libbpf: Add link-based API for tcx

Implement tcx BPF link support for libbpf.

The bpf_program__attach_fd() API has been refactored slightly in order to pass
bpf_link_create_opts pointer as input.

A new bpf_program__attach_tcx() has been added on top of this which allows for
passing all relevant data via extensible struct bpf_tcx_opts.

The program sections tcx/ingress and tcx/egress correspond to the hook locations
for tc ingress and egress, respectively.

For concrete usage examples, see the extensive selftests that have been
developed as part of this series.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230719140858.13224-5-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 674e5788eb10..55b97b208754 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -733,6 +733,21 @@ LIBBPF_API struct bpf_link *
 bpf_program__attach_netfilter(const struct bpf_program *prog,
 			      const struct bpf_netfilter_opts *opts);
 
+struct bpf_tcx_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	__u32 flags;
+	__u32 relative_fd;
+	__u32 relative_id;
+	__u64 expected_revision;
+	size_t :0;
+};
+#define bpf_tcx_opts__last_field expected_revision
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,
+			const struct bpf_tcx_opts *opts);
+
 struct bpf_map;
 
 LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);