linux/net/ipv4/fou_bpf.c

// SPDX-License-Identifier: GPL-2.0-only
/* Unstable Fou Helpers for TC-BPF hook
 *
 * These are called from SCHED_CLS BPF programs. Note that it is
 * allowed to break compatibility for these functions since the interface they
 * are exposed through to BPF programs is explicitly unstable.
 */

#include <linux/bpf.h>
#include <linux/btf_ids.h>

#include <net/dst_metadata.h>
#include <net/fou.h>

struct bpf_fou_encap { … };

enum bpf_fou_encap_type { … };

__bpf_kfunc_start_defs();

/* bpf_skb_set_fou_encap - Set FOU encap parameters
 *
 * This function allows for using GUE or FOU encapsulation together with an
 * ipip device in collect-metadata mode.
 *
 * It is meant to be used in BPF tc-hooks and after a call to the
 * bpf_skb_set_tunnel_key helper, responsible for setting IP addresses.
 *
 * Parameters:
 * @skb_ctx	Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
 * @encap	Pointer to a `struct bpf_fou_encap` storing UDP src and
 * 		dst ports. If sport is set to 0 the kernel will auto-assign a
 * 		port. This is similar to using `encap-sport auto`.
 * 		Cannot be NULL
 * @type	Encapsulation type for the packet. Their definitions are
 * 		specified in `enum bpf_fou_encap_type`
 */
__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,
				      struct bpf_fou_encap *encap, int type)
{ … }

/* bpf_skb_get_fou_encap - Get FOU encap parameters
 *
 * This function allows for reading encap metadata from a packet received
 * on an ipip device in collect-metadata mode.
 *
 * Parameters:
 * @skb_ctx	Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
 * @encap	Pointer to a struct bpf_fou_encap storing UDP source and
 * 		destination port. Cannot be NULL
 */
__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
				      struct bpf_fou_encap *encap)
{ … }

__bpf_kfunc_end_defs();

BTF_KFUNCS_START(fou_kfunc_set)
BTF_ID_FLAGS(…)
BTF_ID_FLAGS(…)
BTF_KFUNCS_END(…)

static const struct btf_kfunc_id_set fou_bpf_kfunc_set = …;

int register_fou_bpf(void)
{ … }