Re: [GIT PULL] Kernel lockdown for secure boot

[joeyli]

On Sun, Apr 08, 2018 at 08:40:10PM -0700, Alexei Starovoitov wrote:
> On Sun, Apr 08, 2018 at 04:07:42PM +0800, joeyli wrote:
> > 
> > > If the only thing that folks are paranoid about is reading
> > > arbitrary kernel memory with bpf_probe_read() helper
> > > then preferred patch would be to disable it during verification
> > > when in lockdown mode
> > 
> > Sorry for I didn't fully understand your idea...
> > Do you mean that using bpf verifier to filter out bpf program that
> > uses bpf_probe_read()?
> 
> Take a look bpf_get_trace_printk_proto().
> Similarly we can add bpf_get_probe_read_proto() that
> will return NULL if lockdown is on.
> Then programs with bpf_probe_read() will be rejected by the verifier.
> 

OK, I saw check_helper_call(). Thank you for point it out.
it's good idea!

Joey Lee