Add libkdc wrappers for heimbase object accessors so plugins can use audit and
request attribute APIs without consuming libheimbase. Exposed API surface is
minimal and is limited to reading array collections, and reading/creating base
and custom types.
We will use the kdc_ rather than krb5_kdc_ prefix for new public APIs exported
from libkdc. Amend the recently introduced
request_{get,set,copy,delete}_attribute APIs to conform.
Remove hdb_entry_ex and revert to the original design of hdb_entry (except with
an additional context member in hdb_entry which is managed by the free_entry
method in HDB).
In the altsecid GSS pre-authentication authorizer plugin, don't add the
REQUESTOR_SID PAC info buffer unless the client requested a TGT. It is not
relevant to application services.
Update the sample GSS pre-authentication authorizer plugin to allow the PAC to
be pinned to the authenticating user's SID.
There is still a race condition between the time the user authenticates and the
time the SID is looked up via LDAP, but it should be sufficient as an example;
if more security is required, then users should be enrolled with their SIDs.
Add a sample GSS preauth authorization plugin, which will be built and
installed if OpenLDAP is available, but otherwise not enabled (by virtue of not
being installed into the plugin directory).
The plugin authorizes federated GSS preauth clients by querying an Active
Directory domain controller for the altSecurityIdentities attribute.
Once the user entry is found, the name is canonicalized by reading the
sAMAccountName attribute and concatenating it with the KDC realm.
