[Bug 1665698] Fix included in openstack/nova 15.0.3

OpenStack Infra 1665698 at bugs.launchpad.net
Wed Apr 12 18:55:11 UTC 2017


This issue was fixed in the openstack/nova 15.0.3 release.

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https://bugs.launchpad.net/bugs/1665698

Title:
  /etc/qemu-ifup not allowed by apparmor

Status in Ubuntu Cloud Archive:
  Invalid
Status in Ubuntu Cloud Archive newton series:
  Fix Released
Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) newton series:
  In Progress
Status in OpenStack Compute (nova) ocata series:
  Fix Committed
Status in libvirt package in Ubuntu:
  Fix Released
Status in nova package in Ubuntu:
  Invalid
Status in libvirt source package in Yakkety:
  Fix Committed
Status in nova source package in Yakkety:
  Fix Released

Bug description:
  SRU - Nova
  [Impact]
  OpenStack deployments using vif types `tap`, `ivs`, `iovisor`, `midonet`, and `vrouter` are unable to boot instances using libvirt 1.3.1 from Ubuntu 16.04 (as used by the Newton Ubuntu Cloud Archive). Note that this impacts the nova package which is currently in yakkety-proposed/newton-proposed - the version in *-updates does not have this issue.

  [Test case]
  Using an OpenStack cloud deployed with one of the above SDN's boot an instance.
  The instance will fail to boot with a libvirt error.
  Note cloud must be deployed using the -proposed packages from the Newton UCA.

  [Regression Potential]
  Minimal - the patch restores the previous behaviour for older libvirt versions, ensuring compatibility with documented libvirt version baselines in OpenStack Nova.

  ---

  SRU - libvirt
  [Impact]

   * Please do note that this SRU statement is about the libvirt portion
     of it, this is a fix of essentially an API break from Xenial to
     Yakkety. This is independent to any decision to the Openstack context
     discussion about the change to drop specifying a path at all.

   * Before 9c17d665fdc5f (v1.3.2 which means 1.3.1 in Xenial for us) it
     was possible to have the following interface configuration:
         <interface type='ethernet'/>
           <script path=''/>
         </interface>
     This resulted in -netdev tap,script=,.. Fortunately, qemu helped
     us to get away with this as it just ignored the empty script
     path. However, after the commit mentioned above it's libvirtd
     who is executing the script. Unfortunately without special
     case-ing empty script path.

   * The fix adds the special casing that qemu had into libvirts handling
     of the interface definition.

  [Test Case]

   * That is tricky as the way openstack is using to shove that in
     seems to not care on xml validation as much as e.g. virsh.
     If normally adding a device like
         <interface type='ethernet'>
           <script path=''/>
           <model type='virtio'/>
         </interface>
     At least in xenial AND yakkety blocked by the XML validation.
     But if trying to work around like with path='""'
     this gives "-netdev tap,script="",id=hostnet1" on yakkety then
     the fix does not apply as this is '""' and not ''.
     So to add the above snippet you have to edit it in via --skip-
     validate like
     $ virsh edit --skip-validate zesty-on-x-test
     This on older libvrit gave: -netdev tap,script=,id=hostnet1
     Which qemu understood as nop. But newer libvirt refuses.

   * Error:
     error: Failed to start domain <name>
     error: Cannot find '' in path: No such file or directory

   * Expected:
     Starting the domain as-is without calling a script,
     but also without complaining about being empty.

  [Regression Potential]

   * Regression should be low because of:
     * The fix is upstream for a while now without follow on fix
     * We are essentially going back to how it was
     * There is no case like "I had '' set in my setup but now it is
       a no-op which makes me fail" because if one had '' it failed until
       now.
   * Fix is in zesty for a few days without new fallout being reported
   * also it passed several levels of testing (on the case and general
     regression testing)
   * Due to extra xml checks a device like path='' is not even definable.
     So only those who run --skip-validate or similar are affected in
     the first place.

  [Other Info]

   * n/a

  ----

  I have VMs failing to start with 2017-02-17 15:38:44.458 264015 ERROR
  nova.compute.manager [instance: 0c97ab16-2d30-43fa-b0e4-a064a842b5ed]
  libvirtError: internal error: process exited while connecting to
  monitor: 2017-02-17T15:38:43.907222Z qemu-system-x86_64: -netdev
  tap,ifname=tapf34ef99e-18,id=hostnet0,vhost=on,vhostfd=28: network
  script /etc/qemu-ifup failed with status 256

  Log excerpt:
  http://cdn.pasteraw.com/b3tw4cjefomfi3e9k09hvodrfun85z

  Seems to be that /etc/qemu-ifup is being blocked by apparmor:
  type=AVC msg=audit(1487347189.015:28536): apparmor="DENIED" operation="exec" profile="libvirt-4a03fea7-e966-48e4-80ac-aa138db67243" name="/etc/qemu-ifup" pid=285438 comm="qemu-system-x86" requested_mask="x" denied_mask="x" fsuid=0 ouid=0
  type=PATH msg=audit(1487347189.015:28536): item=0 name="/etc/qemu-ifup" inode=66403 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 nametype=NORMAL

  root at ubuntu-trusty-5773:/etc/apparmor.d/abstractions# cat /etc/apparmor.d/libvirt/libvirt-4a03fea7-e966-48e4-80ac-aa138db67243
  #
  # This profile is for the domain whose UUID matches this file.
  #

  #include <tunables/global>

  profile libvirt-4a03fea7-e966-48e4-80ac-aa138db67243 {
    #include <abstractions/libvirt-qemu>
    #include <libvirt/libvirt-4a03fea7-e966-48e4-80ac-aa138db67243.files>

  }
  root at ubuntu-trusty-5773:/etc/apparmor.d/abstractions# cat /etc/apparmor.d/libvirt/libvirt-4a03fea7-e966-48e4-80ac-aa138db67243.files
  # DO NOT EDIT THIS FILE DIRECTLY. IT IS MANAGED BY LIBVIRT.
    "/var/log/libvirt/**/instance-00000008.log" w,
    "/var/lib/libvirt/qemu/domain-instance-00000008/monitor.sock" rw,
    "/var/run/libvirt/**/instance-00000008.pid" rwk,
    "/run/libvirt/**/instance-00000008.pid" rwk,
    "/var/run/libvirt/**/*.tunnelmigrate.dest.instance-00000008" rw,
    "/run/libvirt/**/*.tunnelmigrate.dest.instance-00000008" rw,
    "/var/lib/nova/instances/4a03fea7-e966-48e4-80ac-aa138db67243/console.log" rw,
    "/var/lib/nova/instances/4a03fea7-e966-48e4-80ac-aa138db67243/console.log" rw,
    # for qemu guest agent channel
    owner "/var/lib/libvirt/qemu/channel/target/domain-instance-00000008/**" rw,
    /dev/vhost-net rw,

  root at ubuntu-trusty-5773:/etc/apparmor.d/abstractions# dpkg -S libvirt-qemu
  libvirt-bin: /etc/apparmor.d/abstractions/libvirt-qemu

  root at ubuntu-trusty-5773:/etc/apparmor.d/abstractions# dpkg -l libvirt-bin
  Desired=Unknown/Install/Remove/Purge/Hold
  | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
  |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
  ||/ Name                                      Version                   Architecture              Description
  +++-=========================================-=========================-=========================-=======================================================================================
  ii  libvirt-bin                               1.3.1-1ubuntu10.6~cloud0  amd64                     programs for the libvirt library

  Seeing identical behavior on Xenial
  ubuntu at ubuntu-xenial-5165:~$ dpkg -l libvirt-bin
  Desired=Unknown/Install/Remove/Purge/Hold
  | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
  |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
  ||/ Name                                      Version                   Architecture              Description
  +++-=========================================-=========================-=========================-=======================================================================================
  ii  libvirt-bin                               1.3.1-1ubuntu10.8         amd64                     programs for the libvirt library

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