Shared mailboxes, users with dots and a bug in subscriptions

[Tobias Stein]

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