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
get_ifindex(const struct net_device * dev)17 static int get_ifindex(const struct net_device *dev)
18 {
19 return dev ? dev->ifindex : 0;
20 }
21
nft_fib6_flowi_init(struct flowi6 * fl6,const struct nft_fib * priv,const struct nft_pktinfo * pkt,const struct net_device * dev,struct ipv6hdr * iph)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 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
__nft_fib6_eval_type(const struct nft_fib * priv,const struct nft_pktinfo * pkt,struct ipv6hdr * iph)59 static 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
nft_fib6_eval_type(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)127 void 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 = ®s->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 }
143 EXPORT_SYMBOL_GPL(nft_fib6_eval_type);
144
nft_fib_v6_skip_icmpv6(const struct sk_buff * skb,u8 next,const struct ipv6hdr * iph)145 static 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
nft_fib6_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)156 void 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 = ®s->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 }
212 EXPORT_SYMBOL_GPL(nft_fib6_eval);
213
214 static struct nft_expr_type nft_fib6_type;
215
216 static 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
226 static 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
236 static const struct nft_expr_ops *
nft_fib6_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])237 nft_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
259 static 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
nft_fib6_module_init(void)268 static int __init nft_fib6_module_init(void)
269 {
270 return nft_register_expr(&nft_fib6_type);
271 }
272
nft_fib6_module_exit(void)273 static void __exit nft_fib6_module_exit(void)
274 {
275 nft_unregister_expr(&nft_fib6_type);
276 }
277 module_init(nft_fib6_module_init);
278 module_exit(nft_fib6_module_exit);
279
280 MODULE_LICENSE("GPL");
281 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
282 MODULE_ALIAS_NFT_AF_EXPR(10, "fib");
283 MODULE_DESCRIPTION("nftables fib / ipv6 route lookup support");
284