Bug 631552 – sys-cluster/slurm: root privilege escalation via "chown -R" in pkg_postinst

• Status: CONFIRMED
• Product: Gentoo Security

[Description Michael Orlitzky 2017-09-20 17:32:34 UTC]

The ebuilds for slurm call "chown -R" on the live root filesystem in pkg_postinst:

  create_folders_and_fix_permissions() {
      einfo "Fixing permissions in ${@}"
      mkdir -p ${@}
      chown -R ${PN}:${PN} ${@}
  }

  pkg_postinst() {
      paths=(
        "${EROOT}"var/${PN}/checkpoint
        ...
      )
      for folder_path in ${paths[@]}; do
        create_folders_and_fix_permissions $folder_path
      done
      ...

That can be exploited by the "slurm" user to gain root. If a hard link pointing to a root-owned file is placed in one of those $paths, then the next time slurm is reinstalled or upgraded, the "chown -R" will affect the target of the link and give ownership of the file to slurm:slurm.

For example,

  1. emerge slurm
  2. su -s /bin/sh -c 'ln /etc/passwd /var/slurm' slurm
  3. emerge slurm
  4. /etc/passwd is owned by slurm:slurm

[Comment 1 Robin Johnson 2020-04-03 23:16:21 UTC]

Unrestricting and reassigning to security@ per bug #705894

[Comment 2 Robin Johnson 2020-04-03 23:18:05 UTC]

unrestricting per bug 705894