Postfix pipe command and python scripts

Fabrizio Buratta extremoburo at gmail.com
Wed May 28 11:25:37 UTC 2008


Hi everybody.

This problem with selinux is exhausting my little head:

I wrote a python script in order to provide out of office mail system to my
postfix mailserver on Centos5. This script use sqlite module to connect to a
db file and store some information about email replies, users etc.  I invoke
my script from /etc/postfix/master.cf :

autoreply       unix    -       n       n       -       -       pipe
  flags= user=vacation
argv=/etc/config_files/postfix/autoresponder/vacation.py --deliver ${sender}
-- ${recipient}

whose permissions are: (ls -Z /etc/config_files/postfix/autoresponder/)

-rwxrwxrwx  vacation vacation system_u:object_r:etc_t          database.db
-rwxrwxrwx  vacation vacation system_u:object_r:postfix_pipe_exec_t
vacation.py

The latter context was set by me to allow /urs/libexec/postfix/pipe to be
able to execute my script (i wouldn't use this kind of dirty "tricks"). If i
leave with its canonical context , postfix will
complain saying it has not permission to execute vacation.py.

Assuming this configuration right,  my script is able to connect and
retrieve information by the database (select statement ) but cannot write on
it (database.db) . Take a look at audit log:

type=SYSCALL msg=audit(1211975254.056:1341): arch=c000003e syscall=2
success=no exit=-13 a0=27f4ec0 a1=42 a2=1a4 a3=1 items=0 ppid=7203 pi\
d=7212 auid=0 uid=514 gid=514 euid=514 suid=514 fsuid=514 egid=514 sgid=514
fsgid=514 tty=(none) comm="python" exe="/usr/bin/python" subj=\
root:system_r:postfix_pipe_t:s0 key=(null)
type=AVC msg=audit(1211975254.060:1342): avc:  denied  { write } for
pid=7206 comm="python" name="localUsers.db" dev=dm-0 ino=262646 scon\
text=root:system_r:postfix_pipe_t:s0 tcontext=system_u:object_r:etc_t:s0
tclass=file

I Guess python sqlite function cannot create journaling files which is
required by sqlite to modify a database (i've also tried to add a PRAGMA
statement fo change the temporary directory and python complains that it is
not writable .....even /tmp dir) . Actually if i disable selinux everyhing
works, but i don't want to do it at all.

I have no ideas anymore to solve it out. If i create a new policy package
form my audit.log using :

 audit2allow -i /var/log/audit/audit.log -m vacation > vacation.te etc....

and loading it with semodule the issue doesn't run away.

Any help will be  really appreciated

Fabrizio
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