usbguard-daemon.conf man page
usbguard-daemon.conf — USBGuard daemon configuration file
The usbguard-daemon.conf file is loaded by the USBGuard daemon after it parses its command-line options. It is used to configure runtime parameters of the daemon. The default search path is /etc/usbguard/usbguard-daemon.conf. It may be overridden using the -c command-line option, see usbguard-daemon(8) for further details.
The USBGuard daemon will use this file to load the policy rule set from it and to write new rules received via the Ipc interface.
How to treat USB devices that don’t match any rule in the policy. Target should be one of
reject(logically remove the device node from the system).
How to treat USB devices that are already connected when the daemon starts. Policy should be one of
keep(keep whatever state the device is currently in) or
apply-policy(evaluate the rule set for every present device).
How to treat USB controller devices that are already connected when the daemon starts. One of
How to treat USB devices that are already connected after the daemon starts. One of
The USBGuard daemon modifies some attributes of controller devices like the default authorization state of new child device instances. Using this setting, you can control whether the daemon will try to restore the attribute values to the state before modification on shutdown.
Which device manager backend implementation to use. Backend should be one of
- IPCAllowedUsers*=username [username ...]
A space delimited list of usernames that the daemon will accept Ipc connections from.
- IPCAllowedGroups=groupname [groupname ...]
A space delimited list of groupnames that the daemon will accept Ipc connections from.
The files at this location will be interpreted by the daemon as Ipc access control definition files. See the Ipc Access Control section for more details.
Generate device specific rules including the "via-port" attribute.
USBGuard audit events log backend. The backend value should be one of
USBGuard audit events log file path. Required if AuditBackend is set to
The daemon provides the USBGuard public IPC interface. Depending on your distribution defaults, access to this interface is limited to a certain group or a specific user only. Please set either the IPCAllowedUsers, IPCAllowedGroups or IPCAccessControlFiles options to limit access to the IPC interface. Do not leave the ACL unconfigured as that will expose the IPC interface to all local users and will allow them to manipulate the authorization state of USB devices and modify the USBGuard policy.
RestoreControllerDeviceState configuration option
If set to true, the USB authorization policy could be bypassed by performing some sort of attack on the daemon (via a local exploit or via a USB device) to make it shutdown and restore to the operating-system default state (known to be permissive).
Ipc Access Control
Access to the USBGuard Ipc interface can be limited per user or group. Furthermore, by using the Ipc Access Control files, it is possible to limit the access down to the level of Sections and Privileges as explained below.
When you set IPCAccessControlFiles option, the daemon will look for Ipc access control files in the directory specified by the setting value. Each file in the directory is processed as follows:
1. The basename of the file is interpreted as an username, UID, groupname or GID. If the names starts with
: (colon), it is assumed that the rest of the name represents a group identifier (groupname or GID in case of a numeric-only string). Otherwise, it is interpreted as an user identifier (username or UID in case of numeric-only string).
2. The contents of the file are parsed as
Section=privilege [privilege ...] formatted lines which specify the section privileges. If a section is omitted, it is assumed that no privileges are given for that section.
Available sections and privileges:
- modify: Change authorization state of devices including permanent changes (i.e. modification of device specific rules in the policy).
- list: Ability to get a list of recognized devices and their attributes.
- listen: Listen to device presence and device policy changes.
- modify: Append rules to or remove any rules from the policy.
- list: Ability to view the currently enforced policy.
- listen: Receive exception messages.
- modify: Set values of run-time parameters.
- list: Get values of run-time parameters.
The following is a generally usable and reasonably safe example of an access control file. It allows to modify USB device authorization state (
Devices=modify), list USB devices (
Devices=list), listen to USB device related events (
Devices=listen), list USB authorization policy rules (
Policy=list) and listen to exception events (
Devices=modify list listen Policy=list Exceptions=listen
Instead of creating the access control files by yourself, you can use the
usbguard add-user or
usbguard remove-user CLI commands. See usbguard(1) for more details.
Legacy: IPCAllowedUsers and IPCAllowedGroups
Example configuration allowing full Ipc access to users root, joe and members of the group wheel:
IPCAllowedUsers=root joe IPCAllowedGroups=wheel
Unresolved directive in usbguard-daemon.conf.5.adoc - include::footer.adoc
usbguard(1), usbguard-applet-qt(1), usbguard-daemon(8), usbguard-rules.conf(5).