Jailkeeper NPM

JailKeeper

JailKeeper was created for my needs on SpanDeX.io. SpanDeX and similar cloud services must run otherwise-unsecured shell scripts (in our case, LaTeX code which is turing-complete and can access the filesystem). Obviously this has huge security implications. Chroot jails make me a little uneasy and seem quite difficult to manage, and easy to break out of (though I'm open to decent, lightweight alternatives). SmartOS zones seem like a better choice but I don't understand them yet ;)

Thus, this is my first attempt at an alternative solution, which is to use truss or dtrace (Solaris/SmartOS or Mac OS X, respectively) to monitor all the input/output of a spawned child process. We can immediately see if a process attempts to open a file that it shouldn't, kill the process, and notify the user (and server admins) that something funny is going on.

Installation

You know the drill:

npm install jailkeeper

Usage

var spawn = require('child_process').spawn;
var childProcess = spawn('echo "hello world"', [], { cwd: './tmp/jail1' });
var jail = new JailKeeper(childProcess);

JailKeeper attaches itself to that child process and ensures that only files within the child's initial CWD are read or written to.

You can allow a jailed process more rights:

var jail = new JailKeeper(childProcess, { read: ['/usr/bin'], write: './tmp/jail2' });

This allows the jail to access binaries in /usr/bin and write to ./tmp/jail2.

JailKeeper is an EventEmitter so you can attach to this event:

jail.on('jailbreak', function (message) { // Super sad! console.log('User tried to jailbreak by attempting to "' + message.mode + '" from the file ' + message.file); }); jail.on('exit', function (code) { });

The JailKeeper itself dies upon jailbreak, or when the child process otherwise executes.