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 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 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 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 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 } 101 102 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 }; 111 112 static int __init ebtable_nat_init(void) 113 { 114 return register_pernet_subsys(&frame_nat_net_ops); 115 } 116 117 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