ipaserver/dcerpc: use Samba-provided trust helper to establish trust
When establishing trust to Active Directory forest, RC4 is used to
encrypt trusted domain object credentials as an application-specific
material in a secure channel based on AES session key.
In FIPS mode it is not possible to use RC4 directly.
Samba 4.14 and backports to 4.13 in Fedora 33+ and RHEL 8.4+ now
provide a helper that wraps LSA RPC call CreateTrustedDomainEx2.
This helper ensures that in FIPS mode we first check that LSA session
key is AES before allowing RC4 use internally in Samba bindings. Thus,
it becomes possible to establish trust to Active Directory forest in
FIPS mode.
Adopt FreeIPA code to use the helper provided by Samba when it is
available. If neither the helper nor unprotected arcfour_encrypt utility
is available from Samba bindings, fail import of the ipaserver.dcerpc
module.
Fixes: https://pagure.io/freeipa/issue/8655
Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>