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Posts tagged with '14.04'

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Ubuntu updates for TCP SACK Panic vulnerabilities

Issues have been identified in the way the Linux kernel’s TCP implementation processes Selective Acknowledgement (SACK) options and handles low Maximum Segment Size (MSS) values. These TCP SACK Panic vulnerabilities could expose servers to a denial of service attack, so it is crucial to have systems patched.

Updated versions of the Linux kernel packages are being published as part of the standard Ubuntu security maintenance of Ubuntu releases 16.04 LTS, 18.04 LTS, 18.10, 19.04 and as part of the extended security maintenance for Ubuntu 14.04 ESM users.

It is recommended to update to the latest kernel packages and consult Ubuntu Security Notices for further updates.

Ubuntu Advantage for Infrastructure subscription customers can find the latest status information in our Knowledge Base and file a support case with Canonical support for any additional questions or concerns around SACK Panic.

Canonical’s Kernel Livepatch updates for security vulnerabilities related to TCP SACK processing in the Linux kernel have been released and are described by CVEs 2019-11477 and 2019-11478, with details of the patch available in LSN-0052-1.

These CVEs have a Livepatch fix available, however, a minimum kernel version is required for Livepatch to install the fix as denoted by the table in LSN-0052-1, reproduced here:

| Kernel                   | Version | flavors           |
|--------------------------+----------+--------------------------|
| 4.4.0-148.174            | 52.3 | generic, lowlatency      |
| 4.4.0-150.176            | 52.3 | generic, lowlatency      |
| 4.15.0-50.54             | 52.3 | generic, lowlatency      |
| 4.15.0-50.54~16.04.1     | 52.3 | generic, lowlatency      |
| 4.15.0-51.55             | 52.3 | generic, lowlatency      |
| 4.15.0-51.55~16.04.1     | 52.3 | generic, lowlatency      |

Livepatch fixes for CVEs 2019-11477 and 2019-11478 are not available for prior kernels, and an upgrade and reboot to the appropriate minimum version is necessary. These kernel versions correspond to the availability of mitigations for the MDS series of CVEs (CVE-2018-12126, CVE-2018-12127, CVE-2018-12130 and CVE-2019-11091).

Additionally, a third SACK related issue, CVE-2019-11479, does not have a Livepatch fix available because it is not technically feasible to apply the changes via Livepatch. Mitigation information is available at the Ubuntu Security Team Wiki.

If you have any questions and want to learn more about these patches, please do not hesitate to get in touch.

The post Ubuntu updates for TCP SACK Panic vulnerabilities appeared first on Ubuntu Blog.

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Ben Howard

With Ubuntu 12.04.2, the kernel team introduced the idea of the "hardware enablement kernel" (HWE), originally intended to support new hardware for bare metal server and desktop. In fact, the documentation indicates that HWE images are not suitable for Virtual or Cloud Computing environments.  The thought was that cloud and virtual environments provide stable hardware and that the newer kernel features would not be needed.

Time has proven this assumption painfully wrong. Take for example the need for drivers in virtual environments. Several of the Cloud providers that we have engaged with have requested the use of the HWE kernel by default. On GCE, the HWE kernels provide support for their NVME disks or multiqueue NIC support. Azure has benefited from having an updated HyperV driver stack resulting in better performance. When we engaged with VMware Air, the 12.04 kernel lacked the necessary drivers.

Perhaps more germane to our Cloud users is that containers are using kernel features. 12.04 users need to use the HWE kernel in order to make use of Docker. The new Ubuntu Fan project will be enabled for 14.04 via the HWE-V kernel for Ubuntu 14.04.3. If you use Ubuntu as your container host, you will likely consider using an HWE kernel.

And with that there has been a steady chorus of people requesting that we provide HWE image builds for AWS. The problem has never been the base builds; building the base bits is fairly easy. The hard part is that by adding base builds, each daily and release build goes form 96 images for AWS to 288 (needless to say that is quite a problem). Over the last few weeks -- largely in my spare time -- I've been working out what it would take to deliver HWE images for AWS.

I am happy to announce that as of today, we are now building HWE-U (3.16) and HWE-V (3.19) Ubuntu 14.04 images for AWS. To be clear, we are not making any behavioral changes to the standard Ubuntu 14.04 images. Unless users opt into using an HWE image on AWS they will continue to get the 3.13 kernel. However, for those who want newer kernels, they now have the choice.

For the time being, only amd64 and i386 builds are being published.. Over the next few weeks, we expect the HWE images to reach full feature parity including release promotions, and indexing. And I fully expect that the HWE-V version of 14.04 will include our recent Fan project once the SRU's complete.

Check them out at http://cloud-images.ubuntu.com/trusty/current/hwe-u and http://cloud-images.ubuntu.com/trusty/current/hwe-v .

As always, feedback is always welcome.

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Ben Howard

A few years ago when our fine friends on the kernel team introduced the idea of the "hardware enablement" (HWE) kernel, those of us in the Cloud world looked at it as curiosity. We thought that by in large, the HWE kernel would not be needed or wanted for Virtual Cloud instances.

And we were wrong.

So wrong in fact, that the HWE kernel has found its way into the Vagrant Cloud Images, VMware's vCHS, and Google's Compute engine as the default kernel for the Certified Images. The main reason for these requests is that virtual hardware moves at a fairly quick pace. Unlike traditional hardware, Virtual Hardware can be fixed and patched at the speed that software can be deployed.

The feedback in regards to Azure has been the same: users and Microsoft has asked for the HWE kernel consistently. Microsoft has validated that the HWE kernel (3.16) running Ubuntu 14.04 on Windows Azures passes their validation testing. In our testing, we have validated that the 3.16 kernel works quite well in Azure.

For Azure users, using the 3.16 HWE kernel brings SMB 2.1 copy file support and updates LIS drivers.

Therefore, starting with the latest Windows Azure image [1], all the Ubuntu 14.04 images will track the latest hardware enablement kernel. That means that all the goodness in Ubuntu 14.10's kernel will be the default for 14.04 users launching our official images on Windows Azure.

If you want to install the LTS kernel on your existing instance(s), simply run:

  • sudo apt-get update
  • sudo apt-get install linux-image-virtual-lts-utopic linux-lts-utopic-cloud-tools-common walinuxagent
  • sudo reboot


[1] b39f27a8b8c64d52b05eac6a62ebad85__Ubuntu-14_04_1-LTS-amd64-server-20150123-en-us-30GB

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Ben Howard

We are pleased to announce that Ubuntu 12.04 LTS, 14.04 LTS, and 14.10 are now in beta on Google Compute Engine [1, 2, 3].

These images support both the traditional user-data as well the Google Compute Engine startup scripts. We have included the Google Cloud SDK, pre-installed as well. Users coming from other Clouds can expect to have the same great experience as on other clouds, while enjoying the features of Google Compute Engine.

From an engineering perspective, a lot of us are excited to see this launch. While we don't expect too many rough edges, it is a beta, so feedback is welcome. Please file bugs or join us in #ubuntu-server on Freenode to report any issues (ping me, utlemming, rcj or Odd_Bloke).

Finally, I wanted to thank those that have helped on this project. Launching a cloud is not an easy engineering task. You have have build infrastructure to support the new cloud, create tooling to build and publish, write QA stacks, and do packaging work. All of this spans multiple teams and disciplines. The support from Google and Canonical's Foundations and Kernel teams have been instrumental in this launch, as well the engineers on the Certified Public Cloud team.

Getting the Google Cloud SDK:

As part of the launch, Canonical and Google have been working together on packaging a version of the Google Cloud SDK. At this time, we are unable to bring it into the main archives. However, you can find it in our partner archive.

To install it run the following:

  • echo "deb http://archive.canonical.com/ubuntu $(lsb_release -c -s) partner" | sudo tee /etc/apt/sources.list.d/partner.list
  • sudo apt-get update
  • sudo apt-get -y install google-cloud-sdk


Then follow the instruction for using the Cloud SDK at [4]


[1] https://cloud.google.com/compute/docs/operating-systems#ubuntu
[2] http://googlecloudplatform.blogspot.co.uk/2014/11/curated-ubuntu-images-now-available-on.html
[3] http://insights.ubuntu.com/2014/11/03/certified-ubuntu-images-available-on-google-cloud-platform/
[4] https://cloud.google.com/sdk/gcloud/

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Ben Howard

Cloud Images and Bash Vulnerabilities

The Ubuntu Cloud Image team has been monitoring the bash vulnerabilities. Due to the scope, impact and high profile nature of these vulnerabilties, we have published new images. New cloud images to address the lastest bash USN-2364-1 [1, 8, 9] are being released with a build serials of 20140927. These images include code to address all prior CVEs, including CVE-2014-6271 [6] and CVE-2014-7169 [7], and supersede images published in the past week which addressed those CVEs.

Please note: Securing Ubuntu Cloud Images requires users to regularly apply updates[5]; using the latest Cloud Images are insufficient. 

Addressing the full scope of the Bash vulnerability has been an iterative process. The security team has worked with the upstream bash community to address multiple aspects of the bash issue. As these fixes have become available, the Cloud Image team has published daily[2]. New released images[3] have been made available at the request of the Ubuntu Security team.

Canonical has been in contact with our public Cloud Partners to make these new builds available as soon as possible.

Cloud image update timeline

Daily image builds are automatically triggered when new package versions become available in the public archives. New releases for Cloud Images are triggered automatically when a new kernel becomes available. The Cloud Image team will manually trigger new released images when either requested by the Ubuntu Security team or when a significant defect requires.

Please note:  Securing Ubuntu cloud images requires that security updates be applied regularly [5], using the latest available cloud image is not sufficient in itself.  Cloud Images are built only after updated packages are made available in the public archives. Since it takes time to build the  images, test/QA and finally promote the images, there is time (sometimes  considerable) between public availablity of the package and updated Cloud Images. Users should consider this timing in their update strategy.

[1] http://www.ubuntu.com/usn/usn-2364-1/
[2] http://cloud-images.ubuntu.com/daily/server/
[3] http://cloud-images.ubuntu.com/releases/
[4] https://help.ubuntu.com/community/Repositories/Ubuntu/
[5] https://wiki.ubuntu.com/Security/Upgrades/
[6] http://people.canonical.com/~ubuntu-security/cve/2014/CVE-2014-6271.html
[7] http://people.canonical.com/~ubuntu-security/cve/2014/CVE-2014-7169.html
[8] http://people.canonical.com/~ubuntu-security/cve/2014/CVE-2014-7187.html
[9] http://people.canonical.com/~ubuntu-security/cve/2014/CVE-2014-7186.html

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