linux-kernel - Re: [PATCH 3.5 2/2] seccomp: Future-proof against silly tracers

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Message-ID: <CALCETrUJiXoc8Jq-fdTsx4oq9j8e-NHSiYOJdy37o6uy2cJZuA@mail.gmail.com>
Date:	Thu, 26 Jul 2012 08:41:56 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Cc:	Will Drewry <wad@...omium.org>, Kees Cook <keescook@...omium.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [PATCH 3.5 2/2] seccomp: Future-proof against silly tracers

On Tue, Jul 17, 2012 at 4:19 PM, Andy Lutomirski <luto@...capital.net> wrote:
> Currently, if a tracer changes a syscall nr to __NR_future_enosys,
> behavior will differ between kernels that know about
> __NR_future_enosys (and return -ENOSYS) and older kernels (which
> return the value from pt_regs).  This is silly; we should just
> return -ENOSYS.
>
> This is unlikely to ever happen on x86 because the return value in
> pt_regs starts out as -ENOSYS, but a silly tracer can change that.
>
> Signed-off-by: Andy Lutomirski <luto@...capital.net>
> Cc: Will Drewry <wad@...omium.org>
> ---
>  arch/x86/include/asm/syscall.h |   11 +++++++++++
>  kernel/seccomp.c               |   15 +++++++++++++++
>  2 files changed, 26 insertions(+), 0 deletions(-)

Will, can you pick this, or some version of it, up in your
seccomp-for-ARM tree or wherever your development is?

--Andy
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