Change several dangerous domains to use PrivateTmp in their unit file.
Run some services started by systemd with a private /tmp directory. This would mitigate the chance of a service making a mistake with how it handles its /tmp data allowing a user on the system to get a privilege escalation, since users would not have access to the services /tmp directory.
- Name: Daniel J Walsh
- Email: firstname.lastname@example.org
- Targeted release: [Fedora 17]
- Last updated: Tue Jan 17 2012
- Percentage of completion: 75%
It seems to be a weekly occurrence of a new CVE for some app that uses /tmp insecurely.
Privileged services should stop using /tmp and /var/tmp. These services can potentially be interfered by unprivileged users, potentially leading to process escalation. The only server applications that need to use /tmp should be for communicating with users. For example the X server, and potentially apps that use kerberos for example sssd and nfs.gssd. (Although maybe at some point we need to fix this.) Most apps that rely on using /tmp to communicate with the user can be easily broken by users having individual /tmp using pam_namespace.
systemd as of Fedora 16 has the ability to run system services with private /tmp and /var/tmp. I would like to propose that we make this the default in Fedora 17, or at least open a bugzilla on all system services that we know of that use /tmp and /var/tmp to make them use private /tmp and /var/tmp.
- Note. systemd in Fedora 16 is currently broken. This feature requires systemd-38
Benefit to Fedora
Fedora systems would be more secure, and mitigated against /tmp privilege escalation.
This bugzilla is a blocker on all services that need to change their service unit file to include PrivateTmp=True
How To Test
Administrators that expect to find services /tmp data in /tmp will have to look in a new location. Sharing data via /tmp from a user to a system service or vice versa might be broken.