1.1.5 Ensure nosuid option set on /tmp partition


The nosuid mount option specifies that the filesystem cannot contain setuid files.


Since the /tmp filesystem is only intended for temporary file storage, set this option to ensure that users cannot create setuid files in /tmp.


If /etc/fstab is used to mount /tmp

Edit the /etc/fstab file and add nosuid to the fourth field (mounting options) for the /tmp partition. See the fstab(5) manual page for more information.
Run the following command to remount /tmp :

# mount -o remount,nosuid /tmp


If an explicit systemd target is used to mount /tmp:

Edit /etc/systemd/system/local-fs.target.wants/tmp.mount to add nosuid to the /tmp mount options:


Run the following command to restart the systemd daemon:

# systemctl daemon-reload

Run the following command to restart tmp.mount:

# systemctl restart tmp.mount

Additional Information:

These remediation steps are based on following the remediation guidance in item 1.1.2.

If a different file name was used that name should replace tmp.mount in the path /etc/systemd/system/local-fs.target.wants/tmp.mount

The contents of /etc/systemd/system/local-fs.target.wants should exist as a symlink to the file created in /etc/systemd/system.

If the path /etc/systemd/system/local-fs.target.wants/tmp.mount does not exist this could indicate that the remediation steps from 1.1.2 were not completed successfully.

See Also