riscv: Add STACKPROTECTOR supported

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 <guoren@linux.alibaba.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Guo Ren 2020-07-10 16:19:57 +00:00 committed by Palmer Dabbelt
parent 08b5985e7b
commit f2c9699f65
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
3 changed files with 40 additions and 0 deletions

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@ -66,6 +66,7 @@ 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

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@ -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 */

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@ -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);