vcs: Only allow 'pull' actions on shadow repositories.

We are exposing the shadow repositories of pull requests to allow easy CI integration
or users to access the pull request shadow repo for investigating on it. But we don't
want someone/something to push changes to a shadow repository.

rhodecode/lib/middleware/simplevcs.py

@@ -1,479 +1,488 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2014-2016  RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 """
 SimpleVCS middleware for handling protocol request (push/clone etc.)
 It's implemented with basic auth function
 """
 
 import os
 import logging
 import importlib
 import re
 from functools import wraps
 
 from paste.httpheaders import REMOTE_USER, AUTH_TYPE
 from webob.exc import (
     HTTPNotFound, HTTPForbidden, HTTPNotAcceptable, HTTPInternalServerError)
 
 import rhodecode
 from rhodecode.authentication.base import authenticate, VCS_TYPE
 from rhodecode.lib.auth import AuthUser, HasPermissionAnyMiddleware
 from rhodecode.lib.base import BasicAuth, get_ip_addr, vcs_operation_context
 from rhodecode.lib.exceptions import (
     HTTPLockedRC, HTTPRequirementError, UserCreationError,
     NotAllowedToCreateUserError)
 from rhodecode.lib.hooks_daemon import prepare_callback_daemon
 from rhodecode.lib.middleware import appenlight
 from rhodecode.lib.middleware.utils import scm_app
 from rhodecode.lib.utils import (
     is_valid_repo, get_rhodecode_realm, get_rhodecode_base_path)
 from rhodecode.lib.utils2 import safe_str, fix_PATH, str2bool
 from rhodecode.lib.vcs.conf import settings as vcs_settings
 from rhodecode.lib.vcs.backends import base
 from rhodecode.model import meta
 from rhodecode.model.db import User, Repository
 from rhodecode.model.scm import ScmModel
 
 
 log = logging.getLogger(__name__)
 
 
 def initialize_generator(factory):
     """
     Initializes the returned generator by draining its first element.
 
     This can be used to give a generator an initializer, which is the code
     up to the first yield statement. This decorator enforces that the first
     produced element has the value ``"__init__"`` to make its special
     purpose very explicit in the using code.
     """
 
     @wraps(factory)
     def wrapper(*args, **kwargs):
         gen = factory(*args, **kwargs)
         try:
             init = gen.next()
         except StopIteration:
             raise ValueError('Generator must yield at least one element.')
         if init != "__init__":
             raise ValueError('First yielded element must be "__init__".')
         return gen
     return wrapper
 
 
 class SimpleVCS(object):
     """Common functionality for SCM HTTP handlers."""
 
     SCM = 'unknown'
 
     acl_repo_name = None
     url_repo_name = None
     vcs_repo_name = None
 
     def __init__(self, application, config, registry):
         self.registry = registry
         self.application = application
         self.config = config
         # re-populated by specialized middleware
         self.repo_vcs_config = base.Config()
 
         # base path of repo locations
         self.basepath = get_rhodecode_base_path()
         # authenticate this VCS request using authfunc
         auth_ret_code_detection = \
             str2bool(self.config.get('auth_ret_code_detection', False))
         self.authenticate = BasicAuth(
             '', authenticate, registry, config.get('auth_ret_code'),
             auth_ret_code_detection)
         self.ip_addr = '0.0.0.0'
 
     def set_repo_names(self, environ):
         """
         This will populate the attributes acl_repo_name, url_repo_name and
         vcs_repo_name on the current instance.
         """
         # TODO: martinb: Move to class or module scope.
         pr_regex = re.compile(
             '(?P<base_name>(?:[\w-]+)(?:/[\w-]+)*)/'
             '(?P<repo_name>[\w-]+)'
             '/pull-request/(?P<pr_id>\d+)/repository')
 
         self.url_repo_name = self._get_repository_name(environ)
         match = pr_regex.match(self.url_repo_name)
 
         if match:
             match_dict = match.groupdict()
             self.acl_repo_name = '{base_name}/{repo_name}'.format(**match_dict)
             self.vcs_repo_name = '{base_name}/.__shadow_{repo_name}_pr-{pr_id}'.format(
                 **match_dict)
             self.pr_id = match_dict['pr_id']
         else:
             self.acl_repo_name = self.url_repo_name
             self.vcs_repo_name = self.url_repo_name
             self.pr_id = None
 
     @property
     def repo_name(self):
         # TODO: johbo: Remove, switch to correct repo name attribute
         return self.acl_repo_name
 
     @property
     def scm_app(self):
         custom_implementation = self.config.get('vcs.scm_app_implementation')
         if custom_implementation and custom_implementation != 'pyro4':
             log.info(
                 "Using custom implementation of scm_app: %s",
                 custom_implementation)
             scm_app_impl = importlib.import_module(custom_implementation)
         else:
             scm_app_impl = scm_app
         return scm_app_impl
 
     def _get_by_id(self, repo_name):
         """
         Gets a special pattern _<ID> from clone url and tries to replace it
         with a repository_name for support of _<ID> non changeable urls
         """
 
         data = repo_name.split('/')
         if len(data) >= 2:
             from rhodecode.model.repo import RepoModel
             by_id_match = RepoModel().get_repo_by_id(repo_name)
             if by_id_match:
                 data[1] = by_id_match.repo_name
 
         return safe_str('/'.join(data))
 
     def _invalidate_cache(self, repo_name):
         """
         Set's cache for this repository for invalidation on next access
 
         :param repo_name: full repo name, also a cache key
         """
         ScmModel().mark_for_invalidation(repo_name)
 
     def is_valid_and_existing_repo(self, repo_name, base_path, scm_type):
         db_repo = Repository.get_by_repo_name(repo_name)
         if not db_repo:
             log.debug('Repository `%s` not found inside the database.',
                       repo_name)
             return False
 
         if db_repo.repo_type != scm_type:
             log.warning(
                 'Repository `%s` have incorrect scm_type, expected %s got %s',
                 repo_name, db_repo.repo_type, scm_type)
             return False
 
         return is_valid_repo(repo_name, base_path, expect_scm=scm_type)
 
     def valid_and_active_user(self, user):
         """
         Checks if that user is not empty, and if it's actually object it checks
         if he's active.
 
         :param user: user object or None
         :return: boolean
         """
         if user is None:
             return False
 
         elif user.active:
             return True
 
         return False
 
     def _check_permission(self, action, user, repo_name, ip_addr=None):
         """
         Checks permissions using action (push/pull) user and repository
         name
 
         :param action: push or pull action
         :param user: user instance
         :param repo_name: repository name
         """
         # check IP
         inherit = user.inherit_default_permissions
         ip_allowed = AuthUser.check_ip_allowed(user.user_id, ip_addr,
                                                inherit_from_default=inherit)
         if ip_allowed:
             log.info('Access for IP:%s allowed', ip_addr)
         else:
             return False
 
         if action == 'push':
             if not HasPermissionAnyMiddleware('repository.write',
                                               'repository.admin')(user,
                                                                   repo_name):
                 return False
 
         else:
             # any other action need at least read permission
             if not HasPermissionAnyMiddleware('repository.read',
                                               'repository.write',
                                               'repository.admin')(user,
                                                                   repo_name):
                 return False
 
         return True
 
     def _check_ssl(self, environ, start_response):
         """
         Checks the SSL check flag and returns False if SSL is not present
         and required True otherwise
         """
         org_proto = environ['wsgi._org_proto']
         # check if we have SSL required  ! if not it's a bad request !
         require_ssl = str2bool(self.repo_vcs_config.get('web', 'push_ssl'))
         if require_ssl and org_proto == 'http':
             log.debug('proto is %s and SSL is required BAD REQUEST !',
                       org_proto)
             return False
         return True
 
     def __call__(self, environ, start_response):
         try:
             return self._handle_request(environ, start_response)
         except Exception:
             log.exception("Exception while handling request")
             appenlight.track_exception(environ)
             return HTTPInternalServerError()(environ, start_response)
         finally:
             meta.Session.remove()
 
     def _handle_request(self, environ, start_response):
 
         if not self._check_ssl(environ, start_response):
             reason = ('SSL required, while RhodeCode was unable '
                       'to detect this as SSL request')
             log.debug('User not allowed to proceed, %s', reason)
             return HTTPNotAcceptable(reason)(environ, start_response)
 
         if not self.repo_name:
             log.warning('Repository name is empty: %s', self.repo_name)
             # failed to get repo name, we fail now
             return HTTPNotFound()(environ, start_response)
         log.debug('Extracted repo name is %s', self.repo_name)
 
         ip_addr = get_ip_addr(environ)
         username = None
 
         # skip passing error to error controller
         environ['pylons.status_code_redirect'] = True
 
         # ======================================================================
         # GET ACTION PULL or PUSH
         # ======================================================================
         action = self._get_action(environ)
 
         # ======================================================================
+        # Check if this is a request to a shadow repository of a pull request.
+        # In this case only pull action is allowed.
+        # ======================================================================
+        if self.pr_id is not None and action != 'pull':
+            reason = 'Only pull action is allowed for shadow repositories.'
+            log.debug('User not allowed to proceed, %s', reason)
+            return HTTPNotAcceptable(reason)(environ, start_response)
+
+        # ======================================================================
         # CHECK ANONYMOUS PERMISSION
         # ======================================================================
         if action in ['pull', 'push']:
             anonymous_user = User.get_default_user()
             username = anonymous_user.username
             if anonymous_user.active:
                 # ONLY check permissions if the user is activated
                 anonymous_perm = self._check_permission(
                     action, anonymous_user, self.repo_name, ip_addr)
             else:
                 anonymous_perm = False
 
             if not anonymous_user.active or not anonymous_perm:
                 if not anonymous_user.active:
                     log.debug('Anonymous access is disabled, running '
                               'authentication')
 
                 if not anonymous_perm:
                     log.debug('Not enough credentials to access this '
                               'repository as anonymous user')
 
                 username = None
                 # ==============================================================
                 # DEFAULT PERM FAILED OR ANONYMOUS ACCESS IS DISABLED SO WE
                 # NEED TO AUTHENTICATE AND ASK FOR AUTH USER PERMISSIONS
                 # ==============================================================
 
                 # try to auth based on environ, container auth methods
                 log.debug('Running PRE-AUTH for container based authentication')
                 pre_auth = authenticate(
                     '', '', environ, VCS_TYPE, registry=self.registry)
                 if pre_auth and pre_auth.get('username'):
                     username = pre_auth['username']
                 log.debug('PRE-AUTH got %s as username', username)
 
                 # If not authenticated by the container, running basic auth
                 if not username:
                     self.authenticate.realm = get_rhodecode_realm()
 
                     try:
                         result = self.authenticate(environ)
                     except (UserCreationError, NotAllowedToCreateUserError) as e:
                         log.error(e)
                         reason = safe_str(e)
                         return HTTPNotAcceptable(reason)(environ, start_response)
 
                     if isinstance(result, str):
                         AUTH_TYPE.update(environ, 'basic')
                         REMOTE_USER.update(environ, result)
                         username = result
                     else:
                         return result.wsgi_application(environ, start_response)
 
                 # ==============================================================
                 # CHECK PERMISSIONS FOR THIS REQUEST USING GIVEN USERNAME
                 # ==============================================================
                 user = User.get_by_username(username)
                 if not self.valid_and_active_user(user):
                     return HTTPForbidden()(environ, start_response)
                 username = user.username
                 user.update_lastactivity()
                 meta.Session().commit()
 
                 # check user attributes for password change flag
                 user_obj = user
                 if user_obj and user_obj.username != User.DEFAULT_USER and \
                         user_obj.user_data.get('force_password_change'):
                     reason = 'password change required'
                     log.debug('User not allowed to authenticate, %s', reason)
                     return HTTPNotAcceptable(reason)(environ, start_response)
 
                 # check permissions for this repository
                 perm = self._check_permission(
                     action, user, self.repo_name, ip_addr)
                 if not perm:
                     return HTTPForbidden()(environ, start_response)
 
         # extras are injected into UI object and later available
         # in hooks executed by rhodecode
         check_locking = _should_check_locking(environ.get('QUERY_STRING'))
         extras = vcs_operation_context(
             environ, repo_name=self.repo_name, username=username,
             action=action, scm=self.SCM,
             check_locking=check_locking)
 
         # ======================================================================
         # REQUEST HANDLING
         # ======================================================================
         str_repo_name = safe_str(self.repo_name)
         repo_path = os.path.join(
             safe_str(self.basepath), safe_str(self.vcs_repo_name))
         log.debug('Repository path is %s', repo_path)
 
         fix_PATH()
 
         log.info(
             '%s action on %s repo "%s" by "%s" from %s',
             action, self.SCM, str_repo_name, safe_str(username), ip_addr)
 
         return self._generate_vcs_response(
             environ, start_response, repo_path, self.url_repo_name, extras, action)
 
     @initialize_generator
     def _generate_vcs_response(
             self, environ, start_response, repo_path, repo_name, extras,
             action):
         """
         Returns a generator for the response content.
 
         This method is implemented as a generator, so that it can trigger
         the cache validation after all content sent back to the client. It
         also handles the locking exceptions which will be triggered when
         the first chunk is produced by the underlying WSGI application.
         """
         callback_daemon, extras = self._prepare_callback_daemon(extras)
         config = self._create_config(extras, self.acl_repo_name)
         log.debug('HOOKS extras is %s', extras)
         app = self._create_wsgi_app(repo_path, repo_name, config)
 
         try:
             with callback_daemon:
                 try:
                     response = app(environ, start_response)
                 finally:
                     # This statement works together with the decorator
                     # "initialize_generator" above. The decorator ensures that
                     # we hit the first yield statement before the generator is
                     # returned back to the WSGI server. This is needed to
                     # ensure that the call to "app" above triggers the
                     # needed callback to "start_response" before the
                     # generator is actually used.
                     yield "__init__"
 
                 for chunk in response:
                     yield chunk
         except Exception as exc:
             # TODO: johbo: Improve "translating" back the exception.
             if getattr(exc, '_vcs_kind', None) == 'repo_locked':
                 exc = HTTPLockedRC(*exc.args)
                 _code = rhodecode.CONFIG.get('lock_ret_code')
                 log.debug('Repository LOCKED ret code %s!', (_code,))
             elif getattr(exc, '_vcs_kind', None) == 'requirement':
                 log.debug(
                     'Repository requires features unknown to this Mercurial')
                 exc = HTTPRequirementError(*exc.args)
             else:
                 raise
 
             for chunk in exc(environ, start_response):
                 yield chunk
         finally:
             # invalidate cache on push
             try:
                 if action == 'push':
                     self._invalidate_cache(repo_name)
             finally:
                 meta.Session.remove()
 
     def _get_repository_name(self, environ):
         """Get repository name out of the environmnent
 
         :param environ: WSGI environment
         """
         raise NotImplementedError()
 
     def _get_action(self, environ):
         """Map request commands into a pull or push command.
 
         :param environ: WSGI environment
         """
         raise NotImplementedError()
 
     def _create_wsgi_app(self, repo_path, repo_name, config):
         """Return the WSGI app that will finally handle the request."""
         raise NotImplementedError()
 
     def _create_config(self, extras, repo_name):
         """Create a Pyro safe config representation."""
         raise NotImplementedError()
 
     def _prepare_callback_daemon(self, extras):
         return prepare_callback_daemon(
             extras, protocol=vcs_settings.HOOKS_PROTOCOL,
             use_direct_calls=vcs_settings.HOOKS_DIRECT_CALLS)
 
 
 def _should_check_locking(query_string):
     # this is kind of hacky, but due to how mercurial handles client-server
     # server see all operation on commit; bookmarks, phases and
     # obsolescence marker in different transaction, we don't want to check
     # locking on those
     return query_string not in ['cmd=listkeys']