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Diffstat (limited to 'oslo_middleware/basic_auth.py')
-rw-r--r-- | oslo_middleware/basic_auth.py | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/oslo_middleware/basic_auth.py b/oslo_middleware/basic_auth.py new file mode 100644 index 0000000..2c9c901 --- /dev/null +++ b/oslo_middleware/basic_auth.py @@ -0,0 +1,203 @@ +# Copyright 2012 OpenStack Foundation +# All Rights Reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may +# not use this file except in compliance with the License. You may obtain +# a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +# License for the specific language governing permissions and limitations +# under the License. + +import base64 +import binascii +import logging + +import bcrypt +import webob + +from oslo_config import cfg +from oslo_middleware import base + +LOG = logging.getLogger(__name__) + +OPTS = [ + cfg.StrOpt('http_basic_auth_user_file', + default='/etc/htpasswd', + help="HTTP basic auth password file.") +] + +cfg.CONF.register_opts(OPTS, group='oslo_middleware') + + +class ConfigInvalid(Exception): + def __init__(self, error_msg): + super().__init__( + 'Invalid configuration file. %(error_msg)s') + + +class BasicAuthMiddleware(base.ConfigurableMiddleware): + """Middleware which performs HTTP basic authentication on requests""" + + def __init__(self, application, conf=None): + super().__init__(application, conf) + self.auth_file = cfg.CONF.oslo_middleware.http_basic_auth_user_file + validate_auth_file(self.auth_file) + + def format_exception(self, e): + result = {'error': {'message': str(e), 'code': 401}} + headers = [('Content-Type', 'application/json')] + return webob.Response(content_type='application/json', + status_code=401, + json_body=result, + headerlist=headers) + + @webob.dec.wsgify + def __call__(self, req): + try: + token = parse_header(req.environ) + username, password = parse_token(token) + req.environ.update(authenticate( + self.auth_file, username, password)) + return self.application + except Exception as e: + response = self.format_exception(e) + return self.process_response(response) + + +def authenticate(auth_file, username, password): + """Finds username and password match in Apache style user auth file + + The user auth file format is expected to comply with Apache + documentation[1] however the bcrypt password digest is the *only* + digest format supported. + + [1] https://httpd.apache.org/docs/current/misc/password_encryptions.html + + :param: auth_file: Path to user auth file + :param: username: Username to authenticate + :param: password: Password encoded as bytes + :returns: A dictionary of WSGI environment values to append to the request + :raises: HTTPUnauthorized, if no file entries match username/password + """ + + line_prefix = username + ':' + try: + with open(auth_file, 'r') as f: + for line in f: + entry = line.strip() + if entry and entry.startswith(line_prefix): + return auth_entry(entry, password) + except OSError as exc: + LOG.error('Problem reading auth file: %s', exc) + raise webob.exc.HTTPBadRequest( + detail='Problem reading auth file') + # reached end of file with no matches + LOG.info('User %s not found', username) + raise webob.exc.HTTPUnauthorized() + + +def auth_entry(entry, password): + """Compare a password with a single user auth file entry + + :param: entry: Line from auth user file to use for authentication + :param: password: Password encoded as bytes + :returns: A dictionary of WSGI environment values to append to the request + :raises: HTTPUnauthorized, if the entry doesn't match supplied password or + if the entry is crypted with a method other than bcrypt + """ + + username, crypted = parse_entry(entry) + if not bcrypt.checkpw(password, crypted): + LOG.info('Password for %s does not match', username) + raise webob.exc.HTTPUnauthorized() + return { + 'HTTP_X_USER': username, + 'HTTP_X_USER_NAME': username + } + + +def validate_auth_file(auth_file): + """Read the auth user file and validate its correctness + + :param: auth_file: Path to user auth file + :raises: ConfigInvalid on validation error + """ + + try: + with open(auth_file, 'r') as f: + for line in f: + entry = line.strip() + if entry and ':' in entry: + parse_entry(entry) + except OSError: + raise ConfigInvalid(error_msg='Problem reading auth user file') + + +def parse_entry(entry): + """Extrace the username and crypted password from a user auth file entry + + :param: entry: Line from auth user file to use for authentication + :returns: a tuple of username and crypted password + :raises: ConfigInvalid if the password is not in the supported bcrypt + format + """ + + username, crypted_str = entry.split(':', maxsplit=1) + crypted = crypted_str.encode('utf-8') + if crypted[:4] not in (b'$2y$', b'$2a$', b'$2b$'): + error_msg = ('Only bcrypt digested passwords are supported for ' + '%(username)s') % {'username': username} + raise webob.exc.HTTPBadRequest(detail=error_msg) + return username, crypted + + +def parse_token(token): + """Parse the token portion of the Authentication header value + + :param: token: Token value from basic authorization header + :returns: tuple of username, password + :raises: BadRequest, if username and password could not be parsed for any + reason + """ + + try: + if isinstance(token, str): + token = token.encode('utf-8') + auth_pair = base64.b64decode(token, validate=True) + (username, password) = auth_pair.split(b':', maxsplit=1) + return (username.decode('utf-8'), password) + except (TypeError, binascii.Error, ValueError) as exc: + LOG.info('Could not decode authorization token: %s', exc) + raise webob.exc.HTTPBadRequest(detail=( + 'Could not decode authorization token')) + + +def parse_header(env): + """Parse WSGI environment for Authorization header of type Basic + + :param: env: WSGI environment to get header from + :returns: Token portion of the header value + :raises: HTTPUnauthorized, if header is missing or if the type is not Basic + """ + + try: + auth_header = env.pop('HTTP_AUTHORIZATION') + except KeyError: + LOG.info('No authorization token received') + raise webob.exc.HTTPUnauthorized() + try: + auth_type, token = auth_header.strip().split(maxsplit=1) + except (ValueError, AttributeError) as exc: + LOG.info('Could not parse Authorization header: %s', exc) + raise webob.exc.HTTPBadRequest(detail=( + 'Could not parse Authorization header')) + if auth_type.lower() != 'basic': + error_msg = ('Unsupported authorization type "%s"') % auth_type + LOG.info(error_msg) + raise webob.exc.HTTPBadRequest(detail=error_msg) + return token |