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