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/inet_dscp.h>
14 #include <net/ip_fib.h>
15 #include <net/route.h>
16
17 /* don't try to find route from mcast/bcast/zeronet */
get_saddr(__be32 addr)18 static __be32 get_saddr(__be32 addr)
19 {
20 if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
21 ipv4_is_zeronet(addr))
22 return 0;
23 return addr;
24 }
25
nft_fib4_eval_type(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)26 void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs,
27 const struct nft_pktinfo *pkt)
28 {
29 const struct nft_fib *priv = nft_expr_priv(expr);
30 int noff = skb_network_offset(pkt->skb);
31 u32 *dst = ®s->data[priv->dreg];
32 const struct net_device *dev = NULL;
33 struct iphdr *iph, _iph;
34 __be32 addr;
35
36 if (priv->flags & NFTA_FIB_F_IIF)
37 dev = nft_in(pkt);
38 else if (priv->flags & NFTA_FIB_F_OIF)
39 dev = nft_out(pkt);
40
41 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
42 if (!iph) {
43 regs->verdict.code = NFT_BREAK;
44 return;
45 }
46
47 if (priv->flags & NFTA_FIB_F_DADDR)
48 addr = iph->daddr;
49 else
50 addr = iph->saddr;
51
52 if (priv->flags & (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF)) {
53 *dst = inet_dev_addr_type(nft_net(pkt), dev, addr);
54 return;
55 }
56
57 *dst = inet_addr_type_dev_table(nft_net(pkt), pkt->skb->dev, addr);
58 }
59 EXPORT_SYMBOL_GPL(nft_fib4_eval_type);
60
nft_fib4_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)61 void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
62 const struct nft_pktinfo *pkt)
63 {
64 const struct nft_fib *priv = nft_expr_priv(expr);
65 int noff = skb_network_offset(pkt->skb);
66 u32 *dest = ®s->data[priv->dreg];
67 struct iphdr *iph, _iph;
68 struct fib_result res;
69 struct flowi4 fl4 = {
70 .flowi4_scope = RT_SCOPE_UNIVERSE,
71 .flowi4_iif = LOOPBACK_IFINDEX,
72 .flowi4_proto = pkt->tprot,
73 .flowi4_uid = sock_net_uid(nft_net(pkt), NULL),
74 };
75 const struct net_device *oif;
76 const struct net_device *found;
77
78 if (nft_fib_can_skip(pkt)) {
79 nft_fib_store_result(dest, priv, nft_in(pkt));
80 return;
81 }
82
83 /*
84 * Do not set flowi4_oif, it restricts results (for example, asking
85 * for oif 3 will get RTN_UNICAST result even if the daddr exits
86 * on another interface.
87 *
88 * Search results for the desired outinterface instead.
89 */
90 if (priv->flags & NFTA_FIB_F_OIF)
91 oif = nft_out(pkt);
92 else if (priv->flags & NFTA_FIB_F_IIF)
93 oif = nft_in(pkt);
94 else
95 oif = NULL;
96
97 fl4.flowi4_l3mdev = nft_fib_l3mdev_master_ifindex_rcu(pkt, oif);
98
99 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
100 if (!iph) {
101 regs->verdict.code = NFT_BREAK;
102 return;
103 }
104
105 if (ipv4_is_zeronet(iph->saddr)) {
106 if (ipv4_is_lbcast(iph->daddr) ||
107 ipv4_is_local_multicast(iph->daddr)) {
108 nft_fib_store_result(dest, priv, pkt->skb->dev);
109 return;
110 }
111 }
112
113 if (priv->flags & NFTA_FIB_F_MARK)
114 fl4.flowi4_mark = pkt->skb->mark;
115
116 fl4.flowi4_tos = iph->tos & INET_DSCP_MASK;
117
118 if (priv->flags & NFTA_FIB_F_DADDR) {
119 fl4.daddr = iph->daddr;
120 fl4.saddr = get_saddr(iph->saddr);
121 } else {
122 if (nft_hook(pkt) == NF_INET_FORWARD &&
123 priv->flags & NFTA_FIB_F_IIF)
124 fl4.flowi4_iif = nft_out(pkt)->ifindex;
125
126 fl4.daddr = iph->saddr;
127 fl4.saddr = get_saddr(iph->daddr);
128 }
129
130 *dest = 0;
131
132 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
133 return;
134
135 switch (res.type) {
136 case RTN_UNICAST:
137 break;
138 case RTN_LOCAL: /* Should not see RTN_LOCAL here */
139 return;
140 default:
141 break;
142 }
143
144 if (!oif) {
145 found = FIB_RES_DEV(res);
146 } else {
147 if (!fib_info_nh_uses_dev(res.fi, oif))
148 return;
149 found = oif;
150 }
151
152 nft_fib_store_result(dest, priv, found);
153 }
154 EXPORT_SYMBOL_GPL(nft_fib4_eval);
155
156 static struct nft_expr_type nft_fib4_type;
157
158 static const struct nft_expr_ops nft_fib4_type_ops = {
159 .type = &nft_fib4_type,
160 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
161 .eval = nft_fib4_eval_type,
162 .init = nft_fib_init,
163 .dump = nft_fib_dump,
164 .validate = nft_fib_validate,
165 .reduce = nft_fib_reduce,
166 };
167
168 static const struct nft_expr_ops nft_fib4_ops = {
169 .type = &nft_fib4_type,
170 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)),
171 .eval = nft_fib4_eval,
172 .init = nft_fib_init,
173 .dump = nft_fib_dump,
174 .validate = nft_fib_validate,
175 .reduce = nft_fib_reduce,
176 };
177
178 static const struct nft_expr_ops *
nft_fib4_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])179 nft_fib4_select_ops(const struct nft_ctx *ctx,
180 const struct nlattr * const tb[])
181 {
182 enum nft_fib_result result;
183
184 if (!tb[NFTA_FIB_RESULT])
185 return ERR_PTR(-EINVAL);
186
187 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
188
189 switch (result) {
190 case NFT_FIB_RESULT_OIF:
191 return &nft_fib4_ops;
192 case NFT_FIB_RESULT_OIFNAME:
193 return &nft_fib4_ops;
194 case NFT_FIB_RESULT_ADDRTYPE:
195 return &nft_fib4_type_ops;
196 default:
197 return ERR_PTR(-EOPNOTSUPP);
198 }
199 }
200
201 static struct nft_expr_type nft_fib4_type __read_mostly = {
202 .name = "fib",
203 .select_ops = nft_fib4_select_ops,
204 .policy = nft_fib_policy,
205 .maxattr = NFTA_FIB_MAX,
206 .family = NFPROTO_IPV4,
207 .owner = THIS_MODULE,
208 };
209
nft_fib4_module_init(void)210 static int __init nft_fib4_module_init(void)
211 {
212 return nft_register_expr(&nft_fib4_type);
213 }
214
nft_fib4_module_exit(void)215 static void __exit nft_fib4_module_exit(void)
216 {
217 nft_unregister_expr(&nft_fib4_type);
218 }
219
220 module_init(nft_fib4_module_init);
221 module_exit(nft_fib4_module_exit);
222 MODULE_LICENSE("GPL");
223 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
224 MODULE_ALIAS_NFT_AF_EXPR(2, "fib");
225 MODULE_DESCRIPTION("nftables fib / ip route lookup support");
226