From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down Date: Wed, 11 Apr 2018 22:33:08 +0200 Message-ID: <20180411203308.GA10167@kroah.com> References: <20180411195436.GA7126@kroah.com> <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> <152346403637.4030.15247096217928429102.stgit@warthog.procyon.org.uk> <12769.1523477356@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <12769.1523477356@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: David Howells Cc: torvalds@linux-foundation.org, linux-man@vger.kernel.org, linux-api@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org List-Id: linux-man@vger.kernel.org On Wed, Apr 11, 2018 at 09:09:16PM +0100, David Howells wrote: > Greg KH 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. thanks, greg k-h