diff options
| author | Jinjie Ruan <ruanjinjie@huawei.com> | 2024-07-20 22:40:58 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2024-07-20 22:40:58 +0800 |
| commit | a0f7085f6a63f19f83f2644ce2da49a8d3cf7c0f (patch) | |
| tree | 646a6b07f4a6de409ee4b11bb129f8d84ccd3197 | |
| parent | 08f417db702c5b05150b3851af7186fee96ddd46 (diff) | |
LoongArch: Add RANDOMIZE_KSTACK_OFFSET support
Add support of kernel stack offset randomization while handling syscall,
the offset is defaultly limited by KSTACK_OFFSET_MAX().
In order to avoid triggering stack canaries (due to __builtin_alloca())
and slowing down the entry path, use __no_stack_protector attribute to
disable stack protector for do_syscall() at function level.
With this patch, the REPORT_STACK test show that:
`loongarch64 bits of stack entropy: 7`
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
| -rw-r--r-- | arch/loongarch/Kconfig | 1 | ||||
| -rw-r--r-- | arch/loongarch/kernel/syscall.c | 22 |
2 files changed, 22 insertions, 1 deletions
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index ddc042895d01..fcf6451b4e38 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -106,6 +106,7 @@ config LOONGARCH select HAVE_ARCH_KFENCE select HAVE_ARCH_KGDB if PERF_EVENTS select HAVE_ARCH_MMAP_RND_BITS if MMU + select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET select HAVE_ARCH_SECCOMP select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK diff --git a/arch/loongarch/kernel/syscall.c b/arch/loongarch/kernel/syscall.c index ec17cd5163b7..ba5d0930a74f 100644 --- a/arch/loongarch/kernel/syscall.c +++ b/arch/loongarch/kernel/syscall.c @@ -9,11 +9,14 @@ #include <linux/entry-common.h> #include <linux/errno.h> #include <linux/linkage.h> +#include <linux/objtool.h> +#include <linux/randomize_kstack.h> #include <linux/syscalls.h> #include <linux/unistd.h> #include <asm/asm.h> #include <asm/exception.h> +#include <asm/loongarch.h> #include <asm/signal.h> #include <asm/switch_to.h> #include <asm-generic/syscalls.h> @@ -39,7 +42,7 @@ void *sys_call_table[__NR_syscalls] = { typedef long (*sys_call_fn)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); -void noinstr do_syscall(struct pt_regs *regs) +void noinstr __no_stack_protector do_syscall(struct pt_regs *regs) { unsigned long nr; sys_call_fn syscall_fn; @@ -55,11 +58,28 @@ void noinstr do_syscall(struct pt_regs *regs) nr = syscall_enter_from_user_mode(regs, nr); + add_random_kstack_offset(); + if (nr < NR_syscalls) { syscall_fn = sys_call_table[nr]; regs->regs[4] = syscall_fn(regs->orig_a0, regs->regs[5], regs->regs[6], regs->regs[7], regs->regs[8], regs->regs[9]); } + /* + * This value will get limited by KSTACK_OFFSET_MAX(), which is 10 + * bits. The actual entropy will be further reduced by the compiler + * when applying stack alignment constraints: 16-bytes (i.e. 4-bits) + * aligned, which will remove the 4 low bits from any entropy chosen + * here. + * + * The resulting 6 bits of entropy is seen in SP[9:4]. + */ + choose_random_kstack_offset(drdtime()); + syscall_exit_to_user_mode(regs); } + +#ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET +STACK_FRAME_NON_STANDARD(do_syscall); +#endif |