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

[Bryce Harrington]

** Description changed:

- 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):
+ [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
+ 
+ Install the PPA
+ # apt-add-repository -yus ppa:bryce/sudo-sru-lp1857036-setrlimit-in-lxc
+ # apt-get install sudo
+ 
+ # sudo --login --user ubuntu
+ To run a command as administrator (user "root"), use "sudo <command>".
+ See "man sudo_root" for details.
+ $
+ 
+ [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

** Changed in: sudo (Ubuntu Focal)
     Assignee: (unassigned) => Bryce Harrington (bryce)

** Changed in: sudo (Ubuntu Focal)
   Importance: Undecided => High

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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:
  Triaged
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

  Install the PPA
  # apt-add-repository -yus ppa:bryce/sudo-sru-lp1857036-setrlimit-in-lxc
  # apt-get install sudo

  # sudo --login --user ubuntu
  To run a command as administrator (user "root"), use "sudo <command>".
  See "man sudo_root" for details.
  $

  [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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