On Wed, Nov 17, 2021 at 4:32 PM Martin Kelly <martin.kelly@xxxxxxxxxxxxxxx> wrote: > > > > > On Tue, Nov 16, 2021 at 2:16 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> > > wrote: > > > > > > On 11/15/21 7:20 PM, Martin Kelly wrote: > > > > Hi, > > > > > > > > I have a question regarding the dual licensing provision of bpftool. I > > > > understand that bpftool can be distributed as either GPL 2.0 or BSD 2- > > clause. > > > > That said, bpftool can also auto-generate BPF code that gets specified inline > > > > in the skeleton header file, and it's possible that the BPF code generated is > > > > GPL. What I'm wondering is what happens if bpftool generates GPL-licensed > > BPF > > > > code inside the skeleton header, so that you get a header like this: > > > > > > > > something.skel.h: > > > > /* this file is BSD 2-clause, by nature of dual licensing */ > > > > > > Fwiw, the generated header contains an SPDX identifier: > > > > > > /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ > > > /* THIS FILE IS AUTOGENERATED! */ > > > > > > > /* THIS FILE IS AUTOGENERATED! */ > > > > > > > > /* standard skeleton definitions */ > > > > > > > > ... > > > > > > > > s->data_sz = XXX; > > > > s->data = (void *)"\ > > > > <eBPF bytecode, produced by GPL 2.0 sources, specified in binary> > > > > "; > > > > > > > > My guess is that, based on the choice to dual-license bpftool, the header is > > > > meant to still be BSD 2-clause, and the s->data inline code's GPL license is > > > > not meant to change the licensing of the header itself, but I wanted to > > > > Yes, definitely that is the intent (but not a lawyer either). > > Thanks everyone, that's what I assumed as well. Any objection to a patch clarifying this more explicitly? > > One other, related question: vmlinux.h (generated by "bpftool btf dump file /sys/kernel/btf/vmlinux format c"), does not currently contain a license declaration. I assume this would have to be a GPL header, since vmlinux.h references many GPL'd Linux kernel structs and similar, though again I'm not a lawyer and therefore am not certain. Would you all agree with this? If so, any objection to a patch adding an SPDX line to the generated vmlinux.h? Is vmlinux DWARF data GPL'ed? I certainly hope not. So vmlinux.h shouldn't be licensed under GPL.
