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From:   David Howells <dhowells@redhat.com>
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To:     Jann Horn <jannh@google.com>
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Subject: Re: An actual suggestion (Re: [GIT PULL] Kernel lockdown for secure boot)
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Date:   Wed, 04 Apr 2018 23:19:27 +0100
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Jann Horn <jannh@google.com> wrote:

> > Uh, no.  bpf, for example, can be used to modify kernel memory.
> 
> I'm pretty sure bpf isn't supposed to be able to modify arbitrary
> kernel memory. AFAIU if you can use BPF to write to arbitrary kernel
> memory, that's a bug; with CAP_SYS_ADMIN, you can read from userspace,
> write to userspace, and read from kernelspace, but you shouldn't be
> able to write to kernelspace.

Ah - you may be right.  I seem to have misremembered what Joey Lee wrote in
his patch description.

David