This document is part of the Bosch Rexroth ctrlX OS App Development Guideline, and describes which interfaces (port, plugs and slots) are reserved and may not be used by a ctrlX OS App

Please refer to the App Development Guide for further information.

The content of this document may be subject of change in future.

1. Reserved slots and plugs¶

The following operating system interfaces are denied or restricted for usage. See also https://snapcraft.io/docs/supported-interfaces.

Interface	Direction	Parameters	Exceptions	Reason
system-files	Plug	null	"'read=^(\/dev\/shm\| \/dev\/shm\/.+)', 'write=^(\/dev\/shm\| \/dev\/shm\/.+)$'"	Prevent access to system files, except shared memory
account-control	Plug	null	null	Prevent uncontrolled access to user and group databases
snapd-control	Plug	null	null	Prevent uncontrolled access to system configuration
content	Plug	content=package-certificates	null	Prevent apps to act as device admin
content	Plug	content=package-run	null	Prevent apps to act as device admin
content	Slot	content=active-solution	null	Prevent apps to act as solution snap
content	Slot	content=auth-service	null	Prevent unauthorized access, service to service authentication
content	Slot	content=rda-proxy-service	null	Prevent uncontrolled access to proxy service
content	plug	content=rda-proxy-service	null	Prevent unacontrolled access to proxy service
block-devices	plug	null	null	Prevent mounting of partitions
raw-volumes	Plug	null	null	Prevent mounting of partitions
udisk2	Slot	null	null	Prevent mounting of partitions
udisk2	Plug	null	null	Prevent mounting of partitions
docker	Plug	null	null	Prevent access to docker socket
docker-support	Slot	null	null	Prevent operating as the docker daemon because of possibility of privileg escalation
docker-support	Plug	null	null	Prevent operating as the docker daemon because of possibility of privileg escalation
acrn-support	Plug	null	null	Not being supported and potential dangerous
bool-file	Plug	null	null	Bool files are normally located in /sys - no write access to this folder
browser-support	Plug	null	null	Denylist
classic-support	Plug	null	null	Classic support bypass all snapd security mechanism
core-support	Plug	null	null	Deprecated
cpu-control	Plug	null	null	Allows setting CPU tunables
daemon-notify	Plug	null	null	Allows sending daemon status changes to the service manager.
dm-crypt	Plug	null	null	Storage support including encryption is part of the DeviceAdmin
firewall-control	Plug	null	null	Firewall app handles firewall rules
fpga	Plug	null	null	Allows access to fpga subsystem
use-support	Plug	null	null	Allows access to fuse subsyten
fwupd	Plug	null	null	Enabling privileged access to update UEFI firmware
gconf	Plug	null	null	Allows configuration of Gconf, typically used by old GNOME libs
gpg-keys	Plug	null	null	Allows reading GNU Privacy Guard (GPG) user configuration and keys as well as enabling GPG’s random seed to be updated
gpio-control	Plug	null	null	Super-privileged access to gpio pins
gpio-memory-control	Plug	null	null	Allows write access to all GPIO memory
greengrass-support	Plug	null	null	Allows operating as the Greengrass service to access resources and syscalls necessary to run Amazon Greengrass services and lambda functions
hardware-random-control	Plug	null	null	Enables control over the hardware random number generator by allowing read/write access to /dev/hwrng
hidraw	Plug	null	null	Enables raw access to USB and Bluetooth Human Interface (hidraw) devices. This interface is restricted because it provides privileged access to hardware devices
home	Plug	null	"read:all"	Allows access to non-hidden files owned by the user in the user’s home directory. There is no home folder for the users on ctrlX CORE
hugepages-control	Plug	null	null	Handle memory is part of the DeviceAdmin
intel-mei	Plug	null	null	Enables access to the Intel MEI management interface
io-ports-control	Plug	null	null	Allows access to all I/O ports, including the ability to write to /dev/port to change the I/O port permissions, the privilege level of the calling process, and disabling interrupts
ion-memory-control	Plug	null	null	Allows access to the Android ION memory allocator, a Linux kernel feature for managing one or more memory pools
kernel-module-control	Plug	null	null	Provides the ability to insert, remove and query kernel modules. This interface gives privileged access to the device
kernel-module-load	Plug	null	null	Provides the ability to load, or deny loading, specific kernel modules. This interface gives privileged access to the device
kubernetes-support	Plug	null	null	Allows operating as the Kubernetes service and running application containers
kvm	Plug	null	null	Allows access to the /dev/kvm device, providing privileged access and control of the KVM hypervisor
libvirt	Plug	null	null	Enables access to the libvirt control socket, which gives privileged access to control libvirtd on the host
login-session-control	Plug	null	null	Allows setup of login sessions and grants privileged access to user sessions.
lxd	Plug	null	null	Allows access to the LXD API via the socket provided by the lxd snap
lxd-support	Plug	null	null	Enables operating as the LXD service
microstack-support	Plug	null	null	Interface enables multiple service access for the Microstack infrastructure
mount-control	Plug	null	"Except storage-extension concept"	Allows the mounting and unmounting of both transient (non-persistent) and persistent filesystem mount points. This interface gives privileged access to the device
multipass-support	Plug	null	null	Allows operating as the Multipass service
netlink-audit	Plug	null	null	Allows access to the kernel part of the Linux Audit Subsystem through Netlink
netlink-connector	Plug	null	null	Allows communication through the kernel Netlink connector
netlink-driver	Plug	null	null	Allows a kernel module to expose itself to user-space via the Netlink protocol, typically to transfer information between the kernel and user-space processes
network-control	Plug	null	null	Gives access to wifi credentials
network-manager	Plug	null	null	Gives access to wifi credentials
network-manager-observe	Plug	null	null	Gives access to wifi credentials
network-setup-control	Plug	null	null	Gives access to wifi credentials
network-setup-observe	Plug	null	null	Gives access to wifi credentials
packagekit-control	Plug	null	null	Allows control of the PackageKit service, giving privileged access to native package management on the system
password-manager-service	Plug	null	null	Provides access to the global password manager services provided by popular desktop environments, such as Secret Service and Kwallet
personal-files	Plug	null	null	Provides access to the specified files in the user’s home. This interface gives privileged access to the user’s data
physical-memory-control	Plug	null	null	Allows write access the to physical address space via the /dev/mem device
physical-memory-observe	Plug	null	null	Allows read access the to physical address space via the /dev/mem device
polkit-interface	Plug	null	null	Provides daemons with the permission to use the polkit authorisation manager (polkitd) to make access control decisions for requests from unprivileged clients
process-control	Plug	null	null	Prevent tampering with running processes
scsi-generic	Plug	null	null	Allows read and write access to SCSI Generic driver (sg) devices
sd-control	Plug	null	null	Allows for the management and control of SD cards on certain devices using the DualSD driver
shared-memory	Plug	null	"shared-memory=^(datalayer-shm)$"	Allows two snaps to communicate with each other using a specific predefined shared-memory path or directory in /dev/sh
snap-refresh-control	Plug	null, "Exceptions":null	Super privileged interface to allow extended control, via snapctl, of refreshes targeting the snap
ssh-keys	Plug	null	null	Allows a user’s SSH (Secure Socket Shell) configuration to be read, along with both their public and private keys
storage-framework-service	Plug	null	null	Allows operating as, or interacting with, the Storage Framework - storage is part of the DeviceAdmin
system-backup	Plug	null	null	Provides read-only access to the system via /var/lib/snapd/hostfs. This interface gives privileged access to system data
system-trace	Plug	null	null	Enables the monitoring and control of any running program, via kernel tracing facilities. This interface is restricted because it gives privileged access to all processes on the system and should only be used with trusted apps
tee	Plug	null	null	Permits access to Trusted Execution Environment (TEE) devices via the TEE subsystem in the Linux kernel
tpm	Plug	null	null	tpm allows access to the Trusted Platform Module (tpm) device, /dev/tpm0, and to the in-kernel resource manager, /dev/tpmrm0, on recent kernels (at least v4.12)
uhid	Plug	null	null	Enables the creation of kernel USB Human Interface Devices (HID) from user-space, via /dev/uhid , giving privileged access to HID transport drivers
uinput	Plug	null	null	Super privileged interface to allows write access to /dev/uinput on the host system for emulating input devices from userspace that can send input events

2. Blocked ports¶

The following ports are blocked and cannot be used by an app.

Reserved by	Reserved ports
ctrlX OS	22, 80, 81, 443, 1338, 1880, 1900, 2069, 2070, 4840, 5355, 5353, 5858, 6000, 7878, 8069, 11740, 11741
Other apps	1881, 1884, 1885, 2883, 4222, 6123, 7505, 9230, 9240, 8000, 8080, 8088, 8142, 8840, 8883, 10123, 16620, 16700, 16701, 16800, 16810, 18500, 47808, 48898, 49250-50250, 56090, 58000, 51218