Re: [PATCH 25/39] Annotate hardware config module parameters in drivers/pci/hotplug/

From: Bjorn Helgaas
Date: Wed Dec 07 2016 - 13:35:04 EST


On Thu, Dec 01, 2016 at 12:32:58PM +0000, David Howells wrote:
> When the kernel is running in secure boot mode, we lock down the kernel to
> prevent userspace from modifying the running kernel image. Whilst this
> includes prohibiting access to things like /dev/mem, it must also prevent
> access by means of configuring driver modules in such a way as to cause a
> device to access or modify the kernel image.
>
> To this end, annotate module_param* statements that refer to hardware
> configuration and indicate for future reference what type of parameter they
> specify. The parameter parser in the core sees this information and can
> skip such parameters with an error message if the kernel is locked down.
> The module initialisation then runs as normal, but just sees whatever the
> default values for those parameters is.
>
> 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.
>
> This patch annotates drivers in drivers/pci/hotplug/.
>
> Suggested-by: One Thousand Gnomes <gnomes@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Scott Murray <scott@xxxxxxxxxxxx>
> cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> cc: linux-pci@xxxxxxxxxxxxxxx

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

I assume you'll merge this via some non-PCI tree. Let me know if you
need anything else from me.

> ---
>
> drivers/pci/hotplug/cpcihp_generic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/hotplug/cpcihp_generic.c b/drivers/pci/hotplug/cpcihp_generic.c
> index 88a44a707b96..bbf9cf8aeaad 100644
> --- a/drivers/pci/hotplug/cpcihp_generic.c
> +++ b/drivers/pci/hotplug/cpcihp_generic.c
> @@ -220,7 +220,7 @@ module_param(first_slot, byte, 0);
> MODULE_PARM_DESC(first_slot, "Hotswap bus first slot number");
> module_param(last_slot, byte, 0);
> MODULE_PARM_DESC(last_slot, "Hotswap bus last slot number");
> -module_param(port, ushort, 0);
> +module_param_hw(port, ushort, ioport, 0);
> MODULE_PARM_DESC(port, "#ENUM signal I/O port");
> module_param(enum_bit, uint, 0);
> MODULE_PARM_DESC(enum_bit, "#ENUM signal bit (0-7)");
>
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