gpjt / pam-unshare

pam-unshare

A PAM module that switches into a PID namespace, with /proc correctly mounted.

Just a sketch at the moment -- it seems to work fine, but logs too much and probably contains errors.

Suggestions/pull requests welcome!

How to use it

Compile, and copy pam_unshare.so to /lib/security/.

In one of the pam config files -- say, /etc/pam.d/su, add a line saying this:

session required      pam_unshare.so

This will mean that anyone who uses su will wind up in a separate process namespace. ps and everything in /proc will reflect that -- the rest of the processes on the system will be invisible. You can affect other tools (say, sshd) by changing their respective pam.d config files.

NB. this is not something you'd want to leave in there for root; a TODO is definitely make this module a do-nothing for root, and perhaps to allow you to specify a list of users who are likewise unaffected...

How it works

See this blog post.

Acknowledgements

Inspiration drawn from Jameson Little's simple-pam and from Ed Schmollinger's pam-chroot.

License

MIT-licensed, see LICENSE.txt.

pam-unshare's Issues

Support cgroup PID namespaces

Linux 4.6 allows for /proc/$PID/cgroup to be namespaced out with a new CLONE_NEWCGROUP flag for clone(2)/unshare(2). Without this the different unshares will still see the full host cgroup hierarchy, but with this flag each unshare will get a new cgroup namespace for itself.