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AUSCERT External Security Bulletin Redistribution
ESB-2009.0006 -- [Solaris]
A Security Vulnerability in the NFS Version 4 Client Within
Solaris May Lead to a System Panic
12 January 2009
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AusCERT Security Bulletin Summary
---------------------------------
Product: NFS Version 4
Publisher: Sun Microsystems
Operating System: Solaris
OpenSolaris
Impact: Denial of Service
Access: Existing Account
CVE Names: CVE-2009-0069
Original Bulletin:
http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-66-248566-1
Revision History: January 12 2009: Added CVE Reference
January 7 2009: Initial Release
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Solution Type: Sun Alert
Solution 248566 : A Security Vulnerability in the NFS Version 4
Client Within Solaris May Lead to a System Panic
Bug ID: 6300710
Product
Solaris 10 Operating System
OpenSolaris
Date of Resolved Release: 05-Jan-2009
SA Document Body
A Security Vulnerability in the NFS Version 4 Client Within Solaris May
Lead to a System Panic
1. Impact
A security vulnerability in the NFS version 4 client within Solaris
may allow a local unprivileged user to panic the system. This is a
type of Denial of Service (DoS).
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform:
* Solaris 10 without patch 139466-02
* OpenSolaris based upon builds snv_01 through snv_101
x86 Platform:
* Solaris 10 without patch 139467-02
* OpenSolaris based upon builds snv_01 through snv_101
Notes:
1. Solaris 8 and 9 are not impacted by this issue.
2. OpenSolaris distributions may include additional bug fixes above
and beyond the build from which it was derived. The base build can be
derived as follows:
$ uname -v
snv_86
3. Systems are only impacted by this vulnerability if they are using
NFS version 4 (NFSv4) to access remote filesystems. To determine if a
system is using NFSv4, the following nfsstat(1M) command can be used:
$ nfsstat -m
/mnt from kadumane:/space/data
Flags: vers=4,proto=tcp,sec=sys,hard,intr,link,symlink,acl,rsize=1048576, wsiz
e=1048576,retrans=5,timeo=600
Attr cache: acregmin=3,acregmax=60,acdirmin=30,acdirmax=60
The "vers=4" value in the above Flags output indicates use of NFSv4.
Note that systems not using NFSv4 mount points may do so in the
future, and all systems should be secured against this threat.
3. Symptoms
Should the described issue occur, the system will panic with a stack
trace similar to the following:
vpanic(....)
mutex_vector_enter+0x31c(....)
fn_move+0x8c(3003a399e58, 3003a399e58, ...)
nfs4rename_persistent_fh+0x4f8()
nfs4rename+0x4ac()
nfs4_rename+0x58()
fop_rename+0x1c()
vn_renameat+0x20c()
rename+0xc()
syscall_trap32+0xcc()
Most of the panics due to this issue show this trace and 1st and 2nd
argument to fn_move() will be the same.
4. Workaround
To work around this issue, use NFSv3 on the NFS client by setting
NFS_CLIENT_VERSMAX to 3 in /etc/default/nfs, and remounting the
existing NFSv4 filesystems.
An example of the entry in /etc/default/nfs:
NFS_CLIENT_VERSMAX=3
To locate which NFSv4 mountpoints qualify for unmounting, the
nfsstat(1M) command can be run, as in the following example:
# nfsstat -m
/mnt from testhost:/space/data
Flags: vers=4,proto=tcp,sec=sys,hard,intr,link,symlink,acl,rsize=1048576,
wsize=1048576,retrans=5,timeo=600
Attr cache: acregmin=3,acregmax=60,acdirmin=30,acdirmax=60
The vers=4 value in the above output indicates a NFsv4 filesystem.
To unmount the NFSv4 mountpoint, the following command can be used:
# umount /mnt
Note: If the umount command shown above does not succeed, the
filesystem may be busy and a forced unmount may be necessary. A list
of processes using the filesystem can be determined with the fuser(1M)
command:
# fuser -c <mountpoint>
These processes should be terminated prior to retrying the umount
command.
Alternatively, the mountpoint can be forcibly unmounted. Note that
this may result in application errors and/or potential data
inconsistency, so this should be used with caution.
To forcibly unmount the NFSv4 mountpoint:
# umount -f <mountpoint>
To remount the filesystem:
# mount -Fnfs testhost:/space/data /mnt
To confirm that the filesystem has been properly remounted as a NFSv3
filesystem, use nfsstat(1M) and confirm that vers=3:
# nfsstat -m
/mnt from testhost:/space/data
Flags: vers=3,proto=tcp,sec=sys,hard,intr,link,symlink,
acl,rsize=32768,wsize=32768,retrans=5,timeo=600
Attr cache: acregmin=3,acregmax=60,acdirmin=30,acdirmax=60
5. Resolution
This issue is addressed in the following releases:
SPARC Platform:
* Solaris 10 with patch 139466-02 or later
* OpenSolaris based on builds snv_102 or later
x86 Platform:
* Solaris 10 with patch 139467-02 or later
* OpenSolaris based on builds snv_102 or later
For more information on Security Sun Alerts, see Technical
Instruction ID 213557.
This Sun Alert notification is being provided to you on an "AS IS"
basis. This Sun Alert notification may contain information provided by
third parties. The issues described in this Sun Alert notification may
or may not impact your system(s). Sun makes no representations,
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YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
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This Sun Alert notification contains Sun proprietary and confidential
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agreements.
Copyright 2000-2008 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved
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