kernel-packages team mailing list archive

[Serge Hallyn <1357588@xxxxxxxxxxxxxxxxxx>]

Eric's patch makes the situation worse rather than better.

I've sent two patches to lxc which work around the issue.  Given how
touch this area is, I'm feeling skiddish and wondering whether we are
better off not touching the kernel, just teaching userspace to deal with
what's there.

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1357588

Title:
  3.13.0-24 broke nested unprivileged LXC

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  The recent security update kernel broke nested unprivileged LXC containers as those attempt to do the following:
  access("/usr/lib/x86_64-linux-gnu/lxc/dev/console", F_OK) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_BIND, NULL) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_REMOUNT|MS_BIND, NULL) = -1 EPERM (Operation not permitted)

  The user visible error looks like:
  lxc-start: Operation not permitted - failed to mount '/dev/console' on '/usr/lib/x86_64-linux-gnu/lxc/dev/console'
  lxc-start 1408142401.327 DEBUG    lxc_conf - remounting /dev/console on /usr/lib/x86_64-linux-gnu/lxc/dev/console to respect bind or remount options
  lxc-start 1408142401.327 ERROR    lxc_conf - Operation not permitted - failed to mount '/dev/console' on '/usr/lib/x86_64-linux-gnu/lxc/dev/console'

  Followed by a complete failure to start the container.
  access("/usr/lib/x86_64-linux-gnu/lxc/dev/console", F_OK) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_BIND, NULL) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_REMOUNT|MS_BIND, NULaccess("/usr/lib/x86_64-linux-gnu/lxc/dev/console", F_OK) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_BIND, NULL) = 0
  mount("/dev/console", "/usr/lib/x86_64-linux-gnu/lxc/dev/console", 0x7fff406cd9e9, MS_REMOUNT|MS_BIND, NULL) = -1 EPERM (Operation not permitted)
  L) = -1 EPERM (Operation not permitted)

  As far as I can tell, LXC isn't doing anything particularly wrong
  there and this should succeed. Serge suggested we attempt to pass
  MS_NODEV to the remount call but that didn't help either.

  There are good chances the following upstream patch fixes this:
  http://lkml.org/lkml/2014/8/13/746

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1357588/+subscriptions