[Bug 1892369] Re: Impossible to skip integrity test for ubuntu-server 20.04.1 iso

[Mauricio Faria de Oliveira]

focal verification done; all good.

$ lxc launch ubuntu:focal casper
$ lxc shell casper

# echo 'deb http://archive.ubuntu.com/ubuntu focal-proposed main' >/etc/apt/sources.list.d/proposed.list
# apt-cache madison casper | grep proposed
    casper |    1.445.3 | http://archive.ubuntu.com/ubuntu focal-proposed/main amd64 Packages
# apt install --yes casper
# dpkg -s casper | grep ^Version:
Version: 1.445.3
# su - ubuntu


1) Without fsck.mode=skip: check occurs (OK)

$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-5.15.0-46-generic root=/dev/mapper/nvme--vg-root ro quiet splash mitigations=off vt.handoff=7
$ sudo /usr/lib/casper/casper-md5check /tmp /dev/zero
.
Checking integrity, this may take some time (or try: fsck.mode=skip)
^C


2) With fsck.mode=skip last: check skipped (OK; FIXED!)

$ echo "$(cat /proc/cmdline) fsck.mode=skip" >/tmp/cmdline
$ sudo mount --bind /tmp/cmdline /proc/cmdline

$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-5.15.0-46-generic root=/dev/mapper/nvme--vg-root ro quiet splash mitigations=off vt.handoff=7 fsck.mode=skip

$ sudo /usr/lib/casper/casper-md5check /tmp /dev/zero
.
Check skipped.
^C
$ sudo umount /proc/cmdline


3) With fsck.mode=skip before last: check skipped (OK; no regression)

$ echo "$(cat /proc/cmdline) fsck.mode=skip workaround" >/tmp/cmdline
$ sudo mount --bind /tmp/cmdline /proc/cmdline

$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-5.15.0-46-generic root=/dev/mapper/nvme--vg-root ro quiet splash mitigations=off vt.handoff=7 fsck.mode=skip workaround

$ sudo /usr/lib/casper/casper-md5check /tmp /dev/zero
.
Check skipped.
^C



** Tags removed: verification-needed-focal
** Tags added: verification-done-focal

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https://bugs.launchpad.net/bugs/1892369

Title:
  Impossible to skip integrity test for ubuntu-server 20.04.1 iso

Status in subiquity:
  New
Status in Release Notes for Ubuntu:
  New
Status in casper package in Ubuntu:
  Fix Released
Status in casper source package in Focal:
  Fix Committed
Status in casper source package in Jammy:
  Fix Released

Bug description:
  [Impact]

   * Users cannot trivially skip the media integrity test in
     the 20.04.x installer, as ctrl-c is no longer available
     and the option 'fsck.mode=skip' is NOT honored if it is
     last in cmdline (which is usually the case for humans).

   * The impact is more severe on physical server installs,
     where usually the speed of _virtual_ optical media w/
     the BMC is really slow; impacting field/data center ops.

  [Test Plan]

   * Run casper in a container/guest with fake /proc/cmdline
     in 3 modes for 'fsck.mode=skip': (steps in comment #39).

     1) not present
     2) present, last option
     3) present, not last option

   * Test the options with 20.04.5 release candidate images.

  [Where problems could occur]

   * The patch is restricted to the option parsing in casper,
     so regressions would likely manifest as errors parsing
     kernel cmdline options or crashing casper (systemd unit).

   * The patch has been in Jammy/22.04 from the daily builds.

  [Original Description]

  It is not possible to skip the integrity test with the iso available
  at http://www.releases.ubuntu.com/20.04/ubuntu-20.04.1-live-server-
  amd64.iso .

  Bellow is a screenshot of me hitting CTRL+C to try to cancel it, without success:
  https://ibb.co/vwvtXmn

  Checking integrity can be extremely slow when mounting an image via
  virtual CD tools from Dell idrac. I didn't measure it precisely but it
  takes more than 30 minutes.

  Since the image is on a remote location and was already checked, this
  is completely useless.

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