kernel-module-load interface

kernel-module-load provides the ability to load, or deny loading, specific kernel modules. This interface gives privileged access to the device.

See also the kernel-module-control interface for inserting, removing and querying kernel modules.

Developer details

Auto-connect: no
Super-privileged: yes

Caution

This interface controls a resource shared by the whole system. Snaps that use it can be installed as parallel instances, but every instance acts on the same system resource and snapd does not coordinate between them. Make sure each instance manages different resources, or run only one instance at a time. See Snaps that are unsupported as parallel instances for details..

Attributes:

  • name (plug, required): provides the name of the kernel module to be loaded (eg, ‘name: pcspkr’)

  • load (plug): string to declare when, or whether, to load this module. Values can be one of the following:

    • on-boot (default): loads the kernel module at boot time (eg. load: on-boot)

    • denied: prevents the module from being loaded at all (eg. load: denied). Also known as denylisting in the Linux kernel.

    • dynamic: enables runtime loading and unloading of the kernel module. The snap can load and unload the module using snapctl kmod.

  • options (plug): string of options to use when loading the module (eg, options: p1=3 p2=true p3)

In addition to the name attribute being required, either options or load must also be specified.

Consumers of this interface require a snap declaration for distribution via the Snap Store.

Requires snapd version 2.54+.

Code examples

The following is an example snippet for an application snap to load the module foo with options param=2, and to deny loading the module bar:

plugs:
  load-foo:
    interface: kernel-module-load
    modules:
    - name: foo
      options: param=2
  deny-bar:
    interface: kernel-module-load
    modules:
    - name: bar
      load: denied

The load-foo foo kernel module can be more verbosely by declared with the load attribute, resulting in the same behaviour:

plugs:
  load-foo:
    interface: kernel-module-load
    modules:
    - name: foo
      load: on-boot
      options: param=2

The test code can be found in the snapd repository: https://github.com/canonical/snapd/blob/master/interfaces/builtin/kernel_module_load.go

The source code for the interface is in the snapd repository:https://github.com/canonical/snapd/blob/master/interfaces/builtin/kernel_module_load_test.go