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_kern program; 27 28 program.len = info->bpf_program_num_elem; 29 program.filter = info->bpf_program; 30 31 if (bpf_prog_create(&info->filter, &program)) { 32 pr_info("bpf: check failed: parse error\n"); 33 return -EINVAL; 34 } 35 36 return 0; 37 } 38 39 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par) 40 { 41 const struct xt_bpf_info *info = par->matchinfo; 42 43 return BPF_PROG_RUN(info->filter, skb); 44 } 45 46 static void bpf_mt_destroy(const struct xt_mtdtor_param *par) 47 { 48 const struct xt_bpf_info *info = par->matchinfo; 49 bpf_prog_destroy(info->filter); 50 } 51 52 static struct xt_match bpf_mt_reg __read_mostly = { 53 .name = "bpf", 54 .revision = 0, 55 .family = NFPROTO_UNSPEC, 56 .checkentry = bpf_mt_check, 57 .match = bpf_mt, 58 .destroy = bpf_mt_destroy, 59 .matchsize = sizeof(struct xt_bpf_info), 60 .me = THIS_MODULE, 61 }; 62 63 static int __init bpf_mt_init(void) 64 { 65 return xt_register_match(&bpf_mt_reg); 66 } 67 68 static void __exit bpf_mt_exit(void) 69 { 70 xt_unregister_match(&bpf_mt_reg); 71 } 72 73 module_init(bpf_mt_init); 74 module_exit(bpf_mt_exit); 75