django setear permisos con has_perm

[minimal]

hola como estan tengo mi autenciacion bakend en django y quiero chekear que cuadno el usuario sea del staf retorne que no se puede logear en frontend

este es mi backend

Código Python:

class  CustomBackend(object):
 
    def authenticate(self, username=None, password=None):
        UserModel = get_user_model()
        if username is None:
            username = kwargs.get(UserModel.USERNAME_FIELD)
        try:
            user =  UserModel._default_manager.get_by_natural_key(username)
            if user.check_password(password):
                return user
        except UserModel.DoesNotExist:
            UserModel().set_password(password)
        
    def has_perm(self, user_obj, perm, obj=None):
        if user_obj.is_staf:
            return False
        else:
            return True
 
    def get_user(self, user_id):
        UserModel = get_user_model()
        try:
            return UserModel._default_manager.get(pk=user_id)
        except UserModel.DoesNotExist:
            return None
 

Bakend Original de django el que usa django por defecto

Código Python:

from __future__ import unicode_literals
from django.contrib.auth import get_user_model
from django.contrib.auth.models import Permission
 
 
class ModelBackend(object):
    """
    Authenticates against settings.AUTH_USER_MODEL.
    """
 
    def authenticate(self, username=None, password=None, **kwargs):
        UserModel = get_user_model()
        if username is None:
            username = kwargs.get(UserModel.USERNAME_FIELD)
        try:
            user = UserModel._default_manager.get_by_natural_key(username)
            if user.check_password(password):
                return user
        except UserModel.DoesNotExist:
            # Run the default password hasher once to reduce the timing
            # difference between an existing and a non-existing user (#20760).
            UserModel().set_password(password)
 
    def get_group_permissions(self, user_obj, obj=None):
        """
        Returns a set of permission strings that this user has through his/her
        groups.
        """
        if user_obj.is_anonymous() or obj is not None:
            return set()
        if not hasattr(user_obj, '_group_perm_cache'):
            if user_obj.is_superuser:
                perms = Permission.objects.all()
            else:
                user_groups_field = get_user_model()._meta.get_field('groups')
                user_groups_query = 'group__%s' % user_groups_field.related_query_name()
                perms = Permission.objects.filter(**{user_groups_query: user_obj})
            perms = perms.values_list('content_type__app_label', 'codename').order_by()
            user_obj._group_perm_cache = set("%s.%s" % (ct, name) for ct, name in perms)
        return user_obj._group_perm_cache
 
    def get_all_permissions(self, user_obj, obj=None):
        if user_obj.is_anonymous() or obj is not None:
            return set()
        if not hasattr(user_obj, '_perm_cache'):
            user_obj._perm_cache = set("%s.%s" % (p.content_type.app_label, p.codename) for p in user_obj.user_permissions.select_related())
            user_obj._perm_cache.update(self.get_group_permissions(user_obj))
        return user_obj._perm_cache
 
    def has_perm(self, user_obj, perm, obj=None):
        if not user_obj.is_active:
            return False
        return perm in self.get_all_permissions(user_obj, obj)
 
    def has_module_perms(self, user_obj, app_label):
        """
        Returns True if user_obj has any permissions in the given app_label.
        """
        if not user_obj.is_active:
            return False
        for perm in self.get_all_permissions(user_obj):
            if perm[:perm.index('.')] == app_label:
                return True
        return False
 
    def get_user(self, user_id):
        UserModel = get_user_model()
        try:
            return UserModel._default_manager.get(pk=user_id)
        except UserModel.DoesNotExist:
            return None