Shared mailboxes, users with dots and a bug in subscriptions

[Aki Tuomi]

> On 28/01/2021 15:15 Tobias Stein <tobias_stein at rockstable.it> wrote:
> 
>  
> Hi,
> 
> i'm running Dovecot 2.3.14.alpha0 with shared namespaces
> and stumbled across some errors messages logged,
> when the list of subscribed mailboxes is queried by a client.
> For every distinct account of in the list of subscriptions
> two corresponding lines are logged:
> 
> Jan 28 11:42:34 mx1 dovecot: auth: missing passwd file: /etc/dovecot/private/example/users
> Jan 28 11:42:34 mx1 dovecot: auth: missing passwd file: /etc/dovecot/private/example/users
> Jan 28 11:42:34 mx1 dovecot: auth: missing passwd file: /etc/dovecot/private/example/users
> Jan 28 11:42:36 mx1 dovecot: imap(example_user at example.com)<3638><xl6li/O5VsVfWxyn>: Error: mkdir(/var/run/dovecot/user-not-found/noc at example) failed: Permission denied (euid=109(vmail) egid=118(vmail) missing +w perm: /var/run/dovecot, dir owned by 0:0 mode=0755)
> Jan 28 11:42:36 mx1 dovecot: imap(example_user at example.com)<3638><xl6li/O5VsVfWxyn>: Error: mkdir(/var/run/dovecot/user-not-found/info at example) failed: Permission denied (euid=109(vmail) egid=118(vmail) missing +w perm: /var/run/dovecot, dir owned by 0:0 mode=0755)
> Jan 28 11:42:36 mx1 dovecot: imap(example_user at example.com)<3638><xl6li/O5VsVfWxyn>: Error: mkdir(/var/run/dovecot/user-not-found/root at example) failed: Permission denied (euid=109(vmail) egid=118(vmail) missing +w perm: /var/run/dovecot, dir owned by 0:0 mode=0755)
> 
> Similar messages are logged,
> when invalid entries are listed in '/var/lib/dovecot/db/shared-mailboxes',
> which i already pruned and haven't received them anymore since.
> 
> I think these errors are caused by an unintended behaviour
> when writing "~/Maildir/subscriptions",
> which looks (shortened) like this.
> 
> V	2
> 
> INBOX/INBOX
> shared/noc at example	com/INBOX
> shared/info at example	com/INBOX
> shared/root at example	com/test
> shared/root at example	com/test	test_sub
> 
> The subscription-file.c
> explodes the name on every hierarchy separator ('.','\0') and
> inserts a TAB character. Unfortunately it also explodes on
> the DNS label delimiter „.‟. This should probably be fixed
> by passing a structure containing the required information
> to the formatter to distinguish mailboxes from domain-names.
> 
> Subscription in combination with multiple domains and
> shared mailboxes seems broken to me. Actually i can't even explain to me,
> why it is working in face of the errors. :-)
> 
> 
> Unfortunately in Maildir++ the separator dot is hard-coded.
> 
> There is a very old thread on this mailing list,
> that suggests using „auth_username_translation‟
> to replace dots with a different character,
> but this idea is getting worse the longer i think about it.
> 
> I absolutely dislike the idea to set LAYOUT=fs,
> namespace/separator = § to change the separators
> to split on, because this would mean to restructure the
> physical layout of all mailboxes (hierarchically) and
> mess around with lots of files.
> 
> 
> I attached a dovecot-sysreport to reproduce the behaviour.
> 
> /etc/dovecot/private/example.com/users looks like this:
> ###    user:password:uid:gid:(gecos):home:(shell):extra_fields
> noc:{SSHA512}_hash_::::::
> info:{SSHA512}_hash_::::::
> root:{SSHA512}_hash_::::::
> 
> Please correct me if i'm wrong or
> point me to a workaround,
> but i think the layout code needs some love. :-)
> 
> 
> Best regards
> Tobias


You should probably add :LAYOUT=FS on your mail locations. This will change the folder naming into foo/bar/baz instead of .foo.bar.baz.

Aki