Secure way to run other people code (sandbox) on my server?
I want to make a web service that run other people code locally... Naturally, I want to limit their code access to certain "sandbox" directory, and that they wont be able to connect to other parts of my server (DB, main webserver, etc)
Whats the best way to do it?
Run VMware/Virtualbox:
(+) I guess it's as secure as it gets.. even if someone manage to "hack".. they only hack the guest machine
(+) can limit the cpu & memory the process uses
(+) easy to setup.. just create the VM
(-) harder to "connect" the sandbox directory from the host to the guest
(-) wasting extra memory and cpu for managing the VM
Run underprivileged user:
(+) doesnt waste extra resources
(+) sandbox directory is just a plain directory
(?) cant limit cpu and memory?
(?) dont know if it's secure enough...
Any other way?
Server running Fedora Core 8, the "other" codes written in Java & C++
Answer
To limit CPU and memory, you want to set limits for groups of processes (POSIX resource limits only apply to individual processes). You can do this using cgroups.
For example, to limit memory start by mounting the memory cgroups filesystem:
# mount cgroup -t cgroup -o memory /cgroups/memory
Then, create a new sub-directory for each group, e.g.
# mkdir /cgroups/memory/my-users
Put the processes you want constrained (process with PID "1234" here) into this group:
# cd /cgroups/memory/my-users
# echo 1234 >> tasks
Set the total memory limit for the group:
# echo 1000000 > memory.limit_in_bytes
If processes in the group fork child processes, they will also be in the group.
The above group sets the resident memory limit (i.e. constrained processes will start to swap rather than using more memory). Other cgroups let you constrain other things, such as CPU time.
You could either put your server process into the group (so that the whole system with all its users fall under the limits) or get the server to put each new session into a new group.