Before this change Heimdal could read KDBs. Now it can write to
them too.
Heimdal can now also dump HDBs (including KDBs) in MIT format, which
can then be imported with kdb5_util load.
This is intended to help in migrations from MIT to Heimdal by
allowing migrations from Heimdal to MIT so that it is possible
to rollback from Heimdal to MIT should there be any issues. The
idea is to allow a) running Heimdal kdc/kadmind with a KDB, or
b) running Heimdal with an HDB converted from a KDB and then
rollback by dumping the HDB and loading a KDB.
Note that not all TL data types are supported, only two: last
password change and modify-by. This is the minimum necessary.
PKINIT users may need to add support for KRB5_TL_USER_CERTIFICATE,
and for databases with K/M history we may need to add KRB5_TL_MKVNO
support.
Support for additional TL data types can be added in
lib/hdb/hdb-mitdb.c:_hdb_mdb_value2entry() and
lib/hdb/print.c:entry2mit_string_int().
The libkadm5 functions hdb_open() and close around all HDB ops. This
meant the previous implementation of kadm5_lock() and unlock would
always result in a core dump. Now we hdb_open() for write in
kadm5_lock() and hdb_close() in kadm5_unlock(), with all kadm5_s_*()
functions now not opening nor closing the HDB when the server context
keep_open flag is set.
Also, there's now kadmin(8) lock and unlock commands. These are there
primarily as a way to test the kadm5_lock()/unlock() operations, but
MIT's kadmin.local also has lock/unlock commands, and these can be
useful for scripting (though they require much care).
