Security-Enhanced Linux secures the postfix_smtp processes via flexible mandatory access control.
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd serve for the postfix_smtpd_t, postfix_smtp_t, you must turn on the authlogin_nsswitch_use_ldap boolean.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow confined applications to run with kerberos for the postfix_smtpd_t, postfix_smtp_t, you must turn on the kerberos_enabled boolean.
setsebool -P kerberos_enabled 1
You can see the context of a file using the -Z option to lsP Policy governs the access confined processes have to these files. SELinux postfix_smtp policy is very flexible allowing users to setup their postfix_smtp processes in as secure a method as possible.
The following file types are defined for postfix_smtp:
postfix_smtp_exec_t
- Set files with the postfix_smtp_exec_t type, if you want to transition an executable to the postfix_smtp_t domain.
postfix_smtp_tmp_t
- Set files with the postfix_smtp_tmp_t type, if you want to store postfix smtp temporary files in the /tmp directories.
postfix_smtpd_exec_t
- Set files with the postfix_smtpd_exec_t type, if you want to transition an executable to the postfix_smtpd_t domain.
postfix_smtpd_tmp_t
- Set files with the postfix_smtpd_tmp_t type, if you want to store postfix smtpd temporary files in the /tmp directories.
Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels.
You can see the context of a process using the -Z option to psP Policy governs the access confined processes have to files. SELinux postfix_smtp policy is very flexible allowing users to setup their postfix_smtp processes in as secure a method as possible.
The following process types are defined for postfix_smtp:
postfix_smtpd_t, postfix_smtp_t
Note: semanage permissive -a PROCESS_TYPE can be used to make a process type permissive. Permissive process types are not denied access by SELinux. AVC messages will still be generated.
The SELinux user type postfix_smtp_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note the processes UID still need to have DAC permissions.
anon_inodefs_t
postfix_prng_t
/etc/postfix/prng_exch
postfix_smtp_tmp_t
postfix_spool_maildrop_t
/var/spool/postfix/defer(/.*)?
/var/spool/postfix/deferred(/.*)?
/var/spool/postfix/maildrop(/.*)?
postfix_spool_t
/var/spool/postfix.*
postfix_var_run_t
/var/spool/postfix/pid/.*
semanage permissive can also be used to manipulate whether or not a process type is permissive.
semanage module can also be used to enable/disable/install/remove policy modules.
system-config-selinux is a GUI tool available to customize SELinux policy settings.