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174 Disposable customization

Introduction

A disposable can be based on any app qube. You can also choose to use different disposable templates for different disposables. To prepare an app qube to be a disposable template, you need to set template_for_dispvms property, for example:

[user@dom0 ~]$ qvm-prefs fedora-26-dvm template_for_dispvms True

Additionally, if you want to have menu entries for starting applications in disposable based on this app qube (instead of in the app qube itself), you can achieve it with appmenus-dispvm feature:

[user@dom0 ~]$ qvm-features fedora-26-dvm appmenus-dispvm 1

Note: application shortcuts that existed before setting this feature will not be updated automatically. Please go the the "Applications" tab in the qube's "Settings" dialog and unselect all existing shortcuts by clicking "<<", then click "OK" and close the dialog. Give it a few seconds time and then reopen and re-select all the shortcuts you want to see in the menu. See this page for background information.

Security

If a disposable template becomes compromised, then any disposable based on that disposable template could be compromised. Therefore, you should not make any risky customizations (e.g., installing untrusted browser plugins) in important disposable templates. In particular, the default disposable template is important because it is used by the "Open in disposable" feature. This means that it will have access to everything that you open with this feature. For this reason, it is strongly recommended that you base the default disposable template on a trusted template and refrain from making any risky customizations to it.

Creating a new disposable template

In Qubes 4.0, you're no longer restricted to a single disposable template. Instead, you can create as many as you want. Whenever you start a new disposable, you can choose to base it on whichever disposable template you like. To create new disposable template, lets say custom-disposable-template, based on debian-9 template, use following commands:

[user@dom0 ~]$ qvm-create --template debian-9 --label red custom-disposable-template
[user@dom0 ~]$ qvm-prefs custom-disposable-template template_for_dispvms True
[user@dom0 ~]$ qvm-features custom-disposable-template appmenus-dispvm 1

Additionally you may want to set it as default disposable template:

[user@dom0 ~]$ qubes-prefs default_dispvm custom-disposable-template

The above default is used whenever a qube request starting a new disposable and do not specify which one (for example qvm-open-in-dvm tool). This can be also set in qube settings and will affect service calls from that qube. See qrexec documentation for details.

If you wish to use a Minimal Template as a disposable template, please see the Minimal Template page.

Customization of disposable

Note: If you are trying to customize Tor Browser in a Whonix disposable, please consult the Whonix documentation.

It is possible to change the settings for each new disposable. This can be done by customizing the disposable template on which it is based:

  1. Start a terminal in the fedora-26-dvm qube (or another disposable template) by running the following command in a dom0 terminal. (If you enable appmenus-dispvm feature (as explained at the top), applications menu for this VM (fedora-26-dvm) will be "Disposable: fedora-26-dvm" (instead of "Domain: fedora-26-dvm") and entries there will start new disposable based on that VM (fedora-26-dvm). Not in that VM (fedora-26-dvm) itself).

    [user@dom0 ~]$ qvm-run -a fedora-26-dvm gnome-terminal

  2. Change the qube's settings and/or applications, as desired. Some examples of changes you may want to make include:

    • Changing Firefox's default startup settings and homepage.
    • Changing default editor, image viewer. In Debian-based templates this can be done with the mimeopen command.
    • Changing the disposable's default NetVM. For example, you may wish to set the NetVM to "none." Then, whenever you start a new disposable, you can choose your desired ProxyVM manually (by changing the newly-started disposables settings). This is useful if you sometimes wish to use a disposable with a Whonix Gateway, for example. It is also useful if you sometimes wish to open untrusted files in a network-disconnected disposable.

  3. Shutdown the qube (either by poweroff from qube's terminal, or qvm-shutdown from dom0 terminal).

Using named disposables for sys-*

You can use a named disposable for sys-* as long as it is stateless. For example, a sys-net using DHCP or sys-usb will work. In most cases sys-firewall will also work, even if you have configured app qube firewall rules. The only exception is if you require something like VM to VM communication and have manually edited iptables or other items directly inside the firewall app qube.

To create one that has no PCI devices attached, such as for sys-firewall:

qvm-create -C DispVM -l green <sys-VMName>
qvm-prefs <sys-VMName> autostart true
qvm-prefs <sys-VMName> netvm <sys-net>
qvm-prefs <sys-VMName> provides_network true
qvm-features <sys-VMName> appmenus-dispvm ''

Next, set the old sys-firewall autostart to false, and update any references to the old one to instead point to the new. For example, with qvm-prefs work netvm sys-firewall2.

To create one with a PCI device attached such as for sys-net or sys-usb, use the additional commands as follows.

Note You can use qvm-pci to determine the <BDF>. Also, you will often need to include the -o no-strict-reset=True option with USB controllers.

qvm-create -C DispVM -l red <sys-VMName>
qvm-prefs <sys-VMName> virt_mode hvm
qvm-service <sys-VMName> meminfo-writer off
qvm-pci attach --persistent <sys-VMName> dom0:<BDF>
qvm-prefs <sys-VMName> autostart true
qvm-prefs <sys-VMName> netvm ''
qvm-features <sys-VMName> appmenus-dispvm ''
# optional, if this disposable will be providing networking
qvm-prefs <sys-VMName> provides_network true

Next, set the old sys- VM's autostart to false, and update any references to the old one. In particular, make sure to update /etc/qubes-rpc/policy/qubes.UpdatesProxy in dom0.

For example, qvm-prefs sys-firewall netvm <sys-VMName>. See below for a complete example of a sys-net replacement:

qvm-create -C DispVM -l red sys-net2
qvm-prefs sys-net2 virt_mode hvm
qvm-service sys-net2 meminfo-writer off
qvm-pci attach --persistent sys-net2 dom0:00_1a.0
qvm-prefs sys-net2 autostart true
qvm-prefs sys-net2 netvm ''
qvm-features sys-net2 appmenus-dispvm ''
qvm-prefs sys-net2 provides_network true
qvm-prefs sys-net autostart false
qvm-prefs sys-firewall netvm sys-net2
qubes-prefs clockvm sys-net2

Adding programs to disposable Application Menu

For added convenience, arbitrary programs can be added to the Application Menu of the disposable.

In order to do that, select "Qube settings" entry in selected base app qube, go to "Applications" tab and select desired applications as for any other qube.

Note that currently only applications whose main process keeps running until you close the application (i.e. do not start a background process instead) will work. One of known examples of incompatible applications is GNOME Terminal (shown on the list as "Terminal"). Choose different terminal emulator (like XTerm) instead.

Create Custom sys-net sys-firewall and sys-usb disposables

Users have the option of creating customized disposables for the sys-net, sys-firewall and sys-usb VMs. In this configuration, a fresh VM instance is created each time a disposable is launched. Functionality is near-identical to the default VMs created following a new Qubes’ installation, except the user benefits from a non-persistent filesystem.

Functionality is not limited, users can:

  • Set custom firewall rule sets and run Qubes VPN scripts.
  • Set disposables to autostart at system boot.
  • Attach PCI devices with the --persistent option.

Using disposables in this manner is ideal for untrusted qubes which require persistent PCI devices, such as USB VMs and NetVMs.

Note: Users who want customized VPN or firewall rule sets must create a separate disposable template for use by each disposable. If disposable template customization is not needed, then a single disposable template is used as a template for all disposables.

Create and configure the disposable template on which the disposable will be based

  1. Create the disposable template:

    [user@dom0 ~]$ qvm-create --class AppVM --label gray <disposable-Template-Name>

  2. (optional) In the disposable template, add custom firewall rule sets, Qubes VPN scripts, etc.

    Firewall rules sets and Qubes VPN scripts can be added just like any other VM.

  3. Set the disposable template as template for disposables:

    [user@dom0 ~]$ qvm-prefs <disposable-Template-Name> template_for_dispvms true

Create the sys-net disposable

  1. Create sys-net disposable based on the disposable template:

    [user@dom0 ~]$ qvm-create --template <disposable-Template-Name> --class DispVM --label red disp-sys-net

  2. Set disp-sys-net virtualization mode to hvm:

    [user@dom0 ~]$ qvm-prefs disp-sys-net virt_mode hvm

  3. Set disp-sys-net to provide network for other VMs:

    [user@dom0 ~]$ qvm-prefs disp-sys-net provides_network true

  4. Set disp-sys-net NetVM to none:

    [user@dom0 ~]$ qvm-prefs disp-sys-net netvm ""

  5. List all available PCI devices to determine the correct backend:BDF address(es) to assign to disp-sys-net:

    [user@dom0 ~]$ qvm-pci

  6. Attach the network PCI device(s) to disp-sys-net (finding and assigning PCI devices can be found here:

    [user@dom0 ~]$ qvm-pci attach --persistent disp-sys-net <backend>:<bdf>

  7. (recommended) Set disp-sys-net to start automatically when Qubes boots:

    [user@dom0 ~]$ qvm-prefs disp-sys-net autostart true

  8. (recommended) Disable the appmenus-dispvm feature, as disp-sys-net is not itself a disposable template (Note: this is only necessary if you enabled the appmenus-dispvm feature for the disposable template):

    [user@dom0 ~]$ qvm-features disp-sys-net appmenus-dispvm ''

  9. (optional) Set disp-sys-net as the dom0 time source:

    [user@dom0 ~]$ qubes-prefs clockvm disp-sys-net

  10. (recommended) Allow templates to be updated via disp-sys-net. In dom0, edit /etc/qubes-rpc/policy/qubes.UpdatesProxy to change the target from sys-net to disp-sys-net.

Create the sys-firewall disposable

  1. Create sys-firewall disposable:

    [user@dom0 ~]$ qvm-create --template <disposable-Template-Name> --class DispVM --label green disp-sys-firewall

  2. Set disp-sys-firewall to provide network for other VMs:

    [user@dom0 ~]$ qvm-prefs disp-sys-firewall provides_network true

  3. Set disp-sys-net as the NetVM for disp-sys-firewall:

    [user@dom0 ~]$ qvm-prefs disp-sys-firewall netvm disp-sys-net

  4. Set disp-sys-firewall as NetVM for other app qubes:

    [user@dom0 ~]$ qvm-prefs <vm_name> netvm disp-sys-firewall

  5. (recommended) Set disp-sys-firewall to auto-start when Qubes boots:

    [user@dom0 ~]$ qvm-prefs disp-sys-firewall autostart true

  6. (recommended) Disable the appmenus-dispvm feature, as disp-sys-firewall is not itself a disposable template (Note: this is only necessary if you enabled the appmenus-dispvm feature for the disposable template):

    [user@dom0 ~]$ qvm-features disp-sys-firewall appmenus-dispvm ''

  7. (optional) Set disp-sys-firewall as the default NetVM:

    [user@dom0 ~]$ qubes-prefs default_netvm disp-sys-firewall

Create the sys-usb disposable

  1. Create the disp-sys-usb:

    [user@dom0 ~]$ qvm-create --template <disposable-template-name> --class DispVM --label red disp-sys-usb

  2. Set the disp-sys-usb virtualization mode to hvm:

    [user@dom0 ~]$ qvm-prefs disp-sys-usb virt_mode hvm

  3. Set disp-sys-usb NetVM to none:

    [user@dom0 ~]$ qvm-prefs disp-sys-usb netvm ""

  4. List all available PCI devices:

    [user@dom0 ~]$ qvm-pci

  5. Attach the USB controller to the disp-sys-usb:

    Note: Most of the commonly used USB controllers (all Intel integrated controllers) require the -o no-strict-reset=True option to be set. Instructions detailing how this option is set can be found here.

    [user@dom0 ~]$ qvm-pci attach --persistent disp-sys-usb <backined>:<bdf>

  6. (optional) Set disp-sys-usb to auto-start when Qubes boots:

    [user@dom0 ~]$ qvm-prefs disp-sys-usb autostart true

  7. (recommended) Disable the appmenus-dispvm feature, as disp-sys-usb is not itself a disposable template (Note: this is only necessary if you enabled the appmenus-dispvm feature for the disposable template):

    [user@dom0 ~]$ qvm-features disp-sys-usb appmenus-dispvm ''

  8. Users should now follow instructions on How to hide USB controllers from dom0.

  9. At this point, your mouse may not work. Edit the qubes.InputMouse policy file in dom0, which is located here:

    /etc/qubes-rpc/policy/qubes.InputMouse

    Add a line like this to the top of the file:

    disp-sys-usb dom0 allow,user=root

Starting the disposables

Prior to starting the new VMs, users should ensure that no other VMs such as the old sys-net and sys-usb VMs are running. This is because no two VMs can share the same PCI device while both running. It is recommended that users detach the PCI devices from the old VMs without deleting them. This will allow users to reattach the PCI devices if the newly created disposables fail to start.

Detach PCI device from VM:

[user@dom0~]$ qvm-pci detach <vm_name> <backend>:<bdf>

Troubleshooting

If the disp-sys-usb does not start, it could be due to a PCI passthrough problem. For more details on this issue along with possible solutions, users can look here.

Deleting disposables

While working in a disposable, you may want to open a document in another disposable. For this reason, the property default_dispvm may be set to the name of your disposable in a number of VMs:

[user@dom0 ~]$ qvm-prefs workvm | grep default_dispvm
default_dispvm        -  custom-disposable-template

This will prevent the deletion of the disposable template. In order to fix this you need to unset the default_dispvm property:

[user@dom0 ~]$ qvm-prefs workvm default_dispvm ""

You can then delete the disposable template:

[user@dom0 ~]$ qvm-remove custom-disposable-template
This will completely remove the selected VM(s)
  custom-disposable-template

If you still encounter the issue, you may have forgot to clean an entry. Looking at the system logs will help you:

[user@dom0 ~]$ journalctl | tail