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    SubjectRe: [PATCH v5 2/3] asm-generic: Add generic seccomp.h for secure computing mode 1
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    On Wed, Jul 23, 2014 at 8:40 PM, Andy Lutomirski <luto@amacapital.net> wrote:
    > On 07/22/2014 02:14 AM, AKASHI Takahiro wrote:
    >>
    >> Those values (__NR_seccomp_*) are used solely in secure_computing()
    >> to identify mode 1 system calls. If compat system calls have different
    >> syscall numbers, asm/seccomp.h may override them.
    >>
    >> Acked-by: Arnd Bergmann <arnd@arndb.de>
    >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
    >> ---
    >> include/asm-generic/seccomp.h | 28 ++++++++++++++++++++++++++++
    >> 1 file changed, 28 insertions(+)
    >> create mode 100644 include/asm-generic/seccomp.h
    >>
    >> diff --git a/include/asm-generic/seccomp.h b/include/asm-generic/seccomp.h
    >> new file mode 100644
    >> index 0000000..5e97022
    >> --- /dev/null
    >> +++ b/include/asm-generic/seccomp.h
    >> @@ -0,0 +1,28 @@
    >> +/*
    >> + * include/asm-generic/seccomp.h
    >> + *
    >> + * Copyright (C) 2014 Linaro Limited
    >> + * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
    >> + *
    >> + * This program is free software; you can redistribute it and/or modify
    >> + * it under the terms of the GNU General Public License version 2 as
    >> + * published by the Free Software Foundation.
    >> + */
    >> +#ifndef _ASM_GENERIC_SECCOMP_H
    >> +#define _ASM_GENERIC_SECCOMP_H
    >> +
    >> +#include <asm-generic/unistd.h>
    >> +
    >> +#if defined(CONFIG_COMPAT) && !defined(__NR_seccomp_read_32)
    >> +#define __NR_seccomp_read_32 __NR_read
    >> +#define __NR_seccomp_write_32 __NR_write
    >> +#define __NR_seccomp_exit_32 __NR_exit
    >> +#define __NR_seccomp_sigreturn_32 __NR_rt_sigreturn
    >> +#endif /* CONFIG_COMPAT && ! already defined */
    >> +
    >> +#define __NR_seccomp_read __NR_read
    >> +#define __NR_seccomp_write __NR_write
    >> +#define __NR_seccomp_exit __NR_exit
    >> +#define __NR_seccomp_sigreturn __NR_rt_sigreturn
    >
    >
    > I don't like these names. __NR_seccomp_read sounds like the number of a
    > syscall called seccomp_read.
    >
    > Also, shouldn't something be including this header? I'm confused.

    Ah! Good catch. These names are correct (see kernel/seccomp.c's
    mode1_syscalls and mode1_syscalls_32 arrays), but the location of this
    change was unexpected. I was expecting this file to live in
    arch/*/include/asm/seccomp.h, not in include/asm-generic/seccomp.h.

    However, since it's always the same list, it might make sense to
    consolidate them into a single place as a default to make arch porting
    easier. However, I think that should be a separate patch.

    -Kees

    --
    Kees Cook
    Chrome OS Security


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