Synopsis:    Low: nfs-utils security, bug fix, and enhancement update
Issue Date:  2012-02-21
CVE Numbers: CVE-2011-1749


The nfs-utils package provides a daemon for the kernel Network File System
(NFS) server, and related tools such as the mount.nfs, umount.nfs, and
showmount programs.

It was found that the mount.nfs tool did not handle certain errors
correctly when updating the mtab (mounted file systems table) file. A
local attacker could use this flaw to corrupt the mtab file.
(CVE-2011-1749)

This update also fixes the following bugs:

* The nfs service failed to start if the NFSv1, NFSv2, and NFSv4 support
was disabled (the MOUNTD_NFS_V1="no", MOUNTD_NFS_V2="no" MOUNTD_NFS_V3="no"
lines in /etc/sysconfig/nfs were uncommented) because the mountd daemon
failed to handle the settings correctly. With this update, the underlying
code has been modified and the nfs service starts successfully in the
described scenario. 

* When a user's Kerberos ticket expired, the "sh rpc.gssd" messages flooded
the /var/log/messages file. With this update, the excessive logging has
been suppressed. 

* The crash simulation (SM_SIMU_CRASH) of the rpc.statd service had a
vulnerability that could be detected by ISS (Internet Security Scanner). As
a result, the rpc.statd service terminated unexpectedly with the following
error after an ISS scan:

  rpc.statd[xxxx]: recv_rply: can't decode RPC message!
  rpc.statd[xxxx]: *** SIMULATING CRASH! ***
  rpc.statd[xxxx]: unable to register (statd, 1, udp).

However, the rpc.statd service ignored SM_SIMU_CRASH. This update removes
the simulation crash support from the service and the problem no longer
occurs. 

* The nfs-utils init scripts returned incorrect status codes in the
following cases: if the rpcgssd and rpcsvcgssd daemon were not configured,
were provided an unknown argument, their function call failed, if a program
was no longer running and a /var/lock/subsys/$SERVICE file existed, if
starting a service under an unprivileged user, if a program was no longer
running and its pid file still existed in the /var/run/ directory. With
this update, the correct codes are returned in these scenarios. 

* The "nfsstat -m" command did not display NFSv4 mounts. With this update,
the underlying code has been modified and the command returns the list of
all mounts, including any NFSv4 mounts, as expected. 

* Previously, the nfs manual pages described the fsc mount option; however,
this option is not supported. This update removes the option description
from the manual pages. 

* The nfs-utils preinstall scriptlet failed to change the default group ID
for the nfsnobody user to 65534. This update modifies the preinstall
scriptlet and the default group ID is changed to 65534 after nfs-utils
upgrade as expected. 

* The mount.nfs command with the "-o retry" option did not try to mount for
the time specified in the "retry=X" configuration option. This occurred due
to incorrect error handling by the command. With this update, the
underlying code has been fixed and the "-o retry" option works as expected.

In addition, this update adds the following enhancement:

* The noresvport option, which allows NFS clients to use insecure ports
(ports above 1023), has been added to the NFS server configuration options.

All nfs-utils users are advised to upgrade to this updated package, which
resolves these issues and adds this enhancement. After installing this
update, the nfs service will be restarted automatically.

SL5:
  i386
     nfs-utils-1.0.9-60.el5.i386.rpm
     nfs-utils-debuginfo-1.0.9-60.el5.i386.rpm
  x86_64
     nfs-utils-1.0.9-60.el5.x86_64.rpm
     nfs-utils-debuginfo-1.0.9-60.el5.x86_64.rpm

- Scientific Linux Development Team