144 lines
5.5 KiB
Text
144 lines
5.5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-19:24.mqueuefs Security Advisory
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The FreeBSD Project
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Topic: Reference count overflow in mqueue filesystem 32-bit compat
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Category: core
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Module: kernel
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Announced: 2019-08-20
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Credits: Karsten König, Secfault Security
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Affects: All supported versions of FreeBSD.
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Corrected: 2019-08-20 17:45:22 UTC (stable/12, 12.0-STABLE)
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2019-08-20 17:51:32 UTC (releng/12.0, 12.0-RELEASE-p10)
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2019-08-20 17:46:22 UTC (stable/11, 11.3-STABLE)
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2019-08-20 17:51:32 UTC (releng/11.3, 11.3-RELEASE-p3)
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2019-08-20 17:51:32 UTC (releng/11.2, 11.2-RELEASE-p14)
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CVE Name: CVE-2019-5603
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:https://security.FreeBSD.org/>.
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Note: This issue is related to the previously disclosed SA-19:15.mqueuefs.
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It is another instance of the same bug and as such shares the same CVE.
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I. Background
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mqueuefs(5) implements POSIX message queue file system which can be used
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by processes as a communication mechanism.
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'struct file' represents open files, directories, sockets and other
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entities.
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II. Problem Description
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System calls operating on file descriptors obtain a reference to
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relevant struct file which due to a programming error was not always put
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back, which in turn could be used to overflow the counter of affected
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struct file.
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III. Impact
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A local user can use this flaw to obtain access to files, directories,
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sockets, etc., opened by processes owned by other users. If obtained
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struct file represents a directory from outside of user's jail, it can
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be used to access files outside of the jail. If the user in question is
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a jailed root they can obtain root privileges on the host system.
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IV. Workaround
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No workaround is available. Note that the mqueuefs file system is not
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enabled by default.
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V. Solution
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Upgrade your vulnerable system to a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date,
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and reboot.
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Perform one of the following:
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1) To update your vulnerable 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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# shutdown -r +10min "Security update"
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2) To update your vulnerable 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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# fetch https://security.FreeBSD.org/patches/SA-19:24/mqueuefs.patch
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# fetch https://security.FreeBSD.org/patches/SA-19:24/mqueuefs.patch.asc
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# gpg --verify mqueuefs.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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stable/12/ r351255
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releng/12.0/ r351261
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stable/11/ r351257
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releng/11.3/ r351261
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releng/11.2/ r351261
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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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<other info on vulnerability>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5603>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:24.mqueuefs.asc>
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