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)
111 lines
3.8 KiB
Text
111 lines
3.8 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-EN-08:02.tcp Errata Notice
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The FreeBSD Project
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Topic: TCP options padding
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Category: core
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Module: sys_netinet
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Announced: 2008-06-19
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Credits: Bjoern A. Zeeb, Mike Silbersack, Andre Oppermann
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Affects: 7.0-RELEASE
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Corrected: 2008-05-05 20:59:36 UTC (RELENG_7, 7.0-STABLE)
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2008-06-19 06:36:10 UTC (RELENG_7_0, 7.0-RELEASE-p2)
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For general information regarding FreeBSD Errata Notices and Security
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Advisories, including descriptions of the fields above, security
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branches, and the following sections, please visit
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<URL:http://security.freebsd.org/>.
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I. Background
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The Transmission Control Protocol (TCP) of the TCP/IP protocol suite
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provides a connection-oriented, reliable, sequence-preserving data
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stream service. TCP packets can contain "TCP options" which allow for
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enhancements to basic TCP functionality; depending on the length of
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these options, it may be necessary for padding to be added.
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II. Problem Description
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Under certain conditions, TCP options are not correctly padded.
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III. Impact
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A small number of firewalls have been reported to block incorrectly
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padded TCP SYN and SYN/ACK packets generated by FreeBSD 7.0, with the
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result that an attempt to open a TCP connection to or from an affected
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host across such a firewall will fail.
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IV. Workaround
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Disabling RFC 1323 extensions and selective acknowledgments will
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eliminate the need for TCP option padding and restore interoperability.
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Note that disabling these features may cause a reduction in performance
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on high latency networks and networks that experience frequent packet
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loss.
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To disable these features, add the following lines to /etc/sysctl.conf:
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net.inet.tcp.rfc1323=0
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net.inet.tcp.sack.enable=0
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And then run "/etc/rc.d/sysctl restart" to make the change effective.
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V. Solution
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Perform one of the following:
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1) Upgrade your affected system to 7-STABLE, or the RELENG_7_0 security
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branch dated after the correction date.
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2) To patch your present system:
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The following patch has been verified to apply to FreeBSD 7.0 systems:
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch http://security.FreeBSD.org/patches/EN-08:02/tcp.patch
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# fetch http://security.FreeBSD.org/patches/EN-08:02/tcp.patch.asc
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b) Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the revision numbers of each file that was
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corrected in FreeBSD.
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Branch Revision
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Path
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- -------------------------------------------------------------------------
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RELENG_7
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src/sys/netinet/tcp.h 1.40.2.1
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src/sys/netinet/tcp_output.c 1.141.2.6
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RELENG_7_0
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src/UPDATING 1.507.2.3.2.6
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src/sys/conf/newvers.sh 1.72.2.5.2.6
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src/sys/netinet/tcp.h 1.40.4.1
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src/sys/netinet/tcp_output.c 1.141.2.3.2.1
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- -------------------------------------------------------------------------
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VII. References
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-EN-08:02.tcp.asc
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