[Bug 802197] Re: no sysfs entry in /etc/mtab breaks encrypted-home

[Steve Langasek]

As we discussed, ecryptfs's current behavior - probing the mtab to
detect the location of sysfs at runtime - remains incorrect.  /sys is
the standard* location of this filesystem, there's no reason for
ecryptfs to second guess this.

*standard: /sys will be included in the upcoming revision of the FHS.

** Changed in: ecryptfs-utils (Ubuntu)
   Importance: Critical => Low

** Changed in: ecryptfs-utils (Ubuntu)
       Status: Invalid => Triaged

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Title:
  no sysfs entry in /etc/mtab breaks encrypted-home

Status in “ecryptfs-utils” package in Ubuntu:
  Triaged
Status in “util-linux” package in Ubuntu:
  Fix Released

Bug description:
  encrypted-home directories were broken with the latest upgrade of
  util-linux.

  The issue is that ecryptfs tries to find a sysfs mount point by
  reading /etc/mtab (ie, it wants to find 'sysfs' and '/sys').

  in ecryptfs/src/libecryptfs/sysfs.c , ecryptfs_get_version tries to
  get the version of ecryptfs in this kernel. and then see if it is
  capable.  That calls 'get_sysfs_mountpoint' which parses /etc/mtab for
  the sysfs entry.

  The util-linux upgrade to 2.19.1-2ubuntu1 does not write an entry in
  /etc/mtab for sysfs.

  The end resupt is that the user ends up with file *content* decrypted, but not filenames.  They'll see a bunch of filenames with "ECRYPTFS_FNEK_ENCRYPTED" in their name like:
   ECRYPTFS_FNEK_ENCRYPTED.FXbGolSeisjWM-Qojv3ajQsDcC-kITIu0KUxZdKsa5gkZBtZLX12p7AKgcrQTja6Hep3FSW8okccMX6-
  ECRYPTFS_FNEK_ENCRYPTED.FXbGolSeisjWM-Qojv3ajQsDcC-kITIu0KUxZdKsa5gkZBtZLX12p7AKggO-5p.pSThbVFaNI8aX4-6-
  ECRYPTFS_FNEK_ENCRYPTED.FXbGolSeisjWM-Qojv3ajQsDcC-kITIu0KUxZdKsa5gkZBtZLX12p7AKgirB.sNgfbm-8lk0XZWwB-A-

  1 possible fix for this is for ecryptfs to read /proc/mounts rather than /etc/mtab.
  A work around for this is to:
   a.) log in as another user, edit /etc/mtab and add 'sysfs' entry (see /proc/mounts for example), then log in as new user
   b.) backlevel util-linux and reboot (so /etc/mtab is updated with sysfs entry via old util-linux).

  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: util-linux 2.19.1-2ubuntu1
  ProcVersionSignature: Ubuntu 3.0-1.2-generic 3.0.0-rc3
  Uname: Linux 3.0-1-generic x86_64
  Architecture: amd64
  Date: Sun Jun 26 10:50:31 2011
  EcryptfsInUse: Yes
  InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta amd64 (20100318)
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: util-linux
  UpgradeStatus: Upgraded to oneiric on 2010-11-15 (222 days ago)

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