Description of problem:
When using the lpadmin '-i' option to set an interface script for a printer, SELinux audit messages are seen because the script is not executable.

cupsd creates the file as /etc/cups/interfaces/$NAME, and needs to be able to modify/remove that filename.  It also needs to be able to execute it, in the same way that filters are executed.

I think what's required is:

1. a new type, cups_interface_t, which is like cups_etc_rw_t but which also allows execution.
2. files in /etc/cups/interfaces to be labelled cups_interface_t

Version-Release number of selected component (if applicable):
selinux-policy-3.3.1-91.fc9

How reproducible:
100%

Steps to Reproduce:

cat <<EOF >my-interface-script
#!/bin/sh
touch /tmp/test
EOF

lpadmin -p x -i my-interface-script
cupsenable x
accept x

echo . | lp -dx

ls -l /tmp/test
# File should exist
  
Actual results:
/tmp/test does not exist.

Expected results:
/tmp/test exists.

Additional info:
Here are the audit messages:

type=AVC msg=audit(1222701812.402:592): avc:  denied  { execute } for  pid=3556 
comm="cupsd" name="x" dev=md2 ino=1157032 scontext=system_u:system_r:cupsd_t:s0-
s0:c0.c1023 tcontext=system_u:object_r:cupsd_rw_etc_t:s0 tclass=file
type=SYSCALL msg=audit(1222701812.402:592): arch=c000003e syscall=21 success=yes
 exit=0 a0=7fff09a44f60 a1=1 a2=16 a3=0 items=0 ppid=1 pid=3556 auid=4294967295 
uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496729
5 comm="cupsd" exe="/usr/sbin/cupsd" subj=system_u:system_r:cupsd_t:s0-s0:c0.c10
23 key=(null)
type=AVC msg=audit(1222701839.391:593): avc:  denied  { execute_no_trans } for  pid=20638 comm="cupsd" path="/etc/cups/interfaces/x" dev=md2 ino=1157032 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:cupsd_rw_etc_t:s0 tclass=file
type=SYSCALL msg=audit(1222701839.391:593): arch=c000003e syscall=59 success=yes exit=0 a0=7fff09a46e30 a1=7fdc029bc420 a2=7fff09a45530 a3=7fff09a45100 items=0 ppid=3556 pid=20638 auid=4294967295 uid=4 gid=7 euid=4 suid=4 fsuid=4 egid=7 sgid=7 fsgid=7 tty=(none) ses=4294967295 comm="x" exe="/bin/bash" subj=system_u:system_r:cupsd_t:s0-s0:c0.c1023 key=(null)