What is the likely cause of these stains?

[Brian_dm]

Those stains are on my ceiling right below my bath tub upstairs. In your experience, what is the likely cause for this?

 

[Rickyman]

A leak from the tub

 

[Brian_dm]

So like piping from the tub and under it?

 

[Jeff Handy]

Could be a leaking tub drain, or drain is rusting out.
Could be water getting past the shower curtain.
Could be water leaking past the caulk at the tub edges, or missing grout at a wall joint.
Could be a drip behind the wall from the tub valve.
The seal on the tub overflow could be bad, and water is splashing onto it then getting behind it.
The escutcheon plate on the tub valve could need caulking, or needs caulking around the tub spout.
The toilet might have overflowed, or the wax seal at the floor is leaking.

 

[Brian_dm]

Here is a pic of the drain. Feels like it needs a seal around it?

 

[Jeff Handy]

How old is that drain?

It looks about fifty years old.

The old seal might just be plumbers putty, which can shrink and crack.
Maybe it is rubber, which also degrades.

Also, the metal edges are corroding, which can let water sneak through.

The trap underneath the tub is probably brass, and that can corrode and perforate also.

You are probably looking at cutting an access hole in the ceiling, under your drain.
Replacing the entire tub drain, then patching the square access hole and trying to match that textured finish.

But for a few months, just leave a plain plywood patch on there, until you know that everything new is staying dry.

This all assumes the leak is from the drain, but consider the rest of my list also.