1 /* Xtables module to match packets using a BPF filter.
2 * Copyright 2013 Google Inc.
3 * Written by Willem de Bruijn <willemb@google.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/filter.h>
13
14 #include <linux/netfilter/xt_bpf.h>
15 #include <linux/netfilter/x_tables.h>
16
17 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
18 MODULE_DESCRIPTION("Xtables: BPF filter match");
19 MODULE_LICENSE("GPL");
20 MODULE_ALIAS("ipt_bpf");
21 MODULE_ALIAS("ip6t_bpf");
22
bpf_mt_check(const struct xt_mtchk_param * par)23 static int bpf_mt_check(const struct xt_mtchk_param *par)
24 {
25 struct xt_bpf_info *info = par->matchinfo;
26 struct sock_fprog_kern program;
27
28 if (info->bpf_program_num_elem > XT_BPF_MAX_NUM_INSTR)
29 return -EINVAL;
30
31 program.len = info->bpf_program_num_elem;
32 program.filter = info->bpf_program;
33
34 if (bpf_prog_create(&info->filter, &program)) {
35 pr_info("bpf: check failed: parse error\n");
36 return -EINVAL;
37 }
38
39 return 0;
40 }
41
bpf_mt(const struct sk_buff * skb,struct xt_action_param * par)42 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
43 {
44 const struct xt_bpf_info *info = par->matchinfo;
45
46 return BPF_PROG_RUN(info->filter, skb);
47 }
48
bpf_mt_destroy(const struct xt_mtdtor_param * par)49 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
50 {
51 const struct xt_bpf_info *info = par->matchinfo;
52 bpf_prog_destroy(info->filter);
53 }
54
55 static struct xt_match bpf_mt_reg __read_mostly = {
56 .name = "bpf",
57 .revision = 0,
58 .family = NFPROTO_UNSPEC,
59 .checkentry = bpf_mt_check,
60 .match = bpf_mt,
61 .destroy = bpf_mt_destroy,
62 .matchsize = sizeof(struct xt_bpf_info),
63 .usersize = offsetof(struct xt_bpf_info, filter),
64 .me = THIS_MODULE,
65 };
66
bpf_mt_init(void)67 static int __init bpf_mt_init(void)
68 {
69 return xt_register_match(&bpf_mt_reg);
70 }
71
bpf_mt_exit(void)72 static void __exit bpf_mt_exit(void)
73 {
74 xt_unregister_match(&bpf_mt_reg);
75 }
76
77 module_init(bpf_mt_init);
78 module_exit(bpf_mt_exit);
79