1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Unstable NAT Helpers for XDP and TC-BPF hook
3  *
4  * These are called from the XDP and 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 #include <net/netfilter/nf_conntrack_bpf.h>
12 #include <net/netfilter/nf_conntrack_core.h>
13 #include <net/netfilter/nf_nat.h>
14 
15 __bpf_kfunc_start_defs();
16 
17 /* bpf_ct_set_nat_info - Set source or destination nat address
18  *
19  * Set source or destination nat address of the newly allocated
20  * nf_conn before insertion. This must be invoked for referenced
21  * PTR_TO_BTF_ID to nf_conn___init.
22  *
23  * Parameters:
24  * @nfct	- Pointer to referenced nf_conn object, obtained using
25  *		  bpf_xdp_ct_alloc or bpf_skb_ct_alloc.
26  * @addr	- Nat source/destination address
27  * @port	- Nat source/destination port. Non-positive values are
28  *		  interpreted as select a random port.
29  * @manip	- NF_NAT_MANIP_SRC or NF_NAT_MANIP_DST
30  */
bpf_ct_set_nat_info(struct nf_conn___init * nfct,union nf_inet_addr * addr,int port,enum nf_nat_manip_type manip)31 __bpf_kfunc int bpf_ct_set_nat_info(struct nf_conn___init *nfct,
32 				    union nf_inet_addr *addr, int port,
33 				    enum nf_nat_manip_type manip)
34 {
35 	struct nf_conn *ct = (struct nf_conn *)nfct;
36 	u16 proto = nf_ct_l3num(ct);
37 	struct nf_nat_range2 range;
38 
39 	if (proto != NFPROTO_IPV4 && proto != NFPROTO_IPV6)
40 		return -EINVAL;
41 
42 	memset(&range, 0, sizeof(struct nf_nat_range2));
43 	range.flags = NF_NAT_RANGE_MAP_IPS;
44 	range.min_addr = *addr;
45 	range.max_addr = range.min_addr;
46 	if (port > 0) {
47 		range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
48 		range.min_proto.all = cpu_to_be16(port);
49 		range.max_proto.all = range.min_proto.all;
50 	}
51 
52 	return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
53 }
54 
55 __bpf_kfunc_end_defs();
56 
57 BTF_KFUNCS_START(nf_nat_kfunc_set)
58 BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_TRUSTED_ARGS)
59 BTF_KFUNCS_END(nf_nat_kfunc_set)
60 
61 static const struct btf_kfunc_id_set nf_bpf_nat_kfunc_set = {
62 	.owner = THIS_MODULE,
63 	.set   = &nf_nat_kfunc_set,
64 };
65 
register_nf_nat_bpf(void)66 int register_nf_nat_bpf(void)
67 {
68 	int ret;
69 
70 	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP,
71 					&nf_bpf_nat_kfunc_set);
72 	if (ret)
73 		return ret;
74 
75 	return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
76 					 &nf_bpf_nat_kfunc_set);
77 }
78