[SSSD] [sssd PR#514][opened] Backport several UPN related patches to sssd-1-13

[jhrozek]

   URL: https://github.com/SSSD/sssd/pull/514
Author: jhrozek
 Title: #514: Backport several UPN related patches to sssd-1-13
Action: opened

PR body:
"""
There are several patches that were applied to master, but never to sssd-1-13. The patches
are needed to enable UPN logins in both direct join and trust-based setup.

The patches were already tested by one affected RHEL customer, so I'm quite certain
they work. It would be nice to run CI and Coverity to make sure we don't introduce any
regressions.

I did some basic sanity testing when backporting the fixes, but if you want to test the
patches, first create a user with an 'enterprise principal', see e.g.
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows...
then create an UPN that is different than the realm name. Restart SSSD to make sure the
subdomains are refreshed. With a trust setup, you also might need to run 'ipa
trustdomain-fetch' to make sure the suffix shows up.

Then, login using the UPN as the username.
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/514/head:pr514
git checkout pr514