Video Podcast / TechSNAP (#190) hosted by Chris Las and Allan Jude is an interesting video podcast about a 2006 feature within VMWare's v-Sphere that gives the company a competitive edge in the virtualization world, Transparent Page Sharing (TPS), that is such a serious flaw the solution is to disable the service.
The hosts’ main focus of conversion stemmed from a blog from v-Sphere Land titled, “Why the VMWare vSphere TPS Vulnerability Is a Big Deal”. Transparent Page Sharing (TPS) is a feature that could potentially allow Virtual Machines to access the memory pages of other Virtual Machines running on a host computer, therefore, information may be compromised. This goes against the grain of virtual computing, virtual machines not being totally separated from one another.
Here is a brief window explanation of how VMWare uses Virtual Machines. Hypervisor is a program that allows guest multiple operating systems (Virtual Machines) to share the hardware a host computer. It controls/manages the host processor and resources, allocating what is needed to the virtual machines. With transparent page sharing, the hypervisor can reclaim the redundant copies and keep only one copy, which is shared by multiple virtual machines in the host’s physical memory. As a result, the total virtual machine host memory consumption is reduced and a higher level of memory overcommitment is possible. Overcommitment in the VMWare world means to benefit from more memory in the virtual arena than is physically available on a host computer.
The hosts’ poked fun at how VMWare downplayed the issue. Allan recited in a mocking fashion that VMWare states that “it only matters in certain cases” and also pointed out that VMWare defends its position generally by stating that “an academic paper said that this may be a problem, so we are turning it off”. In fact all new versions of ESX by default will come it off, current versions of ESX will have patches available for a fix and support will be offered by VMWare on how to disable the Transparent Page Sharing (TPS) feature on a host.
In conclusion, I find it fascinating that a research paper exposed this vulnerability recently, when the Transparent Page Sharing (TPS) feature came out back in 2006. It makes me wonder if VMWare will lose some of its market share to Microsoft’s Hyper-V as an answer to server density, because of loss of its major selling point combined with how it publically handled itself. I must confess that it is easy to lose sight of the fact that Virtual Machines do have a factor of vulnerability, because they are software based. Will VMWare be able to optimize its Transparent Page Sharing (TPS) feature in the future of abandon it?
