304 lines
9.0 KiB
Python
304 lines
9.0 KiB
Python
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"""
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Provides a set of pluggable permission policies.
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"""
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from django.http import Http404
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from rest_framework import exceptions
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SAFE_METHODS = ('GET', 'HEAD', 'OPTIONS')
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class OperationHolderMixin:
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def __and__(self, other):
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return OperandHolder(AND, self, other)
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def __or__(self, other):
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return OperandHolder(OR, self, other)
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def __rand__(self, other):
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return OperandHolder(AND, other, self)
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def __ror__(self, other):
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return OperandHolder(OR, other, self)
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def __invert__(self):
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return SingleOperandHolder(NOT, self)
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class SingleOperandHolder(OperationHolderMixin):
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def __init__(self, operator_class, op1_class):
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self.operator_class = operator_class
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self.op1_class = op1_class
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def __call__(self, *args, **kwargs):
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op1 = self.op1_class(*args, **kwargs)
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return self.operator_class(op1)
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class OperandHolder(OperationHolderMixin):
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def __init__(self, operator_class, op1_class, op2_class):
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self.operator_class = operator_class
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self.op1_class = op1_class
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self.op2_class = op2_class
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def __call__(self, *args, **kwargs):
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op1 = self.op1_class(*args, **kwargs)
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op2 = self.op2_class(*args, **kwargs)
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return self.operator_class(op1, op2)
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class AND:
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def __init__(self, op1, op2):
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self.op1 = op1
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self.op2 = op2
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def has_permission(self, request, view):
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return (
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self.op1.has_permission(request, view) and
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self.op2.has_permission(request, view)
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)
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def has_object_permission(self, request, view, obj):
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return (
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self.op1.has_object_permission(request, view, obj) and
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self.op2.has_object_permission(request, view, obj)
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)
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class OR:
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def __init__(self, op1, op2):
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self.op1 = op1
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self.op2 = op2
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def has_permission(self, request, view):
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return (
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self.op1.has_permission(request, view) or
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self.op2.has_permission(request, view)
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)
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def has_object_permission(self, request, view, obj):
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return (
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self.op1.has_permission(request, view)
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and self.op1.has_object_permission(request, view, obj)
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) or (
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self.op2.has_permission(request, view)
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and self.op2.has_object_permission(request, view, obj)
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)
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class NOT:
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def __init__(self, op1):
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self.op1 = op1
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def has_permission(self, request, view):
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return not self.op1.has_permission(request, view)
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def has_object_permission(self, request, view, obj):
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return not self.op1.has_object_permission(request, view, obj)
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class BasePermissionMetaclass(OperationHolderMixin, type):
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pass
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class BasePermission(metaclass=BasePermissionMetaclass):
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"""
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A base class from which all permission classes should inherit.
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"""
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def has_permission(self, request, view):
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"""
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Return `True` if permission is granted, `False` otherwise.
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"""
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return True
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def has_object_permission(self, request, view, obj):
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"""
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Return `True` if permission is granted, `False` otherwise.
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"""
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return True
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class AllowAny(BasePermission):
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"""
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Allow any access.
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This isn't strictly required, since you could use an empty
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permission_classes list, but it's useful because it makes the intention
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more explicit.
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"""
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def has_permission(self, request, view):
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return True
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class IsAuthenticated(BasePermission):
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"""
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Allows access only to authenticated users.
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"""
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def has_permission(self, request, view):
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return bool(request.user and request.user.is_authenticated)
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class IsAdminUser(BasePermission):
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"""
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Allows access only to admin users.
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"""
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def has_permission(self, request, view):
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return bool(request.user and request.user.is_staff)
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class IsAuthenticatedOrReadOnly(BasePermission):
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"""
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The request is authenticated as a user, or is a read-only request.
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"""
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def has_permission(self, request, view):
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return bool(
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request.method in SAFE_METHODS or
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request.user and
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request.user.is_authenticated
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)
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class DjangoModelPermissions(BasePermission):
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"""
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The request is authenticated using `django.contrib.auth` permissions.
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See: https://docs.djangoproject.com/en/dev/topics/auth/#permissions
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It ensures that the user is authenticated, and has the appropriate
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`add`/`change`/`delete` permissions on the model.
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This permission can only be applied against view classes that
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provide a `.queryset` attribute.
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"""
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# Map methods into required permission codes.
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# Override this if you need to also provide 'view' permissions,
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# or if you want to provide custom permission codes.
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perms_map = {
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'GET': [],
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'OPTIONS': [],
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'HEAD': [],
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'POST': ['%(app_label)s.add_%(model_name)s'],
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'PUT': ['%(app_label)s.change_%(model_name)s'],
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'PATCH': ['%(app_label)s.change_%(model_name)s'],
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'DELETE': ['%(app_label)s.delete_%(model_name)s'],
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}
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authenticated_users_only = True
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def get_required_permissions(self, method, model_cls):
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"""
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Given a model and an HTTP method, return the list of permission
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codes that the user is required to have.
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"""
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kwargs = {
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'app_label': model_cls._meta.app_label,
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'model_name': model_cls._meta.model_name
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}
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if method not in self.perms_map:
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raise exceptions.MethodNotAllowed(method)
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return [perm % kwargs for perm in self.perms_map[method]]
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def _queryset(self, view):
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assert hasattr(view, 'get_queryset') \
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or getattr(view, 'queryset', None) is not None, (
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'Cannot apply {} on a view that does not set '
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'`.queryset` or have a `.get_queryset()` method.'
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).format(self.__class__.__name__)
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if hasattr(view, 'get_queryset'):
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queryset = view.get_queryset()
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assert queryset is not None, (
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'{}.get_queryset() returned None'.format(view.__class__.__name__)
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)
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return queryset
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return view.queryset
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def has_permission(self, request, view):
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# Workaround to ensure DjangoModelPermissions are not applied
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# to the root view when using DefaultRouter.
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if getattr(view, '_ignore_model_permissions', False):
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return True
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if not request.user or (
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not request.user.is_authenticated and self.authenticated_users_only):
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return False
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queryset = self._queryset(view)
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perms = self.get_required_permissions(request.method, queryset.model)
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return request.user.has_perms(perms)
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class DjangoModelPermissionsOrAnonReadOnly(DjangoModelPermissions):
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"""
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Similar to DjangoModelPermissions, except that anonymous users are
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allowed read-only access.
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"""
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authenticated_users_only = False
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class DjangoObjectPermissions(DjangoModelPermissions):
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"""
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The request is authenticated using Django's object-level permissions.
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It requires an object-permissions-enabled backend, such as Django Guardian.
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It ensures that the user is authenticated, and has the appropriate
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`add`/`change`/`delete` permissions on the object using .has_perms.
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This permission can only be applied against view classes that
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provide a `.queryset` attribute.
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"""
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perms_map = {
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'GET': [],
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'OPTIONS': [],
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'HEAD': [],
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'POST': ['%(app_label)s.add_%(model_name)s'],
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'PUT': ['%(app_label)s.change_%(model_name)s'],
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'PATCH': ['%(app_label)s.change_%(model_name)s'],
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'DELETE': ['%(app_label)s.delete_%(model_name)s'],
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}
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def get_required_object_permissions(self, method, model_cls):
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kwargs = {
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'app_label': model_cls._meta.app_label,
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'model_name': model_cls._meta.model_name
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}
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if method not in self.perms_map:
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raise exceptions.MethodNotAllowed(method)
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return [perm % kwargs for perm in self.perms_map[method]]
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def has_object_permission(self, request, view, obj):
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# authentication checks have already executed via has_permission
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queryset = self._queryset(view)
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model_cls = queryset.model
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user = request.user
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perms = self.get_required_object_permissions(request.method, model_cls)
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if not user.has_perms(perms, obj):
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# If the user does not have permissions we need to determine if
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# they have read permissions to see 403, or not, and simply see
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# a 404 response.
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if request.method in SAFE_METHODS:
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# Read permissions already checked and failed, no need
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# to make another lookup.
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raise Http404
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read_perms = self.get_required_object_permissions('GET', model_cls)
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if not user.has_perms(read_perms, obj):
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raise Http404
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# Has read permissions.
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return False
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return True
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