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// 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 {
__be16 sport;
__be16 dport;
};
enum bpf_fou_encap_type {
FOU_BPF_ENCAP_FOU,
FOU_BPF_ENCAP_GUE,
};
__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)
{
struct sk_buff *skb = (struct sk_buff *)skb_ctx;
struct ip_tunnel_info *info = skb_tunnel_info(skb);
if (unlikely(!encap))
return -EINVAL;
if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX)))
return -EINVAL;
switch (type) {
case FOU_BPF_ENCAP_FOU:
info->encap.type = TUNNEL_ENCAP_FOU;
break;
case FOU_BPF_ENCAP_GUE:
info->encap.type = TUNNEL_ENCAP_GUE;
break;
default:
info->encap.type = TUNNEL_ENCAP_NONE;
}
if (info->key.tun_flags & TUNNEL_CSUM)
info->encap.flags |= TUNNEL_ENCAP_FLAG_CSUM;
info->encap.sport = encap->sport;
info->encap.dport = encap->dport;
return 0;
}
/* 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)
{
struct sk_buff *skb = (struct sk_buff *)skb_ctx;
struct ip_tunnel_info *info = skb_tunnel_info(skb);
if (unlikely(!info))
return -EINVAL;
encap->sport = info->encap.sport;
encap->dport = info->encap.dport;
return 0;
}
__bpf_kfunc_end_defs();
BTF_SET8_START(fou_kfunc_set)
BTF_ID_FLAGS(func, bpf_skb_set_fou_encap)
BTF_ID_FLAGS(func, bpf_skb_get_fou_encap)
BTF_SET8_END(fou_kfunc_set)
static const struct btf_kfunc_id_set fou_bpf_kfunc_set = {
.owner = THIS_MODULE,
.set = &fou_kfunc_set,
};
int register_fou_bpf(void)
{
return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
&fou_bpf_kfunc_set);
}
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