** Tags added: kernel-da-key

** Changed in: linux (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/1684481

Title:
  KVM guest execution start apparmor blocks on /dev/ptmx now
  (regression?)

Status in apparmor package in Ubuntu:
  New
Status in linux package in Ubuntu:
  Incomplete
Status in lxd package in Ubuntu:
  New

Bug description:
  Setup:
  - Xenial host
  - lxd guests with Trusty, Xenial, ...
  - add a LXD profile to allow kvm [3] (inspired by stgraber)
  - spawn KVM guests in the LXD guests using the different distro release 
versions
  - guests are based on the uvtool default template which has a serial console 
[4]

  Issue:
  - guest starting with serial device gets blocked by apparmor and killed on 
creation
  - This affects at least ppc64el and x86 (s390x has no serial concept that 
would match)
  - This appeared in our usual checks on -proposed releases so maybe we 
can/should stop something?
    Last good was "Apr 5, 2017 10:40:50 AM" first bad one "Apr 8, 2017 5:11:22 
AM"

  Background:
  We use this setup for a while and it was working without a change on our end.
  Also the fact that it still works in the Trusty LXD makes it somewhat 
suspicious.
  Therefore I'd assume an SRUed change in LXD/Kernel/Apparmor might be the 
reason and open this bug to get your opinion on it.

  You can look into [1] and search for uvt-kvm create in it.

  Deny in dmesg:
  [652759.606218] audit: type=1400 audit(1492671353.134:4520): 
apparmor="DENIED" operation="open" 
namespace="root//lxd-testkvm-xenial-from_<var-lib-lxd>" 
profile="libvirt-668e21f1-fa55-4a30-b325-0ed5cfd55e5b" name="/dev/pts/ptmx" 
pid=27162 comm="qemu-system-ppc" requested_mask="wr" denied_mask="wr" fsuid=0 
ouid=0

  Qemu-log:
  2017-04-20T06:55:53.139450Z qemu-system-ppc64: -chardev pty,id=charserial0: 
Failed to create PTY: No such file or directory

  There was a similar issue on qmeu namespacing (which we don't use on any of 
these releases) [2].
  While we surely don't have the "same" issue the debugging on the namespacing 
might be worth as it could be related.

  Workaround for now:
  - drop serial section from guest xml

  [1]: 
https://jenkins.ubuntu.com/server/view/Virt/job/virt-migration-cross-release-amd64/78/consoleFull
  [2]: https://bugzilla.redhat.com/show_bug.cgi?id=1421036
  [3]: 
https://git.launchpad.net/~ubuntu-server/ubuntu/+source/qemu-migration-test/tree/kvm_profile.yaml
  [4]: https://libvirt.org/formatdomain.html#elementsCharPTY

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