[Bug 1506139] Re: 15.10beta crashes encrypted swap partition

[Steve Langasek]

The systemd package has taken over the handling of /etc/crypttab at boot
from cryptsetup (without much coordination AFAICS), and it sounds like
its interpretation of the crypttab is buggy.

"swap" is not synonymous with "random", and should not result in the
device being clobbered, which is what is happening here.  In particular,
encrypted persistent swap needs to be supportable for users who wish to
use this for suspend to disk, and this requires a LUKS header (with
UUID).

Note however that for this use case, you *also* don't actually want to
use 'swap' as an option in /etc/crypttab, because this is defined as
"Run mkswap on the created device", and there's no need to do that if
you have a persistent crypted swap.

** Package changed: cryptsetup (Ubuntu) => systemd (Ubuntu)

** Changed in: systemd (Ubuntu)
   Importance: Undecided => High

** Changed in: systemd (Ubuntu)
     Assignee: (unassigned) => Martin Pitt (pitti)

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https://bugs.launchpad.net/bugs/1506139

Title:
  15.10beta crashes encrypted swap partition

Status in systemd package in Ubuntu:
  New

Bug description:
  Hi,

  I'm usually using a setup with three partitions on a disk

  Partition 1:  plain ext4 boot partition mounted on  /boot
  Partition 2:  luks-encrypted swap
  Partition 3: luks-encrypted btrfs for /  /home ...

  both mentioned in /etc/crypttab like

  sda2_crypt UUID=a7976d5c-6191-436d-9cf9-2cedf17d0893 none luks,swap,discard
  sda3_crypt UUID=339b9a90-8292-422d-a3cf-eeb0317e9f84 none luks,discard

  
  With several machines I have installed 15.10 beta on and in several cases I experienced the problem that the swap is not activated at boot time and that /dev/disks/by-uuid does not contain a link to the swap partition, and the previously created luks-encrypted swap is destroyed after boot: It is not a luks partition anymore and filled with random (presumably encrypted) bytes without structure. 

  I first thought that this is a problem of the setup process, and
  repaired the swap manually. But then I found the partition destroyed
  again. This happend several times on several machines.

  I am not sure yet what exactly would destroy the partition.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: cryptsetup 2:1.6.6-5ubuntu2
  ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
  Uname: Linux 4.2.0-16-generic x86_64
  ApportVersion: 2.19.1-0ubuntu2
  Architecture: amd64
  CurrentDesktop: XFCE
  Date: Wed Oct 14 18:12:58 2015
  InstallationDate: Installed on 2015-10-08 (5 days ago)
  InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150924)
  SourcePackage: cryptsetup
  UpgradeStatus: No upgrade log present (probably fresh install)
  crypttab:
   sda2_crypt UUID=a7976d5c-6191-436d-9cf9-2cedf17d0893 none luks,swap,discard
   sda3_crypt UUID=339b9a90-8292-422d-a3cf-eeb0317e9f84 none luks,discard

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