This is a followup to bug 1513153...

Description of problem:

When postfix is configured to use dovecot-lda for local mail delivery, SELinux prevents dovecot-lda from using mmap preventing update of the mailbox index file.

# ausearch -m avc

type=AVC msg=audit(1515255440.839:61538): avc:  denied  { map } for  pid=32462 comm="dovecot-lda" path="/home/scott/Maildir/dovecot.index.log" dev="dm-3" ino=6454225 scontext=system_u:system_r:dovecot_deliver_t:s0 tcontext=system_u:object_r:mail_home_rw_t:s0 tclass=file permissive=1

Version-Release number of selected component (if applicable):

selinux-policy-targeted-3.13.1-283.19.fc27.noarch
postfix-3.2.4-1.fc27.x86_64
dovecot-2.2.32-2.fc27.x86_64

How reproducible:

Always when using dovecot-lda for mailbox delivery.

Steps to Reproduce:
1. Configure postfix normally, but specifically with the following in main.cf:
 mailbox_command = /usr/libexec/dovecot/dovecot-lda
 home_mailbox = Maildir/
2. Configure dovecot normally, but with the following setting:
 mail_location = maildir:~/Maildir
3. Deliver mail to postfix.

Actual results:

Following errors logged...

lda(scott): Error: mmap(/home/scott/Maildir/dovecot.index.log) failed: Permission denied (euid=507(scott) egid=100(users) UNIX perms appear ok (ACL/MAC wrong?))

Expected results:

Mail delivered without errors.

Additional info:

Adding the following permits normal mail delivery without errors

allow dovecot_deliver_t mail_home_rw_t:file map;