An actual suggestion (Re: [GIT PULL] Kernel lockdown for secure boot)

joeyli jlee at
Thu Apr 5 01:48:20 UTC 2018

On Wed, Apr 04, 2018 at 11:19:27PM +0100, David Howells wrote:
> Jann Horn <jannh at> 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.

Sorry for it's my fault to misunderstood the behavoir of bpf with

Joey Lee
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