Re: [PATCH v5 2/3] asm-generic: Add generic seccomp.h for secure computing mode 1

[AKASHI Takahiro]

On 07/24/2014 11:57 PM, Andy Lutomirski wrote:
> On Jul 23, 2014 10:17 PM, "AKASHI Takahiro" <takahiro.akashi@xxxxxxxxxx> wrote:
> > On 07/24/2014 01:41 PM, Kees Cook wrote:
> > > On Wed, Jul 23, 2014 at 8:40 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> 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@xxxxxxxx>
> > > > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> > > > > ---
> > > > >     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@xxxxxxxxxx>
> > > > > + *
> > > > > + * 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.
> >
> >
> > Yeah, that is why I put this file under include/asm-generic.
>
> It seems odd that the header would be added without any users.  I
> guess it's okay, since arm64 uses it in the followup patch.
>
> > > However, I think that should be a separate patch.
> >
> >
> > Do you mean that the code for all the existing archs should also be changed
> > to use this (common) header?
>
> If that works, yes.

As is often the case, the patch itself is quite simple, but I can't
test it on other architectures.

-Takahiro AKASHI

> --Andy
>
> > -Takahiro AKASHI
> > > -Kees
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