[Bug 1857036] Re: `sudo --login --user USERNAME` throws `setrlimit(RLIMIT_CORE): Operation not permitted` error when run inside a container.

[Launchpad Bug Tracker]

This bug was fixed in the package sudo - 1.8.31-1ubuntu1.1

---------------
sudo (1.8.31-1ubuntu1.1) focal; urgency=medium

  * d/p/ignore-rlimit-core-failure.patch: Ignore a failure to restore the
    RLIMIT_CORE resource limit.  Linux containers don't allow RLIMIT_CORE
    to be set back to RLIM_INFINITY if we set the limit to zero, even for
    root.  RLIMIT_NPROC is also not allowed to be set back.  This is not a
    problem outside the container.
    (LP: #1857036)

 -- Bryce Harrington <bryce at canonical.com>  Wed, 15 Jul 2020 00:17:58
+0000

** Changed in: sudo (Ubuntu Focal)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1857036

Title:
  `sudo --login --user USERNAME` throws `setrlimit(RLIMIT_CORE):
  Operation not permitted` error when run inside a container.

Status in sudo package in Ubuntu:
  Fix Released
Status in sudo source package in Focal:
  Fix Released
Status in sudo source package in Groovy:
  Fix Released

Bug description:
  [Impact]
  Logging in as a sudo user in a Ubuntu Focal Linux container displays a
  warning:

    sudo: setrlimit(RLIMIT_CORE): Operation not permitted

  The warning is entirely unnecessary - the container is trying to adjust
  RLIMIT_CORE, but this isn't allowed inside a container anyway.

  While this is "just" a warning, logging into a container as sudo is a
  very common practice, so this warning risks creating confusion for LTS
  users.

  [Test Case]
  $ lxc launch ubuntu:20.04/amd64 sudo-sru-lp1857036-test
  $ lxc shell sudo-sru-lp1857036-test

  # sudo --login --user ubuntu
  sudo: setrlimit(RLIMIT_CORE): Operation not permitted
  To run a command as administrator (user "root"), use "sudo <command>".
  See "man sudo_root" for details.
  $ logout

  Enable -proposed and update
  # apt-get install sudo

  # sudo --login --user ubuntu
  $

  [Regression Potential]
  As this only affects printing of a couple warnings, the only behavioral
  change is in stderr output.

  [Discussion]
  This changes a couple warnings into equivalent debug printfs, which
  brings the sudo behavior in-line with the behavior in groovy, bionic,
  etc. and should cause no troubles.

  This patch originates from upstream, and is already in groovy's sudo
  package (which thus can be seen not to exhibit the issue).

  The upstream patch includes some new debug prints which should be
  harmless but are unnecessary to the fix so they've been removed.

  [Original Report]
  When using `sudo --login --user USERNAME` with Ubuntu Focal currently, it will correctly operate but it will also throw the following error before continuing with the logon process (which completes successfully except for the stated error):

  sudo: setrlimit(RLIMIT_CORE): Operation not permitted

  A full run of this was tested in a Focal LXD container after dropping
  to a root shell to reproduce (arstotzka is the host system, focal-test
  is the test container):

  teward at arstotzka:~$ lxc shell focal-test
  root at focal-test:~# sudo --login --user ubuntu
  sudo: setrlimit(RLIMIT_CORE): Operation not permitted
  To run a command as administrator (user "root"), use "sudo <command>".
  See "man sudo_root" for details.

  ubuntu at focal-test:~$

  This appears to be similar to this issue identified on RedHat's
  tracker: https://bugzilla.redhat.com/show_bug.cgi?id=1773148

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: sudo 1.8.29-1ubuntu1
  ProcVersionSignature: Ubuntu 4.15.0-72.81-generic 4.15.18
  Uname: Linux 4.15.0-72-generic x86_64
  ApportVersion: 2.20.11-0ubuntu14
  Architecture: amd64
  Date: Thu Dec 19 17:16:31 2019
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=C.UTF-8
   SHELL=/bin/bash
  SourcePackage: sudo
  UpgradeStatus: No upgrade log present (probably fresh install)
  VisudoCheck:
   /etc/sudoers: parsed OK
   /etc/sudoers.d/90-cloud-init-users: parsed OK
   /etc/sudoers.d/README: parsed OK

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