new postfix will not run.

[John Griffiths]

selinux is preventing the update of postfix to run.

The yum update of postfix includes a directory /var/lib/postfix but 
postfix is prevented from using the directory by selinux. I think the 
policy needs to be updated.


Summary:

SELinux is preventing master (postfix_master_t) "write" to ./postfix
(var_lib_t).

Detailed Description:

SELinux is preventing master (postfix_master_t) "write" to ./postfix
(var_lib_t). The SELinux type var_lib_t, is a generic type for all files 
in the
directory and very few processes (SELinux Domains) are allowed to write 
to this
SELinux type. This type of denial usual indicates a mislabeled file. By 
default
a file created in a directory has the gets the context of the parent 
directory,
but SELinux policy has rules about the creation of directories, that say 
if a
process running in one SELinux Domain (D1) creates a file in a directory 
with a
particular SELinux File Context (F1) the file gets a different File Context
(F2). The policy usually allows the SELinux Domain (D1) the ability to 
write,
unlink, and append on (F2). But if for some reason a file (./postfix) was
created with the wrong context, this domain will be denied. The usual 
solution
to this problem is to reset the file context on the target file, 
restorecon -v
'./postfix'. If the file context does not change from var_lib_t, then 
this is
probably a bug in policy. Please file a bug report
(http://bugzilla.redhat.com/bugzilla/enter_bug.cgi) against the 
selinux-policy
package. If it does change, you can try your application again to see if it
works. The file context could have been mislabeled by editing the file 
or moving
the file from a different directory, if the file keeps getting 
mislabeled, check
the init scripts to see if they are doing something to mislabel the file.

Allowing Access:

You can attempt to fix file context by executing restorecon -v './postfix'

The following command will allow this access:

restorecon './postfix'

Additional Information:

Source Context                unconfined_u:system_r:postfix_master_t
Target Context                system_u:object_r:var_lib_t
Target Objects                ./postfix [ dir ]
Source                        master
Source Path                   /usr/libexec/postfix/master
Port                          <Unknown>
Host                          elijah.suretrak21.net
Source RPM Packages           postfix-2.5.5-1.fc8
Target RPM Packages          
Policy RPM                    selinux-policy-3.0.8-117.fc8
Selinux Enabled               True
Policy Type                   targeted
MLS Enabled                   True
Enforcing Mode                Enforcing
Plugin Name                   mislabeled_file
Host Name                     elijah.suretrak21.net
Platform                      Linux elijah.suretrak21.net 
2.6.26.5-28.fc8 #1 SMP
                              Sat Sep 20 09:32:58 EDT 2008 i686 i686
Alert Count                   3
First Seen                    Thu 09 Oct 2008 09:40:21 AM EDT
Last Seen                     Fri 10 Oct 2008 02:39:57 PM EDT
Local ID                      b11cda56-461f-44af-8fd8-3866e11f4833
Line Numbers                 

Raw Audit Messages           

host=elijah.suretrak21.net type=AVC msg=audit(1223663997.824:9826): 
avc:  denied  { write } for  pid=1805 comm="master" name="postfix" 
dev=dm-0 ino=784360 scontext=unconfined_u:system_r:postfix_master_t:s0 
tcontext=system_u:object_r:var_lib_t:s0 tclass=dir

host=elijah.suretrak21.net type=SYSCALL msg=audit(1223663997.824:9826): 
arch=40000003 syscall=5 success=no exit=-13 a0=b9d8a560 a1=c2 a2=1a4 
a3=0 items=0 ppid=1758 pid=1805 auid=500 uid=0 gid=0 euid=89 suid=0 
fsuid=89 egid=89 sgid=0 fsgid=89 tty=(none) ses=1415 comm="master" 
exe="/usr/libexec/postfix/master" 
subj=unconfined_u:system_r:postfix_master_t:s0 key=(null)

Rather than write a policy change
#============= postfix_master_t ==============
allow postfix_master_t var_lib_t:dir write;

as a work around I changed the context of /var/lib/postfix to 
postfix_etc_t which allows postfix to run.

Regards,
John Griffiths