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Message-ID: <20140628152104.GB29548@kroah.com>
Date: Sat, 28 Jun 2014 11:21:04 -0400
From: Greg KH <gregkh@...uxfoundation.org>
To: Alexei Starovoitov <ast@...mgrid.com>
Cc: Andy Lutomirski <luto@...capital.net>,
"David S. Miller" <davem@...emloft.net>,
Ingo Molnar <mingo@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Steven Rostedt <rostedt@...dmis.org>,
Daniel Borkmann <dborkman@...hat.com>,
Chema Gonzalez <chema@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Jiri Olsa <jolsa@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
Linux API <linux-api@...r.kernel.org>,
Network Development <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC net-next 07/14] bpf: expand BPF syscall with program
load/unload
On Sat, Jun 28, 2014 at 12:26:14AM -0700, Alexei Starovoitov wrote:
> On Fri, Jun 27, 2014 at 11:28 PM, Andy Lutomirski <luto@...capital.net> wrote:
> > On Fri, Jun 27, 2014 at 11:12 PM, Alexei Starovoitov <ast@...mgrid.com> wrote:
> > If you want to add GPL-only functions in the future, that would be one
> > thing. But if someone writes a nice eBPF compiler, and someone else
> > writes a little program that filters on network packets, I see no
> > reason to claim that the little program is a derivative work of the
> > kernel and therefore must be GPL.
>
> I think we have to draw a line somewhere. Say, tomorrow I want
> to modify libpcap to emit eBPF based on existing tcpdump syntax.
> Would it mean that tcpdump filter strings are GPLed? Definitely not,
> since they existed before and can function without new libpcap.
> But if I write a new packet filtering program in C, compile it
> using LLVM->eBPF and call into in-kernel helper functions
> (like bpf_map_lookup_elem()), I think it's exactly the derivative work.
> It's analogous to kernel modules. If module wants to call
> export_symbol_gpl() functions, it needs to be GPLed. Here all helper
> functions are GPL. So we just have a blank check for eBPF program.
I agree, these eBFP programs should be GPL-compatible licensed as well.
greg k-h
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