diff options
Diffstat (limited to 'server/src/leap/soledad/server/auth.py')
| -rw-r--r-- | server/src/leap/soledad/server/auth.py | 529 |
1 files changed, 151 insertions, 378 deletions
diff --git a/server/src/leap/soledad/server/auth.py b/server/src/leap/soledad/server/auth.py index b0764569..b5744fe9 100644 --- a/server/src/leap/soledad/server/auth.py +++ b/server/src/leap/soledad/server/auth.py @@ -15,383 +15,156 @@ # You should have received a copy of the GNU General Public License # along with this program. If not, see <http://www.gnu.org/licenses/>. """ -Authentication facilities for Soledad Server. +Twisted http token auth. """ -import httplib -import json - -from abc import ABCMeta, abstractmethod -from routes.mapper import Mapper - -from leap.soledad.common.log import getLogger -from leap.soledad.common.l2db import DBNAME_CONSTRAINTS, errors as u1db_errors -from leap.soledad.common import SHARED_DB_NAME -from leap.soledad.common import USER_DB_PREFIX - - -logger = getLogger(__name__) - - -class URLToAuthorization(object): - """ - Verify if actions can be performed by a user. - """ - - HTTP_METHOD_GET = 'GET' - HTTP_METHOD_PUT = 'PUT' - HTTP_METHOD_DELETE = 'DELETE' - HTTP_METHOD_POST = 'POST' - - def __init__(self, uuid): - """ - Initialize the mapper. - - The C{uuid} is used to create the rules that will either allow or - disallow the user to perform specific actions. - - @param uuid: The user uuid. - @type uuid: str - @param user_db_prefix: The string prefix of users' databases. - @type user_db_prefix: str - """ - self._map = Mapper(controller_scan=None) - self._user_db_name = "%s%s" % (USER_DB_PREFIX, uuid) - self._uuid = uuid - self._register_auth_info() - - def is_authorized(self, environ): - """ - Return whether an HTTP request that produced the CGI C{environ} - corresponds to an authorized action. - - @param environ: Dictionary containing CGI variables. - @type environ: dict - - @return: Whether the action is authorized or not. - @rtype: bool - """ - return self._map.match(environ=environ) is not None - - def _register(self, pattern, http_methods): - """ - Register a C{pattern} in the mapper as valid for C{http_methods}. - - @param pattern: The URL pattern that corresponds to the user action. - @type pattern: str - @param http_methods: A list of authorized HTTP methods. - @type http_methods: list of str - """ - self._map.connect( - None, pattern, http_methods=http_methods, - conditions=dict(method=http_methods), - requirements={'dbname': DBNAME_CONSTRAINTS}) - - def _register_auth_info(self): - """ - Register the authorization info in the mapper using C{SHARED_DB_NAME} - as the user's database name. - - This method sets up the following authorization rules: - - URL path | Authorized actions - -------------------------------------------------- - / | GET - /shared-db | GET - /shared-db/docs | - - /shared-db/doc/{any_id} | GET, PUT, DELETE - /shared-db/sync-from/{source} | - - /user-db | GET, PUT, DELETE - /user-db/docs | - - /user-db/doc/{id} | - - /user-db/sync-from/{source} | GET, PUT, POST - """ - # auth info for global resource - self._register('/', [self.HTTP_METHOD_GET]) - # auth info for shared-db database resource - self._register( - '/%s' % SHARED_DB_NAME, - [self.HTTP_METHOD_GET]) - # auth info for shared-db doc resource - self._register( - '/%s/doc/{id:.*}' % SHARED_DB_NAME, - [self.HTTP_METHOD_GET, self.HTTP_METHOD_PUT, - self.HTTP_METHOD_DELETE]) - # auth info for user-db database resource - self._register( - '/%s' % self._user_db_name, - [self.HTTP_METHOD_GET, self.HTTP_METHOD_PUT, - self.HTTP_METHOD_DELETE]) - # auth info for user-db sync resource - self._register( - '/%s/sync-from/{source_replica_uid}' % self._user_db_name, - [self.HTTP_METHOD_GET, self.HTTP_METHOD_PUT, - self.HTTP_METHOD_POST]) - # generate the regular expressions - self._map.create_regs() - - -class SoledadAuthMiddleware(object): - """ - Soledad Authentication WSGI middleware. - - This class must be extended to implement specific authentication methods - (see SoledadTokenAuthMiddleware below). - - It expects an HTTP_AUTHORIZATION header containing the concatenation of - the following strings: - - 1. The authentication scheme. It will be verified by the - _verify_authentication_scheme() method. - - 2. A space character. - - 3. The base64 encoded string of the concatenation of the user uuid with - the authentication data, separated by a collon, like this: - - base64("<uuid>:<auth_data>") - - After authentication check, the class performs an authorization check to - verify whether the user is authorized to perform the requested action. - - On client-side, 2 methods must be implemented so the soledad client knows - how to send authentication headers to server: - - * set_<method>_credentials: store authentication credentials in the - class. - - * _sign_request: format and include custom authentication data in - the HTTP_AUTHORIZATION header. - - See leap.soledad.auth and u1db.remote.http_client.HTTPClient to understand - how to do it. - """ - - __metaclass__ = ABCMeta - - HTTP_AUTH_KEY = "HTTP_AUTHORIZATION" - PATH_INFO_KEY = "PATH_INFO" - - CONTENT_TYPE_JSON = ('content-type', 'application/json') - - def __init__(self, app): - """ - Initialize the Soledad Authentication Middleware. - - @param app: The application to run on successfull authentication. - @type app: u1db.remote.http_app.HTTPApp - @param prefix: Auth app path prefix. - @type prefix: str - """ - self._app = app - - def _error(self, start_response, status, description, message=None): - """ - Send a JSON serialized error to WSGI client. - - @param start_response: Callable of the form start_response(status, - response_headers, exc_info=None). - @type start_response: callable - @param status: Status string of the form "999 Message here" - @type status: str - @param response_headers: A list of (header_name, header_value) tuples - describing the HTTP response header. - @type response_headers: list - @param description: The error description. - @type description: str - @param message: The error message. - @type message: str - - @return: List with JSON serialized error message. - @rtype list - """ - start_response("%d %s" % (status, httplib.responses[status]), - [self.CONTENT_TYPE_JSON]) - err = {"error": description} - if message: - err['message'] = message - return [json.dumps(err)] - - def _unauthorized_error(self, start_response, message): - """ - Send a unauth error. - - @param message: The error message. - @type message: str - @param start_response: Callable of the form start_response(status, - response_headers, exc_info=None). - @type start_response: callable - - @return: List with JSON serialized error message. - @rtype list - """ - return self._error( - start_response, - 401, - "unauthorized", - message) - - def __call__(self, environ, start_response): - """ - Handle a WSGI call to the authentication application. - - @param environ: Dictionary containing CGI variables. - @type environ: dict - @param start_response: Callable of the form start_response(status, - response_headers, exc_info=None). - @type start_response: callable - - @return: Target application results if authentication succeeds, an - error message otherwise. - @rtype: list - """ - # check for authentication header - auth = environ.get(self.HTTP_AUTH_KEY) - if not auth: - return self._unauthorized_error( - start_response, "Missing authentication header.") - - # get authentication data - scheme, encoded = auth.split(None, 1) - uuid, auth_data = encoded.decode('base64').split(':', 1) - if not self._verify_authentication_scheme(scheme): - return self._unauthorized_error( - start_response, "Wrong authentication scheme") - - # verify if user is athenticated - try: - if not self._verify_authentication_data(uuid, auth_data): - return self._unauthorized_error( - start_response, - self._get_auth_error_string()) - except u1db_errors.Unauthorized as e: - return self._error( - start_response, - 401, - e.wire_description) - - # verify if user is authorized to perform action - if not self._verify_authorization(environ, uuid): - return self._unauthorized_error( - start_response, - "Unauthorized action.") - - # move on to the real Soledad app - del environ[self.HTTP_AUTH_KEY] - return self._app(environ, start_response) - - @abstractmethod - def _verify_authentication_scheme(self, scheme): - """ - Verify if authentication scheme is valid. - - @param scheme: Auth scheme extracted from the HTTP_AUTHORIZATION - header. - @type scheme: str - - @return: Whether the authentitcation scheme is valid. - """ - return None - - @abstractmethod - def _verify_authentication_data(self, uuid, auth_data): - """ - Verify valid authenticatiion for this request. - - @param uuid: The user's uuid. - @type uuid: str - @param auth_data: Authentication data. - @type auth_data: str - - @return: Whether the token is valid for authenticating the request. - @rtype: bool - - @raise Unauthorized: Raised when C{auth_data} is not enough to - authenticate C{uuid}. - """ - return None - - def _verify_authorization(self, environ, uuid): - """ - Verify if the user is authorized to perform the requested action over - the requested database. - - @param environ: Dictionary containing CGI variables. - @type environ: dict - @param uuid: The user's uuid. - @type uuid: str - - @return: Whether the user is authorize to perform the requested action - over the requested db. - @rtype: bool - """ - return URLToAuthorization(uuid).is_authorized(environ) - - @abstractmethod - def _get_auth_error_string(self): - """ - Return an error string specific for each kind of authentication method. - - @return: The error string. - """ - return None - - -class SoledadTokenAuthMiddleware(SoledadAuthMiddleware): - """ - Token based authentication. - """ - - TOKEN_AUTH_ERROR_STRING = "Incorrect address or token." - - def _get_state(self): - return self._app.state - - def _set_state(self, state): - self._app.state = state - - state = property(_get_state, _set_state) - - def _verify_authentication_scheme(self, scheme): - """ - Verify if authentication scheme is valid. - - @param scheme: Auth scheme extracted from the HTTP_AUTHORIZATION - header. - @type scheme: str - - @return: Whether the authentitcation scheme is valid. - """ - if scheme.lower() != 'token': - return False - return True - - def _verify_authentication_data(self, uuid, auth_data): - """ - Extract token from C{auth_data} and proceed with verification of - C{uuid} authentication. - - @param uuid: The user UID. - @type uuid: str - @param auth_data: Authentication data (i.e. the token). - @type auth_data: str - - @return: Whether the token is valid for authenticating the request. - @rtype: bool - - @raise Unauthorized: Raised when C{auth_data} is not enough to - authenticate C{uuid}. - """ - token = auth_data # we expect a cleartext token at this point +import binascii +import time + +from hashlib import sha512 +from zope.interface import implementer + +from twisted.cred import error +from twisted.cred.checkers import ICredentialsChecker +from twisted.cred.credentials import IUsernamePassword +from twisted.cred.credentials import IAnonymous +from twisted.cred.credentials import Anonymous +from twisted.cred.credentials import UsernamePassword +from twisted.cred.portal import IRealm +from twisted.cred.portal import Portal +from twisted.internet import defer +from twisted.logger import Logger +from twisted.web.iweb import ICredentialFactory +from twisted.web.resource import IResource + +from leap.soledad.common.couch import couch_server + +from ._resource import SoledadResource, SoledadAnonResource +from ._config import get_config + + +log = Logger() + + +@implementer(IRealm) +class SoledadRealm(object): + + def __init__(self, sync_pool, conf=None): + assert sync_pool is not None + if conf is None: + conf = get_config() + blobs = conf['blobs'] + self.anon_resource = SoledadAnonResource( + enable_blobs=blobs) + self.auth_resource = SoledadResource( + enable_blobs=blobs, + sync_pool=sync_pool) + + def requestAvatar(self, avatarId, mind, *interfaces): + + # Anonymous access + if IAnonymous.providedBy(avatarId): + return (IResource, self.anon_resource, + lambda: None) + + # Authenticated access + else: + if IResource in interfaces: + return (IResource, self.auth_resource, + lambda: None) + raise NotImplementedError() + + +@implementer(ICredentialsChecker) +class TokenChecker(object): + + credentialInterfaces = [IUsernamePassword, IAnonymous] + + TOKENS_DB_PREFIX = "tokens_" + TOKENS_DB_EXPIRE = 30 * 24 * 3600 # 30 days in seconds + TOKENS_TYPE_KEY = "type" + TOKENS_TYPE_DEF = "Token" + TOKENS_USER_ID_KEY = "user_id" + + def __init__(self): + self._couch_url = get_config().get('couch_url') + + def _get_server(self): + return couch_server(self._couch_url) + + def _tokens_dbname(self): + # the tokens db rotates every 30 days, and the current db name is + # "tokens_NNN", where NNN is the number of seconds since epoch + # divide dby the rotate period in seconds. When rotating, old and + # new tokens db coexist during a certain window of time and valid + # tokens are replicated from the old db to the new one. See: + # https://leap.se/code/issues/6785 + dbname = self.TOKENS_DB_PREFIX + \ + str(int(time.time() / self.TOKENS_DB_EXPIRE)) + return dbname + + def _tokens_db(self): + dbname = self._tokens_dbname() + + # TODO -- leaking abstraction here: this module shouldn't need + # to known anything about the context manager. hide that in the couch + # module + with self._get_server() as server: + db = server[dbname] + return db + + def requestAvatarId(self, credentials): + if IAnonymous.providedBy(credentials): + return defer.succeed(Anonymous()) + + uuid = credentials.username + token = credentials.password + + # lookup key is a hash of the token to prevent timing attacks. + # TODO cache the tokens already! + + db = self._tokens_db() + token = db.get(sha512(token).hexdigest()) + if token is None: + return defer.fail(error.UnauthorizedLogin()) + + # TODO -- use cryptography constant time builtin comparison. + # we compare uuid hashes to avoid possible timing attacks that + # might exploit python's builtin comparison operator behaviour, + # which fails immediatelly when non-matching bytes are found. + couch_uuid_hash = sha512(token[self.TOKENS_USER_ID_KEY]).digest() + req_uuid_hash = sha512(uuid).digest() + if token[self.TOKENS_TYPE_KEY] != self.TOKENS_TYPE_DEF \ + or couch_uuid_hash != req_uuid_hash: + return defer.fail(error.UnauthorizedLogin()) + + return defer.succeed(uuid) + + +@implementer(ICredentialFactory) +class TokenCredentialFactory(object): + + scheme = 'token' + + def getChallenge(self, request): + return {} + + def decode(self, response, request): try: - return self.state.verify_token(uuid, token) - except Exception as e: - logger.error(e) - return False - - def _get_auth_error_string(self): - """ - Get the error string for token auth. - - @return: The error string. - """ - return self.TOKEN_AUTH_ERROR_STRING + creds = binascii.a2b_base64(response + b'===') + except binascii.Error: + raise error.LoginFailed('Invalid credentials') + + creds = creds.split(b':', 1) + if len(creds) == 2: + return UsernamePassword(*creds) + else: + raise error.LoginFailed('Invalid credentials') + + +def portalFactory(sync_pool): + realm = SoledadRealm(sync_pool=sync_pool) + checker = TokenChecker() + return Portal(realm, [checker]) + + +credentialFactory = TokenCredentialFactory() |