Rapid7 Vulnerability & Exploit Database

Oracle Linux: (CVE-2020-16120) (Multiple Advisories): Unbreakable Enterprise kernel security update

Back to Search

Oracle Linux: (CVE-2020-16120) (Multiple Advisories): Unbreakable Enterprise kernel security update

Severity
2
CVSS
(AV:L/AC:L/Au:N/C:P/I:N/A:N)
Published
10/14/2020
Created
03/11/2021
Added
03/09/2021
Modified
03/13/2021

Description

Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.

Solution(s)

  • oracle-linux-upgrade-kernel-uek
  • oracle-linux-upgrade-kernel-uek-container
  • oracle-linux-upgrade-kernel-uek-container-debug
  • oracle-linux-upgrade-kernel-uek-debug
  • oracle-linux-upgrade-kernel-uek-debug-devel
  • oracle-linux-upgrade-kernel-uek-devel
  • oracle-linux-upgrade-kernel-uek-doc
  • oracle-linux-upgrade-kernel-uek-headers
  • oracle-linux-upgrade-kernel-uek-tools
  • oracle-linux-upgrade-kernel-uek-tools-libs
  • oracle-linux-upgrade-kernel-uek-tools-libs-devel
  • oracle-linux-upgrade-perf
  • oracle-linux-upgrade-python-perf

With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.

– Scott Cheney, Manager of Information Security, Sierra View Medical Center

;