From mboxrd@z Thu Jan 1 00:00:00 1970 From: ramana.radhakrishnan@foss.arm.com (Ramana Radhakrishnan) Date: Fri, 5 Oct 2018 10:01:04 +0100 Subject: [RFC 17/17] arm64: compile the kernel with ptrauth -msign-return-address In-Reply-To: <20181005084754.20950-18-kristina.martsenko@arm.com> References: <20181005084754.20950-1-kristina.martsenko@arm.com> <20181005084754.20950-18-kristina.martsenko@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/10/2018 09:47, Kristina Martsenko wrote: > Compile all functions with two ptrauth instructions: paciasp in the > prologue to sign the return address, and autiasp in the epilogue to > authenticate the return address. This should help protect the kernel > against attacks using return-oriented programming. > > CONFIG_ARM64_PTR_AUTH enables pointer auth for both userspace and the > kernel. > > Signed-off-by: Mark Rutland > Signed-off-by: Kristina Martsenko > --- > arch/arm64/Makefile | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 106039d25e2f..dbcd43ea99d8 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -56,6 +56,10 @@ KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) > KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) > KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) > > +ifeq ($(CONFIG_ARM64_PTR_AUTH),y) > +KBUILD_CFLAGS += -msign-return-address=all Glad to see this being done and being proposed for mainline. I can see why you would prefer this though have you guys experimented at all with -msign-return-address=non-leaf as well ? Orthogonally and just fair warning - the command lines for this are also being revised to provide ROP and JOP protection using BTI from v8.5-a during the GCC-9 timeframe but I suspect that's a different option. regards Ramana Reviewed-by: Ramana Radhakrishnan