Tag Archives: xen

Xen Project 4.5.2 Maintenance Release Available

I am pleased to announce the release of Xen 4.5.2. Xen Project Maintenance releases are released roughly every 4 months, in line with our Maintenance Release Policy. We recommend that all users of the 4.5 stable series update to this point release.

Xen 4.5.2 is available immediately from its git repository:

    xenbits.xenproject.org/gitweb/?p=xen.git;a=shortlog;h=refs/heads/stable-4.5
    (tag RELEASE-4.5.2)

or from the Xen Project download page at www.xenproject.org/downloads/xen-archives/xen-45-series/xen-452.html.

This release contains many bug fixes and improvements. For a complete list of changes in this release, please check lists of changes on the download page.

Will Docker Replace Virtual Machines?

Docker is certainly the most influential open source project of the moment. Why is Docker so successful? Is it going to replace Virtual Machines? Will there be a big switch? If so, when?

Let’s look at the past to understand the present and predict the future. Before virtual machines, system administrators used to provision physical boxes to their users. The process was cumbersome, not completely automated, and it took hours if not days. When something went wrong, they had to run to the server room to replace the physical box.

With the advent of virtual machines, DevOps could install any hypervisor on all their boxes, then they could simply provision new virtual machines upon request from their users. Provisioning a VM took minutes instead of hours and could be automated. The underlying hardware made less of a difference and was mostly commoditized. If one needed more resources, it would just create a new VM. If a physical machine broke, the admin just migrated or resumed her VMs onto a different host.

Finer-grained deployment models became viable and convenient. Users were not forced to run all their applications on the same box anymore, to exploit the underlying hardware capabilities to the fullest. One could run a VM with the database, another with middleware and a third with the webserver without worrying about hardware utilization. The people buying the hardware and the people architecting the software stack could work independently in the same company, without interference. The new interface between the two teams had become the virtual machine. Solution architects could cheaply deploy each application on a different VM, reducing their maintenance costs significantly. Software engineers loved it. This might have been the biggest innovation introduced by hypervisors.

A few years passed and everybody in the business got accustomed to working with virtual machines. Startups don’t even buy server hardware anymore, they just shop on Amazon AWS. One virtual machine per application is the standard way to deploy software stacks.

Application deployment hasn’t changed much since the ’90s though. Up until then, it still involved installing a Linux distro, mostly built for physical hardware, installing the required deb or rpm packages, and finally installing and configuring the application that one actually wanted to run.

In 2013 Docker came out with a simple, yet effective tool to create, distribute and deploy applications wrapped in a nice format to run in independent Linux containers. It comes with a registry that is like an app store for these applications, which I’ll call “cloud apps” for clarity. Deploying the Nginx webserver had just become one “docker pull nginx” away. This is much quicker and simpler than installing the latest Ubuntu LTS. Docker cloud apps come preconfigured and without any unnecessary packages that are unavoidably installed by Linux distros. In fact the Nginx Docker cloud app is produced and distributed by the Nginx community directly, rather than Canonical or Red Hat.

Docker’s outstanding innovations are the introduction of a standard format for cloud applications, including the registry. Instead of using VMs to run cloud apps, Linux containers are used instead. Containers had been available for years, but they weren’t quite popular outside Google and few other circles. Although they offer very good performance, they have fewer features and weaker isolation compared to virtual machines. As a rising star, Docker made Linux containers suddenly popular, but containers were not the reason behind Docker’s success. It was incidental.

What is the problem with containers? Their live-migration support is still very green and they cannot run non-native workloads (Windows on Linux or Linux on Windows). Furthermore, the primary challenge with containers is security: the surface of attack is far larger compared to virtual machines. In fact, multi-tenant container deployments are strongly discouraged by Docker, CoreOS, and anybody else in the industry. With virtual machines you don’t have to worry about who is going to use it or how it will be used. On the other hand, only containers that belong to the same user should be run on the same host. Amazon and Google offer container hosting, but they both run each container on top of a separate virtual machine for isolation and security. Maybe inefficient but certainly simple and effective.

People are starting to notice this. At the beginning of the year a few high profile projects launched to bring the benefits of virtual machines to Docker, in particular Clear Linux by Intel and Hyper. Both of them use conventional virtual machines to run Docker cloud applications directly (no Linux containers are involved). We did a few tests with Xen: tuning the hypervisor for this use case allowed us to reach the same startup times offered by Linux containers, retaining all the other features. A similar effort by Intel for Xen is being presented at the Xen Developer Summit and Hyper is also presenting their work.

This new direction has the potential to deliver the best of both worlds to our users: the convenience of Docker with the security of virtual machines. Soon Docker might not be fighting virtual machines at all, Docker could be the one deploying them.

A Chinese translation of the article is available here: http://dockone.io/article/598

Xen Project Hypervisor versions 4.3.4 and 4.4.2 are available

I am pleased to announce the release of Xen 4.3.4 and Xen 4.4.2. Both releases are available immediately from their git repositories and download pages (see below). We recommend to all users of the 4.3 and 4.4 stable series to update to these latest point releases.

Xen 4.3.4

This release is available immediately from its git repository at
http://xenbits.xen.org/gitweb/?p=xen.git;a=shortlog;h=refs/heads/stable-4.3
(tag RELEASE-4.3.4) or from the XenProject download page.

Note that this is expected to be the last release of the 4.3 stable series. The tree will be switched to security only maintenance mode after this release.

This fixes the following critical vulnerabilities:

  • CVE-2014-5146, CVE-2014-5149 / XSA-97: Long latency virtual-mmu operations are not preemptible
  • CVE-2014-7154 / XSA-104: Race condition in HVMOP_track_dirty_vram
  • CVE-2014-7155 / XSA-105: Missing privilege level checks in x86 HLT, LGDT, LIDT, and LMSW emulation
  • CVE-2014-7156 / XSA-106: Missing privilege level checks in x86 emulation of software interrupts
  • CVE-2014-7188 / XSA-108: Improper MSR range used for x2APIC emulation
  • CVE-2014-8594 / XSA-109: Insufficient restrictions on certain MMU update hypercalls
  • CVE-2014-8595 / XSA-110: Missing privilege level checks in x86 emulation of far branches
  • CVE-2014-8866 / XSA-111: Excessive checking in compatibility mode hypercall argument translation
  • CVE-2014-8867 / XSA-112: Insufficient bounding of “REP MOVS” to MMIO emulated inside the hypervisor
  • CVE-2014-9030 / XSA-113: Guest effectable page reference leak in MMU_MACHPHYS_UPDATE handling
  • CVE-2014-9065, CVE-2014-9066 / XSA-114: p2m lock starvation
  • CVE-2015-0361 / XSA-116: xen crash due to use after free on hvm guest teardown
  • CVE-2015-1563 / XSA-118: arm: vgic: incorrect rate limiting of guest triggered logging
  • CVE-2015-2152 / XSA-119: HVM qemu unexpectedly enabling emulated VGA graphics backends
  • CVE-2015-2044 / XSA-121: Information leak via internal x86 system device emulation
  • CVE-2015-2045 / XSA-122: Information leak through version information hypercall
  • CVE-2015-2151 / XSA-123: Hypervisor memory corruption due to x86 emulator flaw

Additionally a bug in the fix for CVE-2014-3969 / CVE-2015-2290 / XSA-98 (which got assigned CVE-2015-2290) got addressed.

Sadly the workaround for CVE-2013-3495 / XSA-59 (Intel VT-d Interrupt Remapping engines can be evaded by native NMI interrupts) still can’t be guaranteed to cover all affected chipsets; Intel continues to be working on providing us with a complete list.

Apart from those there are many further bug fixes and improvements.

We recommend all users of the 4.3 stable series to update to this last point release.

Xen 4.4.2

This release is available immediately from its git repository at
http://xenbits.xen.org/gitweb/?p=xen.git;a=shortlog;h=refs/heads/stable-4.4
(tag RELEASE-4.4.2) or from the XenProject download page.

This fixes the following critical vulnerabilities:

  • CVE-2014-5146, CVE-2014-5149 / XSA-97: Long latency virtual-mmu operations are not preemptible
  • CVE-2014-7154 / XSA-104: Race condition in HVMOP_track_dirty_vram
  • CVE-2014-7155 / XSA-105: Missing privilege level checks in x86 HLT, LGDT, LIDT, and LMSW emulation
  • CVE-2014-7156 / XSA-106: Missing privilege level checks in x86 emulation of software interrupts
  • CVE-2014-6268 / XSA-107: Mishandling of uninitialised FIFO-based event channel control blocks
  • CVE-2014-7188 / XSA-108: Improper MSR range used for x2APIC emulation
  • CVE-2014-8594 / XSA-109: Insufficient restrictions on certain MMU update hypercalls
  • CVE-2014-8595 / XSA-110: Missing privilege level checks in x86 emulation of far branches
  • CVE-2014-8866 / XSA-111: Excessive checking in compatibility mode hypercall argument translation
  • CVE-2014-8867 / XSA-112: Insufficient bounding of “REP MOVS” to MMIO emulated inside the hypervisor
  • CVE-2014-9030 / XSA-113: Guest effectable page reference leak in MMU_MACHPHYS_UPDATE handling
  • CVE-2014-9065, CVE-2014-9066 / XSA-114: p2m lock starvation
  • CVE-2015-0361 / XSA-116: xen crash due to use after free on hvm guest teardown
  • CVE-2015-1563 / XSA-118: arm: vgic: incorrect rate limiting of guest triggered logging
  • CVE-2015-2152 / XSA-119: HVM qemu unexpectedly enabling emulated VGA graphics backends
  • CVE-2015-2044 / XSA-121: Information leak via internal x86 system device emulation
  • CVE-2015-2045 / XSA-122: Information leak through version information hypercall
  • CVE-2015-2151 / XSA-123: Hypervisor memory corruption due to x86 emulator flaw

Additionally a bug in the fix for CVE-2014-3969 / CVE-2015-2290 / XSA-98 (which got assigned CVE-2015-2290) got addressed.

Sadly the workaround for CVE-2013-3495 / XSA-59 (Intel VT-d Interrupt Remapping engines can be evaded by native NMI interrupts) still can’t be guaranteed to cover all affected chipsets; Intel continues to be working on providing us with a complete list.

Apart from those there are many further bug fixes and improvements.

We recommend all users of the 4.4 stable series to update to this first point release.

Xen.org at LinuxWorld (August 5 – 7)

The Xen.org community will have a booth  (#210) at the joint LinuxWorld / Next Generation Data Center event held in San Francisco, August 5- 7 at the Moscone Center. The booth will be staffed by myself as well as community members with spare time during the event.  If you are planning on attending this event and would like to help please let me know. I will be creating a schedule for community members later this year as we get closer to August.