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 __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 */
bpf_skb_get_xfrm_info(struct __sk_buff * skb_ctx,struct bpf_xfrm_info * to)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 */
bpf_skb_set_xfrm_info(struct __sk_buff * skb_ctx,const struct bpf_xfrm_info * from)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
98 BTF_SET8_START(xfrm_ifc_kfunc_set)
99 BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info)
100 BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info)
101 BTF_SET8_END(xfrm_ifc_kfunc_set)
102
103 static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {
104 .owner = THIS_MODULE,
105 .set = &xfrm_ifc_kfunc_set,
106 };
107
register_xfrm_interface_bpf(void)108 int __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