Messages in this thread | | | Subject | Re: [PATCH V3 03/11] x86: Lock down IO port access when module security is enabled | From | "H. Peter Anvin" <> | Date | Thu, 05 Sep 2013 08:36:51 -0700 |
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Sigh. That capability really is fscked up.
Matthew Garrett <matthew.garrett@nebula.com> wrote: >On Wed, 2013-09-04 at 20:52 -0700, H. Peter Anvin wrote: >> On 09/03/2013 04:50 PM, Matthew Garrett 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. >> > >> > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> >> >> Seriously... just deny CAP_SYS_RAWIO to any system in secure mode. > >No. CAP_SYS_RAWIO blocks things that we don't want blocked (x86 >microcode updates, various disk ioctls, *device firmware uploads* and a >few others) - the semantics just don't match. We could relax those >permissions, but then we'd potentially break someone else's security >considerations.
-- Sent from my mobile phone. Please pardon brevity and lack of formatting.
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