Re: [PATCH RFC net-next 07/14] bpf: expand BPF syscall with program load/unload
[Posted July 1, 2014 by corbet]
| From: |
| Alexei Starovoitov <ast-AT-plumgrid.com> |
| To: |
| Andy Lutomirski <luto-AT-amacapital.net>, David Laight <David.Laight-AT-aculab.com> |
| Subject: |
| Re: [PATCH RFC net-next 07/14] bpf: expand BPF syscall with program load/unload |
| Date: |
| Mon, 30 Jun 2014 13:39:31 -0700 |
| Message-ID: |
| <CAMEtUuxSdw+9WiB2ps0aYE5hdH9NTnq48VdELLEg17tz1B96WQ@mail.gmail.com> |
| Cc: |
| Greg KH <gregkh-AT-linuxfoundation.org>, "David S. Miller" <davem-AT-davemloft.net>, Ingo Molnar <mingo-AT-kernel.org>, Linus Torvalds <torvalds-AT-linux-foundation.org>, Steven Rostedt <rostedt-AT-goodmis.org>, Daniel Borkmann <dborkman-AT-redhat.com>, Chema Gonzalez <chema-AT-google.com>, Eric Dumazet <edumazet-AT-google.com>, Peter Zijlstra <a.p.zijlstra-AT-chello.nl>, Arnaldo Carvalho de Melo <acme-AT-infradead.org>, Jiri Olsa <jolsa-AT-redhat.com>, Thomas Gleixner <tglx-AT-linutronix.de>, "H. Peter Anvin" <hpa-AT-zytor.com>, Andrew Morton <akpm-AT-linux-foundation.org>, Kees Cook <keescook-AT-chromium.org>, Linux API <linux-api-AT-vger.kernel.org>, Network Development <netdev-AT-vger.kernel.org>, "linux-kernel-AT-vger.kernel.org" <linux-kernel-AT-vger.kernel.org> |
| Archive‑link: | |
Article |
On Sat, Jun 28, 2014 at 8:35 AM, Andy Lutomirski <luto@amacapital.net> wrote:
> On Sat, Jun 28, 2014 at 8:21 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> 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@amacapital.net> wrote:
>>> > On Fri, Jun 27, 2014 at 11:12 PM, Alexei Starovoitov <ast@plumgrid.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.
>
> I think I'd be happy with an export_symbol_gpl analogue. I might
> argue that bpf_map_lookup_elem shouldn't be gpl-only, though.
ok. sounds like module-like approach will be more acceptable to potential
user base. Will change it. Last thing I want to do is to scary users away.
