3571e53040
patches for easier mirroring, to eliminate a special copy, to make www.freebsd.org/security a full copy of security.freebsd.org and be eventually be the same. For now files are just sitting there. The symlinks are missing. Discussed on: www (repository location) Discussed with: simon (so)
155 lines
5.2 KiB
Text
155 lines
5.2 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
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FreeBSD-SA-01:53 Security Advisory
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FreeBSD, Inc.
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Topic: ipfw `me' on P2P interfaces matches remote address
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Category: core
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Module: ipfw
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Announced: 2001-08-17
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Credits: Igor M Podlesny <poige@morning.ru>
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Affects: FreeBSD 4-STABLE after February 20, 2001 and prior
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to the correction date
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FreeBSD 4.3-RELEASE
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Corrected: 2001-07-17 10:50:01 UTC (FreeBSD 4.3-STABLE)
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2001-07-18 06:56:23 UTC (RELENG_4_3)
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FreeBSD only: YES
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I. Background
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ipfw is a system facility which allows IP packet filtering,
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redirecting, and traffic accounting. ipfw `me' rules are filter rules
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that specify a source or destination address of `me', intended to
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match any IP address configured on a local interface.
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II. Problem Description
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A flaw in the implementation of the ipfw `me' rules when used in
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conjunction with point-to-point interfaces results in filter rules
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which match the remote IP address of the point-to-point interface in
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addition to the intended local IP address.
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III. Impact
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IP datagrams with a source or destination IP address of a remote
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point-to-point link may be handled in a way unintended by the system
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administrator.
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For example, given an interface such as
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tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
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inet 1.1.1.1 --> 2.2.2.2 netmask 0xff000000
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and this ipfw rule:
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00010 allow ip from me to any
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packets with a source address of 2.2.2.2 would be allowed to pass when
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the administrator may have reasonably expected it not to match this
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rule.
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IV. Workaround
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Do not use ipfw `me' rules. Rewrite any existing `me' rules to use
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explicit IP addresses.
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V. Solution
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One of the following:
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1) Upgrade your vulnerable FreeBSD system to 4.3-STABLE or the
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RELENG_4_3 security branch after the respective correction dates.
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2) FreeBSD 4.x systems prior to the correction date:
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The following patches have been verified to apply to FreeBSD
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4.3-RELEASE and 4-STABLE dated prior to the correction date.
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Download the patch and the detached PGP signature from the following
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locations, and verify the signature using your PGP utility.
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# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:53/ipfw.patch
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# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:53/ipfw.patch.asc
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# cd /usr/src
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# patch -p < /path/to/patch
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# install -c -m 0444 -o root -g wheel /usr/src/sys/netinet/in_var.h /usr/include/netinet/
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# cd /usr/src/sbin/ipfw
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# make depend && make all install
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The following steps will be different depending upon whether your
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system has ipfw compiled into the kernel or is using the ipfw KLD. If
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the output of `kldstat' includes `ipfw.ko', then you are using the KLD
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and should follow the directions listed in (2a) below. Otherwise, if
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your kernel configuration file contains the line `options IPFIREWALL',
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you should follow the directions listed in (2b) below.
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2a) Execute the following commands as root:
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# cd /usr/src/sys/modules/ipfw
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# make depend && make all install
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2b) Rebuild and reinstall your kernel as described in
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http://www.freebsd.org/handbook/kernelconfig.html
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In either case 2a) or 2b), you must reboot your system to load the new
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module or kernel.
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3) FreeBSD 4.3-RELEASE systems:
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An experimental upgrade package is available for users who wish to
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provide testing and feedback on the binary upgrade process. This
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package may be installed on FreeBSD 4.3-RELEASE systems only, and is
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intended for use on systems for which source patching is not practical
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or convenient.
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If you use the upgrade package, feedback (positive or negative) to
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security-officer@FreeBSD.org is requested so we can improve the
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process for future advisories.
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During the installation procedure, backup copies are made of the
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files which are replaced by the package. These backup copies will
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be reinstalled if the package is removed, reverting the system to a
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pre-patched state.
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:53/security-patch-ipfw-01.53.tgz
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:53/security-patch-ipfw-01.53.tgz.asc
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Verify the detached PGP signature using your PGP utility.
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# pkg_add security-patch-ipfw-01:53.tgz
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Restart your system after applying the patch.
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VI. Correction details
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The following list contains the $FreeBSD$ revision numbers of each
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file that was corrected, for the supported branches of FreeBSD. The
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$FreeBSD$ revision of installed sources can be examined using the
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ident(1) command.
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[FreeBSD 4.3-STABLE]
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Revision Path
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1.33.4.1 src/sys/netinet/in_var.h
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[RELENG_4_3]
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Revision Path
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1.33.2.2 src/sys/netinet/in_var.h
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VII. References
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<URL:http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/in_var.h#rev1.39>
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-----BEGIN PGP SIGNATURE-----
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-----END PGP SIGNATURE-----
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