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;
30 if (len > XT_BPF_MAX_NUM_INSTR)
34 program.filter = insns;
36 if (bpf_prog_create(ret, &program)) {
37 pr_info("bpf: check failed: parse error\n");
44 static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
46 struct bpf_prog *prog;
48 prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
56 static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
58 mm_segment_t oldfs = get_fs();
61 if (strnlen(path, XT_BPF_PATH_MAX) == XT_BPF_PATH_MAX)
65 fd = bpf_obj_get_user(path);
70 retval = __bpf_mt_check_fd(fd, ret);
75 static int bpf_mt_check(const struct xt_mtchk_param *par)
77 struct xt_bpf_info *info = par->matchinfo;
79 return __bpf_mt_check_bytecode(info->bpf_program,
80 info->bpf_program_num_elem,
84 static int bpf_mt_check_v1(const struct xt_mtchk_param *par)
86 struct xt_bpf_info_v1 *info = par->matchinfo;
88 if (info->mode == XT_BPF_MODE_BYTECODE)
89 return __bpf_mt_check_bytecode(info->bpf_program,
90 info->bpf_program_num_elem,
92 else if (info->mode == XT_BPF_MODE_FD_ELF)
93 return __bpf_mt_check_fd(info->fd, &info->filter);
94 else if (info->mode == XT_BPF_MODE_PATH_PINNED)
95 return __bpf_mt_check_path(info->path, &info->filter);
100 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
102 const struct xt_bpf_info *info = par->matchinfo;
104 return BPF_PROG_RUN(info->filter, skb);
107 static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
109 const struct xt_bpf_info_v1 *info = par->matchinfo;
111 return !!bpf_prog_run_save_cb(info->filter, (struct sk_buff *) skb);
114 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
116 const struct xt_bpf_info *info = par->matchinfo;
118 bpf_prog_destroy(info->filter);
121 static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par)
123 const struct xt_bpf_info_v1 *info = par->matchinfo;
125 bpf_prog_destroy(info->filter);
128 static struct xt_match bpf_mt_reg[] __read_mostly = {
132 .family = NFPROTO_UNSPEC,
133 .checkentry = bpf_mt_check,
135 .destroy = bpf_mt_destroy,
136 .matchsize = sizeof(struct xt_bpf_info),
137 .usersize = offsetof(struct xt_bpf_info, filter),
143 .family = NFPROTO_UNSPEC,
144 .checkentry = bpf_mt_check_v1,
146 .destroy = bpf_mt_destroy_v1,
147 .matchsize = sizeof(struct xt_bpf_info_v1),
148 .usersize = offsetof(struct xt_bpf_info_v1, filter),
153 static int __init bpf_mt_init(void)
155 return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
158 static void __exit bpf_mt_exit(void)
160 xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
163 module_init(bpf_mt_init);
164 module_exit(bpf_mt_exit);