1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ebtable_nat
4 *
5 * Authors:
6 * Bart De Schuymer <bdschuym@pandora.be>
7 *
8 * April, 2002
9 *
10 */
11
12 #include <linux/netfilter_bridge/ebtables.h>
13 #include <uapi/linux/netfilter_bridge.h>
14 #include <linux/module.h>
15
16 #define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
17 (1 << NF_BR_POST_ROUTING))
18
19 static struct ebt_entries initial_chains[] = {
20 {
21 .name = "PREROUTING",
22 .policy = EBT_ACCEPT,
23 },
24 {
25 .name = "OUTPUT",
26 .policy = EBT_ACCEPT,
27 },
28 {
29 .name = "POSTROUTING",
30 .policy = EBT_ACCEPT,
31 }
32 };
33
34 static struct ebt_replace_kernel initial_table = {
35 .name = "nat",
36 .valid_hooks = NAT_VALID_HOOKS,
37 .entries_size = 3 * sizeof(struct ebt_entries),
38 .hook_entry = {
39 [NF_BR_PRE_ROUTING] = &initial_chains[0],
40 [NF_BR_LOCAL_OUT] = &initial_chains[1],
41 [NF_BR_POST_ROUTING] = &initial_chains[2],
42 },
43 .entries = (char *)initial_chains,
44 };
45
check(const struct ebt_table_info * info,unsigned int valid_hooks)46 static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
47 {
48 if (valid_hooks & ~NAT_VALID_HOOKS)
49 return -EINVAL;
50 return 0;
51 }
52
53 static const struct ebt_table frame_nat = {
54 .name = "nat",
55 .table = &initial_table,
56 .valid_hooks = NAT_VALID_HOOKS,
57 .check = check,
58 .me = THIS_MODULE,
59 };
60
61 static unsigned int
ebt_nat_in(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)62 ebt_nat_in(void *priv, struct sk_buff *skb,
63 const struct nf_hook_state *state)
64 {
65 return ebt_do_table(skb, state, state->net->xt.frame_nat);
66 }
67
68 static unsigned int
ebt_nat_out(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)69 ebt_nat_out(void *priv, struct sk_buff *skb,
70 const struct nf_hook_state *state)
71 {
72 return ebt_do_table(skb, state, state->net->xt.frame_nat);
73 }
74
75 static const struct nf_hook_ops ebt_ops_nat[] = {
76 {
77 .hook = ebt_nat_out,
78 .pf = NFPROTO_BRIDGE,
79 .hooknum = NF_BR_LOCAL_OUT,
80 .priority = NF_BR_PRI_NAT_DST_OTHER,
81 },
82 {
83 .hook = ebt_nat_out,
84 .pf = NFPROTO_BRIDGE,
85 .hooknum = NF_BR_POST_ROUTING,
86 .priority = NF_BR_PRI_NAT_SRC,
87 },
88 {
89 .hook = ebt_nat_in,
90 .pf = NFPROTO_BRIDGE,
91 .hooknum = NF_BR_PRE_ROUTING,
92 .priority = NF_BR_PRI_NAT_DST_BRIDGED,
93 },
94 };
95
frame_nat_net_init(struct net * net)96 static int __net_init frame_nat_net_init(struct net *net)
97 {
98 return ebt_register_table(net, &frame_nat, ebt_ops_nat,
99 &net->xt.frame_nat);
100 }
101
frame_nat_net_exit(struct net * net)102 static void __net_exit frame_nat_net_exit(struct net *net)
103 {
104 ebt_unregister_table(net, net->xt.frame_nat, ebt_ops_nat);
105 }
106
107 static struct pernet_operations frame_nat_net_ops = {
108 .init = frame_nat_net_init,
109 .exit = frame_nat_net_exit,
110 };
111
ebtable_nat_init(void)112 static int __init ebtable_nat_init(void)
113 {
114 return register_pernet_subsys(&frame_nat_net_ops);
115 }
116
ebtable_nat_fini(void)117 static void __exit ebtable_nat_fini(void)
118 {
119 unregister_pernet_subsys(&frame_nat_net_ops);
120 }
121
122 module_init(ebtable_nat_init);
123 module_exit(ebtable_nat_fini);
124 MODULE_LICENSE("GPL");
125
