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