Messages in this thread | | | Date | Fri, 12 Jun 2020 18:46:02 +0200 | From | Borislav Petkov <> | Subject | Re: [RFC PATCH] x86/msr: Filter MSR writes |
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On Fri, Jun 12, 2020 at 09:34:06AM -0700, Sean Christopherson wrote: > The kernel should be tainted if the WRMSR is attempted, regardless of > whether it succeeds, and it should happen before the WRMSR. E.g. pointing > MSR_IA32_DS_AREA at a bad address will likely cause an OOPS on the #PF
If the MSR write fails, MSR_IA32_DS_AREA won't have the bad address. If the writes fail, nothing has been changed.
> This can be 0600, or maybe 0644, i.e. allow the user to enable/disable > writes after the module has been loaded.
What for?
crw------- 1 root root 202, 0 Jun 10 19:54 /dev/cpu/0/msr
You need root to write to the chrdev.
Also, the intent is *not* to open it more but to close it so that the incentive to design proper interfaces is there.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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