Unverified Commit b5db73fb authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Palmer Dabbelt
Browse files

riscv: enable HAVE_ARCH_STACKLEAK 



Add support for the stackleak feature. Whenever the kernel returns to user
space the kernel stack is filled with a poison value.

At the same time, disables the plugin in EFI stub code because EFI stub
is out of scope for the protection.

Tested on qemu and milkv duo:
/ # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
[   38.675575] lkdtm: Performing direct entry STACKLEAK_ERASING
[   38.678448] lkdtm: stackleak stack usage:
[   38.678448]   high offset: 288 bytes
[   38.678448]   current:     496 bytes
[   38.678448]   lowest:      1328 bytes
[   38.678448]   tracked:     1328 bytes
[   38.678448]   untracked:   448 bytes
[   38.678448]   poisoned:    14312 bytes
[   38.678448]   low offset:  8 bytes
[   38.689887] lkdtm: OK: the rest of the thread stack is properly erased

Signed-off-by: default avatarJisheng Zhang <jszhang@kernel.org>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20240623235316.2010-1-jszhang@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 1d20e5d4

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -123,6 +123,7 @@ config RISCV 
	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT

	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_STACKLEAK

	select HAVE_ARCH_THREAD_STRUCT_WHITELIST

	select HAVE_ARCH_TRACEHOOK

	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU

arch/riscv/include/asm/thread_info.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 


#include <asm/page.h>

#include <linux/const.h>

#include <linux/sizes.h>



/* thread information allocation */

#define THREAD_SIZE_ORDER	CONFIG_THREAD_SIZE_ORDER

arch/riscv/kernel/entry.S

+4 −0
Original line number Diff line number Diff line
@@ -133,6 +133,10 @@ SYM_CODE_START_NOALIGN(ret_from_exception) 
#endif

	bnez s0, 1f



#ifdef CONFIG_GCC_PLUGIN_STACKLEAK

	call	stackleak_erase_on_task_stack

#endif



	/* Save unwound kernel stack pointer in thread_info */

	addi s0, sp, PT_SIZE_ON_STACK

	REG_S s0, TASK_TI_KERNEL_SP(tp)

drivers/firmware/efi/libstub/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -28,7 +28,8 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \ 
				   -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \

				   -DEFI_HAVE_STRCMP -fno-builtin -fpic \

				   $(call cc-option,-mno-single-pic-base)

cflags-$(CONFIG_RISCV)		+= -fpic -DNO_ALTERNATIVE -mno-relax

cflags-$(CONFIG_RISCV)		+= -fpic -DNO_ALTERNATIVE -mno-relax \

				   $(DISABLE_STACKLEAK_PLUGIN)

cflags-$(CONFIG_LOONGARCH)	+= -fpie



cflags-$(CONFIG_EFI_PARAMS_FROM_FDT)	+= -I$(srctree)/scripts/dtc/libfdt