Users mapped to SELinux login sysadm_u unable to login over ssh

Issue

• Users mapped to SELinux login sysadm_u cannot login to the system over SSH.
• Other unconfined logins (e.g. the root user) can login successfully.

• An error similar to the following is seen after a failing login attempt:

   # ssh foobar@host.example.com
  foobar@host.example.com's password: 
  Unable to get valid context for foobar
  Last login: Fri Oct 04 08:10:21 2019 from ::1
  Connection to host.example.com closed.
  

• Errors similar to the following appear in logs:

  Oct  4 08:11:11 host.example.com sshd[XXXX]: error: PAM: pam_open_session(): Cannot make/remove an entry for the specified session
  Oct  4 08:11:11 host.example.com sshd[XXXX]: error: ssh_selinux_setup_pty: security_compute_relabel: Invalid argument