linux-kernel - Re: [PATCH seccomp 3/8] powerpc: Enable seccomp architecture tracking

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Message-ID: <87wnz1to9n.fsf@mpe.ellerman.id.au>
Date:   Wed, 04 Nov 2020 21:22:28 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     YiFei Zhu <zhuyifei1999@...il.com>,
        containers@...ts.linux-foundation.org
Cc:     linux-sh@...r.kernel.org, Tobin Feldman-Fitzthum <tobin@....com>,
        Hubertus Franke <frankeh@...ibm.com>,
        Jack Chen <jianyan2@...inois.edu>,
        linux-riscv@...ts.infradead.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        linux-s390@...r.kernel.org, YiFei Zhu <yifeifz2@...inois.edu>,
        linux-csky@...r.kernel.org, Tianyin Xu <tyxu@...inois.edu>,
        linux-xtensa@...ux-xtensa.org, Kees Cook <keescook@...omium.org>,
        Jann Horn <jannh@...gle.com>,
        Valentin Rothberg <vrothber@...hat.com>,
        Aleksa Sarai <cyphar@...har.com>,
        Josep Torrellas <torrella@...inois.edu>,
        Will Drewry <wad@...omium.org>, linux-parisc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Dimitrios Skarlatos <dskarlat@...cmu.edu>,
        David Laight <David.Laight@...lab.com>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        linuxppc-dev@...ts.ozlabs.org, Tycho Andersen <tycho@...ho.pizza>
Subject: Re: [PATCH seccomp 3/8] powerpc: Enable seccomp architecture tracking

YiFei Zhu <zhuyifei1999@...il.com> writes:
> From: YiFei Zhu <yifeifz2@...inois.edu>
>
> To enable seccomp constant action bitmaps, we need to have a static
> mapping to the audit architecture and system call table size. Add these
> for powerpc.
>
> Signed-off-by: YiFei Zhu <yifeifz2@...inois.edu>
> ---
>  arch/powerpc/include/asm/seccomp.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/seccomp.h b/arch/powerpc/include/asm/seccomp.h
> index 51209f6071c5..3efcc83e9cc6 100644
> --- a/arch/powerpc/include/asm/seccomp.h
> +++ b/arch/powerpc/include/asm/seccomp.h
> @@ -8,4 +8,25 @@
>  
>  #include <asm-generic/seccomp.h>
>  
> +#ifdef __LITTLE_ENDIAN__

As Kees mentioned this should (must?!) match the configured endian.

But I think it would still be better to use the CONFIG symbol, which is
CONFIG_CPU_LITTLE_ENDIAN.

> +#define __SECCOMP_ARCH_LE_BIT		__AUDIT_ARCH_LE
> +#else
> +#define __SECCOMP_ARCH_LE_BIT		0
> +#endif
> +
> +#ifdef CONFIG_PPC64
> +# define SECCOMP_ARCH_NATIVE		(AUDIT_ARCH_PPC64 | __SECCOMP_ARCH_LE)

You use __SECCOMP_ARCH_LE there, but previously you only defined
__SECCOMP_ARCH_LE_BIT.

Is there some magic somewhere that defines __SECCOMP_ARCH_LE based on
__SECCOMP_ARCH_LE_BIT ?

> +# define SECCOMP_ARCH_NATIVE_NR		NR_syscalls
> +# define SECCOMP_ARCH_NATIVE_NAME	"ppc64"

What's the name used for?

Usually we use "ppc64" for 64-bit big endian and "ppc64le" for 64-bit
little endian.

> +# ifdef CONFIG_COMPAT
> +#  define SECCOMP_ARCH_COMPAT		(AUDIT_ARCH_PPC | __SECCOMP_ARCH_LE)
> +#  define SECCOMP_ARCH_COMPAT_NR	NR_syscalls
> +#  define SECCOMP_ARCH_COMPAT_NAME	"powerpc"

And usually we use "ppc" for 32-bit.

> +# endif
> +#else /* !CONFIG_PPC64 */
> +# define SECCOMP_ARCH_NATIVE		(AUDIT_ARCH_PPC | __SECCOMP_ARCH_LE)
> +# define SECCOMP_ARCH_NATIVE_NR		NR_syscalls
> +# define SECCOMP_ARCH_NATIVE_NAME	"powerpc"
> +#endif
> +
>  #endif	/* _ASM_POWERPC_SECCOMP_H */
> -- 
> 2.29.2


cheers