Re: [PATCH v4 seccomp 3/5] x86: Enable seccomp architecture tracking

[Andy Lutomirski]

On Fri, Oct 9, 2020 at 10:15 AM YiFei Zhu <zhuyifei1999@xxxxxxxxx> wrote:
>
> From: Kees Cook <keescook@xxxxxxxxxxxx>
>
> Provide seccomp internals with the details to calculate which syscall
> table the running kernel is expecting to deal with. This allows for
> efficient architecture pinning and paves the way for constant-action
> bitmaps.
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Co-developed-by: YiFei Zhu <yifeifz2@xxxxxxxxxxxx>
> Signed-off-by: YiFei Zhu <yifeifz2@xxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/seccomp.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/arch/x86/include/asm/seccomp.h b/arch/x86/include/asm/seccomp.h
> index 2bd1338de236..03365af6165d 100644
> --- a/arch/x86/include/asm/seccomp.h
> +++ b/arch/x86/include/asm/seccomp.h
> @@ -16,6 +16,18 @@
>  #define __NR_seccomp_sigreturn_32      __NR_ia32_sigreturn
>  #endif
>
> +#ifdef CONFIG_X86_64
> +# define SECCOMP_ARCH_NATIVE           AUDIT_ARCH_X86_64
> +# define SECCOMP_ARCH_NATIVE_NR                NR_syscalls
> +# ifdef CONFIG_COMPAT
> +#  define SECCOMP_ARCH_COMPAT          AUDIT_ARCH_I386
> +#  define SECCOMP_ARCH_COMPAT_NR       IA32_NR_syscalls
> +# endif
> +#else /* !CONFIG_X86_64 */
> +# define SECCOMP_ARCH_NATIVE           AUDIT_ARCH_I386
> +# define SECCOMP_ARCH_NATIVE_NR                NR_syscalls
> +#endif

Is the idea that any syscall that's out of range for this (e.g. all of
the x32 syscalls) is unoptimized?  I'm okay with this, but I think it
could use a comment.

> +
>  #include <asm-generic/seccomp.h>
>
>  #endif /* _ASM_X86_SECCOMP_H */
> --
> 2.28.0
>


-- 
Andy Lutomirski
AMA Capital Management, LLC