Adding Automatic Permissions for New Objects

When creating new objects in either viewsets or tasks it’s important to have the right permissions. It is important that the permissions new objects receive work with the AccessPolicy so that newly created objects can be authorized by the AccessPolicy as expected. The AccessPolicy statements are user-configurable and so the permissions to be created for new objects are too. Similar to the requirements for the AccessPolicy statements, plugin writers can define and ship a default behavior for permissions on new objects, and then users can modify them as needed after migrations are run.

Defining New Object Permission Behaviors

The AccessPolicy.creation_hooks attribute defines a set of callables that are intended to be run when new objects are created. These do not run automatically; your models should use the pulpcore.plugin.models.AutoAddObjPermsMixin on the model as described in the Enabling New Object Permission Creation section.

The AccessPolicy.creation_hooks attribute is optional because not all AccessPolicy objects create objects. If no objects are created by an endpoint, there does not need to be a creation_hooks attribute.

Permissions are associated to users via roles.

The most common auto-assignment of roles is to the creator of an object themselves. Here is an example assigning the "core.task_owner" role to the creator of an object:

{
    "function": "add_roles_for_object_creator",
    "parameters": {"roles": ["core.task_owner"]},
}

Another common auto-assignment of roles is to assign to one or more users explicitly. Here is an example assigning the "core.task_owner" role to the users ["alice", "bob"].

{
    "function": "add_roles_for_users",
    "parameters": {
        "roles": "core.task_owner",
        "users": ["alice", "bob"],
    },
}

A third common auto-assignment of roles is to assign to one or more groups explicitly. Here is an example assigning the "core.task_viewer" role to the group "foo".

{
    "function": "add_roles_for_groups",
    "parameters": {
        "roles": ["core.task_viewer"],
        "groups": "foo",
    },
}

Note

All the hooks shipped with pulpcore accept either a single item or list of items for their arguments like roles, users or groups.

Enabling New Object Permission Creation

To enable automatic permission creation for an object managed by an AccessPolicy, have your model use the pulpcore.plugin.models.AutoAddObjPermsMixin. See the example below as an example:

class MyModel(BaseModel, AutoAddObjPermsMixin):
   ...

See the docstring below for more information on this mixin.

class pulpcore.app.models.access_policy.AutoAddObjPermsMixin(*args, **kwargs)

A mixin that automatically adds roles based on the creation_hooks data.

To use this mixin, your model must support django-lifecycle.

This mixin adds an after_create hook which properly interprets the creation_hooks data and calls methods also provided by this mixin to add roles.

These mixing are provided by default:

• add_for_object_creator will add the permissions to the creator of the object.

• add_for_users will add the permissions for one or more users by name.

• add_for_groups will add the permissions for one or more groups by name.

• add_roles_for_object_creator will add the roles to the creator of the object.

• add_roles_for_users will add the roles for one or more users by name.

• add_roles_for_groups will add the roles for one or more groups by name.

Shipping a Default New Object Policy

In general, the default recommended is to use the add_roles_for_object_creator to assign the view, change, and delete permissions for the object created. Here is an example of a default policy like this:

DEFAULT_ACCESS_POLICY = {
    "statements": <...>
    "creation_hooks": [
        {
            "function": "add_roles_for_object_creator",
            "parameters": {"roles": "file.fileremote_owner"},
        }
    ],
}
LOCKED_ROLES = {
    "file.fileremote_owner": [
        "file.view_fileremote", "file.change_fileremote", "file.delete_fileremote"
    ],
}

This effectively creates a “user isolation” policy which aligns with the examples from Shipping a Default Access Policy.

Defining Custom New Object Permission Callables

Plugin writers can use more than the built-in callables such as add_roles_for_object_creator or add_roles_for_users by defining additional methods on the model itself. The callables defined in the function are method names on the Model that need to be registered with REGISTERED_CREATION_HOOKS:

class MyModel(BaseModel, AutoAddObjPermsMixin):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.REGISTERED_CREATION_HOOKS["my_custom_callable"] = self.my_custom_callable

    def my_custom_callable(self, role, users, groups):
        from pulpcore.app.util import assign_role
        for user in users:
            assign_role(role, user, self)  # self is the object being assigned
        for group in groups:
            assign_role(role, group, self)  # self is the object being assigned

This would be callable with a configuration like this one:

{
    "function": "my_custom_callable",
    "parameters": {
        "role": "pulpcore.task_viewer",
        "users": ["bob"],
        "groups": [],
    },
}

Note

The parameters dict must actually match the creation hooks signature.