group.of.nepali.translators team mailing list archive

[Launchpad Bug Tracker <1910835@xxxxxxxxxxxxxxxxxx>]

This bug was fixed in the package cloud-init - 20.4-0ubuntu1~20.10.2

---------------
cloud-init (20.4-0ubuntu1~20.10.2) groovy; urgency=medium

  * cherry-pick 4f62ae8d: Fix regression with handling of IMDS ssh keys
    (#760) (LP: #1910835)

 -- Daniel Watkins <oddbloke@xxxxxxxxxx>  Mon, 11 Jan 2021 17:10:13
-0500

** Changed in: cloud-init (Ubuntu Groovy)
       Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of नेपाली
भाषा समायोजकहरुको समूह, which is subscribed to Xenial.
Matching subscriptions: Ubuntu 16.04 Bugs
https://bugs.launchpad.net/bugs/1910835

Title:
  Azure IMDS publicKeys contain \r\n which prevents ssh access to vms
  using cloud-generated ssh keys.

Status in cloud-init:
  Confirmed
Status in cloud-init package in Ubuntu:
  Fix Released
Status in cloud-init source package in Xenial:
  Fix Released
Status in cloud-init source package in Bionic:
  Fix Released
Status in cloud-init source package in Focal:
  Fix Released
Status in cloud-init source package in Groovy:
  Fix Released
Status in cloud-init source package in Hirsute:
  Fix Released

Bug description:
  == Begin SRU Template ==
  [Impact]
  The previous version of cloud-init used OpenSSL to process the SSH keys provided by the Azure platform.  cloud-init 20.4 replaced that code with a more efficient implementation, but one which did not use OpenSSL: this meant that users passing certificates to instances, or users generating SSH keys in Azure's web UI (which inserts \r\n sequences into the public key content), were regressed: their certificates and malformed SSH keys were no longer handled, so they could fail to gain access to newly-launched instances.

  This release is only a single functional cherry-pick which solely
  affects Azure platform. It is a critical bug we wish to release as
  soon as possible

    * Azure: cherry-pick 4f62ae8d: Fix regression with handling of IMDS ssh keys
      (#760) (LP: #1910835)

  The functional changeset here introduces a raise KeyError exception
  which forces cloud-init to revert to previous released logic of the
  previous cloud-init public release 20.3.

  [Test Case]

  As this is a single commit backport, the cloud-init SRU exception need
  not apply.  An upstream integration test has been written for this
  issue (https://github.com/canonical/cloud-
  init/blob/master/tests/integration_tests/bugs/test_lp1910835.py).

  A full run of the upstream test suite on Azure will therefore
  regression test the update generally and test this issue specifically:
  a log of a test run for each suite will be attached.

  [Regression Potential]

  The proposed change only modifies code paths used on Azure,
  specifically to revert to a previous behaviour: users unaffected by
  the bug should see no change (their keys will get to their instance
  via a different route), and users affected by the bug would have been
  unable to access their instances before (so cannot be relying on this
  behaviour in a way which we could break by fixing it).

  [Discussion]
  This should only affect public Azure VM launched which use Azure to --generate-ssh-keys either from the dashboard or from the `az cli`

  Any other cloud-platform is not affected by this change.

  == End SRU Template ==

    * cherry-pick 4f62ae8d: Fix regression with handling of IMDS ssh keys
      (#760) (LP: #1910835)

  == Original Description ==

  cloud-init 20.4 or later will incorrectly add Azure publicKeys to
  .ssh/authorized_keys preventing ssh access for cloud-generated keys.

  To reproduce: launch an ubuntu VM from the portal.azure.com  choosing
  to generate new ssh key.

  When the instance is launched you can see that the ssh-rsa content
  provided in the metadata publicKeys value  contains CRLF characters
  (\r\n) thus splitting the content of the pubkey onto multiple lines
  when it is rendered into .ssh/authorized_keys.

  the solution is either for IMDS to stop adding the CRLF characters or
  cloud-init to strip them out.

  Here is the IMDS value provided to cloud-init

  cloud-init query --format '{{ds.meta_data.imds.compute.publicKeys}}'

  [{'keyData': 'ssh-rsa
  AAAAB3NzaC1yc2EAAAADAQABAAABgQCllNnyHXFWlMb9EKD9LZrOxt1d\r\nk/QxYwQ0HYEP8n6TUWoUsN3mv/Qk/qWH76Pa6f33hefzTFRiom7Ls/tJMcr/ki8R\r\n9FqyYOu0xxHmpXTUWFoZQCZtGRMtvDl/s76Wr1sCsE/ez+EcAPeGGm/B7jHtDAUW\r\nlkINfuPVBDfRtSfmnlCKS+sIf1XOqvRASGWi05zAW921T4OkiattyXyhaOimJOwq\r\n4jAXmydwtNCN2iGGKWS8YeXbtgveReqZVVKtcDKevgWdNyqZa69uq9tRujobjCh7\r\n6xxCkQcdCLospgqX79GBbdRys6mVxVgc349RIWjQwglRQpJwNzkeOG5Q+La2MEhu\r\niKqKJMvYVhil3khzMuZwzmTrGbRx0E8AS+Cm064RBgbcdjCW8dDYGLuk2eQ2v9Ht\r\n6eERfxMBNg3udv1jmiKpjjHIg99HDU4VqhL3aHmg+TSrxByd0cAgFBV+H0CiUVC9\r\nS2mLJ6Peu/HDwd88E8Wqiv3eAsjcaCRH3QiQVaU=
  generated-by-azure\r\n', 'path': '/home/ubuntu/.ssh/authorized_keys'}]

  cloud-init  renders this directly to .ssh/authorized_keys without
  processing the string, resulting in an invalid keyline:

  ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQCllNnyHXFWlMb9EKD9LZrOxt1d k/QxYwQ0HYEP8n6TUWoUsN3mv/Qk/qWH76Pa6f33hefzTFRiom7Ls/tJMcr/ki8R^M
  9FqyYOu0xxHmpXTUWFoZQCZtGRMtvDl/s76Wr1sCsE/ez+EcAPeGGm/B7jHtDAUW^M
  lkINfuPVBDfRtSfmnlCKS+sIf1XOqvRASGWi05zAW921T4OkiattyXyhaOimJOwq^M
  4jAXmydwtNCN2iGGKWS8YeXbtgveReqZVVKtcDKevgWdNyqZa69uq9tRujobjCh7^M
  6xxCkQcdCLospgqX79GBbdRys6mVxVgc349RIWjQwglRQpJwNzkeOG5Q+La2MEhu^M
  iKqKJMvYVhil3khzMuZwzmTrGbRx0E8AS+Cm064RBgbcdjCW8dDYGLuk2eQ2v9Ht^M
  6eERfxMBNg3udv1jmiKpjjHIg99HDU4VqhL3aHmg+TSrxByd0cAgFBV+H0CiUVC9^M
  S2mLJ6Peu/HDwd88E8Wqiv3eAsjcaCRH3QiQVaU= generated-by-azure

  this prevents ssh from actually reading the right key from azure:

  $ ssh-keygen -lf /home/ubuntu/.ssh/authorized_keys

  If we strip the CRLF (^M) characters and reparse with ssh-keygenm we
  see the proper key registered:

  $ ssh-keygen -lf /home/ubuntu/.ssh/authorized_keys
  3072 SHA256:PQ9EKxTKONJKFC2N56UpL6+Oc/cujfA9HpsF5VW2QDI generated-by-azure (RSA)

  If cloud-init (or IMDS) were to strip those \r\n characters from each
  line ssh

To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-init/+bug/1910835/+subscriptions