From: Oren Laadan <orenl@cs.huji.ac.il>
To: linux-kernel@vger.rutgers.edu, mj@atrey.karlin.mff.cuni.cz,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: [BUG] arp replies with BOOTP [more info]
Date: Thu, 3 Dec 1998 18:20:00 +0200 (IST) [thread overview]
Message-ID: <Pine.BSI.3.96.981203180620.1405B-100000@mos220.cs.huji.ac.il> (raw)
In-Reply-To: <199812022036.WAA29482@mos220.cs.huji.ac.il>
Hi,
> It appears that while the kenerl is waiting for a reply to a BOOTP
> request sent earlier, it mishandles ARP requests. In particular,
> it replies to every "arp who-has THIS_IP" with "THIS_IP is MY_NIC_ADDR":
> that is, publish its own NIC address as matching EVERY local IP.
A quick test showed that this problem does not occur on 2.0.X kernels.
I'm not sure where exactly within 2.1.X history it appeared.
Also - a temporary, ugly and rude hack, but most importantly - that
works for me. At least until there an "official" patch. It works by
checking within arp_rcv() if the interface is even configured to some
IP, and if not - just drop the packet. So here's a hack to the file
/net/ipv4/arp.c:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*** /net/ipv4/arp.c Thu Dec 3 18:12:56 1998
--- /net/ipv4/arp.c Thu Dec 3 18:14:26 1998
***************
*** 550,555 ****
--- 550,567 ----
arp->ar_pln != 4)
goto out;
+ #if 1
+ /* XXX rude hack to prevent ARP replies during BOOTP */
+ {
+ struct in_ifaddr *ifa = in_dev->ifa_list;
+ for ( ; ifa; ifa = ifa->ifa_next)
+ if (ifa->ifa_local || ifa->ifa_address)
+ break;
+ if (!ifa)
+ goto out;
+ }
+ #endif
+
switch (dev_type) {
default:
if (arp->ar_pro != __constant_htons(ETH_P_IP))
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I am not sure, though, whether maybe I should put this piece of code
actually in icmp_rcv(), which is logically correct, however - I wasn't
sure if there were any other *bad* side effects.
I welcome all comments :-)
Oren.
__________________________________________________________________________
______ ____ ___ ___ _ __ \
MOSIX Development Group ) ) ) ) ) ( ' ) \ / Oren Laadan \
The Hebrew University / / / / / \ / / orenl@cs.huji.ac.il \
of Jerusalem, Israel ( ( (___( ___) _(_ __/ \_______________________)
http://www.mosix.cs.huji.ac.il
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prev parent reply other threads:[~1998-12-03 17:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-12-02 20:36 [BUG] arp replies with BOOTP (nfsroot) Oren Laadan
1998-12-03 16:20 ` Oren Laadan [this message]
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