1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/skbuff.h>
4 #include <linux/netfilter.h>
5 #include <linux/netfilter_ipv4.h>
6 #include <linux/netfilter_ipv6.h>
7 #include <linux/netfilter/nfnetlink.h>
8 #include <linux/netfilter/nf_tables.h>
9 #include <net/netfilter/nf_tables.h>
10 #include <net/netfilter/nf_tables_ipv4.h>
11 #include <net/netfilter/nf_tables_ipv6.h>
12 #include <net/route.h>
13 #include <net/ip.h>
14
15 #ifdef CONFIG_NF_TABLES_IPV4
nf_route_table_hook4(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)16 static unsigned int nf_route_table_hook4(void *priv,
17 struct sk_buff *skb,
18 const struct nf_hook_state *state)
19 {
20 const struct iphdr *iph;
21 struct nft_pktinfo pkt;
22 __be32 saddr, daddr;
23 unsigned int ret;
24 u32 mark;
25 int err;
26 u8 tos;
27
28 nft_set_pktinfo(&pkt, skb, state);
29 nft_set_pktinfo_ipv4(&pkt, skb);
30
31 mark = skb->mark;
32 iph = ip_hdr(skb);
33 saddr = iph->saddr;
34 daddr = iph->daddr;
35 tos = iph->tos;
36
37 ret = nft_do_chain(&pkt, priv);
38 if (ret == NF_ACCEPT) {
39 iph = ip_hdr(skb);
40
41 if (iph->saddr != saddr ||
42 iph->daddr != daddr ||
43 skb->mark != mark ||
44 iph->tos != tos) {
45 err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
46 if (err < 0)
47 ret = NF_DROP_ERR(err);
48 }
49 }
50 return ret;
51 }
52
53 static const struct nft_chain_type nft_chain_route_ipv4 = {
54 .name = "route",
55 .type = NFT_CHAIN_T_ROUTE,
56 .family = NFPROTO_IPV4,
57 .hook_mask = (1 << NF_INET_LOCAL_OUT),
58 .hooks = {
59 [NF_INET_LOCAL_OUT] = nf_route_table_hook4,
60 },
61 };
62 #endif
63
64 #ifdef CONFIG_NF_TABLES_IPV6
nf_route_table_hook6(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)65 static unsigned int nf_route_table_hook6(void *priv,
66 struct sk_buff *skb,
67 const struct nf_hook_state *state)
68 {
69 struct in6_addr saddr, daddr;
70 struct nft_pktinfo pkt;
71 u32 mark, flowlabel;
72 unsigned int ret;
73 u8 hop_limit;
74 int err;
75
76 nft_set_pktinfo(&pkt, skb, state);
77 nft_set_pktinfo_ipv6(&pkt, skb);
78
79 /* save source/dest address, mark, hoplimit, flowlabel, priority */
80 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
81 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
82 mark = skb->mark;
83 hop_limit = ipv6_hdr(skb)->hop_limit;
84
85 /* flowlabel and prio (includes version, which shouldn't change either)*/
86 flowlabel = *((u32 *)ipv6_hdr(skb));
87
88 ret = nft_do_chain(&pkt, priv);
89 if (ret == NF_ACCEPT &&
90 (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
91 memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
92 skb->mark != mark ||
93 ipv6_hdr(skb)->hop_limit != hop_limit ||
94 flowlabel != *((u32 *)ipv6_hdr(skb)))) {
95 err = nf_ip6_route_me_harder(state->net, state->sk, skb);
96 if (err < 0)
97 ret = NF_DROP_ERR(err);
98 }
99
100 return ret;
101 }
102
103 static const struct nft_chain_type nft_chain_route_ipv6 = {
104 .name = "route",
105 .type = NFT_CHAIN_T_ROUTE,
106 .family = NFPROTO_IPV6,
107 .hook_mask = (1 << NF_INET_LOCAL_OUT),
108 .hooks = {
109 [NF_INET_LOCAL_OUT] = nf_route_table_hook6,
110 },
111 };
112 #endif
113
114 #ifdef CONFIG_NF_TABLES_INET
nf_route_table_inet(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)115 static unsigned int nf_route_table_inet(void *priv,
116 struct sk_buff *skb,
117 const struct nf_hook_state *state)
118 {
119 struct nft_pktinfo pkt;
120
121 switch (state->pf) {
122 case NFPROTO_IPV4:
123 return nf_route_table_hook4(priv, skb, state);
124 case NFPROTO_IPV6:
125 return nf_route_table_hook6(priv, skb, state);
126 default:
127 nft_set_pktinfo(&pkt, skb, state);
128 break;
129 }
130
131 return nft_do_chain(&pkt, priv);
132 }
133
134 static const struct nft_chain_type nft_chain_route_inet = {
135 .name = "route",
136 .type = NFT_CHAIN_T_ROUTE,
137 .family = NFPROTO_INET,
138 .hook_mask = (1 << NF_INET_LOCAL_OUT),
139 .hooks = {
140 [NF_INET_LOCAL_OUT] = nf_route_table_inet,
141 },
142 };
143 #endif
144
nft_chain_route_init(void)145 void __init nft_chain_route_init(void)
146 {
147 #ifdef CONFIG_NF_TABLES_IPV6
148 nft_register_chain_type(&nft_chain_route_ipv6);
149 #endif
150 #ifdef CONFIG_NF_TABLES_IPV4
151 nft_register_chain_type(&nft_chain_route_ipv4);
152 #endif
153 #ifdef CONFIG_NF_TABLES_INET
154 nft_register_chain_type(&nft_chain_route_inet);
155 #endif
156 }
157
nft_chain_route_fini(void)158 void __exit nft_chain_route_fini(void)
159 {
160 #ifdef CONFIG_NF_TABLES_IPV6
161 nft_unregister_chain_type(&nft_chain_route_ipv6);
162 #endif
163 #ifdef CONFIG_NF_TABLES_IPV4
164 nft_unregister_chain_type(&nft_chain_route_ipv4);
165 #endif
166 #ifdef CONFIG_NF_TABLES_INET
167 nft_unregister_chain_type(&nft_chain_route_inet);
168 #endif
169 }
170