From: Rajat Jain <rajatxjain@gmail.com>
To: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rajat Jain <rajatja@google.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Krishnakumar,
Lalithambika" <lalithambika.krishnakumar@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci <linux-pci@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Prashant Malani <pmalani@google.com>,
Benson Leung <bleung@google.com>, Todd Broch <tbroch@google.com>,
Alex Levin <levinale@google.com>,
Mattias Nissler <mnissler@google.com>,
Zubin Mithra <zsm@google.com>,
Bernie Keany <bernie.keany@intel.com>,
Aaron Durbin <adurbin@google.com>,
Diego Rivas <diegorivas@google.com>,
Duncan Laurie <dlaurie@google.com>,
Furquan Shaikh <furquan@google.com>,
Jesse Barnes <jsbarnes@google.com>,
Christian Kellner <christian@kellner.me>,
Alex Williamson <alex.williamson@redhat.com>,
Joerg Roedel <joro@8bytes.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] Restrict the untrusted devices, to bind to only a set of "whitelisted" drivers
Date: Wed, 10 Jun 2020 12:57:00 -0700 [thread overview]
Message-ID: <CAA93t1r37y-Shr+-oHoBoLSbE1vAguwdE2ak2F6L4Ecm5+3JKQ@mail.gmail.com> (raw)
In-Reply-To: <CAOSf1CGMwHGSn18MeKYr2BESfLwq3Q8_0fC6yhiQRrAXeSosqQ@mail.gmail.com>
On Tue, Jun 9, 2020 at 6:34 PM Oliver O'Halloran <oohall@gmail.com> wrote:
>
> On Wed, Jun 10, 2020 at 7:04 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> >
> > To sketch this out, my understanding of how this would work is:
> >
> > - Expose the PCI pdev->untrusted bit in sysfs. We don't expose this
> > today, but doing so would be trivial. I think I would prefer a
> > sysfs name like "external" so it's more descriptive and less of a
> > judgment.
> >
> > This comes from either the DT "external-facing" property or the
> > ACPI "ExternalFacingPort" property.
>
> I don't think internal / external is the right distinction to be
> making. We have a similar trust issue with the BMC in servers even
> though they're internal devices. They're typically network accessible
> and infrequently updated so treating them as trustworthy isn't a great
> idea. We have been slowly de-privileging the BMC over the last few
> years, but the PCIe interface isn't locked down enough for my liking
> since the SoCs we use do allow software to set the VDID and perform
> arbitrary DMAs (thankfully limited to 32bit). If we're going to add in
> infrastructure for handling possibly untrustworthy PCI devices then
> I'd like to use that for BMCs too.
>
> > - All devices present at boot are enumerated. Any statically built
> > drivers will bind to them before any userspace code runs.
> >
> > If you want to keep statically built drivers from binding, you'd
> > need to invent some mechanism so pci_driver_init() could clear
> > drivers_autoprobe after registering pci_bus_type.
> >
> > - Early userspace code prevents modular drivers from automatically
> > binding to PCI devices:
> >
> > echo 0 > /sys/bus/pci/drivers_autoprobe
> >
> > This prevents modular drivers from binding to all devices, whether
> > present at boot or hot-added.
>
> I don't see why this is preferable to just disabling autoprobe for
> untrusted devices. That would dovetail nicely with Rajat's whitelist
> idea if we want to go down that route and I think we might want to.
> The BMC usually provides some form of VGA console and we'd like that
> to continue working out-of-the-box without too much user (or distro)
> intervention.
I wouldn't mind introducing a kernel parameter to disable auto-probing
of untrusted devices if there is a wider agreement here.
The only notch is that in my opinion, if present, that parameter
should disable auto-probing for "external" devices only (i.e.
"external-facing" devices should still be auto-probed).
Thanks,
Rajat
>
> Oliver
next prev parent reply other threads:[~2020-06-10 19:57 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 23:07 [RFC] Restrict the untrusted devices, to bind to only a set of "whitelisted" drivers Rajat Jain
2020-05-04 11:47 ` Jean-Philippe Brucker
2020-05-04 11:59 ` Jean-Philippe Brucker
2020-05-04 19:17 ` Rajat Jain
2020-05-05 12:33 ` Mika Westerberg
2020-05-06 18:51 ` Rajat Jain
2020-05-11 20:31 ` Rajat Jain
2020-05-13 15:19 ` Bjorn Helgaas
2020-05-13 21:26 ` Rajat Jain
2020-05-14 13:42 ` Mika Westerberg
2020-05-14 19:12 ` Raj, Ashok
2020-05-15 2:18 ` Rajat Jain
2020-05-26 16:30 ` Rajat Jain
2020-06-01 23:25 ` Bjorn Helgaas
2020-06-02 5:06 ` Greg Kroah-Hartman
2020-06-03 2:27 ` Rajat Jain
2020-06-03 6:07 ` Greg Kroah-Hartman
2020-06-03 11:51 ` Rajat Jain
2020-06-03 12:16 ` Greg Kroah-Hartman
2020-06-03 12:57 ` Rajat Jain
2020-06-03 13:29 ` Greg Kroah-Hartman
2020-06-04 19:38 ` Rajat Jain
2020-06-05 8:02 ` Greg Kroah-Hartman
2020-06-06 1:08 ` Rajat Jain
2020-06-07 11:36 ` Greg Kroah-Hartman
2020-06-08 17:03 ` Jesse Barnes
2020-06-08 17:50 ` Greg Kroah-Hartman
2020-06-08 18:29 ` Jesse Barnes
2020-06-08 18:41 ` Rajat Jain
2020-06-09 9:54 ` Greg Kroah-Hartman
2020-06-30 21:46 ` Pavel Machek
2020-06-09 5:57 ` Greg Kroah-Hartman
2020-06-30 21:45 ` Pavel Machek
2020-07-01 6:54 ` Greg Kroah-Hartman
2020-07-01 8:47 ` Pavel Machek
2020-07-01 10:57 ` Greg Kroah-Hartman
2020-07-01 11:08 ` Pavel Machek
2020-06-09 21:04 ` Bjorn Helgaas
2020-06-09 23:23 ` Rajat Jain
2020-06-10 0:04 ` Bjorn Helgaas
2020-06-10 0:30 ` Rajat Jain
2020-06-10 20:17 ` Rajat Jain
2020-06-10 23:09 ` Bjorn Helgaas
2020-06-10 23:01 ` Bjorn Helgaas
2020-06-10 23:46 ` Rajat Jain
2020-06-10 7:13 ` Greg Kroah-Hartman
2020-06-10 1:34 ` Oliver O'Halloran
2020-06-10 19:57 ` Rajat Jain [this message]
2020-06-16 1:24 ` Rajat Jain
2020-06-10 7:12 ` Greg Kroah-Hartman
2020-05-15 12:44 ` Joerg Roedel
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