1// SPDX-License-Identifier: GPL-2.0-only
2/* Unstable XFRM Helpers for TC-BPF hook
3 *
4 * These are called from SCHED_CLS BPF programs. Note that it is
5 * allowed to break compatibility for these functions since the interface they
6 * are exposed through to BPF programs is explicitly unstable.
7 */
8
9#include <linux/bpf.h>
10#include <linux/btf_ids.h>
11
12#include <net/dst_metadata.h>
13#include <net/xfrm.h>
14
15/* bpf_xfrm_info - XFRM metadata information
16 *
17 * Members:
18 * @if_id	- XFRM if_id:
19 *		    Transmit: if_id to be used in policy and state lookups
20 *		    Receive: if_id of the state matched for the incoming packet
21 * @link	- Underlying device ifindex:
22 *		    Transmit: used as the underlying device in VRF routing
23 *		    Receive: the device on which the packet had been received
24 */
25struct bpf_xfrm_info {
26	u32 if_id;
27	int link;
28};
29
30__diag_push();
31__diag_ignore_all("-Wmissing-prototypes",
32		  "Global functions as their definitions will be in xfrm_interface BTF");
33
34/* bpf_skb_get_xfrm_info - Get XFRM metadata
35 *
36 * Parameters:
37 * @skb_ctx	- Pointer to ctx (__sk_buff) in TC program
38 *		    Cannot be NULL
39 * @to		- Pointer to memory to which the metadata will be copied
40 *		    Cannot be NULL
41 */
42__bpf_kfunc int bpf_skb_get_xfrm_info(struct __sk_buff *skb_ctx, struct bpf_xfrm_info *to)
43{
44	struct sk_buff *skb = (struct sk_buff *)skb_ctx;
45	struct xfrm_md_info *info;
46
47	info = skb_xfrm_md_info(skb);
48	if (!info)
49		return -EINVAL;
50
51	to->if_id = info->if_id;
52	to->link = info->link;
53	return 0;
54}
55
56/* bpf_skb_get_xfrm_info - Set XFRM metadata
57 *
58 * Parameters:
59 * @skb_ctx	- Pointer to ctx (__sk_buff) in TC program
60 *		    Cannot be NULL
61 * @from	- Pointer to memory from which the metadata will be copied
62 *		    Cannot be NULL
63 */
64__bpf_kfunc int bpf_skb_set_xfrm_info(struct __sk_buff *skb_ctx, const struct bpf_xfrm_info *from)
65{
66	struct sk_buff *skb = (struct sk_buff *)skb_ctx;
67	struct metadata_dst *md_dst;
68	struct xfrm_md_info *info;
69
70	if (unlikely(skb_metadata_dst(skb)))
71		return -EINVAL;
72
73	if (!xfrm_bpf_md_dst) {
74		struct metadata_dst __percpu *tmp;
75
76		tmp = metadata_dst_alloc_percpu(0, METADATA_XFRM, GFP_ATOMIC);
77		if (!tmp)
78			return -ENOMEM;
79		if (cmpxchg(&xfrm_bpf_md_dst, NULL, tmp))
80			metadata_dst_free_percpu(tmp);
81	}
82	md_dst = this_cpu_ptr(xfrm_bpf_md_dst);
83
84	info = &md_dst->u.xfrm_info;
85
86	info->if_id = from->if_id;
87	info->link = from->link;
88	skb_dst_force(skb);
89	info->dst_orig = skb_dst(skb);
90
91	dst_hold((struct dst_entry *)md_dst);
92	skb_dst_set(skb, (struct dst_entry *)md_dst);
93	return 0;
94}
95
96__diag_pop()
97
98BTF_SET8_START(xfrm_ifc_kfunc_set)
99BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info)
100BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info)
101BTF_SET8_END(xfrm_ifc_kfunc_set)
102
103static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {
104	.owner = THIS_MODULE,
105	.set   = &xfrm_ifc_kfunc_set,
106};
107
108int __init register_xfrm_interface_bpf(void)
109{
110	return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
111					 &xfrm_interface_kfunc_set);
112}
113