136 lines
4.7 KiB
Text
136 lines
4.7 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-EN-18:09.ip Errata Notice
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The FreeBSD Project
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Topic: IP fragment remediation causes IPv6 fragment
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reassembly failure
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Category: core
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Module: kernel
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Announced: 2018-09-27
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Credits: Kristof Provost
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Affects: FreeBSD 11.1 and FreeBSD 11.2
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Corrected: 2018-09-27 18:29:55 UTC (releng/11.2, 11.2-RELEASE-p4)
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2018-09-27 18:29:55 UTC (releng/11.1, 11.1-RELEASE-p15)
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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:https://security.FreeBSD.org/>.
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I. Background
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The recent security advisory titled SA-18:10.ip resolved an issue in the IPv4
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and IPv6 fragment reassembly code.
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II. Problem Description
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As a result of fixing the issue describe in SA-18:10.ip, a regression was
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introduced in the IPv6 fragment hashing code which could cause reassembly to
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fail.
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III. Impact
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Received IPv6 packets requiring fragment reassembly may be dropped instead of
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properly reassembled and delivered.
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IV. Workaround
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Disable IPv6 fragment reassembly, using these commands:
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% sysctl net.inet6.ip6.maxfrags=0
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On systems compiled with VIMAGE, these sysctls will need to be
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executed for each VNET.
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V. Solution
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Perform one of the following:
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1) Upgrade your system to a supported FreeBSD stable or release / security
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branch (releng) dated after the correction date.
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Afterward, reboot the system.
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2) To update your system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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Afterward, reboot the system.
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3) To update your system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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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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[FreeBSD 11.x]
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# fetch https://security.FreeBSD.org/patches/EN-18:09/ip.patch
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# fetch https://security.FreeBSD.org/patches/EN-18:09/ip.patch.asc
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# gpg --verify ip.patch.asc
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b) Apply the patch. 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:https://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 correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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releng/11.1/ r338978
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releng/11.2/ r338978
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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The security advisory that introduced the regression is available at
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<URL:https://www.freebsd.org/security/advisories/FreeBSD-SA-18:10.ip.asc>
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<URL:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=231045>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:09.ip.asc>
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