Re: [PATCH v2] kexec: add sysctl to disable kexec

Vivek Goyal
2013-12-10T19:15:06Z

On Tue, Dec 10, 2013 at 10:54:00AM -0800, H. Peter Anvin wrote:
> On 12/10/2013 10:33 AM, Vivek Goyal wrote:
> > On Tue, Dec 10, 2013 at 08:32:38AM -0800, H. Peter Anvin wrote:
> >> Of course it isn't.
> >
> > I am not sure what are you trying to say. This is too brief.
> >
> > Thanks
> > Vivek
> >
>
> Of course it is not sufficient. Once you can get arbitrary code into
> kernel space (CPL 0) you can do anything, and "disabling jump back" is
> just a speed bump.

Agreed that disabling jump back is only a speed bump.

Kees, so how would be use this knob?

- If I put it in some init script, then root will permission to modify
and remove it.

- Can one specify sysctl parameters on command line? If yes, then one
can disable this using kernel command line and in that case kdump will
be disabled too.

Thanks
Vivek