From owner-freebsd-net Sun Dec 30 4:49:24 2001 Delivered-To: freebsd-net@freebsd.org Received: from sj-msg-core-2.cisco.com (sj-msg-core-2.cisco.com [171.69.24.11]) by hub.freebsd.org (Postfix) with ESMTP id 347C537B439 for ; Sun, 30 Dec 2001 04:49:06 -0800 (PST) Received: from mira-sjc5-2.cisco.com (mira-sjc5-2.cisco.com [171.71.163.16]) by sj-msg-core-2.cisco.com (8.11.3/8.9.1) with ESMTP id fBUCn5D17815; Sun, 30 Dec 2001 04:49:05 -0800 (PST) Received: from stewart.chicago.il.us (ssh-sj1.cisco.com [171.68.225.134]) by mira-sjc5-2.cisco.com (Mirapoint) with ESMTP id AAP91598; Sun, 30 Dec 2001 04:49:04 -0800 (PST) Message-ID: <3C2F0D40.ADFE2B6F@stewart.chicago.il.us> Date: Sun, 30 Dec 2001 06:49:05 -0600 From: Randall Stewart X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.12 i386) X-Accept-Language: en MIME-Version: 1.0 To: Mike Silbersack Cc: Bosko Milekic , net@FreeBSD.ORG Subject: Re: m_reclaim and a protocol drain References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Mike Silbersack wrote: > > On Wed, 26 Dec 2001, Randall Stewart wrote: > > > This comment facinates me. The reason we made SACK's in SCTP > > revokeable is due to the potential DOS attack that someone > > can supposedly lauch if you don't allow the stack to revoke. > > > > I can actually see the reason that Sally made the comments > > and had us change it so that SACK's are revokeable. However > > you argue to the contrary and I wonder which is correct. > > > > If you do not allow revoking it is the same as if a protocol > > does not hold a drain() fucntion. A attacker could easily > > stuff a lot of out-of-order segments at you and thus > > fill up all your mbuf's or clusters (in my current testing > > case). This would then yeild a DOS since you could no longer > > receive any segments and leave you high and dry.... > > Heh, you nailed the reverse of the problem we've seen: Right now the easy > way to cause exhaustion is to fill up _send_ buffers, via netkill. I > guess if we solve that problem, out of order segments could be used for an > attack too. > Mike: Interesting problem.. but I was thinking in terms of a outside attacker.. not someone who has a login id on your machine. That leads down another path... i.e. local machine security. R > Just FWIW, > > Mike "Silby" Silbersack > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message -- Randall R. Stewart randall@stewart.chicago.il.us 815-342-5222 (cell phone) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message