Re: Linux 2.2.18pre21

Peter Samuelson
2000-11-17T07:00:21Z

[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")
chdir("../../../../../../../../../..")
chroot(".")

mkdir proc
mount -t proc none proc
cd proc/1/cwd

Two easy "get out of jail free" cards. There are other, more complex
exploits. You have added one more. They all require root privileges.

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.

Peter