Installing and updating software in domUs

Updating domUs, especially TemplateVMs and StandaloneVMs are important steps in Updating Qubes OS. It is very import to keep domUs up-to-date with the latest security updates. Updating these VMs also allows you to receive various non-security bug fixes and enhancements both from the Qubes OS Project and from your upstream distro maintainer.

Installing software in TemplateVMs

To permanently install new software in a TemplateVM:

  1. Start the TemplateVM.
  2. Start either a terminal (e.g. gnome-terminal) or a dedicated software management application, such as gpk-application.
  3. Install software as normally instructed inside that operating system (e.g. using dnf, or the dedicated GUI application).
  4. Shut down the TemplateVM.
  5. Restart all TemplateBasedVMs based on the TemplateVM.

Updating software in TemplateVMs

The recommended way to update your TemplateVMs is to use the Qubes Update tool. By default, the icon for this tool will appear in your Notification Area when updates are available. Simply click on it and follow the guided steps. If you wish to open this tool directly, you can find it in the System Tools area of the Applications menu.

You can also update TemplateVMs individually. In the Qube Manager, select the desired TemplateVM, then click Update qube. Advanced users can execute the standard update command for that operating system from the command line, e.g. dnf update in Fedora and apt-get update in Debian.

Testing repositories

If you wish to install updates that are still in testing, you must enable the appropriate testing repositories.

Fedora

There are three Qubes VM testing repositories (where * denotes the Release):

  • qubes-vm-*-current-testing – testing packages that will eventually land in the stable (current) repository
  • qubes-vm-*-security-testing – a subset of qubes-vm-*-current-testing that contains packages that qualify as security fixes
  • qubes-vm-*-unstable – packages that are not intended to land in the stable (qubes-vm-*-current) repository; mostly experimental debugging packages

To temporarily enable any of these repos, use the --enablerepo=<repo-name> option. Example commands:

sudo dnf upgrade --enablerepo=qubes-vm-*-current-testing
sudo dnf upgrade --enablerepo=qubes-vm-*-security-testing
sudo dnf upgrade --enablerepo=qubes-vm-*-unstable

To enable or disable any of these repos permanently, change the corresponding enabled value to 1 in /etc/yum.repos.d/qubes-*.repo.

Debian

Debian also has three Qubes VM testing repositories (where * denotes the Release):

  • *-testing – testing packages that will eventually land in the stable (current) repository
  • *-securitytesting – a subset of *-testing that contains packages that qualify as security fixes
  • *-unstable – packages that are not intended to land in the stable repository; mostly experimental debugging packages

To enable or disable any of these repos permanently, uncomment the corresponding deb line in /etc/apt/sources.list.d/qubes-r*.list.

StandaloneVMs

When you create a StandaloneVM from a TemplateVM, the StandaloneVM is a complete clone of the TemplateVM, including the entire filesystem. After the moment of creation, the StandaloneVM is completely independent from the TemplateVM. Therefore, it will not be updated when the TemplateVM is updated. Rather, it must be updated individually. The process for installing and updating software in StandaloneVMs is the same as described above for TemplateVMs.

Advanced

The following sections cover advanced topics pertaining to installing and updating software in domUs.

RPMFusion for Fedora TemplateVMs

If you would like to enable the RPM Fusion repository, open a Terminal of the TemplateVM and type the following commands:

sudo dnf config-manager --set-enabled rpmfusion-free rpmfusion-nonfree
sudo dnf upgrade --refresh

Reverting changes to a TemplateVM

Perhaps you’ve just updated your TemplateVM, and the update broke your template. Or perhaps you’ve made a terrible mistake, like accidentally confirming the installation of an unsigned package that could be malicious. If you want to undo changes to a TemplateVM, there are three basic methods:

  1. Root revert. This is appropriate for misconfigurations, but not for security concerns. It will preserve your customizations.

  2. Reinstall the template. This is appropriate for both misconfigurations and security concerns, but you will lose all customizations.

  3. Full revert. This is appropriate for both misconfigurations and security concerns, and it can preserve your customizations. However, it is a bit more complex.

Root revert

Important: This command will roll back any changes made during the last time the TemplateVM was run, but not before. This means that if you have already restarted the TemplateVM, using this command is unlikely to help, and you’ll likely want to reinstall it from the repository instead. On the other hand, if the template is already broken or compromised, it won’t hurt to try reverting first. Just make sure to back up all of your data and changes first!

  1. Shut down <template>. If you’ve already just shut it down, do not start it again (see above).

  2. In a dom0 terminal:

     qvm-volume revert <template>:root
    

Reinstall the template

Please see How to Reinstall a TemplateVM.

Full revert

This is like the simple revert, except:

  • You must also revert the private volume with qvm-volume revert <template>:private. This requires you to have an old revision of the private volume, which does not exist with the current default config. However, if you don’t have anything important in the private volume (likely for a TemplateVM), then you can work around this by just resetting the private volume with qvm-volume import --no-resize <template>:private /dev/null.

  • The saved revision of the volumes must be uncompromised. With the default revisions_to_keep=1 for the root volume, you must not have started the template since the compromising action.

Temporarily allowing networking for software installation

Some third-party applications cannot be installed using the standard repositories and need to be manually downloaded and installed. When the installation requires internet connection to access third-party repositories, it will naturally fail when run in a Template VM because the default firewall rules for templates only allow connections from package managers. So it is necessary to modify firewall rules to allow less restrictive internet access for the time of the installation, if one really wants to install those applications into a template. As soon as software installation is completed, firewall rules should be returned back to the default state. The user should decide by themselves whether such third-party applications should be equally trusted as the ones that come from the standard Fedora signed repositories and whether their installation will not compromise the default Template VM, and potentially consider installing them into a separate template or a standalone VM (in which case the problem of limited networking access doesn’t apply by default), as described above.

Updates proxy

Updates proxy is a service which allows access only from package managers. This is meant to mitigate user errors (like using browser in the template VM), rather than some real isolation. It is done with http proxy (tinyproxy) instead of simple firewall rules because it is hard to list all the repository mirrors (and keep that list up to date). The proxy is used only to filter the traffic, not to cache anything.

The proxy is running in selected VMs (by default all the NetVMs (1)) and intercepts traffic directed to 10.137.255.254:8082. Thanks to such configuration all the VMs can use the same proxy address, and if there is a proxy on network path, it will handle the traffic (of course when firewall rules allow that). If the VM is configured to have access to the updates proxy (2), the startup scripts will automatically configure dnf to really use the proxy (3). Also access to updates proxy is independent of any other firewall settings (VM will have access to updates proxy, even if policy is set to block all the traffic).

There are two services (qvm-service, service framework):

  1. qubes-updates-proxy (and its deprecated name: qubes-yum-proxy) - a service providing a proxy for templates - by default enabled in NetVMs (especially: sys-net)
  2. updates-proxy-setup (and its deprecated name: yum-proxy-setup) - use a proxy provided by another VM (instead of downloading updates directly), enabled by default in all templates

Both the old and new names work. The defaults listed above are applied if the service is not explicitly listed in the services tab.

Technical details

The updates proxy uses RPC/qrexec. The proxy is configured in qrexec policy in dom0: /etc/qubes-rpc/policy/qubes.UpdatesProxy. By default this is set to sys-net and/or sys-whonix, depending on firstboot choices. This new design allows for templates to be updated even when they are not connected to any NetVM.

Example policy file in R4.0 (with Whonix installed, but not set as default UpdateVM for all templates):

# any VM with tag `whonix-updatevm` should use `sys-whonix`; this tag is added to `whonix-gw` and `whonix-ws` during installation and is preserved during template clone
@tag:whonix-updatevm @default allow,target=sys-whonix
@tag:whonix-updatevm @anyvm deny

# other templates use sys-net
@type:TemplateVM @default allow,target=sys-net
@anyvm @anyvm deny

Installing Snap Packages

Snap packages do not use the normal update channels for Debian and Fedora (apt and dnf) and are often installed as the user rather than as root. To support these in an AppVM you need to take the following steps:

  1. In the TemplateVM you must install snapd and qubes-snapd-helper: Open a terminal in TemplateVM and run:
[user@fedora-30-snap-demo ~]$ sudo dnf install snapd qubes-snapd-helper
Last metadata expiration check: 0:55:39 ago on Thu Nov 14 09:26:47 2019.
Dependencies resolved.
========================================================================================================
 Package                       Arch    Version                             Repository              Size
========================================================================================================
Installing:
 snapd                         x86_64  2.42.1-1.fc30                       updates                 17 M
 qubes-snapd-helper            noarch  1.0.1-1.fc30                        qubes-vm-r4.0-current   10 k
Installing dependencies:
[...]

Transaction Summary
========================================================================================================
Install  20 Packages

Total download size: 37 M
Installed size: 121 M
Is this ok [y/N]: y

Downloading Packages:
[..]
Failed to resolve booleanif statement at /var/lib/selinux/targeted/tmp/modules/200/snappy/cil:1174
/usr/sbin/semodule:  Failed!
[...]
Last metadata expiration check: 0:57:08 ago on Thu Nov 14 09:26:47 2019.
Notifying dom0 about installed applications

Installed:
  snapd-2.42.1-1.fc30.x86_64                                              qubes-snapd-helper-1.0.1-1.fc30.noarch                           
[...]                          
Complete!

You may see the following message:

Failed to resolve booleanif statement at /var/lib/selinux/targeted/tmp/modules/200/snappy/cil:1174
/usr/sbin/semodule:  Failed!

This is expected and you can safely continue.

Shutdown the TemplateVM:

[user@fedora-30-snap-demo ~]$ sudo shutdown -h now
  1. Now open the AppVM in which you would like to install the Snap application and run a terminal:
[user@snap-demo-AppVM ~]$ snap install <package>

When the install is complete you can close the terminal window.

  1. Refresh the Applications list for the AppVM. In the Qubes Menu for the AppVM* launch the Qube Settings. Then go to the Applications tab and click “Refresh Applications”

The refresh will take a few minutes; after it’s complete the Snap app will appear in the AppVM’s list of available applications. At this point the snap will be persistent within the AppVM and will receive updates when the AppVM is running.

Autostarting Installed Applications

If you want a desktop app to start automatically every time a qube starts you can create a link to it in the ~/.config/autostart directory of the AppVM. This might be useful for Qubes that you set to automatically start on boot or for Qubes that have a set of apps you typically use all day, such as a chat app.

  1. Open a terminal in the AppVM where you would like the app to launch.
  2. List the names of the available desktop shortcuts by running the command ls /usr/share/applications and find the exact name of the shortcut to the app you want to autostart:
[user@example-AppVM ~]$ ls /usr/share/applications/
bluetooth-sendto.desktop
eog.desktop
firefox.desktop
...
xterm.desktop
yelp.desktop
  1. Create the autostart directory:
[user@example-AppVM ~]$ mkdir -p ~/.config/autostart
  1. Make a link to the desktop app file you’d like to start in the autostart directory. For example, the command below will link the Thunderbird app into the autostart directory:
[user@example-AppVM ~]$ ln -s /usr/share/applications/mozilla-thunderbird.desktop ~/.config/autostart/mozilla-thunderbird.desktop

Note that the app will autostart only when the AppVM starts. If you would like the AppVM to autostart, select the “Start qube automatically on boot” checkbox in the AppVM’s Qube Settings.