Re: Linux 2.2.18pre21

[jesse <jesse@wirex.com>]

On Fri, Nov 17, 2000 at 12:30:00AM -0600, Peter Samuelson wrote:
> Two easy "get out of jail free" cards.  There are other, more complex
> exploits.  You have added one more.  They all require root privileges.

Actually, I've heard that a chrooted _non-root_ process can find another
process with the same uid that's not chrooted and can ptrace() to pull
itself out of the jail.

I'd imagine dropping CAP_SYS_PTRACE would avoid this, though.
 
> 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.

It appears that even dropping root privileges might not be enough.

And I realize that there are a number of ways that a root process can
escape, I was mostly objecting to the assertion that chroot() was secure
because everything before the chroot call is assumed to be trusted.

-Jesse
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