The use of %w in password_query leads to "Failed to expand plugin setting" error

[Aki Tuomi]

> On 14/01/2021 17:30 Filidor Wiese <fili at fili.nl> wrote:
> 
> 
> Hi,
> I'm trying to convert my existing users to a more modern password scheme by following the how-to at https://wiki.dovecot.org/HowTo/ConvertPasswordSchemes.
> One of the steps is to include the use of '%w' in the password_query, like so:
> > password_query = \
> >  SELECT domain, password, '%w' AS userdb_plain_pass, \
> >  domain as userdb_domain, concat('*:storage=', quota) AS userdb_quota_rule, 5000 as userdb_uid, 5000 as userdb_gid, '/home/%d/%n' as userdb_home \
> >  FROM users WHERE (catch='%n' AND domain='%d')
> and also to configure:
> > userdb {
> >  driver = prefetch
> >  }
> in order to combine the user/password_query into one. Now that all seemed to work well, except for one thing.
>  When a user has a % sign in their password, the following error occurs:
> > Error: Failed to expand plugin setting plain_pass = 'Tfew3322gYEp$%5Qjk0': Unknown variable '%Q'
> > 
> Which indicates that dovecot is trying to expand variables in the password.
> As a consequence, the login process fails.
> Is there some way around this behavior?
> Thanks in advance,
> Filidor Wiese
>

You might get better results with, say, base64 encoding the password. TO_BASE64() should work from 5.6 mysql. You can also try HEX encoding it.

Aki