dovecot - Jun 2010 - problems with shared mailboxes and other general issues

I'm also having beginner's troubles with shared mailboxes with dovecot 
1.2.11.

I've used the TestInstallation instructions for connecting to the imap 
port via openssl and issuing the setacl/getacl commands.  Those appear 
to be fine.

I'm having real difficulty with the acl_shared_dict configuration.  I'd 
prefer to just use a flat file, as I don't anticipate using shared 
folders very frequently.  I don't need a database and would greatly 
prefer not to have a dependency on our database service.  So, with this 
setting:

acl_shared_dict = file:/private/dovecot/var/etc/shared-mailboxes

The '../var/etc' directory is something like 755.  I have to create the 
file first and make it 666.  When it is updated, ownership & permissions 
are changed such that the user giving acl permissions then owns the file 
and it's 600.  I tried setting it back to 644 afterward, so other users 
could read it, but they tried setting a lock in that dir as well.

I tried this:

acl_shared_dict = 
file:/private/dovecot/var/etc/shared-list/shared-mailboxes-%u

Then I made shared-list have '1777' permissions.  Permissions-wise, this
will now work, including locks, but I'm guessing this is just plain 
wrong and I still can't verify access.

My second choice was to use sqlite for this acl_shared_dict, but, even 
though I compiled dovecot with sqlite support and 'ldd' shows that 
'../libexec/dict' is linked against sqlite libraries, when I tried this 
config:

acl_shared_dict = sqlite:/private/dovecot/etc/acl-shared-dict.conf

I get this, and dovecot fails to start up.

EUnknown dict module: sqlite


I question whether I can use sqlite for acl_shared_dict.

Furthermore, in this vein, I don't really know what the shared namespace 
should even look like.  I've been trying the imap commands LIST and 
MYRIGHTS to verify access, but there are simply no examples.  I'd rather 
expect this to work:

x myrights shared/fromuser/folder

but all I get is mailbox doesn't exist.  I know 'shared' is the 
namespace, but I just don't know how it should really be referred to.

Personally, I can live without the acl_shared_dict (from what I 
understand).  I don't need to see the shared path for subscription, I'd 
just manually add the folder path to the .subscriptions file for the 
handful of users that need it.  I just don't think it's working, though.

On a related note, I thought I'd increase debugging to see if that 
helped out any.  When I change 'mail_debug' to 'yes', as soon as
I issue
the imap login command, it logs some stuff, then kicks me out.

Jun 09 15:57:53 IMAP(tom2): Info: acl: initializing backend with data: vfile
Jun 09 15:57:53 IMAP(tom2): Info: acl: acl username = tom2
Jun 09 15:57:53 IMAP(tom2): Info: acl: owner = 1
Jun 09 15:57:53 dovecot: Error: child 6000 (imap) killed with signal 11 
(core dumps disabled)

I would assume this error is causing my problems, but for all I know, it 
could be a side-effect of verbose debugging -- to just terminate.  I see 
nothing about that in the docs, though.  imap works fine without verbose 
logging, so I'm baffled.

I have been frustrated by the shared namespace documentation.  I've been 
through it again and again, but haven't found the answers I've been 
looking for.

Here is the relevant configuration:


namespace shared {
    location = mbox:%%h/mail/shared:INDEX=%%h/mail/shared/.imap
    # everything else defaults
}

protocol imap {
   mail_plugins = quota imap_quota acl imap_acl
}

protocol lda {
   mail_plugins = acl
}

plugin {
  acl = vfile
  acl_shared_dict = 
file:/private/dovecot/var/etc/shared-list/shared-mailboxes-%u
}

On 10.6.2010, at 1.16, Tom Lieuallen wrote:
> I'm having real difficulty with the acl_shared_dict configuration. 
I'd prefer to just use a flat file, as I don't anticipate using shared
folders very frequently.  I don't need a database and would greatly prefer
not to have a dependency on our database service.  So, with this setting:
> 
> acl_shared_dict = file:/private/dovecot/var/etc/shared-mailboxes
> 
> The '../var/etc' directory is something like 755.  I have to create
the file first and make it 666.
That should work.
> When it is updated, ownership & permissions are changed such that the
user giving acl permissions then owns the file and it's 600.
That shouldn't happen. It should preserve the original file permissions. If
the file doesn't exist, it should get parent directory's permissions and
use them. Wonder if the problem is the parent dir's permissions?

It's of course also possible that there is a bug. It would speed things up a
bit if you could try this with latest v2.0 nightly snapshot if it's still
broken: http://dovecot.org/nightly/dovecot-latest.tar.gz
> I tried setting it back to 644 afterward, so other users could read it, but
they tried setting a lock in that dir as well.
Yes, lock files are created every time the file is updated (it's recreated
every time).
> I tried this:
> 
> acl_shared_dict =
file:/private/dovecot/var/etc/shared-list/shared-mailboxes-%u
That just won't work (or at least do anything useful). Each user would have
his own file, and no one else would see it.
> My second choice was to use sqlite for this acl_shared_dict, but, even
though I compiled dovecot with sqlite support and 'ldd' shows that
'../libexec/dict' is linked against sqlite libraries, when I tried this
config:
> 
> acl_shared_dict = sqlite:/private/dovecot/etc/acl-shared-dict.conf
> 
> I get this, and dovecot fails to start up.
> 
> EUnknown dict module: sqlite
Right. This is because typically all except file backend goes through dict
process, and you need to use proxy backend to do that. See for example quota
dict configuration.
> Furthermore, in this vein, I don't really know what the shared
namespace should even look like.  I've been trying the imap commands LIST
and MYRIGHTS to verify access, but there are simply no examples.  I'd rather
expect this to work:
> 
> x myrights shared/fromuser/folder
> 
> but all I get is mailbox doesn't exist.  I know 'shared' is the
namespace, but I just don't know how it should really be referred to.
That should work.. The important thing (in your setup that uses %h) is that
"fromuser"'s userdb lookup returns the expected home directory for
the user. So the username should be the same as what the user logs in with.
> Personally, I can live without the acl_shared_dict (from what I
understand).  I don't need to see the shared path for subscription, I'd
just manually add the folder path to the .subscriptions file for the handful of
users that need it.  I just don't think it's working, though.
That should work, yes.
> On a related note, I thought I'd increase debugging to see if that
helped out any.  When I change 'mail_debug' to 'yes', as soon as
I issue the imap login command, it logs some stuff, then kicks me out.
> 
> Jun 09 15:57:53 IMAP(tom2): Info: acl: initializing backend with data:
vfile
> Jun 09 15:57:53 IMAP(tom2): Info: acl: acl username = tom2
> Jun 09 15:57:53 IMAP(tom2): Info: acl: owner = 1
> Jun 09 15:57:53 dovecot: Error: child 6000 (imap) killed with signal 11
(core dumps disabled)
Signal 11 means a crash. It's always a bug. A gdb backtrace would be helpful
in fixing it. See http://dovecot.org/bugreport.html
> I have been frustrated by the shared namespace documentation.  I've
been through it again and again, but haven't found the answers I've been
looking for.
I guess it's not ideal yet, but I don't yet have any ideas how to
improve it. Maybe once you get it working, you could suggest something?
> namespace shared {
>   location = mbox:%%h/mail/shared:INDEX=%%h/mail/shared/.imap
Don't set the :INDEX directory that way. It probably won't break
anything, but it's confusing. Root level mailbox indexes share the indexes
with the originating user, but non-root level mailboxes are added under
shared/.imap/ directory rather than shared/sub/.imap/ directory.

Although .. the whole idea of using mail/shared here doesn't really seem
right. You want users to be able to share only mailboxes under shared/ and show
them as shared/user/.. without the additional shared? I don't think I've
tried that kind of a setup before. Maybe it should work .. maybe it does work
and isn't the problem. But try removing that first and see if it's
actually the cause of your problem.

Also I'm not sure if I ever tried using mbox for shared mailboxes, but I
think it should work..