[Bug 1927519] Re: Mitigate libvirt: error : unable to set AppArmor profile 'libvirt-<vm-uuid>' for '/usr/bin/kvm-spice': No such file or directory

[Łukasz Zemczak]

Hello Ioanna, or anyone else affected,

Accepted libvirt into impish-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/libvirt/7.6.0-0ubuntu1.1 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
impish to verification-done-impish. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-impish. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: libvirt (Ubuntu Impish)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-impish

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https://bugs.launchpad.net/bugs/1927519

Title:
  Mitigate libvirt: error : unable to set AppArmor profile 'libvirt-<vm-
  uuid>' for '/usr/bin/kvm-spice': No such file or directory

Status in Ubuntu Cloud Archive:
  New
Status in Ubuntu Cloud Archive queens series:
  New
Status in Ubuntu Cloud Archive stein series:
  New
Status in Ubuntu Cloud Archive ussuri series:
  New
Status in libvirt package in Ubuntu:
  Fix Committed
Status in libvirt source package in Bionic:
  In Progress
Status in libvirt source package in Focal:
  In Progress
Status in libvirt source package in Hirsute:
  In Progress
Status in libvirt source package in Impish:
  Fix Committed
Status in libvirt source package in Jammy:
  Fix Committed

Bug description:
  [Impact]

  Some times libvirt fails to start a vm with the following error :
  libvirt:  error : unable to set AppArmor profile 'libvirt-b05b297f-952f-42d6-b04e-f9a13767db54' for '/usr/bin/kvm-spice': No such file or directory

  This happens because for some reason the apparmor profile for the
  guest /etc/apparmor.d/libvirt/libvirt-<vm-uuid> has 0 size.

  We do not now why the above file gets truncated to begin with and
  therefore we do not know the root cause to fix it there. But the
  condition is easy to detect and 100% broken, so we can detect and
  recreate the file in those cases.

  [Test case]

  To reproduce this behaviour, create a vm and stop it, note the uuid.

  For example:
  $ uvt-simplestreams-libvirt --verbose sync --source http://cloud-images.ubuntu.com/daily arch=amd64 label=daily release=focal
  $ uvt-kvm create --password=ubuntu f release=focal arch=amd64 label=daily
  $ virsh dominfo f
  ...
  Security label: libvirt-1ceac8db-c1e9-40b2-8ada-a60349454fc1 (enforcing)
  $ virsh shutdown f

  Then make the start apparmor profile an empty file.
  On Bionic/Focal that file will be non-existant by default (cleaned on guest stop), on Hirsute/Impish it will be around for admin-edit but with content. Therefore "touch" isn't enough every time, instead really put nothing to it as that is how the real issue looks like).

  $ cat /dev/null | sudo tee /etc/apparmor.d/libvirt/libvirt-1ceac8db-c1e9-40b2-8ada-a60349454fc1
  # ensure it is size zero
  $ ll /etc/apparmor.d/libvirt/libvirt-1ceac8db-c1e9-40b2-8ada-a60349454fc1
  -rw-r--r-- 1 root root 0 Nov 18 09:01 /etc/apparmor.d/libvirt/libvirt-1ceac8db-c1e9-40b2-8ada-a60349454fc1

  Next try to start the vm, it will try to use the file it found
  (instead of creating a new one as it would when non-existing) and will
  fail doing so:

  $ virsh start f
  error: internal error: Process exited prior to exec: libvirt:  error : unable to set AppArmor profile 'libvirt-1ceac8db-c1e9-40b2-8ada-a60349454fc1' for '/usr/bin/qemu-system-x86_64': No such file or directory

  To manually be able to start the vm again just delete the libvirt-<vm-uuid> file.
  With the fix applied libvirt will recreate the file and guest start works again.

  
  In addition (independent to the case) I'll run a set of common regression tests against <release>-proposed which didn't run for a while and would make us also spot if anything other slipped in from different places (like the dwarves hiccup we had). Since testing shall be on "the real build" and resources are limited I'd this time do so only on the builds in proposed.

  [Regression Potential]

  The new code is only active when the size of the file is zero which is
  a 100% guarantee that the guest is broken and won't start.
  Nevertheless if we made a mistake in the fix the area (of the many
  things libvirt does) to look at is the generating and usage of
  apparmor profiles.

  [Other]

  Similar reported bug : https://bugs.debian.org/cgi-
  bin/bugreport.cgi?bug=890084

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