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

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. Fortunately, it’s easy to revert changes to TemplateVMs using the command appropriate to your version of Qubes.

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!

For example, to revert changes to the fedora-XX TemplateVM (where XX is your Fedora version):

  1. Shut down fedora-XX. If you’ve already just shut it down, do not start it again (see above).
  2. In a dom0 terminal, type:

     qvm-volume revert fedora-XX:root
    

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

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 on 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