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)
159 lines
6.2 KiB
Text
159 lines
6.2 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-10:06.nfsclient Security Advisory
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The FreeBSD Project
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Topic: Unvalidated input in nfsclient
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Category: core
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Module: nfsclient
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Announced: 2010-05-27
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Credits: Patroklos Argyroudis
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Affects: FreeBSD 7.2 and later.
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Corrected: 2010-05-27 03:15:04 UTC (RELENG_8, 8.1-PRERELEASE)
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2010-05-27 03:15:04 UTC (RELENG_8_0, 8.0-RELEASE-p3)
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2010-05-27 03:15:04 UTC (RELENG_7, 7.3-STABLE)
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2010-05-27 03:15:04 UTC (RELENG_7_3, 7.3-RELEASE-p1)
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2010-05-27 03:15:04 UTC (RELENG_7_2, 7.2-RELEASE-p8)
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CVE Name: CVE-2010-2020
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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:http://security.FreeBSD.org/>.
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I. Background
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The Network File System (NFS) allows a host to export some or all of its
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file systems so that other hosts can access them over the network and mount
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them as if they were on local disks. FreeBSD includes server and client
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implementations of NFS.
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II. Problem Description
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The NFS client subsystem fails to correctly validate the length of a
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parameter provided by the user when a filesystem is mounted.
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III. Impact
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A user who can mount filesystems can execute arbitrary code in the kernel.
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On systems where the non-default vfs.usermount feature has been enabled,
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unprivileged users may be able to gain superuser ("root") privileges.
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IV. Workaround
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Do not allow untrusted users to mount filesystems. To prevent unprivileged
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users from mounting filesystems, set the vfs.usermount sysctl variable to
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zero:
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# sysctl vfs.usermount=0
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Note that the default value of this variable is zero, i.e., FreeBSD is not
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affected by this vulnerability in its default configuration, and FreeBSD
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system administrators are strongly encouraged not to change this setting.
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V. Solution
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NOTE WELL: Even with this fix allowing users to mount arbitrary media
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should not be considered safe. Most of the file systems in FreeBSD were
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not built to protect safeguard against malicious devices. While such bugs
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in file systems are fixed when found, a complete audit has not been
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perfomed on the file system code.
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Perform one of the following:
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1) Upgrade your vulnerable system to 7-STABLE or 8-STABLE, or to the
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RELENG_8_0, RELENG_7_3, or RELENG_7_2 security branch dated after the
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correction date.
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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 FreeBSD 7.2, 7.3
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and 8.0 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/SA-10:06/nfsclient.patch
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# fetch http://security.FreeBSD.org/patches/SA-10:06/nfsclient.patch.asc
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b) Apply the patch.
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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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3) To update your vulnerable system via a binary patch:
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Systems running 7.2-RELEASE, 7.3-RELEASE, or 8.0-RELEASE on the i386 or
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amd64 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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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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CVS:
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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/nfsclient/nfs_vfsops.c 1.193.2.7
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src/lib/libc/sys/mount.2 1.45.2.1
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RELENG_7_3
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src/UPDATING 1.507.2.34.2.3
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src/sys/conf/newvers.sh 1.72.2.16.2.5
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src/sys/nfsclient/nfs_vfsops.c 1.193.2.5.4.2
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src/lib/libc/sys/mount.2 1.45.12.2
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RELENG_7_2
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src/UPDATING 1.507.2.23.2.11
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src/sys/conf/newvers.sh 1.72.2.11.2.12
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src/sys/nfsclient/nfs_vfsops.c 1.193.2.5.2.2
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src/lib/libc/sys/mount.2 1.45.8.2
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RELENG_8
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src/sys/nfsclient/nfs_vfsops.c 1.226.2.7
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src/lib/libc/sys/mount.2 1.45.10.2
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RELENG_8_0
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src/UPDATING 1.632.2.7.2.6
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src/sys/conf/newvers.sh 1.83.2.6.2.6
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src/sys/nfsclient/nfs_vfsops.c 1.226.2.2.2.2
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src/lib/libc/sys/mount.2 1.45.10.1.2.2
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- -------------------------------------------------------------------------
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Subversion:
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/6/ r208586
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releng/6.4/ r208586
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stable/7/ r208586
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releng/7.3/ r208586
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releng/7.2/ r208586
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releng/7.1/ r208586
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stable/8/ r208586
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releng/8.0/ r208586
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- -------------------------------------------------------------------------
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VII. References
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2020
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http://census-labs.com/news/2010/05/26/freebsd-kernel-nfsclient/
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-SA-10:06.nfsclient.asc
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