Re: [PATCH 03/11] x86: Lock down IO port access in secure bootenvironments

From: Alan Cox
Date: Tue Sep 04 2012 - 12:11:11 EST


On Tue, 4 Sep 2012 11:55:09 -0400
Matthew Garrett <mjg@xxxxxxxxxx> wrote:

> IO port access would permit users to gain access to PCI configuration
> registers, which in turn (on a lot of hardware) give access to MMIO register
> space. This would potentially permit root to trigger arbitrary DMA, so lock
> it down by default.

You've missed a load of others, all over the kernel, let alone getting
into devices with other paths to firmware reprogramming of which there
are many.

You need to enforce signing on request_firmware for example, and sign
every firmware.


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