Date: Mon, 4 Dec 2017 10:19:26 -0800 From: Kees Cook <keescook@...omium.org> To: Will Deacon <will.deacon@....com> Cc: Andrew Morton <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com, Mark Rutland <mark.rutland@....com>, Laura Abbott <labbott@...hat.com>, X86 ML <x86@...nel.org> Subject: Re: [PATCH] Kconfig: Make STRICT_DEVMEM default-y on x86 and arm64 On Mon, Dec 4, 2017 at 7:56 AM, Will Deacon <will.deacon@....com> wrote: > On Fri, Dec 01, 2017 at 12:10:00PM -0800, Kees Cook wrote: >> Distros have been shipping with CONFIG_STRICT_DEVMEM=y for years now. It >> is probably time to flip this default for x86 and arm64. > > Should we be defaulting IO_STRICT_DEVMEM on as well? I'd love to see that, but I haven't seen a long history on this setting yet. It may be that arm64 can do it, since it doesn't have the x86 hardware legacy stuff ... If you're willing to give it a shot, I'm all for it. :) -Kees > > Will > >> Signed-off-by: Kees Cook <keescook@...omium.org> >> --- >> lib/Kconfig.debug | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug >> index 947d3e2ed5c2..39b123d04a36 100644 >> --- a/lib/Kconfig.debug >> +++ b/lib/Kconfig.debug >> @@ -1985,7 +1985,7 @@ config STRICT_DEVMEM >> bool "Filter access to /dev/mem" >> depends on MMU && DEVMEM >> depends on ARCH_HAS_DEVMEM_IS_ALLOWED >> - default y if TILE || PPC >> + default y if TILE || PPC || X86 || ARM64 >> ---help--- >> If this option is disabled, you allow userspace (root) access to all >> of memory, including kernel and userspace memory. Accidental >> -- >> 2.7.4 >> >> >> -- >> Kees Cook >> Pixel Security -- Kees Cook Pixel Security
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