373 lines
13 KiB
Python
373 lines
13 KiB
Python
import logging
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import functools
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from bson import ObjectId
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from flask import g
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from flask import abort
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from flask import current_app
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from werkzeug.exceptions import Forbidden
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CHECK_PERMISSIONS_IMPLEMENTED_FOR = {'projects', 'nodes'}
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log = logging.getLogger(__name__)
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def check_permissions(collection_name, resource, method, append_allowed_methods=False,
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check_node_type=None):
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"""Check user permissions to access a node. We look up node permissions from
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world to groups to users and match them with the computed user permissions.
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If there is not match, we raise 403.
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:param collection_name: name of the collection the resource comes from.
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:param resource: resource from MongoDB
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:type resource: dict
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:param method: name of the requested HTTP method
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:param append_allowed_methods: whether to return the list of allowed methods
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in the resource. Only valid when method='GET'.
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:param check_node_type: node type to check. Only valid when collection_name='projects'.
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:type check_node_type: str
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"""
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if not has_permissions(collection_name, resource, method, append_allowed_methods,
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check_node_type):
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abort(403)
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def compute_allowed_methods(collection_name, resource, check_node_type=None):
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"""Computes the HTTP methods that are allowed on a given resource.
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:param collection_name: name of the collection the resource comes from.
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:param resource: resource from MongoDB
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:type resource: dict
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:param check_node_type: node type to check. Only valid when collection_name='projects'.
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:type check_node_type: str
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:returns: Set of allowed methods
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:rtype: set
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"""
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# Check some input values.
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if collection_name not in CHECK_PERMISSIONS_IMPLEMENTED_FOR:
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raise ValueError('compute_allowed_methods only implemented for %s, not for %s',
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CHECK_PERMISSIONS_IMPLEMENTED_FOR, collection_name)
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if check_node_type is not None and collection_name != 'projects':
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raise ValueError('check_node_type parameter is only valid for checking projects.')
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computed_permissions = compute_aggr_permissions(collection_name, resource, check_node_type)
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if not computed_permissions:
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log.info('No permissions available to compute for resource %r',
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resource.get('node_type', resource))
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return set()
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# Accumulate allowed methods from the user, group and world level.
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allowed_methods = set()
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current_user = g.current_user
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if current_user:
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# If the user is authenticated, proceed to compare the group permissions
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for permission in computed_permissions.get('groups', ()):
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if permission['group'] in current_user['groups']:
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allowed_methods.update(permission['methods'])
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for permission in computed_permissions.get('users', ()):
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if current_user['user_id'] == permission['user']:
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allowed_methods.update(permission['methods'])
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# Check if the node is public or private. This must be set for non logged
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# in users to see the content. For most BI projects this is on by default,
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# while for private project this will not be set at all.
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if 'world' in computed_permissions:
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allowed_methods.update(computed_permissions['world'])
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return allowed_methods
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def has_permissions(collection_name, resource, method, append_allowed_methods=False,
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check_node_type=None):
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"""Check user permissions to access a node. We look up node permissions from
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world to groups to users and match them with the computed user permissions.
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:param collection_name: name of the collection the resource comes from.
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:param resource: resource from MongoDB
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:type resource: dict
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:param method: name of the requested HTTP method
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:param append_allowed_methods: whether to return the list of allowed methods
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in the resource. Only valid when method='GET'.
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:param check_node_type: node type to check. Only valid when collection_name='projects'.
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:type check_node_type: str
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:returns: True if the user has access, False otherwise.
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:rtype: bool
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"""
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# Check some input values.
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if append_allowed_methods and method != 'GET':
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raise ValueError("append_allowed_methods only allowed with 'GET' method")
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allowed_methods = compute_allowed_methods(collection_name, resource, check_node_type)
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permission_granted = method in allowed_methods
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if permission_granted:
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if append_allowed_methods:
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# TODO: rename this field _allowed_methods
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if check_node_type:
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node_type = next((node_type for node_type in resource['node_types']
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if node_type['name'] == check_node_type))
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assign_to = node_type
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else:
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assign_to = resource
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assign_to['allowed_methods'] = list(set(allowed_methods))
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return True
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else:
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log.debug('Permission denied, method %s not in allowed methods %s',
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method, allowed_methods)
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return False
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def compute_aggr_permissions(collection_name, resource, check_node_type):
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"""Returns a permissions dict."""
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# We always need the know the project.
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if collection_name == 'projects':
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project = resource
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if check_node_type is None:
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return project['permissions']
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node_type_name = check_node_type
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else:
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# Not a project, so it's a node.
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assert 'project' in resource
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assert 'node_type' in resource
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node_type_name = resource['node_type']
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if isinstance(resource['project'], dict):
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# embedded project
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project = resource['project']
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else:
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project_id = resource['project']
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project = _find_project_node_type(project_id, node_type_name)
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# Every node should have a project.
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if project is None:
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log.warning('Resource %s from "%s" refers to a project that does not exist.',
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resource['_id'], collection_name)
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raise Forbidden()
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project_permissions = project['permissions']
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# Find the node type from the project.
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node_type = next((node_type for node_type in project['node_types']
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if node_type['name'] == node_type_name), None)
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if node_type is None: # This node type is not known, so doesn't give permissions.
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node_type_permissions = {}
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else:
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node_type_permissions = node_type.get('permissions', {})
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# For projects or specific node types in projects, we're done now.
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if collection_name == 'projects':
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return merge_permissions(project_permissions, node_type_permissions)
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node_permissions = resource.get('permissions', {})
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return merge_permissions(project_permissions, node_type_permissions, node_permissions)
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def _find_project_node_type(project_id, node_type_name):
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"""Returns the project with just the one named node type."""
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# Cache result per request, as many nodes of the same project can be checked.
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cache = g.get('_find_project_node_type_cache')
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if cache is None:
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cache = g._find_project_node_type_cache = {}
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try:
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return cache[(project_id, node_type_name)]
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except KeyError:
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pass
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projects_collection = current_app.data.driver.db['projects']
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project = projects_collection.find_one(
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ObjectId(project_id),
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{'permissions': 1,
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'node_types': {'$elemMatch': {'name': node_type_name}},
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'node_types.name': 1,
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'node_types.permissions': 1})
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cache[(project_id, node_type_name)] = project
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return project
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def merge_permissions(*args):
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"""Merges all given permissions.
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:param args: list of {'user': ..., 'group': ..., 'world': ...} dicts.
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:returns: combined list of permissions.
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"""
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if not args:
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return {}
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if len(args) == 1:
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return args[0]
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effective = {}
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# When testing we want stable results, and not be dependent on PYTHONHASH values etc.
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if current_app.config['TESTING']:
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maybe_sorted = sorted
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else:
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def maybe_sorted(arg):
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return arg
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def merge(field_name):
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plural_name = field_name + 's'
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from0 = args[0].get(plural_name, [])
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from1 = args[1].get(plural_name, [])
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asdict0 = {permission[field_name]: permission['methods'] for permission in from0}
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asdict1 = {permission[field_name]: permission['methods'] for permission in from1}
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keys = set(asdict0.keys() + asdict1.keys())
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for key in maybe_sorted(keys):
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methods0 = asdict0.get(key, [])
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methods1 = asdict1.get(key, [])
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methods = maybe_sorted(set(methods0).union(set(methods1)))
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effective.setdefault(plural_name, []).append({field_name: key, u'methods': methods})
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merge(u'user')
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merge(u'group')
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# Gather permissions for world
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world0 = args[0].get('world', [])
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world1 = args[1].get('world', [])
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world_methods = set(world0).union(set(world1))
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if world_methods:
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effective[u'world'] = maybe_sorted(world_methods)
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# Recurse for longer merges
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if len(args) > 2:
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return merge_permissions(effective, *args[2:])
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return effective
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def require_login(require_roles=set(),
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require_all=False):
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"""Decorator that enforces users to authenticate.
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Optionally only allows access to users with a certain role.
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:param require_roles: set of roles.
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:param require_all:
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When False (the default): if the user's roles have a
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non-empty intersection with the given roles, access is granted.
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When True: require the user to have all given roles before access is
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granted.
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"""
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if not isinstance(require_roles, set):
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raise TypeError('require_roles param should be a set, but is a %r' % type(require_roles))
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if require_all and not require_roles:
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raise ValueError('require_login(require_all=True) cannot be used with empty require_roles.')
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def decorator(func):
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@functools.wraps(func)
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def wrapper(*args, **kwargs):
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if not user_matches_roles(require_roles, require_all):
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if g.current_user is None:
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# We don't need to log at a higher level, as this is very common.
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# Many browsers first try to see whether authentication is needed
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# at all, before sending the password.
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log.debug('Unauthenticated acces to %s attempted.', func)
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else:
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log.warning('User %s is authenticated, but does not have required roles %s to '
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'access %s', g.current_user['user_id'], require_roles, func)
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abort(403)
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return func(*args, **kwargs)
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return wrapper
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return decorator
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def ab_testing(require_roles=set(),
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require_all=False):
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"""Decorator that raises a 404 when the user doesn't match the roles..
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:param require_roles: set of roles.
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:param require_all:
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When False (the default): if the user's roles have a
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non-empty intersection with the given roles, access is granted.
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When True: require the user to have all given roles before access is
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granted.
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"""
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if not isinstance(require_roles, set):
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raise TypeError('require_roles param should be a set, but is a %r' % type(require_roles))
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if require_all and not require_roles:
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raise ValueError('require_login(require_all=True) cannot be used with empty require_roles.')
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def decorator(func):
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@functools.wraps(func)
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def wrapper(*args, **kwargs):
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if not user_matches_roles(require_roles, require_all):
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abort(404)
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return func(*args, **kwargs)
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return wrapper
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return decorator
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def user_has_role(role, user=None):
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"""Returns True iff the user is logged in and has the given role."""
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if user is None:
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user = g.get('current_user')
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if user is None:
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return False
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roles = user.get('roles') or ()
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return role in roles
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def user_matches_roles(require_roles=set(),
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require_all=False):
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"""Returns True iff the user's roles matches the query.
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:param require_roles: set of roles.
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:param require_all:
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When False (the default): if the user's roles have a
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non-empty intersection with the given roles, returns True.
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When True: require the user to have all given roles before
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returning True.
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"""
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if not isinstance(require_roles, set):
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raise TypeError('require_roles param should be a set, but is a %r' % type(require_roles))
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if require_all and not require_roles:
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raise ValueError('require_login(require_all=True) cannot be used with empty require_roles.')
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current_user = g.get('current_user')
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if current_user is None:
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return False
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intersection = require_roles.intersection(current_user['roles'])
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if require_all:
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return len(intersection) == len(require_roles)
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return not bool(require_roles) or bool(intersection)
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def is_admin(user):
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"""Returns True iff the given user has the admin role."""
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return user_has_role(u'admin', user)
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