mirror of
https://gitlab.com/libvirt/libvirt.git
synced 2024-12-23 21:34:54 +03:00
c0a06c081c
The only special bit about the 'acl' page was the inclusion of the objects and permissions tables. We can do that by the '.. raw::' directive. One reference from 'aclpolkit.rst' needed to be updated to go with the new header anchor naming. Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
311 lines
12 KiB
ReStructuredText
311 lines
12 KiB
ReStructuredText
.. role:: since
|
|
|
|
=====================
|
|
Polkit access control
|
|
=====================
|
|
|
|
Libvirt's client `access control framework <acl.html>`__ 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. The polkit
|
|
driver provides a simple implementation of the access control framework.
|
|
|
|
.. contents::
|
|
|
|
Introduction
|
|
------------
|
|
|
|
A default install of libvirt will typically use
|
|
`polkit <https://www.freedesktop.org/wiki/Software/polkit/>`__ to
|
|
authenticate the initial user connection to libvirtd. This is a very
|
|
coarse grained check though, either allowing full read-write access to
|
|
all APIs, or just read-only access. The polkit access control driver in
|
|
libvirt builds on this capability to allow for fine grained control over
|
|
the operations a user may perform on an object.
|
|
|
|
Permission names
|
|
----------------
|
|
|
|
The libvirt `object names and permission names <acl.html#objects-and-permissions>`__ are
|
|
mapped onto polkit action names using the simple pattern:
|
|
|
|
::
|
|
|
|
org.libvirt.api.$object.$permission
|
|
|
|
The only caveat is that any underscore characters in the object or
|
|
permission names are converted to hyphens. So, for example, the
|
|
``search_storage_vols`` permission on the ``storage_pool`` object maps
|
|
to the polkit action:
|
|
|
|
::
|
|
|
|
org.libvirt.api.storage-pool.search-storage-vols
|
|
|
|
The default policy for any permission which corresponds to a "read only"
|
|
operation, is to allow access. All other permissions default to deny
|
|
access.
|
|
|
|
Object identity attributes
|
|
--------------------------
|
|
|
|
To allow polkit authorization rules to be written to match against
|
|
individual object instances, libvirt provides a number of authorization
|
|
detail attributes when performing a permission check. The set of
|
|
attributes varies according to the type of object being checked
|
|
|
|
virConnectPtr
|
|
~~~~~~~~~~~~~
|
|
|
|
============== =====================================
|
|
Attribute Description
|
|
============== =====================================
|
|
connect_driver Name of the libvirt connection driver
|
|
============== =====================================
|
|
|
|
virDomainPtr
|
|
~~~~~~~~~~~~
|
|
|
|
============== ============================================
|
|
Attribute Description
|
|
============== ============================================
|
|
connect_driver Name of the libvirt connection driver
|
|
domain_name Name of the domain, unique to the local host
|
|
domain_uuid UUID of the domain, globally unique
|
|
============== ============================================
|
|
|
|
virInterfacePtr
|
|
~~~~~~~~~~~~~~~
|
|
|
|
+-------------------+---------------------------------------------------------+
|
|
| Attribute | Description |
|
|
+===================+=========================================================+
|
|
| connect_driver | Name of the libvirt connection driver |
|
|
+-------------------+---------------------------------------------------------+
|
|
| interface_name | Name of the network interface, unique to the local host |
|
|
+-------------------+---------------------------------------------------------+
|
|
| interface_macaddr | MAC address of the network interface, not unique |
|
|
+-------------------+---------------------------------------------------------+
|
|
|
|
virNetworkPtr
|
|
~~~~~~~~~~~~~
|
|
|
|
============== =============================================
|
|
Attribute Description
|
|
============== =============================================
|
|
connect_driver Name of the libvirt connection driver
|
|
network_name Name of the network, unique to the local host
|
|
network_uuid UUID of the network, globally unique
|
|
============== =============================================
|
|
|
|
virNodeDevicePtr
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
================ =================================================
|
|
Attribute Description
|
|
================ =================================================
|
|
connect_driver Name of the libvirt connection driver
|
|
node_device_name Name of the node device, unique to the local host
|
|
================ =================================================
|
|
|
|
virNWFilterPtr
|
|
~~~~~~~~~~~~~~
|
|
|
|
============== ====================================================
|
|
Attribute Description
|
|
============== ====================================================
|
|
connect_driver Name of the libvirt connection driver
|
|
nwfilter_name Name of the network filter, unique to the local host
|
|
nwfilter_uuid UUID of the network filter, globally unique
|
|
============== ====================================================
|
|
|
|
virSecretPtr
|
|
~~~~~~~~~~~~
|
|
|
|
=================== ===========================================
|
|
Attribute Description
|
|
=================== ===========================================
|
|
connect_driver Name of the libvirt connection driver
|
|
secret_uuid UUID of the secret, globally unique
|
|
secret_usage_volume Name of the associated volume, if any
|
|
secret_usage_ceph Name of the associated Ceph server, if any
|
|
secret_usage_target Name of the associated iSCSI target, if any
|
|
secret_usage_name Name of the associated TLS secret, if any
|
|
=================== ===========================================
|
|
|
|
virStoragePoolPtr
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
============== ==================================================
|
|
Attribute Description
|
|
============== ==================================================
|
|
connect_driver Name of the libvirt connection driver
|
|
pool_name Name of the storage pool, unique to the local host
|
|
pool_uuid UUID of the storage pool, globally unique
|
|
============== ==================================================
|
|
|
|
virStorageVolPtr
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
============== ==================================================
|
|
Attribute Description
|
|
============== ==================================================
|
|
connect_driver Name of the libvirt connection driver
|
|
pool_name Name of the storage pool, unique to the local host
|
|
pool_uuid UUID of the storage pool, globally unique
|
|
vol_name Name of the storage volume, unique to the pool
|
|
vol_key Key of the storage volume, globally unique
|
|
============== ==================================================
|
|
|
|
Hypervisor Driver connect_driver
|
|
--------------------------------
|
|
|
|
The ``connect_driver`` parameter describes the client's `remote
|
|
Connection Driver <remote.html>`__ name based on the `URI <uri.html>`__
|
|
used for the connection.
|
|
|
|
:since:`Since 4.1.0`, when calling an API outside the scope of the primary
|
|
connection driver, the primary driver will attempt to open a secondary
|
|
connection to the specific API driver in order to process the API. For
|
|
example, when hypervisor domain processing needs to make an API call
|
|
within the storage driver or the network filter driver an attempt to
|
|
open a connection to the "storage" or "nwfilter" driver will be made.
|
|
Similarly, a "storage" primary connection may need to create a
|
|
connection to the "secret" driver in order to process secrets for the
|
|
API. If successful, then calls to those API's will occur in the
|
|
``connect_driver`` context of the secondary connection driver rather
|
|
than in the context of the primary driver. This affects the
|
|
``connect_driver`` returned from rule generation from the
|
|
``action.loookup`` function. The following table provides a list of the
|
|
various connection drivers and the ``connect_driver`` name used by each
|
|
regardless of primary or secondary connection. The access denied error
|
|
message from libvirt will list the connection driver by name that denied
|
|
the access.
|
|
|
|
Connection Driver Name
|
|
~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
================= =======================
|
|
Connection Driver ``connect_driver`` name
|
|
================= =======================
|
|
bhyve bhyve
|
|
esx ESX
|
|
hyperv Hyper-V
|
|
interface interface
|
|
xen Xen
|
|
lxc LXC
|
|
network network
|
|
nodedev nodedev
|
|
nwfilter NWFilter
|
|
openvz OPENVZ
|
|
qemu QEMU
|
|
secret secret
|
|
storage storage
|
|
vbox VBOX
|
|
vmware VMWARE
|
|
vz vz
|
|
================= =======================
|
|
|
|
User identity attributes
|
|
------------------------
|
|
|
|
At this point in time, the only attribute provided by libvirt to
|
|
identify the user invoking the operation is the PID of the client
|
|
program. This means that the polkit access control driver is only useful
|
|
if connections to libvirt are restricted to its UNIX domain socket. If
|
|
connections are being made to a TCP socket, no identifying information
|
|
is available and access will be denied. Also note that if the client is
|
|
connecting via an SSH tunnel, it is the local SSH user that will be
|
|
identified. In future versions, it is expected that more information
|
|
about the client user will be provided, including the SASL / Kerberos
|
|
username and/or x509 distinguished name obtained from the authentication
|
|
provider in use.
|
|
|
|
Writing access control policies
|
|
-------------------------------
|
|
|
|
If using versions of polkit prior to 0.106 then it is only possible to
|
|
validate (user, permission) pairs via the ``.pkla`` files. Fully
|
|
validation of the (user, permission, object) triple requires the new
|
|
JavaScript ``.rules`` support that was introduced in version 0.106. The
|
|
latter is what will be described here.
|
|
|
|
Libvirt does not ship any rules files by default. It merely provides a
|
|
definition of the default behaviour for each action (permission). As
|
|
noted earlier, permissions which correspond to read-only operations in
|
|
libvirt will be allowed to all users by default; everything else is
|
|
denied by default. Defining custom rules requires creation of a file in
|
|
the ``/etc/polkit-1/rules.d`` directory with a name chosen by the
|
|
administrator (``100-libvirt-acl.rules`` would be a reasonable choice).
|
|
See the ``polkit(8)`` manual page for a description of how to write
|
|
these files in general. The key idea is to create a file containing
|
|
something like
|
|
|
|
::
|
|
|
|
polkit.addRule(function(action, subject) {
|
|
....logic to check 'action' and 'subject'...
|
|
});
|
|
|
|
In this code snippet above, the ``action`` object instance will
|
|
represent the libvirt permission being checked along with identifying
|
|
attributes for the object it is being applied to. The ``subject``
|
|
meanwhile will identify the libvirt client app (with the caveat above
|
|
about it only dealing with local clients connected via the UNIX socket).
|
|
On the ``action`` object, the permission name is accessible via the
|
|
``id`` attribute, while the object identifying attributes are exposed
|
|
via the ``lookup`` method.
|
|
|
|
See `source
|
|
code <https://gitlab.com/libvirt/libvirt/-/tree/master/examples/polkit>`__
|
|
for a more complex example.
|
|
|
|
Example: restricting ability to connect to drivers
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Consider a local user ``berrange`` who has been granted permission to
|
|
connect to libvirt in full read-write mode. The goal is to only allow
|
|
them to use the ``QEMU`` driver and not the Xen or LXC drivers which are
|
|
also available in libvirtd. To achieve this we need to write a rule
|
|
which checks whether the ``connect_driver`` attribute is ``QEMU``, and
|
|
match on an action name of ``org.libvirt.api.connect.getattr``. Using
|
|
the javascript rules format, this ends up written as
|
|
|
|
::
|
|
|
|
polkit.addRule(function(action, subject) {
|
|
if (action.id == "org.libvirt.api.connect.getattr" &&
|
|
subject.user == "berrange") {
|
|
if (action.lookup("connect_driver") == 'QEMU') {
|
|
return polkit.Result.YES;
|
|
} else {
|
|
return polkit.Result.NO;
|
|
}
|
|
}
|
|
});
|
|
|
|
Example: restricting access to a single domain
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Consider a local user ``berrange`` who has been granted permission to
|
|
connect to libvirt in full read-write mode. The goal is to only allow
|
|
them to see the domain called ``demo`` on the LXC driver. To achieve
|
|
this we need to write a rule which checks whether the ``connect_driver``
|
|
attribute is ``LXC`` and the ``domain_name`` attribute is ``demo``, and
|
|
match on an action name of ``org.libvirt.api.domain.getattr``. Using the
|
|
javascript rules format, this ends up written as
|
|
|
|
::
|
|
|
|
polkit.addRule(function(action, subject) {
|
|
if (action.id == "org.libvirt.api.domain.getattr" &&
|
|
subject.user == "berrange") {
|
|
if (action.lookup("connect_driver") == 'LXC' &&
|
|
action.lookup("domain_name") == 'demo') {
|
|
return polkit.Result.YES;
|
|
} else {
|
|
return polkit.Result.NO;
|
|
}
|
|
}
|
|
});
|