Re: [PATCH v3 1/3] uio: add ioctl support

From: Gleb Natapov <gleb@scylladb.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Vlad Zolotarov <vladz@cloudius-systems.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Bruce Richardson <bruce.richardson@intel.com>,
	linux-kernel@vger.kernel.org, hjk@hansjkoch.de,
	avi@cloudius-systems.com, corbet@lwn.net,
	alexander.duyck@gmail.com, gleb@cloudius-systems.com,
	stephen@networkplumber.org
Subject: Re: [PATCH v3 1/3] uio: add ioctl support
Date: Tue, 6 Oct 2015 18:57:37 +0300	[thread overview]
Message-ID: <20151006155736.GB25124@scylladb.com> (raw)
In-Reply-To: <20151006181610-mutt-send-email-mst@redhat.com>

On Tue, Oct 06, 2015 at 06:19:34PM +0300, Michael S. Tsirkin wrote:
> On Tue, Oct 06, 2015 at 05:30:31PM +0300, Gleb Natapov wrote:
> > On Tue, Oct 06, 2015 at 05:19:22PM +0300, Michael S. Tsirkin wrote:
> > > On Tue, Oct 06, 2015 at 11:33:56AM +0300, Vlad Zolotarov wrote:
> > > > the solution u propose should be a matter of a separate patch and is
> > > > obviously orthogonal to this series.
> > > 
> > > Doesn't work this way, sorry. You want a patch enabling MSI merged,
> > > you need to secure the MSI configuration.
> > > 
> > MSI can be enabled right now without the patch by writing directly into
> > PCI bar.
> 
> By poking at config registers in sysfs? We can block this, or we
> can log this, pretty easily. We don't ATM but it's not hard to do.
> 
Blocking this will break userspace API. As a maintainer you should know
that we do not break userspace APIs. Logging this is fine, but how
exactly it helps you with "security"? The patch in question already
taints the kernel which is much stronger than logging.

> > The only thing this patch adds is forwarding the interrupt to
> > an eventfd.
> 
> This one just adds a bunch of ioctls. The next ones do
> more than you describe.
> 
Yes, it adds bunch of ioctls to do exactly what I wrote above. What
point have you tried to make by this statement? It eluded me.

--
			Gleb.