NetBSD Problem Report #48452

From www@NetBSD.org  Mon Dec 16 17:33:35 2013
Return-Path: <www@NetBSD.org>
Received: from mail.netbsd.org (mail.netbsd.org [149.20.53.66])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(Client CN "mail.NetBSD.org", Issuer "Postmaster NetBSD.org" (not verified))
	by mollari.NetBSD.org (Postfix) with ESMTPS id 880D7A61B7
	for <gnats-bugs@gnats.NetBSD.org>; Mon, 16 Dec 2013 17:33:35 +0000 (UTC)
Message-Id: <20131216173333.AFA4CA645E@mollari.NetBSD.org>
Date: Mon, 16 Dec 2013 17:33:33 +0000 (UTC)
From: uwe@NetBSD.org
Reply-To: uwe@NetBSD.org
To: gnats-bugs@NetBSD.org
Subject: tcp_input() doesn't always verify tcp checksum
X-Send-Pr-Version: www-1.0

>Number:         48452
>Category:       kern
>Synopsis:       tcp_input() doesn't always verify tcp checksum
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 16 17:35:00 +0000 2013
>Closed-Date:    Mon Mar 05 16:21:15 +0000 2018
>Last-Modified:  Mon Mar 05 16:21:15 +0000 2018
>Originator:     Valery Ushakov
>Release:        current
>Organization:
>Environment:
NetBSD felix 6.99.25 NetBSD 6.99.25 (FELIX) #8: Wed Nov  6 16:39:05 MSK 2013  uwe@spotty:/home/uwe/work/netbsd/cvs/src/sys/arch/landisk/compile/FELIX landisk 
>Description:
A TCP SYN segment with invalid TCP checksum to a destination port that
has no listening PCB causes an RST to be generated.  The checksum is
not verified.  From a quick look it seems that it was broken in
tcp_input.c revision 1.103

date: 2000-02-12 20:19:34 +0300;  author: thorpej;  state: Exp;  lines: +92 -67\
;
In the tcp_input() path:
- Filter out multicast destinations explicitly for every incoming packet,
  not just SYNs.  Previously, non-SYN multicast destination would be
  filtered out as a side effect of PCB lookup.  Remove now redundant
  similar checks in the dropwithreset case and in syn_cache_add().
- Defer the TCP checksum until we know that we want to process the
  packet (i.e. have a non-CLOSED connection or a listen socket).

>How-To-Repeat:
Use raw socket to send manually created TCP SYN datagram with bad
checksum to a port that has no listener.  Observe that RST is sent in
reply and "discarded for bad checksum" tcp counter in netstat -s is
not incremented.

>Fix:

>Release-Note:

>Audit-Trail:

From: "Mihai Chelaru" <kefren@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/48452 CVS commit: src/sys/netinet
Date: Fri, 15 May 2015 18:03:45 +0000

 Module Name:	src
 Committed By:	kefren
 Date:		Fri May 15 18:03:45 UTC 2015

 Modified Files:
 	src/sys/netinet: tcp_input.c

 Log Message:
 Don't try to do PCB lookup for bad checksummed segments
 Fixes PR/43510 and PR/48452


 To generate a diff of this commit:
 cvs rdiff -u -r1.339 -r1.340 src/sys/netinet/tcp_input.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->closed
State-Changed-By: maxv@NetBSD.org
State-Changed-When: Mon, 05 Mar 2018 16:21:15 +0000
State-Changed-Why:
fixed


>Unformatted:

Home	PR Database Search