1// SPDX-License-Identifier: GPL-2.0-only
2
3#include <linux/kernel.h>
4#include <linux/init.h>
5#include <linux/module.h>
6#include <linux/netlink.h>
7#include <linux/netfilter.h>
8#include <linux/netfilter/nf_tables.h>
9#include <linux/netfilter_ipv6.h>
10#include <net/netfilter/nf_tables_core.h>
11#include <net/netfilter/nf_tables.h>
12#include <net/netfilter/nft_fib.h>
13
14#include <net/ip6_fib.h>
15#include <net/ip6_route.h>
16
17static int get_ifindex(const struct net_device *dev)
18{
19	return dev ? dev->ifindex : 0;
20}
21
22static int nft_fib6_flowi_init(struct flowi6 *fl6, const struct nft_fib *priv,
23			       const struct nft_pktinfo *pkt,
24			       const struct net_device *dev,
25			       struct ipv6hdr *iph)
26{
27	int lookup_flags = 0;
28
29	if (priv->flags & NFTA_FIB_F_DADDR) {
30		fl6->daddr = iph->daddr;
31		fl6->saddr = iph->saddr;
32	} else {
33		if (nft_hook(pkt) == NF_INET_FORWARD &&
34		    priv->flags & NFTA_FIB_F_IIF)
35			fl6->flowi6_iif = nft_out(pkt)->ifindex;
36
37		fl6->daddr = iph->saddr;
38		fl6->saddr = iph->daddr;
39	}
40
41	if (ipv6_addr_type(&fl6->daddr) & IPV6_ADDR_LINKLOCAL) {
42		lookup_flags |= RT6_LOOKUP_F_IFACE;
43		fl6->flowi6_oif = get_ifindex(dev ? dev : pkt->skb->dev);
44	} else if (priv->flags & NFTA_FIB_F_IIF) {
45		fl6->flowi6_l3mdev = l3mdev_master_ifindex_rcu(dev);
46	}
47
48	if (ipv6_addr_type(&fl6->saddr) & IPV6_ADDR_UNICAST)
49		lookup_flags |= RT6_LOOKUP_F_HAS_SADDR;
50
51	if (priv->flags & NFTA_FIB_F_MARK)
52		fl6->flowi6_mark = pkt->skb->mark;
53
54	fl6->flowlabel = (*(__be32 *)iph) & IPV6_FLOWINFO_MASK;
55
56	return lookup_flags;
57}
58
59static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
60				const struct nft_pktinfo *pkt,
61				struct ipv6hdr *iph)
62{
63	const struct net_device *dev = NULL;
64	int route_err, addrtype;
65	struct rt6_info *rt;
66	struct flowi6 fl6 = {
67		.flowi6_iif = LOOPBACK_IFINDEX,
68		.flowi6_proto = pkt->tprot,
69		.flowi6_uid = sock_net_uid(nft_net(pkt), NULL),
70	};
71	u32 ret = 0;
72
73	if (priv->flags & NFTA_FIB_F_IIF)
74		dev = nft_in(pkt);
75	else if (priv->flags & NFTA_FIB_F_OIF)
76		dev = nft_out(pkt);
77
78	nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
79
80	if (dev && nf_ipv6_chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
81		ret = RTN_LOCAL;
82
83	route_err = nf_ip6_route(nft_net(pkt), (struct dst_entry **)&rt,
84				 flowi6_to_flowi(&fl6), false);
85	if (route_err)
86		goto err;
87
88	if (rt->rt6i_flags & RTF_REJECT) {
89		route_err = rt->dst.error;
90		dst_release(&rt->dst);
91		goto err;
92	}
93
94	if (ipv6_anycast_destination((struct dst_entry *)rt, &fl6.daddr))
95		ret = RTN_ANYCAST;
96	else if (!dev && rt->rt6i_flags & RTF_LOCAL)
97		ret = RTN_LOCAL;
98
99	dst_release(&rt->dst);
100
101	if (ret)
102		return ret;
103
104	addrtype = ipv6_addr_type(&fl6.daddr);
105
106	if (addrtype & IPV6_ADDR_MULTICAST)
107		return RTN_MULTICAST;
108	if (addrtype & IPV6_ADDR_UNICAST)
109		return RTN_UNICAST;
110
111	return RTN_UNSPEC;
112 err:
113	switch (route_err) {
114	case -EINVAL:
115		return RTN_BLACKHOLE;
116	case -EACCES:
117		return RTN_PROHIBIT;
118	case -EAGAIN:
119		return RTN_THROW;
120	default:
121		break;
122	}
123
124	return RTN_UNREACHABLE;
125}
126
127void nft_fib6_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
128			const struct nft_pktinfo *pkt)
129{
130	const struct nft_fib *priv = nft_expr_priv(expr);
131	int noff = skb_network_offset(pkt->skb);
132	u32 *dest = &regs->data[priv->dreg];
133	struct ipv6hdr *iph, _iph;
134
135	iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
136	if (!iph) {
137		regs->verdict.code = NFT_BREAK;
138		return;
139	}
140
141	*dest = __nft_fib6_eval_type(priv, pkt, iph);
142}
143EXPORT_SYMBOL_GPL(nft_fib6_eval_type);
144
145static bool nft_fib_v6_skip_icmpv6(const struct sk_buff *skb, u8 next, const struct ipv6hdr *iph)
146{
147	if (likely(next != IPPROTO_ICMPV6))
148		return false;
149
150	if (ipv6_addr_type(&iph->saddr) != IPV6_ADDR_ANY)
151		return false;
152
153	return ipv6_addr_type(&iph->daddr) & IPV6_ADDR_LINKLOCAL;
154}
155
156void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
157		   const struct nft_pktinfo *pkt)
158{
159	const struct nft_fib *priv = nft_expr_priv(expr);
160	int noff = skb_network_offset(pkt->skb);
161	const struct net_device *oif = NULL;
162	u32 *dest = &regs->data[priv->dreg];
163	struct ipv6hdr *iph, _iph;
164	struct flowi6 fl6 = {
165		.flowi6_iif = LOOPBACK_IFINDEX,
166		.flowi6_proto = pkt->tprot,
167		.flowi6_uid = sock_net_uid(nft_net(pkt), NULL),
168	};
169	struct rt6_info *rt;
170	int lookup_flags;
171
172	if (priv->flags & NFTA_FIB_F_IIF)
173		oif = nft_in(pkt);
174	else if (priv->flags & NFTA_FIB_F_OIF)
175		oif = nft_out(pkt);
176
177	iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
178	if (!iph) {
179		regs->verdict.code = NFT_BREAK;
180		return;
181	}
182
183	lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif, iph);
184
185	if (nft_hook(pkt) == NF_INET_PRE_ROUTING ||
186	    nft_hook(pkt) == NF_INET_INGRESS) {
187		if (nft_fib_is_loopback(pkt->skb, nft_in(pkt)) ||
188		    nft_fib_v6_skip_icmpv6(pkt->skb, pkt->tprot, iph)) {
189			nft_fib_store_result(dest, priv, nft_in(pkt));
190			return;
191		}
192	}
193
194	*dest = 0;
195	rt = (void *)ip6_route_lookup(nft_net(pkt), &fl6, pkt->skb,
196				      lookup_flags);
197	if (rt->dst.error)
198		goto put_rt_err;
199
200	/* Should not see RTF_LOCAL here */
201	if (rt->rt6i_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL))
202		goto put_rt_err;
203
204	if (oif && oif != rt->rt6i_idev->dev &&
205	    l3mdev_master_ifindex_rcu(rt->rt6i_idev->dev) != oif->ifindex)
206		goto put_rt_err;
207
208	nft_fib_store_result(dest, priv, rt->rt6i_idev->dev);
209 put_rt_err:
210	ip6_rt_put(rt);
211}
212EXPORT_SYMBOL_GPL(nft_fib6_eval);
213
214static struct nft_expr_type nft_fib6_type;
215
216static const struct nft_expr_ops nft_fib6_type_ops = {
217	.type		= &nft_fib6_type,
218	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
219	.eval		= nft_fib6_eval_type,
220	.init		= nft_fib_init,
221	.dump		= nft_fib_dump,
222	.validate	= nft_fib_validate,
223	.reduce		= nft_fib_reduce,
224};
225
226static const struct nft_expr_ops nft_fib6_ops = {
227	.type		= &nft_fib6_type,
228	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
229	.eval		= nft_fib6_eval,
230	.init		= nft_fib_init,
231	.dump		= nft_fib_dump,
232	.validate	= nft_fib_validate,
233	.reduce		= nft_fib_reduce,
234};
235
236static const struct nft_expr_ops *
237nft_fib6_select_ops(const struct nft_ctx *ctx,
238		    const struct nlattr * const tb[])
239{
240	enum nft_fib_result result;
241
242	if (!tb[NFTA_FIB_RESULT])
243		return ERR_PTR(-EINVAL);
244
245	result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
246
247	switch (result) {
248	case NFT_FIB_RESULT_OIF:
249		return &nft_fib6_ops;
250	case NFT_FIB_RESULT_OIFNAME:
251		return &nft_fib6_ops;
252	case NFT_FIB_RESULT_ADDRTYPE:
253		return &nft_fib6_type_ops;
254	default:
255		return ERR_PTR(-EOPNOTSUPP);
256	}
257}
258
259static struct nft_expr_type nft_fib6_type __read_mostly = {
260	.name		= "fib",
261	.select_ops	= nft_fib6_select_ops,
262	.policy		= nft_fib_policy,
263	.maxattr	= NFTA_FIB_MAX,
264	.family		= NFPROTO_IPV6,
265	.owner		= THIS_MODULE,
266};
267
268static int __init nft_fib6_module_init(void)
269{
270	return nft_register_expr(&nft_fib6_type);
271}
272
273static void __exit nft_fib6_module_exit(void)
274{
275	nft_unregister_expr(&nft_fib6_type);
276}
277module_init(nft_fib6_module_init);
278module_exit(nft_fib6_module_exit);
279
280MODULE_LICENSE("GPL");
281MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
282MODULE_ALIAS_NFT_AF_EXPR(10, "fib");
283MODULE_DESCRIPTION("nftables fib / ipv6 route lookup support");
284