On Fri, 9 Oct 2009, Michal Hlavinka wrote:
I've got quite simple question from dovecot's upstream: Why do we have rw
access on mails for mail group? Why /var/mail/<username> files have 0660
<username>:mail permissions instead of 0600 permissions? The fact is, I don't
know the answer and I'd appreciate your help.
distro | group | perm
Fedora | mail | 0660
Ubuntu | mail | 0600
openSuSE | users | 0600 (user is member of users group)
debian 4.0 | mail | 0660
(Note: This is result of my own investigations on installed systems or
livecds, I don't know if any installed system had changed settings.)
Interesting thing is, that when new user is added to the system, useradd
creates /var/mail/<username> file with <username>:mail 0660 permissions, but
when you delete this file and the user gets new email, this file will be
autocreated with 0600 permissions (still <username>:group owned) and it seems
everything still works.
useradd command comes from shadow-utils and fedora contains no patch changing
permissions to 0660.
The most important question is: Is there anything that requires these files can
be read and written by mail group?
If you have any info regarding this, please share.
Just a guess, but if you run useradd from shell, your umask is likely
0002. Sendmail's umask is probably 022 as set in /etc/init.d/functions
That might explain the difference, as to why it's done that way I don't