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 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 program; 27 28 program.len = info->bpf_program_num_elem; 29 program.filter = (struct sock_filter __user *) info->bpf_program; 30 if (sk_unattached_filter_create(&info->filter, &program)) { 31 pr_info("bpf: check failed: parse error\n"); 32 return -EINVAL; 33 } 34 35 return 0; 36 } 37 38 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par) 39 { 40 const struct xt_bpf_info *info = par->matchinfo; 41 42 return SK_RUN_FILTER(info->filter, skb); 43 } 44 45 static void bpf_mt_destroy(const struct xt_mtdtor_param *par) 46 { 47 const struct xt_bpf_info *info = par->matchinfo; 48 sk_unattached_filter_destroy(info->filter); 49 } 50 51 static struct xt_match bpf_mt_reg __read_mostly = { 52 .name = "bpf", 53 .revision = 0, 54 .family = NFPROTO_UNSPEC, 55 .checkentry = bpf_mt_check, 56 .match = bpf_mt, 57 .destroy = bpf_mt_destroy, 58 .matchsize = sizeof(struct xt_bpf_info), 59 .me = THIS_MODULE, 60 }; 61 62 static int __init bpf_mt_init(void) 63 { 64 return xt_register_match(&bpf_mt_reg); 65 } 66 67 static void __exit bpf_mt_exit(void) 68 { 69 xt_unregister_match(&bpf_mt_reg); 70 } 71 72 module_init(bpf_mt_init); 73 module_exit(bpf_mt_exit); 74