Re: What do LSMs *actually* need for checks on notifications?

From: David Howells
Date: Wed Jun 12 2019 - 07:47:53 EST

Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:

> > (6) The security attributes of all the objects between the object in (5)
> > and the object in (4), assuming we work from (5) towards (4) if the
> > two aren't coincident (WATCH_INFO_RECURSIVE).
> Does this apply to anything other than mount notifications?

Not at the moment. I'm considering making it such that you can make a watch
on a keyring get automatically propagated to keys that get added to the
keyring (and removed upon unlink) - the idea being that there is no 'single
parent path' concept for a keyring as there is for a directory.

I'm also pondering the idea of making it possible to have superblock watches
automatically propagated to superblocks created by automount points on the
watched superblock.

> And for mount notifications, isn't the notification actually for a change to
> the mount namespace, not a change to any file?


> Hence, the real "object" for events that trigger mount notifications is the
> mount namespace, right?

Um... arguably. Would that mean that that would need a label from somewhere?

> The watched path is just a way of identifying a subtree of the mount
> namespace for notifications - it isn't the real object being watched.

I like that argument.