Re: [PATCH 02/11] PCI: Lock down BAR access in secure bootenvironments

From: Pavel Machek
Date: Mon Oct 01 2012 - 17:01:04 EST


On Tue 2012-09-04 11:55:08, Matthew Garrett wrote:
> Any hardware that can potentially generate DMA has to be locked down from
> userspace in order to avoid it being possible for an attacker to cause
> arbitrary kernel behaviour. Default to paranoid - in future we can
> potentially relax this for sufficiently IOMMU-isolated devices.

Would it be possible to

1) Use some better name than CAP_SECURE_FIRMWARE

2) Explain somewhere what the real requirements for "secure" boot are?

"Secure" kernel may not boot unsigned kernel... what does it mean
exactly?

Suppose I launch full-screen window with dosemu running original
windows installation on HDD, accessing raw disks, at nearly native
speed. That is not something kernel should prevent, but it still
allows me to do to do the stuff "secure" boot was designed to
prevent... right?

What is the exact threat "secure" boot should protect us against?

Pavel
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