filter
+
+    @defer.inlineCallbacks
+    def check_password(self, user_id, password):
+        """ Attempt to authenticate a user against an LDAP Server
+            and register an account if none exists.
+
+            Returns:
+                True if authentication against LDAP was successful
+        """
+        localpart = UserID.from_string(user_id).localpart
+
+        try:
+            server = ldap3.Server(self.ldap_uri)
+            logger.debug(
+                "Attempting LDAP connection with %s",
+                self.ldap_uri
+            )
+
+            if self.ldap_mode == LDAPMode.SIMPLE:
+                result, conn = self._ldap_simple_bind(
+                    server=server, localpart=localpart, password=password
+                )
+                logger.debug(
+                    'LDAP authentication method simple bind returned: %s (conn: %s)',
+                    result,
+                    conn
+                )
+                if not result:
+                    defer.returnValue(False)
+            elif self.ldap_mode == LDAPMode.SEARCH:
+                result, conn = self._ldap_authenticated_search(
+                    server=server, localpart=localpart, password=password
+                )
+                logger.debug(
+                    'LDAP auth method authenticated search returned: %s (conn: %s)',
+                    result,
+                    conn
+                )
+                if not result:
+                    defer.returnValue(False)
+            else:
+                raise RuntimeError(
+                    'Invalid LDAP mode specified: {mode}'.format(
+                        mode=self.ldap_mode
+                    )
+                )
+
+            try:
+                logger.info(
+                    "User authenticated against LDAP server: %s",
+                    conn
+                )
+            except NameError:
+                logger.warn(
+                    "Authentication method yielded no LDAP connection, aborting!"
+                )
+                defer.returnValue(False)
+
+            # check if user with user_id exists
+            if (yield self.account_handler.check_user_exists(user_id)):
+                # exists, authentication complete
+                conn.unbind()
+                defer.returnValue(True)
+
+            else:
+                # does not exist, fetch metadata for account creation from
+                # existing ldap connection
+                query = "({prop}={value})".format(
+                    prop=self.ldap_attributes['uid'],
+                    value=localpart
+                )
+
+                if self.ldap_mode == LDAPMode.SEARCH and self.ldap_filter:
+                    query = "(&{filter}{user_filter})".format(
+                        filter=query,
+                        user_filter=self.ldap_filter
+                    )
+                logger.debug(
+                    "ldap registration filter: %s",
+                    query
+                )
+
+                conn.search(
+                    search_base=self.ldap_base,
+                    search_filter=query,
+                    attributes=[
+                        self.ldap_attributes['name'],
+                        self.ldap_attributes['mail']
+                    ]
+                )
+
+                if len(conn.response) == 1:
+                    attrs = conn.response[0]['attributes']
+                    mail = attrs[self.ldap_attributes['mail']][0]
+                    name = attrs[self.ldap_attributes['name']][0]
+
+                    # create account
+                    user_id, access_token = (
+                        yield self.account_handler.register(localpart=localpart)
+                    )
+
+                    # TODO: bind email, set displayname with data from ldap directory
+
+                    logger.info(
+                        "Registration based on LDAP data was successful: %d: %s (%s, %)",
+                        user_id,
+                        localpart,
+                        name,
+                        mail
+                    )
+
+                    defer.returnValue(True)
+                else:
+                    if len(conn.response) == 0:
+                        logger.warn("LDAP registration failed, no result.")
+                    else:
+                        logger.warn(
+                            "LDAP registration failed, too many results (%s)",
+                            len(conn.response)
+                        )
+
+                    defer.returnValue(False)
+
+            defer.returnValue(False)
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during ldap authentication: %s", e)
+            defer.returnValue(False)
+
+    @staticmethod
+    def parse_config(config):
+        class _LdapConfig(object):
+            pass
+
+        ldap_config = _LdapConfig()
+
+        ldap_config.enabled = config.get("enabled", False)
+
+        ldap_config.mode = LDAPMode.SIMPLE
+
+        # verify config sanity
+        _require_keys(config, [
+            "uri",
+            "base",
+            "attributes",
+        ])
+
+        ldap_config.uri = config["uri"]
+        ldap_config.start_tls = config.get("start_tls", False)
+        ldap_config.base = config["base"]
+        ldap_config.attributes = config["attributes"]
+
+        if "bind_dn" in config:
+            ldap_config.mode = LDAPMode.SEARCH
+            _require_keys(config, [
+                "bind_dn",
+                "bind_password",
+            ])
+
+            ldap_config.bind_dn = config["bind_dn"]
+            ldap_config.bind_password = config["bind_password"]
+            ldap_config.filter = config.get("filter", None)
+
+        # verify attribute lookup
+        _require_keys(config['attributes'], [
+            "uid",
+            "name",
+            "mail",
+        ])
+
+        return ldap_config
+
+    def _ldap_simple_bind(self, server, localpart, password):
+        """ Attempt a simple bind with the credentials
+            given by the user against the LDAP server.
+
+            Returns True, LDAP3Connection
+                if the bind was successful
+            Returns False, None
+                if an error occured
+        """
+
+        try:
+            # bind with the the local users ldap credentials
+            bind_dn = "{prop}={value},{base}".format(
+                prop=self.ldap_attributes['uid'],
+                value=localpart,
+                base=self.ldap_base
+            )
+            conn = ldap3.Connection(server, bind_dn, password)
+            logger.debug(
+                "Established LDAP connection in simple bind mode: %s",
+                conn
+            )
+
+            if self.ldap_start_tls:
+                conn.start_tls()
+                logger.debug(
+                    "Upgraded LDAP connection in simple bind mode through StartTLS: %s",
+                    conn
+                )
+
+            if conn.bind():
+                # GOOD: bind okay
+                logger.debug("LDAP Bind successful in simple bind mode.")
+                return True, conn
+
+            # BAD: bind failed
+            logger.info(
+                "Binding against LDAP failed for '%s' failed: %s",
+                localpart, conn.result['description']
+            )
+            conn.unbind()
+            return False, None
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during LDAP authentication: %s", e)
+            return False, None
+
+    def _ldap_authenticated_search(self, server, localpart, password):
+        """ Attempt to login with the preconfigured bind_dn
+            and then continue searching and filtering within
+            the base_dn
+
+            Returns (True, LDAP3Connection)
+                if a single matching DN within the base was found
+                that matched the filter expression, and with which
+                a successful bind was achieved
+
+                The LDAP3Connection returned is the instance that was used to
+                verify the password not the one using the configured bind_dn.
+            Returns (False, None)
+                if an error occured
+        """
+
+        try:
+            conn = ldap3.Connection(
+                server,
+                self.ldap_bind_dn,
+                self.ldap_bind_password
+            )
+            logger.debug(
+                "Established LDAP connection in search mode: %s",
+                conn
+            )
+
+            if self.ldap_start_tls:
+                conn.start_tls()
+                logger.debug(
+                    "Upgraded LDAP connection in search mode through StartTLS: %s",
+                    conn
+                )
+
+            if not conn.bind():
+                logger.warn(
+                    "Binding against LDAP with `bind_dn` failed: %s",
+                    conn.result['description']
+                )
+                conn.unbind()
+                return False, None
+
+            # construct search_filter like (uid=localpart)
+            query = "({prop}={value})".format(
+                prop=self.ldap_attributes['uid'],
+                value=localpart
+            )
+            if self.ldap_filter:
+                # combine with the AND expression
+                query = "(&{query}{filter})".format(
+                    query=query,
+                    filter=self.ldap_filter
+                )
+            logger.debug(
+                "LDAP search filter: %s",
+                query
+            )
+            conn.search(
+                search_base=self.ldap_base,
+                search_filter=query
+            )
+
+            if len(conn.response) == 1:
+                # GOOD: found exactly one result
+                user_dn = conn.response[0]['dn']
+                logger.debug('LDAP search found dn: %s', user_dn)
+
+                # unbind and simple bind with user_dn to verify the password
+                # Note: do not use rebind(), for some reason it did not verify
+                #       the password for me!
+                conn.unbind()
+                return self._ldap_simple_bind(server, localpart, password)
+            else:
+                # BAD: found 0 or > 1 results, abort!
+                if len(conn.response) == 0:
+                    logger.info(
+                        "LDAP search returned no results for '%s'",
+                        localpart
+                    )
+                else:
+                    logger.info(
+                        "LDAP search returned too many (%s) results for '%s'",
+                        len(conn.response), localpart
+                    )
+                conn.unbind()
+                return False, None
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during LDAP authentication: %s", e)
+            return False, None
+
+
+def _require_keys(config, required):
+    missing = [key for key in required if key not in config]
+    if missing:
+        raise ConfigError(
+            "LDAP enabled but missing required config values: {}".format(
+                ", ".join(missing)
+            )
+        )