dovecot - Nov 2015 - Let lmtp create target directories

Hello,

we're using vmm? to manage our postfix+dovecot virtual mail setup,
which allows us to give every virtual user a separate EUID and every
domain a separate EGID for additional security (vs. handling all
virtual mail with a single "vmail" user).

As a consequence, however, vmm must itself create the user
directories with the appropriate owners, and to do so, it requires
root rights.

I am trying to investigate getting rid of this need?. Since Dovecot
quite happily creates ~/Maildir when necessary, couldn't it also
create parents? The home directory should be trivial (same
EUID/EGID), but grandparents etc. might need a different policy
(e.g. 0/EGID for the grandparent, 0/0 for great-grandparents, etc.).

Is this something that could fall within the realm of Dovecot's
lmtp? Or is the lmtp invoked as the user and doesn't actually drop
root? If so, might there be another way?

?) http://vmm.localdomain.org/?
?) Hallo Pascal
?) http://bugs.debian.org/804382

Thanks,

-- 
@martinkrafft | http://madduck.net/ | http://two.sentenc.es/
 
"perfection is achieved, not when there is nothing more to add, but
 when there is nothing left to take away."
                                         -- antoine de saint-exup?ry
 
spamtraps: madduck.bogus at madduck.net
-------------- next part --------------
A non-text attachment was scrubbed...
Name: digital_signature_gpg.asc
Type: application/pgp-signature
Size: 1107 bytes
Desc: Digital signature (see
http://martin-krafft.net/gpg/sig-policy/999bbcc4/current)
URL:
<http://dovecot.org/pipermail/dovecot/attachments/20151126/c8243c83/attachment.sig>

On 26 Nov 2015, at 04:12, martin f krafft <madduck at madduck.net>
wrote:
> 
> Hello,
> 
> we're using vmm? to manage our postfix+dovecot virtual mail setup,
> which allows us to give every virtual user a separate EUID and every
> domain a separate EGID for additional security (vs. handling all
> virtual mail with a single "vmail" user).
> 
> As a consequence, however, vmm must itself create the user
> directories with the appropriate owners, and to do so, it requires
> root rights.
> 
> I am trying to investigate getting rid of this need?. Since Dovecot
> quite happily creates ~/Maildir when necessary, couldn't it also
> create parents? The home directory should be trivial (same
> EUID/EGID), but grandparents etc. might need a different policy
> (e.g. 0/EGID for the grandparent, 0/0 for great-grandparents, etc.).
Dovecot already creates all the parent directories. What to set to the
permissions are of course a problem.
http://wiki2.dovecot.org/SharedMailboxes/Permissions explains how it works right
now. See especially "Permissions to new /domain/user directories" and
"Permissions to new user home directories (v2.2+)".
> Is this something that could fall within the realm of Dovecot's
> lmtp? Or is the lmtp invoked as the user and doesn't actually drop
> root? If so, might there be another way?
That's the even bigger issue. The home dir creation is done with the
user's privileges, not as root. But the +t bit might help.