On Fri, Jan 19, 2018 at 07:59:43AM +0000, Matt Redfearn <matt.redfe...@mips.com> wrote:
Hello Matt, > Hi Serge, > > > > On 18/01/18 20:18, Serge Semin wrote: > >On Thu, Jan 18, 2018 at 12:03:03PM -0800, Florian Fainelli > ><f.faine...@gmail.com> wrote: > >>On 01/17/2018 02:23 PM, Serge Semin wrote: > >>>It is useful to have the kernel virtual memory layout printed > >>>at boot time so to have the full information about the booted > >>>kernel. In some cases it might be unsafe to have virtual > >>>addresses freely visible in logs, so the %pK format is used if > >>>one want to hide them. > >>> > >>>Signed-off-by: Serge Semin <fancer.lan...@gmail.com> > >> > >>I personally like having that information because that helps debug and > >>have a quick reference, but there appears to be a trend to remove this > >>in the name of security: > >> > >>https://patchwork.kernel.org/patch/10124007/ > >> > >>maybe hide this behind a configuration option? > > > >Yeah, arm code was the place I picked the function up.) But in my case > >I've used %pK so the pointers would disappear from logging when > >kptr_restrict sysctl is 1 or 2. > >I agree, that we might need to make the printouts optional. If there is > >any kernel config, which for instance increases the kernel security we > >could also use it or anything else to discard the printouts at compile > >time. > > > Certainly, when KASLR is active it would be preferable to hide this > information, so you could use CONFIG_RELOCATABLE. The existing KASLR stuff > additionally hides this kind of information behind CONFIG_DEBUG_KERNEL, so > that only people actively debugging the kernel see it: > > http://elixir.free-electrons.com/linux/v4.15-rc8/source/arch/mips/kernel/setup.c#L604 Ok. I'll hide the printouts behind both of that config macros in the next patchset version. Regards, -Sergey > > Thanks, > Matt > > > > >>-- > >>Florian
