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[Andy Whitcroft <apw@xxxxxxxxxxxxx>]

** Changed in: linux (Ubuntu)
    Milestone: ubuntu-15.12 => ubuntu-16.01

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https://bugs.launchpad.net/bugs/1480411

Title:
  rm -r * fails to delete directories when using overlayfs in a user-
  namespace

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  rm -r * fails to delete directories when using overlayfs in a user-
  namespace.

  If overlayfs is mounted as follows,

     mount -n -t overlay overlay -o
  lowerdir=lowerdir,upperdir=upperdir,workdir=workdir mntpt

  and if lowerdir contains lowerdir/foo/bar.txt, then,

     rm -r mntpt/foo

  fails with error message,

     "rm: cannot remove ‘mntpt/foo’: Operation not permitted"

  strace shows,

      unlinkat(AT_FDCWD, "mntpt/foo", AT_REMOVEDIR) = -1 EPERM
  (Operation not permitted)

  OS details: 64-bit ubuntu 14.04.2 with the linux-generic-lts-vivid
  kernel (3.19).

  The bug does not occur on ubuntu 14.04.2 with the default linux-
  generic 3.13 kernel.

  The bug occurs for any vanilla 3.18+ kernel to which the 1-line patch,
  "overlayfs: allow unprivileged mounts" is added.  (The patch is at,
  http://kernel.ubuntu.com/git/ubuntu/ubuntu-
  vivid.git/commit/?id=78ec45495b15d27d4cc6d05cc454e30ec5b587ea)

  The bug occurs regardless of whether the filesystem underlying
  overlayfs is tmpfs or ext4.

  The bug also occurs when running ubuntu 15.04 (ubuntu vivid) in a
  virtual machine (qemu-system-x86_64).  The host is ubuntu 14.04.2 with
  the default 3.13 kernel.

  A script which reproduces the bug is attached and is also available at
  http://paste.ubuntu.com/11974137/

  Hardware: intel core2 duo processor in a macbook-4.1

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