Date: Wed, 10 Oct 2001 02:35:47 -0700 From: "Crist J. Clark" <cristjc@earthlink.net> To: Tim Burgess <tburgess@whitley.unimelb.edu.au> Cc: freebsd-gnats-submit@FreeBSD.ORG, freebsd-net@FreeBSD.ORG Subject: Re: kern/31130: ipfw tee functionality causes malfunction and security hole Message-ID: <20011010023547.I387@blossom.cjclark.org> In-Reply-To: <200110090920.f999K2X17814@freefall.freebsd.org>; from cristjc@earthlink.net on Tue, Oct 09, 2001 at 02:20:02AM -0700 References: <200110090920.f999K2X17814@freefall.freebsd.org>
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On Tue, Oct 09, 2001 at 02:20:02AM -0700, Crist J. Clark wrote:
[snip]
> On the wire and the packets never get routed to the "real" 172.16.0.1.
> Trying to figure out if,
>
> a) This is the expected behavior, but is poorly documented, or
> b) Something is broken.
>
> I'm thinking (b), but still wading through src/sys/netinet to verify.
Well, I see why this happens, but still not sure if it is supposed to
happen. If we look at src/sys/netinet/ip_input.c, we see that all
diverted or teed packets are accepted by the host as destined for
itself,
#ifdef IPDIVERT
if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) {
/* Divert or tee packet */
divert_info = i;
goto ours;
}
#endif
The packets are clearly going to be processed by the gateway. You seem
to have already found this in the code snipped in your original PR,
but I didn't notice your change. Please post changes to code as
unified diffs. I now understand the 'fix' you were talking about. Have
you actually built a kernel with your modifications? Does it seem to
work?
But packets _leaving_ the system seem to be processed as one would
expect. That is, a copy is divert(4)ed and then the packet heads out
onto to the wire.
This apparent inconsistency is a bug since it is either unintended
behavior or at least undocumented behavior. But the inconsistency
gives you a temporary workaround. Instead of,
600 tee 8665 ip from any to any in
Does,
600 tee 8665 ip from any to any out
Work as you would expect?
--
Crist J. Clark cjclark@alum.mit.edu
cjclark@jhu.edu
cjc@freebsd.org
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