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NetBSD Security Advisory 2008-002
=================================
Topic: Endianness issue in fast_ipsec(4)
Version: NetBSD-current: affected
NetBSD 4.0: not affected
NetBSD 3.1: affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
NetBSD 2.1: affected
NetBSD 2.0.*: affected
NetBSD 2.0: affected
Severity: IPSEC Security bypass
Fixed: NetBSD-current: October 28, 2007
NetBSD-3-1 branch: November 22, 2007
(3.1.2 will include the fix)
NetBSD-3-0 branch: November 22, 2007
(3.0.4 will include the fix)
NetBSD-3 branch: November 22, 2007
(3.2 will include the fix)
NetBSD-2-1 branch: December 01, 2007
NetBSD-2-0 branch: December 01, 2007
NetBSD-2 branch: December 01, 2007
Abstract
========
If a IPsec association is made between two hosts with
different byte orders
it is possible to bypass the IPsec policy. It is possible
for this situation
to occur if a NetBSD system is just one host, or both hosts,
involved in the
IPsec connection.
Technical Details
=================
The function ipsec4_get_ulp() assumes that ip_off is host
endian. This
means that IPsec processing, that is dependent on protocol
and/or port number,
can be bypassed.
Solutions and Workarounds
=========================
Only kernels compiled with the following option are
vulnerable to this issue:
options FAST_IPSEC
As a temporary workaround recompile the kernel with the
above option
commented out. The default NetBSD GENERIC kernels (with the
exception
of GENERIC.FAST_IPSEC) do not have this option enabled.
For all NetBSD versions, you need to obtain fixed kernel
sources,
rebuild and install the new kernel, and reboot the system.
The fixed source may be obtained from the NetBSD CVS
repository.
The following instructions briefly summarise how to upgrade
your
kernel. In these instructions, replace:
ARCH with your architecture (from uname -m), and
KERNCONF with the name of your kernel configuration
file.
To update from CVS, re-build, and re-install the kernel:
# cd src
# cvs update sys/netipsec/xform_ah.c
sys/netipsec/ipsec.c
sys/netipsec/xform_ipip.c
sys/netipsec/ipsec_output.c
sys/netipsec/ipsec_osdep.h
# ./build.sh kernel=KERNCONF
# mv /netbsd /netbsd.old
# cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd
# shutdown -r now
For more information on how to do this, see:
http:
//www.NetBSD.org/guide/en/chap-kernel.html
Thanks To
=========
Karl Knutsson for reporting this issue and supplying an
initial fix.
Arnaud Degroote for coming up with a final patch.
Revision History
================
2008-02-28 Initial release
More Information
================
Advisories may be updated as new information becomes
available.
The most recent version of this advisory (PGP signed) can be
found at
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-S
A2008-002.txt.asc
Information about NetBSD and NetBSD security can be found
at
http://www.NetBSD.org/
and http://www.NetBSD.or
g/Security/.
Copyright 2008, The NetBSD Foundation, Inc. All Rights
Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2008-002.txt,v 1.3 2008/02/28 19:27:42
adrianp Exp $
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