1 /*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License version 2 as
4 * published by the Free Software Foundation.
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/init.h>
9 #include <linux/module.h>
10 #include <linux/netlink.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter/nf_tables.h>
13 #include <net/netfilter/nf_tables_core.h>
14 #include <net/netfilter/nf_tables.h>
15 #include <net/netfilter/nft_fib.h>
16
17 #include <net/ip_fib.h>
18 #include <net/route.h>
19
20 /* don't try to find route from mcast/bcast/zeronet */
21 static __be32 get_saddr(__be32 addr)
22 {
23 if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
24 ipv4_is_zeronet(addr))
25 return 0;
26 return addr;
27 }
28
29 #define DSCP_BITS 0xfc
30
31 void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
32 const struct nft_pktinfo *pkt)
33 {
34 const struct nft_fib *priv = nft_expr_priv(expr);
35 int noff = skb_network_offset(pkt->skb);
36 u32 *dst = ®s->data[priv->dreg];
37 const struct net_device *dev = NULL;
38 struct iphdr *iph, _iph;
39 __be32 addr;
40
41 if (priv->flags & NFTA_FIB_F_IIF)
42 dev = nft_in(pkt);
43 else if (priv->flags & NFTA_FIB_F_OIF)
44 dev = nft_out(pkt);
45
46 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
47 if (!iph) {
48 regs->verdict.code = NFT_BREAK;
49 return;
50 }
51
52 if (priv->flags & NFTA_FIB_F_DADDR)
53 addr = iph->daddr;
54 else
55 addr = iph->saddr;
56
57 *dst = inet_dev_addr_type(nft_net(pkt), dev, addr);
58 }
59 EXPORT_SYMBOL_GPL(nft_fib4_eval_type);
60
61 static int get_ifindex(const struct net_device *dev)
62 {
63 return dev ? dev->ifindex : 0;
64 }
65
66 void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
67 const struct nft_pktinfo *pkt)
68 {
69 const struct nft_fib *priv = nft_expr_priv(expr);
70 int noff = skb_network_offset(pkt->skb);
71 u32 *dest = ®s->data[priv->dreg];
72 struct iphdr *iph, _iph;
73 struct fib_result res;
74 struct flowi4 fl4 = {
75 .flowi4_scope = RT_SCOPE_UNIVERSE,
76 .flowi4_iif = LOOPBACK_IFINDEX,
77 };
78 const struct net_device *oif;
79 struct net_device *found;
80 #ifdef CONFIG_IP_ROUTE_MULTIPATH
81 int i;
82 #endif
83
84 /*
85 * Do not set flowi4_oif, it restricts results (for example, asking
86 * for oif 3 will get RTN_UNICAST result even if the daddr exits
87 * on another interface.
88 *
89 * Search results for the desired outinterface instead.
90 */
91 if (priv->flags & NFTA_FIB_F_OIF)
92 oif = nft_out(pkt);
93 else if (priv->flags & NFTA_FIB_F_IIF)
94 oif = nft_in(pkt);
95 else
96 oif = NULL;
97
98 if (nft_hook(pkt) == NF_INET_PRE_ROUTING &&
99 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) {
100 nft_fib_store_result(dest, priv, pkt,
101 nft_in(pkt)->ifindex);
102 return;
103 }
104
105 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
106 if (!iph) {
107 regs->verdict.code = NFT_BREAK;
108 return;
109 }
110
111 if (ipv4_is_zeronet(iph->saddr)) {
112 if (ipv4_is_lbcast(iph->daddr) ||
113 ipv4_is_local_multicast(iph->daddr)) {
114 nft_fib_store_result(dest, priv, pkt,
115 get_ifindex(pkt->skb->dev));
116 return;
117 }
118 }
119
120 if (priv->flags & NFTA_FIB_F_MARK)
121 fl4.flowi4_mark = pkt->skb->mark;
122
123 fl4.flowi4_tos = iph->tos & DSCP_BITS;
124
125 if (priv->flags & NFTA_FIB_F_DADDR) {
126 fl4.daddr = iph->daddr;
127 fl4.saddr = get_saddr(iph->saddr);
128 } else {
129 fl4.daddr = iph->saddr;
130 fl4.saddr = get_saddr(iph->daddr);
131 }
132
133 *dest = 0;
134
135 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
136 return;
137
138 switch (res.type) {
139 case RTN_UNICAST:
140 break;
141 case RTN_LOCAL: /* Should not see RTN_LOCAL here */
142 return;
143 default:
144 break;
145 }
146
147 if (!oif) {
148 found = FIB_RES_DEV(res);
149 goto ok;
150 }
151
152 #ifdef CONFIG_IP_ROUTE_MULTIPATH
153 for (i = 0; i < res.fi->fib_nhs; i++) {
154 struct fib_nh *nh = &res.fi->fib_nh[i];
155
156 if (nh->nh_dev == oif) {
157 found = nh->nh_dev;
158 goto ok;
159 }
160 }
161 return;
162 #else
163 found = FIB_RES_DEV(res);
164 if (found != oif)
165 return;
166 #endif
167 ok:
168 switch (priv->result) {
169 case NFT_FIB_RESULT_OIF:
170 *dest = found->ifindex;
171 break;
172 case NFT_FIB_RESULT_OIFNAME:
173 strncpy((char *)dest, found->name, IFNAMSIZ);
174 break;
175 default:
176 WARN_ON_ONCE(1);
177 break;
178 }
179 }
180 EXPORT_SYMBOL_GPL(nft_fib4_eval);
181
182 static struct nft_expr_type nft_fib4_type;
183
184 static const struct nft_expr_ops nft_fib4_type_ops = {
185 .type = &nft_fib4_type,
186 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
187 .eval = nft_fib4_eval_type,
188 .init = nft_fib_init,
189 .dump = nft_fib_dump,
190 .validate = nft_fib_validate,
191 };
192
193 static const struct nft_expr_ops nft_fib4_ops = {
194 .type = &nft_fib4_type,
195 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
196 .eval = nft_fib4_eval,
197 .init = nft_fib_init,
198 .dump = nft_fib_dump,
199 .validate = nft_fib_validate,
200 };
201
202 static const struct nft_expr_ops *
203 nft_fib4_select_ops(const struct nft_ctx *ctx,
204 const struct nlattr * const tb[])
205 {
206 enum nft_fib_result result;
207
208 if (!tb[NFTA_FIB_RESULT])
209 return ERR_PTR(-EINVAL);
210
211 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
212
213 switch (result) {
214 case NFT_FIB_RESULT_OIF:
215 return &nft_fib4_ops;
216 case NFT_FIB_RESULT_OIFNAME:
217 return &nft_fib4_ops;
218 case NFT_FIB_RESULT_ADDRTYPE:
219 return &nft_fib4_type_ops;
220 default:
221 return ERR_PTR(-EOPNOTSUPP);
222 }
223 }
224
225 static struct nft_expr_type nft_fib4_type __read_mostly = {
226 .name = "fib",
227 .select_ops = nft_fib4_select_ops,
228 .policy = nft_fib_policy,
229 .maxattr = NFTA_FIB_MAX,
230 .family = NFPROTO_IPV4,
231 .owner = THIS_MODULE,
232 };
233
234 static int __init nft_fib4_module_init(void)
235 {
236 return nft_register_expr(&nft_fib4_type);
237 }
238
239 static void __exit nft_fib4_module_exit(void)
240 {
241 nft_unregister_expr(&nft_fib4_type);
242 }
243
244 module_init(nft_fib4_module_init);
245 module_exit(nft_fib4_module_exit);
246 MODULE_LICENSE("GPL");
247 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
248 MODULE_ALIAS_NFT_AF_EXPR(2, "fib");
249
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