[Bug 1481536] Re: "cryptsetup: unknown fstype, bad password or options?" error unlocking / decrypting LUKS volume at boot

[Steve Langasek]

On Fri, Dec 04, 2015 at 03:51:50AM -0000, Richard Hansen wrote:
> I uploaded Steve's patch to my PPA:
> https://launchpad.net/~rhansen/+archive/ubuntu/bug1481536

> I haven't tested it yet.  The patch looks good to me, except I wonder
> whether the call to udev_settle() between the two blkids should be moved
> up to just after $cryptopen (see attached patch).  Thoughts?

Since there was not already a udev_settle call there, I assumed (but did not
verify) that cryptsetup operates synchronously, and only returns once the
device mapping has been set up.  We should only add one there if someone
confirms that cryptsetup *doesn't* block until the device is created.

I believe the second udev_settle call that you removed is absolutely
required /at that point/.  Even if cryptsetup synchronously ensures the
container device mapping has been set up, I don't think it ensures that the
events for the child device have been handled yet - or even added to the
event queue - so udev_settle could still return before vgchange -a has been
run.

But talking through this, I realize this also means that we still need to
call vgchange ourselves, because otherwise there's still a race condition
here even with udev_settle being called a little bit later.

I'll prepare an updated patch, and test it.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org

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https://bugs.launchpad.net/bugs/1481536

Title:
  "cryptsetup: unknown fstype, bad password or options?" error unlocking
  / decrypting LUKS volume at boot

Status in cryptsetup:
  Confirmed
Status in One Hundred Papercuts:
  Confirmed
Status in cryptsetup package in Ubuntu:
  Confirmed

Bug description:
  Since upgrading to cryptsetup-1.6.6-5ubuntu1 to replace
  cryptsetup-1.6.1-1ubuntu7 today on my Ubuntu Wily 15.10 installation,
  I have been receiving an error message at boot time after entering my
  passphrase to unlock the LUKS partition.

  I noticed that at the same time the verbiage of the prompt to enter
  the passphrase also changed, to something like "Please unlock
  <devicename>", which is a little different than before, so I'm
  guessing something in this change may have caused the error message.

  Interestingly, the error message does not impede successful system
  boot, so my suspicion is that the error is maybe not real, but just
  being incorrectly displayed.  In other words, if I successfully enter
  the passphrase, this error will appear but the system will then
  proceed to boot successfully and have the encrypted volume
  successfully mounted.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: cryptsetup 2:1.6.6-5ubuntu1
  ProcVersionSignature: Ubuntu 4.1.0-3.3-generic 4.1.3
  Uname: Linux 4.1.0-3-generic x86_64
  ApportVersion: 2.18-0ubuntu5
  Architecture: amd64
  Date: Tue Aug  4 20:46:55 2015
  InstallationDate: Installed on 2015-05-28 (68 days ago)
  InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422.1)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: cryptsetup
  UpgradeStatus: No upgrade log present (probably fresh install)
  crypttab: sda3_crypt UUID=fe4c1c1f-252e-4bcc-904c-07896f9b1361 none luks,discard

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