Re: Linux 2.2.18pre21

H. Peter Anvin
2000-11-17T07:10:33Z

Followup to: <20001117003000.B2918@wire.cadcamlab.org>
By author: Peter Samuelson <peter@cadcamlab.org>
In newsgroup: linux.dev.kernel
>
>
> [jesse]
> > 1. Your server closes all open directory file descriptors and chroots.
> > 2. Someone manages to run some exploit code in your process space which--
>
> mkdir("foo")
> chroot("foo")

BUG: you *MUST* chdir() into the chroot jail before it does you any
good at all!

I usually recommend:

mkdir("foo");
chdir("foo");
chroot(".");

> Bottom line: once you are in the chroot jail, you must drop root
> privileges, or you defeat the purpose. Security-conscious coders know
> this; it's not Linux-specific behavior or anything.

Indeed. They also know the above.

-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."