kernel-packages team mailing list archive

[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1555997

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

-- 
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/1555997

Title:
  overlay fs regression: chmod fails with "Operation not permitted" on
  chowned files

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  This is a regression in Xenial's kernel 4.4.0-9 or 4.4.0-10. See
  comment #3 for simple reproducer.

  ORIGINAL BUG REPORT
  ===================
  I'm investigating some failures in autopkgtest's testsuite, and stumbled over something really weird: In an ephemeral container it is apparently not possible any more to chmod files that started out being root owned and got chowned later:

  $ sudo lxc-start-ephemeral -o adt-wily
  (log in as ubuntu/ubuntu)
  ubuntu@adt-wily-hvzj1eoa:~$ echo hello | sudo tee /tmp/testfile
  [sudo] password for ubuntu:
  hello
  ubuntu@adt-wily-hvzj1eoa:~$ sudo chown ubuntu:ubuntu /tmp/testfile
  ubuntu@adt-wily-hvzj1eoa:~$ chmod +x /tmp/testfile
  chmod: changing permissions of ‘/tmp/testfile’: Operation not permitted

  However, if the file was *not* previously chowned, it works as
  expected:

  ubuntu@adt-wily-hvzj1eoa:~$ echo hello > /tmp/testfile2
  ubuntu@adt-wily-hvzj1eoa:~$ chmod +x /tmp/testfile2
  ubuntu@adt-wily-hvzj1eoa:~$ chmod -x /tmp/testfile2

  (no errors and testfile2 becomes executable)

  There is no visible permission difference in the files at all, other
  than being group-writable (but changing the group w bit in either
  direction does not change the error at all):

  -rw-r--r-- 1 ubuntu ubuntu 6 Mar 11 10:26 /tmp/testfile
  -rw-rw-r-- 1 ubuntu ubuntu 6 Mar 11 10:26 /tmp/testfile2

  ubuntu@adt-wily-hvzj1eoa:~$ stat /tmp/testfile*
    File: ‘/tmp/testfile’
    Size: 6         	Blocks: 8          IO Block: 4096   regular file
  Device: 15h/21d	Inode: 28          Links: 1
  Access: (0644/-rw-r--r--)  Uid: ( 1000/  ubuntu)   Gid: ( 1000/  ubuntu)
  Access: 2016-03-11 10:26:19.574364117 +0100
  Modify: 2016-03-11 10:26:19.574364117 +0100
  Change: 2016-03-11 10:26:21.930343210 +0100
   Birth: -
    File: ‘/tmp/testfile2’
    Size: 6         	Blocks: 8          IO Block: 4096   regular file
  Device: 15h/21d	Inode: 29          Links: 1
  Access: (0664/-rw-rw-r--)  Uid: ( 1000/  ubuntu)   Gid: ( 1000/  ubuntu)
  Access: 2016-03-11 10:26:58.730145919 +0100
  Modify: 2016-03-11 10:26:58.730145919 +0100
  Change: 2016-03-11 10:27:44.530203985 +0100
   Birth: -

  There are also no ACLs involved (I checked with getfacl).

  This does not happen with a normal lxc-start, so this might very well
  be a bug in Linux' overlayfs. However, it also does not happen with
  the more modern "sudo lxc-copy -n adt-wily --ephemeral --foreground"
  -- bug perhaps this isn't using overlayfs?

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: lxc 2.0.0~rc9-0ubuntu1
  ProcVersionSignature: Ubuntu 4.4.0-11.26-generic 4.4.4
  Uname: Linux 4.4.0-11-generic x86_64
  ApportVersion: 2.20-0ubuntu3
  Architecture: amd64
  CurrentDesktop: i3
  Date: Fri Mar 11 10:21:20 2016
  EcryptfsInUse: Yes
  PackageArchitecture: all
  SourcePackage: lxc
  UpgradeStatus: No upgrade log present (probably fresh install)
  defaults.conf:
   lxc.network.type = veth
   lxc.network.link = lxcbr0
   lxc.network.flags = up
   lxc.network.hwaddr = 00:16:3e:xx:xx:xx
  dnsmasq.conf:
   enable-tftp
   tftp-root=/tmp/tftp
   dhcp-boot=pxelinux.0
  lxc.conf: lxc.lxcpath = /srv/lxc

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1555997/+subscriptions