Messages in this thread | | | From | Andy Lutomirski <> | Date | Sat, 28 Jun 2014 08:35:51 -0700 | Subject | Re: [PATCH RFC net-next 07/14] bpf: expand BPF syscall with program load/unload |
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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. Something like "look up the uid that opened a port," on the other hand, maybe should be.
--Andy
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