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 */
25 struct bpf_xfrm_info {
26 u32 if_id;
27 int link;
28 };
29
30 __bpf_kfunc_start_defs();
31
32 /* bpf_skb_get_xfrm_info - Get XFRM metadata
33 *
34 * Parameters:
35 * @skb_ctx - Pointer to ctx (__sk_buff) in TC program
36 * Cannot be NULL
37 * @to - Pointer to memory to which the metadata will be copied
38 * Cannot be NULL
39 */
40 __bpf_kfunc int bpf_skb_get_xfrm_info(struct __sk_buff *skb_ctx, struct bpf_xfrm_info *to)
41 {
42 struct sk_buff *skb = (struct sk_buff *)skb_ctx;
43 struct xfrm_md_info *info;
44
45 info = skb_xfrm_md_info(skb);
46 if (!info)
47 return -EINVAL;
48
49 to->if_id = info->if_id;
50 to->link = info->link;
51 return 0;
52 }
53
54 /* bpf_skb_get_xfrm_info - Set XFRM metadata
55 *
56 * Parameters:
57 * @skb_ctx - Pointer to ctx (__sk_buff) in TC program
58 * Cannot be NULL
59 * @from - Pointer to memory from which the metadata will be copied
60 * Cannot be NULL
61 */
62 __bpf_kfunc int bpf_skb_set_xfrm_info(struct __sk_buff *skb_ctx, const struct bpf_xfrm_info *from)
63 {
64 struct sk_buff *skb = (struct sk_buff *)skb_ctx;
65 struct metadata_dst *md_dst;
66 struct xfrm_md_info *info;
67
68 if (unlikely(skb_metadata_dst(skb)))
69 return -EINVAL;
70
71 if (!xfrm_bpf_md_dst) {
72 struct metadata_dst __percpu *tmp;
73
74 tmp = metadata_dst_alloc_percpu(0, METADATA_XFRM, GFP_ATOMIC);
75 if (!tmp)
76 return -ENOMEM;
77 if (cmpxchg(&xfrm_bpf_md_dst, NULL, tmp))
78 metadata_dst_free_percpu(tmp);
79 }
80 md_dst = this_cpu_ptr(xfrm_bpf_md_dst);
81
82 info = &md_dst->u.xfrm_info;
83
84 info->if_id = from->if_id;
85 info->link = from->link;
86 skb_dst_force(skb);
87 info->dst_orig = skb_dst(skb);
88
89 dst_hold((struct dst_entry *)md_dst);
90 skb_dst_set(skb, (struct dst_entry *)md_dst);
91 return 0;
92 }
93
94 __bpf_kfunc_end_defs();
95
96 BTF_KFUNCS_START(xfrm_ifc_kfunc_set)
97 BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info)
98 BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info)
99 BTF_KFUNCS_END(xfrm_ifc_kfunc_set)
100
101 static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {
102 .owner = THIS_MODULE,
103 .set = &xfrm_ifc_kfunc_set,
104 };
105
106 int __init register_xfrm_interface_bpf(void)
107 {
108 return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
109 &xfrm_interface_kfunc_set);
110 }
111
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