1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
4 */
5
6#include <linux/kernel.h>
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/netlink.h>
10#include <linux/netfilter.h>
11#include <linux/netfilter/nf_tables.h>
12#include <linux/ip.h>
13#include <linux/ipv6.h>
14#include <net/netfilter/nf_tables.h>
15#include <net/netfilter/nf_tables_offload.h>
16#include <net/netfilter/nf_dup_netdev.h>
17#include <net/neighbour.h>
18#include <net/ip.h>
19
20struct nft_fwd_netdev {
21 u8 sreg_dev;
22};
23
24static void nft_fwd_netdev_eval(const struct nft_expr *expr,
25 struct nft_regs *regs,
26 const struct nft_pktinfo *pkt)
27{
28 struct nft_fwd_netdev *priv = nft_expr_priv(expr);
29 int oif = regs->data[priv->sreg_dev];
30 struct sk_buff *skb = pkt->skb;
31
32 /* This is used by ifb only. */
33 skb->skb_iif = skb->dev->ifindex;
34 skb_set_redirected(skb, from_ingress: nft_hook(pkt) == NF_NETDEV_INGRESS);
35
36 nf_fwd_netdev_egress(pkt, oif);
37 regs->verdict.code = NF_STOLEN;
38}
39
40static const struct nla_policy nft_fwd_netdev_policy[NFTA_FWD_MAX + 1] = {
41 [NFTA_FWD_SREG_DEV] = { .type = NLA_U32 },
42 [NFTA_FWD_SREG_ADDR] = { .type = NLA_U32 },
43 [NFTA_FWD_NFPROTO] = NLA_POLICY_MAX(NLA_BE32, 255),
44};
45
46static int nft_fwd_netdev_init(const struct nft_ctx *ctx,
47 const struct nft_expr *expr,
48 const struct nlattr * const tb[])
49{
50 struct nft_fwd_netdev *priv = nft_expr_priv(expr);
51
52 if (tb[NFTA_FWD_SREG_DEV] == NULL)
53 return -EINVAL;
54
55 return nft_parse_register_load(attr: tb[NFTA_FWD_SREG_DEV], sreg: &priv->sreg_dev,
56 len: sizeof(int));
57}
58
59static int nft_fwd_netdev_dump(struct sk_buff *skb,
60 const struct nft_expr *expr, bool reset)
61{
62 struct nft_fwd_netdev *priv = nft_expr_priv(expr);
63
64 if (nft_dump_register(skb, attr: NFTA_FWD_SREG_DEV, reg: priv->sreg_dev))
65 goto nla_put_failure;
66
67 return 0;
68
69nla_put_failure:
70 return -1;
71}
72
73static int nft_fwd_netdev_offload(struct nft_offload_ctx *ctx,
74 struct nft_flow_rule *flow,
75 const struct nft_expr *expr)
76{
77 const struct nft_fwd_netdev *priv = nft_expr_priv(expr);
78 int oif = ctx->regs[priv->sreg_dev].data.data[0];
79
80 return nft_fwd_dup_netdev_offload(ctx, flow, id: FLOW_ACTION_REDIRECT, oif);
81}
82
83static bool nft_fwd_netdev_offload_action(const struct nft_expr *expr)
84{
85 return true;
86}
87
88struct nft_fwd_neigh {
89 u8 sreg_dev;
90 u8 sreg_addr;
91 u8 nfproto;
92};
93
94static void nft_fwd_neigh_eval(const struct nft_expr *expr,
95 struct nft_regs *regs,
96 const struct nft_pktinfo *pkt)
97{
98 struct nft_fwd_neigh *priv = nft_expr_priv(expr);
99 void *addr = &regs->data[priv->sreg_addr];
100 int oif = regs->data[priv->sreg_dev];
101 unsigned int verdict = NF_STOLEN;
102 struct sk_buff *skb = pkt->skb;
103 struct net_device *dev;
104 int neigh_table;
105
106 switch (priv->nfproto) {
107 case NFPROTO_IPV4: {
108 struct iphdr *iph;
109
110 if (skb->protocol != htons(ETH_P_IP)) {
111 verdict = NFT_BREAK;
112 goto out;
113 }
114 if (skb_try_make_writable(skb, write_len: sizeof(*iph))) {
115 verdict = NF_DROP;
116 goto out;
117 }
118 iph = ip_hdr(skb);
119 ip_decrease_ttl(iph);
120 neigh_table = NEIGH_ARP_TABLE;
121 break;
122 }
123 case NFPROTO_IPV6: {
124 struct ipv6hdr *ip6h;
125
126 if (skb->protocol != htons(ETH_P_IPV6)) {
127 verdict = NFT_BREAK;
128 goto out;
129 }
130 if (skb_try_make_writable(skb, write_len: sizeof(*ip6h))) {
131 verdict = NF_DROP;
132 goto out;
133 }
134 ip6h = ipv6_hdr(skb);
135 ip6h->hop_limit--;
136 neigh_table = NEIGH_ND_TABLE;
137 break;
138 }
139 default:
140 verdict = NFT_BREAK;
141 goto out;
142 }
143
144 dev = dev_get_by_index_rcu(net: nft_net(pkt), ifindex: oif);
145 if (dev == NULL)
146 return;
147
148 skb->dev = dev;
149 skb_clear_tstamp(skb);
150 neigh_xmit(fam: neigh_table, dev, addr, skb);
151out:
152 regs->verdict.code = verdict;
153}
154
155static int nft_fwd_neigh_init(const struct nft_ctx *ctx,
156 const struct nft_expr *expr,
157 const struct nlattr * const tb[])
158{
159 struct nft_fwd_neigh *priv = nft_expr_priv(expr);
160 unsigned int addr_len;
161 int err;
162
163 if (!tb[NFTA_FWD_SREG_DEV] ||
164 !tb[NFTA_FWD_SREG_ADDR] ||
165 !tb[NFTA_FWD_NFPROTO])
166 return -EINVAL;
167
168 priv->nfproto = ntohl(nla_get_be32(tb[NFTA_FWD_NFPROTO]));
169
170 switch (priv->nfproto) {
171 case NFPROTO_IPV4:
172 addr_len = sizeof(struct in_addr);
173 break;
174 case NFPROTO_IPV6:
175 addr_len = sizeof(struct in6_addr);
176 break;
177 default:
178 return -EOPNOTSUPP;
179 }
180
181 err = nft_parse_register_load(attr: tb[NFTA_FWD_SREG_DEV], sreg: &priv->sreg_dev,
182 len: sizeof(int));
183 if (err < 0)
184 return err;
185
186 return nft_parse_register_load(attr: tb[NFTA_FWD_SREG_ADDR], sreg: &priv->sreg_addr,
187 len: addr_len);
188}
189
190static int nft_fwd_neigh_dump(struct sk_buff *skb,
191 const struct nft_expr *expr, bool reset)
192{
193 struct nft_fwd_neigh *priv = nft_expr_priv(expr);
194
195 if (nft_dump_register(skb, attr: NFTA_FWD_SREG_DEV, reg: priv->sreg_dev) ||
196 nft_dump_register(skb, attr: NFTA_FWD_SREG_ADDR, reg: priv->sreg_addr) ||
197 nla_put_be32(skb, attrtype: NFTA_FWD_NFPROTO, htonl(priv->nfproto)))
198 goto nla_put_failure;
199
200 return 0;
201
202nla_put_failure:
203 return -1;
204}
205
206static int nft_fwd_validate(const struct nft_ctx *ctx,
207 const struct nft_expr *expr,
208 const struct nft_data **data)
209{
210 return nft_chain_validate_hooks(chain: ctx->chain, hook_flags: (1 << NF_NETDEV_INGRESS) |
211 (1 << NF_NETDEV_EGRESS));
212}
213
214static struct nft_expr_type nft_fwd_netdev_type;
215static const struct nft_expr_ops nft_fwd_neigh_netdev_ops = {
216 .type = &nft_fwd_netdev_type,
217 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_neigh)),
218 .eval = nft_fwd_neigh_eval,
219 .init = nft_fwd_neigh_init,
220 .dump = nft_fwd_neigh_dump,
221 .validate = nft_fwd_validate,
222 .reduce = NFT_REDUCE_READONLY,
223};
224
225static const struct nft_expr_ops nft_fwd_netdev_ops = {
226 .type = &nft_fwd_netdev_type,
227 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_netdev)),
228 .eval = nft_fwd_netdev_eval,
229 .init = nft_fwd_netdev_init,
230 .dump = nft_fwd_netdev_dump,
231 .validate = nft_fwd_validate,
232 .reduce = NFT_REDUCE_READONLY,
233 .offload = nft_fwd_netdev_offload,
234 .offload_action = nft_fwd_netdev_offload_action,
235};
236
237static const struct nft_expr_ops *
238nft_fwd_select_ops(const struct nft_ctx *ctx,
239 const struct nlattr * const tb[])
240{
241 if (tb[NFTA_FWD_SREG_ADDR])
242 return &nft_fwd_neigh_netdev_ops;
243 if (tb[NFTA_FWD_SREG_DEV])
244 return &nft_fwd_netdev_ops;
245
246 return ERR_PTR(error: -EOPNOTSUPP);
247}
248
249static struct nft_expr_type nft_fwd_netdev_type __read_mostly = {
250 .family = NFPROTO_NETDEV,
251 .name = "fwd",
252 .select_ops = nft_fwd_select_ops,
253 .policy = nft_fwd_netdev_policy,
254 .maxattr = NFTA_FWD_MAX,
255 .owner = THIS_MODULE,
256};
257
258static int __init nft_fwd_netdev_module_init(void)
259{
260 return nft_register_expr(&nft_fwd_netdev_type);
261}
262
263static void __exit nft_fwd_netdev_module_exit(void)
264{
265 nft_unregister_expr(&nft_fwd_netdev_type);
266}
267
268module_init(nft_fwd_netdev_module_init);
269module_exit(nft_fwd_netdev_module_exit);
270
271MODULE_LICENSE("GPL");
272MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
273MODULE_DESCRIPTION("nftables netdev packet forwarding support");
274MODULE_ALIAS_NFT_AF_EXPR(5, "fwd");
275

source code of linux/net/netfilter/nft_fwd_netdev.c