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 > > Vivek Goyal <vgoyal at redhat.com> wrote: > >On Mon, Dec 09, 2013 at 05:06:10PM -0800, Kees Cook wrote: > >> On Mon, Dec 9, 2013 at 4:34 PM, H. Peter Anvin <hpa at zytor.com> wrote: > >> > On 12/09/2013 04:16 PM, Kees Cook wrote: > >> >> For general-purpose (i.e. distro) kernel builds it makes sense to > >build with > >> >> CONFIG_KEXEC to allow end users to choose what kind of things they > >want to do > >> >> with kexec. However, in the face of trying to lock down a system > >with such > >> >> a kernel, there needs to be a way to disable kexec (much like > >module loading > >> >> can be disabled). Without this, it is too easy for the root user > >to modify > >> >> kernel memory even when CONFIG_STRICT_DEVMEM and modules_disabled > >are set. > >> >> > >> >> Signed-off-by: Kees Cook <keescook at chromium.org> > >> >> Acked-by: Rik van Riel <riel at redhat.com> > >> > > >> > So the logic is to load a crashkernel and then lock down the > >machine > >> > before services, networking etc. are enabled? > >> > >> Right, or to just turn it off at boot time if kexec will not be used > >at all. > > > >kdump kernel is loaded with the help of kdump service. Different > >distro's > >might have different dependencies for that serivce. But recently in > >fedora > >we wait network to come up before starting that service. (So that nfs > >targets can be mounted and checked for valid dump destinations). > > > >IOW, crash kernel is loaded quite late in the game (quite a few > >services > >have run and possibly networking is up too). To me, practically one > >will > >disable kdump also if you change state of this knob early. > > > >Thanks > >Vivek > > -- > Sent from my mobile phone. Please pardon brevity and lack of formatting.
