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