[PATCH bpf-next 5/8] libbpf: wire up token_fd into feature probing logic

[John Fastabend]

Andrii Nakryiko wrote:
> Adjust feature probing callbacks to take into account optional token_fd.
> In unprivileged contexts, some feature detectors would fail to detect
> kernel support just because BPF program, BPF map, or BTF object can't be
> loaded due to privileged nature of those operations. So when BPF object
> is loaded with BPF token, this token should be used for feature probing.
> 
> This patch is setting support for this scenario, but we don't yet pass
> non-zero token FD. This will be added in the next patch.
> 
> We also switched BPF cookie detector from using kprobe program to
> tracepoint one, as tracepoint is somewhat less dangerous BPF program
> type and has higher likelihood of being allowed through BPF token in the
> future. This change has no effect on detection behavior.
> 
> Signed-off-by: Andrii Nakryiko <andrii at kernel.org>
> ---

Acked-by: John Fastabend <john.fastabend at gmail.com>