Re: [PATCH v3 seccomp 1/5] x86: Enable seccomp architecture tracking

Kees Cook
2020-09-30T21:21:34Z

On Wed, Sep 30, 2020 at 10:19:12AM -0500, YiFei Zhu wrote:
> From: Kees Cook <keescook@chromium.org>
>
> 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@chromium.org>
> [YiFei: Removed x32, added macro for nr_syscalls]
> Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>
> ---
> 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..7b3a58271656 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_DEFAULT AUDIT_ARCH_X86_64
> +# define SECCOMP_ARCH_DEFAULT_NR NR_syscalls

bikeshedding: let's call these SECCOMP_ARCH_NATIVE* -- I think it's more
descriptive.

> +# 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_DEFAULT AUDIT_ARCH_I386
> +# define SECCOMP_ARCH_DEFAULT_NR NR_syscalls
> +#endif
> +
> #include <asm-generic/seccomp.h>
>
> #endif /* _ASM_X86_SECCOMP_H */
> --
> 2.28.0
>

But otherwise, yes, looks good to me. For this patch, I think the S-o-b chain is probably more
accurately captured as:

Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: YiFei Zhu <yifeifz2@illinois.edu>
Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>

--
Kees Cook