libvirt: Client access control
Description: libvirt, virtualization, virtualization API

# Client access control

Libvirt's client access control framework allows administrators to setup fine grained permission rules across client users, managed objects and API operations. This allows client connections to be locked down to a minimal set of privileges.

- Access control introduction
- Access control drivers
- Objects and permissions

## Access control introduction

In a default configuration, the libvirtd daemon has three levels of access control. All connections start off in an unauthenticated state, where the only API operations allowed are those required to complete authentication. After successful authentication, a connection either has full, unrestricted access to all libvirt API calls, or is locked down to only "read only" operations, according to what socket a client connection originated on.

The access control framework allows authenticated connections to have fine grained permission rules to be defined by the administrator. Every API call in libvirt has a set of permissions that will be validated against the object being used. For example, the `virDomainSetSchedulerParametersFlags` method will check whether the client user has the `write` permission on the `domain` object instance passed in as a parameter. Further permissions will also be checked if certain flags are set in the API call. In addition to checks on the object passed in to an API call, some methods will filter their results. For example the `virConnectListAllDomains` method will check the `search_domains` on the `connect` object, but will also filter the returned `domain` objects to only those on which the client user has the `getattr` permission.

## Access control drivers

The access control framework is designed as a pluggable system to enable future integration with arbitrary access control technologies. By default, the `none` driver is used, which does no access control checks at all. At this time, libvirt ships with support for using polkit as a real access control driver. To learn how to use the polkit access driver consult the configuration docs.

The access driver is configured in the `libvirtd.conf` configuration file, using the `access_drivers` parameter. This parameter accepts an array of access control driver names. If more than one access driver is requested, then all must succeed in order for access to be granted. To enable 'polkit' as the driver:

    # augtool -s set '/files/etc/libvirt/libvirtd.conf/access_drivers[1]' polkit

And to reset back to the default (no-op) driver

    # augtool -s rm /files/etc/libvirt/libvirtd.conf/access_drivers

Note: changes to libvirtd.conf require that the libvirtd daemon be restarted.

## Objects and permissions

Libvirt applies access control to all the main object types in its API. Each object type, in turn, has a set of permissions defined. To determine what permissions are checked for specific API call, consult the API reference manual documentation for the API in question.