By Bryan Jacobson, Linux Technology Center.

While Virtualization offers many benefits, there can also be increased security risks. For example, consider a system running two hundred virtual images. All two hundred images are at risk if a flaw in the hypervisor (or configuration) allows any virtual guest to “break out” into the host environment and affect other virtual guests. sVirt is a project to improve the security of Linux virtualization. Svirt applies the Mandatory Access Control (MAC) features of SELinux to strengthen the isolation between virtual images. Svirt works with KVM/QEMU and other Linux virtualization systems where the virtual image runs as a Linux user space process.

sVirt is a community project, with founding authors from Red Hat: Daniel Berrange, James Morris, and Dan Walsh. sVirt is integrated with libvirt.

One of my favorite sVirt use cases is: “Strongly isolating desktop applications by running them in separately labeled VMs (e.g. online banking in one VM and World of Warcraft in another; opening untrusted office documents in an isolated VM for view/print only).” (From the 8/11/2008 sVirt project announcement at

The project announcement also identifies an excellent design goal: “Initially, sVirt should “just work” as a means to isolate VMs, with minimal administrative interaction. e.g. an option is added to virt-manager which allows a VM to be designated as “isolated”, and from then on, it is automatically run in a separate security context, with policy etc. being generated and managed by libvirt.”.

You can find a 48 minute video of James Morris’s February 2009 presentation on sVirt at

Slides from that presentation are at: