FreeBSD-SA-04:12.jailroute                                  Security Advisory
                                                          The FreeBSD Project

Topic:          Jailed processes can manipulate host routing tables

Category:       core
Module:         kernel
Announced:      2004-06-07
Credits:        Pawel Malachowski
Affects:        All FreeBSD 4.x releases prior to 4.10-RELEASE
Corrected:      2004-04-06 20:11:53 UTC (RELENG_4)
                2004-06-07 17:44:44 UTC (RELENG_4_9, 4.9-RELEASE-p10)
                2004-06-07 17:42:42 UTC (RELENG_4_8, 4.8-RELEASE-p23)
CVE Name:       CAN-2004-0125
FreeBSD only:   YES

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

I.   Background

The jail(2) system call allows a system administrator to lock up a
process and all its descendants inside a closed environment with very
limited ability to affect the system outside that environment, even
for processes with superuser privileges.  It is an extension of, but
far more stringent than, the traditional Unix chroot(2) system call.

The FreeBSD kernel maintains internal routing tables for the purpose
of determining which interface should be used to transmit packets.
These routing tables can be manipulated by user processes running
with superuser privileges by sending messages over a routing socket.

II.  Problem Description

A programming error resulting in a failure to verify that an attempt
to manipulate routing tables originated from a non-jailed process.

III. Impact

Jailed processes running with superuser privileges could modify host
routing tables.  This could result in a variety of consequences including
packets being sent via an incorrect network interface and packets being
discarded entirely.

IV.  Workaround

No workaround is available.

V.   Solution

Do one of the following:

1) Upgrade your vulnerable system to 4.10-RELEASE, or to the RELENG_4_8
or RELENG_4_9 security branch dated after the correction date.

OR

2) Patch your present system:

The following patch has been verified to apply to the FreeBSD 4.8 and
4.9 systems.

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

# fetch  ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:12/jailroute.patch
# fetch  ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:12/jailroute.patch.asc

b) Apply the patch.

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

c) Recompile your kernel as described in
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.

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_4
  src/sys/net/rtsock.c                                          1.44.2.13
RELENG_4_9
  src/UPDATING                                             1.73.2.89.2.11
  src/sys/conf/newvers.sh                                  1.44.2.32.2.11
  src/sys/net/rtsock.c                                      1.44.2.11.4.1
RELENG_4_8
  src/UPDATING                                             1.73.2.80.2.26
  src/sys/conf/newvers.sh                                  1.44.2.29.2.24
  src/sys/net/rtsock.c                                      1.44.2.11.2.1