Against /Tmp

I'm amazed that polyinstantiation of directories via pam_namespace.so[1] is so unheard of. Setting this up fixes almost all of the qualms mentioned in the article by giving each user their own mount namespace with an isolated /tmp directory (and others if configured). Still though, this wouldn't prevent poorly written applications using /tmp from clashing with others that are running under the same user.

It's relatively easy to set up[2] and provides a pretty huge defense mitigation against abusing /tmp.

[1] https://www.man7.org/linux/man-pages/man8/pam_namespace.8.ht...

[2] https://docs.redhat.com/en/documentation/red_hat_enterprise_...

Is there an easy way to duplicate a specific process' namespace? My biggest issue with all these new features is that privatize state is how much harder it is to reproduce a state.

Back when it was just environment variables, I could pipe /proc/PID/environ to xargs and get basically the same state. Given that things like unix domain sockets may end up in $TMPDIR, I can be left unable to do certain things.

/proc/PID/root is a view of that process’s mount namespace.

Also you can use nsenter(8) to run a command (or even a shell) under another process’s mount, pid, network, etc namespace.