From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH v3 7/9] vfio: Use driver_override to avert binding to compromising drivers Date: Mon, 26 Jun 2017 13:39:12 -0600 Message-ID: <20170626133912.7746bdfe@w520.home> References: <20170620154312.17487.66916.stgit@gimli.home> <20170620154830.17487.1861.stgit@gimli.home> <20170626090854.GE4902@n2100.armlinux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Greg KH , kvm@vger.kernel.org, eric.auger@redhat.com, linux-kernel@vger.kernel.org To: Russell King - ARM Linux Return-path: In-Reply-To: <20170626090854.GE4902@n2100.armlinux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, 26 Jun 2017 10:08:55 +0100 Russell King - ARM Linux wrote: > On Tue, Jun 20, 2017 at 09:48:31AM -0600, Alex Williamson wrote: > > If a device is bound to a non-vfio, non-whitelisted driver while a > > group is in use, then the integrity of the group is compromised and > > will result in hitting a BUG_ON. This code tries to avoid this case > > by mangling driver_override to force a no-match for the driver. The > > driver-core will either follow-up with a DRIVER_NOT_BOUND (preferred) > > or BOUND_DRIVER, at which point we can remove the driver_override > > mangling. > > Rather than mangling the driver override string to prevent driver binding, > I wonder if it would make more sense to allow the BUS_NOTIFY_BIND_DRIVER > notifier to fail the device probe? > > The driver override strings are, after all, exposed to userspace, and > it strikes me that this kind of mangling is racy - userspace can read > or change the override string at any time. Indeed, that looks easier. I sent and RFC, let's see what Greg has to say. Thanks, Alex