1 /* Xtables module to match packets using a BPF filter.
2 * Copyright 2013 Google Inc.
3 * Written by Willem de Bruijn <willemb@google.com>
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.
10 #include <linux/module.h>
11 #include <linux/syscalls.h>
12 #include <linux/skbuff.h>
13 #include <linux/filter.h>
14 #include <linux/bpf.h>
16 #include <linux/netfilter/xt_bpf.h>
17 #include <linux/netfilter/x_tables.h>
19 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
20 MODULE_DESCRIPTION("Xtables: BPF filter match");
21 MODULE_LICENSE("GPL");
22 MODULE_ALIAS("ipt_bpf");
23 MODULE_ALIAS("ip6t_bpf");
25 static int __bpf_mt_check_bytecode(struct sock_filter *insns, __u16 len,
26 struct bpf_prog **ret)
28 struct sock_fprog_kern program;
31 program.filter = insns;
33 if (bpf_prog_create(ret, &program)) {
34 pr_info("bpf: check failed: parse error\n");
41 static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
43 struct bpf_prog *prog;
45 prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
53 static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
55 mm_segment_t oldfs = get_fs();
59 fd = bpf_obj_get_user(path);
64 retval = __bpf_mt_check_fd(fd, ret);
69 static int bpf_mt_check(const struct xt_mtchk_param *par)
71 struct xt_bpf_info *info = par->matchinfo;
73 return __bpf_mt_check_bytecode(info->bpf_program,
74 info->bpf_program_num_elem,
78 static int bpf_mt_check_v1(const struct xt_mtchk_param *par)
80 struct xt_bpf_info_v1 *info = par->matchinfo;
82 if (info->mode == XT_BPF_MODE_BYTECODE)
83 return __bpf_mt_check_bytecode(info->bpf_program,
84 info->bpf_program_num_elem,
86 else if (info->mode == XT_BPF_MODE_FD_ELF)
87 return __bpf_mt_check_fd(info->fd, &info->filter);
88 else if (info->mode == XT_BPF_MODE_PATH_PINNED)
89 return __bpf_mt_check_path(info->path, &info->filter);
94 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
96 const struct xt_bpf_info *info = par->matchinfo;
98 return BPF_PROG_RUN(info->filter, skb);
101 static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
103 const struct xt_bpf_info_v1 *info = par->matchinfo;
105 return !!bpf_prog_run_save_cb(info->filter, (struct sk_buff *) skb);
108 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
110 const struct xt_bpf_info *info = par->matchinfo;
112 bpf_prog_destroy(info->filter);
115 static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par)
117 const struct xt_bpf_info_v1 *info = par->matchinfo;
119 bpf_prog_destroy(info->filter);
122 static struct xt_match bpf_mt_reg[] __read_mostly = {
126 .family = NFPROTO_UNSPEC,
127 .checkentry = bpf_mt_check,
129 .destroy = bpf_mt_destroy,
130 .matchsize = sizeof(struct xt_bpf_info),
131 .usersize = offsetof(struct xt_bpf_info, filter),
137 .family = NFPROTO_UNSPEC,
138 .checkentry = bpf_mt_check_v1,
140 .destroy = bpf_mt_destroy_v1,
141 .matchsize = sizeof(struct xt_bpf_info_v1),
142 .usersize = offsetof(struct xt_bpf_info_v1, filter),
147 static int __init bpf_mt_init(void)
149 return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
152 static void __exit bpf_mt_exit(void)
154 xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
157 module_init(bpf_mt_init);
158 module_exit(bpf_mt_exit);