From: Guo Ren <[email protected]> The -fstack-protector & -fstack-protector-strong features are from gcc. The patch only add basic kernel support to stack-protector feature and some arch could have its own solution such as ARM64_PTR_AUTH.
After enabling STACKPROTECTOR and STACKPROTECTOR_STRONG, the .text size is expanded from 0x7de066 to 0x81fb32 (only 5%) to add canary checking code. Signed-off-by: Guo Ren <[email protected]> Reviewed-by: Kees Cook <[email protected]> Cc: Paul Walmsley <[email protected]> Cc: Palmer Dabbelt <[email protected]> Cc: Albert Ou <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Björn Töpel <[email protected]> Cc: Greentime Hu <[email protected]> Cc: Atish Patra <[email protected]> --- Change v2: - Fixup rsicv32 compile warning Signed-off-by: Guo Ren <[email protected]> --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/stackprotector.h | 33 +++++++++++++++++++++++++++++++++ arch/riscv/kernel/process.c | 6 ++++++ 3 files changed, 40 insertions(+) create mode 100644 arch/riscv/include/asm/stackprotector.h diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index f927a91..4b0e308 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -63,6 +63,7 @@ config RISCV select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select IRQ_DOMAIN select MODULES_USE_ELF_RELA if MODULES diff --git a/arch/riscv/include/asm/stackprotector.h b/arch/riscv/include/asm/stackprotector.h new file mode 100644 index 00000000..d95f7b2 --- /dev/null +++ b/arch/riscv/include/asm/stackprotector.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _ASM_RISCV_STACKPROTECTOR_H +#define _ASM_RISCV_STACKPROTECTOR_H + +#include <linux/random.h> +#include <linux/version.h> +#include <asm/timex.h> + +extern unsigned long __stack_chk_guard; + +/* + * Initialize the stackprotector canary value. + * + * NOTE: this must only be called from functions that never return, + * and it must always be inlined. + */ +static __always_inline void boot_init_stack_canary(void) +{ + unsigned long canary; + unsigned long tsc; + + /* Try to get a semi random initial value. */ + get_random_bytes(&canary, sizeof(canary)); + tsc = get_cycles(); + canary += tsc + (tsc << BITS_PER_LONG/2); + canary ^= LINUX_VERSION_CODE; + canary &= CANARY_MASK; + + current->stack_canary = canary; + __stack_chk_guard = current->stack_canary; +} +#endif /* _ASM_RISCV_STACKPROTECTOR_H */ diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 824d117..6548929 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -24,6 +24,12 @@ register unsigned long gp_in_global __asm__("gp"); +#ifdef CONFIG_STACKPROTECTOR +#include <linux/stackprotector.h> +unsigned long __stack_chk_guard __read_mostly; +EXPORT_SYMBOL(__stack_chk_guard); +#endif + extern asmlinkage void ret_from_fork(void); extern asmlinkage void ret_from_kernel_thread(void); -- 2.7.4
