[Samba] Strange problem with winbind on linux domain member (works for 2 minutes...)

[Jakob Curdes]

Hello all, I solved the problem with winbind not working after an 
upgrade of an Ubuntu 20 SMB server to U24; it was an apparmor issue.
Strangely, the standard samba apparmor profiles prevented these two 
programs from being executed:

/usr/libexec/samba/samba-dcerpcd
/usr/libexec/samba/rpcd_lsad

I found the relevant DENIED entries in kernel.log.
After setting these to complain mode, winbind worked, and I now upgraded 
the apparmor profiles using aa-logprof and set everything back to 
enforcing mode.
Now everything works as expected.

I also sanitized my smb.conf after the hints of Rowland.

Thanks everybody and especially the SAMBA team for this great piece of 
software!

Best regards, Jakob