This will also be an issue in newton but we're waiting to end of life
newton so we won't fix this upstream there.
** Changed in: nova/ocata
Status: New => Confirmed
** Changed in: nova/pike
Status: New => Confirmed
** Changed in: nova/ocata
Importance: Undecided => High
** Changed in: nova/pike
Importance: Undecided => High
** Also affects: nova/newton
Importance: Undecided
Status: New
** Changed in: nova/newton
Status: New => Won't Fix
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https://bugs.launchpad.net/bugs/1746032
Title:
By rebuilding twice with the same "forbidden" image one can circumvent
scheduler rebuild restrictions
Status in OpenStack Compute (nova):
In Progress
Status in OpenStack Compute (nova) newton series:
Won't Fix
Status in OpenStack Compute (nova) ocata series:
Confirmed
Status in OpenStack Compute (nova) pike series:
Confirmed
Bug description:
Description
===========
Since CVE-2017-16239, we call to the scheduler when doing a rebuild
with a new image. If the scheduler refuses a rebuild because a filter
forbids the new image on the instance's host (for example,
IsolatedHostsFilter), at first there was no indication of this in the
API (bug 1744325). Currently, with the fix for bug 1744325 merged [1],
the instance goes to ERROR to indicate the refused rebuild. However,
by rebuilding again with the same "forbidden" image it is possible to
circumvent scheduler restrictions.
Steps to reproduce
==================
1. Configure IsolatedHostsFilter:
[filter_scheduler]
enabled_filters = [...],IsolatedHostsFilter
isolated_images = 41d3e5ca-14cf-436c-9413-4826b5c8bdb1
isolated_hosts = ubuntu
restrict_isolated_hosts_to_isolated_images = true
2. Have two images, one isolated and one not:
$ openstack image list
8d0581a5-ed9d-4b98-a766-a41efbc99929 | centos | active
41d3e5ca-14cf-436c-9413-4826b5c8bdb1 | cirros-0.3.5-x86_64-disk | active
cirros is the isolated one
3. Have only one hypervisor (the isolated one):
$ openstack hypervisor list
ubuntu | QEMU | 192.168.100.194 | up
5. Boot a cirros (isolated) image:
$ openstack server create \
--image 41d3e5ca-14cf-436c-9413-4826b5c8bdb1 \
--flavor m1.nano \
cirros-test-expect-success
$ openstack server list
cirros-test-expect-success | ACTIVE | [...] |
cirros-0.3.5-x86_64-disk | m1.nano
6. Rebuild the cirros instance with centos (this should be refused by
the scheduler):
$ nova --debug rebuild cirros-test-expect-success centos
DEBUG (session:722) POST call to compute for
http://192.168.100.194/compute/v2.1/servers/d9d98bf7-623e-4587-b82c-06f36abf59cb/action
used request id req-c234346a-6e05-47cf-a0cd-45f89d11e15d
8. Observe the instance going to ERROR,
but still showing the new centos image :
$ nova show cirros-test-expect-success
[...]
status | ERROR
image | centos (8d0581a5-ed9d-4b98-a766-a41efbc99929)
[...]
9. Rebuild again with the same centos image:
$ nova rebuild cirros-test-expect-success centos
10. The rebuild goes through.
Expected result
===============
At step 10, the rebuild should still be refused.
Actual result
=============
The rebuild is allowed.
Environment
===========
1. Exact version of OpenStack you are running. See the following
Was reported in Red Hat OpenStack 12, affects newton through
master.
2. Which hypervisor did you use?
libvirt+kvm
[1] https://review.openstack.org/#/c/536268/
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