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 <net/netfilter/nf_tables_core.h>
10 #include <net/netfilter/nf_tables.h>
11 #include <net/netfilter/nft_fib.h>
12
13 #include <net/ip_fib.h>
14 #include <net/route.h>
15
16 /* don't try to find route from mcast/bcast/zeronet */
get_saddr(__be32 addr)17 static __be32 get_saddr(__be32 addr)
18 {
19 if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
20 ipv4_is_zeronet(addr))
21 return 0;
22 return addr;
23 }
24
25 #define DSCP_BITS 0xfc
26
nft_fib4_eval_type(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)27 void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
28 const struct nft_pktinfo *pkt)
29 {
30 const struct nft_fib *priv = nft_expr_priv(expr);
31 int noff = skb_network_offset(pkt->skb);
32 u32 *dst = ®s->data[priv->dreg];
33 const struct net_device *dev = NULL;
34 struct iphdr *iph, _iph;
35 __be32 addr;
36
37 if (priv->flags & NFTA_FIB_F_IIF)
38 dev = nft_in(pkt);
39 else if (priv->flags & NFTA_FIB_F_OIF)
40 dev = nft_out(pkt);
41
42 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
43 if (!iph) {
44 regs->verdict.code = NFT_BREAK;
45 return;
46 }
47
48 if (priv->flags & NFTA_FIB_F_DADDR)
49 addr = iph->daddr;
50 else
51 addr = iph->saddr;
52
53 *dst = inet_dev_addr_type(nft_net(pkt), dev, addr);
54 }
55 EXPORT_SYMBOL_GPL(nft_fib4_eval_type);
56
nft_fib4_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)57 void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
58 const struct nft_pktinfo *pkt)
59 {
60 const struct nft_fib *priv = nft_expr_priv(expr);
61 int noff = skb_network_offset(pkt->skb);
62 u32 *dest = ®s->data[priv->dreg];
63 struct iphdr *iph, _iph;
64 struct fib_result res;
65 struct flowi4 fl4 = {
66 .flowi4_scope = RT_SCOPE_UNIVERSE,
67 .flowi4_iif = LOOPBACK_IFINDEX,
68 };
69 const struct net_device *oif;
70 const struct net_device *found;
71
72 /*
73 * Do not set flowi4_oif, it restricts results (for example, asking
74 * for oif 3 will get RTN_UNICAST result even if the daddr exits
75 * on another interface.
76 *
77 * Search results for the desired outinterface instead.
78 */
79 if (priv->flags & NFTA_FIB_F_OIF)
80 oif = nft_out(pkt);
81 else if (priv->flags & NFTA_FIB_F_IIF)
82 oif = nft_in(pkt);
83 else
84 oif = NULL;
85
86 if (priv->flags & NFTA_FIB_F_IIF)
87 fl4.flowi4_oif = l3mdev_master_ifindex_rcu(oif);
88
89 if (nft_hook(pkt) == NF_INET_PRE_ROUTING &&
90 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) {
91 nft_fib_store_result(dest, priv, nft_in(pkt));
92 return;
93 }
94
95 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
96 if (!iph) {
97 regs->verdict.code = NFT_BREAK;
98 return;
99 }
100
101 if (ipv4_is_zeronet(iph->saddr)) {
102 if (ipv4_is_lbcast(iph->daddr) ||
103 ipv4_is_local_multicast(iph->daddr)) {
104 nft_fib_store_result(dest, priv, pkt->skb->dev);
105 return;
106 }
107 }
108
109 if (priv->flags & NFTA_FIB_F_MARK)
110 fl4.flowi4_mark = pkt->skb->mark;
111
112 fl4.flowi4_tos = iph->tos & DSCP_BITS;
113
114 if (priv->flags & NFTA_FIB_F_DADDR) {
115 fl4.daddr = iph->daddr;
116 fl4.saddr = get_saddr(iph->saddr);
117 } else {
118 fl4.daddr = iph->saddr;
119 fl4.saddr = get_saddr(iph->daddr);
120 }
121
122 *dest = 0;
123
124 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
125 return;
126
127 switch (res.type) {
128 case RTN_UNICAST:
129 break;
130 case RTN_LOCAL: /* Should not see RTN_LOCAL here */
131 return;
132 default:
133 break;
134 }
135
136 if (!oif) {
137 found = FIB_RES_DEV(res);
138 } else {
139 if (!fib_info_nh_uses_dev(res.fi, oif))
140 return;
141
142 found = oif;
143 }
144
145 nft_fib_store_result(dest, priv, found);
146 }
147 EXPORT_SYMBOL_GPL(nft_fib4_eval);
148
149 static struct nft_expr_type nft_fib4_type;
150
151 static const struct nft_expr_ops nft_fib4_type_ops = {
152 .type = &nft_fib4_type,
153 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
154 .eval = nft_fib4_eval_type,
155 .init = nft_fib_init,
156 .dump = nft_fib_dump,
157 .validate = nft_fib_validate,
158 };
159
160 static const struct nft_expr_ops nft_fib4_ops = {
161 .type = &nft_fib4_type,
162 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
163 .eval = nft_fib4_eval,
164 .init = nft_fib_init,
165 .dump = nft_fib_dump,
166 .validate = nft_fib_validate,
167 };
168
169 static const struct nft_expr_ops *
nft_fib4_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])170 nft_fib4_select_ops(const struct nft_ctx *ctx,
171 const struct nlattr * const tb[])
172 {
173 enum nft_fib_result result;
174
175 if (!tb[NFTA_FIB_RESULT])
176 return ERR_PTR(-EINVAL);
177
178 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
179
180 switch (result) {
181 case NFT_FIB_RESULT_OIF:
182 return &nft_fib4_ops;
183 case NFT_FIB_RESULT_OIFNAME:
184 return &nft_fib4_ops;
185 case NFT_FIB_RESULT_ADDRTYPE:
186 return &nft_fib4_type_ops;
187 default:
188 return ERR_PTR(-EOPNOTSUPP);
189 }
190 }
191
192 static struct nft_expr_type nft_fib4_type __read_mostly = {
193 .name = "fib",
194 .select_ops = nft_fib4_select_ops,
195 .policy = nft_fib_policy,
196 .maxattr = NFTA_FIB_MAX,
197 .family = NFPROTO_IPV4,
198 .owner = THIS_MODULE,
199 };
200
nft_fib4_module_init(void)201 static int __init nft_fib4_module_init(void)
202 {
203 return nft_register_expr(&nft_fib4_type);
204 }
205
nft_fib4_module_exit(void)206 static void __exit nft_fib4_module_exit(void)
207 {
208 nft_unregister_expr(&nft_fib4_type);
209 }
210
211 module_init(nft_fib4_module_init);
212 module_exit(nft_fib4_module_exit);
213 MODULE_LICENSE("GPL");
214 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
215 MODULE_ALIAS_NFT_AF_EXPR(2, "fib");
216 MODULE_DESCRIPTION("nftables fib / ip route lookup support");
217