On Mon, Jun 24, 2024 at 07:53:16AM +0800, Jisheng Zhang wrote: > 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: Jisheng Zhang <jszhang@xxxxxxxxxx> > --- > > since v2: > - add #include <linux/sizes.h> to fixing compiler error found by > Charlie Thanks! Reviewed-by: Charlie Jenkins <charlie@xxxxxxxxxxxx> > > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/thread_info.h | 1 + > arch/riscv/kernel/entry.S | 4 ++++ > drivers/firmware/efi/libstub/Makefile | 3 ++- > 4 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 0525ee2d63c7..9cbfdffec96c 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -118,6 +118,7 @@ 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 > diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h > index 5d473343634b..fca5c6be2b81 100644 > --- a/arch/riscv/include/asm/thread_info.h > +++ b/arch/riscv/include/asm/thread_info.h > @@ -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 > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > index 68a24cf9481a..80ff55a26d13 100644 > --- a/arch/riscv/kernel/entry.S > +++ b/arch/riscv/kernel/entry.S > @@ -130,6 +130,10 @@ 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) > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index 06f0428a723c..3a9521c57641 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -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 > -- > 2.43.0 >
