Arch Linux

YellowSnowIsBad

Member

From: /dev/null

Registered: 2010-06-11

Posts: 46

How Secure Is Chroot()?

I have some daemons that I have chrooted using jailkit. See here: http://olivier.sessink.nl/jailkit/

I was hoping to further secure these binaries using systrace: http://www.linux.com/archive/feed/51359

there are problems with the 1.6 build and I can't seem to get it compiled; I was wondering if it was even worth the effort?

So my questions for you guys are - is a chroot adequate by itself? the chrooted binaries still make system calls which is a concern for me.

Is there anything I can do to enhance the security here? perhaps apparmor/SELinux? what would you suggest?

Thanks.

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,694

Re: How Secure Is Chroot()?

Might I suggest a quick look at the shortcomings with a Google search for chroot security.  There are many issues.

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
The shortest way to ruin a country is to give power to demagogues.— Dionysius of Halicarnassus
---
How to Ask Questions the Smart Way

YellowSnowIsBad

Member

From: /dev/null

Registered: 2010-06-11

Posts: 46

Re: How Secure Is Chroot()?

Thanks for the suggestion. i have in the past read up on the insecurities of chroot; i was looking for simple alternatives.

Most of the processes i want to sandbox were things like a browser and an irc client; not exactly software that is likely to be circumvented by chroot type exploits.  There is only one binary that i was concerned with, that is mldonkey.

I am aware of some of the ways to break out of a chroot, a lot of them require root access, which i make sure chrooted binaries do not have. Others require same basic tools like interpreters or a compiler; usually only the bare essential binaries/libraries are included in my chroot environments.

Hence why i am here seeking advice; like supplementing a chrooted binary by limiting system calls with systrace. I was looking for some advice or lightweight alternatives for some basic protection. i am not running a web server or public services that could be attacked using revised methods, but more binaries that may be victim of automated exploitation such as a worm.

Thanks.

partner55083777

Member

Registered: 2010-02-02

Posts: 10

Re: How Secure Is Chroot()?

If you are running a beefy machine, you might consider running certain programs inside an (untrusted) VM.  I wouldn't suggest SELinux as it is difficult to learn, debug, and use.  I would really only consider it if you are running Fedora or something with SELinux built-in.  As you have found out, the chroot jails are not particularly secure.

If you have enough RAM, I would really suggest just running things inside their own VM.  If you have a fast enough machine, you should see very little (if any) lag.

YellowSnowIsBad

Member

From: /dev/null

Registered: 2010-06-11

Posts: 46

Re: How Secure Is Chroot()?

Thanks for the reply. Unfortunately the system i am using is a very old Socket A machine with 256mb ddr1; virtual machine is not really an option. Is AppArmor worth it's weight? Could it suppliment a chroot?

i know jails on BSD are considered pretty secure, why is there no implementation of something similar in Linux?

Last edited by YellowSnowIsBad (2011-08-11 01:03:07)

bjornh

Member

Registered: 2011-08-23

Posts: 1

Re: How Secure Is Chroot()?

I know this post is old, but:

Before you completely drop virtual machines as an option, have a look at the linux-vserver project. This solution lets you run paravirtualized guests with little to no memory hog - Only the daemons inside the pv guest take up significant memory, so if you build yourself a vm template from scratch with only the bare minimal required to run the daemon (init, essential binaries, config, devices etc) the outcome would be a PV guest running under the same kernel as your host, in a very secure isolated enviroment, eating virtually no memory at all.