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		NetBSD Security Advisory 2020-001
		=================================

Topic:		Missing permissions checks for network ioctls

Version:	NetBSD-current:		affected
		NetBSD 9.0_RC1:		affected
		NetBSD 8.1:		partially affected
		NetBSD 7.x:		partially affected

Severity:	Local users can crash the machine

Fixed:		NetBSD-current:		December 16, 2019
		NetBSD-9 branch:	December 17, 2019
		NetBSD-8 branch:	December 17, 2019
		NetBSD-7 branch:	December 17, 2019

Please note that NetBSD releases prior to 7.1 are no longer supported.
It is recommended that all users upgrade to a supported release.

Abstract
========

Three network interface related ioctls that should have been only allowed
for privileged users were not adequately protected. An unprivileged user
can set network interface descriptions, get and set diagnostic data from
some atheros interfaces, and retrieve descriptor information from umb (usb
mobile network device).

Technical Details
=================

Specifically the following ioctls were missing permissions checks:

IOCTL		FUNCTION	IFACE	VERSION	HOW
- -------------------------------------------------------------------------------
SIOCGATHDIAG 	ath_ioctl	ath	*	get and set diagnostic info
SIOCSIFDESCR	ifioctl_common	*	9,CUR	set the interface description
SIOCGUMBINFO	umb_ioctl	umb	9,CUR	get descriptor info/potentially
						contains username/password
Solutions and Workarounds
=========================

Update the kernel to a fixed version and reboot.

To apply a fixed version from a releng build, fetch a fitting kern-GENERIC.tgz
from nyftp.netbsd.org and extract the fixed binaries:

cd /var/tmp
ftp https://nycdn.NetBSD.org/pub/NetBSD-daily/REL/latest/ARCH/binary/sets/kern-GENERIC.tgz
cd /
tar xzpf /var/tmp/kern-GENERIC.tgz

with the following replacements:
REL   = the release version you are using
ARCH  = your system's architecture

The following instructions describe how to upgrade your kernel by
updating your source tree and rebuilding and installing a new version.

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 -d -P src/sys/dev/ic/ath.c
	# cvs update -d -P src/sys/dev/usb/if_umb.c
	# cvs update -d -P src/sys/net/if.c
	# ./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/docs/guide/en/chap-kernel.html

The patches can be obtained from NetBSD-current with the following
commands:

cvs rdiff -u -r1.128 -r1.129 src/sys/dev/ic/ath.c
cvs rdiff -u -r1.9 -r1.10 src/sys/dev/usb/if_umb.c
cvs rdiff -u -r1.465 -r1.466 src/sys/net/if.c

Thanks To
=========

Ilja Van Sprundel for reporting this vulnerability.

More Information
================

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at

	https://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2020-001.txt.asc

Information about NetBSD and NetBSD security can be found at

	https://www.NetBSD.org/
	https://www.NetBSD.org/Security/

Copyright 2020, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2020-001.txt,v 1.1 2020/01/21 16:07:55 christos Exp $
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