On Wed, Apr 11, 2018 at 1:33 PM, Greg KH <g...@kroah.com> wrote: > On Wed, Apr 11, 2018 at 09:09:16PM +0100, David Howells wrote: >> Greg KH <g...@kroah.com> wrote: >> >> > Why not just disable debugfs entirely? This half-hearted way to sorta >> > lock it down is odd, it is meant to not be there at all, nothing in your >> > normal system should ever depend on it. >> > >> > So again just don't allow it to be mounted at all, much simpler and more >> > obvious as to what is going on. >> >> Yeah, I agree - and then I got complaints because it seems that it's been >> abused to allow drivers and userspace components to communicate. > > With in-kernel code? Please let me know and I'll go fix it up to not > allow that, as that is not ok. > > I do know of some bad examples of out-of-tree code abusing debugfs to do > crazy things (battery level monitoring?), but that's their own fault... > > debugfs is for DEBUGGING! For anything you all feel should be "secure", > then just disable it entirely. >
Debugfs is very, very useful for, ahem, debugging. I really think this is an example of why we should split lockdown into the read and write varieties and allow mounting and reading debugfs when only write is locked down.