Linux Kernel  3.7.1
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ebtable_filter.c
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1 /*
2  * ebtable_filter
3  *
4  * Authors:
5  * Bart De Schuymer <[email protected]>
6  *
7  * April, 2002
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 
17 static 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 
33 static 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 
46 static 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 
53 static const struct ebt_table frame_filter =
54 {
55  .name = "filter",
56  .table = &initial_table,
58  .check = check,
59  .me = THIS_MODULE,
60 };
61 
62 static unsigned int
63 ebt_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 
69 static unsigned int
70 ebt_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 
76 static 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 
100 static 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 
106 static void __net_exit frame_filter_net_exit(struct net *net)
107 {
108  ebt_unregister_table(net, net->xt.frame_filter);
109 }
110 
111 static struct pernet_operations frame_filter_net_ops = {
112  .init = frame_filter_net_init,
113  .exit = frame_filter_net_exit,
114 };
115 
116 static 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 
129 static 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 
135 module_init(ebtable_filter_init);
136 module_exit(ebtable_filter_fini);
137 MODULE_LICENSE("GPL");