autofs (SL6)

Synopsis: Moderate: autofs security and bug fix update
Advisory ID: SLSA-2015:1344-1
Issue Date: 2015-07-22
CVE Numbers: CVE-2014-8169

It was found that program-based automounter maps that used interpreted
languages such as Python would use standard environment variables to
locate and load modules of those languages. A local attacker could
potentially use this flaw to escalate their privileges on the system.

Note: This issue has been fixed by adding the “AUTOFS_” prefix to the
affected environment variables so that they are not used to subvert the
system. A configuration option (“force_standard_program_map_env”) to
override this prefix and to use the environment variables without the
prefix has been added. In addition, warnings have been added to the manual
page and to the installed configuration file. Now, by default the standard
variables of the program map are provided only with the prefix added to
its name.

Bug fixes:

* If the “ls *” command was executed before a valid mount, the autofs
program failed on further mount attempts inside the mount point, whether
the mount point was valid or not. While attempting to mount, the “ls *”
command of the root directory of an indirect mount was executed, which led
to an attempt to mount “*”, causing it to be added to the negative map
entry cache. This bug has been fixed by checking for and not adding “*”
while updating the negative map entry cache.

* The autofs program by design did not mount host map entries that were
duplicate exports in an NFS server export list. The duplicate entries in a
multi-mount map entry were recognized as a syntax error and autofs refused
to perform mounts when the duplicate entries occurred. Now, autofs has
been changed to continue mounting the last seen instance of the duplicate
entry rather than fail, and to report the problem in the log files to
alert the system administrator.

* The autofs program did not recognize the yp map type in the master map.
This was caused by another change in the master map parser to fix a
problem with detecting the map format associated with mapping the type in
the master map. The change led to an incorrect length for the type
comparison of yp maps that resulted in a match operation failure. This bug
has been fixed by correcting the length which is used for the comparison.

* The autofs program did not update the export list of the Sun-format maps
of the network shares exported from an NFS server. This happened due to a
change of the Sun-format map parser leading to the hosts map update to
stop working on the map re-read operation. The bug has been now fixed by
selectively preventing this type of update only for the Sun-formatted
maps. The updates of the export list on the Sun-format maps are now
visible and refreshing of the export list is no longer supported for the
Sun-formatted hosts map.

* Within changes made for adding of the Sun-format maps, an incorrect
check was added that caused a segmentation fault in the Sun-format map
parser in certain circumstances. This has been now fixed by analyzing the
intent of the incorrect check and changing it in order to properly
identify the conditions without causing a fault.

* A bug in the autofs program map lookup module caused an incorrect map
format type comparison. The incorrect comparison affected the Sun-format
program maps where it led to the unused macro definitions. The bug in the
comparison has been fixed so that the macro definitions are not present
for the Sun-format program maps.


– Scientific Linux Development Team