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FreeBSD-SA-09:10.ipv6                                       Security Advisory
                                                          The FreeBSD Project

Topic:          Missing permission check on SIOCSIFINFO_IN6 ioctl

Category:       core
Module:         netinet6
Announced:      2009-06-10
Credits:        Hiroki Sato
Affects:        All supported versions of FreeBSD.
Corrected:      2009-06-10 10:31:11 UTC (RELENG_7, 7.2-STABLE)
                2009-06-10 10:31:11 UTC (RELENG_7_2, 7.2-RELEASE-p1)
                2009-06-10 10:31:11 UTC (RELENG_7_1, 7.1-RELEASE-p6)
                2009-06-10 10:31:11 UTC (RELENG_6, 6.4-STABLE)
                2009-06-10 10:31:11 UTC (RELENG_6_4, 6.4-RELEASE-p5)
                2009-06-10 10:31:11 UTC (RELENG_6_3, 6.3-RELEASE-p11)

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

IPv6 is a new Internet Protocol, designed to replace (and avoid many of
the problems with) the current Internet Protocol (version 4).  Many
properties of the FreeBSD IPv6 network stack can be configured via the
ioctl(2) interface.

II.  Problem Description

The SIOCSIFINFO_IN6 ioctl is missing a necessary permissions check.

III. Impact

Local users, including non-root users and users inside jails, can set
some IPv6 interface properties.  These include changing the link MTU
and disabling interfaces entirely.  Note that this affects IPv6 only;
IPv4 functionality cannot be affected by exploiting this vulnerability.

IV.  Workaround

No workaround is available, but systems without local untrusted users
are not vulnerable.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
RELENG_7_2, RELENG_7_1, RELENG_6_4, or RELENG_6_3 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 6.3, 6.4,
7.1, and 7.2 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 6.x]
# fetch http://security.FreeBSD.org/patches/SA-09:10/ipv6-6.patch
# fetch http://security.FreeBSD.org/patches/SA-09:10/ipv6-6.patch.asc

[FreeBSD 7.x]
# fetch http://security.FreeBSD.org/patches/SA-09:10/ipv6.patch
# fetch http://security.FreeBSD.org/patches/SA-09:10/ipv6.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

CVS:

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_6
  src/sys/netinet6/in6.c                                        1.51.2.13
RELENG_6_4
  src/UPDATING                                             1.416.2.40.2.9
  src/sys/conf/newvers.sh                                  1.69.2.18.2.11
  src/sys/netinet6/in6.c                                    1.51.2.12.2.2
RELENG_6_3
  src/UPDATING                                            1.416.2.37.2.16
  src/sys/conf/newvers.sh                                  1.69.2.15.2.15
  src/sys/netinet6/in6.c                                    1.51.2.11.2.1
RELENG_7
  src/sys/netinet6/in6.c                                         1.73.2.7
RELENG_7_2
  src/UPDATING                                             1.507.2.23.2.4
  src/sys/conf/newvers.sh                                   1.72.2.11.2.5
  src/sys/netinet6/in6.c                                     1.73.2.6.2.2
RELENG_7_1
  src/UPDATING                                             1.507.2.13.2.9
  src/sys/conf/newvers.sh                                   1.72.2.9.2.10
  src/sys/netinet6/in6.c                                     1.73.2.4.2.2
- -------------------------------------------------------------------------

Subversion:

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/6/                                                         r193893
releng/6.4/                                                       r193893
releng/6.3/                                                       r193893
stable/7/                                                         r193893
releng/7.2/                                                       r193893
releng/7.1/                                                       r193893
- -------------------------------------------------------------------------

VII. References

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-09:10.ipv6.asc
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