Messages in this thread | | | Date | Tue, 12 Feb 2013 22:12:09 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: Lock down MSR writing in secure boot |
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On 02/12/2013 09:39 PM, Matthew Garrett wrote: > On Tue, 2013-02-12 at 16:48 -0800, H. Peter Anvin wrote: > >> OK... what none of this gets into: >> >> Why should CAP_RAWIO be allowed on a secure boot system, when there are >> 2^n known ways of compromise a system with CAP_RAWIO? > > CAP_SYS_RAWIO seems to have ended up being a catchall of "Maybe someone > who isn't entirely root should be able to do this", and not everything > it covers is equivalent to being able to compromise the running kernel. > I wouldn't argue with the idea that maybe we should just reappraise most > of the current uses of CAP_SYS_RAWIO, but removing capability checks > from places that currently have them seems like an invitation for > userspace breakage. >
Sounds like you are thinking of CAP_SYS_ADMIN, but I don't really see a huge difference between MSRs and I/O control registers... just different address spaces.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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