netdev - Re: [bpf-next v2 8/9] bpf: Provide helper to do forwarding lookups in kernel FIB table

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Date:   Mon, 7 May 2018 16:10:03 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jesper Dangaard Brouer <brouer@...hat.com>,
        David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org, borkmann@...earbox.net, ast@...nel.org,
        davem@...emloft.net, shm@...ulusnetworks.com,
        roopa@...ulusnetworks.com, toke@...e.dk, john.fastabend@...il.com
Subject: Re: [bpf-next v2 8/9] bpf: Provide helper to do forwarding lookups in
 kernel FIB table

On 05/07/2018 03:35 PM, Jesper Dangaard Brouer wrote:
> On Thu,  3 May 2018 19:54:31 -0700 David Ahern <dsahern@...il.com> wrote:
> 
>> diff --git a/net/core/filter.c b/net/core/filter.c
>> index 6877426c23a6..cf0d27acf1d1 100644
>> --- a/net/core/filter.c
>> +++ b/net/core/filter.c
> [...]
>> +static const struct bpf_func_proto bpf_xdp_fib_lookup_proto = {
>> +	.func		= bpf_xdp_fib_lookup,
>> +	.gpl_only	= true,
> 
> Is it a deliberate choice to require BPF-progs using this helper to be
> GPL licensed?
> 
> Asking as this seems to be the first network related helper with this
> requirement, while this is typical for tracing related helpers.

Good point, we should remove that. In networking it's only the perf event
output helpers tying into tracing bits. After all, if you do a route lookup
via netlink from user space there's no such restriction at all.