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)
135 lines
5 KiB
Text
135 lines
5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-04:01.mksnap_ffs Security Advisory
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The FreeBSD Project
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Topic: mksnap_ffs clears file system options
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Category: core
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Module: mksnap_ffs
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Announced: 2004-01-30
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Credits: Kimura Fuyuki <fuyuki@nigredo.org>
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Wiktor Niesiobedzki <bsd@w.evip.pl>
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Affects: FreeBSD 5.1-RELEASE
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FreeBSD 5.2-RELEASE
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Corrected: 2004-01-27 19:33:16 UTC (RELENG_5_1, 5.1-RELEASE-p12)
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2004-01-29 22:54:31 UTC (RELENG_5_2, 5.2-RELEASE-p1)
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CVE Name: CAN-2004-0099
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FreeBSD only: YES
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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
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<URL:http://www.freebsd.org/security/>.
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I. Background
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Mounted filesystems can have a variety of flags set on them. Some
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flags affect performance and reliability, while others enable or
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disable particular security-related features such as the ability to
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execute a binary stored on the filesystem or the use of access control
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lists to complement normal Unix file permissions.
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The mksnap_ffs(8) command creates a `snapshot' of a filesystem. A
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`snapshot' is a static representation of the state of the filesystem
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at a particular point in time. Snapshots have a variety of uses,
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but their primary purpose is to make it possible to run fsck(8) and
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dump(8) on live filesystems.
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II. Problem Description
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The kernel interface for creating a snapshot of a filesystem is the
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same as that for changing the flags on that filesystem. Due to an
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oversight, the mksnap_ffs(8) command called that interface with only
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the snapshot flag set, causing all other flags to be reset to the
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default value.
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III. Impact
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A regularly scheduled backup of a live filesystem, or any other
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process that uses the mksnap_ffs(8) command (for instance, to provide
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a rough undelete functionality on a file server), will clear any flags
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in effect on the filesystem being snapshot. Possible consequences
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depend on local usage, but can include disabling extended access
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control lists or enabling the use of setuid executables stored on an
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untrusted filesystem.
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The mksnap_ffs(8) command is normally only available to the superuser
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and members of the `operator' group. There is therefore no risk
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of a user gaining elevated privileges directly through use of the
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mksnap_ffs(8) command unless it has been intentionally made available
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to unprivileged users.
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IV. Workaround
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Do not use the mksnap_ffs(8) command, nor the -L option of the dump(8)
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command.
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It is recommended that you delete the mksnap_ffs(8) command from your
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system to prevent accidental use:
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# rm /sbin/mksnap_ffs
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V. Solution
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Do one of the following:
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1) Upgrade your vulnerable system to the RELENG_5_1 or RELENG_5_2
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security branch dated after the correction date.
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NOTE WELL: Due to release engineering in progress at the time of this
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writing, the RELENG_5_2 security branch (5.2-RELEASE-p1)
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also includes numerous other critical bug fixes, most of
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which are not security related. Please read src/UPDATING
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for details on these changes.
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2) To patch your present system:
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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 5.1 systems]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_1.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_1.patch.asc
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[FreeBSD 5.2 systems]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_2.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:01/mksnap_ffs_5_2.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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# cd /usr/src/sbin/mksnap_ffs
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# make obj && make depend && make && make install
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You are strongly encouraged to verify that all your filesystems have
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the correct flags set. The mount(8) command can list currently mounted
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filesystems and flags. Run the following command as root:
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# mount
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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_5_1
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src/sbin/mksnap_ffs/mksnap_ffs.c 1.2.2.1
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src/sys/conf/newvers.sh 1.50.2.14
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RELENG_5_2
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src/sbin/mksnap_ffs/mksnap_ffs.c 1.5.2.1
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src/sys/conf/newvers.sh 1.56.2.3
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- -------------------------------------------------------------------------
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