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

From: Andy Lutomirski
Date: Thu Jul 26 2012 - 11:42:10 EST


On Tue, Jul 17, 2012 at 4:19 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> Cc: Will Drewry <wad@xxxxxxxxxxxx>
> ---
> 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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