Re: [PATCH 09/39] Annotate hardware config module parameters in drivers/i2c/

From	Jean Delvare <jdelvare@suse.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 09/39] Annotate hardware config module parameters in drivers/i2c/
Date	2016-12-01 17:10 +0100
Message-ID	<sJC5P-6gw-5@gated-at.bofh.it> (permalink)
References	<sJzUl-4u2-5@gated-at.bofh.it> <sJyEV-3Or-7@gated-at.bofh.it> <sJyOC-3S3-57@gated-at.bofh.it> <sJAno-4Xx-15@gated-at.bofh.it>
Organization	Suse Linux

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On jeu., 2016-12-01 at 14:12 +0000, David Howells wrote:
> Jean Delvare <jdelvare@suse.de> wrote:
> 
> > > Note that we do still need to do the module initialisation because some
> > > drivers have viable defaults set in case parameters aren't specified and
> > > some drivers support automatic configuration (e.g. PNP or PCI) in addition
> > > to manually coded parameters.
> > 
> > Initializing the driver when you are not able to honor the user request
> > looks wrong to me. I don't see how some drivers having sane defaults
> > justifies that. Using the defaults when no parameters are passed is one
> > thing (good), still using the defaults when parameters are passed is
> > another (bad), and you should be able to differentiate between these two
> > cases.
> 
> Corey Minyard argues the other way:
> 
> 	This would prevent any IPMI interface from working if any address was
> 	given on the kernel command line. I'm not sure what the best policy
> 	is, but that sounds like a possible DOS to me.
> 
> Your preference allows someone to prevent a driver from initialising - which
> could also be bad.  The problem is that I don't think there's any way to do
> both.

I'm not sure what is your threat model, but I'm afraid that if the
attacker can change the kernel command line, he/she has so many ways to
screw up the machine, that removing one won't make a difference.

>> (...)
> > And maybe the following ones, but I'm not sure if forcibly enabling a
> > device is part of what you need to prevent:
> > 
> > i2c-piix4.c:module_param (force, int, 0);
> > i2c-sis630.c:module_param(force, bool, 0);
> > i2c-viapro.c:module_param(force, bool, 0);
> 
> I don't know either.  One could argue it *should* be locked down because its
> need appears to reflect a BIOS bug.

Indeed. OTOH if you remove all kernel code that is there solely due to
BIOS bugs, then you can rename Secure Boot to No Boot. Well that's
certainly one way to be secure ;-)

-- 
Jean Delvare
SUSE L3 Support

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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