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Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed

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On Mon, Nov 21, 2016 at 11:10:52PM +0000, David Howells wrote:
> One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> wrote:
> 
> > You need to filter or lock down kernel module options because a lot of
> > modules let you set the I/O port or similar (eg mmio) which means you can
> > hack the entire machine with say the 8250 driver just by using it with an
> > mmio of the right location to patch the secure state to zero just by
> > getting the ability to write to the modules conf file.
> 
> Is the attached patch the right sort of idea?  [Note that I haven't actually
> compiled most of these drivers to check my changes yet.]
> 
> David
> ---
> commit 8613a9655dad98c3358d82a9c4310cebdcb852ae
> Author: David Howells <dhowells@redhat.com>
> Date:   Mon Nov 21 22:43:27 2016 +0000
> 
>     Lock down drivers that can have io ports, io mem, irqs and dma changed
>     
>     Lock down drivers that can have io ports, io mem, irqs and dma channels
>     changed so that they can't be used to cause hardware to access the kernel
>     image.
>     
>     Notes:
>     
>      (1) module_isa_driver() gets an extra parameter that, if true, will cause
>          the module load to be rejected if the kernel is locked down.
>     
>      (2) module_driver() calls module_lockdown_check() to ask if the module
>          load should be rejected if the kernel is locked down.  This is a macro
>          that should be #undef'd and then redefined right before
>          module_driver() is called.
>     
>      (3) module_pci_driver() is a wrapper around module_driver(), so the same
>          macro is used as in (2).
>     
>      (4) A number of drivers use parport 'ports' - so I haven't touched those.

You might also need to disable CIS overrides and CIS firmware loading for PCMCIA
drivers, I presume. That needs two changes:

	- Abort in drivers/pcmcia/ds.c::pcmcia_load_firmware() or disable
	  the CONFIG_PCMCIA_LOAD_CIS config option permanently.

	- Abort in drivers/pcmcia/cistpl.c::pccard_store_cis() or remove
	  write access to the "cis" file in
	  drivers/pcmcia/cistpl.c::pccard_cis_attr

Best,
	Dominik

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[PATCH 00/16] Kernel lockdown David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 15/16] acpi: Ignore acpi_rsdp kernel param when the kernel  has been locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
    Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-17 23:00 +0100
      Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Josh Boyer <jwboyer@fedoraproject.org> - 2016-11-18 13:00 +0100
        Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-18 13:20 +0100
      Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit David Howells <dhowells@redhat.com> - 2016-11-18 18:30 +0100
  [PATCH 07/16] kexec: Disable at runtime if the kernel is locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 08/16] Copy secure_boot flag in boot params across kexec  reboot David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 12/16] ACPI: Limit access to custom_method when the kernel  is locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 03/16] efi: Disable secure boot if shim is in insecure mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 04/16] efi: Lock down the kernel if booted in secure boot  mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 11/16] x86: Lock down IO port access when the kernel is  locked down David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 06/16] Add a sysrq option to exit secure boot mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  Re: [PATCH 00/16] Kernel lockdown One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-11-16 23:30 +0100
    Re: [PATCH 00/16] Kernel lockdown Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-21 21:00 +0100
  Re: [PATCH 00/16] Kernel lockdown Justin Forbes <jmforbes@linuxtx.org> - 2016-11-16 23:30 +0100
  Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-22 07:30 +0100
    Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed David Howells <dhowells@redhat.com> - 2016-11-23 14:00 +0100
      Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-23 20:30 +0100
        Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed David Howells <dhowells@redhat.com> - 2016-11-24 18:40 +0100
          Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-24 21:30 +0100

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