Zinsser Cover Stain is as aggi has mentioned a good one. It's available to brush on or spray. The spray is great if you can contain the overspray and in some cases you can avoid painting the ceiling. Paintable version needs turpentine clean up for the brushes. White spirit doesn't work.
What’s the forum recommended stain blocker/sealer?
I’ve got some yellowing coming through on a ceiling and coving.