1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x. |
4 | * |
5 | * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling |
6 | * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> |
7 | */ |
8 | |
9 | #include <linux/module.h> |
10 | #include <linux/moduleparam.h> |
11 | #include <linux/netfilter_ipv4/ip_tables.h> |
12 | #include <linux/slab.h> |
13 | #include <net/ip.h> |
14 | |
15 | MODULE_LICENSE("GPL" ); |
16 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>" ); |
17 | MODULE_DESCRIPTION("iptables filter table" ); |
18 | |
19 | #define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \ |
20 | (1 << NF_INET_FORWARD) | \ |
21 | (1 << NF_INET_LOCAL_OUT)) |
22 | |
23 | static const struct xt_table packet_filter = { |
24 | .name = "filter" , |
25 | .valid_hooks = FILTER_VALID_HOOKS, |
26 | .me = THIS_MODULE, |
27 | .af = NFPROTO_IPV4, |
28 | .priority = NF_IP_PRI_FILTER, |
29 | }; |
30 | |
31 | static struct nf_hook_ops *filter_ops __read_mostly; |
32 | |
33 | /* Default to forward because I got too much mail already. */ |
34 | static bool forward __read_mostly = true; |
35 | module_param(forward, bool, 0000); |
36 | |
37 | static int iptable_filter_table_init(struct net *net) |
38 | { |
39 | struct ipt_replace *repl; |
40 | int err; |
41 | |
42 | repl = ipt_alloc_initial_table(&packet_filter); |
43 | if (repl == NULL) |
44 | return -ENOMEM; |
45 | /* Entry 1 is the FORWARD hook */ |
46 | ((struct ipt_standard *)repl->entries)[1].target.verdict = |
47 | forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; |
48 | |
49 | err = ipt_register_table(net, table: &packet_filter, repl, ops: filter_ops); |
50 | kfree(objp: repl); |
51 | return err; |
52 | } |
53 | |
54 | static int __net_init iptable_filter_net_init(struct net *net) |
55 | { |
56 | if (!forward) |
57 | return iptable_filter_table_init(net); |
58 | |
59 | return 0; |
60 | } |
61 | |
62 | static void __net_exit iptable_filter_net_pre_exit(struct net *net) |
63 | { |
64 | ipt_unregister_table_pre_exit(net, name: "filter" ); |
65 | } |
66 | |
67 | static void __net_exit iptable_filter_net_exit(struct net *net) |
68 | { |
69 | ipt_unregister_table_exit(net, name: "filter" ); |
70 | } |
71 | |
72 | static struct pernet_operations iptable_filter_net_ops = { |
73 | .init = iptable_filter_net_init, |
74 | .pre_exit = iptable_filter_net_pre_exit, |
75 | .exit = iptable_filter_net_exit, |
76 | }; |
77 | |
78 | static int __init iptable_filter_init(void) |
79 | { |
80 | int ret = xt_register_template(t: &packet_filter, |
81 | table_init: iptable_filter_table_init); |
82 | |
83 | if (ret < 0) |
84 | return ret; |
85 | |
86 | filter_ops = xt_hook_ops_alloc(&packet_filter, ipt_do_table); |
87 | if (IS_ERR(ptr: filter_ops)) { |
88 | xt_unregister_template(t: &packet_filter); |
89 | return PTR_ERR(ptr: filter_ops); |
90 | } |
91 | |
92 | ret = register_pernet_subsys(&iptable_filter_net_ops); |
93 | if (ret < 0) { |
94 | xt_unregister_template(t: &packet_filter); |
95 | kfree(objp: filter_ops); |
96 | return ret; |
97 | } |
98 | |
99 | return 0; |
100 | } |
101 | |
102 | static void __exit iptable_filter_fini(void) |
103 | { |
104 | unregister_pernet_subsys(&iptable_filter_net_ops); |
105 | xt_unregister_template(t: &packet_filter); |
106 | kfree(objp: filter_ops); |
107 | } |
108 | |
109 | module_init(iptable_filter_init); |
110 | module_exit(iptable_filter_fini); |
111 | |