Re: Linux 2.2.18pre21

["H. Peter Anvin" <hpa@zytor.com>]

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."
http://www.zytor.com/~hpa/puzzle.txt
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/