multiple shared/mail format namespaces

[Michal Soltys]

On January 2, 2017 at 5:58 PM Michal Soltys <soltys at ziu.info> wrote:
>> 
>> 
>> Hi,
>> 
>> Are configurations (with separate formats per namespace) - such as ...
>> 
>> namespace {
>>    type = shared
>>    list = children
>>    inbox = no
>>    separator = /
>>    subscriptions = no
>>    prefix = shared1/%%n/
>>    location = maildir:/var/mail1/%%n/
>> }
>> 
>> namespace {
>>    type = shared
>>    list = children
>>    inbox = no
>>    separator = /
>>    subscriptions = no
>>    prefix = shared2/%%n/
>>    location = mdbox:/var/mail2/%%n/
>> }
>> 
>> With separate userdbs serving part of the users with maildirs in /var/mail1/ 
>> and the other part with mdboxes in /var/mail2
>> 
>> ... valid in dovecot ?
>> 
>> To be more precise:
>> 
>> 1) Is current version dovecot expected to work with configuration as above ? 
>> E.g. if some user's mail location returned from userdb doesn't match 
>> location/format from one of the above namespaces - would it be ignored for it 
>> ? A very old version of dovecot I could check quickly (2.1.7) was segfaulting 
>> (imap processes) all the time with this kind of config. While I'll be 
>> upgrading it and the whole system to modern versions, I'm wondering if this 
>> kind of thing is formally allowed at all.
>> 
>> An interesting variation of the above setup I tested - with the second 
>> namespace "un-variabled" and pointing to single user (with matching 
>> passwd-file returning that user) managed to work somehow - but the user itself 
>> was still created on the fly for the 1st namespace - having just a directory 
>> with empty dovecot-acl-list file. This essentially seemed to have worked like 
>> a typical public profile (shared acl db didn't seem to be used either)
>> 

> On 2017-01-02 19:21, Aki Tuomi wrote:
>> Yeah, that's valid configuration. As long as they have unique prefix.
>> 
>> Aki
>> 

Well, I retested it under 2.2.27 - and the behaviour is essentially the same (segfaults).

Below is the simplified configuration under which it can be observed with 2 passwd-files
(each with 1 user, passwords removed to save space)

passwd-file local-mdbox:
nmm:{SHA256}<cut>:::nmm:/var/mail2/nmm::userdb_mail=mdbox:/var/mail2/nmm userdb_home=/var/mail2/nmm

passwd-file local-maildir:
msl:{SHA256}<cut>:::msl:/var/mail/msl::userdb_mail=maildir:/var/mail/msl userdb_home=/var/mail/msl

Both of the accounts have some mails/subfolders, nmm is sharing some of its contents to msl.

doveconf -n (note thare are some leftovers from old configuration - particularly weird last/first uids and mail_uid
using dovecot user - but those are not relevant to the issue):


# 2.2.27 (c0f36b0): /etc/dovecot/dovecot.conf
# OS: Linux 4.8.13-1-ARCH x86_64  ext4
auth_debug = yes
auth_mechanisms = plain login
disable_plaintext_auth = no
first_valid_gid = 8
first_valid_uid = 105
last_valid_gid = 8
last_valid_uid = 105
listen = *
log_path = /var/log/dovecot.log
mail_access_groups = mail
mail_debug = yes
mail_gid = mail
mail_location = maildir:/var/mail/%n
mail_plugins = acl
mail_uid = dovecot
namespace {
  inbox = yes
  location = 
  prefix = 
  separator = /
  type = private
}
namespace share1 {
  inbox = no
  list = children
  location = maildir:%%h
  prefix = shared1/%%n/
  separator = /
  subscriptions = no
  type = shared
}
namespace share2 {
  inbox = no
  list = children
  location = mdbox:%%h
  prefix = shared2/%%n/
  separator = /
  subscriptions = no
  type = shared
}
passdb {
  args = username_format=%n /etc/dovecot/local-maildir
  default_fields = userdb_uid=dovecot userdb_gid=mail
  driver = passwd-file
}
passdb {
  args = username_format=%n /etc/dovecot/local-mdbox
  default_fields = userdb_uid=dovecot userdb_gid=mail
  driver = passwd-file
}
plugin {
  acl = vfile
  acl_shared_dict = file:/var/mail/shared-database/shared-mailboxes.db
}
protocols = imap
service auth {
  unix_listener auth-userdb {
    group = mail
    mode = 0660
    user = dovecot
  }
  user = dovecot
}
service imap-login {
  inet_listener imap {
    port = 0
  }
  user = dovecot
}
service imap {
  executable = /usr/lib/dovecot/imap
}
userdb {
  driver = prefetch
}
userdb {
  args = username_format=%n /etc/dovecot/local-maildir
  default_fields = uid=dovecot gid=mail
  driver = passwd-file
}
userdb {
  args = username_format=%n /etc/dovecot/local-mdbox
  default_fields = uid=dovecot gid=mail
  driver = passwd-file
}
protocol imap {
  mail_max_userip_connections = 100
  mail_plugins = acl imap_acl
}


With the configuration and 2 passwd-files as above, all imap processes (when logged as user msl) 
constantly crash with segfaults. Replacing %%h by template such as /var/mail/%%n (as in 
my initial report) behaves the same way.

Now - IF share1 namespace is commented out or removed - everything works fine (and msl sees content shared by nmm 
under shared2/nmm/ ). Similarly - if only one shared namespace uses variables and the other points directly to some
user - no crashes then.

Any ideas ?

I can get systraces/cores (though the latter without debug symbols - but I can recompile if need be).