Linking/embedding images on drupal

Wonder if someone can offer any advice on this for me please:

I’ve got a drupal webserver that I’d like to embed images from in a mattermost post. Both mattermost and drupal users are from LDAP, and the drupal link should only work i.e. appear as an embedded image, if the user has permission to access the location on the drupal server where the image is hosted.

On the web client this works as intended - mattermost can obviously reference the cookie for the webserver login and displays (or doesn’t display) as intended. (Assuming the user is or has logged into the webserver this session, but for the purpose of the question, assume they have)

On the desktop client however that doesn’t work. An image that the user has access to won’t show up in the post.

So is there an support, a plugin etc. for mattermost that would let the desktop app pass the creds it has for the user to drupal, log in and retrieve the image? It’s obviously capable of doing that on the web, but not via the desktop app.

Any help appreciated!