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