Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport)

From	Matthew Garrett <mjg59@srcf.ucam.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport)
Date	2016-12-02 04:50 +0100
Message-ID	<sJN1f-6yi-1@gated-at.bofh.it> (permalink)
References	<sJyEV-3Or-7@gated-at.bofh.it> <sJyEV-3Or-25@gated-at.bofh.it> <sJB9L-5sv-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thu, Dec 01, 2016 at 04:01:35PM +0100, Greg KH wrote:

> First off, this "secure boot support" massive patchset has not gone
> anywhere yet, so why do this now?

Because David ended up with the short straw when distro maintainers 
talked about this at LPC.

> Secure boot is a trust that the previous boot process is now booting
> your image that it feels is secure (with various levels of "secure").
> It is not about "lock things down so no one can ever touch the hardware
> through different options, except through random logic[1] that we
> somehow trust "more" than configuration options.

If root is able to modify the behaviour of verified code after it was 
verified, then the value of that verification is reduced. Ensuring that 
the code remains trustworthy is vital in a number of security use cases.

> So, what are you really trying to "block" here?  The ability for someone
> to set an i/o port value?  why?  Why does it matter what root sets for
> an irq?  For a dma buffer?  For anything else?  What is preventing this
> going to "secure" somehow?

If root can tell a driver to probe for hardware at a specific address, 
and that driver will then blindly do so, root is trivially able to 
modify arbitrary kernel memory and disable arbitrary security features. 
IRQ or io port attacks are much more difficult to take advantage of, but 
I could imagine that some of them are still plausible.

> Overall, I really don't like this, and honestly, don't like the whole
> "secure boot" patchset either, as it is really a lot of work for
> absolutely no gain that I can see.  Who is "asking" for this type of
> thing, and what are their specific requirements?

Here's an example. The sysfs option to enable module signing is write 
once. If root sets that, root can't unset it. Except there's a whole 
bunch of ways that root *can* unset it, including kexec 
(https://mjg59.dreamwidth.org/28746.html) and a bunch of other things 
that are disabled by this patchset. That feature is entirely useless as 
is. This patchset helps make it useful.

Right now, the secure boot patchset is shipped by basically every single 
mainstream Linux distribution (and a whole bunch that are niche). Right 
now they're having to do extra work to rebase it and ensure that fixes 
get distributed to everyone. There's clearly demand, and Linus has been 
clear that features that are shipped by everyone should just go into 
mainline, so if there are *technical* objections then let's figure them 
out and otherwise just get this stuff merged.

--
Matthew Garrett | mjg59@srcf.ucam.org

Thread

[PATCH 00/39] Annotate hw config module params for future lockdown David Howells <dhowells@redhat.com> - 2016-12-01 13:30 +0100
  [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2016-12-01 13:30 +0100
    Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Greg KH <gregkh@linuxfoundation.org> - 2016-12-01 16:10 +0100
      Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2016-12-01 17:10 +0100
        Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-12-05 22:20 +0100
          Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Greg KH <gregkh@linuxfoundation.org> - 2016-12-06 08:20 +0100
            Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2016-12-06 11:50 +0100
              Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Greg KH <gregkh@linuxfoundation.org> - 2016-12-06 12:00 +0100
      Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Matthew Garrett <mjg59@srcf.ucam.org> - 2016-12-02 04:50 +0100
        Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Greg KH <gregkh@linuxfoundation.org> - 2016-12-02 08:00 +0100
          Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Matthew Garrett <mjg59@srcf.ucam.org> - 2016-12-02 08:20 +0100
            Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-12-05 22:30 +0100
          Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2016-12-02 16:00 +0100
            Re: [PATCH 01/39] Annotate module params that specify hardware  parameters (eg. ioport) Greg KH <gregkh@linuxfoundation.org> - 2016-12-05 16:50 +0100
              Re: [PATCH 01/39] Annotate module params that specify hardware parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2016-12-06 12:00 +0100
  [PATCH 20/39] Annotate hardware config module parameters in  drivers/net/hamradio/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 34/39] Annotate hardware config module parameters in  drivers/watchdog/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 34/39] Annotate hardware config module parameters in  drivers/watchdog/ Guenter Roeck <linux@roeck-us.net> - 2016-12-01 14:00 +0100
  [PATCH 03/39] Annotate hardware config module parameters in  drivers/char/ipmi/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 03/39] Annotate hardware config module parameters in  drivers/char/ipmi/ Corey Minyard <minyard@acm.org> - 2016-12-01 14:20 +0100
  [PATCH 05/39] Annotate hardware config module parameters in  drivers/char/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 28/39] Annotate hardware config module parameters in  drivers/staging/i4l/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 07/39] Annotate hardware config module parameters in  drivers/cpufreq/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 07/39] Annotate hardware config module parameters in drivers/cpufreq/ "Rafael J. Wysocki" <rafael@kernel.org> - 2016-12-01 15:10 +0100
      Re: [PATCH 07/39] Annotate hardware config module parameters in drivers/cpufreq/ David Howells <dhowells@redhat.com> - 2016-12-01 15:20 +0100
        Re: [PATCH 07/39] Annotate hardware config module parameters in drivers/cpufreq/ "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-12-01 15:30 +0100
  [PATCH 39/39] Annotate hardware config module parameters in  sound/pci/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 35/39] Annotate hardware config module parameters in  fs/pstore/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 11/39] Annotate hardware config module parameters in  drivers/input/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 11/39] Annotate hardware config module parameters in  drivers/input/ Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-12-03 20:00 +0100
  [PATCH 21/39] Annotate hardware config module parameters in  drivers/net/irda/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 31/39] Annotate hardware config module parameters in  drivers/staging/vme/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 33/39] Annotate hardware config module parameters in  drivers/video/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 04/39] Annotate hardware config module parameters in  drivers/char/mwave/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 38/39] Annotate hardware config module parameters in  sound/oss/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 06/39] Annotate hardware config module parameters in  drivers/clocksource/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 12/39] Annotate hardware config module parameters in  drivers/isdn/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 23/39] Annotate hardware config module parameters in  drivers/net/wireless/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 23/39] Annotate hardware config module parameters in drivers/net/wireless/ Kalle Valo <kvalo@codeaurora.org> - 2016-12-02 06:10 +0100
      Re: [PATCH 23/39] Annotate hardware config module parameters in drivers/net/wireless/ David Howells <dhowells@redhat.com> - 2016-12-07 14:50 +0100
  [PATCH 29/39] Annotate hardware config module parameters in  drivers/staging/media/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 29/39] Annotate hardware config module parameters in  drivers/staging/media/ Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-12-01 16:00 +0100
      Re: [PATCH 29/39] Annotate hardware config module parameters in drivers/staging/media/ David Howells <dhowells@redhat.com> - 2016-12-01 16:10 +0100
        Re: [PATCH 29/39] Annotate hardware config module parameters in  drivers/staging/media/ Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-12-01 16:20 +0100
  [PATCH 09/39] Annotate hardware config module parameters in  drivers/i2c/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 09/39] Annotate hardware config module parameters in  drivers/i2c/ Jean Delvare <jdelvare@suse.de> - 2016-12-01 14:50 +0100
      Re: [PATCH 09/39] Annotate hardware config module parameters in drivers/i2c/ David Howells <dhowells@redhat.com> - 2016-12-01 15:20 +0100
        Re: [PATCH 09/39] Annotate hardware config module parameters in  drivers/i2c/ Jean Delvare <jdelvare@suse.de> - 2016-12-01 17:10 +0100
        Re: [PATCH 09/39] Annotate hardware config module parameters in  drivers/i2c/ One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-12-05 22:20 +0100
  [PATCH 19/39] Annotate hardware config module parameters in  drivers/net/ethernet/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 18/39] Annotate hardware config module parameters in  drivers/net/can/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 18/39] Annotate hardware config module parameters in  drivers/net/can/ Marc Kleine-Budde <mkl@pengutronix.de> - 2016-12-01 14:10 +0100
  [PATCH 25/39] Annotate hardware config module parameters in  drivers/pci/hotplug/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 25/39] Annotate hardware config module parameters in  drivers/pci/hotplug/ Bjorn Helgaas <helgaas@kernel.org> - 2016-12-07 19:40 +0100
  [PATCH 27/39] Annotate hardware config module parameters in  drivers/scsi/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 27/39] Annotate hardware config module parameters in  drivers/scsi/ Finn Thain <fthain@telegraphics.com.au> - 2016-12-01 23:10 +0100
  [PATCH 26/39] Annotate hardware config module parameters in  drivers/pcmcia/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 08/39] Annotate hardware config module parameters in  drivers/gpio/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 08/39] Annotate hardware config module parameters in  drivers/gpio/ William Breathitt Gray <vilhelm.gray@gmail.com> - 2016-12-01 14:50 +0100
    Re: [PATCH 08/39] Annotate hardware config module parameters in drivers/gpio/ Linus Walleij <linus.walleij@linaro.org> - 2016-12-02 14:00 +0100
  [PATCH 32/39] Annotate hardware config module parameters in  drivers/tty/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 32/39] Annotate hardware config module parameters in  drivers/tty/ Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-12-01 16:10 +0100
  [PATCH 13/39] Annotate hardware config module parameters in  drivers/media/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 36/39] Annotate hardware config module parameters in  sound/drivers/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 17/39] Annotate hardware config module parameters in  drivers/net/arcnet/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 24/39] Annotate hardware config module parameters in  drivers/parport/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 15/39] Annotate hardware config module parameters in  drivers/mmc/host/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 02/39] Annotate hardware config module parameters in  arch/x86/mm/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 16/39] Annotate hardware config module parameters in  drivers/net/appletalk/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 37/39] Annotate hardware config module parameters in  sound/isa/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 30/39] Annotate hardware config module parameters in  drivers/staging/speakup/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 22/39] Annotate hardware config module parameters in  drivers/net/wan/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
  [PATCH 10/39] Annotate hardware config module parameters in  drivers/iio/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100
    Re: [PATCH 10/39] Annotate hardware config module parameters in  drivers/iio/ William Breathitt Gray <vilhelm.gray@gmail.com> - 2016-12-01 15:00 +0100
      Re: [PATCH 10/39] Annotate hardware config module parameters in  drivers/iio/ Jonathan Cameron <jic23@kernel.org> - 2016-12-03 15:40 +0100
        Re: [PATCH 10/39] Annotate hardware config module parameters in drivers/iio/ David Howells <dhowells@redhat.com> - 2016-12-07 14:50 +0100
  [PATCH 14/39] Annotate hardware config module parameters in  drivers/misc/ David Howells <dhowells@redhat.com> - 2016-12-01 13:40 +0100

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