1
2
3
4
5
6
7
8
9
10
11#include <linux/netfilter_bridge/ebtables.h>
12#include <linux/module.h>
13
14#define FILTER_VALID_HOOKS ((1 << NF_BR_LOCAL_IN) | (1 << NF_BR_FORWARD) | \
15 (1 << NF_BR_LOCAL_OUT))
16
17static struct ebt_entries initial_chains[] =
18{
19 {
20 .name = "INPUT",
21 .policy = EBT_ACCEPT,
22 },
23 {
24 .name = "FORWARD",
25 .policy = EBT_ACCEPT,
26 },
27 {
28 .name = "OUTPUT",
29 .policy = EBT_ACCEPT,
30 },
31};
32
33static struct ebt_replace_kernel initial_table =
34{
35 .name = "filter",
36 .valid_hooks = FILTER_VALID_HOOKS,
37 .entries_size = 3 * sizeof(struct ebt_entries),
38 .hook_entry = {
39 [NF_BR_LOCAL_IN] = &initial_chains[0],
40 [NF_BR_FORWARD] = &initial_chains[1],
41 [NF_BR_LOCAL_OUT] = &initial_chains[2],
42 },
43 .entries = (char *)initial_chains,
44};
45
46static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
47{
48 if (valid_hooks & ~FILTER_VALID_HOOKS)
49 return -EINVAL;
50 return 0;
51}
52
53static const struct ebt_table frame_filter =
54{
55 .name = "filter",
56 .table = &initial_table,
57 .valid_hooks = FILTER_VALID_HOOKS,
58 .check = check,
59 .me = THIS_MODULE,
60};
61
62static unsigned int
63ebt_in_hook(unsigned int hook, struct sk_buff *skb, const struct net_device *in,
64 const struct net_device *out, int (*okfn)(struct sk_buff *))
65{
66 return ebt_do_table(hook, skb, in, out, dev_net(in)->xt.frame_filter);
67}
68
69static unsigned int
70ebt_out_hook(unsigned int hook, struct sk_buff *skb, const struct net_device *in,
71 const struct net_device *out, int (*okfn)(struct sk_buff *))
72{
73 return ebt_do_table(hook, skb, in, out, dev_net(out)->xt.frame_filter);
74}
75
76static struct nf_hook_ops ebt_ops_filter[] __read_mostly = {
77 {
78 .hook = ebt_in_hook,
79 .owner = THIS_MODULE,
80 .pf = NFPROTO_BRIDGE,
81 .hooknum = NF_BR_LOCAL_IN,
82 .priority = NF_BR_PRI_FILTER_BRIDGED,
83 },
84 {
85 .hook = ebt_in_hook,
86 .owner = THIS_MODULE,
87 .pf = NFPROTO_BRIDGE,
88 .hooknum = NF_BR_FORWARD,
89 .priority = NF_BR_PRI_FILTER_BRIDGED,
90 },
91 {
92 .hook = ebt_out_hook,
93 .owner = THIS_MODULE,
94 .pf = NFPROTO_BRIDGE,
95 .hooknum = NF_BR_LOCAL_OUT,
96 .priority = NF_BR_PRI_FILTER_OTHER,
97 },
98};
99
100static int __net_init frame_filter_net_init(struct net *net)
101{
102 net->xt.frame_filter = ebt_register_table(net, &frame_filter);
103 return PTR_RET(net->xt.frame_filter);
104}
105
106static void __net_exit frame_filter_net_exit(struct net *net)
107{
108 ebt_unregister_table(net, net->xt.frame_filter);
109}
110
111static struct pernet_operations frame_filter_net_ops = {
112 .init = frame_filter_net_init,
113 .exit = frame_filter_net_exit,
114};
115
116static int __init ebtable_filter_init(void)
117{
118 int ret;
119
120 ret = register_pernet_subsys(&frame_filter_net_ops);
121 if (ret < 0)
122 return ret;
123 ret = nf_register_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
124 if (ret < 0)
125 unregister_pernet_subsys(&frame_filter_net_ops);
126 return ret;
127}
128
129static void __exit ebtable_filter_fini(void)
130{
131 nf_unregister_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
132 unregister_pernet_subsys(&frame_filter_net_ops);
133}
134
135module_init(ebtable_filter_init);
136module_exit(ebtable_filter_fini);
137MODULE_LICENSE("GPL");
138
