Re: [PATCH net-next v2 8/9] net: filter: rework/optimize internal BPF interpreter's instruction set

On 03/25/2014 05:17 PM, David Miller wrote:

From: Daniel Borkmann <redacted>
Date: Tue, 25 Mar 2014 13:10:56 +0100

quoted

  - Conditional jt/jf targets replaced with jt/fall-through,
    and forward/backward jumps now possible as well

Ummm... does anyone even remember why backwards jumps were not allowed
in the original BPF?

It's to guarentee forward progress in the filter.

Allowing branching backward would allow endless loops.

Please remove this feature.

If you allow loops, it greatly increases the expressibility of the
language, but we would really need another control to limit CPU usage.

	-hpa