None FLOSS license for a logo?

Hello,

I am an upstream maintainer of a GPL-v2-or-later project.

We plan to have our own logo and thinking about how to license this. It 
might come to the case that the logo file (e.g. logo.svg, logo.png, 
logo.ico) won't be licensed with an OSI accepted licence but with a more 
closed license. This is because we don't want to get this logo used in 
other contexts. The logo should be exclusive to the project. I am not 
sure how to achieve this in another way.

To my understanding GNU/Linux Debian is quit strict when it comes to 
free software principles.
Are there any rules or restrictions I need to consider when it comes to 
a situation like this?
Is it even allowed to package such a non-OSI-licensed logo in a 
GNU/Linux Debian package?

If you have another idea how we could achieve our goals please let me 
know.

Best,
Christian Buhtz
https://github.com/bit-team/backintime/issues/215