nft_fib_ipv6.c

  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	}
 45
 46	if (ipv6_addr_type(&fl6->saddr) & IPV6_ADDR_UNICAST)
 47		lookup_flags |= RT6_LOOKUP_F_HAS_SADDR;
 48
 49	if (priv->flags & NFTA_FIB_F_MARK)
 50		fl6->flowi6_mark = pkt->skb->mark;
 51
 52	fl6->flowlabel = (*(__be32 *)iph) & IPV6_FLOWINFO_MASK;
 53	fl6->flowi6_l3mdev = nft_fib_l3mdev_master_ifindex_rcu(pkt, dev);
 54
 55	return lookup_flags;
 56}
 57
 58static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
 59				const struct nft_pktinfo *pkt,
 60				struct ipv6hdr *iph)
 61{
 62	const struct net_device *dev = NULL;
 63	int route_err, addrtype;
 64	struct rt6_info *rt;
 65	struct flowi6 fl6 = {
 66		.flowi6_iif = LOOPBACK_IFINDEX,
 67		.flowi6_proto = pkt->tprot,
 68		.flowi6_uid = sock_net_uid(nft_net(pkt), NULL),
 69	};
 70	u32 ret = 0;
 71
 72	if (priv->flags & NFTA_FIB_F_IIF)
 73		dev = nft_in(pkt);
 74	else if (priv->flags & NFTA_FIB_F_OIF)
 75		dev = nft_out(pkt);
 76
 77	nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
 78
 79	if (dev && nf_ipv6_chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
 80		ret = RTN_LOCAL;
 81
 82	route_err = nf_ip6_route(nft_net(pkt), (struct dst_entry **)&rt,
 83				 flowi6_to_flowi(&fl6), false);
 84	if (route_err)
 85		goto err;
 86
 87	if (rt->rt6i_flags & RTF_REJECT) {
 88		route_err = rt->dst.error;
 89		dst_release(&rt->dst);
 90		goto err;
 91	}
 92
 93	if (ipv6_anycast_destination((struct dst_entry *)rt, &fl6.daddr))
 94		ret = RTN_ANYCAST;
 95	else if (!dev && rt->rt6i_flags & RTF_LOCAL)
 96		ret = RTN_LOCAL;
 97
 98	dst_release(&rt->dst);
 99
100	if (ret)
101		return ret;
102
103	addrtype = ipv6_addr_type(&fl6.daddr);
104
105	if (addrtype & IPV6_ADDR_MULTICAST)
106		return RTN_MULTICAST;
107	if (addrtype & IPV6_ADDR_UNICAST)
108		return RTN_UNICAST;
109
110	return RTN_UNSPEC;
111 err:
112	switch (route_err) {
113	case -EINVAL:
114		return RTN_BLACKHOLE;
115	case -EACCES:
116		return RTN_PROHIBIT;
117	case -EAGAIN:
118		return RTN_THROW;
119	default:
120		break;
121	}
122
123	return RTN_UNREACHABLE;
124}
125
126void nft_fib6_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
127			const struct nft_pktinfo *pkt)
128{
129	const struct nft_fib *priv = nft_expr_priv(expr);
130	int noff = skb_network_offset(pkt->skb);
131	u32 *dest = &regs->data[priv->dreg];
132	struct ipv6hdr *iph, _iph;
133
134	iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
135	if (!iph) {
136		regs->verdict.code = NFT_BREAK;
137		return;
138	}
139
140	*dest = __nft_fib6_eval_type(priv, pkt, iph);
141}
142EXPORT_SYMBOL_GPL(nft_fib6_eval_type);
143
144static bool nft_fib_v6_skip_icmpv6(const struct sk_buff *skb, u8 next, const struct ipv6hdr *iph)
145{
146	if (likely(next != IPPROTO_ICMPV6))
147		return false;
148
149	if (ipv6_addr_type(&iph->saddr) != IPV6_ADDR_ANY)
150		return false;
151
152	return ipv6_addr_type(&iph->daddr) & IPV6_ADDR_LINKLOCAL;
153}
154
155void nft_fib6_eval(const struct nft_expr *expr, struct nft_regs *regs,
156		   const struct nft_pktinfo *pkt)
157{
158	const struct nft_fib *priv = nft_expr_priv(expr);
159	int noff = skb_network_offset(pkt->skb);
160	const struct net_device *found = NULL;
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 (nft_fib_can_skip(pkt)) {
173		nft_fib_store_result(dest, priv, nft_in(pkt));
174		return;
175	}
176
177	if (priv->flags & NFTA_FIB_F_IIF)
178		oif = nft_in(pkt);
179	else if (priv->flags & NFTA_FIB_F_OIF)
180		oif = nft_out(pkt);
181
182	iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
183	if (!iph) {
184		regs->verdict.code = NFT_BREAK;
185		return;
186	}
187
188	if (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	lookup_flags = nft_fib6_flowi_init(&fl6, priv, pkt, oif, iph);
194
195	*dest = 0;
196	rt = (void *)ip6_route_lookup(nft_net(pkt), &fl6, pkt->skb,
197				      lookup_flags);
198	if (rt->dst.error)
199		goto put_rt_err;
200
201	/* Should not see RTF_LOCAL here */
202	if (rt->rt6i_flags & (RTF_REJECT | RTF_ANYCAST | RTF_LOCAL))
203		goto put_rt_err;
204
205	if (!oif) {
206		found = rt->rt6i_idev->dev;
207	} else {
208		if (oif == rt->rt6i_idev->dev ||
209		    l3mdev_master_ifindex_rcu(rt->rt6i_idev->dev) == oif->ifindex)
210			found = oif;
211	}
212
213	nft_fib_store_result(dest, priv, found);
214 put_rt_err:
215	ip6_rt_put(rt);
216}
217EXPORT_SYMBOL_GPL(nft_fib6_eval);
218
219static struct nft_expr_type nft_fib6_type;
220
221static const struct nft_expr_ops nft_fib6_type_ops = {
222	.type		= &nft_fib6_type,
223	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
224	.eval		= nft_fib6_eval_type,
225	.init		= nft_fib_init,
226	.dump		= nft_fib_dump,
227	.validate	= nft_fib_validate,
228	.reduce		= nft_fib_reduce,
229};
230
231static const struct nft_expr_ops nft_fib6_ops = {
232	.type		= &nft_fib6_type,
233	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
234	.eval		= nft_fib6_eval,
235	.init		= nft_fib_init,
236	.dump		= nft_fib_dump,
237	.validate	= nft_fib_validate,
238	.reduce		= nft_fib_reduce,
239};
240
241static const struct nft_expr_ops *
242nft_fib6_select_ops(const struct nft_ctx *ctx,
243		    const struct nlattr * const tb[])
244{
245	enum nft_fib_result result;
246
247	if (!tb[NFTA_FIB_RESULT])
248		return ERR_PTR(-EINVAL);
249
250	result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
251
252	switch (result) {
253	case NFT_FIB_RESULT_OIF:
254		return &nft_fib6_ops;
255	case NFT_FIB_RESULT_OIFNAME:
256		return &nft_fib6_ops;
257	case NFT_FIB_RESULT_ADDRTYPE:
258		return &nft_fib6_type_ops;
259	default:
260		return ERR_PTR(-EOPNOTSUPP);
261	}
262}
263
264static struct nft_expr_type nft_fib6_type __read_mostly = {
265	.name		= "fib",
266	.select_ops	= nft_fib6_select_ops,
267	.policy		= nft_fib_policy,
268	.maxattr	= NFTA_FIB_MAX,
269	.family		= NFPROTO_IPV6,
270	.owner		= THIS_MODULE,
271};
272
273static int __init nft_fib6_module_init(void)
274{
275	return nft_register_expr(&nft_fib6_type);
276}
277
278static void __exit nft_fib6_module_exit(void)
279{
280	nft_unregister_expr(&nft_fib6_type);
281}
282module_init(nft_fib6_module_init);
283module_exit(nft_fib6_module_exit);
284
285MODULE_LICENSE("GPL");
286MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
287MODULE_ALIAS_NFT_AF_EXPR(10, "fib");
288MODULE_DESCRIPTION("nftables fib / ipv6 route lookup support");