Summary:

SELinux is preventing umount (mount_t) "unlink" to /etc/mtab (etc_t).

Detailed Description:

SELinux denied access requested by umount. /etc/mtab may be a mislabeled.
/etc/mtab default SELinux type is etc_runtime_t, but its current type is etc_t.
Changing this file back to the default type, may fix your problem.

File contexts can be assigned to a file in the following ways.

  * Files created in a directory receive the file context of the parent
    directory by default.
  * The SELinux policy might override the default label inherited from the
    parent directory by specifying a process running in context A which creates
    a file in a directory labeled B will instead create the file with label C.
    An example of this would be the dhcp client running with the dhclient_t type
    and creates a file in the directory /etc. This file would normally receive
    the etc_t type due to parental inheritance but instead the file is labeled
    with the net_conf_t type because the SELinux policy specifies this.
  * Users can change the file context on a file using tools such as chcon, or
    restorecon.

This file could have been mislabeled either by user error, or if an normally
confined application was run under the wrong domain.

However, this might also indicate a bug in SELinux because the file should not
have been labeled with this type.

If you believe this is a bug, please file a bug report
(http://bugzilla.redhat.com/bugzilla/enter_bug.cgi) against this package.

Allowing Access:

You can restore the default system context to this file by executing the
restorecon command. restorecon '/etc/mtab', if this file is a directory, you can
recursively restore using restorecon -R '/etc/mtab'.

Fix Command:

restorecon '/etc/mtab'

Additional Information:

Source Context                system_u:system_r:mount_t:s0-s0:c0.c1023
Target Context                unconfined_u:object_r:etc_t:s0
Target Objects                /etc/mtab [ file ]
Source                        umount
Source Path                   /bin/umount
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           util-linux-ng-2.14.2-11.fc11
Target RPM Packages           setup-2.8.3-1.fc11
Policy RPM                    selinux-policy-3.6.12-83.fc11
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Plugin Name                   restorecon
Host Name                     (removed)
Platform                      Linux Adventure-linux 2.6.30.8-64.fc11.i686.PAE #1
                              SMP Fri Sep 25 04:56:58 EDT 2009 i686 i686
Alert Count                   1
First Seen                    Fri 02 Oct 2009 00:18:45 EST
Last Seen                     Fri 02 Oct 2009 00:18:45 EST
Local ID                      323624b4-2c44-4c79-aa54-0fdda3b57a41
Line Numbers                  

Raw Audit Messages            

node=Adventure-linux type=AVC msg=audit(1254406725.126:27958): avc:  denied  { unlink } for  pid=7670 comm="umount" name="mtab" dev=dm-0 ino=466 scontext=system_u:system_r:mount_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:etc_t:s0 tclass=file

node=Adventure-linux type=SYSCALL msg=audit(1254406725.126:27958): arch=40000003 syscall=38 success=no exit=-13 a0=7ba4ab a1=7ba47a a2=7bcbe8 a3=4 items=0 ppid=2463 pid=7670 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="umount" exe="/bin/umount" subj=system_u:system_r:mount_t:s0-s0:c0.c1023 key=(null)



Hash String generated from  restorecon,umount,mount_t,etc_t,file,unlink
audit2allow suggests:

#============= mount_t ==============
allow mount_t etc_t:file unlink;