How to run a process on Linux with very limited privileges?

Question

I would like (from code) to start a process with very limited privileges.

• It can save files, but only in its own folder and is limited by a quota.
• Can use memory within the quota.
• CPU time (including any running subprocesses) is limited by quota.
• It is impossible to talk to any other process except its own and the interface with my controller program via stdin / out.
• Unable to interact with any devices.
• Nothing is visible on the network.

(I am building a grid-esque system. Running code may be hostile.)

Here is what I have so far ... - Create some users in advance, grid00-grid99. Give each disk / memory / CPU quota as configured.

To start the process ...

• Select an unused gridxx user.
• Create a folder inside the user's home folder.
• Hard link / bin, / usr, etc. in this folder.
• Create new folders / home / gridxx and / tmp in this folder.
• Copy to program files.
• Switch to gridxx user.
• chroot to a new folder.
• Launch a new process.

Did I miss something?

Many thanks.

Answer 1

The standard limits for resource use (via ulimit ) can handle the first three, and SELinux can handle the other three. Just create a new domain for the application, assign the correct permissions and release (but not it).

Answer 2

It looks like you are looking for something like the FreeBSD jail function . (This is for FreeBSD, of course, but this page has links to similar technologies for Linux.)

Answer 3

You should be able to accomplish this with ulimit, chroot, disk quotas, and a firewall. Limiting all forms of “talk” (IPC) is difficult. In the end, you can go with a set of virtual machines.